Changes in gene expression and cellular localization of insulin-like growth factors 1 and 2 in the ovaries during ovary development of the yellowtail, Seriola quinqueradiata.

A method of controlling the somatic growth and reproduction of yellowtail fish (Seriola quinqueradiata) is needed in order to establish methods for the efficient aquaculture production of the species. However, little information about the hormonal interactions between somatic growth and reproduction is available for marine teleosts. There is accumulating evidence that insulin-like growth factor (IGF), a major hormone related somatic growth, plays an important role in fish reproduction. As the first step toward understanding the physiological role of IGF in the development of yellowtail ovaries, we characterized the expression and cellular localization of IGF-1 and IGF-2 in the ovary during development. We histologically classified the maturity of two-year-old females with ovaries at various developmental stages into the perinucleolar (Pn), yolk vesicle (Yv), primary yolk (Py), secondary yolk and tertiary yolk (Ty) stages, according to the most advanced type of oocyte present. The IGF-1 gene expression showed constitutively high levels at the different developmental stages, although IGF-1 mRNA levels tended to increase from the Py to the Ty stage with vitellogenesis, reaching maximum levels during the Ty stage. The IGF-2 mRNA levels increased as ovarian development advanced. Using immunohistochemistry methods, immunoreactive IGF-1 was mainly detected in the theca cells of ovarian follicles during late secondary oocyte growth, and in part of the granulosa cells of Ty stage oocytes. IGF-2 immunoreactivity was observed in all granulosa cells in layer in Ty stage oocytes. These results indicate that follicular IGFs may be involved in yellowtail reproduction via autocrine/paracrine mechanisms.

Characteristics of lipid and fatty acid of marine gastropod Turbo cornutus: high levels of arachidonic and n-3 docosapentaenoic acid.

Phosphatidylethanolamine and phosphatidylcholine were major components in the foot lipids of the turban shell Turbo cornutus, while triacylglycerol was the major one in its viscera, which demonstrate the high level of lipid in all specimens. The major polyunsaturated fatty acids (PUFA) in the major lipid classes of T. cornutus were 20:4n-6 (arachidonic acid; ARA), 20:5n-3 (ecosapentaenoic acid; EPA), 22:4n-6, and 22:5n-3 (docosapentaenoic acid; n-3 DPA), with very low levels of 22:6n-3 (docosahexaenoic acid; DHA). The unusual high levels of ARA, 22:4n-6, and n-3 DPA found in both the triacylglycerols and phospholipids of all specimens suggest the influence of dietary algae on its tissue lipids. In the polar lipids, the total PUFA content was consistently high, with n-6 PUFA compensating for the fluctuation in the total n-3 PUFA levels. T. cornutus concentrated high levels of ARA in the visceral lipids from the dietary algae whose lipid content were very low. The viscera may effectively serve as a source of ARA for infant formulas. High levels of ARA, EPA, and n-3 DPA in the phospholipids of T. cornutus were observed. T. cornutus is a healthful marine food containing high levels of n-3 DPA.

Characterization of crustin antimicrobial proteins from Japanese spiny lobster Panulirus japonicus.

Crustin antimicrobial proteins (PJC1-4) were identified from a phyllosoma library of Japanese spiny lobster, Panulirus japonicus. The deduced amino acid sequences of PJC1-4 contained open reading frames of 130, 139, 124 and 150 amino acid residues, respectively. These proteins contained a glycine-rich region at the N-terminus and 12 conserved cysteine residues containing a single whey acidic protein (WAP) domain at the C-terminus. A phylogenetic tree and sequences alignment analyses revealed that PJC1-4 are more closely related to shrimp crustins than to other lobster crustins. Transcripts of PJC1, 3 and 4 were detected in heart, nerves, intestine, hemocytes, gills and hepatopancreas, while transcripts of PJC2 were detected only in nerves.

Characterization of two isoforms of Japanese spiny lobster Panulirus japonicus defensin cDNA.

