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991.
992.
Muhammad Arshad Javier Gonzalez Abdel Aziz El-Sayed Tim Osborne Michael Wink 《Journal of Ornithology》2009,150(2):419-430
Populations of Oriental White-backed Vulture (Gyps bengalensis) and Long-billed Vulture (Gyps indicus) dramatically declined by 95–100% on the Indian subcontinent in mid-1990s. The present study was conducted to discover the
phylogeny and phylogeography of Gyps species based on nuclear (recombination activating gene, RAG-1) and mitochondrial (cytochrome b, cytb) markers. Gyps species showed monophyly and no geographic partition was observed within the three groups of Gyps species (G. bengalensis, G. indicus and G. fulvus) despite the large sample size available (n = 149). Our study supports the treatment of G. indicus and G.
tenuirostris as separate species. In all analyses, the earliest divergence separated G. bengalensis from all other Gyps taxa while a sister relationship was supported between G. fulvus and G. rueppellii, and these two taxa together were sister group to a clade consisting of G. indicus, G. tenuirostris and G. coprotheres. Molecular clock estimates of both nuclear and mitochondrial (RAG-1, cytb) genes indicated a rapid and recent diversification within the Gyps species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
993.
记河北省后城组新发现之小型兽脚类足迹(英文) 总被引:2,自引:0,他引:2
几十年前人们就已经开始研究中国东北侏罗纪—白垩纪界线附近地层中的小型兽脚类恐龙足迹,虽然这些遗迹化石比辽宁省义县组带羽毛的恐龙及其他实体化石逊色了许多。本文记述了河北省承德南双庙后城组(土城子组)最下部河流相沉积中发现的一组兽脚类恐龙足迹。南双庙足迹具有三趾,趾粗大,其形态与美国下侏罗统经典的"brontozoid"足迹(Gral- lator,Anchisauripus和Eubrontes)相符。虽然许多产自辽宁土城子组中基本同时的brontozoid足迹被鉴定为小型的跷脚龙足迹属(Grallator),但南双庙足迹更大一些(全长可达28.8 cm),可能应该归入安琪龙足迹属(Anchisauripus)。南双庙足迹很可能是一群小型兽脚类行走而产生。在辽宁义县组的兽脚类恐龙中,最可能留下这类足迹的是小型的窃蛋龙类——尾羽龙(Caudipteryx)。不过这个解释还很勉强,因为这些足迹缺乏鉴定性特征,而且河北的后城组与辽宁的义县组之间还有一定的时间及地理间隔。 相似文献
994.
Patrick Hauske Michael Meltzer Christian Ottmann Tobias Krojer Tim Clausen Michael Ehrmann Markus Kaiser 《Bioorganic & medicinal chemistry》2009,17(7):2920-2924
Protein quality control factors are involved in many key physiological processes and severe human diseases that are based on misfolding or amyloid formation. Prokaryotic representatives are often virulence factors of pathogenic bacteria. Therefore, protein quality control factors represent a novel class of drug targets. The bacterial serine protease DegP, belonging to the widely conserved family of HtrA proteases, exhibits unusual structural and functional plasticity that could be exploited by small molecule modulators. However, only one weak synthetic peptide substrate and no inhibitors are available to date. We report the identification of a potent heptameric pNA-substrate and chloromethyl ketone based inhibitors of DegP. In addition, specificity profiling resulted in the identification of one strong inhibitor and a potent substrate for subtilisin as well as a number of specific elastase substrates and inhibitors. 相似文献
995.
996.
Somites are the mesodermal segments of vertebrate embryos that become the vertebral column, skeletal muscle and dermis. Somites arise within the paraxial mesoderm by the periodic, bilaterally symmetric process of somitogenesis. However, specification of left–right asymmetry occurs in close spatial and temporal proximity to somitogenesis and involves some of the same cell signaling pathways that govern segmentation. Here, we review recent evidence that identifies cross-talk between these processes and that demonstrates a role for retinoic acid in maintaining symmetrical somitogenesis by preventing impingement of left–right patterning signals upon the paraxial mesoderm. 相似文献
997.
