草原红牛生长激素基因遗传多态性研究

为寻找可用于标记辅助选择的分子标记，研究以草原红牛为试验群体，采用单链构象多态性（PCR—SSCP）方法检测了GH基因遗传多态性，并对GH基因多态片段进行了克隆、测序，确定了多态位点的变异位置和碱基类型。检测结果表明：在GH基因5’末端、第3内含子、第4内含子、外显子5和3’末端存在多态性位点，其中在5’上游431处有一个A→G碱基的突变，在1435处发生了T→C的突变，第4内含子1918处发生了C→A的突变；外显子5的2291处发生了碱基A→C突变；3’末端2639处发生了碱基C→G突变，并导致一个HaeⅢ酶切位点的增加；同时与GenBank中序列（accession numberM57764）相比较，草原红牛在1692处有C→T的突变，在2735处有碱基T→C突变，这些突变位点为草原红牛所特有。     

中国地方黄牛GH基因遗传多态性研究

以鲁西牛、南阳牛为试验动物，利用PCR-SSCP和PCR-RFLP技术研究了以上2个地方黄牛品种生长激素（GH）基因第3内含子、第4内含子、第5外显子、3’端和5’端位点的遗传多态性。检测结果表明：GH基因第3内含子1547bp处发生碱基C→T的替换；GH基因第4内含子位点多态的产生是由于1947bp处发生碱基T→G的替换；GH基因第5外显子2141bp处碱基C→G的突变，使得亮氨酸变成缬氨酸，造成氨基酸发生变化。GH基因3’端的PCR-RFLP结果表明：由于2639bp处碱基GCC→GGC的突变造成HaeⅢ酶增加1个酶切位点；GH基因5’端位点多态的产生是由303bp处碱基C→T的突变造成。     

两个黄鸡品种E-FABP基因第三内含子的多态性分析

本研究通过PCR扩增对141羽京海黄鸡和30羽苏禽黄鸡E-FABP基因第三内含子的多态性进行了研究。在京海黄鸡发现了AA、AB、AC、BC、CC五种基因型,在苏禽黄鸡中检测到了除BC型以外的四种基因型。在两个鸡品种中A和C等位基因的频率明显高于B等位基因频率,对两个纯合基因型测序分析表明:在鸡E-FABP基因的第三内含子4269~4288bp处有20个碱基缺失,并在4273bp处发生了A→C的突变。     

早胜牛CD36基因多态性分析

为研究CD36基因在早胜牛群体中的遗传变异及其与肉质性状的关联性,本试验采用DNA混合池测序技术检测了320个样本的SNPs位点,并估算了SNPs位点的等位基因频率。结果表明,外显子区域有2个多态位点,分别是外显子8的79201bp处A缺失和外显子12的86351bp处T→A突变。内含子区域有3个多态位点,分别是内含子8的79309bp处C→A突变和内含子12的86446bp处C→A突变、86447bp处G→A突变,其余区域未检测到碱基突变。外显子8的A缺失可能引起氨基酸序列发生改变。外显子12的T→A突变属同义突变,未引起氨基酸改变。后续我们将对CD36基因多态性与早胜牛肉质性能相关性进行分析,以期寻找到与肉质性能关联的SNPs位点,为研究提高早胜牛肉质性能的工作提供参考。     

牛类胰岛素生长因子IGF-I基因研究

采用PCR-SSCP和PCR-RFLP技术分析了类胰岛素生长因子1（IGF-I）基因5’侧翼区、第5外显子、第2外显子在南阳牛、鲁西牛、中国西门塔尔牛3个牛品种中的遗传多态。结果表明在IGF-I基因的5’侧翼区、第5外显子上未发现PCR-SSCP或PCR-RFLP遗传多态；在第2外显子中发现PCR-SSCP多态，有3种基因型AA型、AB型、BB型。对第2外显子的多态片段测序分析表明；在35bp处有碱基A→G的突变，248bp处有碱基C→T的突变，256bp处有碱基A→G的突变；35bp、248bp的碱基突变都是无义突变，而256bp处碱基A→G的突变为有义突变，使谷氨酸变为甘氨酸。     

五指山猪FSHβ基因克隆测序及生物信息学分析

为了克隆五指山猪的促卵泡素(follicle-stimulating hormone,FSHβ)基因,获得该基因序列并分析基因结构和相关遗传变异,试验采用PCR扩增FSHβ基因组序列,通过克隆测序寻找基因中的突变位点,采用PCR产物直接电泳法检测FSHβ基因位点的多态性。结果表明:在猪FSHβ基因组中共发现6处单碱基突变位点,分别位于第1内含子(A-757G、A-645G、A-531G)和第2内含子(C+1 431T、A+1 434G、C+1 502T);多态性分析发现,在五指山猪中存在AA和AB两种基因型,其中A等位基因频率为0.96,B等位基因频率为0.04。     

浦东白猪Nramp1基因第6内含子独特突变位点分析

Nramp1是学术界近年研究的猪重要抗病基因之一,其第6内含子作为Nramp1的分型重点片段,国内外的诸多猪种均有清晰的测序分析结果。本研究通过提取浦东白猪血液组织DNA,使用PCR技术分离和克隆Nramp1基因的第6内含子基因片段,测序后与以往文献中的其他猪种进行比较。结果发现,浦东白猪在该段基因中有3个特异的突变点普遍存在,分别是259 bp的A→G突变,331 bp的G→A突变和29 bp后1~2个T碱基的插入。这些突变的发现可以为浦东白猪的育种和Nramp1的抗病性研究提供遗传数据。     

7个猪种MyoD基因家族中3个基因外显子的SNPs检测分析

本研究利用PCR SSCP技术,以7个猪种为研究对象,根据GenBank上猪的MyoG、MyoD和Myf5基因序列设计了17对引物,对此三基因的外显子进行了SNPs检测。检测结果:MyoG和MyoD两个基因均未检测到多态;在Myf5基因的3个外显子上都检测到了多态:第1外显子上有1个点突变G→C;第2外显子上有3个点突变C→A、A→G、G→A;第3外显子上,3387bp处有1个碱基A缺失,3417bp处有3个碱基T缺失,3443bp处有1个点突变T→C。Myf5基因的高度多态性,说明7个猪种含有丰富的遗传变异信息,具有很高的选择潜力。     

6个品种猪Cstb基因的PCR—RELP分析

Cstb基因在人类中已经得到全序列，共5873bp，含有3个外显子、2个内含子，3个外显子的长度分别为66，102，129bp。在猪上的研究还不是很全面，只测得了第2内含子和第3外显子，有待于更深入的研究。在猪Cstb基因第3外显子区内第19个碱基处，检测TapI多态性位点，突变为G→A，是一个错意突变，导致天冬氨酸→天冬酰胺。     

民猪HB-EGF基因第4内含子的克隆与分析

为了研究民猪肝素结合EGF样生长因子(heparin-binding EGF-like growth factor,HB-EGF)第4内含子的序列及其突变位点,试验采用PCR鉴定及基因克隆测序的方法对民猪HB-EGF基因第4内含子序列进行克隆与分析。结果表明:在民猪的HB-EGF基因第4内含子序列中共发现3个点突变,即第27个碱基处插入1个T,78A→78G,101T→101C;第27个碱基处插入的T造成了NlaⅢ酶切位点的改变。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.