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71.
T. Eric Ballard Xia Wang Igor Olekhnovich Taylor Koerner Craig Seymour Paul S. Hoffman Timothy L. Macdonald 《Bioorganic & medicinal chemistry letters》2010,20(12):3537-3539
Head group analogues of the antibacterial and antiparasitic drug nitazoxanide (NTZ) are presented. A library of 39 analogues was synthesized and assayed for their ability to suppress growth of Helicobacter pylori, Campylobacter jejuni, Clostridium difficile and inhibit NTZ target pyruvate:ferredoxin oxidoreductase (PFOR). Two head groups assayed recapitulated NTZ activity and possessed improved activity over their 2-amino-5-nitrothiazole counterparts, demonstrating that head group modification is a viable route for the synthesis of NTZ-related antibacterial analogues. 相似文献
72.
A. A. Echelle J. C. Hackler J. B. Lack S. R. Ballard J. Roman S. F. Fox D. M. LeslieJr. R. A. Van Den Bussche 《Conservation Genetics》2010,11(4):1375-1387
A previous mtDNA study indicated that female-mediated gene flow was extremely rare among alligator snapping turtle populations
in different drainages of the Gulf of Mexico. In this study, we used variation at seven microsatellite DNA loci to assess
the possibility of male-mediated gene flow, we augmented the mtDNA survey with additional sampling of the large Mississippi
River System, and we evaluated the hypothesis that the consistently low within-population mtDNA diversity reflects past population
bottlenecks. The results show that dispersal between drainages of the Gulf of Mexico is rare (F
STmsat
= 0.43, ΦSTmtDNA = 0.98). Past range-wide bottlenecks are indicated by several genetic signals, including low diversity for microsatellites
(1.1–3.9 alleles/locus; H
e = 0.06–0.53) and mtDNA (h = 0.00 for most drainages; π = 0.000–0.001). Microsatellite data reinforce the conclusion from mtDNA that the Suwannee River population might eventually
be recognized as a distinct taxonomic unit. It was the only population showing fixation or near fixation for otherwise rare
microsatellite alleles. Six evolutionarily significant units are recommended on the basis of reciprocal mtDNA monophyly and
high levels of microsatellite DNA divergence. 相似文献
73.
Shawn P. Haskell Warren B. Ballard Mark C. Wallace Mary H. Humphrey David A. Butler 《The Journal of wildlife management》2010,74(8):1686-1692
ABSTRACT Postpartum behavior of maternal deer may be specific to species of deer and predators. We captured sympatric white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus eremicus) fawns from radiocollared adult females in 2004–2006 on rangelands of west central Texas, USA, where predators larger than bobcats (Lynx rufus) were absent. Our objective was to determine whether differences in postpartum antipredator behavior existed between deer species, and if so, examine efficacy of those strategies. We collected postpartum group cohesion data in 2004 and 2005 by using radiotelemetry and examined dead fawns for cause of mortality. During fawns' hider phase, <3 weeks postpartum, mule deer females kept fawns closer to themselves (95% CI = 39−66 m) and twins closer to each other (95% CI = 25–49 m) than did white-tailed deer females (95% CIs = 152–234 m and 163–255 m, respectively). After 30 days postpartum, familial group cohesion was similarly tight for both species. During hider phases from 2004 to 2006, predated carcasses of white-tailed deer fawns (11 of 11) were dismembered or consumed more than mule deer fawns (7 of 13, P = 0.016), which was one line of evidence for maternal defense by mule deer adults. During hider phases in 2004 and 2005, predation rate of mule deer fawns was lower than that for white-tailed deer fawns. In 2006, predation rate increased for mule deer but was similar for white-tailed deer fawns compared with previous years. The tight cohesion strategy of mule deer exhibited in 2004 and 2005 seemed successful at thwarting small predators. Without large predators, the loose cohesion strategy of white-tailed deer females was maladaptive. When meso-predators are abundant due to extermination of larger predators, predation on fawns could increase if a deer species has relatively fixed postpartum maternal antipredator behavior. 相似文献
74.
