马COMT基因第4外显子多态性分析

探讨COMT基因第4外显子(C4位点)多态性,进而探究不同品种马在该位点的遗传变异程度和选育强度。采用PCR-SSCP方法对不同品种马的COMT基因C4位点进行多态性分析。结果表明:第4外显子区域存在多态现象,发现AA、BB 2种基因型,并有3处突变分别是13处C突变为A、199处C突变为G的颠换、120处T突变为C的转换。不同品种间的基因型分布存在差异,纯血马的优势基因型和优势等位基因是BB型和B;而乌审马、锡尼河马、三河马、巴尔虎马、乌珠穆沁马的优势基因型和优势等位基因均为AA型和A;处于哈代-温伯格平衡状态(P0.05)的只有巴尔虎马,其他品种马都没有处于哈代-温伯格平衡状态(P0.01)。纯血马C4位点的杂合度为0.499,多态信息含量为0.374,呈中度多态性。纯血马C4位点杂合度和多态信息含量较高,表明该群体的遗传物质基础一致性较高,该位点遗传性能趋于稳定。     

马生长激素(GH)基因的PCR-SSCP研究

选取4个蒙古马地方品种、1个国内培育品种和1个国外引人品种共281匹马，采用PCR—SSCP技术，检测了GH基因5’侧翼区、第1内含子、第2外显子和第5外显子4个位点的遗传多态性。结果显示：仅第5外显子出现多态性，表现出AA、BB和AB3种基因型，其余位点未检测到多态。群体遗传学分析结果表明：除纯血马外，其余品种都是等位基因A为优势基因；Hardy-Weinberg平衡检验显示，乌审马、乌珠穆沁马、巴尔虎马处于平衡状态，锡尼河马、三河马、纯血马处于非平衡状态；各品种马的多态信息含量均为中度多态（0．25〈PIC〈0．5）。本研究为今后马的分子育种奠定一定基础。     

西南矮马矮小性状基因SHOX的克隆测序和多态性研究

本研究首次克隆出西南马矮小性状基因完整第二外显子序列,GenBank登录号为EU556739;通过PCR-SSCP方法对8个品种150匹马的该序列做了多态性分析,在P2位点上268处有1个G→A的突变,和431处有1个T→G的突变导致了等位基因B变为等位基因A.该位点除云南文山马(WS)的优势基因型和优势等位基因分别为AB型和B外,其余类群马均为BB型和B.云南丘北马(QB)、云南文山马(WS)、云南大理马(DL)、建昌马(JC)和设特兰马(ST)在P2位点上处于Hardy-Weinberg平衡状态.     

欧拉型藏羊GH基因部分序列PCR-SSCP分析

采用PCR-SSCP方法,检测126只欧拉型藏羊GH基因第1、2内含子、第1～4外显子序列的遗传多态性,结果表明:仅第4外显子出现多态性,存在2个等位基因3种基因型(AA、AB和BB),BB基因型频率最高,B等位基因频率明显高于A等位基因频率,其余位点未检测到多态.群体遗传学分析结果表明:该群体在这一位点上处于Hardy-Weinberg平衡状态(P＞0.05),多态信息含量(PIC)为0.231 3,为低度多态(PIC＜0.25).测序结果显示:与藏绵羊GH基因序列(EFU77162)相比,B等位基因在1 286bp处发生T→C的突变,该突变为同义突变.     

欧拉型藏羊CAPN1基因部分序列多态性检测

利用PCR-SSCP方法,设计两对引物(L1、L3)对134只欧拉型藏羊CAPN1基因部分序列进行多态性检测.检测结果分析表明L1引物存在从、AB和BB 3种基因型.不同基因型PCR产物测序结果分析发现在第5内含子和第6外显子上各存在1个单核苷酸多态位点,分别是扩增序列190 bp处的A→G的突变和扩增序列260 bp处的A→G的突变,但外显子的突变为同义突变.L3引物PCR-SSCP检测未发现多态位点.群体遗传学分析表明:该群体在突变位点的多态信息含量为0.345 2,属中度多态,X2检验表明该群体处于Hardy-Weinberg平衡状态(P＞0.05).     

猪2,4-双烯-辅酶A还原酶（DECR1）基因的多态性研究

选取山西马身猪、山西白猪、长白猪、大白猪和杜洛克猪5个品种共454头,采用PCR-SSCP技术,检测了DECR1基因第5外显子位点的遗传多态性.结果显示,DECR1基因第5外显子位点存在多态性,表现出CC、CD、DD三种不同基因型.群体遗传学分析结果表明,除山西马身猪外,其余品种都是等位基因D为优势基因;Hardy-Weinberg平衡检验显示,长白猪、大白猪、山西白猪处于平衡状态,山西马身猪、杜洛克处于非平衡状态;各品种猪的多态信息含量均表现为中度多态,PIC值均在0.3629～0.3748之间.     

