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| | 1. |
2010 Oct 19 |
Aerobic cometabolic degradation of trichloroethene by methane and ammonia oxidizing microorganisms naturally associated with Carex comosa roots.
Powell CL, Nogaro G, Agrawal A
Biodegradation. 2010 Oct 19; [Epub ahead of print]
Abstract
The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade 150 μg l(-1) TCE effectively at 1.9 mg l(-1) of aqueous CH(4). In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 μg l(-1) TCE at 20 mg l(-1) of NH(4) (+)-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated aquatic environments.
[Pubmed: 20957410]
| | 2. |
2011 Feb 16 |
Nitrous oxide fluxes from the littoral zone of a lake on the Qinghai-Tibetan Plateau.
Chen H, Wang M, Wu N, Wang Y, Zhu D, Gao Y, Peng C
Environ Monit Assess. 2011 Feb 16; [Epub ahead of print]
Abstract
Nitrous oxide (N(2)O) fluxes were measured in six littoral mirco-zones of Lake Huahu on Qinghai-Tibetan Plateau in the peak growing season of years of 2006 and 2007. The weighted mean N(2)O flux rate was 0.08 mg N m( - 2) h( - 1) (ranged from -0.07 to 0.35 mg N m( - 2) h( - 1)). The result was relatively high in the scope of N(2)O fluxes from boreal and temperate lakes. Emergent plant zones (Hippuris vulgaris and Glyceria maxima stands) recorded the highest N(2)O flux rate (0.11 ± 0.24 and 0.08 ± 0.17 mg N m( - 2) h( - 1), respectively). Non-vegetated lakeshore recorded the lowest N(2)O flux (0.03 ± 0.11 mg N m( - 2) h( - 1)), lower than that from the floating mat zone of Carex muliensis (0.05 ± 0.18 mg N m( - 2) h( - 1)), the floating-leaved plant zone of Polygonum amphibium (0.07 ± 0.11 mg N m( - 2) h( - 1)), and the wet meadow (0.07 ± 0.15 mg N m( - 2) h( - 1)). Standing water depths were important factors to explain such spatial variations in N(2)O fluxes. Significant temporal variations in N(2)O fluxes were also found. Such temporal variation in N(2)O flux in the littoral zone may be dependent on the interaction of water regime and thermal conditions, instead of the latter solely. These results showed the importance of the littoral zone of lake, especially the emergent plant zone, as a hotspot of N(2)O fluxes in such grazing meadows.
[Pubmed: 21327481]
| | 3. |
2011 May 13 |
Herbiconiux flava sp. nov., and emended description of the genus Herbiconiux.
Hamada M, Komukai C, Tamura T, Evtushenko LI, Vinokurova NG, Suzuki KI
Int J Syst Evol Microbiol. 2011 May 13; [Epub ahead of print]
Abstract
The rod-shaped, non-motile and non-endospore-forming strain NBRC 16403(T) (=VKM Ac-2058(T)) was isolated from the phyllosphere of a sedge (Carex sp.). 16S rRNA gene sequencing studies indicated that strain NBRC 16403(T) was closely related to the type strains of Herbiconiux solani (98.6 %), Herbiconiux ginsengi (97.8 %) and Herbiconiux moechotypicola (97.8 %). The peptidoglycan (B2γ type) contained D- and L-2,4-diaminobutyric acids, D-alanine, glycine and threo-3-hydroxyglutamic acid which almost fully substituted glutamic acid. The predominant menaquinones were MK-10 and MK-11. The polar lipid pattern comprised diphosphatidylglycerol, phosphatidylglycerol and three glycolipids, along with, along with minor amounts of other polar lipids. The major fatty acids were anteiso-C(15:0), iso-C(16:0) and anteiso-C(17:0); no cyclohexyl-C(17:0) was detected. The DNA G+C content was 71.0 mol%. The results of phylogenetic analysis and DNA-DNA hybridization, along with differences of strain NBRC 16403(T) from the recognized Herbiconiux species in phenotypic characteristics, indicate that a novel species of the genus Herbiconiux, for which the name Herbiconiux flava sp. nov. is proposed. The type strain is NBRC 16403(T) (=VKM Ac-2058(T)).
[Pubmed: 21571941]
| | 4. |
2011 Apr 15 |
Environmental metabolomics links genotype to phenotype and predicts genotype abundance in wild plant populations.
Field KJ, Lake JA
Physiol Plant. 2011 Apr 15; [Epub ahead of print]
Abstract
'The Holy Grail' of plant ecology is to uncover rules that associate species and traits with environmental constraints, community composition and subsequent ecosystem functioning. These aims have been crystallized in recent years within the context of global climate change and environmental pollution, increasing the urgency of the need to predict how vegetation will respond across spatial scales. We investigated whether genetic diversity is associated with the way in which phenotypic plasticity within plant populations is realized and whether this is related to genotype abundance. We used environmental metabolomics to demonstrate biochemical variation between co-occurring genotypes of Carex caryophyllea L. A novel combined metabolomic/functional trait analysis was used to test the functionality of this variation in governing plasticity to variation in edaphic conditions, with particular reference to metabolic pathways that play important roles in growth-related traits. We show that genetic diversity within a wild C. caryophyllea population relates to differences in metabolic composition and functional traits in response to soil nutrient variation, influencing genotype abundance within a community. Our findings highlight the vital role genetic diversity plays within a population in facilitating plant phenotypic plasticity and the potential usefulness of environmental metabolomics to future ecological studies.
[Pubmed: 21496032]
| | 5. |
2011 Feb 22 |
Surface energy fluxes and control of evapotranspiration from a Carex lasiocarpa mire in the Sanjiang Plain, Northeast China.
Guo Y, Sun L
Int J Biometeorol. 2011 Feb 22; [Epub ahead of print]
Abstract
Data from four components of the radiation balance were used to investigate the surface energy budgets for a Carex lasiocarpa mire in the Sanjiang Plain, Northeast China, and the controlling factors of the evapotranspiration (ET) were discussed in detail. During the growing season 2006, the shortwave radiation (SW↓) reaching the mire surface added up to 2,854.3 MJ m(-2) and the net radiation (Rn) was 1,637.4 MJ m(-2) in total, with an average of 9.86 MJ m(-2) day(-1). G was the smallest flux at the water-atmosphere interface, with an average of about 0.91 MJ m(-2) day(-1), but showed high relative variability, even changing its sign. The latent and sensible heat fluxes (LE and H) amounted to 787.48 and 476.26 MJ m(-2), respectively, and the total sum of LE and H accounted for 77.18% of Rn. By conversion from LE, the average value of ET from the mire was 1.84 mm day(-1), amounting to 298.8 mm. The total ET was almost 60% of the total rainfall in the same period, proving that ET is the primary water consumer in the mire. The growth of C. lasiocarpa was related closely with surface resistance (r (s)), and analysis of partial correlation indicated that r (s) correlated negatively with leaf area index (LAI) when the interference of the available energy, Rn-G, was removed. There was a strong linkage between r (s) and the evaporative fraction [LE/(LE + H)] as well as Bowen ratio (β). r (s) was the key factor in controlling the variation of ET and regulating energy partitioning between LE and H. During the whole growing season, r (s) and R (n)-G were the two main factors coupled in ET processes. In spring, r (s) dominated ET processes, and the increase in LAI led to a decrease in r (s), which in turn accelerated ET as vegetation developed until late August. After August, the available energy controlled the process of ET completely until ET reached an equilibrium in mid-October.
[Pubmed: 21340659]
| | 6. |
2011 Jul 25 |
Resveratrol Oligomers Isolated from Carex Species Inhibit Growth of Human Colon Tumorigenic Cells Mediated by Cell Cycle Arrest.
