猪胚胎冷冻保存研究进展

胚胎冷冻保存技术在大多数哺乳动物上已获得成功,牛胚胎冷冻已经进入商业化应用阶段。猪胚胎由于其特殊的低温生物学特性,冷冻保存研究进展缓慢。本文综述了猪胚胎在冷冻过程中的细胞生物学变化,以及近几年猪胚胎冷冻保存研究所取得的显著进展。     

3种因素对牛卵母细胞玻璃毛细管玻璃化冷冻效果的影响研究

室温下 ,采用GMP(glassmicropipette)玻璃化法对牛卵母细胞进行冷冻保存。结果表明 :不同发育阶段的牛卵母细胞GMP冷冻、解冻后体外受精卵裂率在 36 .6 7%～ 52 .38%之间 ,其中体外培养 2 2h牛卵母细胞的受精卵裂率最高 ,为 52 .38%,与对照组 (6 8.42 %)差异不显著 (P >0 .0 5) ;采用不同的预处理溶液处理冻前牛GV期卵母细胞 ,其中以 3%的EG稀溶液预处理可获得最高的体外受精卵裂率。结果表明 :牛体外成熟卵母细胞冷冻效果最好 ,采用3%EG稀溶液处理玻璃化前卵母细胞可以提高冷冻效果。     

聚乙烯醇在大樱桃砧木吉塞拉组织培养中的作用

以樱桃砧木吉塞拉为试材,研究了不同质量浓度聚乙烯醇(PVA)对樱桃砧木吉塞拉组织培养不同阶段的影响。结果表明,1 g/L的聚乙烯醇可有效提高吉塞拉丛生芽的诱导率,2 g/L的聚乙烯醇不但可以降低其玻璃化率、提高其分化数量,还可以提高其移栽成活率。因此,聚乙烯醇在吉塞拉砧木的初代诱导、继代增殖和生根培养中均有良好的促进作用。     

卵巢玻璃化冷冻保存研究进展

卵巢玻璃化冷冻是一种操作简单、冷冻效果好的卵巢组织冷冻降温技术,对动物繁殖能力保存、物种保护、生物多样性保存,以及动物胚胎工程和人类临床医学研究与应用等具有重要意义。卵巢组织冷冻保存较卵母细胞冷冻保存,具有明显的优点。在冷冻保护剂的选择、冷冻材料、冷冻平衡及冷冻方法上都有其特殊之处。卵巢组织冷冻保存技术已在人类医学临床上发挥其应用价值。     

Generation of rats from vitrified oocytes with surrounding cumulus cells via in vitro fertilization with cryopreserved sperm

The objective of this study was to evaluate fertility and full‐term development of rat vitrified oocytes after in vitro fertilization (IVF) with cryopreserved sperm. Oocytes with or without surrounding cumulus cells were vitrified with 30% ethylene glycol + 0.5 mol/L sucrose + 20% fetal calf serum by using the Cryotop method. The warmed oocytes were co‐cultured with sperm. Although the denuded/vitrified oocytes were not fertilized, some of the oocytes vitrified with cumulus cells were fertilized (32.7%) after IVF with fresh sperm. When IVF was performed with cryopreserved sperm, vitrified or fresh oocytes with cumulus cells were fertilized (62.9% or 41.1%, respectively). In addition, to confirm the full‐term development of the vitrified oocytes with surrounding cumulus cells after IVF with cryopreserved sperm, 108 vitrified oocytes with two pronuclei (2PN) were transferred into eight pseudopregnant females, and eight pups were obtained from three recipients. The present work demonstrates that vitrified rat oocytes surrounded by cumulus cells can be fertilized in vitro with cryopreserved sperm, and that 2PN embryos derived from cryopreserved gametes can develop to term. To our knowledge, this is the first report of successful generation of rat offspring derived from vitrified oocytes that were fertilized in vitro with cryopreserved sperm.     

Comparison of the effects of Ham'sF10 and αMEM in combination with FBS or BSA in vitrification/warming solution on quality and viability of sheep ovarian follicles

The aim of this study was to evaluate the effects of the two types of media, namely minimum essential medium (αMEM) and Ham'sF10, supplemented with foetal bovine serum (FBS) or bovine serum albumin (BSA) in vitrification/warming solution on the quality and viability of sheep ovarian follicles. Vitrification method was applied for cryopreservation of sheep ovarian cortex using Ham'sF10 and αMEM supplemented with either BSA or FBS. There were five groups: Fresh, Ham'sF10+ BSA, Ham'sF10+ FBS, αMEM + BSA and αMEM + FBS. Samples were cultured for two weeks after warming. Viability and morphology of follicles and DNA fragmentation in follicles and in tissue stroma cells were analysed before vitrification/warming and following one and two weeks of culture. The Ham'sF10+ FBS and Ham'sF10+ BSA groups showed a significant decrease in follicular viability after one week of culture (p < .05 vs. Fresh). Following two weeks of culture, all groups revealed a considerable fall in the number of viable follicles (p < .05 vs. Fresh). There was an increase in DNA fragmentation of connective tissue cells but not in the follicles (p < .05). Our results showed the better application of αMEM supplemented with BSA as a vitrification solution in improvement of cryopreservation effects and maintenance of follicular survival.     

