Photoreceptive organs in larvae of Spionidae (Annelida) and Sipuncula

A pair of spherical unpigmented ocelli in addition to pigmented eyes have been observed in the anterior part of the prostomium in larvae of more than 40 species of Spionidae examined alive with light microscopy. Ocelli become visible in larvae at the one- to three-segment stage, increase in size as growth proceeds, and probably disintegrate in the course of metamorphosis because they were not observed in adults and settled juveniles. One pair of transparent, spherical bodies is also found in the anterior part of the head of planktotrophic pelagosphera larvae of Sipuncula. These bodies are in a similar position and have a similar appearance and size to unpigmented ocelli in Spionidae larvae. A pair of epidermal invaginations, densely covered with short cilia, is also observed antero-laterally in the head in pelagospheras of one species. These invaginations appear similar to the nuchal organs present in many polychaete larvae. Photoreceptive organs so far reported for sipunculan larvae comprise only pigmented eyes. Unpigmented ocelli and nuchal organs have never been reported in pelagospheras. Further ultrastructural investigations on sipunculan larvae are encouraged to clarify the composition, function and morphogenesis of transparent, spherical bodies and ciliated invaginations in the anterior part of the head. Such investigations may help to better understand the nature of photoreceptive structures and nuchal organs in Sipuncula, and also contribute to phylogenetic hypotheses regarding relationships of the Sipuncula and Annelida.     

波氏吻鰕虎鱼的胚胎发育

对波氏吻鰕虎鱼的胚胎发育进行了观察,详细描述了发育各期的形态特征和时序.在水温23.7～26.1 ℃条件下,受精卵历时59 h 28 min 孵出,所需积温为1480.7℃.胚胎发育可划分为6个阶段,33个发育时期.孵化率约50%.初孵仔鱼平均全长3.61 mm.     

Fine structure of the pharyngeal apparatus of the pelagosphera larva in Phascolosoma agassizii (Sipuncula) and its phylogenetic significance

Sipuncula is a small taxon of worm-like marine organisms of still uncertain phylogenetic position. Sipunculans are characterized by an unsegmented body composed of a trunk into which the anterior part, the introvert, can be withdrawn. The group has been placed at various positions within Metazoa; currently, it is either seen as sister group of a clade comprising Mollusca and Annelida or as sister to each of these. An in-group position in either Mollusca or Annelida has usually been precluded till now due to the lack of so-called annelid or molluscan “key-characters” such as segmentation and chaetae or the radula. In the development of certain taxa the trochophore stage is followed by a planktonic larva, the pelagosphera, which might exhibit phylogenetically important structures. Among these is the buccal organ, which has been considered homologous either to the ventral pharyngeal organ present in many sedentary polychaetes or to the radular apparatus of molluscs. In the present paper, the ventral pharynx of the pelagosphera larva of Phascolosoma agassizii is investigated by transmission electron microscopy. The pharynx comprises dorsolateral ciliary folds, a muscle bulb formed by transverse muscle fibres with large intercellular spaces, and an investing muscle. A tongue-like organ is lacking. These results show great structural correspondences to the ventral pharynx of polychaetes, especially to that of the flabelligerid Diplocirrus longisetosus. In contrast, there are no signs of structural similarities to the corresponding structures of molluscs. Thus evidence increases that Sipuncula are closely related to annelids; moreover, an in-group position of Sipuncula within Annelida, as suggested by recent molecular studies, is not precluded by the present data. Instead these studies find additional support. Hence the lack of segmentation and chitinous chaetae in Sipuncula would be a secondary rather than a primary situation, as has recently been shown for Echiura and Pogonophora.     

Embryonic Development of the Phoronid Phoronis ijimai

We studied the embryonic development of the phoronid Phoronis ijimai Oka, 1897. The egg cleavage is radial. The fourth and fifth cleavage furrows extend along the meridian of the egg. The blastula is flattened. Gastrulation occurs by a combination of epiboly, bending, and invagination. The mesoderm originates from two sources. The anterior mesoderm arises through immigration and gives rise to the first and second coeloms. The third coelomic mesoderm originates enterocoelically from the hindgut. The newly hatched larva has preoral and postoral ciliary bands, which can be compared with the corresponding ciliary bands of dipleurula and with the prototroch and metatroch of trochophore larvae.     