González-Sarrías A, Gromek S, Niesen D, Seeram NP, Henry GE
J Agric Food Chem. 2011 Aug 24;59(16):8632-8638. Epub 2011 Jul 25.
Abstract
Research has shown that members of the Carex genus produce biologically active stilbenoids including resveratrol oligomers. This is of great interest to the nutraceutical industry given that resveratrol, a constituent of grape and red wine, has attracted immense research attention due to its potential human health benefits. In the current study, five resveratrol oligomers (isolated from Carex folliculata and Carex gynandra ), along with resveratrol, were evaluated for antiproliferative effects against human colon cancer (HCT-116, HT-29, Caco-2) and normal human colon (CCD-18Co) cells. The resveratrol oligomers included one dimer, two trimers, and two tetramers: pallidol (1); α-viniferin (2) and trans-miyabenol C (3); and kobophenols A (4) and B (5), respectively. Although not cytotoxic, the resveratrol oligomers (1-5), as well as resveratrol, inhibited growth of the human colon cancer cells. Among the six stilbenoids, α-viniferin (2) was most active against the colon cancer cells with IC(50) values of 6-32 μM (>2-fold compared to normal colon cells). Moreover, α-viniferin (at 20 μM) did not induce apoptosis but arrested cell cycle (in the S-phase) for the colon cancer but not the normal colon cells. This study adds to the growing body of knowledge supporting the anticancer effects of resveratrol and its oligomers. Furthermore, Carex species should be investigated for their nutraceutical potential given that they produce biologically active stilbenoids such as α-viniferin.
[Pubmed: 21761862]
| | 7. |
2011 Jul |
Formation of tussocks by sedges: effects of hydroperiod and nutrients.
Lawrence BA, Zedler JB
Ecol Appl. 2011 Jul;21(5):1745-59.
Abstract
Tussock formation is a global phenomenon that enhances microtopography and increases biodiversity by adding structure to ecological communities, but little is known about tussock development in relation to environmental factors. To further efforts to restore wetland microtopography and associated functions, we investigated Carex stricta tussock size in relation to elevation (a proxy for water depth) at a range of sites in southern Wisconsin, USA, and tested the effect of five hydroperiods and N+P addition (15 g N/m2 + 0.37 g P/m2) on tussock formation during a three-year mesocosm experiment. Wet meadows dominated by C. stricta averaged 4.9 tussocks/m2, with a mean volume of 1160 cm3 and height of 15 cm. Within sites, taller tussocks occurred at lower elevations, suggesting a structural adaptation to anoxic conditions. In our mesocosm experiment, C. stricta accelerated tussock formation when inundated, and it increased overall productivity with N + P addition. Within two growing seasons, continuous inundation (+18 cm) in the mesocosms led to tussocks that were nearly as tall as in our field survey (mean height in mesocosms, 10 +/- 1.3 cm; maximum, 17 cm). Plants grown with constant low water (-18 cm) only formed short mounds (mean height = 2 +/- 0.4 cm). After three growing seasons, the volume of the largest tussocks (3274 +/- 376 cm3, grown with +18 cm water depth and N + P addition) was 12 times that of the smallest (275 +/- 38 cm3, grown with -18 cm water depth and no N + P). Though tussock composition varied among hydroperiods, tussocks were predominantly organic (74-94% of dry mass) and composed of leaf bases (46-59%), fine roots (10-31%), and duff (5-13%). Only the plants subjected to high water levels produced the vertically oriented rhizomes and ascending shoot bases that were prevalent in field-collected tussocks. Under continuous or periodic inundation, tussocks achieved similar heights and accumulated similar levels of organic matter (range: 163-394 g C/m2), and we conclude that these hydroperiods can accelerate tussock formation. Thus, C. stricta has high utility for restoring wetland microtopography and associated functions, including carbon accumulation.
[Pubmed: 21830715]
| | 8. |
|
CAREX Nicaragua and Panama: Worker exposures to carcinogenic substances and pesticides.
Blanco-Romero LE, Vega LE, Lozano-Chavarría LM, Partanen TJ
Int J Occup Environ Health.;17(3):251-7.
Abstract
This study provides data on numbers of workers exposed at work to selected carcinogens and pesticides in Nicaragua (35 substances) and Panama (31), based on a modification of the CAREX data system. Population censuses provided industry- and sex-specific workforce numbers. The activity- and sex-specific proportions of exposed workers were estimated by experts from governmental agencies, workers' organizations, and employers' representatives. Finally, the numbers of those occupied in each activity/sex category were multiplied by the proportions of those exposed in the same categories, yielding numbers of those exposed in these categories for each agent. The study revealed high proportions (> 9%) of occupationally exposed workers in both countries for solar radiation and diesel engine emissions; environmental tobacco smoke in Panama; and some pesticides in Nicaragua. A high proportion of exposed was found for men for lead (12%), silica dust (10%), and hexavalent chromium (10%) in Panama.
[Pubmed: 21905394]
| | 9. |
2011 Jul |
Effects of light regime, temperature, and plant age on uptake of arsenic by Spartina pectinata and Carex stricta.
Rofkar JR, Dwyer DF
Int J Phytoremediation. 2011 Jul;13(6):528-37.
Abstract
We report here on efforts to show that a combination of native wetland plant species might perform better than a monoculture in wetlands designed for arsenic remediation by supplementing weaknesses. Carex stricta and Spartina pectinata were used in hydroponic experiments. (i) Arsenic uptake was first assessed at two ages via exposure to control or arsenic-laden solutions (0 or 1.5 mg As L(-1) as Na2HAsO4) for two weeks. Age had no significant effect on arsenic concentrations in roots, but translocation factors were greater in older plants of C. stricta and S. pectinata (0.45 and 0.07, respectively) than in younger plants (0.10 and 0.01, respectively). (ii) Seasonal effects were assessed by determining uptake kinetics for both species in conditions representative of spring temperatures (15/5 degrees C) and light regimes (1050 micromol m(-2) s(-1), 13 h day(-1)) and summer temperatures (28/17 degrees C) and light regimes (1300 micromol m(-2) s(-1), 15 h day(-1)). Both species had comparable rates of arsenic uptake into roots in summer conditions (44.0 and 46.5 mg As kg(-1) dry wt. h(-1) in C. stricta and S. pectinata, respectively), but C. stricta had a higher maximum net influx rate in spring conditions (24.5 versus 10.4 mg As kg(-1) dry wt. h(-1)).
[Pubmed: 21972500]
| | 10. |
2011 Jun |
[Characteristics of CO2 emission from Carex-dominated wetland in Poyang Lake in non-flooded period].
Hu QW, Xing RX, Zhu LL, Wu Q, Yao B, Liu Y, Hu BH
Ying Yong Sheng Tai Xue Bao. 2011 Jun;22(6):1431-6.
Abstract
By using static chamber/gas chromatography, the CO2 fluxes in a Carex cinerascen-dominated wetland in the Poyang Lake Nanji Wetland National Nature Reserve were measured in nonflooded period (from September 2009 to April 2010). Two treatments were installed, i. e. , soil-plant system (TC) and aboveground plant removal (TJ), representing ecosystem respiration and soil respiration, respectively. There was an obvious seasonal variation in the ecosystem respiration and soil respiration. The respiration rate in treatment TC ranged from 89.57 to 1243.99 mg CO2 x m(-2) x h(-1), and that in TJ was from 75.30 to 960.94 mg CO2 x m(-2) x h(-1). Soil respiration accounted for 39% -84% of ecosystem respiration, with an average of 64%. Soil temperature was the main factor controlling the ecosystem respiration and soil respiration, explaining more than 80% of the respiration variance. The temperature coefficient (Q10), an index of temperature sensitivity for respiration, was 3.31 for ecosystem respiration and 2.75 for soil respiration. The Q10 value was higher in winter than in autumn and spring. No significant correlation was observed between soil moisture and CO2 fluxes. In non-flooded period, the C. cinerascens-dominated wetland acted as a carbon sink of atmospheric CO2, with a carbon uptake of 1717.72 g C x m(-2).
