表观遗传学在家养动物遗传育种中的应用

表观遗传学(Epigenetics)是指DNA序列没有变化,而基因表达或表型却发生了可遗传并潜在可逆的改变,对动物的生长发育、疾病抗性、繁殖等性状的表达起到了重要的调控作用。由于表观遗传学起到了解释传统遗传学对性状变异无法解释的作用,因此,近20年来,其在家养动物育种领域的研究速度极为迅速。文中综述和分析了表观遗传学在猪、牛、羊和鸡等传统家养动物育种领域的研究现状及相关技术的发展趋势,将对全面了解家养动物经济性状及优异性状形成的分子机制,拓展改善经济性状的育种手段提供理论依据。     

幼犬性格的行为测试

正犬是最早被人类驯化的动物,具有对主人绝对的忠诚及高度的依恋性、服从性及高智商等特点,所以成为了为人类服务的特种工具;同时,犬作为感情动物、人类的伴侣,能给人们带来愉悦,因而,不同品种和体型的犬开始大量走入寻常百姓人家,饲养宠物犬也成为了一种时尚。选择什么品种、何种体型的犬,最好要先了解它的品性。而无论那个品种的犬,它的后代出生后     

全基因组重测序在鸡中的应用和研究进展

高通量测序技术的出现不仅推动了生命科学的发展进程,为许多生命机制的解析提供了技术支撑,也为基因组学研究中曾经未解的一些难题带来了新的解决方法。随着基因组研究水平的不断深入,越来越多家养动物的基因组信息被逐渐公布,极大地推动了家养动物重要性状在全基因水平上的研究进程。自鸡的基因组序列信息公布以来,重测序技术被大量运用于基因组选择以及由基因组序列差异导致的鸡群体结构、遗传多样性、进化机制、重要经济性状等方面的研究。本文对全基因组重测序原始数据的处理、序列比对、变异检测、测序深度进行阐述,综述了鸡的重要表型性状、遗传进化、基因组选择、蛋品质、肉品质、生长性状等的重要研究进展,并分析了当前鸡基因组研究面临的问题和挑战。     

长沙城区犬猫弓形虫病血清学检测

<正>弓形虫(Toxoplasmosis)是由龚地弓形虫(Toxoplasma gondii)引起的一种人和动物共患的、寄生在细胞内的原虫病。由于对人类危害很大,所以备受人医工作者的重视。报道称国内孕产妇弓形虫感染率为4.3%²6.1%[1],但人类只是弓形虫的中间宿主,猫科动物才是其终末宿主[2]。许多家养动物如猪、犬等都是弓形虫的中间宿主。近年来市民饲养犬猫数量不断增加,因此对犬猫进行弓形虫的研究显得很重要。目前全国有些地区对弓     

昆明犬IGF2基因克隆、生物信息学分析及其时空表达研究

【目的】 克隆昆明犬胰岛素样生长因子2（IGF2）基因并研究其序列特征及时空表达规律,为工作犬体型及生长发育相关研究提供基础资料。【方法】 采用PCR法扩增昆明犬IGF2基因CDS区,运用生物信息学分析预测昆明犬IGF2蛋白的结构与功能;利用实时荧光定量PCR技术检测IGF2基因在2.5月龄昆明犬心脏、肝脏、脾脏、肺脏、肾脏及大腿内侧肌肉和不同年龄段肝脏中的表达情况。【结果】 昆明犬IGF2基因CDS区全长717 bp,编码238个氨基酸;系统进化树分析显示,昆明犬IGF2基因与赤狐的遗传距离最近,与鸡的遗传距离最远。生物信息学分析表明,IGF2蛋白分子质量为26.46 ku,理论等电点为9.61,无信号肽和跨膜结构,属于亲水性非分泌蛋白;主要分布于细胞核（47.8%）和线粒体（17.4%）,存在23个磷酸化位点;该蛋白的二级结构以α-螺旋和无规则卷曲为主,三级结构与二级结构预测结果相符。组织表达谱分析显示,IGF2基因在2.5月龄昆明犬肝脏中相对表达量最高,且极显著高于肾脏、肺脏及肌肉组织（P<0.01）;仔犬期（2.5月龄）肝脏中的IGF2基因的表达量极显著高于幼犬期（6月龄）、青年期（1岁）及成年期（1.7和2.5岁）（P<0.01）。【结论】 本研究成功克隆昆明犬IGF2基因,并发现IGF2在多个组织广泛表达,在肝脏中的表达量最高,可为深入探讨昆明犬IGF2基因在生长发育中的调控机理提供参考。     

