Embryogenesis in the reef building corals Acropora intermedia, A. solitaryensis, A. hyacinthus, A. digitifera, and A. tenuis was studied in detail at the morphological level, and the relationships among the animal pole, blastopore, and mouth were investigated for the first time in corals. These species showed essentially the same sequence of development. The embryo undergoes spiral-like holoblastic cleavage despite the presence of a dense isolecithal yolk. After the morula stage, the embryo enters the “prawn-chip” stage, which consists of an irregularly shaped cellular bilayer. The embryo begins to roll inward to form the bowl stage; the round shape observed during this stage suggests that it may be the beginning of gastrulation. However, the blastopore closes and the stomodeum (mouth and pharynx) is formed via invagination at a site near the closed blastopore. During the planula stage, a concavity forms in the aboral region in conjunction with numerous spirocysts, suggesting that spirocysts are used to attach to the substrate before the onset of metamorphosis.

Mitochondrial DNA variation in the cytochrome b (cyt b) gene and the control region was examined in the red fox Vulpes vulpes from Japan, with special focus on the population divergence between Hokkaido and northern Honshu. Resultant haplotypes from Hokkaido were subdivided into two distinct groups (I and II), with an average genetic distance of 0.027 for cyt b. Divergence time is roughly estimated to be 1–2 million years ago, given that the conventional divergence rate of the mammalian cyt b gene is 2% per million years. Notably, Group II was only found in Hokkaido, whereas Group I comprised haplotypes from Honshu, Kyushu (Japan), eastern Russia, and Europe, as indicated by a comparison of our own data to the literature. On the other hand, judging from constructed trees, Group I haplotypes from Hokkaido appeared to differ from those from other parts of Japan, i.e., Honshu and Kyushu. This implies that Blakiston's Line, which demarcates the boundary between Hokkaido and Honshu, has been an effective barrier and has allowed the structuring of genetic variation in maternal lineages. Thus, these results suggest that the Hokkaido population, which is sometimes referred to as the distinct subspecies V. v. schrencki, has its own genetic background with multiple migration events and differs from the parapatric subspecies V. v. japonica found in Honshu and Kyushu.

We studied by SEM the external morphology of the ooecium in eight bryozoans of the genus Cauloramphus Norman, 1903 (Cheilostomata, Calloporidae): C. spinifer, C. variegatus, C. magnus, C. multiavicularia, C. tortilis, C. cryptoarmatus, C. niger, and C. multispinosus, and by sectioning and light microscopy the anatomy of the brooding apparatus of C. spinifer, C. cryptoarmatus, and C. niger. These species all have a brood sac, formed by invagination of the non-calcified distal body wall of the maternal zooid, located in the distal half of the maternal (egg-producing) autozooid, and a vestigial, maternally budded kenozooidal ooecium. The brood sac comprises a main chamber and a long passage (neck) opening externally independently of the introvert. The non-calcified portion of the maternal distal wall between the neck and tip of the zooidal operculum is involved in closing and opening the brood sac, and contains both musculature and a reduced sclerite that suggest homology with the ooecial vesicle of a hyperstomial ovicell. We interpret the brooding apparatus in Cauloramphus as a highly modified form of cheilostome hyperstomial ovicell, as both types share 1) a brood chamber bounded by 2) the ooecium and 3) a component of the distal wall of the maternal zooid. We discuss Cauloramphus as a hypothetical penultimate stage in ovicell reduction in calloporid bryozoans. We suggest that the internal-brooding genus Gontarella, of uncertain taxonomic affinities, is actually a calloporid and represents the ultimate stage in which no trace of the ooecium remains. Internal brooding apparently evolved several times independently within the Calloporidae.

In order to elucidate the taxonomic status of the Fejervarya limnocharis complex relative to Malaysia and Japan populations, morphological observations and molecular phylogenetic analysis were carried out using three populations from Indonesia (type locality), Malaysia, and Japan. In addition, we conducted histological and spermatogenic observations using hybrids among these populations. Principal component and cluster analyses demonstrated that these populations could be clearly separated from one another. Abnormal testes were found in the hybrids between the Japan and Indonesia populations and between the Japan and Malaysia populations, but testes of the controls and hybrids between the Malaysia and Indonesia populations were quite normal. The mean number of univalents per cell was 5.42, 4.58, and 0.20 in hybrids between the Indonesia and Japan populations, Malaysia and Japan populations, and Indonesia and Malaysia populations, respectively. Sequence divergences in 16S rRNA and Cyt b genes were 0–0.4% (x̄=0.2%) and 0.3–1.5% (x̄=1.0%), respectively, between the Malaysia and Indonesia populations, and 2.4–2.6% (x̄=2.5%) and 11.0–12.0% (x̄=11.5%) between the Japan population and F. limnocharis complex, including the Malaysia and Indonesia populations and F. multistriata from China. This study indicated that the Malaysia population and F. multistriata from China should be designated as a subspecies of topotypic F. limnocharis, and that the Japan population should be regarded as a distinct species.

