泥鳅精子入卵的动力作用

在扫描电镜下,泥鳅成熟卵卵膜孔外围呈现完整的左涡旋状结构,受精时精子是顺着涡旋的流线进入卵膜孔。涡旋纹理接近对数螺线。本文分析了真骨鱼类的受精因素,除已知的化学因素外,还存在物理因素。也讨论了泥鳅成熟卵卵膜孔形态形成的必然性。     

唇鲳精子早期入卵观察

用扫描电镜对唇鳃成熟卵子及早期精子人卵过程进行观察。结果显示,唇鲋成熟卵子在动物极中央有一深凹陷的表面光滑的精孔器,其外径2．512μm,内径2．330μm,精子直径1．567μm。混匀的精卵刚遇水时,没有精子进入精孔器。受精后1s,精孔器内出现精子。受精后5S,组织切片显示,精子已经进入卵子内,并形成具有强烈抑制多精人卵作用的受精锥。受精后10S,精子在精孔器前庭集结,尚未形成受精塞。受精后20S,在精孔器内形成受精塞。受精塞没有阻塞精孔管,经分析它不是来源于皮层反应产物。受精塞形成后,可以吸附人卵的精子,这对多精入卵有积极的抑制作用;精子尾部在入卵过程中相互缠绕,这也是减少多精入卵的重要机制。受精后30s,受精塞和吸附的精子向精孔器外移动。受精后50S,受精塞和吸附的精子堵塞精孔器。受精后60s,受精塞吸附的精子开始解体,但是由于精孔管未封闭,还有精子通过精孔管进入到质膜。在人工受精过程中,卵子的单精受精屏障会因其周围精子密度大、精子与卵子距离短、精子运动速度快而被打破,从而导致这些卵子出现多精入卵的现象。受精后80s,精孔管仍然没有封闭,精孔器附近的精子明显出现活动能力的差异：精孔器外面的精子活动能力最强,精孔管旁边的精子活动能力较弱;精孔管外堆积的精子活性消失,受精塞吸附的精子已开始解体,经初步分析,这可能是进入其内的精子耗能有所差异的结果。受精后100S,受精塞吸附的精子解体。     

唇精子早期入卵观察

用扫描电镜对唇成熟卵子及早期精子入卵过程进行观察.结果 显示,唇成熟卵子在动物极中央有一深凹陷的表面光滑的精孔器,其外径2.512 μm,内径2.330 μm,精子直径1.567 μm.混匀的精卵刚遇水时,没有精子进入精孔器.受精后1 s,精孔器内出现精子.受精后5 s,组织切片显示,精子已经进入卵子内,并形成具有强烈抑制多精入卵作用的受精锥.受精后10 s,精子在精孔器前庭集结,尚未形成受精塞.受精后20 s,在精孔器内形成受精塞.受精塞没有阻塞精孔管,经分析它不是来源于皮层反应产物.受精塞形成后,可以吸附入卵的精子,这对多精入卵有积极的抑制作用;精子尾部在入卵过程中相互缠绕,这也是减少多精入卵的重要机制.受精后30 s, 受精塞和吸附的精子向精孔器外移动.受精后50 s, 受精塞和吸附的精子堵塞精孔器.受精后60 s, 受精塞吸附的精子开始解体,但是由于精孔管未封闭,还有精子通过精孔管进入到质膜.在人工受精过程中,卵子的单精受精屏障会因其周围精子密度大、精子与卵子距离短、精子运动速度快而被打破,从而导致这些卵子出现多精入卵的现象.受精后80 s, 精孔管仍然没有封闭,精孔器附近的精子明显出现活动能力的差异:精孔器外面的精子活动能力最强,精孔管旁边的精子活动能力较弱;精孔管外堆积的精子活性消失,受精塞吸附的精子已开始解体,经初步分析,这可能是进入其内的精子耗能有所差异的结果.受精后100 s,受精塞吸附的精子解体.     

