应用cDNA微阵列芯片技术筛选猪蛔虫性别差异表达基因的研究

采用cDNA微阵列芯片技术，从所构建的猪蛔虫雌、雄成虫cDNA消减文库分别挑取1044和1119个克隆，PCR扩增其插入片段，经纯化后点样于预先处理好的基片上（双点杂交），制备成cDNA微阵列芯片。将分别标记荧光素Cy3-dUTP和Cy5-dUTP的雌虫和雄虫cDNA探针，与制备好的cDNA芯片杂交（平行进行反标杂交试验）。根据每个点杂交后的Ratio值，筛选出双点杂交和正反标中都同时具有表达差异的基因克隆共1559个。将表达差异最明显的前831个克隆进行测序，获得720个有效序列，经生物信息学分析发现，雄虫特异表达的主要精于蛋白和雌虫特异表达的卵巢信息蛋白的基因序列多数与新杆属线虫存在同源性，有31个可能是新的ESTs。性别差异表达基因及其相关生物信息的获得为下一步研究基因功能奠定了基础。     

一株无血凝性兔出血症病毒的分离鉴定及其衣壳蛋白VP60基因的克隆和序列分析

从临床病料中分离鉴定出1株无血凝性的致病性兔出血症病毒（RHDV），命名为Yaan-1。HA试验测得该毒株原代及经兔体传3代后的肝毒在25℃、37℃和4℃时均无血凝性；但在琼脂扩散试验和对流免疫电泳中均可见分离株与常规RHDV高免血清形成清晰的沉淀线；电镜观察可见30nm左右的病毒粒子。采用RT-PCR方法将Yaan-1株的衣壳蛋白VP60基因进行了克隆测序，序列分析表明VP60基因序列全长1740bp，编码579个氨基酸，测序结果提交GenBank（注册号为DQ069280），并与世界各国的常规RHDV分离株进行比较，结果表明核苷酸同源性为90．0％～98．0％，氨基酸同源性为94．1％～99．0％，氨基酸变异多发生在衣壳蛋白C、E区；同时对Yaan-1株的分子量、等电点、疏水性、跨膜区等分子结构特征进行了分析。本研究首次报道了无血凝性RHDV中国分离株，丰富了地方毒株资源，为明确我国地方株的分子流行病学，以及对VP60蛋白分子特征研究提供了新材料。     

A-FABP 在不同鸡种中遗传多态性分析

利用PCR—RFLP技术和DNA测序检测了尤溪麻鸡、鹿苑鸡、隐性白羽鸡3个鸡种共计96只鸡的脂肪细胞型脂肪酸结合蛋白（A—FABP）第85位点和第1805位点的遗传变异。结果表明：1）在这2个位点上，3个鸡种均存在变异，外来品种隐性白羽鸡以杂合子Cc居多；地方鸡种以cc居多，3个鸡种均含有较高频率的等位基因c，其中以尤溪麻鸡最高，而以隐性白羽鸡最低。2）A—FABP第85位点不影响A—FABP的氨基酸序列；而第1805位点的遗传多态性影响氨基酸序列的变化：由脯氨酸变为丝氨酸，说明该多态性可能通过A-FABP基因的表达水平从而影响鸡的肉质。本试验为进一步分析A-FABP基因的遗传变异与肌内脂肪含量的关系及该分子标记在育种计划中的应用奠定基础。     

不同熟期苦荬菜的染色体数目及核型分析

苦荬菜Lactuca indica是一种优良的牧草种质资源,熟期是苦荬菜利用的重要影响因素之一。研究对2种不同熟期的苦荬菜种子根尖细胞进行冰浴处理,染色体用醋酸洋红染色制片。染色体数目和核型分析结果表明,早熟苦荬菜和晚熟苦荬菜染色体数目均为2n=2x=18,没有差异。早熟苦荬菜核型公式为2n=2x=2m 12sm 4st;晚熟苦荬菜核型公式为2n=2x=16sm 2st,存在差异。     

内蒙古天然草地退化成因的多因素灰色关联分析

选取内蒙古草地典型草原、草甸草原及农牧交错带典型区,通过对区域内影响草地退化的社会、经济和环境等因素进行定性分析,应用灰色系统理论的关联分析方法,以草地退化面积为参考数列,以牧草生长季积温、降水变率和年大风日数等气候因子,草地超载比例、人工种草与围栏草场面积、年割草量、畜棚与畜圈面积和牧民人均收入等人类活动因子作为比较数列,对草地退化进行了多因素关联分析。研究结果客观、定量地揭示了草地退化与各因素间的相互关系,认为草地生态系统的退化受损是气候变化和人类活动共同胁迫的结果,人类对草地的管理方式对草地生态系统具有巨大影响,人类可以通过多种管理措施来减轻牲畜对草场的压力,积极解决人与资源的平衡。     

鸡病毒性关节炎病毒C-98分离株S1基因的克隆与序列分析

提取鸡病毒性关节炎病毒（AVAV）内蒙古分离株（C-98株）总RNA，参考GenBank中禽呼肠孤病毒（ARV）S1133株S1基因序列设计了2对引物，应用RT—PCR技术扩增了病毒S1基因，将S1基因cDNA克隆到pGEM—T Easy载体后测序。将测定序列拼接后与参考毒株ARV-176、ARV-138、ARV-S1133、MDRV—YJL的S1基因序列进行了比较。结果显示，AVAV C-98分离株的S1基因与强毒株ARV-176株的同源性最高，达99．9％；与MDRV—YJL的同源性为99．3％，与弱毒疫苗株ARV—S1133的同源性也达97．9％；与ARV-138株的同源性最低，为81．2％。表明，AVAVC-98株与参考毒株的差异较小，与疫苗株ARV-S1133有很高的同源性。     

