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61.
Reovirus-induced apoptosis requires activation of transcription factor NF-kappaB 总被引:5,自引:0,他引:5
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Connolly JL Rodgers SE Clarke P Ballard DW Kerr LD Tyler KL Dermody TS 《Journal of virology》2000,74(7):2981-2989
62.
Julia E. Roberts James W. Watters Jimmy D. Ballard & William F. Dietrich 《Molecular microbiology》1998,29(2):581-591
The lethal factor (LF) toxin that is produced by Bacillus anthracis plays an important role in the pathogenesis of anthrax. LF has mononuclear phagocyte-specific intoxicating effects that are not well understood. We have identified genetic differences in inbred mouse strains that determine whether their cultured macrophages are susceptible to the cytolytic effect of LF intoxication. Our identification of resistant and susceptible mouse strains enabled us to analyse crosses between these strains and to map a single responsible gene (called Ltx1 ) to chromosome 11. Ltx1 probably influences intoxication events that occur after the delivery of LF to the cytosol, as all mouse macrophages are killed by polypeptides containing the catalytic domain of Diphtheria toxin fused to the domain of LF required for cytosolic transport. Furthermore, the susceptibility phenotype is dominant to resistance, suggesting that resistance is caused by an absence of or polymorphism in a molecule that acts jointly with, or downstream of, the activity of LF. Our mapping of Ltx1 is a crucial first step in its positional cloning, which will provide more information about the mechanism of LF intoxication. 相似文献
63.
64.
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
65.
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
66.
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
67.
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
68.
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
69.
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
70.
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