Seasonal patterns of dispersal of ascospores of Cryphonectria parasitica (chestnut blight)

Infected barks of chestnut blight cankers, caused by Cryphonectria parasitica , were collected from a naturally infected orchard and incubated at different temperatures. Cankers started to discharge ascospores about a week after incubation at 15–25°C; most ascospores were collected at 20 and 25°C. When incubated at 5, 10 or 30°C, only a few cankers released a small number of ascospores and only during the later stages of incubation. However, the rate of formation of perithecia was not affected by the incubation temperature. The number of airborne ascospores was monitored using a volumetric spore trap in a chestnut orchard during 1996 and 1997. In both years, the number of ascospores trapped daily varied greatly, but in general it increased sharply from March onwards, reached a peak in May, and then declined steeply. There was a significant correlation between daily counts of ascospores and air temperature. Time-series transfer function (TF) analysis showed a positive association of the daily number of ascospores with increasing temperature, rain events and wet/humid conditions. In general, values predicted by the TF model agreed well with the observed pattern. However, a multiple regression equation based on TF analysis failed to provide a satisfactory prediction of the daily number of ascospores.     

水稻白叶枯病菌两类噬菌体性状的比较

 从感染白叶枯病的稻叶、种子和田水中先后分离到24株噬菌体,测定了它们在琼胶平板上形成噬菌斑的大小、血清学反应、热钝化温度、铁盐的钝化作用、寄主范围、一级生长曲线以及在电镜下观察它们的形态。根据测定结果,可将它们区分为两个类群。第一群称为XOP 1型,以OP-3为代表,其噬菌斑直径为3~5毫米,热钝化温度为58℃/10分钟,易为三价铁盐所钝化;寄主范围较窄;潜育期为40分钟,上升期30分钟,平均裂解量为35个。第二群称为XOP 2型,以OP-12为代表,噬菌斑小,热钝化温度68℃/10分钟,对三价铁盐不敏感,潜育期80分钟,上升期50分钟,平均裂解量为8个。它们都是蝌蚪形,但OP-3的尾部细长而不能收缩,OP-12的尾部短粗而能收缩。     

岷山红三叶总异黄酮提取方法的研究

为选择提取岷山红三叶中总异黄酮的最佳方法,本文研究了用回流法、冷浸法和索式提取法提取岷山红三叶中总异黄酮的效果.通过紫外分光光度法测定提取液中的总黄酮含量,结果表明:回流提取法提取效果优于冷浸法和索式提取法.具有安全、简便和提取率高的优点.     

母犬的异常发情

受生理、营养、疾病、年龄等因素影响,母犬往往会异常发情。如不能及时发现,将会延误配种。现将母犬常见的几种异常发情的原因及防治措施介绍如下：     

Immunolocalization and expression pattern of gpr3 in the ovary and its effect on proliferation of ovarian granulosa cells in pigs

Gpr3, a member of the G protein-coupled receptor superfamily, was known as a critical factor for the maintenance of meiotic prophase arrest in oocytes via a Gs protein-mediated pathway. The present studies were conducted to examine the ovarian immunolocalization of Gpr3, its expression pattern in different stages of fetal, postnatal and developmental pigs and its effect on proliferation of ovarian granulosa cells in pigs. Immunohistochemical analysis indicated that Gpr3 was localized in egg nests, oocytes and granulosa cells (GCs) of the follicle ranging from the primordial to Graafian stages and the corpora lutea. Staining was faintly present in the corpora lutea and weak in GCs but was strong in oocytes. Real-time PCR and Western blotting indicated that Gpr3 mRNA and protein were both present in the different ages of ovaries, and there were wavy changes in the expression levels from postpartum 1 to 180 days. Moreover, both the mRNA and protein levels of Gpr3 were upregulated significantly during follicle growth, suggesting that Gpr3 might play potential roles in regulating ovarian follicle development in the pig. MTT and flow cytometry analyses indicated that Gpr3 knockdown significantly promoted proliferation of porcine GCs while increasing the proportion of cells in the S phase and the expression of Cyclin B1 and Cyclin D2, providing new insights into how Gpr3 signaling regulates the proliferation of porcine GCs. In conclusion, the stage- and cell-specific expression pattern of Gpr3 in the porcine ovary suggested that Gpr3 might play an important role during the entire process of follicular development and luteinization.     

微生物制剂降低胆固醇研究进展

<正>胆固醇是人类生存所必需的,具有重要的生理功能,但体内过量时会造成危害。与胆固醇过量有关的动脉粥样硬化、冠心病、脑中风等心脑血管疾病已严重威胁着人类健康。随着人们生活水平的提高和膳食     

复合纤维素酶在奶牛饲料中的研究与应用

复合纤维素酶对于利用纤维素含量高的粗饲料有重要意义，本文对复合纤维素酶的作用，对反刍动物的生产性能，消化代谢的影响、以及在瘤胃中的稳定性，作用机理和使用方法及其存在的问题和发展前景等方面作一论述。     

山东地区三株鸽Ⅰ型副粘病毒的分离及鉴定

2005年在山东地区部分肉鸽养殖场出现鸽子大量死亡现象,从死亡鸽中分离到三株鸽Ⅰ型副粘病毒(SD05027,SD05028,SD05029),其鸡胚平均死亡时间(MDT)分别为69h,69.6h,81.6h;鸡脑内接种指数(ICPI)为1.31,1.43,1.48,证明此次分离的三株病毒株均属速发型新城疫病毒。应用RT-PCR技术对F基因重要功能区片段扩增后进行序列测定,分析表明,F蛋白裂解位点处的序列(112R/K-R-Q-K-R-117F)与新城疫强毒在这一区域的序列相符。与多株已报道的NDV参考株相应片段进行序列比对和基因进化树分析,将其鉴定为基因VIb型。     

通过调整家禽营养改善垫料质量及其生产性能

家禽湿垫料综合征可造成重大的经济损失。据Butchers和Miles（2009）的研究,垫料质量是家禽生产的关键要素之一。如果垫料质量未被维持在一个可接受的水平上,那么垫料内细菌负荷极高和不卫生的生长条件可能会导致鸡舍内出现异味（包括氨）增加、昆虫滋生（尤其是蝇类）、羽毛脏乱、足垫病变及胸部水泡等问题。     

畜牧产业结构调整影响因素分析

本文对畜牧产业结构影响因素进行了具体分析,认为自然资源环境、社会发展进程以及科技进步是产业结构的3大影响因素,其中自然资源环境是结构调整的基础,社会发展是动力,科技进步是支撑条件。