Cyclin-CDK-CKI及UPP参与生殖调控及在甲壳动物性腺发育中的研究进展

Cyclin-CDK-CKI是参与真核细胞周期调控的3个重要的调节因子。泛素蛋白酶体途径(ubiquitin proteasome pathway,UPP)是真核细胞内非溶酶体途径的蛋白质选择性降解的重要途径。细胞周期中许多时相特异性周期蛋白通过泛素化被周期性的降解对于细胞分裂的调控进程具有重要的作用。主要综述了Cyclin-CDK-CKI和UPP的组成、生理生化特性及其参与生殖调控的作用机制,同时阐述了这两大系统之间的联系及其在甲壳动物性腺发育中的研究进展。     

RNAi在甲壳动物中的研究进展

RNA干扰（RNA interference,RNAi）是一类在真核生物中广泛存在的,由双链RNA介导的转录后基因沉默机制。作为一项研究基因功能的有力工具,RNAi技术已经被广泛应用在线虫、果蝇、斑马鱼和小鼠等生物的基因组学研究中。近来在甲壳动物中,通过RNAi技术取得了众多的科研成果。文章从免疫、生长发育、蜕皮、生殖、性别调控、渗透压调节和代谢等几个方面进行了综述。进而对RNAi技术在甲壳动物中的研究前景进行了展望,旨在为以后更好地研究甲壳动物的基因功能和调控网络提供参考。     

甲壳动物蜕皮抑制激素调控机制的研究进展

甲壳动物的蜕皮过程主要是由Y器(Y-organ)分泌的蜕皮类固醇激素与X器-窦腺复合体(X-organ-sinus gland,XO-SG)分泌的蜕皮抑制激素MIH相互拮抗而进行调控的。而MIH调控机制较为复杂,且存在争议。本文就MIH调控机制的研究进展,包括研究方法,以及目前调控机制中争议最大的3个问题:MIH受体、cAMP与cGMP功能以及Ca2+功能作一综述。     

广西海域靓巴非蛤性腺发育和生殖周期的初步研究

通过靓巴非蛤(Paphia schnelliana)性腺发育以及肥满度周年变化情况确定其繁殖期,为靓巴非蛤人工繁育工作的开展积累第一手资料。实验结果表明靓巴非蛤性腺发育周期为1年,对于繁育的亲本而言,不存在大小卵共存的现象,且其生殖细胞为一次性排放。靓巴非蛤肥满度与其性腺的变化密切相关。每年的4至5月份和9至10月份是靓巴非蛤的繁育期,因此这段时间是开展人工育苗工作的最佳时期。     

斑马鱼性腺发育的组织学观察

在过去几十年,斑马鱼(Danio rerio)由于其发育周期短且速度快,胚胎发育透明,已经成为众多研究领域的典型模式生物.斑马鱼的性腺发育和分化非常特殊,雄性和雌性幼鱼的性腺在早期全部发育成"类卵巢"结构.目前,对于斑马鱼的性别分化和性腺分化机制还不清楚.本文以孵化后不同时期的斑马鱼仔鱼和幼鱼的生殖腺为材料,经石蜡切片和苏木精染色后,荧光显微镜下观察了斑马鱼仔鱼性腺从出现、分化到成熟的发育过程.结果发现:孵化后5～10日龄仔鱼腹腔两侧可以观察到没有分化的生殖腺,其中的生殖细胞明显比周围的体细胞大;孵化后14～24日龄仔鱼的生殖腺中可见由卵原细胞分裂形成的生殖包囊,其中的生殖细胞进一步分化、分裂形成体积更大、数量更多的卵母细胞;25日龄左右的仔鱼,其性腺成为在腹腔两侧对称,而且在组织结构上也较为典型的卵巢样结构.到35日龄前后可见一部分仔鱼的性腺逐步由卵巢样结构向精巢结构转变的过程.我们在2周左右的仔鱼的性腺中观察到了生殖包囊存在,这一现象还未见有前人报道.在本试验中,我们不仅清楚地观察到类似卵巢的性腺中"卵母细胞"逐渐凋亡消失的过程,还观察到性腺由最初的类似卵巢样结构逐渐变成典型的精巢结构的整个过程.这些研究成果将为发育生物学提供有价值的信息和第一手资料.     

PIWI/piRNA介导表观遗传学调控在生殖细胞发育中的作用

piRNA(PIWI-interacting RNA)是主要在生殖细胞系中表达的一类由21～33个核苷酸组成的单链非编码RNA,与PIWI蛋白结合而发挥调控作用.研究显示,PIWI/piRNA不仅可以在细胞质里对mRNA直接进行剪切和降解,还能招募大量的表观遗传学修饰蛋白介导基因组和组蛋白的表观遗传学调控关闭基因,促进...     

