精子发生及冷冻过程中表观遗传调控的研究进展

表观遗传调控是不涉及DNA序列改变而引起基因可遗传变化的机制,包括组蛋白修饰、非编码RNAs的调控及DNA特定碱基结构的修饰,它在基因表达过程中起着十分重要的作用。在精子发生过程中,机体通过表观遗传修饰从而确保精子具有正常的功能。冷冻过程会造成精子不可逆的损伤,这些冷冻损伤可能与精子表观遗传变化有关。作者对精子发生及冷冻保存过程中的表观遗传调控机制进行了综述。     

羊驼睾丸细胞凋亡及凋亡相关蛋白的定位

本研究旨在观察羊驼睾丸的出生后发育和精子发生过程中的细胞凋亡及凋亡相关蛋白Bcl2和Caspase3 的定位.取材新生、12月龄和24月龄羊驼的睾丸,用TUNEL法检测睾丸发育和精子发生过程的细胞凋亡,用免疫组织化学技术检测凋亡相关蛋白Bcl2和Caspase3在羊驼出生后发育和精子发生过程中的定位.结果显示在新生羊驼睾丸未检测到TUNEL阳性细胞,Caspase3和Bcl2表达于间质细胞,提示在新生期凋亡蛋白参与间质细胞凋亡的调节,为曲精小管的发育提供空间;12月龄羊驼睾丸TUNEL阳性细胞定位于曲精小管中央部分,Caspase3 和Bcl2定位于间质细胞和曲精小管中央生殖细胞,提示在青春期(12月龄)羊驼睾丸,细胞凋亡和凋亡相关蛋白参与曲精小管管腔形成的调节;24月龄羊驼睾丸TUNEL阳性细胞定位于精原细胞、精母细胞和精子细胞,Caspase3 和Bcl2定位于间质细胞和各个发育阶段的生精细胞,Caspase3阳性细胞在精原细胞最高,向精母细胞和精子细胞逐渐减少,Bcl2在精原细胞弱阳性表达,在血睾屏障以内的曲精小管近腔室部分呈弥散性强阳性表达,提示在性成熟(24月龄)羊驼睾丸精子发生过程中,细胞凋亡主要发生于精原细胞和早期精母细胞,Bcl2可能抑制精母细胞之后生殖细胞的凋亡.结果提示在羊驼睾丸出生后发育和精子发生过程中存在细胞凋亡现象;凋亡蛋白Caspase3和Bcl2参与羊驼睾丸发育和精子发生过程中细胞凋亡的调节.     

冷冻保存对绵羊精子顶体蛋白酶活性的影响

为了检测冷冻保存对绵羊精子顶体蛋白酶活性的影响,试验采用改良的明胶膜片法对冷冻保存前后小尾寒羊精子顶体蛋白酶的活性进行研究。结果表明:冷冻保存后精子顶体蛋白酶阳性反应率[(47.00±2.55)%]和平均成环直径[(23.89±0.22)μm]与冷冻前精子顶体蛋白酶阳性反应率[(77.00±2.00)%]和平均成环直径[(37.26±0.47)μm]相比差异极显著(P<0.01)。说明冷冻保存对绵羊精子顶体蛋白酶活性造成显著性损伤。     

家禽精子冷冻保存技术研究进展

精子冷冻保存技术是一种在体外长期低温保存精子的技术。该技术不仅在人类精子保存方面应用广泛,而且在畜牧业生产和动物保种等领域具有重要意义。然而,目前家禽精子冷冻保存效果还并不理想,大部分精子冷冻复苏后损伤严重,丧失受精能力,限制了该技术的应用和推广。鉴于近年来关于冷冻保护剂、抗氧化剂和药物传递系统在精子冷冻保存技术中的作用,文章从精子冷冻技术的研究历程、冷冻保存程序、冷冻损伤机制和家禽精子冷冻保存液等方面进行综述,为家禽精子冷冻保存技术的研究与应用提供参考。     