秦川牛IRS-1基因多态性与体尺和肉质性状的相关性

旨在研究秦川牛IRS-1基因外显子的多态性,及其与秦川牛体尺和肉质性状的相关性。选取384头同等饲养条件下的18～24月龄健康秦川牛母牛为研究对象,采用PCR-SSCP技术结合DNA测序技术检测IRS-1基因外显子上存在的SNPs位点,并将其与秦川牛体尺和肉质性状进行关联分析。经DNA测序发现,在IRS-1基因外显子的2 346(B1位点)和2 394bp处(B2位点)分别发生了G→A和C→G突变,经分析发现,分别为氨基酸序列第782处Glu和798处Leu的同义突变。通过SSCP带型分析分别出现CC、CD和AA、AB 2种基因型,均未检测出第3种纯合基因型;卡方检验显示,B1位点在所检测牛群中处于Hardy-Weinberg平衡状态(P>0.05),而B2位点则处于Hardy-Weinberg极度不平衡状态(P<0.01);且B1处CC基因型为优势基因型,C为优势等位基因,处于低度多态状态;B2处基因型AA为优势基因型,A为优势等位基因,处于低度多态状态;关联分析表明,B1位点不同基因型个体间在体斜长、腰角宽、胸围和眼肌面积方面差异显著(P<0.05),B2位点在腰角宽、胸深和背膘厚方面差异显著(P<0.05)。将2个突变位点合并基因型进行单倍型分析发现,双杂合基因型个体(ABCD)除背膘厚和肌间脂肪含量外其他所分析的各性状均显著高于其他基因型组合,且多标记位点的组合效应值高于单标记位点。结果提示,IRS-1基因对秦川牛体尺及部分肉质性状有显著的影响,可以作为秦川肉牛新品系培育早期选择的候选基因,其中组合ABCD可能是影响秦川牛体尺和胴体性状的最佳基因型组合。     

5个猪种DECR1基因外显子2单链构象多态性的群体遗传学分析

试验利用PCR-SSCP技术检测了山西马身猪、山西白猪、长白猪、大白猪和杜洛克猪5个品种共490头猪的DE-CR1基因外显子2的多态性。结果显示,DECR1基因外显子2位点存在多态性,表现出AA、BB和AB 3种基因型。群体遗传学分析结果表明,5个猪种都是等位基因B为优势基因;Hardy-Weinberg平衡检验结果显示,山西白猪和杜洛克猪处于平衡状态,山西马身猪、长白猪和大白猪处于非平衡状态;各品种猪的多态信息含量均为中度多态。     

合作猪γ-IFN基因外显子4多态性分析

为了研究合作猪γ-IFN基因的多态性,确定其等位基因数、核苷酸多态位点,各等位基因是否符合Hardy-Weinberg平衡状态、多态信息含量、有效等位基因数和杂合度,采用PCR-SSCP方法检测了138头合作猪γ-IFN基因外显子4的等位基因,并克隆、测序群体内变异产生的各等位基因序列,就基因型和等位基因单倍型序列数据开展分析。序列比对分析发现5个核苷酸多态位点,其中5 284 bp(A→G)、5 341 bp(G→A)、5 371 bp(A→G)为新发现突变位点。试验群体发现4种基因型AA、AB、AC和AD,其中A等位基因频率为0.963 8,为优势等位基因。经χ2适合性检验,该群体处于Hardy-Weinberg平衡状态(P>0.05)。γ-IFN基因遗传多态指数中,杂合度(He)、多态信息含量(PIC)、有效等位基因数(Ne)均较低,表明合作猪γ-IFN基因比较保守。     

高原型藏绵羊KAP基因单核苷酸多态性分析

试验旨在寻找角蛋白辅助蛋白(keratin-associated proteins,KAP)基因与产毛性状相关的多态位点,为藏绵羊产毛性状的分子标记提供理论依据。采用PCR-SSCP技术对高原型藏绵羊角蛋白辅助蛋白基因家族中KAP3.2、KAP7基因部分序列和KAP8基因外显子进行多态性分析。结果表明,3个基因座都存在多态性,均检测到AA、AB和BB 3种基因型。KAP3.2基因以A等位基因为优势等位基因,AA基因型为优势等位基因型;KAP7和KAP8基因均以B等位基因为优势等位基因,BB基因型为优势等位基因型。高原型藏绵羊在KAP3.2和KAP8基因座达中度多态,而在KAP7基因座为低度多态,在KAP3.2和KAP8位点上基因型频率处于Hardy-Weinberg非平衡状态。测序分析结果表明,KAP3.2和KAP8基因上分别存在1个C→T(271 bp)和1个T→C(1122 bp)的突变,均属于同义突变,KAP7基因5′调控区存在1个T→C(102 bp)的突变。     

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.