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931.
Background
Snake venom toxins evolve more rapidly than other proteins through accelerated changes in the protein coding regions. Previously we have shown that accelerated segment switch in exons to alter targeting (ASSET) might play an important role in its functional evolution of viperid three-finger toxins. In this phenomenon, short sequences in exons are radically changed to unrelated sequences and hence affect the folding and functional properties of the toxins. 相似文献932.
Zhengyuan Wang John Martin Sahar Abubucker Yong Yin Robin B Gasser Makedonka Mitreva 《BMC evolutionary biology》2009,9(1):23
Background
Amino acid insertions and deletions in proteins are considered relatively rare events, and their associations with the evolution and adaptation of organisms are not yet understood. In this study, we undertook a systematic analysis of over 214,000 polypeptides from 32 nematode species and identified insertions and deletions unique to nematode proteins in more than 1000 families and provided indirect evidence that these alterations are linked to the evolution and adaptation of nematodes. 相似文献933.
Background
Island populations are excellent model systems for studies of phenotypic, ecological and molecular evolution. In this study, molecular markers of mitochondrial and nuclear derivation were used to investigate the evolution, structure and origin of populations of the California slender salamander (Batrachoseps attenuatus) inhabiting the six major islands of San Francisco Bay, formed following the rising of sea level around 9,000 years ago. 相似文献934.
935.
Robin L Burke Chris A Whitehouse Justin K Taylor Edward B Selby 《Comparative medicine》2009,59(6):589-597
Invasive Klebsiella pneumoniae with hypermucoviscosity phenotype (HMV K. pneumoniae) is an emerging human pathogen that, over the past 20 y, has resulted in a distinct clinical syndrome characterized by pyogenic liver abscesses sometimes complicated by bacteremia, meningitis, and endophthalmitis. Infections occur predominantly in Taiwan and other Asian countries, but HMV K. pneumoniae is considered an emerging infectious disease in the United States and other Western countries. In 2005, fatal multisystemic disease was attributed to HMV K. pneumoniae in African green monkeys (AGM) at our institution. After identification of a cluster of subclinically infected macaques in March and April 2008, screening of all colony nonhuman primates by oropharyngeal and rectal culture revealed 19 subclinically infected rhesus and cynomolgus macaques. PCR testing for 2 genes associated with HMV K. pneumoniae, rmpA and magA, suggested genetic variability in the samples. Random amplified polymorphic DNA analysis on a subset of clinical isolates confirmed a high degree of genetic diversity between the samples. Environmental testing did not reveal evidence of aerosol or droplet transmission of the organism in housing areas. Further research is needed to characterize HMV K. pneumoniae, particularly with regard to genetic differences among bacterial strains and their relationship to human disease and to the apparent susceptibility of AGM to this organism.Abbreviations: AGM, African green monkey; HMV K. pneumoniae, invasive Klebsiella pneumoniae with hypermucoviscosity phenotype; NHP, nonhuman primate; RAPD, random amplification of polymorphic DNAKlebsiella pneumoniae is an enteric, gram-negative, lactose-fermenting bacillus with a prominent capsule. This bacterium has been associated with peritonitis, septicemia, pneumonia, and meningitis in both Old and New World primates,10,13,29 although it also is reported to constitute normal fecal and oral flora in many nonhuman primates (NHP).12 Pathogenic strains associated with the upper respiratory tract typically are heavily encapsulated.12 Over the past several decades, human medical literature indicates the emergence of an invasive K. pneumoniae disease in Taiwan and other Asian countries, in which community-acquired pyogenic liver abscesses have been attributed to strains of invasive K. pneumoniae with a unique hypermucoviscous phenotype (HMV K. pneumoniae).6,17-19,21,26,34 The hypermucoviscous phenotype has also been associated with other serious complications, including