Larger body size with higher predation rate

Abstract –  Many studies have reported that prey fish increase in body size with an increase in piscivore abundance, and this change may be explained mainly by two processes: release from intraspecific competition because of a reduction in the prey fish population and size-dependent selection by the piscivore. However, the evolutionary mechanism is not yet fully understood. Here, we first show the body-size dynamics of the semelparous gobiid fish Gymnogobius isaza , which is one of the prey fishes of the introduced largemouth bass, Micropterus salmoides . The data show the possibility that the goby body size might have changed in parallel to the number of largemouth bass from 1975 to 2002, which may be one of the best examples of the positive relationship between body size and predation rate. Furthermore, we explored a mathematical model to consider a body-size change of semelparous fish from an evolutionary viewpoint. The model provided the following qualitative predictions: (1) the optimal assimilation rate increases with predation pressure; (2) a rapid large-scale increase in predation pressure may exterminate the prey fish because of delayed evolution of the assimilation rate; and (3) the optimal assimilation rate increases when the prey fish is more likely to die through predation than through natural mortality or when it is difficult to grow larger because of low resource availability or insufficient foraging efficiency. Moreover, we propose a theoretical framework to evaluate the relative effects of ecological and evolutionary processes over the long term.     

千万不可忽视良种黄牛的保种问题

阐述了良种牛保种的重要意义．基因的随机漂移、选择与杂交、近交是特定基因从群体中消失的主要原因，群体及其有效含量和系统选育的科学组织是保种的重要内容。最后介绍我国良种牛的保种方法及其存在的问题，并提出解决的办法。     

PA序列下非参数回归函数估计的相合性

设{εi,i≥1}为PA序列，Eεi=0，supE（ε^2j）〈∞，对某个r〉2及占〉δ，supE｜εj｜^r＋δ〈∞，u（n）=O（n^（r-2）（r＋δ）/2δ，在PA序列误差下，讨论了非参数回归函数加权核估计的相合性．     

对当前监理工作的几点思考

监理是建设工程不可缺少的一个环节，如何重视监理工作是亟待解决的一个问题。     

PCR法克隆紫穗槐4-香豆酸:CoA连接酶全长cDNA

4 香豆酸 :CoA连接酶 (4CL)是木质素生物合成过程中重要的酶 .该文利用简并寡核苷酸PCR法结合cDNA末端快速扩增PCR法直接获得了紫穗槐 4CLAcDNA全长序列 ,避免了复杂的构建、筛选cDNA文库的过程 .先用简并PCR得到了 4CLA1片段 ,又据此片段设计反向嵌套引物 ,用RACE方法获得未知的 5′和 3′端序列 .所获得的全长 4CLAcDNA ,编码 5 40个氨基酸 .氨基酸序列同源性分析表明4CLA是典型的 4CL蛋白 ,含有预计的AMP binding位点、催化反应区和保守的Cys .     

Genetic analysis of fat‐to‐protein ratio,milk yield and somatic cell score of Holstein cows in Japan in the first three lactations by using a random regression model

We estimated the genetic parameters of fat‐to‐protein ratio (FPR) and the genetic correlations between FPR and milk yield or somatic cell score in the first three lactations in dairy cows. Data included 3 079 517 test‐day records of 201 138 Holstein cows in Japan from 2006 to 2011. Genetic parameters were estimated with a multiple‐trait random regression model in which the records within and between parities were treated as separate traits. The phenotypic values of FPR increased soon after parturition and peaked at 10 to 20 days in milk, then decreased slowly in mid‐ and late lactation. Heritability estimates for FPR yielded moderate values. Genetic correlations of FPR among parities were low in early lactation. Genetic correlations between FPR and milk yield were positive and low in early lactation, but only in the first lactation. Genetic correlations between FPR and somatic cell score were positive in early lactation and decreased to become negative in mid‐ to late lactation. By using these results for genetic evaluation it should be possible to improve energy balance in dairy cows.     

Genetic evaluation using random regression models with different covariance functions for test‐day milk yield in an admixture population of Thailand goats

The objectives of this study were to compare covariance functions (CF) and estimate the heritability of milk yield from test‐day records among exotic (Saanen, Anglo‐Nubian, Toggenburg and Alpine) and crossbred goats (Thai native and exotic breed), using a random regression model. A total of 1472 records of test‐day milk yield were used, collected from 112 does between 2003 and 2006. CF of the study were Wilmink function, second‐ and third‐order Legendre polynomials, and linear splines 4 knots located at 5, 25, 90 and 155 days in milk (SP25–90) and 5, 35, 95 and 155 of days in milk (SP35–95). Variance components were estimated by restricted maximum likelihood method (REML). Goodness of fit, Akaike information criterion (AIC), percentage of squared bias (PSB), mean square error (MSE), and empirical correlation (RHO) between the observed and predicted values were used to compare models. The results showed that CF had an impact on (co)variance estimation in random regression models (RRM). The RRM with splines 4 knots located at 5, 25, 90 and 155 of days in milk had the lowest AIC, PSB and MSE, and the highest RHO. The heritability estimated throughout lactation obtained with this model ranged from 0.13 to 0.23.     

