牛体外胚胎生产技术的影响因素

体外胚胎生产技术对于家畜的繁殖潜力挖掘、快速扩繁以及种质资源保护具有重要的价值。自上世纪80年代起,科研人员围绕牛体外胚胎生产开展了广泛而深入的研究,并取得了良好的进展。目前牛胚胎体外生产的基本体系已经确立,在体外培养条件下能够稳定的获得囊胚,但是在牛胚胎体外生产过程中仍然有许多因素和机制没有被彻底阐释,从而限制着牛胚胎体外生产水平。本文综述了牛卵母细胞体外成熟、体外受精及早期胚胎体外培养的相关技术环节的研究进展,并对包括培养液的添加物质、培养过程中的氧化应激等相关影响因素进行了探讨,以期为进一步提高牛胚胎体外生产水平提供依据。     

葡萄糖在牛体外受精及胚胎发育中的影响

在牛精子获能液中添加不同浓度的葡萄糖,应用体外培养技术对牛精子体外获能及早期胚胎发育进行研究,通过观察顶体反应、超激活、活率和早期胚胎发育率,筛选出获能液中最适葡萄糖浓度及其有利于牛早期胚胎发育的最佳浓度.结果表明:葡萄糖是精子获能和维持超激活运动的主要能源物质,其代谢过程中产生的活性氧在牛精子体外获能、受精过程中起重要作用,高浓度(超过9.15 mM)葡萄糖有利于获能的完成;但是对早期胚胎发育不利,对早期胚胎发育来说其最适添加量为6.10 mM,此时的囊胚率最高.     

抗氧化剂对家畜胚胎体外发育影响的研究进展

现在研究普遍认为活性氧自由基是导致胚胎体外发育阻滞的主要原因。本文主要综述了不同抗氧化剂对牛胚胎体外发育的影响,并分析其作用机制。     

褪黑素对卵母细胞成熟和胚胎体外发育影响的研究进展

卵母细胞与胚胎体外培养过程中,细胞处于相对高氧环境,常常会由于抗氧化防御不足而导致氧化应激,使细胞在发育过程中积累大量的活性氧(ROS),从而降低卵母细胞及胚胎的体外发育率。褪黑素作为一种有效的抗氧化剂和自由基清除剂,能显著降低细胞内ROS水平,清除细胞内自由基,改善卵母细胞的体外成熟与胚胎的体外发育历程。本文从褪黑素对卵母细胞成熟、胚胎体外发育、胚胎质量以及褪黑素作用机制等方面进行综述,为褪黑素在体外胚胎生产中的应用提供参考。     

半胱氨酸对猪卵母细胞体外成熟、体外受精及GSH水平的影响

体外受精技术也称胚胎生产技术（invitro production,IVP）,包括卵母细胞的体外成熟、精子的获能、卵子的体外受精和受精卵的体外培养等几个连续的过程。半胱氨酸是GSH的前体物质,在牛体外胚胎生产过程中疏基复合物能增加细胞内GSH的合成,在受精和胚胎的开始阶段保持高浓度GSH可以增加发育率。试验的目的是评价半胱氨酸对猪卵母细胞的成熟率、受精率及成熟培养时期卵母细胞内GSH水平的影响,现报道如下。     

牛胚胎体外生产质量控制

牛胚胎体外生产质量控制就是在常规实验的基础上 ,避免额外因素对胚胎体外生产造成影响。本文从实验记录、卵母细胞、精液、培养条件、胚胎质量等方面分析讨论了牛胚胎体外生产中的质量控制     

牛体外生产囊胚染色体异常的分析

有研究发现,体外生产的胚胎染色体异常的发生率高于体内胚胎。Viuff等人在一项对牛体外胚胎染色体异常的研究中发现,体外生产的牛囊胚的混倍率为72%,而体内生产的囊胚混倍率仅为25%。这说明,胚胎生产的操作过程、培养液成分和其他的一些环境因素可能是引起胚胎发生染色体异常的     

牛体外胚胎冷冻保存的研究进展

体外胚胎冷冻保存技术是胚胎移植技术的重要组成部分,在辅助生殖技术中发挥重要作用,同时对种质资源保存、加强遗传改良和促进优质种源国际交流等方面具有重要意义。然而,体外胚胎冷冻过程中存在脂质含量过高、活性氧水平升高及机械损伤等问题,导致体外胚胎冷冻效率低,这极大地限制了体外胚胎冷冻保存技术的广泛应用。大量研究表明,通过去脂质、优化体外胚胎培养液、人工塌陷囊胚腔和优化冷冻程序等手段,可以有效提高冷冻后胚胎的存活率和发育能力。因此,本文概述了体外胚胎冷冻保存技术的研究进展和胚胎冷冻过程中存在的问题,总结了提高体外胚胎冷冻效率的方法措施,旨在为提高体外胚胎冷冻保存效率提供一定参考。     

体外卵母细胞的抗氧化作用研究进展

卵母细胞体外成熟培养是体外生产胚胎的关键步骤之一,在人工辅助生殖技术及胚胎工程中起着不可替代的作用。随着国内外对哺乳动物体外受精及胚胎体外发育研究的日益深入,这一动物生物技术也开始备受关注。研究发现,卵裂率及囊胚发育率与卵母细胞成熟水平呈正向相关,而活性氧(reactive oxygen species,ROS)是影响卵母细胞成熟水平的主要原因之一。在离体培养卵母细胞过程中,过高水平的活性氧能够引起氧化应激,破坏细胞结构,导致细胞功能失调,不利于卵母细胞维持正常生殖功能。文章对卵母细胞体外培养过程中抗氧化机制的研究进展进行了综述。     

活性氧对哺乳动物早期胚胎体外发育阻滞的研究进展

哺乳动物早期胚胎体外培养过程中常发生体外发育阻滞现象，活性氧是引起发育阻滞的重要原因之一，作者综合国内外研究报道，综述了活性氧对哺乳动物早期胚胎体外发育的影响及克服发育阻滞现象的方法，为哺乳动物胚胎体外培养提供一些参考。     

Scrapie in goats in Cyprus

Ovine scrapie was first recorded in Cyprus in 1985. Subsequently four dairy goats kept in two mixed flocks with affected sheep developed characteristic clinical signs similar to those seen in sheep. Fifteen goats from the two flocks were examined histologically and neurological lesions consistent with a diagnosis of scrapie were found in the four animals and in three others which had subsequently developed early neurological signs. These lesions were similar to those of naturally-affected sheep although neuronal degeneration and vacuolation were more severe in some cases.     

Heartworm in dogs in Canada in 1984

In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.

Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.

     

Heartworm in dogs in Canada in 1991

In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium.     

Heartworm in dogs in Canada in 1983

In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.

Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.

     

Heartworm in dogs in Canada in 1985

In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).

Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).     

Heartworm in dogs in Canada in 1989

In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.

Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.