Antimicrobial peptides (AMPs) are components of the innate immune responses that form the first line of host defense against pathogens. In this study, cDNAs of two new isoforms of defensin (designated PJD1 and PJD2) from a Japanese spiny lobster Panulirus japonicus haemocytes cDNA library were cloned and sequenced. PJD1 and PJD2 consist of 656 and 673 nucleotides encoding putative proteins of 66 and 64 amino acids, respectively. The isoforms share 74.2% amino acid identity. In a phylogenetic analysis, the peptides clustered with vertebrate defensins and were closely mostly related to chicken beta-defensin. PJD1 and PJD2 were detected in all tissues examined including heart, nerves, intestine, haemocytes, gills and hepatopancreas.

Competent stripes for diverse positions of limbs/fins in gnathostome embryos.

Every vertebrate species has its own unique morphology adapted to a particular lifestyle and habitat. Limbs and fins are strikingly diversified in size, shape, and position along the body axis. This diversity in morphology suggests the existence of a variety of embryonic developmental programs. However, comparisons of various embryos suggest common mechanisms underlying limb/fin formation. Here, we report the existence of continuous stripes of competency for appendage formation along the dorsal midline and the lateral trunk of all of the major jawed vertebrate (gnathostome) groups. We also show that the developing fin buds of cartilaginous fish share a mechanism of anterior-posterior axis formation as well as an shh (sonic hedgehog) expression domain in the posterior bud. We hypothesize a continuous distribution of competent stripes that represents the common developmental program at the root of appendage formation in gnathostomes. This schema would have permitted subsequent divergence into various levels of limbs/fins in each animal group.

Noncanonical role of Hox14 revealed by its expression patterns in lamprey and shark.

Hox genes are arranged in uninterrupted clusters in vertebrate genomes, and the nested patterns of their expression define spatial identities in multiple embryonic tissues. The ancestral Hox cluster of vertebrates has long been thought to consist of, maximally, 13 Hox genes. However, recently, Hox14 genes were discovered in three chordate lineages, the coelacanth, cartilaginous fishes, and amphioxus, but their expression patterns have not yet been analyzed. We isolated Hox14 cDNAs from the Japanese lamprey and cloudy catshark. These genes were not expressed in the central nervous systems, somites, or fin buds/folds but were expressed in a restricted cell population surrounding the hindgut. The lack of Hox14 expression in most of the embryonic axial elements, where nested Hox expressions define spatial identities, suggests a decoupling of Hox14 genes' regulation from the ancestral regulatory mechanism. The relaxation of preexisting constraint for collinear expression may have permitted the secondary losses of this Hox member in the tetrapod and teleost lineages.

Vibrio comitans sp. nov., Vibrio rarus sp. nov. and Vibrio inusitatus sp. nov., from the gut of the abalones Haliotis discus discus, H. gigantea, H. madaka and H. rufescens.

Nine alginolytic, facultatively anaerobic, non-motile bacteria were isolated from the guts of the abalones Haliotis discus discus, H. gigantea, H. madaka and H. rufescens. Phylogenetic analyses based on 16S rRNA gene sequences indicated that these bacteria were closely related to Vibrio superstes G3-29(T) (98.6-99.3 % sequence similarity). DNA-DNA hybridization and phylogenetic analysis based on the gapA gene demonstrated that six strains constituted one bacterial species, two strains represented a second species and one strain represented a third species. The three novel bacterial species were different from all currently known vibrios. The names Vibrio comitans sp. nov. (type strain GHG2-1(T)=LMG 23416(T)=NBRC 102076(T); DNA G+C content 45.0-48.0 mol%), Vibrio inusitatus sp. nov. (type strain RW14(T)=LMG 23434(T)=NBRC 102082(T); DNA G+C content 43.1-43.7 mol%) and Vibrio rarus sp. nov. (type strain RW22(T)=LMG 23674(T)=NBRC 102084(T); DNA G+C content 43.8 mol%) are proposed to encompass these new taxa. Several phenotypic features were revealed that discriminate V. comitans, V. rarus and V. inusitatus from other Vibrio species.