bacteremia, meningitis, and endophthalmitis. This strain of Klebsiella has become an emerging cause of pyogenic liver abscesses in some nonAsian countries, including the United States.16,20,36,39 The majority of clinical cases of HMV K. pneumoniae are in the Asian population, particularly in patients with diabetes mellitus.3,4,33 Determination of the HMV phenotype typically is based on a positive string test.8,35,39Several virulence factors have been associated with HMV K. pneumoniae. Klebsiella spp. generally develop prominent polysaccharide capsules which increase virulence by protecting the bacteria from phagocytosis and preventing destruction by bactericidal serum factors. Capsular serotypes K1 or K2 have been reported as the major virulence determinants for human HMV K. pneumoniae liver abscesses.5,8,37,38 In addition, the mucoviscosity-associated gene magA, which encodes a structural outer membrane protein of the K1 serotype, and rmpA (regulator of the mucoid phenotype gene; located on a plasmid) have been proposed as virulence factors.9,27,31,40,41 Recently, it was suggested that 2 clones, CC23 K1 and CC82K1, are strongly associated with primary liver abscess and respiratory infection, respectively.2Over a period of several months in 2005 to 2006, 7 African green monkeys (AGM; Chlorocebus aethiops) in the US Army Medical Research Institute of Infectious Diseases research colony developed abscesses in multiple locations and either died or were euthanized when the abscesses were determined to be nonresectable.35 HMV K. pneumoniae of the K2 serotype and carrying rmpA was determined to be the cause of the infection in 1 case, and the 6 other cases had similar clinical and pathologic features. This report35 is the only documentation, to our knowledge, of natural infection with HMV K. pneumoniae in NHP. As a result of these cases, the US Army Medical Research Institute of Infectious Diseases instituted policies to exclude HMV K. pneumoniae from the colony. The organism was included as a specific pathogen-free requirement for vendors, and K. pneumoniae culture results were reported during quarantine periods and on routine semiannual examination for all colony NHP. 相似文献
936.
937.
Robin R. Craven Xi Gao Irving C. Allen Denis Gris Juliane Bubeck Wardenburg Erin McElvania-TeKippe Jenny P. Ting Joseph A. Duncan 《PloS one》2009,4(10)
Community Acquired Methicillin Resistant Staphylococcus aureus (CA-MRSA) causes severe necrotizing infections of the skin, soft tissues, and lungs. Staphylococcal α-hemolysin is an essential virulence factor in mouse models of CA-MRSA necrotizing pneumonia. S. aureus α-hemolysin has long been known to induce inflammatory signaling and cell death in host organisms, however the mechanism underlying these signaling events were not well understood. Using highly purified recombinant α-hemolysin, we now demonstrate that α-hemolysin activates the Nucleotide-binding domain and leucine-rich repeat containing gene family, pyrin domain containing 3 protein (NLRP3)-inflammasome, a host inflammatory signaling complex involved in responses to pathogens and endogenous danger signals. Non-cytolytic mutant α-hemolysin molecules fail to elicit NLRP3-inflammasome signaling, demonstrating that the responses are not due to non-specific activation of this innate immune signaling system by bacterially derived proteins. In monocyte-derived cells from humans and mice, inflammasome assembly in response to α-hemolysin results in activation of the cysteine proteinase, caspase-1. We also show that inflammasome activation by α-hemolysin works in conjunction with signaling by other CA-MRSA-derived Pathogen Associated Molecular Patterns (PAMPs) to induce secretion of pro-inflammatory cytokines IL-1β and IL-18. Additionally, α-hemolysin induces cell death in these cells through an NLRP3-dependent program of cellular necrosis, resulting in the release of endogenous pro-inflammatory molecules, like the chromatin-associated protein, High-mobility group box 1 (HMGB1). These studies link the activity of a major S. aureus virulence factor to a specific host signaling pathway. The cellular events linked to inflammasome activity have clear relevance to the disease processes associated with CA-MRSA including tissue necrosis and inflammation. 相似文献
938.
