Sexual maturation in hens is not associated with increases in serum leptin and the expression of leptin receptor mRNA in hjpothalamus

Background： In mammals, leptin is an attractive candidate for mediating the metabolic signal and the reproductive function via the specific receptor in hypothalamus. However, till now, the role of leptin on reproduction in birds is less well established. This experiment was conducted to elucidate the role of leptin on the onset of reproduction in bird, as a first step, to detect the changes of peripheral leptin and leptin receptor mRNA expression in hypothalamus between mature and immature hens at the same age. 120 ISA brown pullets at D60 were allocated randomly into two groups, long light （LL） group being raised under artificial light regimes with incrementally increased light phase （from 8 L：]6D to 14 L：]2D） and short light （SL） group raised on consistent light （8 L：16D） for 12 wk. Results： The results showed that pullets in LL group reached sexual maturation 15 d earlier than those in SL group. Serum E2 showed a significant increase with age, but no difference was observed between two groups. Serum leptin concentration decreased significantly from D112 to D136 in LL, and was markedly higher in LL group than that in SL at D112, while there was no significant difference between two groups at D136. Leptin receptor and GnRH-I mRNA expression in hypothalamus were significantly increased with age, yet there was no significant difference between SL and LL chickens at the same age. The expression of FSH-13 and LH-13 mRNA in pituitary was increased with age but did not show significant difference between LL and gland, and decreased from D112 to D136 in LL but not groups at the same age. SL group. GnfiH-I mRNA expression was very rich in pinea n SL group, and there was no difference between two Conclusions： These results indicate that the earlier sexual maturation in hens induced by long-light regime is not accompanied with an increase in serum leptin or leptin receptor gene expression in hypothalamus, or genes expression in HPG axis.     

哺乳动物性别决定的分子模型与性别鉴定方法研究

介绍了几种哺乳动物性别决定的分子模型,阐述了性别鉴定的方法及现状,指出性别鉴定方法的研究可用于胎儿性别鉴定、司法中人性别鉴定,对性分化与发育异常等临床疾病的诊断和治疗具有十分重要的意义。     

亚洲部分稻瘟病菌的交配型和雌性能育菌株的遗传多样性分析

 用稻瘟病菌两性菌株测定中国及亚洲部分国家稻瘟病菌有性时期的交配型和雌性能育菌株 ,并用SCAR分子标记对 14 3个菌株进行PCR扩增 ,分析它们的遗传多样性 ,得到亲缘关系树状图     

LRH—A_3提高水牛第一情期受胎率的研究与推广

本文将LRH—A_3在信阳水牛上应用4年(1989～1992),筛选出了用于提高第一情期受胎率的最适宜剂量(200μg/头),推广应用1330头,第一情期受胎率(51.58％)极显著地高出对照组(26.24％)。     

不同物理措施对娃娃菜小菜蛾的诱杀效果

为给武威市高原夏菜小菜蛾的监测及绿色防控提供科学依据，选择光诱、色诱、性诱及不同组合等多种物理诱杀措施，设计16个处理，对娃娃菜田小菜蛾诱杀效果进行比较研究。结果表明，在小菜蛾成虫发生期，使用紫光灯+诱芯组合诱杀措施效果最好，单板日均诱蛾量达到224.9头，为单独使用紫光灯诱杀效果的1.6倍。小菜蛾发生期推荐使用紫光灯配合性信息素诱芯进行防治，春季小菜蛾发生较轻时可单独使用紫光灯或性信息素诱芯进行防治。     

青年期营养水平对公牛生长发育的影响

以体质量、体高、阴囊周径、睾丸容积和性成熟年龄为指标,研究青年期营养水平对后备公牛生长发育及性发育的影响。结果表明,青年期营养水平对后备公牛体质量有显著的影响(P0.05);对体高的影响具有累积性,随年龄的增加逐渐表现出来;对后备公牛性器官及性发育有显著影响(P0.05)。适宜的营养水平有利于公牛生长,较高的营养水平对公牛的生长发育的促进作用不显著,较低的营养水平可以显著抑制公牛的生长发育及性发育。     

海草有性繁殖成花诱因研究进展与展望

海草是一类生活在热带至温带浅海、完全适应海洋环境的沉水被子植物的总称。海草床作为连接珊瑚礁与红树林的纽带，具有重要的生态功能与经济价值。近年来，随着人们对海草认识的不断加深，海草的有性繁殖行为逐渐受到关注，而成花诱导是海草从营养生长向生殖生长过渡的重要环节。本文综述了海草有性繁殖中成花诱因的研究进展，探讨了温度、光照、盐度等相关因子对海草成花诱导的影响，分析了海草响应外界环境刺激与内源信号启动开花途径可能集中在光周期途径、春化途径和自发途径上。建议未来海草床保护修复工作应加强对海草有性生殖行为的研究，明确不同海域海草的集中开花和结果时间，对海草床生态系统的修复与保护具有重要意义。