An examination of the Phascolosotna subgenera Antillesoma, Rueppellisoma and Satonus (Sipuncula)

Three of the subgenera in the sipunculan genus Phascolosoma are reviewed, based on examination of type material. The presumed difference between the subgenera Antillesoma and Rueppellisoma (number of retractor muscles) is shown to be invalid and the taxa are therefore synonymous. The 15 species are either considered junior synonyms of P. antillarum (eight), transferred to other species or genera (six), or considered incertae sedis (one). Phascolosoma antillarum is redescribed. Of the eight species in the subgenus Satonus, only P. pectinatum remains valid: the others are considered either to belong to other taxa (four) or to be incertae sedis (three).     

南方大口鲇幼鱼发育的初步研究

南方大口鲇的人工孵化鱼苗在11日龄时卵黄消失,转入营外生性营养的仔鱼阶段;23—26日龄仔鱼的主要外部器官分化完毕,转入稚鱼阶段;40—43日龄稚鱼除存在第二下颌须外,其余外形特征与成鱼相似,稚鱼阶段结束. 5月上旬在嘉陵江中采获到的当年幼鱼已发育到稚鱼阶段结束时期的水平;6—7月的当年幼鱼,当体长为151—177毫米时,第二下颌须消失.当年幼鱼体重和体长的关系为: W=e-10.87062L2.74257(N=77,r=0.9952)根据尾形、体色和须的数量的差异,可以区别南方大口鲇和鲇的当年幼鱼.     

星虫动物门活性物质及药理作用研究

本文简要介绍了星虫动物门的由来、分类和星虫的一般生理生态活性特征,并对星虫动物门的资源利用现状进行了分析,肯定了我国在星虫人工养殖、新药开发和利用其作为污染物监测方面所取得的成就.重点介绍了星虫动物门已经发现的营养活性物质、自身生理活性物质和药理活性物质以及星虫所具有的药理活性并对其未来研究进行了展望,比较了国内外学者对星虫研究的区别,为更好地保护和研究星虫提出了一些思路.     

管氏肿腿蜂的胚胎发育观察

管氏肿腿蜂Scleroderma guani Xiao et Wu的卵在24℃和RH60%~70%条件下发育约140h孵化。根据胚胎外形的发育特点,可将整个发育过程可分5个阶段:早期发育阶段、胚胎伸长期、原躯原头分化阶段、器官形成阶段和胚胎成熟期。胚层形成趋于简单化,未形成解剖学上比较完整的呼吸、排泄及循环等系统。口道形成后,胚胎体积逐渐增加,这表明胚胎在发育过程中吸收了寄主的营养物质。     

Induction of developmental abnormalities in larval goldfish, Carassius auratus L., under cool incubation conditions

Compared with incubation at a constant 22° C, exposure of goldfish embryos and larvae to 13° C, under a variety of thermal protocols, caused increased frequencies of abnormal development and, in some cases, reduced survival to hatching. The low-temperature incubation conditions were particularly deleterious when eggs were incubated at 13° C from the outset, regardless of the temperature at which the donor female ovulated and the eggs were fertilized. Significantly higher frequencies of developmental abnormalities were also noted when embryos were transferred from 22°C to 13°C at 6, 24, 128 and, in one case, 175 h after fertilization. In three of five experiments, subjecting embryos and larvae to diel fluctuations between 22 and 13° C, with a 5-h hold at the lower temperature, caused an increase in development abnormalities. These results demonstrate that the thermal requirements of goldfish embryos and larvae necessitate a delay in ovulation and spawning until water is sufficiently warm. Developmental abnormalities can be induced by exposure to cool (13° C) conditions, at least up to the time that swimbladder inflation occurs.     

SUMO化修饰系统在哺乳动物胚胎发育及器官发生中的作用

小分子泛素相关修饰物蛋白（small ubiquitin-related modifier protein,SUMO）化修饰是一种广泛存在的蛋白质翻译后修饰形式,存在于动物多个生理和病理过程中,并涉及复杂的信号通路调节过程,是细胞对应激反应的重要调节机制,并且越来越多的研究表明,SUMO化修饰在哺乳动物胚胎发育及器官发生过程中发挥重要作用。在胎儿发育过程中,SUMO化对于器官的形成及发育起着至关重要的作用。SUMO化途径的各组成成分（UBC9、SUMO1～3、PIAS、SENP1～7）在胚胎发育过程中协调胚泡与子宫间的对话、心脏发育以及颅面发育中都发挥着重要作用。在发育过程中SUMO化修饰一旦失调,则可能导致胚胎植入前缺陷、胚胎发育缺陷以及胚胎致死。本综述总结了SUMO化修饰的分子机制,以及SUMO化途径各个组成成分（SUMO、UBC9、PIAS、SENPs）在早期胚胎发育及后续器官发生中功能的最新进展,以望为后续的研究提供借鉴。