|
| | 1. |
1997 Sep 2 |
Reorganization of an arid ecosystem in response to recent climate change
Brown, Valone, Curtin
Proc Natl Acad Sci U S A 1997 Sep 2;94(18):9729-9733.
Abstract
Natural ecosystems contain many individuals and species interacting with each other and with their abiotic environment. Such systems can be expected to exhibit complex dynamics in which small perturbations can be amplified to cause large changes. Here, we document the reorganization of an arid ecosystem that has occurred since the late 1970s. The density of woody shrubs increased 3-fold. Several previously common animal species went locally extinct, while other previously rare species increased. While these changes are symptomatic of desertification, they were not caused by livestock grazing or drought, the principal causes of historical desertification. The changes apparently were caused by a shift in regional climate: since 1977 winter precipitation throughout the region was substantially higher than average for this century. These changes illustrate the kinds of large, unexpected responses of complex natural ecosystems that can occur in response to both natural perturbations and human activities.
[Pubmed: 11038570]
| | 2. |
2006 Oct 22 |
Herbivory: effects on plant abundance, distribution and population growth
Maron, Crone
Proc Biol Sci 2006 Oct 22;273(1601):2575-2584.
Abstract
Plants are attacked by many different consumers. A critical question is how often, and under what conditions, common reductions in growth, fecundity or even survival that occur due to herbivory translate to meaningful impacts on abundance, distribution or dynamics of plant populations. Here, we review population-level studies of the effects of consumers on plant dynamics and evaluate: (i) whether particular consumers have predictably more or less influence on plant abundance, (ii) whether particular plant life-history types are predictably more vulnerable to herbivory at the population level, (iii) whether the strength of plant–consumer interactions shifts predictably across environmental gradients and (iv) the role of consumers in influencing plant distributional limits. Existing studies demonstrate numerous examples of consumers limiting local plant abundance and distribution. We found larger effects of consumers on grassland than woodland forbs, stronger effects of herbivory in areas with high versus low disturbance, but no systematic or unambiguous differences in the impact of consumers based on plant life-history or herbivore feeding mode. However, our ability to evaluate these and other patterns is limited by the small (but growing) number of studies in this area. As an impetus for further study, we review strengths and challenges of population-level studies, such as interpreting net impacts of consumers in the presence of density dependence and seed bank dynamics.
[Pubmed: 17002942]
| | 3. |
2008 Oct 9 |
Rapid Chromosome Evolution in Recently Formed Polyploids in Tragopogon (Asteraceae)
Lim, Soltis, Soltis, Tate, Matyasek, Srubarova, Kovarik, Pires, Xiong, Leitch
PLoS ONE 2008 Oct 9;3(10). published online before print
Abstract
Polyploidy, frequently termed “whole genome duplication”, is a major force in the evolution of many eukaryotes. Indeed, most angiosperm species have undergone at least one round of polyploidy in their evolutionary history. Despite enormous progress in our understanding of many aspects of polyploidy, we essentially have no information about the role of chromosome divergence in the establishment of young polyploid populations. Here we investigate synthetic lines and natural populations of two recently and recurrently formed allotetraploids Tragopogon mirus and T. miscellus (formed within the past 80 years) to assess the role of aberrant meiosis in generating chromosomal/genomic diversity. That diversity is likely important in the formation, establishment and survival of polyploid populations and species.
[Pubmed: 18843372]
| | 4. |
1995 Jan |
Comparative antimicrobial study of the resinous exudates of some Chilean Haplopappus (Asteraceae).
Urzúa A, Torres R, Muñoz M, Palacios Y
J Ethnopharmacol. 1995 Jan;45(1):71-4.
Abstract
The antimicrobiol properties and preliminary chemical information of the resinous exudates from twigs and leaves of nine Haplopappus species from Chile: H. diplopappus; H. anthylloides; H. schumannii; H. cuneifolius; H. velutinus; H. uncinatus; H. multifolius, H. illinitus and H. foliosus are presented. The results show that those species of genus Haplopappus share similar antimicrobial activities although they differ dramatically in the chemical composition.
[Pubmed: 7739230]
| | 5. |
1999 Apr 5 |
Evidence for a Relatively Random Array of Human Chromosomes on the Mitotic Ring
Allison, Nestor
J Cell Biol 1999 Apr 5;145(1):1-14.
Abstract
We used fluorescence in situ hybridization (FISH) to study the positions of human chromosomes on the mitotic rings of cultured human lymphocytes, MRC-5 fibroblasts, and CCD-34Lu fibroblasts. The homologous chromosomes of all three cell types had relatively random positions with respect to each other on the mitotic rings of prometaphase rosettes and anaphase cells. Also, the positions of the X and Y chromosomes, colocalized with the somatic homologues in male cells, were highly variable from one mitotic ring to another. Although random chromosomal positions were found in different pairs of CCD-34Lu and MRC-5 late-anaphases, the separations between the same homologous chromosomes in paired late-anaphase and telophase chromosomal masses were highly correlated. Thus, although some loose spatial associations of chromosomes secondary to interphase positioning may exist on the mitotic rings of some cells, a fixed order of human chromosomes and/or a rigorous separation of homologous chromosomes on the mitotic ring are not necessary for normal mitosis. Furthermore, the relative chromosomal positions on each individual metaphase plate are most likely carried through anaphase into telophase.
[Pubmed: 10189364]
| | 6. |
2000 Jun 20 |
The role of genetic and genomic attributes in the success
of polyploids
Soltis, Soltis
Proc Natl Acad Sci U S A 2000 Jun 20;97(13):7051-7057.