[Pubmed: 21941741]
| | 11. |
2011 Oct 19 |
Ecophysiological mechanisms characterising fen and bog species: focus on variations in nitrogen uptake traits under different soil-water pH.
Nakamura T, Nakamura M
Oecologia. 2011 Oct 19; [Epub ahead of print]
Abstract
Although the productivity and nitrogen (N)-use traits of mire plants differ dramatically between fens and bogs, soil N richness does not necessarily differ, whereas the soil-water pH is distinctly lower in bogs than in fens. The ecophysiological mechanisms underlying these relations are unclear. To assess the relative availability of N forms in relation to soil-water pH, we focused on the net N uptake rate per unit root weight (NNUR), glutamine synthetase activity and nitrate reductase activity, and performed reciprocal transplant experiments with the seedlings of fen (Carex lyngbyei) and bog (C. middendorffii) sedge species in intact habitat sites. The soil-water pH was clearly lower at the bog site, but the NH(4) (+), NO(3) (-) or dissolved organic-N concentrations did not differ between the fen and bog sites. The activity of both enzymes for inorganic-N assimilation did not differ among the sites and species. However, the fen species grown at bog sites showed a drastic decrease in the NNUR, suggesting a suppression of organic-N uptake. The bog species showed no NNUR difference between the sites. These results indicate that inorganic-N availability does not differ between the two habitats, but organic-N availability is lowered in a low-pH bog, particularly in the case of fen species. Therefore, the relative availability of N forms shows species-specific variations that depend on the differences in the soil-water pH of root zone, even at similar N richness, which would play a key role in plant distribution strategies in relation to the fen-bog gradient.
[Pubmed: 22009342]
| | 12. |
2011 Nov 10 |
AFLP markers reveal high clonal diversity and extreme longevity in four key arctic-alpine species.
De Witte LC, Armbruster GF, Gielly L, Taberlet P, Stöcklin J
Mol Ecol. 2011 Nov 10; [Epub ahead of print]
Abstract
We investigated clonal diversity, genet size structure and genet longevity in populations of four arctic-alpine plants (Carex curvula, Dryas octopetala, Salix herbacea and Vaccinium uliginosum) to evaluate their persistence under past climatic oscillations and their potential resistance to future climate change. The size and number of genets were determined by an analysis of amplified fragment length polymorphisms and a standardized sampling design in several European arctic-alpine populations, where these species are dominant in the vegetation. Genet age was estimated by dividing the size by the annual horizontal size increment from in situ growth measurements. Clonal diversity was generally high but differed among species, and the frequency distribution of genet size was strongly left-skewed. The largest C. curvula genet had an estimated minimum age of c. 4100 years and a maximum age of c. 5000 years, although 84.8% of the genets in this species were <200 years old. The oldest genets of D. octopetala, S. herbacea and V. uliginosum were found to be at least 500, 450 and 1400 years old, respectively. These results indicate that individuals in the studied populations have survived pronounced climatic oscillations, including the Little Ice Age and the postindustrial warming. The presence of genets in all size classes and the dominance of presumably young individuals suggest repeated recruitment over time, a precondition for adaptation to changing environmental conditions. Together, persistence and continuous genet turnover may ensure maximum ecosystem resilience. Thus, our results indicate that long-lived clonal plants in arctic-alpine ecosystems can persist, despite considerable climatic change.
[Pubmed: 22070158]
| | 13. |
2011 Oct 24 |
Taxonomic delimitation and drivers of speciation in the Ibero-North African Carex sect. Phacocystis river-shore group (Cyperaceae).
Jiménez-Mejías P, Escudero M, Guerra-Cárdenas S, Lye KA, Luceño M
Am. J. Bot. 2011 Nov;98(11):1855-67. Epub 2011 Oct 24.
Abstract
• Premise of the study: The Ibero-North African Carex sect. Phacocystis river-shore group is a set of perennial helophytic species with poorly defined taxonomic boundaries. In the present study, we delimited the different taxonomic units, addressed the phylogeographic history, and evaluated the drivers of differentiation that have promoted diversification of these plants. • Methods: We analyzed molecular data using statistical parsimony for plastid sequences (26 samples from 26 populations) and principal coordinate analysis, neighbor joining, and Bayesian analysis of population structure for AFLPs (186 samples from 26 populations). Chromosome numbers from 14 samples (9 populations) are newly reported. • Key results: Three species can be distinguished (C. acuta, C. elata, and C. reuteriana). Unexpectedly for rhizome-growing helophytes, the vegetative reproduction detected was incidental. The widespread C. elata was found to be a genetically poorly differentiated taxon, whereas the local C. reuteriana displayed geographical structuring. Geographical factors seem to be the main driver of differentiation for both taxa. • Conclusions: Despite apparent morphological and ecological similarities, C. elata and C. reuteriana have disparate genetic structures and evolutionary histories, which may have originated from small ecological differences. Carex elata is broadly distributed throughout Europe, and its northern populations were recently founded, probably after the last glacial maximum. In contrast, C. reuteriana is an Ibero-North African endemic, with long-standing populations affected by isolation and limited gene flow. It is likely that high-density blocking effects and different gene-flow barriers act together to delimit its distribution and promote its relatively high population differentiation.
[Pubmed: 22025295]
| | 14. |
2011 Nov 28 |
Microsatellite primers in Carex moorcroftii (Cyperaceae), a dominant species of the steppe on the Qinghai-Tibetan Plateau.
Liu W, Zhou Y, Liao H, Zhao Y, Song Z
Am. J. Bot. 2011 Dec;98(12):e382-4. Epub 2011 Nov 28.
Abstract
• Premise of the study: Microsatellite markers were developed in Carex moorcroftii, a rhizomatous clonal sedge that dominates the steppes and meadows of the Qinghai-Tibetan Plateau. • Methods and Results: Using the combined biotin capture method, 30 microsatellite primer sets were isolated and characterized. Twenty-two of these markers showed polymorphism, and the number of alleles per locus ranged from two to 11 across 96 individuals from four populations. • Conclusions: These markers provide a useful tool to investigate the clonal structure and mating system of C. moorcroftii.
[Pubmed: 22123716]
| | 15. |
2011 Dec 10 |
Community Structure, Abundance, and Activity of Methanotrophs in the Zoige Wetland of the Tibetan Plateau.
Yun J, Zhuang G, Ma A, Guo H, Wang Y, Zhang H
Microb Ecol. 2011 Dec 10; [Epub ahead of print]
Abstract
The Zoige wetland of the Tibetan Plateau is a high-altitude tundra wetland and one of the biggest methane emission centers in China. In this study, methanotrophs with respect to community structure, abundance, and activity were investigated in peat soils collected in the vicinity of different marshland plants that dominate different regions of the wetland, including Polygonum amphibium, Carex muliensis, and Eleocharis valleculosa (EV). 16S rRNA gene and particulate methane monooxygenase gene (pmoA) clone library sequence data indicated the presence of methanotrophs with two genera, Methylobacter and Methylocystis. Methylococcus, like pmoA gene sequences, were also retrieved and showed low similarity to those from Methylococcus spp. and thus indicates the existence of novel methanotrophs in the Zoige wetland. Quantitative polymerase chain reaction (qPCR) assays were used to measure the abundance of methantrophs and detected 10(7) to 10(8) of total pmoA gene copies per gram dry weight of soil in the three marshes. Group-specific qPCR and reverse transcriptase qPCR results found that the Methylobacter genus dominates the wetland, and Methylocystis methanotrophs were less abundant, although this group of methanotrophs was estimated to be more active according to mRNA/DNA ratio. Furthermore, EV marsh demonstrated the highest methanotrophs abundance and activity among the three marshes investigated. Our study suggests that both type I and type II methanotrophs contribute to the methane oxidation in the Zoige wetland.
