Kiyoshi Fujita

Elevated serum vitellogenin levels and gonadal abnormalities in wild male flounder (Pleuronectes yokohamae) from Tokyo Bay, Japan

Concentrations of vitellogenin (VTG) in serum of wild male flounder (Pleuronectes yokohamae) were investigated, as a biomarker for environmental estrogens in marine waters, from January 1997 to May 1998 in Tokyo Bay, Japan (n = 130) and from a reference site in Hokkaido, Japan, far from urban areas (about 40 km from Hakodate city) from March 1997 to June 1998 (n = 62). Statistically higher concentrations of serum VTG were detected in wild male flounder collected in Tokyo Bay (range: 25-2200 ng ml-1) compared to fish from Hokkaido (range: 31-91 ng ml-1) throughout the entire sampling period. Three out of 20 males collected off Haneda, in the inner part of Tokyo Bay, showed testes containing small numbers of oocytes. This intersex condition was not found among males collected from the reference site. This study suggests that the abnormally high levels of VTG and the presence of oocytes in the testis of male flounder collected from Tokyo Bay could be the effect of environmental estrogens.

Caudal skeleton ontogeny in the adrianichthyid fish,Oryzias latipes

and first and second hypurals, respectively), long neural and hemal spines of the second preural centrum, an extra caudal ossicle, an interhemal spine cartilage of the third preural centrum (CIHPU3), and 9 branched caudal rays (4 in the upper and 5 in the lower lobes). The upper hypural plate is autogenous, and the lower plate is fused with the urostyle at the proximal base. At 4.0mm NL (Fig. 1A) (immediately after hatching, 12 days after fertilization), one cartilaginous parhypural (PH) and two hypural plates had already formed beneath the posterior portion of the notochord, which had just started flexing. The lower hypural plate consisting of the first and second hypurals (HY1+2) was the largest of these three elements. One caudal ray extended from below the posterior part of the lower hypural plate and another one from the upper hypural plate (HY3+). At 4.5mm NL (Fig. 1B), a cartilaginous bud of the hemal arch of the second preural centrum (HAPU2) was recognizable in front of the parhypural and a very small, cartilaginous second epural (EP2) above the notochord. Two caudal rays could be seen at the posterior ends of each of the two hypural plates. At 4.8mm NL (Fig. 1C), the notochord flexion was more pronounced, the preural centra (PU3 and anterior ones) with their associated arches had formed and ossified, and the neural arch of the future second preural centrum (NAPU2) had appeared and begun to ossify. The parhypural became free of the notochord and a single caudal ray extended from it. There were three new rays each extending from the upper and lower hypural plates. At 5.2mm NL (Fig. 1D), the ossified first preural centrum plus first ural centrum (PU1+U1) and second preural centrum (PU2) had formed, and the lower hypural plate (HY1+2) was fused with PU1 +U1. There were four rays in the upper lobe of the caudal fin and five in the lower. At 5.5mm SL (Fig. 1E), the second ural centrum (U2) had formed from the notochord, anterior to the upper hypural plate. A small, free, cartilaginous first epural (EP1) formed anterior to the second epural. The middle part of the parhypural and the proximal part of the hypural plates began to ossify. The neural and hemal arches of the preural centra from PU2 anteriorly had fused at the dorsal and ventral medial planes respectively, and the neural and hemal spines were observable. At 6.4mm SL (Fig. 1F), all components of the caudal skeleton were larger than at the previous

Early morphological development ofOmobranchus fasciolatoceps andO. Punctatus (Blenniidae: Omobranchini) reared in an aquarium

Larval and juvenile development of two blenniids,Omobranchus fasciolatocepts andO. punctatus, is described using eggs collected from natural waters in Tokyo Bay and incubated in an aquarium. These larvae and juveniles are compared with those of two otherOmobranchus species,O. elegans andO. loxozonus, distributed widely in Japan.Onobranchus punctatus is characterized by a unique, pointed snout in preflexion larvae, no melanophores proximally on the lower part of the pectoral fins in flexion and postflexion larvae, and pterygiophores projecting externally as blades between the dorsal and anal fin-rays in postflexion larvae and juveniles.Omobranchus fasciolatoceps has the following characteristics: a few melanophores on the fore-and mid-brain, but none on the hind-brain in preflexion larvae; no melanophores on the cleithral symphysis in flexion and postflexion larvae; no external pterygiophore blades in postflexion larvae and juveniles; and a unique dorsal skin flap on the head in juveniles. Ontogenetic developement of dorsal and anal pterygiophores is described forO. fasciolatoceps andO. punctatus. InO. punctatus, the postero-distal part of each proximal radial projects remarkably to form the external blades between the soft fin-rays, whereas the external blades between the fin spines are formed by fusion of a dermal bone developed from the antero-distal part of each proximal radial with the adjacent distal radial.

Development of the caudal skeleton in the tetraodontid fish,Takifugu niphobles

The osteology of tetraodontid fishes has already been studied by many authors, e.g. Gregory (1933), Kuronuma (1943), Abe (1952a, b), and Tyler (1970, 1980), for the purposes of classification and understanding of phylogenetic relationships. However, developmental osteology as such, was not covered in these papers. Components of the caudal skeleton of adult tetraodontid fishes show a high degree of fusion (Tyler, 1980; Fujita, 1990). Ontogenic studies of the caudal skeleton will facilitate identification of osteological structures of the fused bones. The purpose of this study is to describe the osteological development of the caudal skeleton of the tetraodontid, Takifugu niphobles, and to clarify the ontogeny of the caudal skeleton.

Two series of parapophyses in neoscopelid fishes (teleostei: Myctophiformes)

Observations of the vertebrae of three genera and five species of neoscopelid fishes revealed the presence of two series of parapophyses (a ventral series and a lateral foveal series). The ventral parapophyses, situated on the ventral surface of the centra, were present on only the anterior abdominal vertebrae (AV): inScopelengys (AV1, 2),Neoscopelus (AV1–6 or 7),Solivomer (AV1–8). Parapophyses on the first vertebra were ossified, cone-shaped enlargements, the remainder being small, cartilaginous and ovalshaped. The lateral foveal parapophyses were formed from an extension of the lower edges of the foveae on the lateral surfaces of the centra, into which the ribs are set, being developed caudally to form the hemal arches: inScopelengys (AV4 posteriorly),Neoscopelus (AV6 or 7 posteriorly),Solivomer (AV8 posteriorly). The last ventral cartilaginous parapophyses and first lateral foveal parapophyses were present on the same centrum in two genera,Neoscopelus (AV6 or 7) andSolivomer (AV8). Lateral foveal parapophyses series were also found in some acanthomorphs and a ventral parapophyses series in some non-acanthomorphs. Whereas the ventral papapophyses in the non-acanthomorphs developed posteriorly to form the hemal arches, this parapophyses series in neoscopelids is incomplete, being absent on the posterior abdominal vertebrae. This suggests that the ventral parapophyses series in neoscopelids seems to be a remnant of that in the non-acanthomorphs. In myctophids, although cartilaginous ventral parapophyses were absent posteriorly from the second vertebra, enlarged ossified cone-shaped parapophyses on the first vertebra (as in neoscopelids) and lateral foveal parapophyses usually from the third vertebra were present. Accordingly, myctophids appear to be similar to neoscopelids in having two types of parapophyses.