The sex pheromone gland of the female European corn borer moth, Ostrinia nubilalis was studied using light and electron microscopy. The pheromone gland is formed by hypertrophied epidermal cells at the mid-dorsal region of the intersegmental membrane between abdominal segments 8 and 9/10. Active glandular cells contain extensive apical membrane foldings, a single nucleus, many free ribosomes, numerous mitochondria, microtubules and lipid droplets. Smooth endoplasmic reticulum is scanty. In young moths, the glandular cells are smaller in size, the microvilli at the apical membrane are poorly developed and the cytoplasm contains fewer mitochondria, microtubules, and no lipid droplets. The surrounding unmodified epidermal cells are small cuboidal or squamous cells. These cells have ill-defined apical membrane foldings and do not contain lipid droplets in the cytoplasm and the overlying cuticle. Fatty acids analyses revealed the presence of the sex pheromone components, (E)-11-tetradecenyl acetate, and their immediate precursors, methyl (E)-11- and methyl (Z)-11-tetradecenoate, only in the dorsal portion of the cylindrical intersegmental membrane. Results of the present study show that the sex pheromone gland of O. nubilalis is restricted to the dorsal aspect of the intersegmental membrane between segments 8–9/10 and is not a ring-gland.

The quantity of male accessory gland secretory proteins in relation to the number of cells in the gland, size of the gland and the duration of copulation has been studied in seven members of the nasuta subgroup of Drosophila. The study revealed that the difference in the quantity of secretions is independent of the number of secretory cells in the gland. However, a positive correlation exists between the quantity of secretions and size of the gland; while there is no correlation between the copulation duration and the quantity of secretions. Further, there is an increase in the values of all the parameters studied, with increasing distance of the species from the ancestor.

vas RNA has been identified in germ-line cells and its precursors in zebrafish, with the result that the germ-line lineage can be traced throughout embryogenesis. In the present study, we described vas localization and the migration of vas-positive cells in goldfish, using whole mount in situ hybridization. The signals of vas mRNA localization appeared at the marginal part of the first to third cleavage planes. The eight signals were detected during the period from the 8- cells to the 512-cell stage. At the late-blastula stage, additional numbers of vas-positive cells were observed, suggesting the proliferation of these cells. At the segmentation period, vas-positive cells showed a long extended distribution along the embryonic axis, but did not form any clusters. vas-positive cells were occasionally distributed at the head region, especially around the future otic vesicle. These signals were inherited to the primordial germ cells, suggesting that vas-positive cells were primordial germ cells (PGCs) in goldfish.

Self-sterility of solitary ascidians is a typical example of the allogeneic recognition, though its molecular mechanism remains an open question. In this paper we analyze the fertility between siblings from selfed and crossed eggs to understand the genetic basis of self-sterility in the ascidian, Ciona intestinalis. First, we show that the self-sterility is strict and stable, and the individuality expressed in gametes is highly diversified in the wild population that we used. Secondly, we show one-way cross-sterility and reciprocal cross-sterility within the siblings that are self-sterile but fertile with non-siblings. Thirdly, we show self-sterility and cross-sterility share some natures and both are closely related to the sperm capacity not to bind to the vitelline coat of the autologous eggs or the eggs sterile to the sperm concerned.

In all, this paper shows that the self-sterility is genetically governed by a multiple-locus system, and that most probably individual-specific determinants are haploid expression in sperm and diploid expression in eggs, given they recognize self but not non-self.

