Immunohistochemical Localization of a GnRH-Like Peptide in the Nerve Ganglion of Three Classes of Crustaceans, the Tadpole Shrimp (Branchiopoda), the Barnacle (Hexanauplia), and the Hermit Crab (Malacostraca).

In vertebrates, gonadotropin-releasing hormone (GnRH) regulates gonadal maturation by stimulating the synthesis and release of pituitary gonadotropins. GnRH has also been identified in invertebrates. Crustacea consists of several classes including Cephalocarida, Remipedia, Branchiopoda (e.

Lipids, fatty acids and hydroxy-fatty acids of Euphausia pacifica.

Euphausia pacifica is a good candidate for a resource of marine n-3 PUFA. However, few reports exist of the lipid and fatty acid composition of E. pacifica.

Biochemical analysis and immunohistochemical examination of a GnRH-like immunoreactive peptide in the central nervous system of a decapod crustacean, the kuruma prawn (Marsupenaeus japonicus).

We examined whether a gonadotropin-releasing hormone (GnRH)-like peptide exists in the central nervous system (CNS) of the kuruma prawn, Marsupenaeus japonicus, by reverse-phase high performance liquid chromatography (rpHPLC) combined with time-resolved fluoroimmunoassay (TR-FIA) analysis and by immunohistochemistry. The displacement curve obtained for serially diluted extracts of the kuruma prawn brain paralleled the chicken GnRH-II (cGnRH-II) standard curve obtained by cGnRH-II TR-FIA using the anti-cGnRH-II antibody, which cross-reacts not only with cGnRH-II but also with lamprey GnRH-II (lGnRH-II) and octopus GnRH (octGnRH). Extracts of kuruma prawn brains and eyestalks showed a similar retention time to synthetic lGnRH-II and octGnRH in rpHPLC combined with TR-FIA analysis.

Feeding restriction alters expression of some ATP related genes more sensitively than the RNA/DNA ratio in zebrafish, Danio rerio.

The growth rate of fish shows extensive plasticity in response to various environments. Metabolic responses of fish to excessive nutritional shortages such as starvation have been reported, but the effects of moderate nutrient shortage remain unclear. We examined expression levels of some genes related to ATP metabolism and to myogenesis, the RNA/DNA ratio, and the protein/DNA ratio of fish under different feeding conditions: a diet of 212-432% (frequent feeding, FR) or 32-82% (restricted feeding, RE) of initial body weight per week was supplied.

Effects of bilateral and unilateral eyestalk ablation on vitellogenin synthesis in immature female kuruma prawns, Marsupenaeus japonicus.

In penaeid shrimp species, vitellogenin (VTG) synthesis in the ovary and hepatopancreas is under the inhibitory regulation of a neuroendocrine system, the X-organ/sinus gland complex in the paired eyestalks, and eyestalk ablation (removal of the X-organ/sinus gland complex) is widely used for inducing ovarian development. However, the difference in effects of bilateral and unilateral ablation on VTG gene expression has not been clarified so far. In the present study, VTG synthesis was monitored over a 16-day period after ablation and compared between replicates of immature female kuruma prawns, Marsupenaeus (Penaeus) japonicus, that had been bilaterally or unilaterally ablated and control specimens.

Vitellogenin gene expression and hemolymph vitellogenin during vitellogenesis, final maturation, and oviposition in female kuruma prawn, Marsupenaeus japonicus.

In penaeid shrimps, vitellogenin (VTG), the precursor of vitellin, is synthesized in the ovary and hepatopancreas and accumulated in oocytes during ovarian development. In the present study, VTG gene expression levels and hemolymph VTG levels were determined throughout ovarian development in female kuruma prawn, Marsupenaeus japonicus. Hemolymph VTG levels and VTG mRNA levels in the ovary and hepatopancreas were high during vitellogenesis, remained high until final maturation, and then decreased after oviposition.

Molecular characterization of lipoprotein lipase, hepatic lipase and pancreatic lipase genes: effects of fasting and refeeding on their gene expression in red sea bream Pagrus major.

To investigate the nutritional regulation of lipid metabolism in fish, molecular characterization of lipases was conducted in red sea bream Pagrus major, and the effects of fasting and refeeding on their gene expression was examined. Together with data from a previous study, a total of four lipase genes were identified and characterized as lipoprotein lipase (LPL), hepatic lipase (HL) and pancreatic lipase (PL). These four lipase genes, termed LPL1, LPL2, HL and PL, share a high degree of similarity.

Effects of insulin, triiodothyronine and fat soluble vitamins on adipocyte differentiation and LPL gene expression in the stromal-vascular cells of red sea bream, Pagrus major.

Various kinds of hormones including insulin, triiodothyronine (T(3)) and fat-soluble vitamins have been proposed as mediators of adipocyte differentiation in mammals. To investigate the factors which are responsible for fish adipocyte differentiation, we developed a serum-free culture system of stromal-vascular cells of red sea bream adipose tissue and examined the effects of bovine insulin, T(3), and fat-soluble vitamins (all-trans retinoic acid, retinyl acetate and 1,25-dihydroxyvitamin D(3)) on the differentiation-linked expression of the lipoprotein lipase (LPL) gene. As assessed by the increase in LPL gene expression after 3 day cultivation, like in mammalian adipocytes, insulin enhanced the adipocyte differentiation in a concentration-dependent manner.

Effects of lipopolysaccharide on gene expression of antimicrobial peptides (penaeidins and crustin), serine proteinase and prophenoloxidase in haemocytes of the Pacific white shrimp, Litopenaeus vannamei.