Potential To Reduce Escherichia coli Shedding in Cattle Feces by Using Sainfoin (Onobrychis viciifolia) Forage, Tested In Vitro and In Vivo
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Natalie C. Berard Richard A. Holley Tim A. McAllister Kim H. Ominski Karin M. Wittenberg Kristen S. Bouchard Jenelle J. Bouchard Denis O. Krause 《Applied microbiology》2009,75(4):1074-1079
There is a growing concern about the presence of pathogens in cattle manure and its implications on human and environmental health. The phytochemical-rich forage sainfoin (Onobrychis viciifolia) and purified phenolics (trans-cinnamic acid, p-coumaric acid, and ferulic acid) were evaluated for their ability to reduce the viability of pathogenic Escherichia coli strains, including E. coli O157:H7. MICs were determined using purified phenolics and acetone extracts of sainfoin and alfalfa (Medicago sativa), a non-tannin-containing legume. Ground sainfoin or pure phenolics were mixed with fresh cattle feces and inoculated with a ciprofloxacin-resistant strain of E. coli, O157:H7, to assess its viability at −20°C, 5°C, or 37°C over 14 days. Forty steers were fed either a sainfoin (hay or silage) or alfalfa (hay or silage) diet over a 9-week period. In the in vitro study, the MICs for coumaric (1.2 mg/ml) and cinnamic (1.4 mg/ml) acids were 10- to 20-fold lower than the MICs for sainfoin and alfalfa extracts. In the inoculated feces, the −20°C treatment had death rates which were at least twice as high as those of the 5°C treatment, irrespective of the additive used. Sainfoin was less effective than coumaric acid in reducing E. coli O157:H7 Cipr in the inoculated feces. During the animal trial, fecal E. coli numbers declined marginally in the presence of sainfoin (silage and hay) and alfalfa silage but not in the presence of hay, indicating the presence of other phenolics in alfalfa. In conclusion, phenolic-containing forages can be used as a means of minimally reducing E. coli shedding in cattle without affecting animal production. 相似文献
998.
999.
Brian S. Baltunis Harry X. Wu Heidi S. Dungey T. J. “Tim” Mullin Jeremy T. Brawner 《Tree Genetics & Genomes》2009,5(1):269-278
Different methods for predicting clonal values were explored for diameter growth (diameter at breast height (DBH)) in a radiata
pine clonal forestry program: (1) clones were analyzed with a full model in which the total genetic variation was partitioned
into additive, dominance, and epistasis (Clone Only—Full Model); (2) clones were analyzed together with seedling base population
data (Clone Plus Seedling (CPS)), and (3) clones were analyzed with a reduced model in which the only genetic term was the
total genetic variance (Clone Only—Reduced Model). DBH was assessed at age 5 for clones and between ages 4 to 13 at the seedling
trials. Significant additive, dominance, and epistatic genetic effects were estimated for DBH using the CPS model. Nonadditive
genetic effects for DBH were 87% as large as additive genetic effects. Narrow-sense () and broad-sense () heritability estimates for DBH using the CPS model were 0.14 ± 0.01 and 0.26 ± 0.01, respectively. Accuracy of predicted
clonal values increased 4% by combining the clone and seedling data over using clonal data alone, resulting in greater confidence
in the predicted genetic performance of clones. Our results indicate that exploiting nonadditive genetic effects in clonal
varieties will generate greater gains than that typically obtainable from conventional family-based forestry of radiata pine.
The predicted genetic gain for DBH from deployment of the top 5% of clones was 24.0%—an improvement of more than 100% over
family forestry at the same selection intensity. We conclude that it is best practice to predict clonal values by incorporating
seedling base population data in the clonal analysis. 相似文献
1000.
Thomas Cornulier David A. Elston Peter Arcese Tim G. Benton David J.T. Douglas Xavier Lambin Jane Reid Robert A. Robinson William J. Sutherland 《Ecology letters》2009,12(11):1184-1193
Well-established statistical methods exist to estimate variation in a number of key demographic rates from field data, including life-history transition probabilities and reproductive success per attempt. However, our understanding of the processes underlying population change remains incomplete without knowing the number of reproductive attempts individuals make annually; this is a key demographic rate for which we have no satisfactory method of estimating. Using census data to estimate this parameter from requires disaggregating the overlying temporal distributions of first and subsequent breeding attempts. We describe a Bayesian mixture method to estimate the annual number of reproductive attempts from field data to provide a new tool for demographic inference. We validate our method using comprehensive data on individually-marked song sparrows Melospiza melodia , and then apply it to more typical nest record data collected over 45 years on yellowhammers Emberiza citrinella . We illustrate the utility of our method by testing, and rejecting, the hypothesis that declines in UK yellowhammer populations have occurred concurrently with declines in annual breeding frequency. 相似文献