In vitro development of IVF-derived bovine embryos following cytoplasmic microinjection for the episomal expression of the IGF2 gene

Important genomic imprinting changes usually occur following the in vitro production (IVP) of bovine embryos, especially in the imprinting pattern of components of the IGF system. This study aimed to evaluate the effects of a transient episomal overexpression of the IGF2 gene in bovine IVP embryos following embryo cytoplasmic microinjection (CMI) at the 1-cell stage on embryo survival, early and late developmental kinetics and morphological quality up to Day 7 of development. Selected cumulus–oocyte complexes (COCs) were matured and fertilized in vitro and subsequently segregated into six experimental groups: non-CMI control group and five CMI groups at increasing doses (0, 10, 20, 40 and 80 ng/μl) of a GFP vector built for the episomal expression of bovine IGF2. Zygote CMI was effective in delivering the expression vector into the ooplasm, irrespective of the groups, with 58% of positive GFP fluorescence in Day 7 blastocysts. Considering developmental rates and late embryo kinetics, the 10-ng/μl CMI vector dose promoted a lower blastocyst rate (10.4%), but for blastocysts at more advanced stages of development (93.0% blastocysts and expanded blastocysts), and higher number of cells (116.0 ± 3.0) than non-CMI controls (23.3%, 75.0% and 75.0 ± 6.8 were obtained, respectively). In conclusion, CMI at the 1-cell stage did not compromise subsequent in vitro development of surviving embryos, with the 10-ng/μl group demonstrating a possible growth-promoting effect of the IGF2 gene on embryo development, from the 1-cell to the blastocyst stage.     

EGF在哺乳动物卵母细胞体外受精中的作用

[目的]为卵母细胞的生长发育创造更加适宜的环境。[方法]对EGF的理化特性、作用机理及其在卵母细胞体外培养、体外受精和早期胚胎发育中的作用进行阐述。[结果]EGF、IGF和TGF等生长因子在哺乳动物卵母细胞体外培养中起很重要的作用,尤其是在无血清培养条件下。生长因子可大大提高卵母细胞的成熟率和受精率,并对受精卵的发育有很大的促进作用。在众多生长因子中研究的最多的就是EGF。EGF能够促进卵母细胞减数分裂、卵丘细胞扩散,调节卵母细胞胞质成熟。[结论]对EGF的深入研究对于提高哺乳动物卵子的体外成熟率、体外受精率以及胎儿的发育都具有重大意义,为体外受精等技术和胚胎工程的发展提高可靠的保障。但对清楚了解EGF及其受体的性质和作用机制仍存在很多问题,且对表皮生长因子对体外受精的作用研究较少。     

GMP玻璃化冷冻对水牛MⅡ期卵母细胞冷冻损伤和体外发育能力的影响

将体外成熟(IVM)24h的水牛卵母细胞随机分成对照组、冷冻剂毒性试验组、GMP玻璃化冷冻组,研究玻璃微细管法(GMP)冷冻对水牛MⅡ期卵母细胞冷冻损伤和体外受精后发育能力的影响。结果表明:冷冻剂毒性试验组的存活率显著高于GMP玻璃化冷冻组;在透明带消化时间上,冷冻剂毒性试验组和GMP玻璃化冷冻组显著高于对照组。在单精入卵率上,冷冻剂毒性试验组和GMP玻璃化冷冻组显著低于对照组;在无精子入卵率上,冷冻剂毒性试验组和GMP玻璃化冷冻组与对照组差异显著;而多精入卵率3组间差异不显著。卵母细胞冷冻后进行体外受精,3组之间的2-细胞率,8-细胞率和桑椹胚率差异均极显著。表明冷冻剂和GMP玻璃化冷冻均会引起水牛MⅡ期卵母细胞透明带硬化,降低精子穿透率和其体外受精的发育能力。     

两种不同方法处理牛分离精子对体外受精效果的影响

本试验旨在探讨采用2种不同方法处理牛分离精子对精子活力、浓度及体外受精（IVF）效果的影响。将体外培养成熟卵母细胞随机分为2组,与分别用洗涤法和Percoll法处理牛分离精子进行IVF,并观察处理后各组的精子活率、浓度和IVF后囊胚发育率。结果显示,洗涤法和Percoll法处理后精子活力和IVF后的囊胚发育率均无显著差异,但采用洗涤法处理后分离精子浓度极显著高于Percoll法,可显著提高分离精子利用效率,且方法简便、经济,应优先选择使用。     