Abstract
In 1950, G. Ledyard Stebbins devoted two chapters of his book
Variation and Evolution in Plants (Columbia Univ. Press,
New York) to polyploidy, one on occurrence and nature and one on
distribution and significance. Fifty years later, many of the questions
Stebbins posed have not been answered, and many new questions have
arisen. In this paper, we review some of the genetic attributes of
polyploids that have been suggested to account for the tremendous
success of polyploid plants. Based on a limited number of studies, we
conclude: (i) Polyploids, both individuals and
populations, generally maintain higher levels of heterozygosity than do
their diploid progenitors. (ii) Polyploids exhibit less
inbreeding depression than do their diploid parents and can therefore
tolerate higher levels of selfing; polyploid ferns indeed have higher
levels of selfing than do their diploid parents, but polyploid
angiosperms do not differ in outcrossing rates from their diploid
parents. (iii) Most polyploid species are polyphyletic,
having formed recurrently from genetically different diploid parents.
This mode of formation incorporates genetic diversity from multiple
progenitor populations into the polyploid “species”; thus,
genetic diversity in polyploid species is much higher than expected by
models of polyploid formation involving a single origin.
(iv) Genome rearrangement may be a common attribute of
polyploids, based on evidence from genome in situ
hybridization (GISH), restriction fragment length polymorphism (RFLP)
analysis, and chromosome mapping. (v) Several groups of
plants may be ancient polyploids, with large regions of homologous DNA.
These duplicated genes and genomes can undergo divergent evolution and
evolve new functions. These genetic and genomic attributes of
polyploids may have both biochemical and ecological benefits that
contribute to the success of polyploids in nature.
[Pubmed: 10860970]
| | 7. |
2003 Aug |
The influence of diet on faecal DNA amplification and sex identification in brown bears (Ursus arctos).
Murphy MA, Waits LP, Kendall KC
Mol. Ecol. 2003 Aug;12(8):2261-5.
Abstract
To evaluate the influence of diet on faecal DNA amplification, 11 captive brown bears (Ursus arctos) were placed on six restricted diets: grass (Trifolium spp., Haplopappus hirtus and Poa pratensis), alfalfa (Lupinus spp.), carrots (Daucus spp.), white-tailed deer (Odocoileus virginianus), blueberries (Vaccinium spp.) and salmon (Salmo spp.). DNA was extracted from 50 faecal samples of each restricted diet, and amplification of brown bear DNA was attempted for a mitochondrial DNA (mtDNA) locus and nuclear DNA (nDNA) locus. For mtDNA, no significant differences were observed in amplification success rates across diets. For nDNA, amplification success rates for salmon diet extracts were significantly lower than all other diet extracts (P < 0.001). To evaluate the accuracy of faecal DNA sex identification when female carnivores consume male mammalian prey, female bears were fed male white-tailed deer. Four of 10 extracts amplified, and all extracts were incorrectly scored as male due to amplification of X and Y-chromosome fragments. The potential biases highlighted in this study have broad implications for researchers using faecal DNA for individual and sex identification, and should be evaluated in other species.
[Pubmed: 12859644]
| | 8. |
1998 Mar 3 |
Plant genome values: How much do we know?
Bennett
Proc Natl Acad Sci U S A 1998 Mar 3;95(5):2011-2016.
Abstract
Plants are the basis of life on earth. We cannot overemphasize
their importance. The value of plant genome initiatives is
self-evident. The need is to identify priorities for action. The
angiosperm genome is highly variable, but the extent of this
variability is unknown. Uncertainties remain about the number of genes
and the number of species living. Many plants will become extinct
before they are discovered. We risk losing both genes and vital
information about plant uses. There are also major gaps in our
karyotypic knowledge. No chromosome count exists for >70% of
angiosperm species. DNA C values are known for only ≈1% of
angiosperms, a sample unrepresentative of the global flora. Researchers
reported new relationships between genome size and characters of major
interest for plant breeding and the environment and the need for more
data. In 1997, a Royal Botanic Gardens Kew workshop identified gaps and
planned international collaboration to fill them. An electronic version
of the Angiosperm DNA C value database also was published. Another
initiative, which will make a very significant contribution to the
conservation of plant genetic diversity on a global scale is Kew’s
Millennium Seed Bank, partly funded by the U.K. Millennium Commission,
celebrating the year 2000. Costing up to £80 million (£1 =
$1.62), its main aims are to collect and conserve the seed of almost
all of the U.K. spermatophyte flora by the year 2000, to collect and
conserve a further 10% of the world spermatophyte flora principally
from the drylands by 2009, and to provide a world class building as the
focus of this activity by 2000.
[Pubmed: 9482826]
| | 9. |
2009 Mar 04 |
Predator crypsis enhances behaviourally mediated indirect effects on plants by altering bumblebee foraging preferences.
Ings TC, Chittka L
Proc. Biol. Sci. 2009 Jun 7;276(1664):2031-6. Epub 2009 Mar 04.
Abstract
Predators of pollinators can influence pollination services and plant fitness via both consumptive (reducing pollinator density) and non-consumptive (altering pollinator behaviour) effects. However, a better knowledge of the mechanisms underlying behaviourally mediated indirect effects of predators is necessary to properly understand their role in community dynamics. We used the tripartite relationship between bumblebees, predatory crab spiders and flowers to ask whether behaviourally mediated effects are localized to flowers harbouring predators, or whether bees extend their avoidance to entire plant species. In a tightly controlled laboratory environment, bumblebees (Bombus terrestris) were exposed to a random mixture of equally rewarding yellow and white artificial flowers, but foraging on yellow flowers was very risky: bees had a 25 per cent chance of receiving a simulated predation attempt by 'robotic' crab spiders. As bees learnt to avoid 'dangerous' flowers, their foraging preferences changed and they began to visit fewer yellow flowers than expected by chance. Bees avoided spider-free yellow flowers as well as dangerous yellow flowers when spiders were more difficult to detect (the colour of yellow spiders was indistinguishable from that of yellow flowers). Therefore, this interaction between bee learning and predator crypsis could lead flower species harbouring cryptic predators to suffer from reduced reproductive success.