家养动物数量性状全基因组关联研究进展

全基因组关联分析是一种旨在充分利用群体水平的连锁不平衡,以高密度SNP芯片为技术基础,在全基因组范围内定位影响表型性状的遗传因素的遗传分析方法。对群体分层的主要检测方法、基于单标记线性混合模型策略的GWAS分析方法研究进展及全基因组关联分析样本量的估计予以综述,为家养动物数量性状的主效QTC定位提供参考。     

IGF-1基因变异与犬体型及衰老的关系

体型较大往往是预测哺乳动物寿命较长的最佳指标之一,与此形成鲜明对比的是,有相当多的证据表明,在物种内部,体型较大的个体实际上寿命较短。这种体型增大的明显代价在犬上表现得尤为突出,人工选择导致犬种间体型相差近2个数量级,平均寿命相差2倍。胰岛素样生长因子1(IGF-1)是GH/IGF-1和IIS(insulin/IGF-1)通路中关键的调控基因,对各种生物的生长、发育、寿命以及代谢均具有重要作用。IGF-1与犬的体型和寿命都有着千丝万缕的联系,犬可作为一种研究IGF-1基因变异与体型大小和寿命之间关系的模型。论文综述了IGF-1基因变异与犬体型及衰老的研究,为抗衰老相关研究提供参考。     

MC3R和MC4R基因多态性位点与犬体型性状的关系

为了探讨犬MC3R和MC4R基因多态性与体质量等体型性状的关系,本研究利用PCR-RFLP、AS-PCR方法对已培育的北方实验用犬MC3R基因A167T,MC4R基因T101N多态性位点与体质量、体长、身高、胸围等体型指标的关系进行分析.结果显示,这2个多态性位点的基因型与犬的体质量、胸围和体质量指数(BMI)等呈显著性相关.另外,方差分析显示MC3R和MC4R合并基因型对体质量、胸围和体质量指数影响显著,MC3R和MC4R基因对体型性状的影响有协同作用.结果表明,MC3R、MC4R基因可以作为犬体型性状的候选基因,可选不同MC3R和MC4R合并基因型的犬用于培育小型或大型实验用犬.     

畜禽生长激素受体基因的研究进展

生长激素受体（GHR）是一种跨膜糖蛋白,GHR可以与脑垂体产生的生长激素（GH）相结合,启动细胞内的信号转导机制,增加胰岛素样生长因子-1(IGF-1)的表达,促进细胞增殖,最终发挥调控动物骨骼肌生长发育的作用。本文综述了GHR基因的功能与结构、GHR基因在羊、牛、猪、家禽及其他动物中的最新研究进展，为更深入研究GHR基因对动物生产性能的影响提供参考。     