[Pubmed: 22159497]
| | 16. |
2012 Jan 5 |
The impact of dissolved organic carbon on the spatial variability of methanogenic archaea communities in natural wetland ecosystems across China.
Liu D, Ding W, Jia Z, Cai Z
Appl Microbiol Biotechnol. 2012 Jan 5; [Epub ahead of print]
Abstract
Significant spatial variation in CH(4) emissions is a well-established feature of natural wetland ecosystems. To understand the key factors affecting CH(4) production, the variation in community structure of methanogenic archaea, in relation to substrate and external environmental influences, was investigated in selected wetlands across China, using denaturing gradient gel electrophoresis. Case study areas were the subtropical Poyang wetland, the warm-temperate Hongze wetland, the cold-temperate Sanjiang marshes, and the alpine Ruoergai peatland on the Qinghai-Tibetan Plateau. The topsoil layer in the Hongze wetland exhibited the highest population of methanogens; the lowest was found in the Poyang wetland. Maximum CH(4) production occurred in the topsoil layer of the Sanjiang Carex lasiocarpa marsh, the minimum was observed in the Ruoergai peatland. CH(4) production potential was significantly correlated with the dissolved organic carbon (DOC) concentration but not with the abundance or diversity indices of methanogenic archaea. Phylogenetic analysis and DOC concentration indicated a shift in the dominant methanogen from the hydrogenotrophic Methanobacteriales in DOC-rich wetlands to Methanosarcinaceae with a low affinity in wetlands with relatively high DOC and then to the acetotrophic methanogen Methanosaetaceae with a high affinity in wetlands with low DOC, or with high DOC but rich sulfate-reducing bacteria. Therefore, it is proposed that the dominant methanogen type in wetlands is primarily influenced by available DOC concentration. In turn, the variation in CH(4) production potential in the wetlands of eastern China is attributable to differences in the DOC content and the dominant type of methanogen present.
[Pubmed: 22218772]
| | 17. |
2012 Mar |
Out in the cold - how big and how old? Genetic fingerprinting reveals long-lived individuals withstand climatic oscillations in the arctic-alpine.
Miller A
Mol. Ecol. 2012 Mar;21(5):1036-7.
Abstract
In long-lived, clonally reproducing species, assessing organism size is a nontrivial endeavour because each genetically distinct entity (genet) may comprise multiple modular units (ramets). Attributes of clonally reproducing populations, such as genet size, longevity and clonal diversity (the number of genets in a population), have significant implications for the persistence of populations over time. In the context of climate change, population persistence contributes to community stability and ecosystem resilience. Do clonal individuals persist through periods of climatic oscillations? Are clonal populations composed of a few large and persistent clones, or do they include clones of different sizes and ages? In this issue, de Witte et al. (2012) present an exciting analysis of clonal diversity and genet longevity in populations of four arctic-alpine plant species with contrasting life histories: Carex curvula, Dryas octopetala, Salix herbacea and Vaccinium uliginosum. Using amplified fragment length polymorphism (AFLP) data, the authors demonstrate that genet size ranged from a few centimetres to 18 metres and age estimates for the largest genets ranged from 500 to 4900 years. These data reveal that clonally reproducing populations include individuals that have outlived significant changes in climate. Despite the longevity of some individuals, clonal diversity within populations was high, with most individuals existing as small, relatively young genets. Long-lived individuals, together with high numbers of younger plants, ensure repeated recruitment and population persistence over time. This study represents a novel and timely contribution to a growing body of work aimed at understanding population persistence in changing climates.
[Pubmed: 22360454]
| | 18. |
2012 Feb 19 |
Diversification rates and chromosome evolution in the most diverse angiosperm genus of the temperate zone (Carex, Cyperaceae).
Escudero M, Hipp AL, Waterway MJ, Valente LM
Mol Phylogenet Evol. 2012 Feb 19; [Epub ahead of print]
Abstract
The sedge family (Cyperaceae: Poales; ca. 5600 spp.) is a hyperdiverse cosmopolitan group with centres of species diversity in Africa, Australia, eastern Asia, North America, and the Neotropics. Carex, with ca. 40% of the species in the family, is one of the most species-rich angiosperm genera and the most diverse in temperate regions of the Northern Hemisphere, making it atypical among plants in that it inverts the latitudinal gradient of species richness. Moreover, Carex exhibits high rates of chromosome rearrangement via fission, fusion, and translocation, which distinguishes it from the rest of the Cyperaceae. Here, we use a phylogenetic framework to examine how the onset of contemporary temperate climates and the processes of chromosome evolution have influenced the diversification dynamics of Carex. We provide estimates of diversification rates and map chromosome transitions across the evolutionary history of the main four clades of Carex. We demonstrate that Carex underwent a shift in diversification rates sometime between the Late Eocene and the Oligocene, during a global cooling period, which fits with a transition in diploid chromosome number. We suggest that adaptive radiation to novel temperate climates, aided by a shift in the mode of chromosome evolution, may explain the large-scale radiation of Carex and its latitudinal pattern of species richness.
[Pubmed: 22366369]
| | 19. |
2012 Mar |
[Plant communities in the terrestrial-aquatic transition zone in the paramo of Chingaza, Colombia].
Schmidt-Mumm U, Vargas Ríos O
Rev. Biol. Trop. 2012 Mar;60(1):35-64.
Abstract
Plant communities in the terrestrial-aquatic transition zone in the paramo of Chingaza, Colombia. High Andean paramo ecosystems are an important water resource for many towns, and major cities in this region. The aquatic and wetland vegetation of different paramo lakes, pond, swamps and bogs was studied according to the classical phytosociological approach, which is based on homogenous stands, but excludes any border phenomena or transitional zone. The present research aimed at determining the aquatic and wetland vegetation along different moisture gradients. A total of 89 species in 30 transects were reported, of which Crassula venezuelensis, Carex honplandii, Callitriche nubigena, Eleocharis macrostachya, Ranunculus flagelliformis, R. nubigenus, Eleocharis stenocarpa, Galium ascendens y Alopecurus aequalis were present in more than one third of the transects. Numerical classification and indicator species analysis resulted in the definition of the next 18 communities: 1) Calamagrostis effusa, 2) Sphagnum cuspidatum, 3) Cyperus rufus, 4) Eleocharis stenocarpa, 5) Carex acutata, 6) Poa annua,7) Valeriana sp., 8) Ranunculus flagelliformis, 9) Carex bonplandii, 10) Festuca andicola. 11) Muhlenbergia fustigiata, 12) Elatine paramoana, 13) Isoëtes palmeri, 14) Crassula venezuelensis, 15) Lilaeopsis macloviana, 16) Callitriche nubigena, 17) Potamogeton paramoanus and 18) Potamogeton illinoensis. The ordination of communities reveals the presence of three different aquatic-terrestrial gradients which are related to the life form structure of species that characterized the various communities. We concluded that patchiness and heterogeneity of the vegetation is mainly the result of alterations caused by human activities (burning, cattle raise and material extraction for road and dam construction).
[Pubmed: 22458208]
| | 20. |
2012 Apr 10 |
Selection and inertia in the evolution of holocentric chromosomes in sedges (Carex, Cyperaceae).
