甲壳动物精子学研究概况Ⅰ.精子的形态与结构

甲壳纲是整个动物界中物种最为丰富的一个纲,其精子形态、结构各异.八个亚纲(按椎野1964年的分类系统)中的三个亚纲--须虾亚纲(Mystacocaride)、蔓足亚纲(Cirripedia)、鳃尾亚纲(Branchiura)的精子具鞭毛,能运动.其它五个亚纲的精子形状各不相同,无鞭毛且不运动.自上世纪后半叶以来,已在光镜水平进行了大量的研究.近年来,对其亚微结构的研究正不断深入.电镜细胞化学、免疫学、分子生物学等相关学科的渗透,更为甲壳动物精子学研究提供了新手段,开拓了新领域.全文分两部分,从精子的形态结构、精子发生及精子的生化组成等方面概述甲壳动物的精子学研究进展.本文着重阐述精子的形态与结构.     

甲壳动物的生殖量与环境关系：Ⅱ.桡足类

本文是《甲壳动物的生殖量与环境关系》系列论文的第二篇,专述桡足类。它和枝角类一样,是一类小型低等甲壳动物,也是浮游生物群落的一个重要组成部分。种类多、数量大、分布广是它的生态特点。由于生活习性不     

甲壳动物精子学研究概况 Ⅰ精子的形态与结构

甲壳动物精子学研究概况Ⅰ精子的形态与结构王艺磊１,２）张子平３）李少菁２）（集美大学水产学院养殖系１）厦门３６１０２１）（厦门大学海洋学系２）厦门３６１００５）（香港城市大学生物与化学系３）九龙香港）关键词甲壳动物精子形态结构甲壳纲是整个动物界中...     

中国鲎精子发生的研究: Ⅰ.精子的发生过程

利用光镜和电镜技术,结合细胞化学方法研究了中国鲎（Ｔａｃｈｙｐｌｅｕｓ ｔｒｉｄｅｎｔａｔｕｓ）精子发生过程．结果表明：中国鲎精子发生可划分为精原细胞、初级精母细胞、次级精母细胞、精子细胞及精子五个时期。在精子发生中,出现顶体丝结构,这是鲎精子发生的一个重要特征。页体由顶囊和亚顶体间隙组成。顶体丝由顶体囊底部发出,穿过亚顶体间隙,贯穿核中央部分的通道．沿核底部穿出,绕核缠绕,形成约２８匝的百体丝螺圈。这一特点可能与精子在受精时必须穿越厚的卵膜密切相关。成熟精子头部如梨形,前端覆盖有吸盘状后帽,头部长约４μｍ,尾部鞭毛长达３５μｍ、鞭毛为９ ×２结构,在鞭毛基部有一对中心粒。     

牦牛心包材料的生化组成

牦牛是我国重要的生物资源,用牦牛心包缝制的心脏瓣膜可用于置换病变严重或坏死的天然心脏瓣膜.本文分析了牦牛心包材料的生化组成,从其生化组成上论证了牦牛心包用作心脏瓣膜材料的可行性.     

稀有鮈鲫及其饲料的生化组成研究

研究了稀有的鮈鲫鱼肌、性腺的生化组成,肌肉中水分含量为79.12-79.65％,蛋白质为68.39-70.20％,脂肪为20.11-20.65％,灰分为15.88-16.04％,能值为19.91-20.84Kj/gdm。鱼肌中含17种氨基酸,必需氨基酸占19.45-20.13％,极性氨基酸占17.23-17.45％,非极性氨基酸占17.51-18.16％,鱼肌中Ca、Na、P、Mg、Zn、Fe含量均较高,此外还测定了稀有的鮈鲫的活饵-水蚯蚓及人工饲料的生化组成。     

罗氏沼虾精子棘状部的结构生化组成和功能

作者探讨了罗氏沼虾精子棘状部的组成,生化成分和受精时所起的作用。棘状部主要由具周期性横纹的纤丝组成,在近尖端横切面的中央有絮状颗粒存在。棘状部Ｆｅｕｌｇｅｎ反应呈阴性,不含核物质,而ＨｇＢｐＢ反应呈强阳性,蛋白质含量很高。     