野生动物疫病与公共卫生

目前,现代医学所认知的1145种人类传染性疾病中,有62%的疾病来源于动物.动物源性疫病作为一个重要的人类公共健康问题,日益受到世界各国的重视.近年来,随着人们对传染性疾病中溯源研究的深入,发现野生动物疾病与人类的健康有着直接关系.如挨博拉病毒源于非洲东部的类人猿.人类免疫缺陷病毒也源于野生灵长类动物.SARS来源于蝙蝠.禽流感病毒来源于野生水禽,且通过家禽而传染给人类.另一方面野生动物可能受到人类或家养动物疫病的威胁.例如,国家公园的狮子群体由于感染犬瘟热而即将面临着绝种,而该病是通过家养犬传染给狮子的;还有现在非洲的野狗正在受源于家养犬的狂犬病的侵袭,因而对于许多濒危野生动物来说,野生动物疾病会加速其灭绝的速度.因此人类必须加强对野生动物源性疫病的充分认识和重视,建立跨学科、国际间的整体合作和交流,实施疫病的监测、实验研究和防控工作,把野生动物源性疫病作为全球疾病预防、监测、监控和防治的一个重要组成部分,为人类的健康及人类社会的进步提供保障.     

家犬基因组及表型特征的遗传研究进展

犬具有丰富的遗传多样性,犬、人和鼠3种生物的基因组分析发现,犬与人、鼠的保守性非常高。犬的特殊群体结构使其成为研究形态、行为等多样性、哺乳动物进化遗传基础和疾病的良好模型。本文就家犬起源进化、基因组结构、犬表型特征的遗传变异、基因定位等研究进展做一综述,以期为犬遗传育种研究提供理论基础,并为人类疾病的预防、诊断和治疗提供新的思路与方法。     

Genetic influences on the outcome of the progeny tests for behaviour traits in Hovawart dogs

The objective of the present study was to evaluate the importance of genetic and environmental sources of variation for results of behaviour tests in young dogs being used for progeny evaluations in the Hovawart dog. In total, 4,113 dogs born in 1995 to 2000 have been available for these analyses. Traits used were appearance, hunting affinity, group of people, acoustical and optical influences and temperament. Variance components were estimated using multivariat linear animal models and Restricted Maximum Likelihood (REML). The models included test-year-season, sex, litter size, age and inbreeding coefficient of the animal as fixed effects. Additive genetic effects of the animal, permanent environmental effect of the litter and the effect of the kennel were considered as random factors. The sex of the dog was significant for all traits. The age of the dog at the test significantly influenced the traits temperament and appearance. Test-year-season was significant for all traits except for appearance, whereas the inbreeding coefficient of the animal was significant for acoustical influences and temperament. Litter size did not influence any of the traits significantly. The estimated heritabilities of the behaviour traits analysed here ranged from h2 = 0.03 to h2 = 0.11 with standard errors of up to 0.03. The additive genetic correlations between most of the traits were moderately to highly positive (rg = 0.16 to rg = 0.91). The traits hunting affinity and appearance showed an additive genetic correlation close to zero (rg = 0.03). Negative additive genetic correlations were found between temperament and appearance as well as acoustical and optical influences (rg = -0.14 to rg = -0.4).     

Dog and owner characteristics affecting the dog–owner relationship

The nature of the relationship between companion dogs and their owners has important impact on the effect of life for both dog and owner. Identifying factors that affect the dog–owner relationship will assist the understanding of how the successful relationship is achieved and how the less successful relationship is mended, with potential benefits for the welfare of both species. In the present study, we investigated the effect of several dog and owner characteristics, including the personality of the dog, on the dog–owner relationship as measured by the Monash Dog Owner Relationship Scale (MDORS). Data were collected by inviting owners of dogs that had been tested on the Danish Dog Mentality Assessment (DMA) to answer an online questionnaire. We were able to match 421 owner answers with their dogs' DMA test results. The questionnaire consisted of the 28 items of the MDORS, as well as questions about the owners and their dogs. Using factor analysis, 5 dog personality traits could be derived from the dogs' test results on the DMA. The predictive value of questionnaire-based owner and dog variables and the 5 dog personality traits on the dog–owner relationship was tested using multiple linear regressions: 1 for each of the 3 subscales of the MDORS. Overall, the variables investigated only predicted a small proportion of the variance in MDORS scores, and owner characteristics appeared to influence the dog–owner relationship more than dog personality traits did. We found that children in the family and using the dog only for company were negatively associated with the owners' perception of the relationship with their dogs. The only dog characteristics to predict the dog–owner relationship were fearfulness and fear-related behavior problems.     