Escudero M, Hipp AL, Hansen TF, Voje KL, Luceño M
New Phytol. 2012 Apr 10; [Epub ahead of print]
Abstract
• Changes in chromosome number as a result of fission and fusion in holocentrics have direct and immediate effects on the recombination rate. We investigate the support for the classic hypothesis that environmental stability selects for increased recombination rates. • We employed a phylogenetic and cytogenetic data set from one of the most diverse angiosperm genera in the world, which has the largest nonpolyploid chromosome radiation (Carex, Cyperaceae; 2n = 12-124; 2100 spp.). We evaluated alternative Ornstein-Uhlenbeck models of chromosome number adaptation to the environment in an information-theoretic framework. • We found moderate support for a positive influence of lateral inflorescence unit size on chromosome number, which may be selected in a stable environment in which resources for reproductive investment are larger. We found weak support for a positive influence on chromosome number of water-saturated soils and among-month temperature constancy, which would be expected to be negatively select for pioneering species. Chromosome number showed a strong phylogenetic signal. • We argue that our finding of small but significant effects of life history and ecology is compatible with our original hypothesis regarding selection of optima in recombination rates: low recombination rate is optimal when inmediate fitness is required. By contrast, high recombination rate is optimal when stable environments allow for evolutionary innovation.
[Pubmed: 22489934]
| | 21. |
2012 Apr 17 |
Nitrogen critical loads for alpine vegetation and soils in Rocky Mountain National Park.
Bowman WD, Murgel J, Blett T, Porter E
J Environ Manage. 2012 Apr 17;103C:165-171. Epub 2012 Apr 17.
Abstract
We evaluated the ecological thresholds associated with vegetation and soil responses to nitrogen (N) deposition, by adding NH(4)NO(3) in solution at rates of 5, 10 and 30 kg N ha(-1) yr(-1) to plots in a species rich dry meadow alpine community in Rocky Mountain National Park receiving ambient N deposition of 4 kg N ha(-1) yr(-1). To determine the levels of N input that elicited changes, we measured plant species composition annually, and performed one-time measurements of aboveground biomass and N concentrations, soil solution and resin bag inorganic N, soil pH, and soil extractable cations after 3 years of N additions. Our goal was to use these dose-response relationships to provide N critical loads for vegetation and soils for the alpine in Rocky Mountain National Park. Species richness and diversity did not change in response to the treatments, but one indicator species, Carex rupestris increased in cover from 34 to 125% in response to the treatments. Using the rate of change in cover for C. rupestris in the treatment and the ambient plots, and assuming the change in cover was due solely to N deposition, we estimated a N critical load for vegetation at 3 kg N ha(-1) yr(-1). Inorganic N concentrations in soil solution increased above ambient levels at input rates between 9 kg N ha(-1) yr(-1) (resin bags) and 14 kg N ha(-1) yr(-1) (lysimeters), indicating biotic and abiotic sinks for N deposition are exhausted at these levels. No changes in soil pH or extractable cations occurred in the treatment plots, indicating acidification had not occurred after 3 years. We conclude that N critical loads under 10 kg ha(-1) yr(-1) are needed to prevent future acidification of soils and surface waters, and recommend N critical loads for vegetation at 3 kg N ha(-1) yr(-1) as important for protecting natural plant communities and ecosystem services in Rocky Mountain National Park.
[Pubmed: 22516810]
| | 22. |
2012 May 8 |
Impacts of oil sands process water on fen plants: Implications for plant selection in required reclamation projects.
Pouliot R, Rochefort L, Graf MD
Environ Pollut. 2012 May 8;167C:132-137. Epub 2012 May 8.
Abstract
Fen plant growth in peat contaminated with groundwater discharges of oil sands process water (OSPW) was assessed in a greenhouse over two growing seasons. Three treatments (non-diluted OSPW, diluted OSPW and rainwater) were tested on five vascular plants and four mosses. All vascular plants tested can grow in salinity and naphthenic acids levels currently produced by oil sands activity in northwestern Canada. No stress sign was observed after both seasons. Because of plant characteristics, Carex species (C. atherodes and C. utriculata) and Triglochin maritima would be more useful for rapidly restoring vegetation and creating a new peat-accumulating system. Groundwater discharge of OSPW proved detrimental to mosses under dry conditions and ensuring adequate water levels would be crucial in fen creation following oil sands exploitation. Campylium stellatum would be the best choice to grow in contaminated areas and Bryum pseudotriquetrum might be interesting as it has spontaneously regenerated in all treatments.
[Pubmed: 22575093]
| | 23. |
2012 Apr 18 |
Recurrent Outbreaks of Myelodysplasia in Newborn Calves.
Polledo L, García Marín JF, Martínez-Fernández B, González J, Alonso J, Salceda W, García-Iglesias MJ
J Comp Pathol. 2012 Apr 18; [Epub ahead of print]
Abstract
The present study records recurrent outbreaks of myelodysplasia of unknown origin occurring in a specific geographical location in the north of Spain, and involving up to 30% of the calves born in affected herds. The affected calves were of different breeds and displayed non-progressive signs of spinal cord dysfunction. The disease has occurred annually in February-March over a period of at least 15 years. Only calves born to cattle grazed on mountainside pastures and under high grazing pressure were affected. Seven calves were subjected to necropsy examination. Myelodysplasia was not associated with vertebral defects or arthrogryposis and involved the entire length of the spinal cord. Microscopically, there was abnormal distribution of the grey matter, aberrations of the central canal and failure of formation of the ventral median fissure. Infectious, nutritional and physical disorders were ruled out as possible aetiologies. A critical period of embryonic susceptibility to the causal agent was identified. This was during the time of secondary neurulation when cows in the early stages of gestation were grazed on mountainside pastures. Consequently, the presence of neuroteratogenic plants in these pastures is proposed as a likely cause. Two plants, Carex brevicollis and Erythronium dens-canis, which contain alkaloids, were identified on the mountainsides where affected cattle were grazed and not in other pastures, and are proposed as the possible aetiology of the disease.
[Pubmed: 22520815]
| | 24. |
2011 Dec 06 |
Distribution of 152Eu and 154Eu in the 'alluvial soil-rhizosphere-plant roots' system.
Kropatcheva M, Chuguevsky A, Melgunov M
J Environ Radioact. 2012 Apr;106:58-64. Epub 2011 Dec 06.
Abstract
Accumulation of (152)Eu and (15)(4)Eu isotopes in bulk soil and rhizosphere soil in the near-field zone of influence of the Krasnoyarsk Mining and Chemical Combine was studied. An uneven distribution of specific activity of Eu isotopes was observed, with the gross specific activities of the isotopes in the bulk soil exceeding those of the rhizosphere. In the most contaminated locations the fine and the coarse granulometric fractions are enriched with the isotopes. A laboratory experiment indicated potential removal of soluble Eu isotopes by river flood waters may amount to 3% of the total Eu in both bulk and rhizosphere soils. The root system of plants growing in the contaminated territory accumulates (152)Eu and (154)Eu, although the isotopes were not discovered in aboveground parts of plants. Root-hairs were found to be the most contaminated.
[Pubmed: 22305001]
| | 25. |
2012 May 4 |
Impact of Grazing on Soil Carbon and Microbial Biomass in Typical Steppe and Desert Steppe of Inner Mongolia
Liu, Zhang, Chang, Kan, Lin
PLoS One 2012 May 4;7(5). published online before print
Abstract
The potential of grazing lands to sequester carbon must be understood to develop effective soil conservation measures and sustain livestock production. Our objective was to evaluate the effects of grazing on soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC) in Typical steppe and Desert steppe ecosystems, which are both important grassland resources for animal grazing and ecological conservation in China, and to derive region-specific soil C changes associated with different stocking rates (ungrazed, UG; lightly grazed, LG; moderately grazed, MG; heavily grazed, HG). This study substantiated that significant higher SOC, TN and MBC appeared with the treatment of LG in typical steppe. From 2004 to 2010, grazing treatments increased soil carbon storage in desert steppe, which was partly due to the grazing history. The higher MBC concentration and MBC/SOC suggest a great potential for carbon sequestration in the desert steppe ecosystem. The greater MBC in desert steppe than typical steppe was mainly the result of higher precipitation and temperature, instead of soil substrate. The change of MBC and the strong positive relationships between MBC and SOC indicated that MBC in the soil was a sensitive index to indicate the dynamics of soil organic carbon in both steppes in Inner Mongolia of China.