[Pubmed: 19324797]
| | 10. |
2003 Nov |
Argentinian plant extracts with relaxant effect on the smooth muscle of the corpus cavernosum of guinea pig.
Hnatyszyn O, Moscatelli V, Garcia J, Rondina R, Costa M, Arranz C, Balaszczuk A, Ferraro G, Coussio JD
Phytomedicine. 2003 Nov;10(8):669-74.
Abstract
Extracts of different polarity from Baccharis trimera, Haplopappus rigidus Huperzia saururus, Maytenus ilicifolia, Satureja parvifolia and Senecio eriophyton were tested for their relaxant activity on smooth muscle using L-phenylephrine precontracted strips of corpus cavernosum obtained from Guinea pigs. Highly significant and dose dependent results were obtained with the dichloromethane extracts of H. saururus (87% of relaxation at the dose of 10 mg/ml), S. parvifolia (95% of relaxation at 2.5 mg/ml) and S. eriophyton (94% of relaxation at 5 mg/ml). Similar effects were observed with the methanol extracts of H. saururus (88% of relaxation at 10 mg/ml) and S. parvifolia (84% of relaxation at 10 mg/ml). These results were comparable to those obtained with the dichloromethane and methanol extracts of the well known Mexican species Turnera diffusa. Moreover, the aqueous extract of H. rigidus and the aqueous and methanol extracts of S. eriophyton were highly effective in a dose dependent manner (more than 90% of relaxation at the dose of 10 mg/ml). Significant results, but with a lower overall relaxant activity (about 70% of relaxation at 10 mg/ml), could also be obtained with the aqueous extract of S. parvifolia and with the dichlormethane and methanol extracts of B. trimera and M. ilicifolia. The positive controls with Sildenafil citrate at doses ranging from 0.35 to 35 microg/ml yielded moderate effects (up to 46% of relaxation at 35 microg/ml). The effects observed in the present study seem to validate the folk medicinal use of the tested plants and open new ways in the search for natural products with vasodilatory effects.
[Pubmed: 14692728]
| | 11. |
2009 Sep 21 |
Antimicrobial and Antioxidant Activities of Plants from Northeast of Mexico.
Salazar-Aranda R, Pérez-López LA, López-Arroyo J, Alanís-Garza BA, Waksman de Torres N
Evid Based Complement Alternat Med. 2009 Sep 21; [Epub ahead of print]
Abstract
Traditional medicine has a key role in health care worldwide. Obtaining scientific information about the efficacy and safety of the plants from our region is one of the goals of our research group. In this report, 17 plants were selected and collected in different localities from northeast Mexico. The dried plants were separated into leaves, flowers, fruit, stems, roots and bark. Each part was extracted with methanol, and 39 crude extracts were prepared. The extracts were tested for their antimicrobial activity using three Gram-negative bacterial strains (Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii), three Gram-positive bacterial strains (Enterococcus faecalis and two Staphylococcus aureus strains), and seven clinically isolated yeasts (Candida albicans, C. krusei, C. tropicalis, C. parapsilosis and C. glabrata); their antioxidant activity was tested using a DPPH free radical assay. No activity against Gram-negative bacteria was observed with any extract up to the maximum concentration tested, 1000 mug ml(-1). We report here for the first time activity of Ceanothus coeruleus against S. aureus [flowers, minimal inhibitory concentration (MIC) 125 mug ml(-1)], C. glabrata (MICs 31.25 mug ml(-1)) and C. parapsilosis (MICs between 31.25 and 125 mug ml(-1)); Chrysanctinia mexicana against C. glabrata (MICs 31.25 mug ml(-1)); Colubrina greggii against E. faecalis (MICs 250 mug ml(-1)) and Cordia boissieri against C. glabrata (MIC 125 mug ml(-1)). Furthermore, this is the first report about antioxidant activity of extracts from Ceanothus coeruleus, Chrysanctinia mexicana, Colubrina greggii and Cyperus alternifolius. Some correlation could exist between antioxidant activity and antiyeast activity against yeasts in the species Ceanothus coeruleus, Schinus molle, Colubrina greggii and Cordia boissieri.
[Pubmed: 19770266]
| | 12. |
2008 Apr |
A Century of B Chromosomes in Plants: So What?
Jones, Viegas, Houben
Ann Bot (Lond) 2008 Apr;101(6):767-775.
Abstract
Supernumerary B chromosomes (Bs) are a major source of intraspecific variation in nuclear DNA amounts in numerous species of plants. They favour large genomes, and create polymorphisms for DNA variation in natural populations. By studying Bs we can gain useful knowledge about the organization, function and evolution of genomes. There are also significant biological questions concerning the origin and structural organization of Bs, and the way in which these selfish elements can establish themselves by exploiting the replicative machinery of their host genome nucleus.
[Pubmed: 17704238]
| | 13. |
2008 Apr |
A Strong Nucleotypic Effect on the Cell Cycle Regardless of Ploidy Level
Francis, Davies, Barlow
Ann Bot (Lond) 2008 Apr;101(6):747-757.
Abstract
In published studies, positive relationships between nucleotype and the duration of the mitotic cell cycle in angiosperms have been reported but the highest number of species analyzed was approx. 60. Here an analysis is presented of DNA C-values and cell cycle times in root apical meristems of angiosperms comprising 110 measurements, including monocots and eudicots within a set temperature range, and encompassing an approx. 290-fold variation in DNA C-values.
[Pubmed: 18339642]
| | 14. |
2008 May |
Karyotype Diversification and Evolution in Diploid and Polyploid South American Hypochaeris (Asteraceae) Inferred from rDNA Localization and Genetic Fingerprint Data
Weiss-Schneeweiss, Tremetsberger, Schneeweiss, Parker, Stuessy
Ann Bot 2008 May;101(7):909-918.
