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卵泡从原始卵泡发育为成熟卵泡,直至排卵、黄体发育等过程都受到精密的调控,产生大量的优势卵泡是绵羊产多羔及实现快速扩繁的关键因素。研究发现,相关信号通路和转录因子通过影响绵羊卵泡中卵母细胞、颗粒细胞的生长,进而调控卵泡的发育成熟,对这些信号通路进行深入了解,有助于探索卵泡发育的调控机制,早日实现绵羊高效繁育。Notch是卵泡发育过程中发挥重要作用的高度保守信号通路,PI3K/AKT/mTOR信号通路各成员都是广泛存在于细胞内的信号转导分子,在卵泡发育早期发挥了主要作用,还有间隙连接(gap junction,GJ)和跨带突触(transzonal projections,TZPs)等物理连接方式,在细胞间的交流通讯起到重要作用。作者详细介绍了Notch信号通路、PI3K/AKT/mTOR信号通路、间隙连接及跨带突触的结构功能在绵羊卵泡发育中的调控作用,为进一步探明绵羊卵泡发育的调控机制提供参考。 相似文献
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Approaches to pathogen-mediated resistance breeding against plum pox potyvirus in stone-fruit trees1
A. DA CMARA MACHADO E. KNAPP H. PÜHRINGER G. SEIFERT V. HANZER H. WEISS H. KATINGER M. LAIMER DA CMARA MACHADO 《EPPO Bulletin》1994,24(3):697-704
In a programme for developing systems which allow the transfer of foreign genes into apricot cultivars, we have tested cotyledons of immature embryos, somatic embryos and leaf discs. Apricot plants have been transformed, and then regenerated, with Agrobacterium tumefaciens strain LBA 4404 containing various binary plasmids: pBinGUSint, carrying the marker gene β-glucuronidase (GUS), and pBinPPVm, carrying the coat-protein gene of plum pox potyvirus (PPV). The marker gene GUS was used for visual evaluation of the efficiency of the transformation system. The coat-protein gene was used in the hope of introducing coat protein-mediated resistance to one of the most important stone-fruit pathogens in Europe and the Mediterranean area. 相似文献
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Macoon B Sollenberger LE Moore JE Staples CR Fike JH Portier KM 《Journal of animal science》2003,81(9):2357-2366
Quantifying DMI is necessary for estimation of nutrient consumption by ruminants, but it is inherently difficult on grazed pastures and even more so when supplements are fed. Our objectives were to compare three methods of estimating forage DMI (inference from animal performance, evaluation from fecal output using a pulse-dose marker, and estimation from herbage disappearance methods) and to identify the most useful approach or combination of approaches for estimating pasture intake by lactating dairy cows. During three continuous 28-d periods in the winter season, Holstein cows (Bos taurus; n = 32) grazed a cool-season grass or a cool-season grass-clover mixture at two stocking rates (SR; 5 vs. 2.5 cows/ha) and were fed two rates of concentrate supplementation (CS; 1 kg of concentrate [as-fed] per 2.5 or 3.5 kg of milk produced). Animal response data used in computations for the animal performance method were obtained from the latter 14 d of each period. For the pulse-dose marker method, chromium-mordanted fiber was used. Pasture sampling to determine herbage disappearance was done weekly throughout the study. Forage DMI estimated by the animal performance method was different among periods (P < 0.001; 6.5, 6.4, and 9.6 kg/d for Periods 1, 2, and 3, respectively), between SR (P < 0.001; 8.7 [low SR] vs. 6.3 kg/d [high SR]) and between CS (P < 0.01; 8.4 [low CS] vs. 6.6 kg/d [high CS]). The period and SR effect seemed to be related to forage mass. The pulse-dose marker method generally provided greater estimates of forage DMI (as much as 11.0 kg/d more than the animal performance method) and was not correlated with the other methods. Estimates of forage DMI by the herbage disappearance method were correlated with the animal performance method. The difference between estimates from these two methods, ranging from -4.7 to 5.4 kg/d, were much lower than their difference from pulse-dose marker estimates. The results of this study suggest that, when appropriate for the research objectives, the animal performance or herbage disappearance methods may be useful and less costly alternatives to using the pulse-dose method. 相似文献
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简要概述了牧草遗传转化方向及牧草转基因所取得的主要贡献,介绍了牧草遗传转化三种方法,并就今后的发展前景和转基因育种生物安全问题做了初步探讨。 相似文献
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Karol Fike Mark F Spire 《Veterinary Clinics of North America: Food Animal Practice》2006,22(2):305-320
Until recent years, relatively little attention has been given to beef cattle transportation management and research in the United States As oulined in this article, it is clear that there are significant physiologic changes occurring in cattle as a result of transport and handling. These physiologic changes encompass, among others, effects on immune system function, disease incidence, and carcass quality. Significant advancements have been made during the past decade in the use of appropriate cattle-handling techniques, facility design,and research promoting our understanding and the attenuation of transport stress. Many issues surrounding livestock transport, such as temperature and ventilation during transit, use of rest stops, pretransit feeding regimens, and incidence of disease transmission via transport vehicles, need further research to enable continued provision of science-based recommendations to the livestock and transportation industries. 相似文献
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A. M. PIRES M. F. MAGALHÃES L. MOREIRA DA COSTA M. J. ALVES & M. M. COELHO 《Fisheries Management and Ecology》2008,15(1):49-58
Abstract The effects of an extreme flash flood on the native fish assemblages across a Mediterranean catchment in Southwest Portugal were investigated. The fish community structure and habitat were surveyed at 10 sites pre- and post-flood. Overall species richness and rank abundances changed little after the flood, despite there being a consistent decline in the abundance of small cyprinids. Pre- and post-flood habitat correlates of abundance changed for at least some species, and variability in assemblage structure was associated with flood, depth and pH. These results indicate that extreme floods occurring early in the wet season may have little disruptive effects on the overall structure of native fish assemblages in Mediterranean streams, although may at least partially influence population dynamics for some species. Habitat quality and complexity are likely to play a role in mediating species responses to flooding. 相似文献