Krishna Jafa Peter McElroy Lisa Fitzpatrick Craig B. Borkowf Robin MacGowan Andrew Margolis Ken Robbins Ae Saekhou Youngpairoj Dale Stratford Alan Greenberg Jennifer Taussig R. Luke Shouse Madeleine LaMarre Eleanor McLellan-Lemal Walid Heneine Patrick S. Sullivan 《PloS one》2009,4(5)
Introduction
HIV prevalence among state prison inmates in the United States is more than five times higher than among nonincarcerated persons, but HIV transmission within U.S. prisons is sparsely documented. We investigated 88 HIV seroconversions reported from 1988–2005 among male Georgia prison inmates.Methods
We analyzed medical and administrative data to describe seroconverters'' HIV testing histories and performed a case-crossover analysis of their risks before and after HIV diagnosis. We sequenced the gag, env, and pol genes of seroconverters'' HIV strains to identify genetically-related HIV transmission clusters and antiretroviral resistance. We combined risk, genetic, and administrative data to describe prison HIV transmission networks.Results
Forty-one (47%) seroconverters were diagnosed with HIV from July 2003–June 2005 when voluntary annual testing was offered. Seroconverters were less likely to report sex (OR [odds ratio] = 0.02, 95% CI [confidence interval]: 0–0.10) and tattooing (OR = 0.03, 95% CI: <0.01–0.20) in prison after their HIV diagnosis than before. Of 67 seroconverters'' specimens tested, 33 (49%) fell into one of 10 genetically-related clusters; of these, 25 (76%) reported sex in prison before their HIV diagnosis. The HIV strains of 8 (61%) of 13 antiretroviral-naïve and 21 (40%) of 52 antiretroviral-treated seroconverters were antiretroviral-resistant.Discussion
Half of all HIV seroconversions were identified when routine voluntary testing was offered, and seroconverters reduced their risks following their diagnosis. Most genetically-related seroconverters reported sex in prison, suggesting HIV transmission through sexual networks. Resistance testing before initiating antiretroviral therapy is important for newly-diagnosed inmates. 相似文献939.
Patty W. Siri‐Tarino Paul T. Williams Harriet S. Fernstrom Robin S. Rawlings Ronald M. Krauss 《Obesity (Silver Spring, Md.)》2009,17(9):1768-1775
Excess adiposity and high‐carbohydrate diets have been associated with an atherogenic lipoprotein phenotype (ALP) characterized by increased concentrations of small, dense low‐density lipoprotein (LDL) particles (pattern B). We tested whether weight loss and normalization of adiposity could reverse ALP in overweight men with pattern B. After consuming a moderate‐carbohydrate, high‐fat diet for 3 weeks, pattern B and nonpattern B (pattern A) men were randomized to a weight loss (n = 60 and n = 36, respectively) or control weight‐stable arm (n = 20 and n = 17, respectively). Men in the weight loss arm consumed ~1,000 fewer calories per day over 9 weeks to induce an average ~9 kg weight loss. In the control group, weight stability was maintained for 4 weeks after randomization. Weight loss led to the conversion of pattern B to pattern A in 58% of baseline pattern B men. Among men who achieved BMIs of <25 kg/m2 (62% of pattern B men vs. 83% of pattern A men), 81% of pattern B men converted to pattern A. Weight loss was associated with a significantly greater decrease in small, dense LDL subclass 3b in pattern B relative to pattern A men. The lipoprotein profiles of pattern A men who converted from pattern B were comparable to those of men with pattern A at baseline. Conversion of LDL subclass pattern B to pattern A and reversal of ALP can be achieved in a high proportion of overweight men by normalization of adiposity. 相似文献
940.
Gordon J. King Kai-En Chen Gautier Robin Jade K. Forwood Bego?a Heras Anil S. Thakur Bostjan Kobe Simon P. Blomberg Jennifer L. Martin 《PloS one》2009,4(11)