A multisubunit protein complex called cohesin is required for the cohesion between sister chromatids in both mitosis and meiosis in yeast. We investigate here the mRNA expression patterns of mouse homologues of the yeast mitotic cohesin rad21 and the meiotic cohesin rec8 in various organs, with special attention to their expression in gonads. Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses revealed that, in contrast to the ubiquitous expression of rad21 mRNA in all of the organs examined, rec8 was expressed only in the gonads. We conducted in situ hybridization analysis to identify the cells that express rad21 and rec8 mRNAs in the gonads. In the testis, rad21 mRNA was expressed in somatic cells and spermatogonia but not in spermatocytes, and conversely, rec8 mRNA was expressed in spermatocytes but not in spermatogonia or somatic cells. Spermatids expressed rad21 and rec8 mRNAs simultaneously. In the ovary, rad21 mRNA was detected in all of the ovarian cells including germ cells and somatic cells, whereas rec8 mRNA was detected only in oocytes. Unlike the widespread expression of rad21 gene, therefore, the gene expression of rec8 is strictly confined to spermatocytes and spermatids in male mouse and oocytes in female mouse. The restricted expression pattern of rec8 mRNA implies its essential role in meiosis in both sexes of mammals, as has been reported in yeast. We also discuss the cooperative functions of Rad21 and Rec8 on the basis of the finding that their mRNAs are coexpressed in oocytes and spermatids.

To investigate the internal fertilization of the guppy Poecilia reticulata, the present electron microscopic observations were focused on the morphology of the sperm storage site in females. In the ovary of the mature female guppy, many spermatozoa were found in a synaptic knob-shaped micropocket (SSP) as the sperm storage (probably sperm entry) site on the follicle surface which was the expanded blind alley of a small tract extending from the ovarian cavity. Oocytes in the developmental stage of oil droplet formation already showed the attachment of the terminal end of the small tract opening into the ovarian cavity. The lateral wall of the tract attaching to the follicle surface consisted of epithelial cells fast jointed with tight junctions and desmosomes. The thick lateral wall of SSP was constructed with complex epithelial cell layers, and the terminal bottom was comprised of a single layer of epithelial cells on the surface of the follicular layer, which consisted of a very thin thecal cell layer, basement membrane, and granulosa cell layer. The vitellus was enclosed by the follicular layer and thin chorion, in which the micropyle was absent. In fully-grown oocytes, the germinal vesicle containing comparative short chromosomes did not always locate in the vicinity of the storage SSP of spermatozoa.

There is much information on oogenesis from the resumption of the first meiotic division to oocyte maturation in many vertebrates; however, there have been very few studies on early oogenesis from oogonial proliferation to the initiation of meiosis. In the present study, we investigated the histological changes during early oogenesis in barfin flounder (Verasper moseri). In fish with a total length (TL) of 50mm (TL 50mm fish), active oogonial proliferation was observed. In TL 60mm fish, oocytes with synaptonemal complexes were observed. Before the initiation of active oogonial proliferation, somatic cells which surrounded a few oogonial germ cells, started to proliferate to form the oogonial cysts that accompanied oogonial proliferation. In TL 70mm fish, however, the cyst structure of the oocyte was gradually broken by the invagination of somatic cells, and finally the oocyte became a single cell surrounded by follicle cells. Upon comparison of nuclear size, DNA-synthesizing germ cells could be divided into two types: small nuclear cells and large nuclear cells. Based on histological observation, we propose that the small nuclear cells were in the mitotic prophase of oogonia and the large nuclear cells were in the meiotic prophase of oocytes, and that the nuclear size increases upon the initiation of meiosis.

In Memanbetsu town, Hokkaido island, Japan, a high frequency of natural triploid loaches Misgurnus anguillicaudatus (7.4% on average) was detected by flow cytometry for relative DNA content. Among sympatric diploid females (n=6) from a single population, we found two unique females that laid unreduced diploid eggs. They gave normal diploid progeny even after induction of gynogenesis with genetically inert UV-irradiated sperm. When fertilized with normal loach sperm, some unreduced eggs developed into triploids, but the rest into diploids. Hybridization using goldfish Carassius auratus sperm gave both normal diploid loaches and inviable allotriploid hybrids possessing the diploid loach genome and the haploid goldfish genome. Microsatellite genotyping and DNA fingerprinting demonstrated that the diploid progeny developing from the unreduced eggs were genetically identical to the mother, while the triploids had some of the paternal DNA. These results indicate that the diploid eggs reproduced unisexually as a diploid clone and in other cases developed into triploids after accidental incorporation of sperm nucleus. The presence of at least one clonal line in this area was shown by the identical DNA fingerprint detected in five out of 17 diploid loaches examined.

