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绵羊多胎性繁殖性状直接与绵羊的排卵数有关。本文对调控绵羊排卵数的主效基因FecB基因、FecX基因的定位、表型特征、作用机理及其候选基因的研究作一综述。 相似文献
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绵羊的繁殖性能是一种十分重要的经济性状,绵羊产羔数与每次的排卵数直接相关,绵羊卵子的生长发育受到卵巢内分泌及旁分泌的相互作用。FecB基因是羊上首个被发现的多胎主效基因,携带该基因的绵羊卵巢中BMP信号通路受到损害而活性降低,TGF-β家族部分成员失活,抑制GCs增殖并提高FSH的敏感性,有效提高绵羊的排卵率和产羔率,有利于扩大养殖规模,提高经济效益。本文对FecB基因的发现、作用机制及其对卵泡发育、繁殖能力和后代生长发育的影响,以及育种方面的应用进行综述,以期为绵羊繁殖性能提升的机理研究和育种工作等提供参考和借鉴。 相似文献
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绵羊繁殖性状候选基因的研究进展 总被引：6，自引：0，他引：6
目前，研究发现的影响绵羊繁殖性状的候选基因主要有四个，即FecB,FecX1,FecX和FecX2w，本文就这四个基因的发现，定位及其研究进展作一系统阐述。 相似文献
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Reid WA 《Journal of veterinary medical education》2007,34(4):390-395
In the United Kingdom, the medical students of yesteryear undertook a detailed pathology course, often with its own major examinations. This contributed to the increasing overload of factual information that was common in medical curricula. Following General Medical Council reports on medical education, pathology is now more fully integrated into clinical work and into problem-based learning, albeit with greatly reduced contact time with pathologists. Teaching methods have shifted from didactic presentations, such as lectures, to more varied methods, with emphasis on self-access and interactivity. Technological advances have brought well-illustrated textbooks, computer-assisted learning programs, Web resources, and electronic communication. There has been a decline in the role of museum specimens, microscopy, and, partly following a worldwide trend and partly following adverse media publicity, the traditional autopsy. Assessment methods have evolved, with integration of pathology into wider examinations. The greater drive toward increasing funding through the Research Assessment Exercise has had an adverse effect on teaching throughout universities. Despite these setbacks, the importance of pathology as a clinical discipline will ensure its continued role in medical education. 相似文献
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In a 4-year period nine dogs have been met in which there was incomplete growth of the radius. The condition was unilateral in eight dogs and bilateral in one. Two were littermates. The defect is due to premature cessation of growth of the distal growth plate of the radius but the cause of this is not precisely known. It is recognized by characteristic radiographic changes in radius length, elbow joint space and premature closure of the distal growth plate of the radius. A method of surgical treatment has been devised and has proved beneficial in five dogs. Zusammenfassung. In einer Vierjahresperiode wurden neun Hunde beobachtet, bei denen ein unvollständiges Wachstum des Radius vorlag. Bei acht Hunden war der Zustand nur auf einer Seite zu finden, bei einem Hund auf beiden Seiten. Zwei der Hunde gehörten zum gleichen Wurf. Der Mangel ist auf verfrühte Wachstumseinstellung der distalen Wachstumsplatte des Radius zurückzuführen, jedoch ist die Ursache davon nicht genau bekannt. Er wird an charakteristischen radiographischen Veränderungen der Radiuslänge, des Ellbogengelenkzwischenraums und vorzeitigem Abschluss der distalen Wachstumsplatte des Radius erkannt. Es wurde eine chirurgische Behandlungsmethode entwickelt, die sich bei fünf Hunden als nutzlich erwies. Résumé. Au cows d'une période de 4 ans on a observé 9 cas de croissance incomplète du radius chez des chiens; l'anomalie était unilatérale dans 8 cas et bilatérale dans un cas; deux chiens appartenaient à la même portée. L'anomalie est due à l'arrêt prématuré de croissance de la plaque de croissance distale du radius, mais la cause n'en est pas encore connue d'une manière précise. Le diagnostic se fait par les signes radiologiques caractéristiques, modifications de la longueur du radius, de l'articulation du coude et soudure prématurée de la plaque de croissance du radius. On a élaboré une méthode de traitement chirurgical, qui s'est montrée favorable chez 5 chiens. 相似文献
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Evidence for the non-involvement of the uterus in the lifespan of the corpus luteum in the cyclic dog 总被引：1，自引：0，他引：1
Progesterone levels in peripheral blood of dogs were analysed during the cycle in which hysterectomy (n = 5) or sham surgery (n = 3) was performed as well as during the cycle of dogs (n = 5) hysterectomized at least one year prior to this study; the data were compared with the findings in control dogs (n = 3). The averages of the duration of the luteal period observed in the three experimental groups were not significantly different from those of control dogs. Immediately after surgery, the progesterone level decreased from 25 to 50% of the presurgical level, but returned to presurgical level in about four days. Prolactin levels were elevated for about 30 h after surgery. Nevertheless, the averages of the mean prolactin levels for each animal during the luteal period of the experimental groups were not significantly different from those of control dogs. It is concluded that in the dog, the uterus is not involved in the lifespan of the cyclic corpus luteum. 相似文献
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国内生态恢复研究进展 总被引：10，自引：1，他引：9
本文介绍了生态恢复的研究进展,从生态恢复的定义、退化生态系统的指标等方面进行阐述,重点对国内在恢复生态学方面的进展做了介绍。对当前的人工草地、草地农业的研究情况做了一些概述。 相似文献