Plant genotypes of Trifolium subterraneum L. (subterranean clover) were evaluated for differences in symbiotic N2 fixation with soil rhizobia, with the long-term aim of using plant selection to overcome sub-optimal N2 fixation associated with poorly effective soil rhizobia. Symbiotic performance (SP) was assessed for 49 genotypes of subterranean clover with each of four pure Rhizobium strains isolated from soil. Plants were grown in N free media in the greenhouse and their shoot dry weights measured and expressed as a percentage of dry weight with R. leguminosarm bv. trifolii WSM1325, the recommended commercial inoculant. Average SP with two Rhizobium strains (H and J) ranged from completely ineffective to 80% of potential for the subterranean clover genotypes. Two clover cultivars with high (cv. Campeda) and low (cv. Clare) SP values were investigated in more detail. Campeda typically fixed more N2 than Clare when inoculated with 30 soil extracts (4.2 vs 2.4 mg N2 fixed/shoot) and with 14 pure strains isolated from those soils (4.2 vs 2.2 mg N2 fixed/shoot). The poor performance of Clare could be attributed to interruptions at multiple stages of the symbiotic association, from nodule initiation (less nodules), nodule development (small, white nodules), through to reduced nodule function (N2 fixed/mg nodule) depending on the inoculation treatment. Through the careful use of subterranean clover genotypes by plant breeders it should be possible to make significant gains in the SP of future subterranean clover cultivars. 相似文献
75.
The primary causes of age-related changes in mitochondrial metabolism are not known. The goal of this study is to document the influence of naturally occurring mtDNA variation on age dependent changes in mitochondrial respiration, hydrogen peroxide (H(2)O(2)) generation and antioxidant defenses in the fly Drosophila simulans. Possible changes include an increase in rates of reactive oxygen species production with age and/or an age dependent decrease in antioxidant response. For this study we have used flies harboring distinct siII and siIII mtDNA types. Previously we have shown that males harboring siII mtDNA had higher rates of mitochondrial H(2)O(2) production from complex III at 11d compared to males with the siIII mtDNA type. Here, we corroborate those results and show that Drosophila harboring the siII and siIII mtDNA types exhibit significantly different patterns of pro-oxidant and antioxidant activities as they age. Flies harboring siII mtDNA had higher rates of mitochondrial H(2)O(2) production and manganese superoxide dismutase activity at 11 and 18d of age than siIII mtDNA harboring flies. Copper-zinc superoxide dismutase activity increased from 11 to 25d in siII flies while the accumulation of oxidized glutathione did not change between 11 and 25d. In contrast, siIII harboring flies showed an age dependent increase in H(2)O(2) production, reaching higher production rates on day 25 than that observed in siII flies. Copper-zinc superoxide dismutase activities did not change between 11 and 25d while the oxidized glutathione accumulation increased with age. The results show antioxidant levels correlate with pro-oxidant levels in siII but not siIII flies. These results demonstrate our ability to correlate mtDNA variation with differences in whole mitochondrial physiology and individual complex biochemistry. 相似文献
76.
The role of mitochondrial DNA (mtDNA) in mitochondrial metabolism is understudied yet humans harboring specific mtDNA types age at dissimilar rates, are unequally susceptible to various diseases, and differentially adapt to various environmental conditions. This study compares mitochondrial respiration, proton leak and electron transport of Drosophila simulans males with distinct mtDNA haplogroups (siII and -III) that were collected in sympatry in Kenya. Despite the large divergence among haplogroups there is very low intrahaplogroup variation and no correlated variation in the nuclear genome has been detected. We show that repeatable bioenergetic differences exist between 11d old males harboring siII and siIII mtDNA. Males with siIII mtDNA showed higher (i) state 3 respiration rates from isolated mitochondria for both complex I and complex III based substrates, and (ii) complex IV (cytochrome c oxidase) activity. Males harboring siIII mtDNA had lower (i) hydrogen peroxide formation by both complexes I and III, (ii) proton leak from isolated mitochondria, (iii) mitochondrial ATPase activity, and (iv) mitochondrial cytochrome content. In combination, the results suggest that mitochondria isolated from siIII mtDNA harboring males have more efficient metabolism than siII mtDNA harboring males. 相似文献
77.