Abstract
Changes in chromosome structure and number play an important role in plant evolution. A system well-suited to studying different modes of chromosome evolution is the genus Hypochaeris (Asteraceae) with its centre of species' diversity in South America. All South American species uniformly have a chromosome base number of x = 4 combined with variation in rDNA number and distribution, and a high frequency of polyploidy. The aim of this paper is to assess directions and mechanisms of karyotype evolution in South American species by interpreting both newly obtained and previous data concerning rDNA localization in a phylogenetic context.
[Pubmed: 18285356]
| | 15. |
2008 Apr |
Biosystematics and Conservation: A Case Study with Two Enigmatic and Uncommon Species of Crassula from New Zealand
De Lange, Heenan, Keeling, Murray, Smissen, Sykes
Ann Bot (Lond) 2008 Apr;101(6):881-899.
Abstract
Crassula hunua and C. ruamahanga have been taxonomically controversial. Here their distinctiveness is assessed so that their taxonomic and conservation status can be clarified.
[Pubmed: 18055560]
| | 16. |
2005 Nov 28 |
A new antibacterial clerodane diterpenoid from the resinous exudate of Haplopappus uncinatus.
Urzúa A, Jara F, Tojo E, Wilkens M, Mendoza L, Rezende MC
J Ethnopharmacol. 2006 Jan 16;103(2):297-301. Epub 2005 Nov 28.
Abstract
The antibacterial activity of Haplopappus uncinatus is attributed to a new clerodane diterpenoid, 18-acetoxy-cis-cleroda-3-en-15-oic acid (10 betaH, 16 xi 19 beta, 17beta, 20 alpha form) (1), isolated as a major component from the resinous exudates of its twigs and leaves, together with the inactive 3,5-dihydroxy-6,7,3',4'-tetramethoxyflavone, n-alkanes and a few sesquiterpenoids.
[Pubmed: 16310995]
| | 17. |
2001 May |
Antibacterial activity of the resinous exudates from Haplopappus uncinatus and Haplopappus foliosus.
Urzúa A, Mendoza L
Fitoterapia. 2001 May;72(4):418-20.
Abstract
The antibacterial activities of the resinous exudates from Haplopappus uncinatus and H. foliosus are reported. The results provide a justification to the traditional use of the resinous exudates of Haplopappus spp as an antiseptic.
[Pubmed: 11395268]
| | 18. |
2000 Jun 1 |
Comparative chemical composition of the resinous exudates from Haplopappus foliosus and H. uncinatus.
Urzúa AA, Andrade L, Jara F
Biochem. Syst. Ecol. 2000 Jun 1;28(5):491-493.
[Pubmed: 10725607]
| | 19. |
2008 Jul 10 |
Cytological investigation of Haplopappus gracilis (Nutt.) Gray: 5-methylcytosine-rich regions, fluorochrome banding and chromatin sensitivity to DNase I digestion.
Ruffini Castiglione M, Frediani M, Venora G, Cremonini R
Protoplasma. 2008;233(1-2):107-13. Epub 2008 Jul 10.
Abstract
Haplopappus gracilis (Nutt.) Gray, one of the five known higher plants with a chromosome number of 2n = 4, was studied from a cytological point of view. The chromosome complement of this species was characterized by means of automated karyotype analysis. Moreover, the DNA methylation pattern and fluorochrome banding were determined and compared with cytological data present in the literature. DNA methylation distribution along metaphase chromosomes involved all chromosome territories evidenced by C-banding. Other methylated bands correlated positively with aceto-orcein-positive heterochromatic portions and/or with late replicating bands and/or fluorochrome bands. Some methylated bands showed differences between homologous chromosomes. These bands belonged partly to certain heterochromatic domains and partly to intercalary sites not defined by other standard banding techniques. Differences between the homologues were also indicated by our DNA content data obtained after DNase I digestion.
[Pubmed: 18615238]
| | 20. |
2010 Feb 10 |
Asymmetrical conspecific seed-siring advantage between Silene latifolia and S. dioica.
Montgomery BR, Soper DM, Delph LF
Ann Bot. 2010 Feb 10; [Epub ahead of print]
Abstract
Background and Aims Silene dioica and S. latifolia experience only limited introgression despite overlapping flowering phenologies, geographical distributions, and some pollinator sharing. Conspecific pollen precedence and other reproductive barriers operating between pollination and seed germination may limit hybridization. This study investigates whether barriers at this stage contribute to reproductive isolation between these species and, if so, which mechanisms are responsible. Methods Pollen-tube lengths for pollen of both species in styles of both species were compared. Additionally, both species were pollinated with majority S. latifolia and majority S. dioica pollen mixes; then seed set, seed germination rates and hybridity of the resulting seedlings were determined using species-specific molecular markers. Key Results The longest pollen tubes were significantly longer for conspecific than heterospecific pollen in both species, indicating conspecific pollen precedence. Seed set but not seed germination was lower for flowers pollinated with pure heterospecific versus pure conspecific pollen. Mixed-species pollinations resulted in disproportionately high representation of nonhybrid offspring for pollinations of S. latifolia but not S. dioica flowers. Conclusions The finding of conspecific pollen precedence for pollen-tube growth but not seed siring in S. dioica flowers may be explained by variation in pollen-tube growth rates, either at different locations in the style or between leading and trailing pollen tubes. Additionally, this study finds a barrier to hybridization operating between pollination and seed germination against S. dioica but not S. latifolia pollen. The results are consistent with the underlying cause of this barrier being attrition of S. dioica pollen tubes or reduced success of heterospecifically fertilized ovules, rather than time-variant mechanisms. Post-pollination, pre-germination barriers to hybridization thus play a partial role in limiting introgression between these species.