广西10个地方优质品种鸡γ-干扰素基因的克隆与序列分析

根据基因库中鸡γ-干扰素的基因序列设计了1对特异性引物，应用反转录-聚合酶链式反应（RT-PCR）技术，从ConA诱导培养的广西10个地方优质品种鸡外周血淋巴细胞RNA中扩增了γ-干扰素基因，结果，均得到了大小为520 bp的特异性片段。将扩增产物纯化并克隆到pMD18-T载体上，获得重组质粒，经PCR和EcoRⅠ＋SalⅠ双酶切鉴定后测序。序列分析结果表明，广西10个地方优质品种鸡γ-干扰席基因均编码145个氨基酸的成熟蛋白，分子质量约为16．8ku，与哺乳动物和其他品种鸡的核苷酸序列同源性分别为38．8％～39．0％和99．2％～100％，氨基酸序列同源性分别为23．69／6～24．8％和97．6％～99．4％。     

Appraisal of the sustainability of dairy goat systems in Southern Spain according to their degree of intensification

This investigation aims to classify, describe and evaluate the sustainability of dairy goat production systems (GPS) in South Spain Sierra de Cadiz. The research took place throughout 25 goat farms during the 2001–2002 campaigns, with the method posed by Masera et al. (1999) [Masera, O., Astier, M., S., López-Ridaura. 1999. Sustentabilidad y manejo de recursos naturales. El marco de evaluación MESMIS (Sustainability and natural resource management. The MESMIS evaluation framework). Mundi-Prensa, S.A., Gira, IE-UNAM, México. 109 pp.] and adapted to animal production systems, as the guideline and framework to evaluate sustainability.

The principal component, namely energy input from grazing (eigenvalue 1.329) which comprises the indicators total area per goat (factorial value 0.664) together with net energy obtained from grazing (factorial value 0.903) allowed to differentiate significantly between semi extensive (SES), semi intensive (SIS) and intensive (IS) goat production systems.

Intensification of the GPS tends to be inefficient, especially in terms of net margin per litre of milk produced (p < 0.05). A higher degree of adaptability of IS (64.8%) derives from a higher investment on new production strategies. Likewise, higher self-management capacity of SES (60.9%) fosters standards of productivity (76.0%) and stability (42.9%). The SIS presented the highest equity values (67.8%).

On the whole, sustainability of GPS tends to decrease as the degree of intensification increases: SES = 57.3%; SIS = 55.7% and IS = 53.1%. The reduction of the dependency on external input alongside with the optimization of natural resources management would surely improve the standard of sustainability.     

Selection for ovulation rate in rabbits

An experiment of selection for ovulation rate was carried out. Animals were derived from a synthetic line first selected 12 generations for litter size, then 10 generations for uterine capacity. Selection was relaxed for 6 generations. Selection was based on the phenotypic value of ovulation rate with a selection pressure on does of 30%. Males were selected from litters of does with the highest ovulation rate. Males were selected within sire families in order to reduce inbreeding. Ovulation rate was measured in the second gestation by a laparoscopy, 12 days after mating. Each generation had about 80 females and 20 males. Results of three generations of selection were analyzed using Bayesian methods. Marginal posterior distributions of all unknowns were estimated by Gibbs sampling. Heritabilities of ovulation rate (OR), number of implanted embryos (IE), litter size (LS), embryo survival (ES), fetal survival (FS), and prenatal survival (PS) were 0.44, 0.32, 0.11, 0.26, 0.35, and 0.14, respectively. Genetic correlation between OR and LS was 0.56, indicating that selection for ovulation rate can augment litter size. Response to selection for OR was 1.80 ova. Correlated responses in IE and LS were 1.44 and 0.49, respectively. Selection for ovulation rate may be an alternative to improve litter size.     

Longevity of Swiss Brown cattle in different housing systems in Switzerland

A Weibull mixed survival model was used to study the effect of a change in the housing system on length of productive life (LPL) in dairy cows. The data set included records on 71,469 Swiss Brown cows in 1674 farms in eastern and central Switzerland. About 36% of the records were right-censored. The observation period lasted from January 1, 1988 to May 1, 2001. During this period, 517 farms changed their housing conditions from a tie-stall barn to a loose housing system. Besides a random time-dependent effect of herd–year–season, the model included fixed effects of housing system, lactation number and stage of lactation, within herd and parity production level (all time-dependent), and age at first calving (time-independent). All effects had a significant effect on LPL at a level of p < 0.001. Cows in loose housing systems showed the lowest risk ratios of being culled (0.93) compared to the reference system tie-stall barn (1.00). The highest relative culling rate (1.09) was observed within the changing period from tie-stall barn to loose housing system. Within the first three lactations, the relative culling risk increased stepwise with lactation stage. The hazard slightly increased from first until lactation number 8 and higher. The relative culling rates were highest (2.22) for cows yielding less than 90% compared to herd-mates of the same lactation number, whereas the lowest risk ratios were estimated for animals yielding more than 110% compared to their reference group (0.64). When heifers were older than 3 years at first calving, there was a tendency towards a higher relative culling risk (1.06).