广西猪瘟病毒E0和E2基因的克隆及序列分析

通过分析目前广西猪瘟病毒(CSFV)的E0和E2基因特征,为了解广西地区CSFV的分子流行病学、遗传变异及综合防控提供科学依据。试验采用RT-PCR方法,对阳性猪瘟样品进行CSFV的E0及E2基因的扩增,经克隆、测序后,利用DNAStar软件对序列进行比对分析,同时绘制系统遗传进化树。结果表明,从阳性猪瘟样品中成功扩增CSFV的E0及E2基因。序列比对分析发现,GX2毒株与参考毒株的E0基因核苷酸同源性在83.1%~94.1%,其推导氨基酸同源性在85.9%~99.6%;与参考毒株的E2基因核苷酸同源性为81.7%~93.7%,其推导氨基酸同源性为89.0%~97.0%;E0与E2基因均属于基因Ⅱ群。氨基酸变异位点分析表明,E0蛋白的RNase活性区域氨基酸基序位点没有发生变异;E2蛋白中15个位点上的半胱氨酸均未发生变异,但单抗识别位点S734R发生变异。遗传进化分析显示测定的GX2毒株与近年来广西CSFV流行毒株的变异趋势相似,与中国传统疫苗株HCLV、经典强毒株Shimen的同源性较低,亲缘关系较远,与广西近年来的流行毒株GXWZ02株的同源性较高,亲缘关系较近。     

农业机械推广鉴定证后监督的实践与思考

为总结利用农机证后监督工作成果,进一步创新完善监督制度,深入推进农业机械化领域“放管服”改革,回顾农机证后监督发展历程,定义为4个阶段：起步摸索阶段、常态规范阶段、创新发展阶段、完善提升阶段。介绍证后监督总体实施情况,包括监督检查内容、工作程序及历年抽查数量、完成率、抽查产品的地域分布及种类分布分析。基于结果数据分析发现整改确认后合格占比呈下降趋势、不合格占比呈上升趋势、证后监督权威日益显现等趋势性变化,并结合政策文件制修订背景分析证后监督结果趋势性变化的原因。通过深入分析不合格及整改等原因,发现获证企业对政策了解不足、对产品一致性管理不足、对证书和标志的动态管理不足、生产经营异常现象日益增多等经营管理现状。针对证后监督总体实施情况及发现问题,提出需加大抽查证书数量及产品种类、加强政策宣传及人员培训、建立信用风险分类监管制度、进一步挖掘潜力强化证后监督作用的政策建议。     

广东花生果腐病病原菌鉴定及药剂筛选试验

【目的】鉴定广东花生果腐病病原菌类型并筛选有效的杀菌剂种类,为生产上防控该病害提供参 考。【方法】采用组织分离法从大田采集的患病花生果荚中分离获得果腐病的真菌纯培养物,回接验证分离菌 株的致病性后确认其病原,通过克隆菌株的 ITS 序列并进行系统发育分析鉴定病原菌种类。采用菌丝生长速率 法测定 40% 福美双水悬浮剂、98% 噁霉灵可溶性粉剂、24% 井冈霉素 A 水剂、10% 苯醚甲环唑水分散粒剂和 10% 多抗霉素可湿性粉剂对该病原菌的抑菌效果。【结果】 从韶关采集的花生果腐病样本中分离获得 2 株病原 真菌,回接后均可以引起花生果荚腐烂,严重时导致果仁腐烂。基于菌株 ITS 序列的系统发育分析显示病原菌 为尖孢镰刀菌（Fusarium oxyspourm）和茄病镰刀菌（Fusarium solani）。供试杀菌剂中 40% 福美双悬浮剂对 2 种病原真菌的抑菌效果最好,EC50 分别为 0.001 mg/L 和 0.021 mg/L,其次是噁霉灵,EC50 分别为 0.296 mg/L 和 0.217 mg/L,井冈霉素 A 的 EC50 分别为 20.575 mg/L 和 11.185 mg/L,苯醚甲环唑和多抗霉素对 2 株病原真菌没有抑菌 效果。【结论】广东韶关地区花生果腐病主要由镰刀菌复合感染引起,以茄病镰刀菌为主,病原菌对福美双和 噁霉灵敏感,生产上可以考虑使用这两种杀菌剂防控。