鱼类性腺发育研究新进展

为了探讨鱼类性腺发育规律,过去进行了大量性腺发育的组织学和组织化学研究。目前用电镜,免疫、离体培养和分子生物学技术,进一步研究了性腺发育过程和它的机能分化,产生一些新的概念。本文主要综述近年来这方面的研究       

甲壳动物的类固醇激素及其对卵巢发育的作用

如何促进虾蟹的卵巢发育是经济甲壳动物养殖中的重要问题.对于这一问题的解决尚在探索之中.如果使用外源激素能达到这一目的,无疑是方便的.为此,对甲壳动物中的类固醇激素及其作用进行了较多的研究.     

青海湖裸鲤性腺发育的组织学研究

采用石蜡组织切片法,对青海湖裸鲤的性腺发育进行组织学研究,系统地描述了各期卵巢和精巢的形态结构、特征及变化。结果表明:(1)青海湖裸鲤性腺的发育可分为六个时期,卵母细胞从第3时相发育到第4时相基本同步。第Ⅳ期末卵巢,第4时相卵母细胞的卵径大小比较整齐,卵径平均值为2.3mm,第4时相卵母细胞占切面上卵数的85%以上,占切片面积的96%以上,第2、3时相卵母细胞已很少;(2)产后卵巢的组织结构逐步由第Ⅵ期回复到第Ⅱ期,再由第Ⅱ期到第Ⅲ期向第Ⅳ期过渡;(3)性成熟个体有68.12%的雌鱼和83.9%的雄鱼以第Ⅳ期性腺越冬,另有21.01%的雌鱼和10.7%的雄鱼以第Ⅲ期性腺越冬,还有10.87%的雌鱼和5.4%的雄鱼以第Ⅱ期性腺越冬。根据青海湖裸鲤各季节性腺发育情况,作者认为青海湖裸鲤已达到性成熟的个体并不是每年都参与繁殖活动,存在生殖间断性。这反映了青海湖裸鲤的繁殖习性对高原寒冷多变气候的适应性。还对卵黄核和核仁在卵黄形成中的作用以及青海湖裸鲤的产卵类型和生殖间断性进行了讨论。     

病毒利用UPP逃避抗病毒反应的研究进展

泛素-蛋白酶体途径是溶酶体外蛋白降解的主要系统,在许多细胞功能中发挥重要作用。越来越多的证据表明病毒参与泛素-蛋白酶体途径,干扰IFN信号通路和免疫受体表达、凋亡抑制及介导病毒潜伏。深入理解病毒利用泛素-蛋白酶体途径逃避宿主抗病毒反应的策略,有助于揭示病毒的致病机理和鉴定抗病毒药物新靶标。     

The Role of Juvenile Hormones in Crustacean Reproduction

SYNOPSIS. Similar to juvenile hormone production in adult insects,the production of methyl farnesoate (MF) seems to be relatedto reproduction in both sexes in mature crustaceans. The mandibularorgan (MO) synthesizes MF, and its activity corresponds to reproductivestages. High MF levels in the blood are found in vitellogenicfemales and reproductively active males. Conversely, low levelsare found in immature females, non-vitellogenic females, andmales that are in reproductive diapause. The MO is under inhibitorycontrol by neurosecretory factors from the sinus gland locatedin the eyestalks, and may be stimulated by factors from thebrain and/or thoracic ganglion.     

Regulation of the Crustacean Mandibular Organ

The crustacean mandibular organ (MO) produces methyl farnesoate(MF), a juvenile hormone-related compound thought to have rolesin crustacean reproduction and development. Therefore, the controlof MF production by the MO has been of considerable interest.Current evidence indicates that the MO is negatively regulatedby peptides present in the eyestalk (MO inhibiting factor, MO-IH).Several eyestalk neuropeptides have been identified that inhibitMF synthesis by MO incubated in vitro. The amino acid sequencesof these MO-IH peptides are similar to peptides in the crustaceanhyperglycemic hormone (CHH) family of neuropeptides. In addition,there appears to be a compound in the eyestalk that lowers hemolymphlevels of MF in vivo but does not directly affect the MO invitro. The inhibition of MF synthesis by eyestalk peptides involvesthe inhibition of farnesoic acid O-methyl transferase, the lastenzyme in the MF biosynthetic pathway. The activity of thisenzyme is affected by cyclic nucleotides, suggesting that thesecompounds may be involved in the signal transduction pathwaymediating the effects of MO-IH.     

