Constant Light Exposure Causes Dissociation in Gonadotrophin Secretion and Inhibits Partially Neuroendocrine Differentiation of Leydig Cells in Adult Rats

The objective of this work was to study the changes that occur in the Leydig cells of rats exposed to continuous light. The laboratory rat is considered a non-photoperiodic species because exposure to short photoperiod has little or no effect on the reproductive status. However, exposure of adult female rats to constant light induces polycystic ovaries, indicating that extreme changes in the photoperiod affect the reproductive function seriously. Adult male rats were placed under continuous light conditions for a duration of 15 weeks. After this period, the animals were killed and testicles were dissected and processed by routine histologic protocols. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) serum levels were determined by radioimmunoassay (RIA). The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A, S-100 protein, P substance, synaptofisin, neurofilament protein-200, gliofibrillary acidic protein and neurone-specific enolase were used. The mean LH serum concentration was significantly lower, while the mean FSH level was significantly higher in treated animals. The expression of S-100, NSE, CrA, SP and SYN was significantly lower in treated animals. In conclusion, the constant light exposure acting directly at the pituitary level decreases LH secretion. The increased FSH secretion may be due to a partial reduction of the negative androgen feedback in the pituitary gland. Moreover, the constant light exposure affects the expression of some immunomarkers in Leydig cells, possibly because of the changes found in the gonadotrophin level and feedback mechanism.     

激素对青海云杉和祁连圆柏嫩枝扦插条生长的影响

以粘土为基质,采用全光照人工间歇式喷雾装置,用IBA,ABT和GGR 3种不同浓度浸泡时间组合的植物激素,对不同株龄的青海云杉和祁连圆柏插穗进行处理,结果表明,青海云杉和祁连圆柏插穗成活率最大值均出现在植物激素ABT 200mg/L,处理200min时,当ABT浓度过大时,对插穗根系生长具有明显的抑制作用;植物激素对插穗根系生长状况的影响表明:不同激素处理的插穗生根率、根长、生根数、根系效果指数差异较为显著,生根率为ABTIBAGGR,不同株龄插穗生根对激素的响应结果表明:青海云杉插穗根系生长情况受母株株龄影响较大。     

土壤类型对沙葱幼苗出土和生长的影响

通过盆栽试验研究砂土、壤土、砂壤土、上砂下壤和上壤下砂5种不同土壤类型对沙葱出苗及幼苗生长的影响。结果表明,沙葱出苗率与土壤透气性显著正相关,砂土透气性好,沙葱出苗率最高;幼苗生长不仅与土壤透气性有关,而且与土壤养分含量有关,不同土壤类型对沙葱的叶粗、根数、地下部鲜重和干重影响显著。砂壤土中沙葱生长各指标最优,上砂下壤次之。     

Long-term agroecosystem experiments: assessing agricultural sustainability and global change

Long-term agroecosystem experiments can be defined as large-scale field experiments more than 20 years old that study crop production, nutrient cycling, and environmental impacts of agriculture. They provide a resource for evaluating biological, biogeochemical, and environmental dimensions of agricultural sustainability; for predicting future global changes; and for validating model competence and performance. A systematic assessment is needed to determine the merits of all known experiments and to identify any that may exist in tropical and subtropical environments. The establishment of an international network to coordinate data collection and link sites would facilitate more precise prediction of agroecosystem sustainability and future global change.     

家蚕60Co-γ射线诱发油蚕的遗传学研究

用^60Co-γ射线照射家蚕羽化前2－3日雌蛹,羽化后与未经照射的雄蛾交配制种,于F3群体中发现了一种双亲没有的新性状个体－高度油蚕。其幼虫皮肤透明度高,但没有其他高度油蚕的致死性,经多代饲养,体质强健,生殖力也正常。对其进行遗传分析和连锁检索,结果：该油蚕为常染色体上的隐性基因突变;与红色卵（re）连锁,属于第5连锁群;其油蚕性比中国油（oc)高,与oc杂交后代均为油蚕,确定其基因座位是：5－40.8。基因符合命名为：oc^co。     

民勤绿洲沙地系统特征及"退耕"建议

以民勤绿洲退耕地为研究对象,从民勤绿洲耕地退耕背景及特点出发,阐述了民勤绿洲沙地系统特征,并提出了退耕地生态恢复建议.认为民勤绿洲沙地系统存在水资源短缺、林牧业用地比例偏低、农业用地面积与水资源活动紧密相连的特点;民勤耕地退耕是当前水资源危机解决的关键.退耕地生态治理的意义在于变退耕地生态恢复区为新的防风阻沙林区,从而加强绿洲防护,也充当了减少水资源利用的生态减压区角色,更调节了当地农业产业结构和行业结构;提出有顺序条理化退耕,重点治理风沙口退耕地,退耕前采取植被恢复措施,政府制定、协调退耕地植被恢复各项工作的建议.     

播种密度对沙葱生长的影响

播种密度对沙葱产量、高生长和粗生长的研究结果表明,播种密度对沙葱产量和高生长有显著影响,这种影响是稳定可靠的;播种密度对粗生长的影响不显著,原因可能是观测方法及采用标准不当所致。通过拉丁方试验设计, 沙葱丰产栽培的适宜播种密度为株行距5 cm×15 cm。     

蚕学专业"互联网+"教学改革初探及调查分析

为了探索新型教学体系,拓展学生实践教学活动,以蚕学专业课程体系中的代表课程为例,建设"互联网+"教学资源,组建教学队伍和创新"互联网+"教学评价体系.通过"互联网+"网络课程教学实践1年后,对105名本科学生进行问卷式调查,从学生对网络课程的需求、认知、务件、意见反馈和实际教学效果等方面分析了基于互联网的教学模式与传统课堂教学的优势和弊端,以期促进蚕学专业本科教学质量不断提升.结果 显示,学生具有网络教学配合和补充课堂教学的需求,具备通过网络教学进行学习的条件,但由于蚕学课程大多专业实践性很强,学生更愿意接受线上线下的混合式教学模式和翻转课堂教学形式,而且这两种教学方式更有利于教师对教学效果的掌控,更有利于学生巩固基础知识,形成系统的知识和技能,网络教学可以作为辅助教学方式.     

夏枯草抗菌成分的提取及其抗菌效果研究

研究确定夏枯草有效抗菌成分的最佳提取工艺条件为料水比1：10,浸提温度90℃,浸提时间60min,提取物最大吸收波长为280m。抑茵效果试验表明,夏枯草提取液对大肠杆菌、金黄色葡萄球菌、枯草杆菌、青霉和黑曲霉都有一定抑菌作用,最低抑菌浓度分别为1．2％,1．6％,0．6％,0．8％和0．8％(mL/100mL)。