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排序方式: 共有148条查询结果,搜索用时 15 毫秒
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MOLTING PHENOLOGY OF HARBOR SEALS ON TUGIDAK ISLAND, ALASKA 总被引:1,自引:0,他引:1
Raychelle G. Daniel Lauri A. Jemison Grey W. Pendleton Shannon M. Crowley 《Marine Mammal Science》2003,19(1):128-140
We documented the progression and timing of the annual molt of harbor seals on Tugidak Island, Alaska, from 1997 to 1999. In all years the timing of molting differed among age-sex classes. Yearlings molted first, subadults second, adult females third, and lastly adult males. Timing of molting was nearly identical in 1997–1998, whereas in 1999 molting occurred three to six days later for all age-sex classes except yearlings. Estimated dates when peak proportions of each age-sex class were molting ranged from 2 August (yearlings) to 2 September (adult males). The number of seals hauled out was positively related to the proportion of seals in the molt and negatively related to the proportion of seals in the postmolt. Population trend estimates, based on aerial counts conducted during a narrow window within the molting period, are likely biased toward certain age-sex classes. Statistical models used to estimate trend include covariates to help account for within-year variation in seal numbers, but do not account for compositional changes that occur during molting. Population modeling may elucidate the effects of within-year population structure on trend estimates. Monitoring molting phenology at additional sites is necessary to determine the extent of geographic variation in molting. 相似文献
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Kimberly L. Raum-Suryan Michael J. Rehberg Grey W. Pendleton Kenneth W. Pitcher Thomas S. Gelatt 《Marine Mammal Science》2004,20(4):823-850
Population declines of Steller sea lions ( Eumetopias juhatus ) in western Alaska (west of 144°W) may be a result of reduced juvenile survival. We used satellite telemetry to study the at-sea distribution and movement patterns of pup (1.6–11.9 mo) and juvenile (12.0–35.1 mo) Steller sea lions. We studied trip distance, duration, and interhaul-out movements of sea lions in relation to age, sex, and month of year in the decreasing western population (WP; Prince William Sound, Kodiak, Aleutian Islands, Alaska) and the increasing eastern population (EP; Southeast Alaska). We deployed 103 satellite transmitters (29 WP; 74 EP) on sea lions between 1998 and 2001. Round trip distance and duration increased with age, trip distance was greater in the WP than the EP, trip duration was greater for females than males, and haul-out use was clustered. Changes in round trip distance and duration occurred from April to June for all age classes studied indicating that the annual timing of weaning may be less variable than the age of weaning. Overall, 90% of round trips were ≤ 15 km from haul-outs and 84% were <20 h, indicating nearshore areas adjacent to haulouts are critical to the developing juvenile. 相似文献
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Ian R. Pendleton 《Journal of invertebrate pathology》1973,21(1):46-52
Toxin crystals from Bacillus thuringiensis var. entomocidus were lysed by proteases present in gut juice from larval Philosamia ricini (Lepidoptera) with the release of a prototoxin and an activated toxin. Some of the toxic activity of the lysate was complexed with a pheophytinlike pigment and this complex was retarded on filtration through Sephadex gels. A method is described for the removal of the pheophytin from larval protease preparations. The prototoxin has a molecular weight greater than 200,000, determined by its exclusion from Sephadex G-200 and on activation produces a toxin of molecular weight about 50,000. Isoelectric focusing of crystal lysates gave pI values of 4.5 and 6.4 for the prototoxin and toxin, respectively. The antigenic composition of the prototoxin and of the toxin are compared and the significance of antigen h as an indicator of activation is discussed. 相似文献
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Miyajima F Roberts P Swale A Price V Jones M Horan M Beeching N Brazier J Parry C Pendleton N Pirmohamed M 《PloS one》2011,6(8):e22804
Background
Community-associated Clostridium difficile infection (CDI) appears to be an increasing problem. Reported carriage rates by C.difficile are debatable with suggestions that primary asymptomatic carriage is associated with decreased risk of subsequent diarrhoea. However, knowledge of potential reservoirs and intestinal carriage rates in the community, particularly in the elderly, the most susceptible group, is limited. We have determined the presence of C.difficile in the faeces of a healthy elderly cohort living outside of long-term care facilities (LCFs) in the United Kingdom.Methods
Faecal samples from 149 community-based healthy elderly volunteers (median age 81 years) were screened for C.difficile using direct (Brazier''s CCEY) and enrichment (Cooked Meat broth) culture methods and a glutamate dehydrogenase (GDH) immunoassay. Isolates were PCR-ribotyped and analysed for toxin production and the presence of toxin genes.Results
Of 149 faecal samples submitted, six (4%) were found to contain C.difficile. One particular sample was positive by both the GDH immunoassay and direct culture, and concurrently produced two distinct strain types: one toxigenic and the other non-toxigenic. The other five samples were only positive by enrichment culture method. Overall, four C.difficile isolates were non-toxigenic (PCR-ribotypes 009, 026 (n = 2) and 039), while three were toxigenic (PCR-ribotypes 003, 005 and 106). All individuals who had a positive culture were symptom-free and none of them had a history of CDI and/or antibiotics use in the 3 month period preceding recruitment.Conclusions
To our knowledge, this is the first study of the presence of C.difficile in healthy elderly community-dwelling individuals residing outside of LCFs. The observed carriage rate is lower than that reported for individuals in LCFs and interestingly no individual carried the common epidemic strain PCR-ribotype 027 (NAP1/BI). Further follow-up of asymptomatic carriers in the community, is required to evaluate host susceptibility to CDI and identify dynamic changes in the host and microbial environment that are associated with pathogenicity. 相似文献8.
Goodwin BL Pendleton LC Levy MM Solomonson LP Eichler DC 《American journal of physiology. Heart and circulatory physiology》2007,293(2):H1115-H1121
Endothelial dysfunction associated with elevated serum levels of TNF-alpha observed in diabetes, obesity, and congenital heart disease results, in part, from the impaired production of endothelial nitric oxide (NO). Cellular NO production depends absolutely on the availability of arginine, substrate of endothelial nitric oxide synthase (eNOS). In this report, evidence is provided demonstrating that treatment with TNF-alpha (10 ng/ml) suppresses not only eNOS expression but also the availability of arginine via the coordinate suppression of argininosuccinate synthase (AS) expression in aortic endothelial cells. Western blot and real-time RT-PCR demonstrated a significant and dose-dependent reduction of AS protein and mRNA when treated with TNF-alpha with a corresponding decrease in NO production. Reporter gene analysis demonstrated that TNF-alpha suppresses the AS proximal promoter, and EMSA analysis showed reduced binding to three essential Sp1 elements. Inhibitor studies suggested that the repression of AS expression by TNF-alpha may be mediated, in part, via the NF-kappaB signaling pathway. These findings demonstrate that TNF-alpha coordinately downregulates eNOS and AS expression, resulting in a severely impaired citrulline-NO cycle. The downregulation of AS by TNF-alpha is an added insult to endothelial function because of its important role in NO production and in endothelial viability. 相似文献
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Kate L Holliday Wendy Thomson Tuhina Neogi David T Felson Ke Wang Frederick C Wu Ilpo T Huhtaniemi Gyorgy Bartfai Felipe Casanueva Gianni Forti Krzysztof Kula Margus Punab Dirk Vanderschueren Gary J Macfarlane Michael A Horan William Ollier Antony Payton Neil Pendleton John McBeth 《Molecular pain》2012,8(1):1-5