Zhang Y Eric Ballard C Zheng SL Gao X Ko KC Yang H Brandt G Lou X Tai PC Lu CD Wang B 《Bioorganic & medicinal chemistry letters》2007,17(3):707-711
Maintaining a proper balance of metal concentrations is critical to the survival of bacteria. We have designed and synthesized a series of conjugates of metal chelators and efflux transporter substrates aimed at disrupting bacterial metal homeostasis to achieve bacterial killing. Biological studies showed that two of the compounds had very significant antimicrobial effect with an MIC value of 7.8 microg/mL against Gram-positive Bacillus subtilis. 相似文献
78.
Testing assumptions of central place foraging theory: a study of Adélie penguins Pygoscelis adeliae in the Ross Sea
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R. Glenn Ford David G. Ainley Amelie Lescroël Phil O'B. Lyver Viola Toniolo Grant Ballard 《Journal of avian biology》2015,46(2):193-205
We investigated central place foraging (CPF) in the context of optimal foraging theory in Adélie penguins Pygoscelis adeliae of the southern Ross Sea by using satellite tracking and time‐depth recorders to explore foraging at two spatio‐temporal scales: within the day‐to‐day (sub‐mesoscale: single foraging trip, 10s of km2) and the entire breeding season (mesoscale: trips by multiple individuals across the collective foraging area, 100s of km2). Specifically, we examine whether three basic assumptions of the Orians–Pearson CPF model, shown to occur in other CPF species, are met: 1) within a patch, the rate of prey acquisition declines with time spent in that patch; 2) food is distributed in discrete patches and is not available between those patches; and 3) CPF species have knowledge of the potential (or average, at least) feeding rate within their universe of patches, and use this knowledge to determine their foraging strategy when planning or engaging in a foraging trip. We found that prey consumption rates did not decline with time spent in patches, and penguins foraged to some degree most of the time when at sea. Food availability, as measured by foraging dive rate, appeared to be predictable within the same day at the same location, but predictability broke down after 2 d at distances > 10 km away. We conclude that the assumptions of the Orians–Pearson CPF model are not a good fit to the circumstances of Ross Sea penguins, which clearly are central place foragers. 相似文献
79.
目的筛选与Rap GAP相互作用的蛋白质,为进一步研究人源Rap1GAP介导的信号转导通路、揭示其与肿瘤的关系提供实验依据。方法选用与Rap1GAP同源的来自美丽线虫的Rap GAP作为饵蛋白,以来源于美丽线虫的c DNA文库作为靶蛋白,应用p PC97、p PC86组成的酵母双杂交系统筛选c DNA文库中与Rap GAP相互作用的蛋白质。结果通过营养缺陷平板(-LTH)筛选出63个拟似阳性菌落。经过Lac Z鉴定,19个菌落为阳性,其中7个为强阳性。提取来自19个酵母菌落中的重组DNA,经PCR扩增,12个菌落出现阳性结果。将该19个重组DNA分别电转化入DH5α细菌,涂板培养后,每板挑取4~10个克隆,通过Sal I和Not I双酶切鉴定进行阳性克隆筛选。将阳性克隆的重组DNA进行序列测定。测序结果与Gen Bank比较,其中4个克隆的DNA片段为Y39b6a基因片段、2个为Rap GAP、1个为苯丙氨酸-4-羟化酶、1个为细胞色素C氧化酶,还有1个DNA片段编码美丽线虫特有的小分子蛋白的基因片段,其余11个DNA片段不编码已知蛋白质。结论初步筛选出与Rap GAP相互作用的蛋白质,特别是其中有2个克隆为Rap GAP,提示Rap GAP可能以二聚体的方式存在。 相似文献
80.
Thomas D Niehaus Svetlana Gerdes Kelsey Hodge-Hanson Aleksey Zhukov Arthur JL Cooper Mona ElBadawi-Sidhu Oliver Fiehn Diana M Downs Andrew D Hanson 《BMC genomics》2015,16(1)