The mechanism for primordial germ-cell migration is conserved between Japanese eel and zebrafish.

Primordial germ cells (PGCs) are segregated and specified from somatic cells during early development. These cells arise elsewhere and have to migrate across the embryo to reach developing gonadal precursors. Several molecules associated with PGC migration (i.

Generation of germ-line chimera zebrafish using primordial germ cells isolated from cultured blastomeres and cryopreserved embryoids.

Primordial germ cells (PGCs) are the only cells in developing embryos with the potential to transmit genetic information to the next generation. In our previous study, a single PGC transplanted into a host differentiated into fertile gametes and produced germ-line chimeras of cyprinid fish, including zebrafish. In this study, we aimed to induce germ-line chimeras by transplanting donor PGCs from various sources (normal embryos at different stages, dissociated blastomeres, embryoids, or embryoids cryopreserved by vitrification) into host blastulae, and compare the migration rates of the PGCs towards the gonadal ridge.

Isolation of teleost primordial germ cells using flow cytometry.

Primordial germ cells (PGCs) generate gametes, the only cells that can transmit genetic information to the next generation. A previous report demonstrated that a fusion construct of green fluorescent protein (gfp) and zebrafish nos 1 3UTR mRNA could be used to label PGCs in a number of fish species. Here, we sought to exploit this labeling strategy to isolate teleost PGCs by flow cytometry (FCM), and to use these isolated PGCs to examine germ cell migration to the gonadal region.

Inter-species transplantation and migration of primordial germ cells in cyprinid fish.

Primordial germ cells (PGCs) are the only cells in developing embryos that can transmit genetic information to the next generation. PGCs therefore have considerable potential value for gene banking and cryopreservation, particularly via production of donor gametes using germ-line chimeras. In some animal species, including teleost fish, the feasibility of using PGC transplantation to obtain donor-derived offspring, within and between species, has been demonstrated.

Sexual dimorphism of gonadal structure and gene expression in germ cell-deficient loach, a teleost fish.

Germ cell-deficient fish usually develop as phenotypic males. Thus, the presence of germ cells is generally considered to be essential for female gonadal differentiation or the maintenance of ovarian structure. However, little is known of the role of germ cells in the determination of the sexual fate of gonadal somatic cells.

Molecular cloning, characterization and expression of thyroid-stimulating hormone receptor in channel catfish.

Thyroid-stimulating hormone receptors (TSHRs) are primarily expressed in the thyroid of vertebrates, however recently, transcripts encoding TSHR have been found abundantly in the gonads in a variety of fish species. The purpose of this study is to characterize the channel catfish TSHR and to examine whether the transcript are translated into protein in the gonad or store the transcript as maternal RNA for later use. The cDNA encoding the TSHR was isolated from the channel catfish thyroid but the transcript was determined to be expressed in a number of tissues, including the gonads.

Xenogenesis in teleost fish through generation of germ-line chimeras by single primordial germ cell transplantation.

Primordial germ cells (PGCs) are the only cells in developing embryos with the potential to transmit genetic information to the next generation. PGCs therefore have the potential to be of value for gene banking and cryopreservation, particularly via the production of donor gametes with germ-line chimeras. Currently, it is not clear how many PGCs are required for germ-line differentiation and formation of gonadal structures.

Short-term exposure to low concentrations of the synthetic androgen methyltestosterone affects vitellogenin and steroid levels in adult male zebrafish (Danio rerio).

Short-term effects of methyltestosterone (MT) on the endocrine system of adult male zebrafish (Danio rerio) were examined. Males were exposed to 0, 4.5, 6.

Molecular characterization of three forms of putative membrane-bound progestin receptors and their tissue-distribution in channel catfish, Ictalurus punctatus.

Membrane-bound progestin receptors (mPR) were recently cloned and characterized as a new class of steroid receptors that transduce cell-signals through alteration of MAP kinase- and cAMP-dependent pathways. To further develop our understanding of this new class of steroid receptors, we characterized the cDNAs and genes of thealpha, beta and gamma forms of the channel catfish mPRs (IpmPR). The predicted alpha and beta proteins have 49% sequence identity, whereas they only have 30% and 27% identities, respectively, with the gamma form.

Membrane-bound progestin receptors in channel catfish and zebrafish ovary: changes in gene expression associated with the reproductive cycles and hormonal reagents.

Membrane-bound progestin receptors (mPRs) are potential intermediaries in meiotic maturation of fish oocytes and other physiological processes. In this study, gene expression of the mPRs in the ovary of catfish and zebrafish during the reproductive cycle and the hormonal regulation of the expression were investigated. The transcript abundance of catfish mPRalpha gradually increased in conjunction with ovarian growth and then decreased prior to spawning period whereas the ovarian gene expression of mPRbeta varied little throughout the reproductive cycle.

Localization and expression of aromatase mRNA in adult zebrafish.

Estradiol plays a key role in the control of many behavioral and physiological aspects of reproduction therefore the expression of cytochrome P450 aromatase (CYP19), the enzyme responsible for the conversion of androgens to estrogens, is of vital interest. The zebrafish, and many other teleosts, have two aromatase genes (CYP19A1 and CYP19A2) that are expressed predominantly in the ovary and brain, respectively, however, the physiological impact of extra-gonadal aromatase has been poorly described. In this study, in situ hybridizations of whole-mount and paraffin sections of adult zebrafish brains, pituitaries, and ovarian follicles showed that CYP19A2 was strongly expressed in the olfactory bulb (OB), ventral telencephalon (TEL), preoptic area (POA), and ventral/caudal hypothalamic zone (HT) of the brain, and in the anterior and posterior lobes of the pituitary.