几种蛾类卵的受精孔管

在长期演化的历史进程中.昆虫的成熟卵母细胞获得了由滤泡细胞分泌的卵壳蛋白凝聚固化而成的卵壳所包被起来.卵壳具有保护性等多种生理功能(夏邦颖1982)。在卵壳上有受精孔和和气孔分布,在鳞翅目等昆虫卵壳上的受精孔周围。有受精孔区花饰特征.这种结构对卵在受精时有聚拢精子游向受精孔的作用.昆虫学家们利用卵的受精孔区花饰特征作为昆虫卵分类的依据(D(o|¨)hing 1955,Hinton1970,Downey 1980.1981夏邦颖1980)。笔者在近年的研究工作中注意到昆虫卵由受精孔向卵内延伸的结构——受精孔管.曾在扫描电镜首     

黄颡鱼受精早期精子入卵扫描电镜观察

用扫描电镜对黄颡鱼(Pseudobagrus fulvidraco)成熟精、卵及授精早期精子入卵过程进行了观察。成熟精子为鞭毛型形态,全长为11·2～12·4μm,头部直径1·1～1·3μm,鞭毛长10·0～11·3μm。成熟的黄颡鱼卵呈圆形,具单一受精孔,卵膜上以受精孔为中心分布有无数辐射状沟嵴。授精前,受精孔暴露在外面;授精2s时,受精孔被纤维状物质覆盖,之后大量精子很快黏附在覆盖物上;至授精10s,漏斗状受精孔又暴露出来。黄颡鱼在授精10s～1min内完成精子入卵过程,可观察到几乎所有样品的精孔区出现一圈环状隆起。大量精子处于隆起外侧,只有少数越过隆起到达受精孔前庭。授精1·5min,精孔区的隆起变成两圈,精子鞭毛解体。授精3min,可见迟到的精子被挡在外面。授精5min,精孔区的精子头部解体,受精孔几乎被分泌物覆盖,受精塞清晰可见。至授精20min,精子几乎全部解体。讨论了精子入卵的动力作用、精卵识别和单精受精机制。     

蕨受精作用的细胞学观察（英文）

为了阐明进化蕨类受精作用的特点和细胞学机制,该文采用透射电镜观察了蕨(Pteridium aquilinum var.latiusculum)受精作用的主要过程,观察结果显示:(1)蕨精子通过受精孔进入卵细胞,多数情况下,该精子的螺旋运动先在受精孔的下方产生一个受精腔,然后精子再与卵细胞质融合。(2)第一个精子的这种延迟的螺旋运动和因精子的钻入而引起的卵细胞固缩反应可能是阻止多精受精的重要因素。(3)卵发育时期产生的核外突在受精后仍能持续12h,然后与核本体分离,逐渐在细胞质中消解。(4)合子通过其后方细胞质的液泡化而建立了水平极性,此后再进行细胞分裂。该研究观察到了进化蕨类受精作用过程中的一些新现象,包括产生受精腔、卵细胞固缩反应、核外突的命运以及合子极性建立等,这有助于理解蕨类植物的受精作用机制及有性生殖的演化。     

人工复合三倍体鲤鱼多精受精的细胞学基础研究(英文)

为了获取一个可育的、没有遗传分离的、快速生长的养殖品系,我们通过人工方法诱导了人工复合三倍体鲤鱼。它含有两套鲤鱼（一套是散鳞镜鲤、一套是兴国红鲤）和一套鲫鱼（红鲫）共三套完整的染色体组。在这种复合三倍体中,发现有些受精卵具有罕见于硬骨鱼类中的受精生物学现象,即多精受精。这是一个非常有趣的生物学现象。为了了解其潜在的机制,我们以普通红鲤作为父本、经过干法授精,通过扫描电子显微镜对其受精的早期过程进行了超微结构研究,并以普通二倍体鲤鱼受精的早期过程作为对照。（１）通过对三次产卵季节收集的近１０００余粒未受精的成熟人工复合三倍体卵细胞进行观察,发现：每个成熟卵子在其动物极上只有一个敞开的受精孔。它由前庭和精孔管组成。前庭对外开口的平均半径为１０～１２微米。精孔管的外孔径为３．００～３．５０微米（Ｆｉｇ．Ａ＆Ｂ）,只比精子头部直径（２．８０～３．００微米）稍大一点。排除了人工复合三倍体鲤鱼成熟卵细胞一次允许两个精子并排进入的可能性。（２）人工复合三倍体鲤鱼在受精后约１５～３０秒,可以看见大量精子聚集在受精孔的前庭区域（Ｆｉｇ．Ｃ）。而在卵子表面的其它区域,没有发现有精子附着的现象。表明：在受精孔的前庭区域有一些吸引     

