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Elizabeth Throckmorton Travis Brenden Amber K. Peters Tammy J. Newcomb Gary E. Whelan Mohamed Faisal 《Journal of aquatic animal health》2013,25(1):31-42
AbstractViral hemorrhagic septicemia virus genotype IVb (VHSV IVb) has caused major, sporadic fish die-offs in the Laurentian Great Lakes region of North America since 2005. Presently, factors affecting VHSV IVb persistence in enzootic systems are not well understood. Even with annual surveillance, the virus can go undetected for several years after an outbreak before again re-emerging, which suggests that the virus is maintained in the system either below detectable levels or in untested reservoirs. The aim of this study was to identify potential reservoirs of VHSV IVb in Budd Lake, Michigan; VHSV IVb was first detected in Budd Lake in 2007 but remained undetected until 2011. Additionally, we explored the susceptibility of naive fish introduced into a water body enzootic for VHSV IVb by stocking age-0 Largemouth Bass Micropterus salmoides at varying densities into enclosures in the lake. The virus was not detected among samples of the fishes Notropis spp. and Lepomis spp., cylindrical papershell mussels Anodontoides ferussacianus, leeches (subclass Hirudinea), sediment, or water. However, the virus was successfully isolated from amphipods (family Hyalellidae) and Largemouth Bass held in the enclosures. Our finding of VHSV IVb in Hyalellidae amphipods in combination with other research that has detected the virus in Diporeia spp., a large benthic amphipod important as a food resource to Great Lake fishes, suggests that benthic macroinvertebrates are a reservoir for VHSV IVb in infected systems. If there are environmental reservoirs for VHSV IVb in infected systems, they are likely unevenly distributed. Findings of this study add to our understanding of the seemingly complex ecology of this deadly and economically detrimental virus.Received February 22, 2016; accepted October 16, 2016 Published online February 6, 2017 相似文献
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本文根据遗传学中基因传递规律及概率论中贝叶斯定理 ,假定某座位一对等位基因处于哈代 -温伯平衡状态时 ,由后代基因型估计亲代基因型的原理和方法 相似文献
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Chickens were shown to be natural predators of ticks. Rhipicephalus appendiculatus were recovered in large numbers from the crops and gizzards of chickens which had scavenged for 30 min-1 h among tick-infested cattle. Other ticks recovered were Amblyomma variegatum and Boophilus decoloratus. The numbers of ticks recovered ranged from 3 to 331, with an average of 81 per chicken. Cattle facilitated the predation of ticks by certain behavioural actions. Chickens also picked up both engorged and unengorged ticks seeded on vegetation, but unengorged ticks were preferred. The possibility of tick predation by chickens forming a viable biological control component in an integrated tick management system in Africa is discussed. 相似文献
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Experimental Transmission of Corynebacterium pseudotuberculosis Biovar equi in Horses by House Flies 下载免费PDF全文
M. Barba A.J. Stewart T. Passler A.A. Wooldridge E. van Santen M.F. Chamorro R.C. Cattley T. Hathcock J.A. Hogsette X.P. Hu 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2015,29(2):636-643
Background
The route of Corynebacterium pseudotuberculosis infection in horses remains undetermined, but transmission by insects is suspected.Objectives
To investigate house flies (Musca domestica L.) as vectors of C. pseudotuberculosis transmission in horses.Animals
Eight healthy, adult ponies.Methods
Randomized, controlled, blinded prospective study. Ten wounds were created in the pectoral region where cages for flies were attached. Three ponies were directly inoculated with C. pseudotuberculosis. Four ponies were exposed for 24 hours to 20 hours C. pseudotuberculosis‐inoculated flies. One negative control pony was exposed to noninoculated flies. Ponies were examined daily for swelling, heat, pain, and drainage at the inoculation site. Blood was collected weekly for CBC and biochemical analysis, and twice weekly for synergistic hemolysis inhibition titers.Results
Clinical signs of local infection and positive cultures were observed in 7/7 exposed ponies and were absent in the negative control. In exposed ponies, peak serologic titers (1 : 512 to 1 : 2,048) were obtained between days 17 and 21. Seroconversion was not observed in the negative control. Neutrophil counts were higher in the positive and fly‐exposed groups than in the negative control (P = .002 and P = .005) on day 3 postinoculation. Serum amyloid A concentrations were higher in the positive control than in the negative control and fly‐exposed ponies on days 3 (P < .0001) and 7 (P = .0004 and P = .0001). No differences were detected for other biochemical variables.Conclusions and Clinical Importance
House flies can serve as mechanical vectors of C. pseudotuberculosis and can transmit the bacterium to ponies. 相似文献8.