[Pubmed: 22574161]
| | 26. |
2012 May 8 |
Description and DNA barcoding of
Tipula (
Pterelachisus)
recondita sp. n. from the Palaearctic region (Diptera, Tipulidae)
Pilipenko, Salmela, Vesterinen
Zookeys 2012 May 8;(192):51-65. published online before print
Abstract
Tipula (Pterelachisus) recondita Pilipenko & Salmela, sp. n. is described. The new species is collected from two localities: Finland, Kittilä (North boreal ecoregion) and Russia, Primorski kray (Zone of temperate broadleaf and mixed forests). Although variation in the structure of male hypopygium between the Finnish and Russian populations is observed, DNA barcode sequences differ only by three nucleotides (0.2 % K2P distance), supporting presence of one widespread species. K2P minimum distances between the new species and 17 other species of the subgenus range from 5.3 to 15.8 % (mean 8.8 %). The new species is forest-dwelling, known from an old-growth herb-rich forest (Finland) and Quercus mongolica forest (Russia). The new species is perhaps closest to Tipula (Pterelachisus) imitator Alexander and in lesser extent to Tipula (Pterelachisus) pauli Mannheims; the inner gonostylus of both species are illustrated.
[Pubmed: 22639539]
| | 27. |
2012 Jun 7 |
The Coordination of Leaf Photosynthesis Links C and N Fluxes in C3 Plant Species
Maire, Martre, Kattge, Gastal, Esser, Fontaine, Soussana
PLoS One 2012 Jun 7;7(6). published online before print
Abstract
Photosynthetic capacity is one of the most sensitive parameters in vegetation models and its relationship to leaf nitrogen content links the carbon and nitrogen cycles. Process understanding for reliably predicting photosynthetic capacity is still missing. To advance this understanding we have tested across C3 plant species the coordination hypothesis, which assumes nitrogen allocation to photosynthetic processes such that photosynthesis tends to be co-limited by ribulose-1,5-bisphosphate (RuBP) carboxylation and regeneration. The coordination hypothesis yields an analytical solution to predict photosynthetic capacity and calculate area-based leaf nitrogen content (Na). The resulting model linking leaf photosynthesis, stomata conductance and nitrogen investment provides testable hypotheses about the physiological regulation of these processes. Based on a dataset of 293 observations for 31 species grown under a range of environmental conditions, we confirm the coordination hypothesis: under mean environmental conditions experienced by leaves during the preceding month, RuBP carboxylation equals RuBP regeneration. We identify three key parameters for photosynthetic coordination: specific leaf area and two photosynthetic traits (k3, which modulates N investment and is the ratio of RuBP carboxylation/oxygenation capacity () to leaf photosynthetic N content (Npa); and Jfac, which modulates photosynthesis for a given k3 and is the ratio of RuBP regeneration capacity (Jmax) to). With species-specific parameter values of SLA, k3 and Jfac, our leaf photosynthesis coordination model accounts for 93% of the total variance in Na across species and environmental conditions. A calibration by plant functional type of k3 and Jfac still leads to accurate model prediction of Na, while SLA calibration is essentially required at species level. Observed variations in k3 and Jfac are partly explained by environmental and phylogenetic constraints, while SLA variation is partly explained by phylogeny. These results open a new avenue for predicting photosynthetic capacity and leaf nitrogen content in vegetation models.
[Pubmed: 22685562]
| | 28. |
2012 May 17 |
The Nearctic-Caribbean species
Leptotrachelus dorsalis (Fabricius, 1801): Larval descriptions with a diagnosis of immature Ctenodactylini and natural history notes on the genus and tribe (Coleoptera, Carabidae)
Erwin, White
Zookeys 2012 May 17;(194):17-32. published online before print
Abstract
Adults and larvae of Leptotrachelus dorsalis (Fabricius), the Sugarcane Savior Beetle, live in association with grasses, the larvae in the appressed leaf axils. Both adult and larval Leptotrachelus dorsalis eat larvae of the Sugarcane Borer, Diatraea saccharalis (Fabricius), and perhaps other insects living in the confines of the leaf sheaths of that and other grass-like species. The geographic range of Leptotrachelus dorsalis extends from Kansas in the west to the Atlantic seaboard, north as far as Ontario, Canada and south to Cuba; it is an eastern species of North America and the Caribbean. Larval character attributes that are shared with a related ctenodactyline, Askalaphium depressum (Bates), provide a preliminary basis for characterization of the immatures of tribe Ctenodactylini.
[Pubmed: 22679382]
| | 29. |
2012 May 2 |
NADP-Dependent Isocitrate Dehydrogenase from Arabidopsis Roots Contributes in the Mechanism of Defence against the Nitro-Oxidative Stress Induced by Salinity
Leterrier, Barroso, Valderrama, Palma, Corpas
ScientificWorldJournal 2012 May 2;2012. published online before print
Abstract
NADPH regeneration appears to be essential in the mechanism of plant defence against oxidative stress. Plants contain several NADPH-generating dehydrogenases including isocitrate dehydrogenase (NADP-ICDH), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and malic enzyme (ME). In Arabidopsis seedlings grown under salinity conditions (100 mM NaCl) the analysis of physiological parameters, antioxidant enzymes (catalase and superoxide dismutase) and content of superoxide radical (O2 ∙−), nitric oxide (NO), and peroxynitrite (ONOO−) indicates a process of nitro-oxidative stress induced by NaCl. Among the analysed NADPH-generating dehydrogenases under salinity conditions, the NADP-ICDH showed the maximum activity mainly attributable to the root NADP-ICDH. Thus, these data provide new insights on the relevance of the NADP-ICDH which could be considered as a second barrier in the mechanism of response against the nitro-oxidative stress generated by salinity.
[Pubmed: 22649311]
| | 30. |
2012 Jun 6 |
DNA Barcoding the Native Flowering Plants and Conifers of Wales
de Vere, Rich, Ford, Trinder, Long, Moore, Satterthwaite, Davies, Allainguillaume, Ronca, Tatarinova, Garbett, Walker, Wilkinson
PLoS One 2012 Jun 6;7(6). published online before print
Abstract
We present the first national DNA barcode resource that covers the native flowering plants and conifers for the nation of Wales (1143 species). Using the plant DNA barcode markers rbcL and matK, we have assembled 97.7% coverage for rbcL, 90.2% for matK, and a dual-locus barcode for 89.7% of the native Welsh flora. We have sampled multiple individuals for each species, resulting in 3304 rbcL and 2419 matK sequences. The majority of our samples (85%) are from DNA extracted from herbarium specimens. Recoverability of DNA barcodes is lower using herbarium specimens, compared to freshly collected material, mostly due to lower amplification success, but this is balanced by the increased efficiency of sampling species that have already been collected, identified, and verified by taxonomic experts. The effectiveness of the DNA barcodes for identification (level of discrimination) is assessed using four approaches: the presence of a barcode gap (using pairwise and multiple alignments), formation of monophyletic groups using Neighbour-Joining trees, and sequence similarity in BLASTn searches. These approaches yield similar results, providing relative discrimination levels of 69.4 to 74.9% of all species and 98.6 to 99.8% of genera using both markers. Species discrimination can be further improved using spatially explicit sampling. Mean species discrimination using barcode gap analysis (with a multiple alignment) is 81.6% within 10×10 km squares and 93.3% for 2×2 km squares. Our database of DNA barcodes for Welsh native flowering plants and conifers represents the most complete coverage of any national flora, and offers a valuable platform for a wide range of applications that require accurate species identification.