西葫芦大孢子离体培养再生植株技术优化研究

西葫芦大孢子离体培养过程中,培养体玻璃化是再生植株形成的主要障碍之一。为保障西葫芦大孢子培养过程中胚状体的正常产生,减少培养体玻璃化对再生植株形成的影响,提高试管苗成活率。本试验通过4种培养基诱导胚状体形成筛选优良诱导培养基,通过对组织培养过程中环境温度、湿度、GA浓度等因子调整来降低培养体玻璃化的发生。结果表明：4种培养基均能不同程度诱导胚状体形成,其中D号B5 40g/LSuc 8g/LAgar 0.5mg/LNAA 0.05mg/LTDZ 30mg/LAgNO3培养基最佳(诱导出胚达96％),且直接生成76％不定芽;在培养温度为25℃,湿度85％,生根培养基GA浓度0.5mg/L条件下西葫芦大孢子培养体玻璃化发生率最低。这项技术在前人基础上完善、优化、建立了最佳的西葫芦未受精子房再生植株技术体系,为后续西葫芦的研究奠定基础。     

江西山药茎尖包埋玻璃化法超低温保存及其遗传稳定性检测

采用植物组织培养法对广丰药薯茎尖的包埋玻璃化法超低温保存程序进行优化,并采用扩增片段长度多态性（AFLP）分子标记法和流式细胞术对其冻后再生苗的遗传稳定性进行检测,同时将超低温程序应用到江西山药其他地方品种,旨在为薯蓣属植物种质资源的长期保存奠定理论基础。结果表明,广丰药薯茎尖预培养的较佳时间为5 d,较佳的蔗糖浓度为0.75 mol·L-1;装载的较佳时间为40 min;脱水的较佳温度为0 ℃,较佳时间为60 min;冻后黑暗培养7 d可以显著提高其成活率。用AFLP分子标记法和流式细胞术对茎尖冻后再生植株的遗传稳定性进行检测,没有发现异常条带和染色体倍性变化,气孔观察也未发现叶下表皮气孔参数的显著变异。将这种超低温保存程序用于江西山药其他基因型,成活率约为40%～85%。该研究建立的包埋玻璃化法超低温保存程序能保证江西山药的遗传稳定性,可为建立江西山药种质资源超低温保存库提供一定的技术支撑。     

玻璃化冷冻对哺乳动物卵母细胞Ca2+的影响机制

卵母细胞冷冻保存是胚胎生物技术(如体外受精、胞浆内单精子注射、体细胞克隆)的重要组成部分,对优良种畜和濒危动物种质资源保存,加速家畜品种改良进程都具有重要意义。与常规冷冻法相比,玻璃化冷冻具有操作简单、降温速率快、耗时短、冷冻效率高等优点,被越来越广泛地应用于家畜卵母细胞的冷冻保存。然而,与新鲜卵母细胞相比,玻璃化冷冻卵母细胞的受精率及发育能力仍不理想,这严重影响了玻璃化冷冻卵母细胞的应用潜力。玻璃化冷冻会引起卵母细胞Ca²⁺浓度升高及钙振荡模式异常,导致其透明带硬化、受精信号紊乱等问题。综合前人研究进展,作者分析了玻璃化冷冻对胞内Ca²⁺浓度、钙振荡模式的影响和作用机制,并指出胞外Ca²⁺内流和胞内钙库Ca²⁺释放是导致冷冻卵母细胞胞内Ca²⁺浓度升高的主要原因,1,4,5-三磷酸肌醇(IP3)Ⅰ型受体分布异常和线粒体损伤可能是导致冷冻卵母细胞钙振荡模式异常的重要原因,以期为正向调控冷冻卵母细胞Ca²⁺浓度及钙振荡模式提供技术参考,从而进一步提高玻璃化冷冻卵母细胞的受精和后续的发育能力。     

Vitrification procedure decreases inositol 1,4,5‐trisphophate receptor expression,resulting in low fertility of pig oocytes

Although cryopreservation of mammalian oocytes is an important technology, it is well known that unfertilized oocytes, especially in pigs, are highly sensitive to low temperature and that cryopreserved oocytes show low fertility and developmental ability. The aim of the present study was to clarify why porcine in vitro matured (IVM) oocytes at the metaphase II (MII) stage showed low fertility and developmental ability after vitrification. In vitro matured cumulus oocyte complexes (COCs) were vitrified with Cryotop and then evaluated for fertility through in vitro fertilization (IVF). Although sperm‐penetrated oocytes were observed to some extent (30–40%), the rate of pronuclear formation was low (9%) and none of them progressed to the two‐cell stage. The results suggest that activation ability of cryopreserved oocytes was decreased by vitrification. We examined the localization and expression level of the type 1 inositol 1,4,5 trisphosphate receptor (IP₃R1), the channel responsible for Ca²⁺ release during IVF in porcine oocytes. Localization of IP₃R1 close to the plasma membrane and total expression level of IP₃R1 protein were both decreased by vitrification. In conclusion, our present study indicates that vitrified‐warmed porcine COCs showed a high survival rate but low fertility after IVF. This low fertility seems to be due to the decrease in IP₃R1 by the vitrification procedure.