[Pubmed: 20147372]
| | 21. |
2008 May 1 |
Influence of Microgravity Environment on Root Growth, Soluble Sugars, and Starch Concentration of Sweetpotato Stem Cuttings
Mortley, Bonsi, Hill, Morris, Williams, Davis, Williams, Levine, Petersen, Wheeler
J Am Soc Hortic Sci 2008 May 1;133(3):327-332.
Abstract
Because sweetpotato [Ipomoea batatas (L.) Lam.] stem cuttings regenerate very easily and quickly, a study of their early growth and development in microgravity could be useful to an understanding of morphological changes that might occur under such conditions for crops that are propagated vegetatively. An experiment was conducted aboard a U.S. Space Shuttle to investigate the impact of microgravity on root growth, distribution of amyloplasts in the root cells, and on the concentration of soluble sugars and starch in the stems of sweetpotatoes. Twelve stem cuttings of ‘Whatley/Loretan’ sweetpotato (5 cm long) with three to four nodes were grown in each of two plant growth units filled with a nutrient agarose medium impregnated with a half-strength Hoagland solution. One plant growth unit was flown on Space Shuttle Colombia for 5 days, whereas the other remained on the ground as a control. The cuttings were received within 2 h postflight and, along with ground controls, processed in ≈45 min. Adventitious roots were counted, measured, and fixed for electron microscopy and stems frozen for starch and sugar assays. Air samples were collected from the headspace of each plant growth unit for postflight determination of carbon dioxide, oxygen, and ethylene levels. All stem cuttings produced adventitious roots and growth was quite vigorous in both ground-based and flight samples and, except for a slight browning of some root tips in the flight samples, all stem cuttings appeared normal. The roots on the flight cuttings tended to grow in random directions. Also, stem cuttings grown in microgravity had more roots and greater total root length than ground-based controls. Amyloplasts in root cap cells of ground-based controls were evenly sedimented toward one end compared with a more random distribution in the flight samples. The concentration of soluble sugars, glucose, fructose, and sucrose and total starch concentration were all substantially greater in the stems of flight samples than those found in the ground-based samples. Carbon dioxide levels were 50% greater and oxygen marginally lower in the flight plants, whereas ethylene levels were similar and averaged less than 10 nL·L −1. Despite the greater accumulation of carbohydrates in the stems, and greater root growth in the flight cuttings, overall results showed minimal differences in cell development between space flight and ground-based tissues. This suggests that the space flight environment did not adversely impact sweetpotato metabolism and that vegetative cuttings should be an acceptable approach for propagating sweetpotato plants for space applications.
[Pubmed: 20186286]
| | 22. |
2009 Apr |
Antimicrobial clerodane diterpenoids from Microglossa angolensis Oliv. et Hiern.
Tamokou JD, Kuiate JR, Tene M, Tane P
Indian J Pharmacol. 2009 Apr;41(2):60-3.
Abstract
OBJECTIVE: To identify the antimicrobial components present in Microglossa angolensis following fractionation of the methylene chloride extract of the aerial part of this plant. MATERIALS AND METHODS: The plant was dried and extracted by percolation with methylene chloride. The dry extract was fractionated and purified by silica gel column chromatography. The isolated compounds were identified by comparison of their Nuclear Magnetic Resonance (NMR) spectral data with those reported in the literature. Antimicrobial activity was assayed by broth macro dilution method. RESULTS: The crude extract of M. angolensis displayed significant antifungal and antibacterial activities (MIC = 312.50-1250mug/ml). 6beta-(2-methylbut-2(Z)-enoyl)-3alpha,4alpha,15,16-bis-epoxy-8beta,10betaH-ent-cleroda-13(16),14-dien-20,12-olide and spinasterol were the most active compounds (MIC = 1.56-100mug/ml) and the most sensitive microorganisms were Enterococcus faecalis and Candida tropicalis for bacteria and yeasts respectively. CONCLUSION: The isolation of these active antibacterial and antifungal principles supports the use of M. angolensis in traditional medicine for the treatment of gastro-intestinal disorders.
[Pubmed: 20336218]
| | 23. |
2010 Feb 4 |
The Creation and Physiological Relevance of Divergent Hydroxylation Patterns in the Flavonoid Pathway
Halbwirth
Int J Mol Sci 2010 Feb 4;11(2):595-621. published online before print
Abstract
Flavonoids and biochemically-related chalcones are important secondary metabolites, which are ubiquitously present in plants and therefore also in human food. They fulfill a broad range of physiological functions in planta and there are numerous reports about their physiological relevance for humans. Flavonoids have in common a basic C6-C3-C6 skeleton structure consisting of two aromatic rings (A and B) and a heterocyclic ring (C) containing one oxygen atom, whereas chalcones, as the intermediates in the formation of flavonoids, have not yet established the heterocyclic C-ring. Flavonoids are grouped into eight different classes, according to the oxidative status of the C-ring. The large number of divergent chalcones and flavonoid structures is from the extensive modification of the basic molecules. The hydroxylation pattern influences physiological properties such as light absorption and antioxidative activity, which is the base for many beneficial health effects of flavonoids. In some cases antiinfective properties are also effected.
[Pubmed: 20386656]
| | 24. |
2007 Jul 03 |
New phenolic esters from the resinous exudate of Haplopappus taeda.
Faini F, Labbé C, Torres R, Rodilla JM, Silva L, Delle Monache F
Fitoterapia. 2007 Dec;78(7-8):611-3. Epub 2007 Jul 03.
Abstract
Two new phenolic esters 9-trans-p-coumaroyloxy-alpha-terpineol (1) and 7-trans-p-coumaroyloxy-taedol (2), both endowed with free radical scavenger activity and cleroda-3,13 (E)-dien-15,18-diol (3) for which a cis stereochemistry at the decalin junction was found, were isolated from the resinous exudate from Haplopappus taeda upper parts.