泛素蛋白酶体途径及其在体外受精中的作用研究进展

泛素蛋白酶体途径（ubiquitin proteasome pathway,UPP）是生物体内最主要的蛋白质降解途径,与多种疾病有关,在生物体内具有十分重要的作用,主要降解错误折叠的、多余的蛋白质。UPP是一个循环途径,其主要作用起始于泛素（ubiquitin,Ub）的激活,是受泛素激活酶（ubiquitin-activating enzyme,E1,酵母菌中是UbE1）、泛素结合酶（ubiquitin-conjugating enzyme,E2,UbE2）、泛素连接酶（ubiquitin-protein ligase,E3,UbE3）和去泛素化酶（deubiquitinating enzymes,DUBs）调控的级联过程,最终使被多聚泛素化（polyubiquitination,polyubiquitination,Poly-Ub）标记的蛋白底物在UPP的蛋白水解核心--26S蛋白酶体内被降解成寡肽,寡肽可以进入新的蛋白循环,Ub则由DUBs去除进入下一个UPP循环。UPP在海鞘类和一些哺乳类体外受精（in vitro fertilization,IVF）过程中具有十分重要的作用,能够参与精子获能和顶体反应（acrosomal reaction,AR）,促进精子顶体胞吐,在精卵结合时降解透明带（zona pellucida,ZP）蛋白,辅助精子穿透卵母细胞ZP,促进精子与卵母细胞ZP的融合,从而促使IVF的成功。通过在IVF液中添加一些UPP相关的抗体或抑制剂能够抑制IVF过程中的多精入卵,提高IVF率。作者综述了UPP的主要组成成分及其对IVF的辅助作用及相关抗体的研究进展,以期为今后研究UPP循环在生物体内的作用机制、与生物体内各种疾病的关系、在IVF过程中的作用机制及抑制多精入卵等提供一定的理论依据。     

Molecular cloning and expression of FGF2 gene in pre‐implantation developmental stages of in vitro‐produced sheep embryos

Early embryonic mortality is one of the main sources of reproductive loss in domestic ruminants including sheep. Fibroblast growth factor‐2 (FGF‐2) is a member of FGFs family that mediates trophoblast activities and regulates embryonic development in various species. In this study, we have cloned, characterized sheep FGF2 cDNA (KU316368) and studied the expression in sheep embryos. Ovaries of non‐pregnant sheep were collected from local abattoir and matured in culture medium at 38.5ºC, 5% CO₂, 95% humidity for 22–24 hr. The matured oocytes were inseminated with capacitated spermatozoa in Brackett and Oliphant medium and resulted embryos were cultured in CO₂ incubator for 6–7 days to complete the developmental stages from two cells to blastocyst stage. Total RNA was extracted from immature oocytes (n = 100), mature oocytes (n = 100) and different stages of embryos such as 2 cell (n = 50), 4 cell (n = 25), 8 cell (n = 12), 16 cell (n = 6), morula (n = 5) and blastocyst (n = 3). The total RNA isolated from the oocytes and embryos was reverse transcribed and subjected to real‐time polymerase chain reaction using sequence‐specific primers and SYBR green as the DNA dye. On sequence analysis, the nucleotide sequence of sheep FGF2 exhibited highest sequence similarity with cattle (100%) and least with rat and mouse (69.2%). At the deduced amino acid level, a highest degree of similarity was noticed with cattle, buffalo, goat, pig, camel and horse (100%) and lowest degree of identity with rat, human and mouse (98.2%). The FGF2 mRNA expression was higher in immature and mature oocytes and gradually decreases from 2‐cell stage of embryo to the blastocyst stage. More over a significant differences in FGF2 mRNA expression (p < .05) were observed between immature oocytes and all pre‐implantation stages of embryo. It can be concluded that FGF‐2 plays a significant role in pre‐implantation and early development of embryos in sheep.     