Behavioral Cost of Reproduction in a Freshwater Crustacean (Eulimnadia texana)

It is commonly noted that investments in reproduction, both physiological and behavioral, can trade off with other life‐history traits, such as growth and survival. In males, behavioral reproductive activities (e.g., copulations) are associated with weight loss, increased predation risk, reduced future reproductive output, and decreased lifespans. It is uncommon to find species in which increased copulations actually increase survival. Herein, we examine one such species, the androdioecious (males + hermaphrodites) crustacean Eulimnadia texana, in which increased copulations have been associated with increased lifespan. We examined two potential causes of this association: (1) males not copulating actually expend significant energy by searching for mates and (2) males are experiencing shorter lifespan primarily because they are more inbred than hermaphrodites. We found that isolated males did indeed expend more energy than hermaphrodites, consistent with previous studies showing that males swim over twice as much as hermaphrodites when isolated. Additionally, although inbreeding was associated with reduced lifespan, outcrossed males still had shorter lifespans relative to outcrossed hermaphrodites. Thus, isolated males consistently show decreased lifespans relative to isolated hermaphrodites, which is not explainable only on the basis of level of inbreeding. We conclude that the costly searching behavior of these males is the likely underlying cause of this observed difference in lifespan between the sexes, as previously suggested.     

Regulation of Release and Mode of Action of Crustacean Chromatophorotropins

Pigment movements in crustacean chromatophores are regulatedby pigment-concentrating and pigment-dispersing neurosecretoryhormones. The release of these hormones from the neurosecretorysystem is thought to be controlled by neural signals. Althoughthe exact cellular sources of chromatophorotropins and the natureof synaptic input to the neurosecretory system remain unresolved,recent pharmacological studies on fiddler crabs indicate thatcertain biogenic amines contribute to the release of some ofthe chromatophorotropins. The current evidence suggests that:5-hydroxytryptamine stimulates the release of RPDH (red pigmentdispersing hormone), dopamine triggers the release of RPCH (redpigment concentrating hormone), and norepinephrine stimulatesthe release of BPDH/MDH (black pigment/melanin dispersing hormone).Nothing is known of the regulation of release of leucophorotropinsand xanthophorotropins. Like most other peptide hormones, crustacean chromatophorotropinsare thought to exert their effect by first binding to receptorson the cell surface and then triggering a series of events leadingto cellular responses, but the details are far from clear. Recentwork suggests that hormone-induced pigment movements may bemodulated/mediated by alterations in cyclic nucleotide levelsand/or by changes in Ca²⁺ distribution or flux. Both cyclicnucleotides and Ca²⁺ may modulate motility by regulating theintegrity and/or function of cytoskeletal elements, but thedetails of this mechanism and the precise roles of cytoskeletalelements in the pigment-translocating process remain unresolved.     

Ran and Calcineurin Can Participate Collaboratively in the Regulation of Spermatogenesis in Scallop

Calcineurin is a calcium/calmodulin-dependent protein phosphatase that plays important roles in the transduction of calcium signals in a variety of tissues. In addition, calcineurin has been implicated in the process of spermatogenesis. A novel calcineurin-binding protein, CaNBP75, has been identified in scallop testis. The C-terminal region of CaNBP75 is homologous to the C-terminal region of RanBP3, a Ran-binding domain-containing protein. A small G protein Ran has been involved in spermiogenesis by virtue of the fact that its localization in spermatids changes during spermiogenesis. The current study was performed to investigate the functions of Ran and CaNBP75 in the regulation of calcineurin in testis to further understand the basic functions of calcineurin during spermatogenesis. First, cloning and sequencing of a scallop Ran cDNA isolated from testis revealed that scallop Ran is well-conserved at the amino acid level. Secondly, direct binding of Ran to CaNBP75 was demonstrated in an in vitro pull-down assay. Thirdly, analysis of the tissue distribution of Ran, CaNBP75, and calcineurin showed that these proteins are abundantly expressed in testis. Fourthly, comparison of the expression profiles of Ran and CaNBP75 with that of calcineurin in scallop testis during the maturation cycle revealed that Ran and CaNBP75 mRNA levels increase during meiosis and spermiogenesis, similar to calcineurin. Finally, co-immunoprecipitation analysis suggests that Ran, CaNBP75, and calcineurin interact in scallop testis during maturation. These results suggest that Ran, CaNBP75, and calcineurin may act in a coordinated manner to regulate spermatogenesis.     

Seasonal Regulation of Reproduction in Muroid Rodents

This paper offers a conceptual scheme dealing with the way environmentalfactors influence reproduction in muroid rodents. The combinationof small size, short life span, and the fact that most environmentsare relatively unpredictable for short-lived animals, suggeststhat opportunism must be a key element in the reproductive strategiesof most of these animals. Flexibility is assured by the useof dynamically changing multiple reproductive strategies withinpopulations, simultaneous multiple cueing in individuals, modificationof an individual's responses to these cues by earlier experiences,and the use or lack of use of predictors of different kinds.