[Pubmed: 17656041]
| | 25. |
2006 Jun |
Antioxidant screening of medicinal herbal teas.
Speisky H, Rocco C, Carrasco C, Lissi EA, López-Alarcón C
Phytother Res. 2006 Jun;20(6):462-7.
Abstract
Herbal tea consumption is deeply and widely rooted amongst South-American populations. In view of the involvement of oxygen- and nitrogen-reactive species in the ethiogenesis of several diseases, the antioxidant properties of some of the herbal teas most commonly consumed in the southern regions was assessed in vitro. Around one-third of the 13 examined herbs, displayed a substantially higher ability to scavenge ABTS(+.) radicals (TEAC assay), and to quench the pro-oxidant species, hypochlorite (HClO) and peroxynitrite (ONOO(-)). Amongst the tested herbs, teas prepared from Haplopappus baylahuen, Rosa moschata and Peumus boldus showed the highest TEAC and HClO-quenching activities. These herbs were around 5- to 7-fold more potent than the least active herbs. Based on the TEAC assay, 150 mL of tea prepared from H. baylahuen, R. moschata and P. boldus would be equivalent to around 200 mg of Trolox). Teas from H. baylahuen and P. boldus were also found to be particularly potent in quenching HClO. In the ONOO(-) assay, H. baylahuen and Buddleia globosa showed the highest activities. The results obtained suggest that the regular consumption of teas prepared from some of these herbs may be useful potentially to provide the organism with molecules capable of protecting the gastrointestinal tract against certain pathologically relevant oxidant species.
[Pubmed: 16619353]
| | 26. |
2006 May 08 |
Antioxidant activity of coumarins and flavonols from the resinous exudate of Haplopappus multifolius.
Torres R, Faini F, Modak B, Urbina F, Labbé C, Guerrero J
Phytochemistry. 2006 May;67(10):984-7. Epub 2006 May 08.
Abstract
The antioxidant activity of eight coumarins and two flavonols isolated from Haplopappus multifolius was studied with the DPPH radical method. Results show that a high concentration of phenolic coumarins and the presence of quercetin and rhamnetin in the exudates could account for the protection of the plant against oxidative stress. Structures for the coumarins 6-hydroxy-7-[(E,E)-3',7'-dimethyl-2',4',7'-octatrienyloxy] coumarin and 7-[(E)-3'-methyl-4'-hydroxy-2'-butenyloxy] coumarin are proposed on the basis of spectroscopic evidence.
[Pubmed: 16684545]
| | 27. |
2006 Apr 19 |
Characterization of volatile constituents of Haplopappus greenei and studies on the antifungal activity against phytopathogens.
Demirci B, Baser KH, Tabanca N, Wedge DE
J. Agric. Food Chem. 2006 Apr 19;54(8):3146-50.
Abstract
Essential oil of Haplopappus greenei A. Gray was obtained by hydrodistillation of aerial parts, which were subsequently analyzed by gas chromatography and gas chromatography-mass spectrometry. Major components were identified as carvacrol (8.7%), beta-pinene (7.6%), trans-pinocarveol (6.2%), and caryophyllene oxide (5.8%), respectively. In total, 104 components representing 84.9% of the investigated essential oil were characterized. Furthermore, the essential oil was evaluated for antimalarial, antimicrobial, and antifungal activities. However, only antifungal activity was observed against the strawberry anthracnose-causing fungal plant pathogens Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides using the direct overlay bioautography assay. Major essential oil components were also evaluated for antifungal activity; the carvacrol standard demonstrated nonselective activity against the three Colletotrichum species and the other compounds were inactive.
[Pubmed: 16608244]
| | 28. |
2004 Dec 16 |
Antioxidant properties and TLC characterization of four Chilean Haplopappus-species known as bailahuén.
Vogel H, González M, Faini F, Razmilic I, Rodríguez J, Martín JS, Urbina F
J Ethnopharmacol. 2005 Feb 10;97(1):97-100. Epub 2004 Dec 16.
Abstract
"Bailahuén" is the common name of a medicinal shrub native to Chile where this resinous herb is widely used for its liver stimulating properties. Although the official species is Haplopappus baylahuen Remy (Asteraceae), other species of the same genus are also used in different regions as "bailahuén". A thin layer chromatography (TLC) method for rapid identification of different species and detection of adulterations is described for four of the species: Haplopappus baylahuen, Haplopappus taeda Reiche, Haplopappus multifolius Phil., and Haplopappus remyanus Wedd. To confirm efficiency in all species antioxidant properties were screened in resins, infusions, and methanolic extracts by tests of lipid peroxidation in erythrocytes and free radical scavenging activity by DPPH. In both studies Haplopappus baylahuen showed the lowest antioxidant capacity. In DPPH analyses, infusion and resins of Haplopappus baylahuen also showed the lowest and Haplopappus remyanus the major inhibiting activity of free radicals, while Haplopappus multifolius proved to have the highest result when the methanolic extracts were used. The chemical characterization of the studied species showed important levels of flavonoids and coumarins, with flavonoids predominating in Haplopappus taeda, coumarins in Haplopappus multifolius and both of them in Haplopappus baylahuen and Haplopappus remyanus.
[Pubmed: 15652282]
| | 29. |
2004 Jan |
Two new O-geranyl coumarins from the resinous exudate of Haplopappus multifolius.
Torres R, Faini F, Delle Monache F, Delle Monache G
Fitoterapia. 2004 Jan;75(1):5-8.
Abstract
From the resinous exudate of leaves of Haplopappus multifolius two new coumarins were isolated and assigned the structures 6-hydroxy-7-(5'-hydroxy-3',7'-dimethylocta-2',6'-dien)-oxycoumarin (1) and 6-hydroxy-7-(7'-hydroxy-3',7'-dimethylocta-2',5'-dien)-oxy coumarin (2).