The ecological characteristics of 597 yellow and silver-stage Japanese eels, Anguilla japonica, were examined and compared among collection sites located at three different latitudes of Japan (Amakusa Islands, Mikawa Bay, and Sanriku Coast) to provide basic data on this unusual catadromous fish species. Eels were sexed and their total length, body weight, age, and growth rate based on otolith analysis was compared among sexes, stages, and collection sites. The overall sex ratio favored females (94%), but the sex ratio differed among the three locations. The frequency of females was highest in the coastal waters at Sanriku in the north (100%), next highest at Mikawa Bay in central Japan (95%), and lowest in the Amakusa Islands in the south (70%). Silver eel males ranged from 41.2–66.3 cm in length and 4–10 years in age, and silver eel females from 44.3–97.2 cm in length and 5–17 years in age. Female eels generally grew faster (8.7±2.2 cm/year) than males (6.4±2.6 cm/year), and the growth rate slowed in the older eels. The growth rate of A. japonica at all three sites was much faster than that of other temperate anguillid species (<4 cm/year), and their age at maturation was younger than that of other temperate species (~7 to >50 years), suggesting this species has important ecological differences from other similar species.

Since the gene expression of guanylin peptides and their receptors, guanylyl cyclase Cs, is enhanced in the intestine of seawater (SW)-adapted eels compared with fresh water (FW)-adapted fish, the guanylin family may play an important role in SW adaptation in eels. The present study analyzed the effect of three homologous guanylin peptides, guanylin, uroguanylin and renoguanylin, on ion movement through the eel intestine, and examined the target of guanylin action using Ussing chambers. The middle and posterior parts of the intestine, where water and ion absorption occurs actively in SW eels, exhibited serosa-negative transepithelial potential, while the anterior intestine was serosa-positive. Mucosal application of each guanylin in the middle or posterior intestine reduced the short-circuit current (I_sc) dose dependently and reversed it at high doses, and reduced electric tissue resistance. The effects were greater in the middle intestine than in the posterior intestine. All three guanylins showed similar potency in the middle segment, but guanylin was more potent in the posterior segment. 8-bromo cGMP mimicked the effect of guanylins. The intestinal response to guanylin was smaller in FW eels. The mucosal presence of NPPB utilized as a CFTR blocker, but not of other inhibitors of the channels/transporters localized on the luminal surface in SW fish intestine, inhibited the guanylin-induced decrease in I_sc. In eels, therefore, the guanylin family may be involved in osmoregulation by the intestine by binding to the receptors and activating CFTR-like channels on the mucosal side through cGMP production, perhaps resulting in Cl⁻ and HCO₃⁻ secretion into the lumen.

A serious disease of the ascidian Halocynthia roretzi has been spread extensively among Korean aquaculture sites. To reveal the cause of the disease and establish a monitoring system for it, we constructed a cDNA microarray spotted with 2,688 cDNAs derived from H. roretzi hemocyte cDNA libraries to detect genes differentially expressed in hemocytes between diseased and non-diseased ascidians. We detected 21 genes showing increased expression and 16 genes showing decreased expression in hemocytes from diseased ascidians compared with those from non-diseased ascidians. RT-PCR analyses confirmed that the expression levels of genes encoding astacin, lysozyme, ribosomal protein PO, and ubiquitin-ribosomal protein L40e fusion protein were increased in hemocytes from diseased ascidians, while those of genes encoding HSP40, HSP70, fibronectin, carboxypeptidase and lactate dehydrogenase were decreased. These genes were expressed not only in hemocytes but also in various other tissues in ascidians. Furthermore, the expression of glutathione-S transferase omega, which is known to be up-regulated in H. roretzi hemocytes during inflammatory responses, was strongly increased in hemocytes from diseased ascidians. These gene expression profiles suggest that immune and inflammatory reactions occur in the hemocytes of diseased ascidians. These genes will be good markers for detecting and monitoring this disease of ascidians in Korean aquaculture sites.

Convolutriloba longifissura is a red flatworm with white dots that harbors unicellular green algae within its body. The red pigment of the flatworm that is present in round cells is soluble in ethanol or acetone, whereas the white pigment contained in the crystalline (retractile) platelets of amoeboid-shaped cells is soluble in 1% NH₄OH. These two types of pigment cells form the body coloration and are probably involved in light protection of the algal symbionts, as many algal cells are distributed beneath the body wall and some are in the highly vacuolated parenchyma. The ultrastructural features of these cells suggest a close relationship with Tetraselmis spp. The morphology of sagittocysts within the mantle is also described by means of scanning and transmission electron microscopy.