精浆对猪精子冷冻效果影响的研究

为优化猪精子冷冻技术,提高解冻后精子的活力和受精能力,本试验分别以含精浆浓度为10%、20%和30%的冷冻保护剂处理精子,以冷冻前、解冻后精子活力和质膜完整性,解冻后精子进行体外受精(IVF)的卵裂率和囊胚率等作为检测指标,同时以含有卵黄的Tris-柠檬酸－葡萄糖(Tris-citric acid-glucose,TCG)冷冻基础液作为对照研究精浆对猪冷冻精子的保护作用。结果显示,在含有10%精浆浓度的稀释液中,冷冻前质膜完整性,解冻后精子活率、质膜完整性、IVF囊胚率相对于对照组均显著提高(P<0.05);当含有10%精浆的冷冻精液解冻后用于人工授精时,与配母猪妊娠率、窝产仔数、窝产活仔数等仍显著低于鲜精授精组(P<0.05)。上述结果表明,含10%精浆的冷冻保护剂能提高精子的冷冻后活力和IVF胚胎发育率,但用于人工授精配种与鲜精相比还有一定差距。     

Ghrelin对水牛体外受精和孤雌激活胚胎体外发育的影响

本研究的目的是探讨Ghrelin对水牛体外受精和孤雌激活胚胎体外发育的影响.体外成熟的水牛卵母细胞经体外受精或离子霉素孤雌激活后.分别在舍0,0.5,5,50和500 μg/L Ghrelin的培养液中进行体外培养,观察各组胚胎的卵裂率和囊胚率.结果显示,在培养液中添加不同浓度的Ghrelin对体外受精和孤雌激活胚胎的卵裂率均无显著影响(P>0.05),但添加500 μg/L的Ghrelin显著提高体外受精胚胎的囊胚发育率(33.5% vs 13.7%,P<0.05),50 μg/L或500 μg/L的Ghrelin均显著提高孤雌激活胚胎的囊胚发育率(32.4%和34.6% vs 14.5%,P<0.05).结果表明,培养液中添加Ghrelin对胚胎的早期卵裂没有影响,但可促进水牛体外受精和孤雌激活胚胎囊胚的形成.     

组织蛋白酶抑制剂E-64对猪卵母细胞体外发育能力的影响

为探明外源性组织蛋白酶抑制剂(E-64)对猪卵母细胞体外发育能力的影响,通过向成熟液中添加1、5、10μmol/L的外源性组织蛋白酶抑制剂,对猪卵丘-卵母细胞复合体(COCs)进行体外成熟培养46 h,统计第一极体率,随后分别进行体外受精和孤雌激活,统计第2天的卵裂率和第7天的囊胚率。结果表明,成熟液中加入1μmol/L E-64的第一极体排出率显著高于未添加的对照组以及5、10μmol/L E-64的添加组。将体外成熟的卵母细胞进行体外受精及孤雌激活,体外受精后胚胎的卵裂率与囊胚率结果均为成熟液中加入1μmol/L E-64的添加组显著高于对照组以及5、10μmol/L E-64的添加组;孤雌激活后,4组间胚胎的卵裂率差异不显著,囊胚率为10μmol/L E-64的添加组显著低于其他3组。因此1μmol/L E-64能促进猪卵母细胞的核成熟,并能进一步提高其体外受精后的卵裂率和体外培养的囊胚率。     

不同氧气浓度对绵羊体外受精胚胎凋亡相关基因表达的影响

[目的]研究绵羊胚胎体外发育过程中细胞凋亡的机制,以进一步提高胚胎体外发育能力。[方法]利用Real-time PCR技术,分别检测凋亡相关基因Mcl-1、Bad、Bak、Bik和Caspase-3在低氧环境(5%O2)和高氧环境(20%O2)培养的绵羊体外受精(IVF)胚胎中的表达水平。[结果]不论是高氧环境还是低氧环境,从2-细胞阶段到囊胚期均可检测到Mcl-1、Bad、Bak、Bik和Caspase-3的表达,Caspase-3基因表达水平随着胚胎的发育有逐渐增高的趋势,且高氧和低氧间差异不显著(P0.05);从8-16细胞期开始,Mcl-1、Bad、Bak和Bik表达水平都显著增加,且低氧环境中的表达水平均明显低于高氧环境中的表达水平(P0.05)。[结论]氧气浓度在一定程度上影响了绵羊胚胎中凋亡相关基因的表达,绵羊胚胎细胞凋亡可能是凋亡相关基因Mcl-1、Bad、Bak、Bik和Caspase-3相互协同的结果。