蕨受精作用的细胞学观察

为了阐明进化蕨类受精作用的特点和细胞学机制,该文采用透射电镜观察了蕨(Pteridium aquilinum var.latiusculum)受精作用的主要过程,观察结果显示:(1)蕨精子通过受精孔进入卵细胞,多数情况下,该精子的螺旋运动先在受精孔的下方产生一个受精腔,然后精子再与卵细胞质融合。(2)第一个精子的这种延迟的螺旋运动和因精子的钻入而引起的卵细胞固缩反应可能是阻止多精受精的重要因素。(3)卵发育时期产生的核外突在受精后仍能持续12 h,然后与核本体分离,逐渐在细胞质中消解。(4)合子通过其后方细胞质的液泡化而建立了水平极性,此后再进行细胞分裂。该研究观察到了进化蕨类受精作用过程中的一些新现象,包括产生受精腔、卵细胞固缩反应、核外突的命运以及合子极性建立等,这有助于理解蕨类植物的受精作用机制及有性生殖的演化。     

异源四倍体鲫鲤的受精细胞学

异源四倍体鲫鲤的成熟卵子处于第二次减数分裂中期,精子通过受精孔进入卵内。精子入卵以来,受精孔立即被受精塞堵住。受精后8min,受精卵出现明显的精子星光,同时进入第二次减数分裂后期,即将排出第二极体;13min时,精子头部开始膨胀,趋向核化;18min时,雌雄原核均已形成,并向胚盘中央靠近;23min时,雌,雄原核开始接触;33min时,雌,雄原核完全融合成为一个合子核;38min时,受精卵开始第一次卵裂,53min后分裂形成两个子核。该研究证明异源四倍体鲫鲤和大多数二倍体鱼一样,具有正常的受精细胞学程序,受精方式为单精受精。     

生命的起点——受精

封面照片展示金鱼卵细胞受精的瞬间。精子头部钻入卵细胞的受精孔。当精子钻入后,卵细胞表面立即分泌粘稠物质,阻塞了受精孔,防止其它精子再钻入。制作过程:在雌金鱼排卵后,立即挤压雄鱼下腹部排精,混合后固定于5％戊二醛,用缓冲液冲洗、酒精脱水,醋酸异戊酯置换,在临界     

THE EFFECT OF HYDROGEN ION CONCENTRATION UPON THE INDUCTION OF POLARITY IN FUCUS EGGS : I. INCREASED HYDROGEN ION CONCENTRATION AND THE INTENSITY OF MUTUAL INDUCTIONS BY NEIGHBORING EGGS OF FUCUS FURCATUS

1. The eggs of Fucus furcatus develop perfectly in sea water acidified to pH 6.0. They are retarded at pH 5.5. At pH 5.0 they do not develop, nor do they cytolize. 2. In normal sea water in the dark at 15°C., eggs develop rhizoids on the sides in the resultant direction of a mass of neighboring eggs. The polarity and the whole developmental pattern of the embryo is thereby induced. This inductive effect does not operate, however, unless the directing mass is an appreciable aggregation of cells (10 or more), or unless there are numerous other eggs in the dish. A group of five eggs alone in a dish do not carry out mutual inductions. Two eggs alone in a dish do not develop rhizoids toward each other. 3. When the sea water is acidified to pH 6.0 all sizes of aggregations carry out mutual inductions. Two eggs alone in a dish now develop rhizoids on the sides toward each other, provided they are not more than about 4 egg diameters apart. 4. Increased hydrogen ion concentration thus augments or intensifies the mutual inductive effect. 5. This may explain why only larger masses of eggs show inductions in normal sea water, since presumably the larger masses considerably increase the hydrogen ion concentration locally. 6. The nature of the inductive action is discussed. 7. In acidified sea water at pH 6.0, compared with normal sea water at pH 7.8–8.0, the rhizoids originate and extend with a strongly increased downward component. The substrate then forces further extension or growth of the rhizoid to be in the plane of the substrate.     

A NEW SPECIES OF SERIN FROM ETHIOPIA

From Ethiopia, a new species of streaked seedeater (Serin), the Ankober Serin Serinus ankoberensis. is described. It is closely related to S. menachensis of the Arabian peninsula, and like it, is a highland species living at around 3030 m along the top of the steep escarpment of the central highland massif. It is a terrestrial species. A nest found in March contained three white eggs in a vertical hole in an overhanging bank.     