[Pubmed: 14693213]
| | 30. |
2003 Jul |
Antibacterial new clerodane diterpenes from the surface of Haplopappus foliosus.
Urzúa A, Torres R, Mendoza L, Delle Monache F
Planta Med. 2003 Jul;69(7):675-7.
Abstract
A biologically monitored fractionation of the resinous exudate extract of Haplopappus foliosus DC. is reported. Purification of the two active fractions yielded 2-alpha-hydroxy- cis-cleroda-3,13(Z),8(17)-trien-15-oic acid (1) and 2-alpha-acetoxy- cis-cleroda-3,13(Z),8(17)-trien-15-oic acid (2), two new clerodane diterpenes.
[Pubmed: 12898428]
| | 31. |
2003 Apr |
Antimycobacterial flavones from Haplopappus sonorensis.
Murillo JI, Encarnación-Dimayuga R, Malmstrøm J, Christophersen C, Franzblau SG
Fitoterapia. 2003 Apr;74(3):226-30.
Abstract
Crude extracts of Haplopappus sonorensis (A. Gray) S.F. Blake (Asteraceae), showed activity against Mycobacterium tuberculosis H(37)Rv. By assay-guided fractionation, 5-hydroxy-3,7,4'-trimethoxyflavone (1). 5,7-dihydroxy-3,4'-dimethoxyflavone (2). and 5,4'-dihydroxy-3,7-dimethoxyflavone (3). were identified as the antimycobacterial principles. Compound 2 was the most active compound.
[Pubmed: 12727485]
| | 32. |
2002 Aug |
Labdane diterpenes from Haplopappus illinitus.
Faini F, Labbé C, Torres R, Delle Monache G, Delle Monache F
Nat Prod Lett. 2002 Aug;16(4):223-8.
Abstract
A chemical study of aerial parts of Haplopappus illinitus afforded five labdane diterpenoids whose structures were elucidated by high field NMR spectroscopy and 2D techniques. Four of them are dicarboxylic acids previously reported as the corresponding dimethyl ester derivatives and the fifth is a new compound.
[Pubmed: 12168755]
| | 33. |
2002 Apr |
New terpenoids from Haplopappus multifolius.
Maatooq GT, Gohar AA, Hoffmann JJ
Pharmazie. 2002 Apr;57(4):282-5.
Abstract
The chemical investigation of the aerial parts of Haplopappus multifolius afforded the new monoterpene 2,9-epoxy-p-menth-6-en-8-ol (7, haplopappol), the new monoterpenoid ester 9-cis-p-coumaroyloxy-alpha-terpineol (8, haplofolin), the new diterpene 18-hydroxylabda-7,13Z-dien-15-oic acid (6) and its known E-isomer (5). In addition, the known dihydroflavones 3',5-dihydroxy-4',7-dimethoxydihydroflavone and 3',4',5-trihydroxy-7-methoxydihydroflavone and the known dihydroflavonols 3',5-dihydroxy-4',7-dimethoxydihydroflavonol and 3',4',5-trihydroxy-3-acetyl-7-methoxydihydroflavonol were also obtained. The structural assignments of these compounds were made possible by the different spectroscopic measurements.
[Pubmed: 11998452]
| | 34. |
2000 Dec |
Diterpenoids from Haplopappus rigidus.
Morales G, Sierra P, Loyola LA, Borquez J
Phytochemistry. 2000 Dec;55(8):863-6.
Abstract
Fractionation of the aerial parts of Haplopappus rigidus Phil., directed by the brine shrimp lethality test (BST), has led to the isolation of two new diterpenoids, rigidusol and deacetylrigidusol. Their structures were established as 13-hydroxy-18-acetoxy-cis-cleroda-3,14-diene (8betaH, 10betaH, 19beta, 20alpha form) and 13,18-dihydroxy-cis-cleroda-3,14-diene (8betaH, 10betaH, 19beta, 20alpha form), respectively. Rigidusol exhibit moderate cytotoxic activity against human breast adenocarcinoma cell line MCF-7. Their structures were established by spectral data, in particular using 2D NMR spectroscopy (DEPT, DQF-COSY, HMQC and HMBC).
[Pubmed: 11140515]
| | 35. |
2000 Nov |
A unique pollen wall mutation in the family Compositae: ultrastructure and genetics.
Jackson RC, Skvarla JJ, Chissoe WF
Am. J. Bot. 2000 Nov;87(11):1571-1577.
Abstract
During a routine screening of pollen fertility in the n = 2 chromosome race of HAPLOPAPPUS: gracilis, a spineless pollen wall mutation was discovered that renders the otherwise functional pollen grains completely unrecognizable as Compositae pollen. Normal HAPLOPAPPUS: pollen is characterized by an outer layer, the ektexine, consisting of large spines supported by a roof (tectum), which in turn is supported by collumellae that are joined basally. A large cavity (cavea) stretches from aperture to aperture and separates columellae bases from the final ektexine unit, the foot layer. The spines, tectum, columellae, and columellae bases are filled with perforations (internal foramina), while the foot layer is without them. Immediately underlying the foot layer is a thickened, lamellate, disrupted, internal foramina-free second exine layer, the endexine. In contrast, the mutant pollen ektexine is a jumble of components with randomly dispersed spines as the only clearly definable unit. The endexine layer is similar to the endexine in normal pollen. The mutation apparently disrupts only the organization of ektexine units, and mutant pollen appears to be without the caveae and foot layer characteristic of normal pollen. In genetic tests, the mutant allele is recessive. There is a simple Mendelian pattern of inheritance of the mutant gene, and its phenotype is under sporophytic control.
[Pubmed: 11080106]
| | 36. |
1998 Jul |
Plant cells in vitro under altered gravity.
Klymchuk DO
J Gravit Physiol. 1998 Jul;5(1):P147-8.
