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111.
Masaki Sano M.S. Sheshshayee S. Managave R. Ramesh R. Sukumar Tatsuo Sweda 《Dendrochronologia》2010,28(2):93-98
A 50-year tree-ring δ18O chronology of Abies spectabilis growing close to the tree line (3850 m asl) in the Nepal Himalaya is established to explore its dendroclimatic potential. Response function analysis with ambient climatic records revealed that tree-ring δ18O is primarily governed by rainfall during the monsoon season (June–September), and the regression model accounts for 35% of the variance in rainfall. Extreme dry years identified in instrumental weather data are detected in the δ18O chronology. Further, tree-ring δ18O is much more sensitive to rainfall fluctuations than other tree-ring parameters such as width and density typically used in dendroclimatology. Correlation analyses with Niño 3.4 SST reveal time-dependent behavior of ENSO–monsoon relationships. 相似文献
112.
Tree diameter growth is sensitive to environmental fluctuations and tropical dry forests experience high seasonal and inter-annual
environmental variation. Tree growth rates in a large permanent plot at Mudumalai, southern India, were examined for the influences
of rainfall and three intrinsic factors (size, species and growth form) during three 4-year intervals over the period 1988–2000.
Most trees had lowest growth during the second interval when rainfall was lowest, and skewness and kurtosis of growth distributions
were reduced during this interval. Tree diameter generally explained <10% of growth variation and had less influence on growth
than species identity or time interval. Intraspecific variation was high, yet species identity accounted for up to 16% of
growth variation in the community. There were no consistent differences between canopy and understory tree growth rates; however,
a few subgroups of species may potentially represent canopy and understory growth guilds. Environmentally-induced temporal
variations in growth generally did not reduce the odds of subsequent survival.
Growth rates appear to be strongly influenced by species identity and environmental variability in the Mudumalai dry forest.
Understanding and predicting vegetation dynamics in the dry tropics thus also requires information on temporal variability
in local climate. 相似文献
113.
114.
Antuch W Menon S Chen QZ Lu Y Sakamuri S Beck B Schauer-Vukasinović V Agarwal S Hess S Dömling A 《Bioorganic & medicinal chemistry letters》2006,16(6):1740-1743
A terphenyl alpha-helix mimetic scaffold recognized to be capable of disrupting protein-protein interactions was structurally morphed into an easily amenable and versatile multicomponent reaction (MCR) backbone. The design, modular in-parallel library synthesis, initial cell based biological data, and preliminary in vitro screening for the disruption of the Bcl-w/Bak protein-protein interaction by representatives of the MCR derived scaffold are presented. 相似文献
115.
116.
Tak Fung Ryan A. Chisholm Kristina Anderson‐Teixeira Norm Bourg Warren Y. Brockelman Sarayudh Bunyavejchewin Chia‐Hao Chang‐Yang Rutuja Chitra‐Tarak George Chuyong Richard Condit Handanakere S. Dattaraja Stuart J. Davies Corneille E. N. Ewango Gary Fewless Christine Fletcher C. V. Savitri Gunatilleke I. A. U. Nimal Gunatilleke Zhanqing Hao J. Aaron Hogan Robert Howe Chang‐Fu Hsieh David Kenfack YiChing Lin Keping Ma Jean‐Remy Makana Sean McMahon William J. McShea Xiangcheng Mi Anuttara Nathalang Perry S. Ong Geoffrey Parker E‐Ping Rau Jessica Shue Sheng‐Hsin Su Raman Sukumar I‐Fang Sun Hebbalalu S. Suresh Sylvester Tan Duncan Thomas Jill Thompson Renato Valencia Martha I. Vallejo Xugao Wang Yunquan Wang Pushpa Wijekoon Amy Wolf Sandra Yap Jess Zimmerman 《Ecology letters》2020,23(1):160-171
Among the local processes that determine species diversity in ecological communities, fluctuation‐dependent mechanisms that are mediated by temporal variability in the abundances of species populations have received significant attention. Higher temporal variability in the abundances of species populations can increase the strength of temporal niche partitioning but can also increase the risk of species extinctions, such that the net effect on species coexistence is not clear. We quantified this temporal population variability for tree species in 21 large forest plots and found much greater variability for higher latitude plots with fewer tree species. A fitted mechanistic model showed that among the forest plots, the net effect of temporal population variability on tree species coexistence was usually negative, but sometimes positive or negligible. Therefore, our results suggest that temporal variability in the abundances of species populations has no clear negative or positive contribution to the latitudinal gradient in tree species richness. 相似文献
117.
The occurrence of musth, a period of elevated levels of androgens and heightened sexual activity, has been well documented for the male Asian elephant (Elephas maximus). However, the relationship between androgen-dependent musth and adrenocortical function in this species is unclear. The current study is the first assessment of testicular and adrenocortical function in free-ranging male Asian elephants by measuring levels of testosterone (androgen) and cortisol (glucocorticoid – a physiological indicator of stress) metabolites in faeces. During musth, males expectedly showed significant elevation in faecal testosterone metabolite levels. Interestingly, glucocorticoid metabolite concentrations remained unchanged between musth and non-musth periods. This observation is contrary to that observed with wild and captive African elephant bulls and captive Asian bull elephants. Our results show that musth may not necessarily represent a stressful condition in free-ranging male Asian elephants. 相似文献
118.