Fish-egg predation by the small clingfish <Emphasis Type="Italic">Pherallodichthys meshimaensis</Emphasis>(Gobiesocidae) on the shallow reefs of Kuchierabu-jima Island,southern Japan

Synopsis We observed predation of demersal fish eggs by the clingfish Pherallodichthys meshimaensis on the shallow reefs of Kuchierabu-jima Island, southern Japan. The processes of egg predation varied with the target species. For targeting of eggs of the combtooth blenny Istiblennius edentulus, up to 65 individuals of the clingfish gathered around the I. edentulus nest hole. Some individuals succeeded in intruding into the hole and fed on eggs while the egg-guarding male of I. edentulus temporarily left the nest. For targeting of eggs of the triplefin blenny Helcogramma obtusirostris, solitary clingfish individuals closely approached spawning females of H. obtusirostris at nests on open surfaces of rocks. Most clingfish contained only fish eggs in their diets, and these fish-egg eaters had larger body sizes than individuals that mainly fed on harpacticoid crustacea. Thus, P. meshimaensis may change its feeding habits when growing to an obligate fish-egg eater targeting demersal egg spawners.     

Formation of Sperm Entry Holes in the Vitelline Membrane of Hydroides hexagonus (Annelida) and Evidence of their Lytic Origin

Electron micrographs of inseminated eggs of Hydroides hexagonus previously had shown that in the immediate vicinity of the penetrating spermatozoön a small portion of the vitelline membrane regularly was absent, and it had been suggested that this area was a hole made by lytic activity of the individual spermatozoön during the course of its passage through the membrane. This deduction would receive support if it could be established that a sperm entry hole does form in living material. During the present study a hole repeatedly observed and photographed in the membrane of living eggs was found to arise as the spermatozoön penetrated the membrane. Gently compressed eggs formed exovates only through this hole. The holes, and exovates, were not found except at sperm entry sites. It was concluded that this hole is the counterpart of the area from which the membrane is absent in the electron micrographs cited above, and that the spermatozoön makes this hole. In an electron micrograph two spermatozoa which had penetrated the membrane at separate but closely neighboring points now occupy a single hole. It is argued that if each spermatozoön had displaced the membrane mechanically to make its hole, then there should be two holes, with a partition of membrane between them, but if each had eroded the membrane by applying lysin, a single hole should have formed as the eroded areas expanded and finally merged into one. The latter view agrees with the facts of the electron micrograph. It is concluded that lysis is the most probable means by which the individual spermatozoön makes its hole.     

日本鳗鲡精卵的超微结构以及受精过程观察

通过扫描电镜和透射电镜对经人工催产获得的日本鳗鲡(Anguilla japonica)精子、卵膜的超微结构以及受精过程进行了观察。实验观察到,除一般硬骨鱼类的精子特性外,日本鳗鲡精子有其独特的结构。精子头部为不规则的梨形,有背腹面之分。一个巨大的球形线粒体位于头部顶端。精子中段向后伸出一支根,支根位于袖套腔外精子的背侧,前端向精子头部线粒体方向延伸,支根的微管结构为"8+2"结构,并在精子入卵过程中起到切断鞭毛的作用。精子的尾部由鞭毛和鞭毛末端的结组成。鞭毛横切面呈圆形,无侧鳍,鞭毛微管结构为"9+0"结构。受精卵的整个表面密布着无规律延伸的脊、脊包围形成的窝和窝中的孔所组成的脊孔复合体,但无典型特征的受精孔。受精卵超薄切片观察发现,日本鳗鲡卵膜分为外层壳膜和内层卵黄膜。壳膜与卵黄膜间为卵周隙。壳膜只观察到放射带,未见透明带。放射带可分为三个亚层:最外层为脊孔复合体的脊,中间层为皱纹层,最内层为致密的平滑层。脊孔复合体的孔横穿整个放射带,在放射带内层形成一个乳突状结构。日本鳗鲡的卵膜不仅具有保护卵子的作用,而且还参与了受精。实验还通过扫描电镜观察了日本鳗鲡精子的入卵过程。观察结果认为:日本鳗鲡精子入卵过程可分为卵膜对精子的吸引、精子对卵膜的锚定、精核的进入和孔封闭等4个阶段。但由于研究只观察到受精过程中日本鳗鲡精子和卵膜的形态变化,因此对精子穿过卵膜的方式和特征等尚需做进一步的研究。整个受精过程为1min30s左右。此外,研究还探讨了日本鳗鲡精子结构的特殊性和受精过程的特殊性,为进一步突破日本鳗鲡人工育苗技术提供了理论依据。       

