Development of a chub mackerel with less-aggressive fry stage by genome editing of arginine vasotocin receptor V1a2.

Genome editing is a technology that can remarkably accelerate crop and animal breeding via artificial induction of desired traits with high accuracy. This study aimed to develop a chub mackerel variety with reduced aggression using an experimental system that enables efficient egg collection and genome editing. Sexual maturation and control of spawning season and time were technologically facilitated by controlling the photoperiod and water temperature of the rearing tank.

Comprehensive Experimental System for a Promising Model Organism Candidate for Marine Teleosts.

A comprehensive experimental system for Japanese anchovy, a promising candidate model organism for marine teleosts, was established. Through the design of a rearing/spawning facility that controls the photoperiod and water temperature, one-cell eggs were continuously obtained shortly after spawning throughout the rearing period. The stages of eggs are indispensable for microinjection experiments, and we developed an efficient and robust microinjection system for the Japanese anchovy.

Two vitellogenins in the loliginid squid Uroteuthis edulis: Identification and specific expression in ovarian follicles.

Vitellogenenesis is a physiological process common in oviparous animals. The molecular profile, modifications, and utilization of vitellogenin (VTG), a precursor of yolk protein, have been characterized in various taxa to understand oogenesis within different modes of reproduction. Hormonal regulation of VTGs has been investigated in invertebrates, such as insects and crustaceans; conversely, little is known for cephalopods.

Kiss1 hexadecapeptide directly regulates gonadotropin-releasing hormone 1 in the scombroid fish, chub mackerel.

Here we report that the Kiss1 hexadecapeptide (Kiss1-16) directly regulates the functional form of gonadotropin-releasing hormone (GnRH) in the preoptic area (POA) of a scombroid fish model. In this study, we analyzed the localization of two kisspeptin (kiss1 and kiss2) neurons and two kisspeptin receptors (kissr1 and kissr2) in the brain of adult chub mackerel using in situ hybridization to determine whether the kisspeptin receptors co-localize with GnRH1 neurons. The kiss1- and kiss2-expressing neurons were mainly localized in the nucleus recessus lateralis (NRL) and the nucleus of the posterior recess (NRP) in the hypothalamus.

Possible role of the leptin system in controlling puberty in the male chub mackerel, Scomber japonicus.

Leptin directly regulates kisspeptin neurons in the hypothalamus and gonadotropin secretion from the pituitary, making it a central player in the onset of mammalian puberty. Recently, we identified two leptin genes (lepa and lepb) and a single leptin receptor (lepr) in the marine perciform fish chub mackerel; however, the expression of these genes did not correlate with the expression of important reproductive genes or ovarian stage during female puberty. Here, we expand upon these initial observations by evaluating the expression of lepa, lepb, and lepr during pubertal transition and under differential feeding conditions in the male chub mackerel.

Two leptin genes and a leptin receptor gene of female chub mackerel (Scomber japonicus): Molecular cloning, tissue distribution and expression in different obesity indices and pubertal stages.

Leptin is a hormone produced by fat cells that regulates the amount of fat stored in the body and conveys nutritional status to the reproductive axis in mammals. In the present study we identified two subtypes of leptin genes (lepa and lepb) and a leptin receptor gene (lepr) from chub mackerel (Scomber japonicus) and there gene expression under different feeding conditions (control and high-feed) and pubertal development stages was analyzed using quantitative real-time PCR. The protein lengths of LepA, LepB and LepR were 161 amino acids (aa), 163 aa and 1149 aa, respectively and both leptin subtypes shared only 15% similarity in aa sequences.

Expression changes of mRNAs encoding kisspeptins and their receptors and gonadotropin-releasing hormones during early development and gonadal sex differentiation periods in the brain of chub mackerel (Scomber japonicus).

In recent years, brain kisspeptin system has been shown to be involved in diverse reproductive function, including sexual differentiation in vertebrates. Our previous reports demonstrated that the chub mackerel (Scomber japonicus) brain expresses two kisspeptin (kiss1, kiss2), two kisspeptin receptor (kissr1, kissr2) and three gonadotropin-releasing hormone (gnrh1, gnrh2, gnrh3) genes. In the present study, using quantitative real-time PCR (qRT-PCR) assays, we analysed expression changes of these genes during early development (0-30dphs) and gonadal sex differentiation periods (37-60dphs).

Identification and distribution of three gonadotropin-releasing hormone (GnRH) isoforms in the brain of a clupeiform fish, Engraulis japonicus.