细胞凋亡与生精调节关系的研究进展

多细胞生物体的生长、分化、自我更新过程中广泛存在程序性细胞凋亡,表现为染色体浓缩,细胞核内出现空泡,染色体与细胞分解成几个部分,最后再裂解成更多更小的碎片.哺乳动物精子发生是一个细胞高度增殖分化的过程,机体通过介导精原细胞、精母细胞、精子的凋亡机制来保证精子不会无限制分化,并维持精子更新与受精能力 本文重点就钙/镁-依赖性核酸内切酶、核酸酶伴侣ICAD、Caspase家族、ROS、Bcl-2、Bax、Fas、FasL、HSP、HSF、p53等11个因子讨论了细胞凋亡与精子分化关系的研究进展.     

细胞凋亡与生精调节关系的研究进展（续）

多细胞生物体的生长、分化、自我更新过程中广泛存在程序性细胞凋亡,表现为染色体浓缩,细胞核内出现空泡,染色体与细胞分解成几个部分,最后再裂解成更多更小的碎片.哺乳动物精子发生是一个细胞高度增殖分化的过程,机体通过介导精原细胞、精母细胞、精子的凋亡机制来保证精子不会无限制分化,并维持精子更新与受精能力.本文重点就钙/镁-依赖性核酸内切酶、核酸酶伴侣ICAD、Caspase家族、ROS、Bcl-2、Bax、Fas、FasL、HSP、HSF、p53等11个因子讨论了细胞凋亡与精子分化关系的研究进展.     

应激和细胞凋亡对马精液功能和保存的影响

氧化应激是马精子以液体或冷冻精液形式储存的细胞病理学的一个重要问题，精子染色质、细胞膜和蛋白质的损伤是精子氧化损伤的重要组成部分。同样，精子在储存过程中也会受到各种渗透压力，这些压力来自于高渗介质或冷冻过程中引起的渗透性变化。马精子在加工和储存过程中产生的一系列变化也会引起类似凋亡的变化，这些变化可能会对精子存活和功能产生不利影响。这些过程在许多情况下似乎是相互关联的，因此，本文综述了影响马精子功能的应激和细胞凋亡因素。 [关键词]应激|细胞凋亡|马|精液|保存     

抗氧化剂对家畜精液冷冻保存效果的影响研究进展

家畜精液保存在畜牧生产实践中具有十分重要的意义,随着家畜人工授精技术的广泛应用,精液冷冻保存技术研究也更加深入。精液在冷冻保存的过程中,精子细胞会产生过量的活性氧,活性氧与精子细胞膜上的不饱和脂肪酸易发生氧化反应,破坏精子结构和功能的完整性,导致精液品质下降。抗氧化剂具有清除活性氧自由基的作用,可消除精液冷冻过程中所产生的过量活性氧,保护精子细胞免受氧化应激损伤,进而提高精液品质。本文主要对精子冷冻氧化性损伤机制及常用抗氧化剂进行综述,并对抗氧化剂的应用前景进行展望,以期为更进一步提高家畜精液冷冻保存品质,发挥良种优势提供理论依据与参考。     

抗氧化剂在公猪精液冷冻保存中的应用

近几年来,在公猪精液冷冻稀释液中添加抗氧化剂以提高冷冻精液质量的研究受到广泛的关注。添加谷胱甘肽、超氧化物歧化酶和过氧化物酶、维生素E、L-半胱氨酸和L-谷氨酰胺、中草药成分等抗氧化剂可以有效地防止氧化损伤,提高解冻后精子活率、精子成活力、质膜与顶体完整性等,进而提高冷冻保存精液的受精能力。作者综述了抗氧化剂的抗精子冷冻损伤的作用机制及不同抗氧化剂的应用效果,并对其在公猪精液冷冻保存中的应用前景进行了展望。     

