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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. |
2010 Dec 09 |
The start-to-end chemometric image processing of 2D thin-layer videoscans.
Komsta Ł, Cieśla Ł, Bogucka-Kocka A, Józefczyk A, Kryszeń J, Waksmundzka-Hajnos M
J Chromatogr A. 2011 May 13;1218(19):2820-5. Epub 2010 Dec 09.
Abstract
The purpose of the research was to recommend a unified procedure of image preprocessing of 2D thin layer videoscans for further supervised or unsupervised chemometric analysis. All work was done with open source software. The videoscans saved as JPG files underwent the following procedures: denoising using a median filter, baseline removal with the rollerball algorithm and nonlinear warping using spline functions. The application of the proposed procedure enabled filtration of random difference between images (background intensity changes and spatial differences of the spots location). After the preprocessing only spot intensities have an influence on the performed PCA or other techniques. The proposed technique was successfully applied to recognize the differences between three Carex species from the 2D videoscans of the extracts. The proposed solution may be of value for the any chemometric task--both unsupervised and supervised.
[Pubmed: 21183184]
| | 5. |
2010 Sep 14 |
Responses to mineral nutrient availability and heterogeneity in physiologically integrated sedges from contrasting habitats.
D'Hertefeldt T, Falkengren-Grerup U, Jónsdóttir IS
Plant Biol (Stuttg). 2011 May;13(3):483-92. Epub 2010 Sep 14.
Abstract
Clonal plants from poor habitats benefit less from morphologically plastic responses to heterogeneity than plants from more productive sites. In addition, physiological integration has been suggested to either increase or decrease the foraging efficiency of clonal plants. We tested the capacity for biomass production and morphological response in two closely related, rhizomatous species from habitats that differ in resource availability, Carex arenaria (from poor sand dunes) and C. disticha (from nutrient-richer, moister habitats). We expected lower total biomass production and reduced morphological plasticity in C. arenaria, and that both species would produce more ramets in high nutrient patches, either in response to signals transported through physiological integration, or by locally determined responses to nutrient availability. To investigate mineral nutrient heterogeneity, plants were grown in boxes divided into two compartments with homogeneous or heterogeneous supply of high (H) or low (L) nutrient levels, resulting in four treatments, H-H, H-L, L-H and L-L. Both C. arenaria and C. disticha produced similar biomass in high nutrient treatments. C. disticha responded to high nutrients by increased biomass production and branching of the young parts and by altering root:shoot ratio and rhizome lengths, while C. arenaria showed localised responses to high nutrients in terms of local biomass and branch production in high nutrient patches. The results demonstrated that although it has a conservative morphology, C. arenaria responded to nutrient heterogeneity through morphological plasticity. An analysis of costs and benefits of integration on biomass production showed that young ramets of both species benefited significantly from physiological integration, but no corresponding costs were found. This suggests that plants from resource-poor but dynamic habitats like sand dunes respond morphologically to high nutrient patches. The two species responded to nutrient heterogeneity in different traits, and this is discussed in terms of local and distant signalling of plant status.
[Pubmed: 21489099]
| | 6. |
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]
| | 7. |
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]
| | 8. |
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]
| | 9. |
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]
| | 10. |
|
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]
| | 11. |
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]
| | 12. |
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]
| | 13. |
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]
| | 14. |
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]
| | 15. |
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]
| | 16. |
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]
| | 17. |
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]
| | 18. |
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]
| | 19. |
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]
| | 20. |
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]
| | 21. |
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]
| | 22. |
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]
| | 23. |
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]
| | 24. |
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]
| | 25. |
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]
| | 26. |
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]
| | 27. |
2012 Jun 19 |
Occupational cancer in Britain.
Chen Y, Osman J
Br. J. Cancer. 2012 Jun 19;107 Suppl 1:S104-8.
Abstract
Although only a relatively small proportion of cancer is attributable to occupational exposure to carcinogenic agents, the estimated number of deaths due to occupational cancer is high when compared to other deaths due to work-related ill health and injury. However, risk from occupational exposure to carcinogens can be minimised through proportionate but effective risk management. The Health and Safety Executive (HSE) is the regulator of workplace health and safety in Great Britain. As part of its aim to reduce ill health arising from failures to control properly exposure to hazards at work, HSE commissioned the research presented elsewhere in this supplement to enable it to identify priorities for preventing occupational cancer. The research has shown that occupational cancer remains a key health issue and that low-level exposure of a large number of workers to carcinogens is important. The finding that a small number of carcinogens have been responsible for the majority of the burden of occupational cancer provides key evidence in the development of priorities for significant reduction of occupational cancer. Although the research presented in this supplement reflects the consequences of past exposures to carcinogens, occupational cancer remains a problem. The potential for exposure to the agents considered in this research is still present in the workplace and the findings are relevant to prevention of future disease. In this article, the principle approaches for risk reduction are described. It provides supporting information on some of the initiatives already being undertaken, or those being put in place, to reduce occupational cancer in Great Britain. The need also for systematic collection of exposure information and the importance of raising awareness and changing behaviours are discussed.
[Pubmed: 22710673]
| | 28. |
2012 Jul 16 |
Anthracoidea caricis-meadii is a new North American smut fungus on Carex sect. Paniceae.
Savchenko KG, Lutz M, Piatek M, Heluta V, Nevo E
Mycologia. 2012 Jul 16; [Epub ahead of print]
Abstract
The morphology and phylogeny of Anthracoidea on Carex meadii (sect. Paniceae) collected in Illinois, Iowa, and Wisconsin, U.S.A., were studied using light microscopy, scanning electron microscopy, and LSU rDNA sequence analyses. As a result, A. caricis-meadii sp. nov. is described. The fungus differs morphologically from Anthracoidea laxae and A. paniceae, which also occur on sedges from the section Paniceae. Molecular analyses support the placement of the latter species, and Anthracoidea caricis-meadii in different phylogenetic lineages. Because of morphological discrepancies reported in the literature, A. laxae and A. paniceae are also described and illustrated based on re-examination of respective holotype and isotype specimens.
[Pubmed: 22802390]
| | 29. |
2012 |
Evaluating Escherichia coli removal performance in stormwater biofilters: a laboratory-scale study.
Chandrasena GI, Deletic A, Ellerton J, McCarthy DT
Water Sci. Technol. 2012;66(5):1132-8.
Abstract
Biofilters are common, low energy technologies used for the treatment of urban stormwater. While they have shown promising results for the removal of stormwater microorganisms, certain factors affect their performance. Hence, this study investigated the effects of particle-microbial interaction, inflow concentration, antecedent microbial levels and plant species on microbial removal capacity. A biofilter column study was set up to evaluate removal performance and a sequential filtration procedure was used to estimate microbial partitioning. The columns were dosed with different concentrations of free phase Escherichia coli only and E. coli mixed with stormwater sediment. Results indicate that the microbial removal is significantly affected by inflow concentration and antecedent microbial levels. Leaching was only observed when a relatively low inflow concentration event occurred within a short period after a very high inflow concentration event. Finally, Lomandra longifolia showed better removal compared with Carex appressa.
[Pubmed: 22797244]
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