Genetic analysis of markers of the working test for herding dogs 2. Undesired behavior traits

The objective of the present study was to analyse the occurrence of undesirable behaviour traits registered on sheep dog trials in order to evaluate the importance of genetic and environmental sources of variation and to draw conclusions for breeding purposes. The data analysed consisted of 2745 test results recorded at 48 sheep dog trials carried out in Germany from 1994 to 1998, which were attended by 337 sheep dogs. Variance components of undesirable behaviour traits were estimated applying Restricted Maximum Likelihood methods. Additive genetic effects, permanent environmental effects of the animal and the effect of the handler were treated as random factors. Additionally, the linear multivariate animal model included the fixed effects of the age of the dogs at the sheep dog trial, sex, the level of difficulty of the exercises as well as the event itself, the starting number of the dog, the number of the dogs' tests at the particular event and the number of dogs presented on sheep dog trials by their handlers. The inbreeding coefficient was regarded as a linear covariate. The analyses were performed using all sheep dog trial classes and for each of the three classes separately. Age of the dog and starting number did not explain a significant proportion of variance for traits analysed, whereas the event of the sheep dog trial and partly the number of dogs per handler were of significant importance. The estimated heritabilities for the undesirable behaviour traits ranged from h2 < or = 0.001 to h2 = 0.07 with standard errors in the range between 0.001 and 0.06. The possibilities to select against undesired behaviour traits appear to be rather limited given the heritability estimates and the low number of progeny.     

Urban domestic dog populations as a source of canine distemper virus for wild carnivores in the Coquimbo region of Chile

Urban areas can support dog populations dense enough to maintain canine distemper virus (CDV) and can be a source of infection for rural dogs and free-ranging carnivores. The aim of this study was to investigate the relationships between urban and rural domestic dog and wild carnivore populations and their effects on the epidemiology of CDV to explain retrospectively a CD outbreak in wild foxes in 2003. From 2005 to 2007 a cross-sectional household questionnaire survey was conducted in Coquimbo and Ovalle cities, in three towns and in rural sites along two transects from these cities to the Fray Jorge National Park (FJNP) in the Coquimbo region, Chile. Blood samples were collected from unvaccinated dogs at surveyed households and from free-ranging foxes in rural areas along the transects. The seroprevalence of CDV in domestic dogs was higher in urban than in rural areas and in the later was highest in dogs born before 2001-2002. The seroprevalence of CDV in foxes was higher in areas closer to human settlements. A high seroprevalence in dogs born before 2001-2002 further supports a link between CDV patterns in rural dog and fox populations. In our study area, urban dogs are proposed to be the source of CDV infection to wild carnivores. The large dog population size and density detected in Coquimbo and Ovalle provides optimal conditions for maintaining a large and dense susceptible population of dogs, which can act as a reservoir for highly infectious diseases and could have been the source of infection in the CD outbreak in wild foxes.     

Abundance of mRNA of growth hormone receptor and insulin-like growth factors-1 and -2 in duodenal and colonic biopsies of dogs with chronic enteropathies*