影响精液冷冻和人工授精效果的因素

通过对精液冷冻保存的细胞反应原理的阐述 ,指出冷冻保护剂甘油对精液保存具有利弊效应 ,提出精子膜脂组成的差异使得不同品种的精子对冷冻损伤的易感性不同。雌性生殖道解剖结构的品种差异 ,精子形态 ,精子运行机制的细微差异 ,人工授精时间及精子的运行能力 ,采精方式等因素对精液冷冻保存和人工授精的成功有决定性作用。研究精子质膜的生物学特性可解决低活力精子的问题 ,然而这并不能解决冷冻后精子质量的个体差异。对精细胞基因组的研究可以找出这些个体的遗传差异。因此 ,冷冻精子和精原细胞 (用于细胞外注射 )的差异已经成为完整基因组问题。     

Development of avian embryo manipulation techniques and their application to germ cell manipulation

The development of chicken embryo culture techniques, from single‐cell stage to hatching, makes it possible to manipulate developing embryos at any developmental stage. Production of germline chimeric chickens by the transfer of stage X blastodermal cells or primordial germ cells enables the manipulation of germline cells in vitro. Production of transgenic chickens has been attempted by the retroviral vector method, microinjection of DNA into a fertilized ovum at the single‐cell stage, use of chimeric intermediates produced by the transfer of stage X blastodermal cells or primordial germ cells, manipulation of spermatozoa, and in vivo manipulation of gonads. So far, the only non‐viral method that has successfully produced transgenic chickens is microinjection of DNA into a fertilized ovum. Manipulation of primordial germ cells could become an efficient system for producing transgenic chickens by combining it with the highly efficient transfection method or the in vitro culture system for primordial germ cells. Preservation of avian genetic resources has now become possible by cryopreservation of stage X blastodermal cells or primordial germ cells as well as spermatozoa. The development of nuclear transfer techniques for avian species is necessary.     

The apoptosis-necrosis continuum: insights from genetically altered mice

Apoptosis can be defined as a carefully regulated process, characterized by specific morphologic and biochemical features. It is initiated by both physiologic and pathologic stimuli, and its full expression requires a signaling cascade in which caspase activation plays a central role. Knockout mice lacking key genes encoding proteins constituting the core apoptotic cascade have helped us to establish the functional hierarchy of the mechanisms controlling apoptosis in animal development and, to a lesser extent, in disease. Induced mutant mice have also revealed the intimate crosstalk between apoptotic and other homeostatic pathways and have defined distinct temporal and tissue-specific roles of individual apoptotic effectors. Eliminating genes controlling caspase-dependent apoptosis can convert an apoptotic phenotype to a necrotic one, both in vitro and in vivo. This suggests that necrosis and apoptosis represent morphologic expressions of a shared biochemical network through both caspase-dependent mechanisms as well as non-caspase-dependent effectors such as cathepsin B and apoptosis-inducing factor. The cell death program, whether by apoptosis or necrosis, is mediated through an integrated cascade, which can be accessed at multiple sites, and propagated through numerous branch points. An understanding of the physiologic conditions that influence these decisions is required to adequately prevent, or induce, cell death.     

哺乳动物卵母细胞凋亡的研究现状及新进展

细胞凋亡又称程序性细胞死亡,是指机体为维持体内环境的稳定,由基因控制的细胞自主的有序性死亡。对于雌性生殖系而言,细胞凋亡是维持其正常功能的一个重要组成要术。就哺乳动物来说,超过99．9％的雌性生殖细胞会在发育的不同时期发生凋亡。本文主要综述了细胞凋亡的新概念、卵子发生过程中的细胞凋亡现象,同时还对当今卵母细胞凋亡研究的现状及新进展做出了总结。     

Lipotropes (methyl nutrients) inhibit growth of feline lymphoma in vitro

Feline lymphoma is one of the most frequently diagnosed tumors in cats. Lipotropes are dietary methyl donors that may modulate DNA methylation status and the expression of genes involved in growth and apoptosis of feline lymphoma cells. The specific objective of the study was to determine if lipotropes affect the growth of feline lymphoma cells, which entailed examining a correlation between lymphoma cell proliferation and apoptosis. F1B and FeLV-3281 cells were cultured and treated with 20 times the level of lipotropes contained in the basal culture medium. Cell growth and death and caspase 3 and tumor protein p53 activity were measured. Lipotropes were found to significantly reduce cell growth; increased cell death and caspase 3 and p53 activity was seen in F1B cells after 72 h, but the effect was minimal on FeLV-3281. These results could be useful in the development of dietary strategies for treating and preventing feline lymphoma.     