Larvae of the bamboo borer, Omphisa fuscidentalis, enter larval diapause in September and pupate in the following June (Singtripop et al., 1999). We examined the changes in the responses of larvae to exogenous 20-hydroxyecdysone (20E) in order to estimate the progress of diapause development. In this respect, we adopted two terms, responsiveness and sensitivity of larvae to 20E. Responsiveness was estimated by the percentage of larvae that pupated, and sensitivity was evaluated by the duration from the day of 20E injection to pupation. The responsiveness of larvae declined gradually from September to November when larvae were least responsive to 20E, and then increased markedly from January to February. This indicates that the intensity of diapause increases from September to November and terminated gradually thereafter. Thus the sequence of events as the larval responses to 20E is characterized by a V-shaped curve. Sensitivity of larvae to 20E was at the same level from September to December, and increased remarkably from December to January. The abrupt increase in the sensitivity occurred one month earlier than the bottom of the V-shaped curve of larval responsiveness, suggesting that the increases in the responsiveness and sensitivity in the latter half of diapause may be brought about by respective mechanisms.

The ultrastructural differences between the inner ears of Japanese red-bellied newts (Cynops pyrrhogaster) and black-spotted pond frogs (Rana nigromaculata) were investigated. Scanning electron microscopic observations showed apparent morphological differences in the shape of the ampulla cristae and the localization of the striola in the saccular macula. There were differences in the length of the kinocilia of the sensory hairs in each sensory region. In addition, the diameters of the bundles of stereocilia differed between the two species: the bundles of stereocilia in the semicircular cristae were thicker in frogs than in newts, while those of the utricular and lagenal maculae were thicker in newts than in frogs.

Vertebrates are part of the phylum Chordata, itself part of a three-phylum group known as the deuterostomes. Despite extensive phylogenetic analysis of the deuterostome animals, several unresolved relationships remain. These include the relationship between the three deuterostome phyla (chordates, echinoderms and hemichordates), and the monophyletic or paraphyletic origin of the cyclostomes (hagfish and lampreys). Using robust Bayesian statistical analysis of 18S ribosomal DNA, mitochondrial genes and nuclear protein-coding DNA, we find strong support for a hemichordate-echinoderm clade, and for monophyly of the cyclostomes.

A comparison of allozyme variation, restriction fragment length polymorphisms in the mitochondrial DNA and partial sequences of the ND II gene (496 bp) was made among two lacustrine populations of the piscivorous chub (Opsariichthys uncirostris uncirostris) in Japan, four fluvial populations in Korea, one lacustrine population in Russia and one specimen from the Amur River (O. u. amurensis). All analyses indicate that the Japanese populations of piscivorous chub are separable from the Asian mainland populations of Korea and Russia. The latter populations were further divided into the Korean and Russian fish. Although opinions are divided on the phylogenetic position of the population in Lake Mikata, Japan, which shows unique morphological traits intermediate between those of the population in Lake Biwa and the mainland populations, the current analysis indicates a closer relationship to the population in Lake Biwa.

A new species of the peracaridan order Bochusacea, Thetispelecaris yurikago, is described from a submarine cave on Grand Cayman Island, the Caribbean Sea. The new species is the fourth species of the order and family, and the second of the genus. Recent studies have strongly suggested a close phylogenetic affinity between cave-dwelling and deep-sea taxa in the Bochusacea as recognized in other cavernicolous/deep-sea crustaceans such as amphipods and copepods. The morphology of the gut and female reproductive system is observed for the first time in the Bochusacea: the stomach is complex with structures such as ridges, processes, spinules, and hairs in the lumen; paired gonopores are located near the base of the fifth pereiopods on the sternite.