For shrimp immune defences, prophenoloxidase (proPO) activating system and antimicrobial peptides in circulating haemocytes play important roles. In the present study, the effects of lipopolysaccharide (LPS) injection on gene expression of penaeidins, crustin, serine proteinase and proPO in haemocytes were determined using real-time reverse transcription-polymerase chain reaction (PCR) in the Pacific white shrimp Litopenaeus vannamei. After injection of LPS, mRNA levels of antimicrobial peptides, penaeidin 2 (PEN2), penaeidin 3 (PEN3), penaeidin 4 (PEN4) and crustin decreased in a dose-dependent manner, while mRNA levels of serine proteinase and proPO did not change significantly.

Effects of cyclic nucleotides, calcium ionophore, and phorbol ester on vitellogenin mRNA levels in incubated ovarian fragments of the kuruma prawn Marsupenaeus japonicus.

In crustaceans, vitellogenin (VTG, the precursor of major yolk protein) is synthesized in the ovary and/or hepatopancreas, and its synthesis is considered to be under the negative control of the vitellogenesis-inhibiting hormone (VIH), a neuropeptide secreted from the X-organ/sinus gland complex in the eyestalks. In the present study, the effects of pharmacological agents on VTG mRNA levels in incubated ovarian fragments of the kuruma prawn Marsupenaeus japonicus were examined to determine the intracellular signalling pathways for VTG synthesis. After 24 h incubation, A23187 (calcium ionophore), dibutyl-cAMP (cAMP analogue), dibutyl-cGMP (cGMP analogue), forskolin (adenylate cyclase activator), 3-isobutyl-1-methylxanthine (IBMX, phosphodiesterase inhibitor), and phorbol 12-myristate 13-acetate (PMA, protein kinase C activator) decreased VTG mRNA levels in the ovarian fragments.

Expression of vitellogenin and cortical rod proteins during induced ovarian development by eyestalk ablation in the kuruma prawn, Marsupenaeus japonicus.

In penaeid shrimp species, ovarian development is characterized by the accumulation of a major yolk protein (vitellin) and the formation of cortical rods in the oocytes. The process is considered to be under the control of a neuroendocrine organ in the eyestalk (the X-organ sinus gland complex). In the present study, the synthesis of vitellogenin (VTG, precursor of vitellin) and two kinds of cortical rod proteins (cortical rod protein, CRP; thrombospondin, MjTSP) was induced by bilateral eyestalk ablation (removal of the X-organ sinus gland complex) in immature female kuruma prawn, Marsupenaeus japonicus, and the synthesis process was monitored over a 7-day period after the ablation.

Production and characterization of recombinant vitellogenesis-inhibiting hormone from the American lobster Homarus americanus.

Recombinant peptides related to vitellogenesis-inhibiting hormone (VIH) of the American lobster Homarus americanus were expressed in bacterial cells, and then purified after being allowed to refold. Biological activities of the recombinant VIHs having an amidated C-terminus (rHoa-VIH-amide) and a free carboxyl-terminus (rHoa-VIH-OH) were examined using an ovarian fragment incubation system derived from the kuruma prawn, Marsupenaeus japonicus. The rHoa-VIH-amide significantly reduced vitellogenin mRNA levels in the ovary, while rHoa-VIH-OH had no effect.

Localization and developmental expression of mRNA for cortical rod protein in kuruma prawn Marsupenaeus japonicus.

The mature penaeid oocytes possess cortical rods that contain two related cortical rod proteins (CRP, 28.6 kDa and 30.5 kDa).

In vivo effects of a recombinant molt-inhibiting hormone on molt interval and hemolymph ecdysteroid level in the kuruma prawn, Marsupenaeus japonicus.

In order to determine the function of molt-inhibiting hormone (MIH) in vivo, we examined the effects of injecting of a recombinant MIH on the molt interval and hemolymph ecdysteroid level in the kuruma prawn, Marsupenaeus japonicus. The injection of recombinant MIH significantly prolonged the molt interval (9.0 +/-0.

Ovarian development and hemolymph vitellogenin levels in laboratory-maintained protandric shrimp, Pandalus hypsinotus: measurement by a newly developed time-resolved fluoroimmunoassay (TR-FIA).

Most pandalid shrimps exhibit protandric hermaphroditism, and detailed information on ovarian development of pandalid species is important for a better understanding of vitellogenesis in crustacean species. In the present study, we characterized ovarian development under light and electron microscopy and examined the hemolymph vitellogenin levels in the coonstriped shrimp, Pandalus hypsinotus under laboratory conditions. To measure vitellogenin levels, a time-resolved fluoroimmunoassay (TR-FIA) was developed after purification of vitellin and production of the anti-vitellin antiserum.

Molecular characterization of a cDNA encoding vitellogenin in the coonstriped shrimp, Pandalus hypsinotus and site of vitellogenin mRNA expression.

In order to determine the primary structure of vitellogenin in a protandric species, the coonstriped shrimp Pandalus hypsinotus, we previously purified four vitellin components (designated as VnA, VnB, VnC, and VnD, respectively), and chemically analyzed their partial amino acid sequences. In this study, we subsequently cloned a cDNA encoding vitellogenin in this species based on the N-terminal and internal amino acid sequences of VnA, as well as the N-terminal sequence of VnC. The open reading frame of this cDNA encoded a pro-vitellogenin in which vitellins were arranged as follows: NH2-VnA-VnB-VnC/D-COOH.

Androgenic gland cell structure and spermatogenesis during the molt cycle and correlation to morphotypic differentiation in the giant freshwater prawn, Macrobrachium rosenbergii.

The freshwater prawn Macrobrachium rosenbergii shows three male morphotypes: blue-claw males (final stage having high mating activity), orange-claw males (transitional stage showing rapid somatic growth), and small males (primary stage showing sneak copulation). This morphotypic differentiation is considered to be controlled by androgenic gland hormone, which is probably a peptide hormone. However, its physiological roles are not fully understood.