Abstract
Establishing the role of gravity in plant requires information about how gravity regulates the metabolism of individual cells. Plant cells and tissues in vitro are valuable models for such purpose. Disrupted intercellular relations in such models have allowed to elucidate both the gravity role in non-specialised to gravity plant cells and the correlative relation role of an intact plant organism. The data obtained from non-numerous space and clinostat experiments with plant cells in vitro have demonstrated that their metabolism is sensitive to g-environment. The most experiments have shown a decrease in the biomass production and cell proliferation of spaceflight samples compared with ground controls, although there is study reporting of increased biomass production in an anise suspension culture and D. carota crown gall tissue culture. At the same time, results of experiments with single carrot cells and tomato callus culture demonstrated similarities in differentiation process in microgravity and in ground controls. Noted ultrastructural arrangement in cells, especially mitochondria and plastids, have been related to altered energy load and functions of organelles in microgravity, as well as changes in the lipid peroxidation and the content of malonic dyaldehyde in a haplopappus tissue culture under altered gravity supposed with modification of membrane structural-functional state. This article focuses on growth aspects of the cultured cells in microgravity and under clinostat conditions and considers those aspects that require further analysis.
[Pubmed: 11542330]
| | 37. |
1996 Apr |
Enhanced root production in Haplopappus gracilis grown under spaceflight conditions.
Levine HG, Krikorian AD
J Gravit Physiol. 1996 Apr;3(1):17-27.
Abstract
The production and growth of roots in two aseptically maintained clonal populations of Haplopappus gracilis (family Compositae), each with a distinctive pattern of root production, were studied after they had been exposed to space for 5 days aboard a NASA Space Shuttle. Total root production of both populations was 67-95% greater when compared with their Earth-grown controls. Roots were generated: (1) laterally from pre-formed roots, the tips of which had been severed at the time of plantlet insertion into a "horticultural foam" substrate supplied with a nutrient solution; (2) adventitiously from the basal or cut-end portion of shoots; (3) de novo, i.e. from primordial which were non-existent at the outset of the experiment. Roots grew in all directions in space but were uniformly positively gravitropic in ground controls. In space and on Earth, both clonal populations maintained their clone-specific root formation and growth characteristics and produced an equivalent amount of tissue when compared to each other. As on Earth, and as expected, there were fewer and shorter roots on plantlets that formed floral buds. The significance of altered moisture distribution in the "horticultural foam" substrate in space for root growth and the significance of our findings for growing plants in altered gravity environments are discussed.
[Pubmed: 11539304]
| | 38. |
1996 |
Energetic metabolism response in algae and higher plant species from simulation experiments with the clinostat.
Vasilenko A, Popova AF
Adv Space Res. 1996;17(6-7):103-6.
Abstract
Adenylate state is acknowledged to be among the most convenient approaches in the study of physiological changes in plant cells under simulation of altered gravity condition with the clinostat. Adenylate levels and the ATP/ADP ratio in cytoplasmic and mitochondrial extracts of cultivated cells of Haplopappus gracilis and algae cells of Chlorella vulgaris under initial stages of the fast-rotating and slow-rotating clinorotation, as well as the long-term clinorotation, have been investigated. For analysis of ATP and ADP levels in the plant cells under the clinorotation, we applied a high-sensitive bioluminescence method using the luciferase and piruvate kinase enzyme systems. It has been shown that the adenylate ratio is already increased during at the start of clinorotation with the different speed of rotation in the biological material tested. The considerable changes in mitochondrial ultrastructure of Chlorella cells, as well as the rising ATP level and dropping of the ATP/ADP ratio appear after long-duration clinorotation if compared to control material. It is probably connected with the distinctions in ATP-synthetase functioning in mitochondria of the cells under the clinorotation conditions.
[Pubmed: 11538600]
| | 39. |
1995 |
Clinorotation affects soybean seedling morphology.
Hilaire E, Guikema JA, Brown CS
J Gravit Physiol. 1995;2(1):P149-50.
Abstract
Although spaceflight does not appear to significantly affect seed germination, it can influence subsequent plant growth. On STS-3 and SL-2, decreased growth (measured as plant length, fresh weight and dry weight) was noted for pine, oat and mung bean. In the CHROMEX-01 and -02 experiments with Haplopappus and in the CHROMEX-03 experiment with Arabidopsis, enhanced root growth was noted in the space-grown plants. In the CHROMEX-04 experiment with wheat, both leaf fresh weight and leaf area were diminished in the space-grown plants but there was no difference in total plant height (CS Brown, HG Levine, and AD Krikorian, unpublished data). These data suggest that microgravity impacts growth by whole plant partitioning of assimilates. The objective of the present study was to determine the influence of clinorotation on the growth and morphology of soybean seedlings grown in the BRIC (Biological Research In Canister) flight hardware. This experiment provided baseline data for a spaceflight experiment (BRIC-03) flown on STS-63 (Feb. 3-11, 1995).
[Pubmed: 11538905]
| | 40. |
1994 |
Lipid peroxidation of plants under microgravity and its simulation.
Zhadko SI, Polulyakh YuA, Vorobyeva TV, Baraboy VA
Adv Space Res. 1994;14(8):103-6.
Abstract
In series of space experiments aboard the biosatellites "Cosmos 1887", "Bion 9", the orbital stations "Salut", "Mir" and under clinostating, changes of lipid peroxidation (LPO) and antioxidation activity (AOA) of Chlorella, Haplopappus tissue culture, wheat and pea roots were determined. The changes had a complex fluctuation character; three steps of response were established: LPO decreasing accompanied by AOA increase; stabilization LPO <==> AOA balance; secondary LPO activation. Most early and highly amplitude decreasing of LPO were fixed in mitochondria. The rate of response have been increased on multicellular level of plants organization.
[Pubmed: 11537904]
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