Repair processes of the inflamed intestine are very important for dissolution of chronic enteropathies (CE). Therefore, we examined the mRNA abundance of growth hormone receptor (GHR), insulin-like growth factors (IGF)-1 and -2 in duodenal and colonic biopsies of dogs with CE such as food-responsive diarrhoea (FRD) and inflammatory bowel disease (IBD) before and after treatment as compared with each other and healthy dogs. A clinical score (Canine IBD Activity Index = CIBDAI) was applied to judge the severity of CE. Biopsies of duodenum and colon from client-owned dogs with CE were sampled before (FRD(bef), n = 5; IBD(bef), n = 5) and after treatment (FRD(aft), n = 5; IBD(aft), n = 5). Intestinal control samples were available from a homogenous control population (n = 15; C). Intestinal samples were homogenized, total RNA was extracted, reverse transcribed and analysed by real-time polymerase chain reaction to measure mRNA levels of GHR, IGF-1 and IGF-2. Results were normalized with glyceraldehyde phosphate dehydrogenase as housekeeping gene. The CIBDAI decreased during the treatment period in FRD and IBD (P < 0.01). In duodenum, GHR mRNA levels were higher in all groups than in C (P < 0.001). Duodenal IGF-1 mRNA levels in FRD(aft) and IBD(aft) tended to be higher than in C (P < 0.1). The IGF-2 mRNA abundance in FRD(aft) was higher than in C (P < 0.05) in duodenum. In colon, mRNA levels of IGF-1 in IBD(aft) were higher than in FRD(aft) (P < 0.05) and levels differed between IBD(aft) and C (P < 0.05). In conclusion, mRNA levels of GHR, IGF-1 and IGF-2 in the gastrointestinal tract were increased during CE when compared with gastrointestinally healthy dogs. The data suggest that GHR, IGF-1 and IGF-2 are involved in gastrointestinal repair processes.     

Genetic analysis of markers of the performance test for herding dogs. 1. Performance traits

The objective of the present study was to analyse data based on records of sheep dog trials in order to evaluate the importance of genetic and environmental sources of variation and to draw conclusions for breeding purposes. The data analysed consisted of 2745 test results recorded at 48 sheep dog trials carried out in Germany from 1994 to 1998, on which a total of 337 sheep dogs had attended. Tested dogs descended from 147 sires and 201 dams, with a mean inbreeding coefficient of about 2.8%. Variance components of working traits were estimated applying Restricted Maximum Likelihood methods. Additive genetic effects, permanent environmental effects of the animal and the effect of the handler were treated as random factors using multivariate linear models. Additionally, the model included the fixed effects of the age of the dogs at the sheep dog trial, sex, the level of difficulty of the exercises as well as the event itself, the starting number of the dog, the number of the dogs' tests at the particular event and the number of dogs presented on sheep dog trials by their handlers. The inbreeding coefficient was regarded as a linear covariate. Sex of the dog and starting number did not explain a significant proportion of variance for traits analysed, whereas the event of the sheep dog trial and the starting class usually were of significant importance. The analyses were performed using all sheep dog trial classes and for each of the three classes separately. Repeatabilities of herding traits within the same event of sheep dog trial estimated from animal effect mostly varied within a range from w = 0.1 to w = 0.5 whereas repeatabilities estimated over all events of sheep dog trials mostly gave estimates from w = 0.1 to w = 0.3. The estimated heritabilities for the herding performance traits ranged from h2 < or = 0.001 to h2 = 0.13 with standard errors in the range between 0.001 and 0.08. The selection possibilities appear to be rather limited given the heritability estimates and the low number of progeny of parents.     

The dog welfare directive of 2 May 2001

As of 1 September, 2001 existing legislation regulating outdoor dog husbandry is replaced by the domestic dog welfare directive of 2 May, 2001. The new directive applies to details of housing and breeding of dogs kept indoors and as domestic companions. Thus, minimum requirements for housing, care and feeding now apply to the great majority of private dog owners. However these requirements do not apply to animals in transit, in individual veterinary treatment or to those used for scientific experimentation whose goals justify deviations from these standards. Additional regulations apply to dog breeding and showing. Puppies may not be separated from their mother and litter before eight weeks of age. "Prohibition of breeding for aggressiveness" cited in Paragraph 11b of the animal welfare law is defined, and includes various breeds and hybrids. The directive includes an index for the care and treatment of dogs by commercial breeders. After a transitional period no dogs which have been subjected to amputations at the expense of the animal's welfare in order to achieve specific features may be shown publicly. The author provides critical commentary on the regulations of the domestic dog welfare directive and points out areas which will continue to be of concern.