《Journal of aquatic animal health》2013,25(3):282-286
Abstract Two related retroviruses, designated walleye epidermal hyperplasia virus type 1 (WEHV1) and type 2 (WEHV2), have been identified in discrete epidermal hyperplasia skin lesions from adult walleyes Stizostedion vitreum. A transmission experiment was conducted in an effort to provide evidence for a viral etiology and to develop a model for pathogenesis studies. Cell-free filtrates derived from discrete epidermal hyperplasia lesions and known to harbor WEHV1 and WEHV2 were injected into young-of-the-year (age-0) walleyes. Discrete epidermal hyperplasia developed in 97% of walleyes inoculated with lesion filtrates; whereas those injected with a cell-free filtrate of normal walleye skin did not develop lesions. The presence of WEHV1 or WEHV2 was detected by polymerase chain reaction (PCR) assay. Amplified DNA products from the PCR assays indicated the presence of viral sequences in 100% and 69% of the skin lesions for WEHV2 and WEHV1, respectively. 相似文献
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《Journal of aquatic animal health》2013,25(3):214-219
Abstract Walleye dermal sarcoma was transmitted under experimental conditions to yellow perch Perca flavescens. Fish (20 weeks posthatch) were challenged with cell-free tumor filtrates by topical application on the right flank and then held for observation for 25 weeks in 15°C dechlorinated municipal water. Additional treatment groups included yellow perch challenged with cell-free filtrates of walleye discrete epidermal hyperplasia, yellow perch discrete epidermal hyperplasia, normal yellow perch skin (control), and normal walleye skin (control). Walleye dermal sarcoma was first observed on yellow perch at 20 weeks postexposure, at which time the tumors were small (1–2-mm), slightly raised masses on the right flank of the fish. At the end of the 25-week study, walleye dermal sarcoma was grossly observed in 42% (22 of 53) of the remaining fish and was confirmed by microscopic examination in an additional 29% (9 of 31). Gross and microscopic evaluation of fish at 25 weeks postexposure did not reveal development of lesions in any of the other treatment groups. This study extends the host range of experimentally transmitted walleye dermal sarcoma virus to include the yellow perch. 相似文献
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本试验扩增了波尔山羊、南江黄羊和承德无角山羊3个品种113个个体的Callipyge基因长度为493 bp的片段。 经测序,发现一个SNP位点,第184 bp处C→T。对Callipyge限制性酶切位点(Fok I)的PCR-RFLP的多态性进行分析,在波尔山羊和南江黄羊两个品种中表现多态性,得到CC、CT和TT 3种基因型,波尔山羊群体中基因型频率分别为0.6571、0.3143、0.0286,南江黄羊群体中基因型频率分别为0.8947、0.1053、0.0000,而承德无角山羊全部为CC基因型。研究结果提示184C→T可能与山羊双肌性状有关。 相似文献
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S. R. SANNA A. CARTA & S. CASU 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2002,119(3):190-199
Genotype by environment interaction (GEI) for milk yield (ME) wasinvestigated by analyzing 40 140 first lactation records performed in 538 flocks. Flock–year effects from national genetic evaluation were used to define low (L), medium (M) and high (H) yielding environments. Differences observed between adjacent subsets were approximately 20% of the trait overall mean. Sire variance components estimated using multitrait analysis were 58, 82 and 149% of the estimate from the complete dataset (L, M and H, respectively) and genetic correlation coefficient between extreme subsets was 0.66, lower than genetic correlations obtained from randomly sampled subsets. Rank correlation coefficients between estimated transmitting abilities (ETA), obtained independently within L, M and H subsets for 71 AI rams having at least 10 daughters per subset, were lower than one (ranging from 0.42 to 0.56). These results strongly supported the existence of GEI for milk yield in Sarda sheep flocks. The influence of GEI on phenotypic responses in flocks differing in yield level could be due to a reduced expression of genes under conditions of restricted environmental opportunity. Splitting the selection scheme according to farming conditions does not seem a suitable solution for the Sarda breeding program. Thus, to provide farmers with genotypes suitable to exhibit a good phenotypic expression in different conditions, the selection across all environments, in which the descendants are expected to perform, still seems the best option. 相似文献
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Spores of Encephalitozoon cuniculi were recovered from foetal and placental tissues from blue fox females orally inoculated with the parasite. The results provided evidence for transplacental transmission of the causative agent of fox encephalitozoonosis. 相似文献
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《Journal of aquatic animal health》2013,25(3):157-161
Abstract The effects of temperature on experimental transmission of dermal sarcoma, a spontaneous tumor of adult walleyes Stizostedion vitreum to fingerling walleyes was determined. Test temperatures were 10, 15, and 20°C. Three-month-old walleyes were inoculated intramuscularly with a cell-free filtrate from a dermal sarcoma collected from an adult walleye in the spring of the year. Tumors were first grossly visible in fish held at 15°C at 8 weeks postinoculation. At 12 weeks postinoculation, all fish were euthanized and examined for presence of tumors. Tumor transmission was most successful at 15°C, followed by that at 20°C; many fish maintained at these temperatures had grossly visible tumors. Although the majority offish held at 10°C also had tumors, tumors in these fish developed to a lesser degree than those observed in fish held at the higher temperatures. 相似文献