菲律宾蛤仔的精子发生和精子超微结构

用透射电镜研究了菲律宾蛤仔(Ruditapes philippinarum)精子结构和精子发生过程中细胞形态结构的变化及细胞器的演变规律。菲律宾蛤仔雄性生殖细胞的形态由椭圆形渐变为辣椒状,细胞核的形态由椭圆形逐渐拉长,渐变为锥形。染色质的凝集经历：小颗粒团块状一较大颗粒均匀状一粗颗粒均匀状的过程。线粒体在演化过程中数量先增多后逐渐减少,嵴数逐渐增多,电子密度和体积逐渐增大。高尔基体在初级精母细胞期已经发育,随后的各期中发育良好,分泌旺盛。精细胞Ⅱ期,高尔基体分泌的潴泡开始融合,形成前顶体囊。精细胞Ⅲ期,高尔基体的分泌物仍不断融合。精细胞分化的后期,前顶体囊逐渐发育形成顶体。菲律宾蛤仔成熟精子呈长辣椒状,为原生型,由头部、中段和尾部构成。头部的顶体为细长柱形,末端渐细,电子密度较小;细胞核为锥形;中段线粒体4个,尾部鞭毛为典型的“9 2”型结构。此外在成熟精子线粒体环横切面有一特殊“风车状”结构。     

球形念珠藻的生化组成分析

测定了葛仙米的生化组成,结果表明,葛仙米的蛋白、氨基酸和总糖含量分别为28．33％、23．35％和24．19％;灰分和粗脂肪原含量分别为14．63％和5．34％;还含有较为丰富的粗脂肪和无机元素,特别是钙、镁元素的含量较高。     

Temperature Affects Stoichiometry and Biochemical Composition of Escherichia coli

Temperature is a master variable controlling biochemical processes in organisms, and its effects are manifested on many organizational levels in organisms and ecosystems. We examined the effects of temperature on the biochemical composition and stoichiometry of a model heterotrophic bacterium, Escherichia coli K-12, held at constant growth rate in chemostats. Increasing temperature led to increased cellular organic carbon (C) and organic nitrogen (N) with decreased phosphorus (P) content, leading to increased C/P and N/P biomass ratios. P content was related to cellular RNA, which is P-rich (9–10% by weight) and nonnucleic acid P (presumably composed of mostly phospholipids, intracellular phosphate, and polyphosphate). These results indicate that E. coli allocates an increased proportion of its P cell quota toward assembly (ribosomes) at low temperatures and an increasing proportion toward resource acquisition machinery (membranes) at higher temperatures. If these results are relevant to the behavior of prokaryotic heterotrophs in natural settings (the gut, soils, lakes, oceans, etc.), it suggests greater nutrient regeneration and less microbial nutrient retention as temperatures increase.     

Spermatogenesis revisited

Summary This ultrastructural study confirms and extends the light microscope findings of Bryan (1971) concerning the presence and developmental fate of multinucleate spermatids. Four main classes of cells: uninucleate-individual, uninucleate-conjoined, multinucleate-conjoined, and multinucleate-individual, were identified along with a few instances of more complex syncytial organizations. When the respective nuclei in a given multinucleate are far enough apart, each develops autonomously but in synchrony with its neighbors. When nuclei are intimately associated, the normal pattern of spermiogenesis may be altered, giving rise to highly bizarre spermatozoa. Commonly, a single Golgi complex serves a pair of nuclei and gives rise to a T-shaped acrosome which binds the nuclei together. During the ensuing nuclear elongation phase, such units are invested by a single manchette. Pairs of axonemes within a common plasma membrane have also been encountered. These ultrastructural findings indicate that multinucleate spermatids are true components (not artifacts) of the seminiferous epithelium of normal animals. The presence of such cells and the unusual developmental consequences which can arise as a result of the multinucleate state must be taken into account when evaluating the course of spermatogenesis in cases of mutation- or chemically-induced infertility.These studies have been supported by funds from The Office of General Research, The University of Georgia.     

