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The investigation was supported by the National Institutes of Health, General Research Support Grant FR 5465 Administered through the College of Veterinary Medicine, Washington State University. 相似文献
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我国北方部分稻区稻瘟病菌群体遗传结构研究 总被引:24,自引:1,他引:24
本文利用rep-PCR指纹分析方法研究了我国北方部分稻区稻瘟病菌的单元型(haplotype)和谱系(lineage)。根据单元型和谱系组成以及优势单元型和优势谱系的变化,分析了稻瘟病菌的群体结构和遗传变异性,证实了稻瘟病菌在DNA水平上是高度异质和极易变异的。对病原菌群体的时空变化分析发现,稻瘟病菌群体的单元型和谱系因年度和地区而不同。不同年度、不同地区的稻瘟病菌亚群体间几乎无共同的单元型和谱系。对138个供试菌株的致病型分析发现,单元型和谱系与致病型之间不存在规律性的对应关系,这说明用rep-PCR方法揭示的稻瘟病菌的遗传变异很可能与致病性变异不存在必然的联系。 相似文献
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ROBERT L. TOAL DVM MS MICHAEL A. WALKER DVM GEORGE A. HENRY DVM 《Veterinary radiology & ultrasound》1986,27(4):102-108
Fifty-five bitches were examined once, at different intervals for pregnancy. Manual Papation, B-mode real-time ultrasoungraphy, and radiography were used to confirm pregnancy and to count the number of fetuses present. Predicted numbers were compared to whelping data obtained from owners. Radiography was confined to the last trimester of pregnancy and had an overall accuracy of 100% in pregnancy detection and 93% in correct litter size determination. A proor qualtiy radiograph contributed to the one incorrect count estimate. Ultrasound and palpation were used in all three trimester phases starting 3 weeks post coitus. For pregnancy detection ultrasound was 94% accurate (no false positives) and palpation was 88% accurate (one false positive). For fetal counting, ultrasound was 36% accurate and palpation was 12% accurate. Recommendations for the use of ultrasound and radiography in pregnancy evaluation are reviewed. 相似文献
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Sequential ichthyoplankton surveys were used to determine the spatial and temporal distribution of eggs and larvae over coastal spawning grounds of Atlantic cod (Gadus morhua) in Smith Sound, Trinity Bay, Newfoundland, during the spring and summer of 2006 and 2007. Egg densities showed similar patterns for both years with two peaks in abundance in spring (March–April) and late summer (late July). A clear progression of development stages (1–4) was observed in spring and summer in 2006 and summer in 2007, suggesting retention of eggs within the Sound during these periods. Modelled predictions of vertical egg distributions indicated eggs were broadly distributed near the surface during spring (March–April), but were concentrated below the pycnocline (>10 m) within the inner portions of the Sound during the summer months (July–August). Back‐calculated peaks in spawning based on water temperatures were estimated at 11 and 4 April for 2006 and 2007, respectfully, with late season peaks centred on 21–24 July for both years. Environmental data indicated cooler water temperatures and periods of high wind stress in spring, and warmer, calmer periods late summer, consistent with higher retention and faster development times on the spawning grounds later in the season. We conclude that spring and summer spawning events result in different distributions of early life stages and may lead to different distributions of juvenile and adult fish. 相似文献
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