[Pubmed: 22701588]
| | 31. |
2012 Jun 4 |
The Impact of Root Temperature on Photosynthesis and Isoprene Emission in Three Different Plant Species
Medori, Michelini, Nogues, Loreto, Calfapietra
ScientificWorldJournal 2012 Jun 4;2012. published online before print
Abstract
Most of the perennial plant species, particularly trees, emit volatile organic compounds (BVOCs) such as isoprene and monoterpenes, which in several cases have been demonstrated to protect against thermal shock and more generally against oxidative stress. In this paper, we show the response of three strong isoprene emitter species, namely, Phragmites australis, Populus x euramericana, and Salix phylicifolia exposed to artificial or natural warming of the root system in different conditions. This aspect has not been investigated so far while it is well known that warming the air around a plant stimulates considerably isoprene emission, as also shown in this paper. In the green house experiments where the warming corresponded with high stress conditions, as confirmed by higher activities of the main antioxidant enzymes, we found that isoprene uncoupled from photosynthesis at a certain stage of the warming treatment and that even when photosynthesis approached to zero isoprene emission was still ongoing. In the field experiment, in a typical cold-limited environment, warming did not affect isoprene emission whereas it increased significantly CO2 assimilation. Our findings suggest that the increase of isoprene could be a good marker of heat stress, whereas the decrease of isoprene a good marker of accelerated foliar senescence, two hypotheses that should be better investigated in the future.
[Pubmed: 22701360]
| | 32. |
2012 Jun 19 |
Occupational cancer in Britain
Brown, Darnton, Fortunato, Rushton,
Br J Cancer 2012 Jun 19;107(S1):S56-S70.
[Pubmed: 22710680]
| | 33. |
2012 Jun 29 |
High-Resolution Coproecology: Using Coprolites to Reconstruct the Habits and Habitats of New Zealand’s Extinct Upland Moa (Megalapteryx didinus)
Wood, Wilmshurst, Wagstaff, Worthy, Rawlence, Cooper
PLoS One 2012 Jun 29;7(6). published online before print
Abstract
Knowledge about the diet and ecology of extinct herbivores has important implications for understanding the evolution of plant defence structures, establishing the influences of herbivory on past plant community structure and composition, and identifying pollination and seed dispersal syndromes. The flightless ratite moa (Aves: Dinornithiformes) were New Zealand’s largest herbivores prior to their extinction soon after initial human settlement. Here we contribute to the knowledge of moa diet and ecology by reporting the results of a multidisciplinary study of 35 coprolites from a subalpine cave (Euphrates Cave) on the South Island of New Zealand. Ancient DNA analysis and radiocarbon dating revealed the coprolites were deposited by the extinct upland moa (Megalapteryx didinus), and span from at least 6,368±31 until 694±30 14C years BP; the approximate time of their extinction. Using pollen, plant macrofossil, and ancient DNA analyses, we identified at least 67 plant taxa from the coprolites, including the first evidence that moa fed on the nectar-rich flowers of New Zealand flax (Phormium) and tree fuchsia (Fuchsia excorticata). The plant assemblage from the coprolites reflects a highly-generalist feeding ecology for upland moa, including browsing and grazing across the full range of locally available habitats (spanning southern beech (Nothofagus) forest to tussock (Chionochloa) grassland). Intact seeds in the coprolites indicate that upland moa may have been important dispersal agents for several plant taxa. Plant taxa with putative anti-browse adaptations were also identified in the coprolites. Clusters of coprolites (based on pollen assemblages, moa haplotypes, and radiocarbon dates), probably reflect specimens deposited at the same time by individual birds, and reveal the necessity of suitably large sample sizes in coprolite studies to overcome potential biases in diet interpretation.
[Pubmed: 22768206]
| | 34. |
2012 Jun 27 |
Molecular Identification of Commercialized Medicinal Plants in Southern Morocco
Kool, de Boer, Krüger, Rydberg, Abbad, Björk, Martin
PLoS One 2012 Jun 27;7(6). published online before print
Abstract
Medicinal plant trade is important for local livelihoods. However, many medicinal plants are difficult to identify when they are sold as roots, powders or bark. DNA barcoding involves using a short, agreed-upon region of a genome as a unique identifier for species– ideally, as a global standard.
[Pubmed: 22761800]
| | 35. |
2012 Jun 29 |
What Is the Impact of Impatiens parviflora on Diversity and Composition of Herbal Layer Communities of Temperate Forests?
Hejda
PLoS One 2012 Jun 29;7(6). published online before print
Abstract
The aim was to estimate the impacts of invasive Impatiens parviflora on forests’ herbal layer communities. A replicated Before-After-Control-Impact field experiment and comparisons with adjacent uninvaded plots were used. The alien’s impact on species richness was tested using hierarchical generalized mixed effect models with Poisson error structure. Impact on species composition was tested using multivariate models (DCA, CCA, RDA) and Monte-Carlo permutation tests. Removal plots did not differ in native species richness from neither invaded nor adjacent uninvaded plots, both when the treatment’s main effect or its interaction with sampling time was tested (Chi2 = 0.4757, DF = 2, p = 0.7883; Chi2 = 7.229, DF = 8, p = 0.5121 respectively). On the contrary, ordination models revealed differences in the development of plots following the treatments (p = 0.034) with the invaded plots differing from the adjacent uninvaded (p = 0.002). Impatiens parviflora is highly unlikely to impact native species richness of invaded communities, which may be associated with its limited ability to create a dense canopy, a modest root system or the fact the I. parviflora does not represent a novel and distinctive dominant to the invaded communities. Concerning its potential impacts on species composition, the presence of native clonal species (Athyrium filix-femina, Dryopteris filix-mas, Fragaria moschata, Luzula luzuloides, Poa nemoralis) on the adjacent uninvaded plots likely makes them different from the invaded plots. However, these competitive and strong species are more likely to prevent the invasion of I. parviflora on the adjacent uninvaded plots rather than being themselves eliminated from the invaded communities.
[Pubmed: 22768091]
| | 36. |
2012 Jul 3 |
Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand
Wagstaff, Clarkson
PhytoKeys 2012 Jul 3;(13):39-79. published online before print
Abstract
The genus Empodisma comprises two species that are ecologically important in wetland habitats. Empodisma gracillimum is restricted to south-western Australia, whereas Empodisma minus is found in Tasmania, eastern Australia and New Zealand. We sequenced three cpDNA genes for 15 individuals of Empodisma sampled from throughout the range of the species. The results support an Australian origin for Empodisma sometime during the late Oligocene to early Miocene with more recent dispersal, colonization and diversification in New Zealand. We recovered six genetically distinct maternal lineages: three Empodisma gracillimum haplotypes corresponding to the three accessions in our analysis, a wide-ranging Empodisma minus haplotype found in eastern Australia and Tasmania, an Empodisma minus haplotype found in New Zealand from Stewart Island to approximately 38° S latitude on the North Island, and a distinct haplotype restricted to the North Island of New Zealand north of 38° S latitude. The Eastern Australian and New Zealand haplotypes of Empodisma minus were supported by only one cpDNA gene, and we felt the relatively minor morphological differences and the small amount of genetic divergence did not warrant taxonomic recognition. However, we recommend that the northern New Zealand haplotype should be recognized as the new species Empodisma robustum and provide descriptions and a key to the species of Empodisma. Monophyly of Empodisma robustum is supported by all three cpDNA genes. Empodisma robustum can be distinguished from Empodisma gracillimum and Empodisma minus by its robust growth stature and distinct ecology. It is typically eliminated by fire and re-establishes by seed (seeder strategy), whereas Empodisma minus and Empodisma gracillimum regrow after fire (sprouter strategy).
[Pubmed: 22787426]
| | 37. |
2012 Jun 15 |
The genus Cladosporium
Bensch, Braun, Groenewald, Crous
Stud Mycol 2012 Jun 15;72(1):1-401.