Canine spermatozoa—What do we know about their morphology and physiology? An overview

Spermatozoa are unique cells because of their morphological and physiological characteristics. They are produced during the process called spermatogenesis. Spermatogenesis consists of three phases: spermatocytogenesis, spermiogenesis and spermiation, during which spermatozoa undergo several changes. Spermatogenesis takes place within the seminiferous tubules containing two types of cells—the germ cells and the Sertoli cells—that alongside the Leydig cells, which play an important role when it comes to normal fertility. Everything is regulated by the hypothalamic–pituitary–gonadal axis and specific hormones due to multi-hormonal feedback systems. Spermatozoa possess morphological and physiological features, which are sometimes completely different from what is observed in various somatic cells. What is more, canine spermatozoa have specific characteristics making them special compared to the spermatozoa of other mammalian species. The metabolic energy production, which is crucial for the appropriate functioning of spermatozoa, can be fuelled by different metabolic pathways utilizing different chemical substrates. Inseparable from the oxidative phosphorylation process is the production of reactive oxygen species, which are both essential and toxic to spermatozoa. Furthermore, epididymis is a very important structure, responsible for the transport and maturation of spermatozoa, which are then stored in the last segment of epididymis—the epididymal cauda. Moreover, the retrieval of spermatozoa from the epididymides is crucial for the development of assisted reproduction techniques and sperm cryopreservation methods. The information gained from the research on domestic dogs might be transferred to their wild relatives, especially those species categorized as endangered.     

哺乳动物卵母细胞凋亡机制研究进展

细胞凋亡是细胞程序性死亡过程,在生殖细胞的发生过程中具有重要作用。哺乳动物卵母细胞在生长发育过程中,除排卵受精的成熟卵母细胞外,其他卵母细胞在卵泡发育的不同阶段凋亡。作者综述了卵母细胞的发育与细胞凋亡、细胞凋亡的主要参与分子及凋亡途径等研究进展,旨在为进一步研究哺乳动物卵母细胞的生长、发育和排卵机制提供帮助。     

Advance of Apoptotic Mechanism in Mammalian Oocyte

Apoptosis is programmed cell death process, which plays an important role in the process of development of germ cells. In the process of growth and development of mammalian oocytes, in addition to the mature ovulation fertilization of the oocytes, the others are apoptotic at different stages of follicular oocytes. This paper summarizes the research progress of development of the main apoptosis mechanism and apoptosis pathway of mammalian oocytes, and lays a foundation for further studying growth, development and ovulation mechanism of oocytes.     

哺乳动物生殖细胞冷冻保存对其DNA甲基化影响的研究进展

哺乳动物生殖细胞和胚胎冷冻保存在辅助生殖技术中得到了广泛的应用,同时在保存物种的多样性方面发挥着巨大的作用。但是,冷冻引起的DNA甲基化对其印记基因缺陷性疾病的发生和后代生理功能的差异会有很大的影响。作者就冷冻保存技术对配子（精子和卵子）和胚胎的DNA甲基化的影响以及冷冻引起的DNA甲基化对后代的影响进行了综述,以期对配子的冷冻保存和辅助生殖技术的发展提供参考。     

Research Progress on the Relationship between Cryopreservation of Mammalian Germ Cells and Their DNA Methylation

Cryopreservation of mammalian germ cells and embryos has been widely used in assisted reproduction. It also plays an important role in preservation of species diversity. DNA methylation abnormality induced by freezing in germ cells or embryos has an significant impact on the occurrence of disease and the physiological function of the offspring. In this paper, we summarize the effects of cryopreservation of mammalian germ cells and embryos on their pattern of DNA methylation which in turn make the developmental deficiency in the progeny from these gametes or embryos. Finally, it will provide the reference on the gamete cryopreservation and the development of assisted reproductive technology.