To gain a better understanding of the reproductive endocrinology of a primitive order clupeiform fish (Japanese anchovy, Engraulis japonicus), cDNAs encoding three gonadotropin-releasing hormone (GnRH) isoforms were isolated from the brain, and their distribution was analyzed using insitu hybridization (ISH). The three GnRH isoforms include GnRH1 (herring GnRH), GnRH2 (chicken GnRH-ll) and GnRH3 (salmon GnRH), and their full-length cDNAs encode 88, 86, and 89 deduced amino acids (aa), respectively. Alignment analysis of Japanese anchovy GnRH isoforms showed lower identities with other teleost fish.

Identification, characterization, and expression profiles of two subtypes of kisspeptin receptors in a scombroid fish (chub mackerel).

The kisspeptin receptor (Kiss1R) is a cognate receptor for kisspeptin (Kiss), and this Kiss-Kiss1R system has been shown to regulate seasonal reproduction in vertebrates. Our previous study found the chub mackerel (Scomber japonicus) brain expresses both kiss1 and kiss2 and exhibits sexually dimorphic changes during the seasonal reproductive cycle. The present study cloned two subtypes of kissr from the chub mackerel brain, and their signal transduction pathways to Kiss1 and Kiss2 were characterized in a mammalian cell line.

Subcutaneous administration of Kiss1 pentadecapeptide accelerates spermatogenesis in prepubertal male chub mackerel (Scomber japonicus).

Kisspeptins, encoded by kiss genes, have emerged as critical regulator of reproductive function in vertebrates. Our previous studies demonstrated that the chub mackerel (Scomber japonicus) brain expresses kiss1 and kiss2 and peripheral administration of synthetic Kiss1 pentadecapeptide (Kiss1-15) but not Kiss2 dodecapeptide (Kiss2-12) induces spermiation in sexually immature adult chub mackerel. In the present study, we evaluated the potency of Kiss1-15, Kiss2-12, and GnRH analogue (GnRHa) to induce pubertal onset in prepubertal chub mackerel.

In vitro characterization of the RS motif in N-terminal head domain of goldfish germinal vesicle lamin B3 necessary for phosphorylation of the p34cdc2 target serine by SRPK1.

The nuclear envelopes surrounding the oocyte germinal vesicles of lower vertebrates (fish and frog) are supported by the lamina, which consists of the protein lamin B3 encoded by a gene found also in birds but lost in the lineage leading to mammals. Like other members of the lamin family, goldfish lamin B3 (gfLB3) contains two putative consensus phosphoacceptor p34cdc2 sites (Ser-28 and Ser-398) for the M-phase kinase to regulate lamin polymerization on the N- and C-terminal regions flanking a central rod domain. Partial phosphorylation of gfLB3 occurs on Ser-28 in the N-terminal head domain in immature oocytes prior to germinal vesicle breakdown, which suggests continual rearrangement of lamins by a novel lamin kinase in fish oocytes.

Peripheral administration of Kiss1 pentadecapeptide induces gonadal development in sexually immature adult scombroid fish.

Kisspeptins have emerged as potent regulators of the reproductive brain-pituitary-gonad (BPG) axis. Our previous study demonstrated that the brain of the chub mackerel (Scomber japonicus), a scombroid fish, expresses two kisspeptin-encoding genes, kiss1 and kiss2, and exhibits sexually dimorphic expression profiles. Recent studies strongly suggest that teleost Kiss1 and Kiss2 precursors produce mature Kiss1-pentadecapeptides (Kiss1-15) and Kiss2-dodecapeptides (Kiss2-12), respectively.

Characterization, localization, and stage-dependent gene expression of gonadotropin receptors in chub mackerel (Scomber japonicus) ovarian follicles.

The pituitary gonadotropins (GtHs), follicle-stimulating hormone (FSH) and luteinizing hormone (LH), are key regulators of gametogenesis in teleosts. However, little is known about the physiological mechanisms by which GtHs regulate asynchronous oocyte development in multiple-spawning marine fishes. We cloned cDNAs encoding GtH receptors (FSHR and LHR) from chub mackerel (Scomber japonicus).

Steroidogenic and maturation-inducing potency of native gonadotropic hormones in female chub mackerel, Scomber japonicus.

Background: The gonadotropins (GtHs), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are produced in the pituitary gland and regulates gametogenesis through production of gonadal steroids. However, respective roles of two GtHs in the teleosts are still incompletely characterized due to technical difficulties in the purification of native GtHs.

Methods: Native FSH and LH were purified from the pituitaries of adult chub mackerel, Scomber japonicus by anion-exchange chromatography and immunoblotting using specific antisera.

Immunoreactivity of gonadotrophs (FSH and LH Cells) and gonadotropin subunit gene expression in the male chub mackerel Scomber japonicus pituitary during the reproductive cycle.