Abstract
A monographic revision of the hyphomycete genus Cladosporium s. lat. (Cladosporiaceae, Capnodiales) is presented. It includes a detailed historic overview of Cladosporium and allied genera, with notes on their phylogeny, systematics and ecology. True species of Cladosporium s. str. (anamorphs of Davidiella), are characterised by having coronate conidiogenous loci and conidial hila, i.e., with a convex central dome surrounded by a raised periclinal rim. Recognised species are treated and illustrated with line drawings and photomicrographs (light as well as scanning electron microscopy). Species known from culture are described in vivo as well as in vitro on standardised media and under controlled conditions. Details on host range/substrates and the geographic distribution are given based on published accounts, and a re-examination of numerous herbarium specimens. Various keys are provided to support the identification of Cladosporium species in vivo and in vitro. Morphological datasets are supplemented by DNA barcodes (nuclear ribosomal RNA gene operon, including the internal transcribed spacer regions ITS1 and ITS2, the 5.8S nrDNA, as well as partial actin and translation elongation factor 1-α gene sequences) diagnostic for individual species. In total 993 names assigned to Cladosporium s. lat., including Heterosporium (854 in Cladosporium and 139 in Heterosporium), are treated, of which 169 are recognized in Cladosporium s. str. The other taxa are doubtful, insufficiently known or have been excluded from Cladosporium in its current circumscription and re-allocated to other genera by the authors of this monograph or previous authors.
[Pubmed: 22815589]
| | 38. |
2012 Jul 5 |
Bringing Together Evolution on Serpentine and Polyploidy: Spatiotemporal History of the Diploid-Tetraploid Complex of Knautia arvensis (Dipsacaceae)
Kolář, Fér, Štech, Trávníček, Dušková, Schönswetter, Suda
PLoS One 2012 Jul 5;7(7). published online before print
Abstract
Polyploidization is one of the leading forces in the evolution of land plants, providing opportunities for instant speciation and rapid gain of evolutionary novelties. Highly selective conditions of serpentine environments act as an important evolutionary trigger that can be involved in various speciation processes. Whereas the significance of both edaphic speciation on serpentine and polyploidy is widely acknowledged in plant evolution, the links between polyploid evolution and serpentine differentiation have not yet been examined. To fill this gap, we investigated the evolutionary history of the perennial herb Knautia arvensis (Dipsacaceae), a diploid-tetraploid complex that exhibits an intriguing pattern of eco-geographic differentiation. Using plastid DNA sequencing and AFLP genotyping of 336 previously cytotyped individuals from 40 populations from central Europe, we unravelled the patterns of genetic variation among the cytotypes and the edaphic types. Diploids showed the highest levels of genetic differentiation, likely as a result of long term persistence of several lineages in ecologically distinct refugia and/or independent immigration. Recurrent polyploidization, recorded in one serpentine island, seems to have opened new possibilities for the local serpentine genotype. Unlike diploids, the serpentine tetraploids were able to escape from the serpentine refugium and spread further; this was also attributable to hybridization with the neighbouring non-serpentine tetraploid lineages. The spatiotemporal history of K. arvensis allows tracing the interplay of polyploid evolution and ecological divergence on serpentine, resulting in a complex evolutionary pattern. Isolated serpentine outcrops can act as evolutionary capacitors, preserving distinct karyological and genetic diversity. The serpentine lineages, however, may not represent evolutionary ‘dead-ends’ but rather dynamic systems with a potential to further influence the surrounding populations, e.g., via independent polyplodization and hybridization. The complex eco-geographical pattern together with the incidence of both primary and secondary diploid-tetraploid contact zones makes K. arvensis a unique system for addressing general questions of polyploid research.
[Pubmed: 22792207]
| | 39. |
2012 Jul 26 |
Detritus Quality Controls Macrophyte Decomposition under Different Nutrient Concentrations in a Eutrophic Shallow Lake, North China
Li, Cui, Yang, Tian, Lan, Wang, Han
PLoS One 2012 Jul 26;7(7). published online before print
Abstract
Macrophyte decomposition is important for carbon and nutrient cycling in lake ecosystems. Currently, little is known about how this process responds to detritus quality and water nutrient conditions in eutrophic shallow lakes in which incomplete decomposition of detritus accelerates the lake terrestrialization process. In this study, we investigated the effects of detritus quality and water nutrient concentrations on macrophyte decomposition in Lake Baiyangdian, China, by analyzing the decomposition of three major aquatic plants at three sites with different pollution intensities (low, medium, and high pollution sites). Detritus quality refers to detritus nutrient contents as well as C∶N, C∶P, and N∶P mass ratios in this study. Effects of detritus mixtures were tested by combining pairs of representative macrophytes at ratios of 75∶25, 50∶50 and 25∶75 (mass basis). The results indicate that the influence of species types on decomposition was stronger than that of site conditions. Correlation analysis showed that mass losses at the end of the experimental period were significantly controlled by initial detritus chemistry, especially by the initial phosphorus (P) content, carbon to nitrogen (C∶N), and carbon to phosphorus (C∶P) mass ratios in the detritus. The decomposition processes were also influenced by water chemistry. The NO3-N and NH4-N concentrations in the lake water retarded detritus mass loss at the low and high pollution sites, respectively. Net P mineralization in detritus was observed at all sites and detritus P release at the high pollution site was slower than at the other two sites. Nonadditive effects of mixtures tended to be species specific due to the different nutrient contents in each species. Results suggest that the nonadditive effects varied significantly among different sites, indicating that interactions between the detritus quality in species mixtures and site water chemistry may be another driver controlling decomposition in eutrophic shallow lakes.
[Pubmed: 22848699]
| | 40. |
2012 Jul 17 |
Measures of Light in Studies on Light-Driven Plant Plasticity in Artificial Environments
Niinemets, Keenan
Front Plant Sci 2012 Jul 17;3. published online before print
Abstract
Within-canopy variation in light results in profound canopy profiles in foliage structural, chemical, and physiological traits. Studies on within-canopy variations in key foliage traits are often conducted in artificial environments, including growth chambers with only artificial light, and greenhouses with and without supplemental light. Canopy patterns in these systems are considered to be representative to outdoor conditions, but in experiments with artificial and supplemental lighting, the intensity of artificial light strongly deceases with the distance from the light source, and natural light intensity in greenhouses is less than outdoors due to limited transmittance of enclosure walls. The implications of such changes in radiation conditions on canopy patterns of foliage traits have not yet been analyzed. We developed model-based methods for retrospective estimation of distance vs. light intensity relationships, for separation of the share of artificial and natural light in experiments with combined light and for estimation of average enclosure transmittance, and estimated daily integrated light at the time of sampling (Qint,C), at foliage formation (Qint,G), and during foliage lifetime (Qint,av). The implications of artificial light environments were analyzed for altogether 25 studies providing information on within-canopy gradients of key foliage traits for 70 species × treatment combinations. Across the studies with artificial light, Qint,G for leaves formed at different heights in the canopy varied from 1.8- to 6.4-fold due to changing the distance between light source and growing plants. In experiments with combined lighting, the share of natural light at the top of the plants varied threefold, and the share of natural light strongly increased with increasing depth in the canopy. Foliage nitrogen content was most strongly associated with Qint,G, but photosynthetic capacity with Qint,C, emphasizing the importance of explicit description of light environment during foliage lifetime. The reported and estimated transmittances of enclosures varied between 0.27 and 0.85, and lack of consideration of the reduction of light compared with outdoor conditions resulted in major underestimation of foliage plasticity to light. The study emphasizes that plant trait vs. light relationships in artificial systems are not directly comparable to natural environments unless modifications in lighting conditions in artificial environments are taken into account.
[Pubmed: 22822407]
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