Rotaviruses (RV) are a major cause of gastroenteritis in children. Widespread vitamin A deficiency is associated with reduced efficacy of vaccines and higher incidence of diarrheal infections in children in developing countries. We established a vitamin A deficient (VAD) gnotobiotic piglet model that mimics subclinical vitamin A deficiency in children to study its effects on an oral human rotavirus (HRV) vaccine and virulent HRV challenge. Piglets derived from VAD and vitamin A sufficient (VAS) sows were orally vaccinated with attenuated HRV or mock, with/without supplemental vitamin A and challenged with virulent HRV. Unvaccinated VAD control piglets had significantly lower hepatic vitamin A, higher severity and duration of diarrhea and HRV fecal shedding post-challenge as compared to VAS control pigs. Reduced protection coincided with significantly higher innate (IFNα) cytokine and CD8 T cell frequencies in the blood and intestinal tissues, higher pro-inflammatory (IL12) and 2-3 fold lower anti-inflammatory (IL10) cytokines, in VAD compared to VAS control pigs. Vaccinated VAD pigs had higher diarrhea severity scores compared to vaccinated VAS pigs, which coincided with lower serum IgA HRV antibody titers and significantly lower intestinal IgA antibody secreting cells post-challenge in the former groups suggesting lower anamnestic responses. A trend for higher serum HRV IgG antibodies was observed in VAD vs VAS vaccinated groups post-challenge. The vaccinated VAD (non-vitamin A supplemented) pigs had significantly higher serum IL12 (PID2) and IFNγ (PID6) compared to vaccinated VAS groups suggesting higher Th1 responses in VAD conditions. Furthermore, regulatory T-cell responses were compromised in VAD pigs. Supplemental vitamin A in VAD pigs did not fully restore the dysregulated immune responses to AttHRV vaccine or moderate virulent HRV diarrhea. Our findings suggest that that VAD in children in developing countries may partially contribute to more severe rotavirus infection and lower HRV vaccine efficacy. 相似文献
119.
Sukumar Chakraborty 《Global Change Biology》2013,19(7):1985-2000
Findings on climate change influence on plant pathogens are often inconsistent and context dependent. Knowledge of pathogens affecting agricultural crops and natural plant communities remains fragmented along disciplinary lines. By broadening the perspective beyond agriculture, this review integrates cross‐disciplinary knowledge to show that at scales relevant to climate change, accelerated evolution and changing geographic distribution will be the main implications for pathogens. New races may evolve rapidly under elevated temperature and CO2, as evolutionary forces act on massive pathogen populations boosted by a combination of increased fecundity and infection cycles under favourable microclimate within enlarged canopy. Changing geographic distribution will bring together diverse lineages/genotypes that do not share common ecological niche, potentially increasing pathogen diversity. However, the uncertainty of model predictions and a lack of synthesis of fragmented knowledge remain as major deficiencies in knowledge. The review contends that the failure to consider scale and human intervention through new technology are major sources of uncertainty. Recognizing that improved biophysical models alone will not reduce uncertainty, it proposes a generic framework to increase focus and outlines ways to integrate biophysical elements and technology change with human intervention scenarios to minimize uncertainty. To synthesize knowledge of pathogen biology and life history, the review borrows the concept of ‘fitness’ from population biology as a comprehensive measure of pathogen strengths and vulnerabilities, and explores the implications of pathogen mode of nutrition to fitness and its interactions with plants suffering chronic abiotic stress under climate change. Current and future disease management options can then be judged for their ability to impair pathogenic and saprophytic fitness. The review pinpoints improving confidence in model prediction by minimizing uncertainty, developing management strategies to reduce overall pathogen fitness, and finding new sources of data to trawl for climate signatures on pathogens as important challenges for future research. 相似文献
120.
Sule SV Sukumar M Weiss WF Marcelino-Cruz AM Sample T Tessier PM 《Biophysical journal》2011,(7):1749-1757
Monoclonal antibodies are typically monomeric and nonviscous at low concentrations, yet they display highly variable associative and viscous behavior at elevated concentrations. Although measurements of antibody self-association are critical for understanding this complex behavior, traditional biophysical methods are not capable of characterizing such concentration-dependent self-association in a high-throughput manner. Here we describe a nanoparticle-based method, termed self-interaction nanoparticle spectroscopy, that is capable of rapidly measuring concentration-dependent self-interactions for three human monoclonal antibodies with unique solution behaviors. We demonstrate that gold nanoparticles conjugated with antibodies at low protein concentrations (<40 μg/mL) display self-association behavior (as measured by the interparticle distance-dependent plasmon wavelength) that is well correlated with static light-scattering measurements obtained at three orders of magnitude higher antibody concentrations. Using this methodology, we find that the antibodies display a complex pH-dependent self-association behavior that is strongly influenced by the solution ionic strength. Importantly, we find that a polyclonal human antibody is nonassociative for all solution conditions evaluated in this work, suggesting that antibody self-association is more specific than previously realized. We expect that our findings will guide rational manipulation of antibody phase behavior, and enable studies that elucidate sequence and structural determinants of antibody self-association. 相似文献