Spawning ecology of Girella punctata and G. leonina (Perciformes: Girellidae) in the coastal waters of the Izu Peninsula, Japan

The girellid fishes, Girella punctata and G. leonina, are commercially important fishes in Japan, but interspecific differences in their spawning ecology are unclear. In the present study, seasonal variations in the species composition and gonadosomatic index (GSI) were examined for G. punctata and G. leonina collected from the coastal waters of the Izu Peninsula, in order to clarify the spawning ecology of these two species. Both adults and juveniles were genetically identified by PCR-RFLP using mtDNA. The GSI of G. punctata showed markedly high values (>15.0) in April, whereas the GSI values of G. leonina were constantly low (<0.5). This result suggests that the coastal area of the Izu Peninsula is utilized as a spawning ground by G. punctata but not by G. leonina. Juveniles of G. punctata mostly appeared from May to July, whereas those of G. leonina appeared during the longer period from January to June. Juveniles of G. punctata born in the study area are inferred to settle to the sea bottom around the spawning ground after a one-month planktoninc life phase, whereas G. leonina juveniles are likely to be immigrants from another area

Spawning ecology of Girella punctata and G. leonina (Perciformes: Girellidae) in the coastal waters of the Izu Peninsula, Japan

The girellid fishes, Girella punctata and G. leonina, are commercially important fishes in Japan, but interspecific differences in their spawning ecology are unclear. In the present study, seasonal variations in the species composition and gonadosomatic index (GSI) were examined for G. punctata and G. leonina collected from the coastal waters of the Izu Peninsula, in order to clarify the spawning ecology of these two species. Both adults and juveniles were genetically identified by PCR-RFLP using mtDNA. The GSI of G. punctata showed markedly high values (>15.0) in April, whereas the GSI values of G. leonina were constantly low (<0.5). This result suggests that the coastal area of the Izu Peninsula is utilized as a spawning ground by G. punctata but not by G. leonina. Juveniles of G. punctata mostly appeared from May to July, whereas those of G. leonina appeared during the longer period from January to June. Juveniles of G. punctata born in the study area are inferred to settle to the sea bottom around the spawning ground after a one-month planktoninc life phase, whereas G. leonina juveniles are likely to be immigrants from another area

Sexual maturation of Girella punctata and G. leonina (Perciformes: Girellidae) in the neritic sea off the Pacific coast of Japan

The spawning ecology of the girellid fishes in Japanese waters has been reported almost only for Girella punctata, whereas little is known about Girella leonina. We examined sexual maturation of G. punctata and G. leonina collected from the coastal waters (neritic) of the Izu Peninsula and Tanegashima Island, based on gonadosomatic index (GSI) and gametogenesis, in order to clarify interspecific differences in spawning ecology. The GSI values of G. punctata in the Tanegashima Island region were markedly high in March, a month prior to the peak in April in the Izu Peninsula region. Girella punctata with elevated GSI had histologically mature ovaries and testes in spring in the both regions, suggesting spawning at this time of year. In contrast, the GSI values of G. leonina were much lower in the both regions, but the maximum GSI of both male and female G. leonina were slightly higher in the Tanegashima Island region than in the Izu Peninsula region. Furthermore, oogenesis in G. leonina was more advanced in the Tanegashima Island region. It is thus probable that Tanegashima Island is relatively near the spawning ground of G. leonina

Species composition of the genus <i>Scombrops</i> (Teleostei, Scombropidae) in the waters around the Japanese Archipelago: detection of a cryptic species

<p>Current literature states that family Scombropidae consists of a single genus <i>Scombrops</i> comprising three species worldwide, with two of them, <i>Scombrops boops</i> and <i>Scombrops gilberti</i>, distributed in the waters around the Japanese Archipelago. Although these two scombropids are commercially important species, little is known about the ecology of these fishes. It is difficult to discriminate between these two species based on external characteristics because of their morphological similarity. Here, we report two different morphotypes characterized by the relative growth between the otolith size and the standard length (SL) of the scombropid specimens caught in southern waters off Kyushu Island, Japan, and show the genetic relationship between the morphotypes by means of phylogenetic analyses using complete DNA sequences of the cytochrome <i>b</i> gene. The relationship between otolith weight and SL was significantly different between specimens < 505 mm SL and those > 550 mm SL. Phylogenetic analysis demonstrated that the sequences from these scombropid specimens formed three clades: two corresponded to <i>S. boops</i> and <i>S. gilberti</i>, while the third did not correspond to any sequence recorded in databases, suggesting that these specimens are undescribed scombropid species. Almost all the specimens with SL < 505 mm (<i>n</i> = 76) were identified as <i>S. boops</i>, and only nine as <i>S. gilberti</i>. On the other hand, almost all the specimens with SL > 550 mm (<i>n</i> = 41) fell in the unidentified group except for four specimens, whose sequences were identical to that of <i>S. boops</i>.</p

Diversification of transcriptional modulation: Large-scale identification and characterization of putative alternative promoters of human genes

By analyzing 1,780,295 5′-end sequences of human full-length cDNAs derived from 164 kinds of oligo-cap cDNA libraries, we identified 269,774 independent positions of transcriptional start sites (TSSs) for 14,628 human RefSeq genes. These TSSs were clustered into 30,964 clusters that were separated from each other by more than 500 bp and thus are very likely to constitute mutually distinct alternative promoters. To our surprise, at least 7674 (52%) human RefSeq genes were subject to regulation by putative alternative promoters (PAPs). On average, there were 3.1 PAPs per gene, with the composition of one CpG-island-containing promoter per 2.6 CpG-less promoters. In 17% of the PAP-containing loci, tissue-specific use of the PAPs was observed. The richest tissue sources of the tissue-specific PAPs were testis and brain. It was also intriguing that the PAP-containing promoters were enriched in the genes encoding signal transduction-related proteins and were rarer in the genes encoding extracellular proteins, possibly reflecting the varied functional requirement for and the restricted expression of those categories of genes, respectively. The patterns of the first exons were highly diverse as well. On average, there were 7.7 different splicing types of first exons per locus partly produced by the PAPs, suggesting that a wide variety of transcripts can be achieved by this mechanism. Our findings suggest that use of alternate promoters and consequent alternative use of first exons should play a pivotal role in generating the complexity required for the highly elaborated molecular systems in humans