The gonadotropins (GtHs), follicle-stimulating hormone (FSH) and luteinizing hormone (LH), are heterodimers composed of a common α subunit (GPα) and a unique β subunit (FSHβ or LHβ); they are synthesized in and secreted from gonadotrophs (FSH and LH cells) in the pituitary. Little is known about the roles of FSH and LH during spermatogenesis in perciform fishes. In this study, we examined immunoreactive changes in FSH and LH cells, and changes in the gene expression of the three gonadotropin subunits in the pituitary of male chub mackerel Scomber japonicus during testicular development.

Increased expression of kisspeptin and GnRH forms in the brain of scombroid fish during final ovarian maturation and ovulation.

Background: Kisspeptins (Kiss) are prime players in the control of reproductive function through their regulation of gonadotropin-releasing hormone (GnRH) expression in the brain. The experimental scombroid fish, chub mackerel (Scomber japonicus) expresses two kiss (kiss1 and kiss2) and three gnrh (gnrh1, gnrh2, and gnrh3) forms in the brain. In the present study, we analyzed expression changes of kiss and gnrh mRNAs in the brain and corresponding GnRH peptides in the brain and pituitary during final ovarian maturation (FOM) and ovulation.

Changes in the expression of pituitary gonadotropin subunits during reproductive cycle of multiple spawning female chub mackerel Scomber japonicus.

The endocrine regulation of reproduction in a multiple spawning fish with an asynchronous-type ovary remains largely unknown. The objectives of this study were to monitor changes in the mRNA expression of three gonadotropin (GtH) subunits (GPα, FSHβ, and LHβ) during the reproductive cycle of the female chub mackerel Scomber japonicus. Cloning and subsequent sequence analysis revealed that the cDNAs of chub mackerel GPα, FSHβ, and LHβ were 658, 535, and 599 nucleotides in length and encoded 117, 115, and 147 amino acids, respectively.

Molecular cloning of two gonadotropin receptors and their distinct mRNA expression profiles in daily oogenesis of the wrasse Pseudolabrus sieboldi.

In fish, asynchronous development of ovarian follicles, the simultaneous advance of vitellogenesis and oocyte maturation in one ovary, is a rational reproductive strategy to spawn consecutively in one spawning season. In this study, to clarify the mode of action of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in asynchronous ovarian follicle development in daily egg production, we cloned cDNAs of the follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHR) in the bambooleaf wrasse (Pseudolabrus sieboldi), which exhibits clear diurnal spawning rhythms over 1 month. In addition, different developmental stages of ovarian follicles were isolated from whole ovaries at various daily time points on 1 day in the spawning season, and mRNA expression levels of FSHR and LHR were analyzed.

Diurnal dynamics of S-phase entry of germ cells in the secondary testis of the bambooleaf wrasse (Pseudolabrus sieboldi).

The diversity of reproductive strategies found in fish is attributed to the adaptation of gametogenesis to different habitats. To date, however, information about the dynamics of male gametogenesis and its molecular mechanisms of control by the brain-pituitary-gonadal (BPG) axis, a well-known facet of the endocrine system in vertebrates, is not sufficient to explain the variation in spawning and regulatory mechanisms among species. The bambooleaf wrasse (Pseudolabrus sieboldi) is a protogynous hermaphrodite fish that shows clear diurnal fluctuations in gonadotropin gene expression and serum sex steroid levels associated with spawning.

Molecular characterization, tissue distribution, and mRNA expression profiles of two Kiss genes in the adult male and female chub mackerel (Scomber japonicus) during different gonadal stages.

Kisspeptins, encoded by the Kiss1 gene, have emerged as key modulators of reproduction in mammals. In contrast to the placental mammals, some teleosts express two Kiss genes, Kiss1 and Kiss2. In the present study, full-length cDNAs of Kiss1 and Kiss2 in the chub mackerel were cloned and sequenced.

Immunological characterization and distribution of three GnRH forms in the brain and pituitary gland of chub mackerel (Scomber japonicus).

The presence of three gonadotropin-releasing hormone (GnRH) forms in the brain of the chub mackerel, Scomber japonicus, namely, salmon GnRH (sGnRH), chicken GnRH-II (cGnRH-II), and seabream GnRH (sbGnRH), was confirmed by combined high performance liquid chromatography (HPLC) and time-resolved fluoroimmunoassay (TR-FIA). Immunocytochemical localization of the three GnRH forms in the brain was Investigated by using specific antisera, to elucidate possible roles of each GnRH form in reproduction in this species, and double immunolabeling was used to localize GnRH-ir (immunoreactive) fibers Innervating the pituitary. sGnRH-ir neurons were localized in the ventral olfactory bulb and terminal nerve ganglion region.