Spermatogenesis revisited

Summary Gametogenesis is normal through meiosis and the earliest phases of spermiogenesis in male-sterile mice homozygous for the recessive, pleiotropic, mutation hpy (hydrocephalic-polydactyl). However, structurally complete sperm flagella were not encountered. Instead, partially assembled axonemal structures and/or poorly organized aggregates of other tail components (mitochondria, outer coarse fibers) were seen at the posterior poles of nuclei in older spermatids. The ultrastructure of centrioles in spermatids was normal, but that of axonemes associated with them was not. These findings suggest that the observed flagella dysgenesis results from defects in assembly rather than from defective intiation centers. Released gametes usually consisted of distorted nuclei and associated acrosome enclosed in a relatively close fitting plasma membrane. Perturbations of sperm head development were also encountered; they included extreme nuclear elongation, and distortion of the acrosome and underlying nuclear material by inpushings of finger-like processes of Sertoli cells. It is believed that sperm head anomalies are secondary consequences of the mutant condition. The findings support the view that the hpy locus represents one of a number of genes primarily involved in the mediation of flagella development.Aided by a grant from The National Foundation-March of DimesA preliminary account of some of the findings was presented elsewhere (Bryan, 1976)The author wishes to express his thanks to Mrs. Charla Danforth and Mr. James Barrows for capable technical assistance, to Dr. Walter J. Humphreys, Director, The Central Electron Microscope Laboratory, University of Georgia, for use of the facility, and to Dr. Willard F. Hollander, Iowa State University, for original breeding stock and helpful discussions     

The Spermatozoon of Siboglinum (Pogonophora)

The spermatozoon and some spermatid stages of Siboglinum (Pogonophora) have been examined by light and electron microscopy. In the spermatozoon a helical acrosome, a helical nucleus and a “body” with axonema follow each other in normal sequence. Head and tail are joined by a very short neck region containing two modified centrioles. The posterior portion of the nucleus is surrounded by a mitochondrial sheath consisting of three tightly wound mitochondrial helices. In the main portion of the tail the 9+2 unit is sorrounded by a granular sheath of dense material. In the neck region a centriole adjunct develops into a dense substance containing about nine rods. At an early stage, when the centriolar apparatus and flagellum become associated with the nucleus, three large mitochondria with fairly regular cristae are seen at the base of the nucleus. A well developed Golgi apparatus is present in early stages. Rows of microtubules are observed encircling the spermatid nucleus. Compared with the primitive type of spermatozoon the pogonophore sperm shows elongated and specialized nucleus, acrosome and mitochondria. It is concluded that the ancestral form must have had a fairly primitive spermatozoon and that evolution has proceeded towards a modified sperm with complicated spiral structure in connection with the evolution of a modified biology of fertilization, viz. specialized spermatophores. It is not known how the spermatophore discharges the spermatozoa nor how the spermatozoa find their way to the eggs. Two kinds of sperms are produced in the gonads of Siboglinum. The atypical sperm is smaller than the typical one.     

翡翠贻贝精子的超微结构

利用透射电镜研究翡翠贻贝 (Pernaviridis)精子的超微结构。精子为典型的原生型 ,包括头部、中段与尾部三部分。头部由顶体和细胞核组成。顶体明显突出呈倒漏斗形。亚顶体腔呈锥形 ,其中的亚顶体物质呈伞状分布 ,中轴一直延伸至核的后端。细胞核近似球形 ,被管状的核前窝几乎分成相似的两部分。 4～ 5个椭圆形的线粒体围绕着中心粒复合体形成精子的中段。中心粒为中空的圆柱形 ,具有卫星体结构。尾部细长 ,轴丝为典型的“9 2”结构。本文讨论了双壳类精子形态的种属间的差异。