Calcium release from intracellular stores has various actions in neurons, but its effects on network oscillation have not been well understood. The olfactory center (procerebrum, PC) of the terrestrial slug Limax valentianus shows a regular oscillation in the local field potential (LFP). Here we report that caffeine, which is an agonist for ryanodine receptors and triggers calcium release from intra-cellular stores, has strong modulatory effects on the PC. In isolated PC neurons, caffeine enhanced the cytoplasmic calcium concentration, and this was blocked by ryanodine. Caffeine elevated the frequency and amplitude of the LFP oscillation, which was also blocked by ryanodine. The time lag between the frequency and amplitude effects suggests distinct mechanisms for the modulation of these two parameters. These results suggest that calcium release from intracellular stores through ryanodine receptors activates network activity in the PC.

Like other Lepidoptera, the silkworm (Bombyx mori) has both nucleated eupyrene and anucleated apyrene sperm that are derived from the same spermatocysts. The former type is responsible for egg fertilization, while the function of the latter is still uncertain. Many hypotheses have been presented concerning the role of the apyrene sperm in mating and fertilization, but none is supported by a convincing experimental approach. The aim of the present study was to enhance the production of apyrene sperm in vitro by using different concentrations of fetal bovine serum (FBS), namely 20%, 30% and 40%, in the culture medium used for cultivating the naked spermatocysts isolated from the silkworm testes at 0 hr, 120 hr, and 192~360 hr after the fourth molt. Cultivation of 0-hr spermatocysts was not successful. The development of spermatocysts into eupyrene and apyrene sperm bundles was slightly slower in vitro than in vivo. The overall growth percentage of both eupyrene and apyrene bundles was satisfactory when the spermatocysts were cultivated in TC-100 culture medium containing 30% FBS.

Guppy sperm are immotile in the fluid (seminal plasma) of the vas deferens. We previously reported that the initiation of sperm motility is regulated by “Hofmeister solutes” in the isotonic medium. This indicates that chaotropes in solution activate the guppy sperm, whereas counteracting kosmotropes negate this activational effect and keep the sperm immotile. Here we show that seminal plasma has a strong inhibitory effect on sperm activation in response to chaotropes and multivalent ions, and that this inhibitory effect is due to kosmotropicity of the seminal plasma. These findings suggest a novel system of regulation of sperm motility in the guppy, a viviparious fish, in which the sperm are kept immotile in the vas deferens by a physicochemical effect (the Hofmeister effect) of the seminal plasma.

Gnathia limicola sp. nov. is described from Okinawajima Island, Ryukyu Archipelago, southwestern Japan. Burrows of this species were found in a small intertidal creek bank on a muddy tidal flat near mangrove trees. Adult males differ from those of other Gnathia species in the following features: (1) fine setae cover peduncle articles 1 and 2 of antenna 1, peduncle articles 1–3 of antenna 2, and the erisma of the mandibles; (2) the ventral frontal border of the cephalon is medianly notched, and the lateral parts extend beyond the dorsal frontal border; and (3) the penes are fused into a thin rectangular blade directed posteriorly. Adult females and praniza larvae were also distinguished morphologically from other Gnathia species. Based on field and laboratory observations, the mating behavior of this species appears similar to that of Paragnathia formica (Hesse, 1862), which inhabits salt marshes in Europe and North Africa.

The morphology and development of a new species of the genus Balanoglossus belonging to the family Ptychoderidae are described in detail. This acorn worm was collected from the sandy seashore in the cove near Shimoda Marine Research Center, University of Tsukuba (Shimoda, Shizuoka Prefecture, Japan). This acorn worm is easily distinguished from other balanoglossids by a characteristic hepatic region. There are two kinds of hepatic saccules: large, dark-colored saccules in the anterior region and small, light-colored saccules in the posterior region. Between the two subregions of the hepatic region, there is a small region that has no or tiny saccules. This species does not form distinct burrows or mounds of casts. The breeding season is in winter. The process of embryogenesis from fertilization to metamorphosis was observed. A shift in seawater temperature from about 13°C to about 9°C induced gamete release. Two days after fertilization, embryos hatched and became typical feeding tornaria larvae. Two months after fertilization these larvae metamorphosed into juveniles and began their benthic life.

We describe Tischeria gouaniae sp. n. from the tropical forests of Belize. The new species is a leaf-miner of Gouania polygama (Rhamnaceae). Together with the related T. bifurcata Braun, it is among the most striking representatives of Tischeria. Both species possess a pseudognathos and very broad aedeagus fused with extremely long lateral processes of the juxta. The new species differs from T. bifurcata in the broadly rounded vinculum, spiny juxta, and slender apical processes of the aedeagus, and in its host plant. The external features and male genitalia of Tischeria gouaniae sp. n. are figured and described. A checklist and distribution map for all nine currently known Tischeria species from North and South America are given. Most American species are known from USA, but others are now known from tropical forest habitats of Central America, the Caribbean, and Guyana. Host-plants are known for five of the nine species reviewed here, belonging to four genera and two plant families (Fagaceae and Rhamnaceae).