Host-marking by female pepper weevils, Anthonomus eugenii

Pepper weevils, Anthonomus eugenii Cano (Coleoptera: Curculionidae), feed and oviposit in flower buds and small fruits of plants in the genus Capsicum, as well as several species of Solanum (Solanaceae). Females chew a small hole into the fruit, deposit a single egg within the cavity, and seal the hole with a clear anal secretion that hardens into an ‘oviposition plug’. Female oviposition behavior was studied in a series of small‐arena bioassays to determine whether previous oviposition in Jalapeño pepper fruit deterred subsequent oviposition and to determine what specific cues from an infested fruit influence female behavior. In choice and no‐choice tests, females preferred clean fruit to fruit that had received four eggs 24 h previously (i.e., infested fruit), whether the fruit was infested with conspecific eggs or their own eggs. Further bioassays demonstrated that the presence of female frass, or oviposition plugs alone, in the absence of eggs or any fruit damage, was sufficient to deter oviposition. In addition, females given the choice between an infested fruit with the oviposition plug removed or an unaltered infested fruit preferred the fruit with no plugs, even when eggs, frass, and feeding damage were still present. To determine whether females would avoid infested peppers under more natural conditions, we quantified oviposition on infested and uninfested sentinel pepper fruit within individually caged plants and on clean and infested plants caged together. Females consistently laid more eggs on clean fruit than on infested fruits and moved within and among pepper plants to search for more acceptable oviposition sites. We conclude that oviposition plugs, along with contaminated female, but not male, frass contain a deterrent that, in the absence of any other cue, is enough to alert a female that a patch is occupied.     

Developmental stage of failed eggs in the red-legged partridge <Emphasis Type="Italic">Alectoris rufa</Emphasis>

Understanding whether egg failure occurs more frequently during laying or during incubation is important for determining the most vulnerable period of the egg phase in bird species with long laying and incubation periods. However, most studies compare nest failure during the egg stage and the hatchling stage. In this study we examined whether egg failure was higher during the laying period and early development than during the final stages of development in a population of red-legged partridge (Alectoris rufa) from northeast Spain. We collected 216 abandoned eggs in the field. Only 12% (n = 26) of the eggs were sufficiently intact to enable direct assessment of developmental stage, showing that 81% of 26 eggs were lost during early stages. The majority of eggs were depredated (n = 154, 71%), as evidenced by an opening hole. To take advantage of information contained in these eggs, we propose a simple method to assess their developmental stage by measuring the size of the opening of their hole. Based on this method, we estimated that the proportion of eggs lost during early stages ranged from 72 to 83%. We validated this result of a high percentage of egg failure during early developmental stages with a larger experimental sample. Nest losses in the partridge are higher during the laying period or early development. This result is important in that the direction of conservation efforts and their seasonal application should be adjusted to account for the most important factors affecting egg failure.     

USE OF BLUE LAKE AS AN INDICATOR OF BACTERIAL PENETRATION INTO EGGS

Blue Lake, an insoluble dye, was evaluated as an indicator of potential bacterial penetration into eggs. Various groups of eggs (fresh-laid; commercial; water-washed) were dipped in 0.25% (w/v) Blue Lake in 0.1% Triton X-100 solution for 2 min and incubated at room temperature up to 1 ± 24 h. Penetration was detected by counting the blue dots on shell membranes after breaking the eggs. Commercial eggs allowed the easiest penetration. All commercial eggs showed blue dots even at 2 min incubation and the average count reached 111/egg at 1 h. Water-washed eggs allowed much less penetration than commercial eggs and the counts of blue dots on those eggs were 10/egg at 2 min and 22 at 1 h. Fresh-laid eggs did not allow any penetration up to 24 h. Above results corresponded very well with the penetration study with Salmonella enteritidis and also with the morphological study of eggshell surfaces using electron microscopy where fresh-laid eggs had intact cuticle layers, but commercial eggs did not. Thus, Blue Lake dye might be used as a rapid indicator of bacterial penetration through eggshells.     

On oviposition in weevils of the genus <Emphasis Type="Italic">Larinus</Emphasis> Dej. (Coleoptera,Curculionidae)

The following actions performed by females of several Larinus Dej. species during egg laying are described: search of an appropriate place on the plant, making the hole for the egg, oviposition proper, and sealing the hole. The hole preparation takes the longest time and the greatest effort. Only one individual usually completes development in one flower head. Females of Larinus vulpes Ol. prefer larger flower heads for oviposition and occasionally lay eggs into stems. The ability of females to distinguish the flower heads with already laid eggs is discussed. Species of Larinus may be divided into two groups with “early” and “late” oviposition. The evolution of egg laying in the genus Larinus is discussed.