Black rockfish (Sebastes schlegelii) and its relatives are viviparous marine fish. Males produce urinary proteins during the copulation season; however, the identity of these proteins was unknown. In this study, we focused on high-molecular-weight urinary proteins (HMWups) in male black rockfish.
View Article and Find Full Text PDFViviparous fish, including white-edged rockfish (), accumulate substantial yolk mass in the oocytes; however, the details of the molecular mechanisms underlying yolk formation are not yet fully understood, especially concerning multiplicity in the yolk precursor vitellogenin (Vtg). The present study aimed to reveal the hepatic transcriptional profiles of multiple gene transcripts (, , ) during the reproductive cycle in captive female white-edged rockfish reared in an aquarium under natural photo-thermal conditions. The serum estradiol-17β concentration and the hepatic transcript levels of all subtypes increased with the progress of vitellogenesis; both levels decreased at the beginning of oocyte maturation and remained low during the gestation period.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
November 2021
Fundamental knowledge on the regulation of reproduction by gonadotropins (Gths) is quite limited in viviparous fishes. In the present study, we performed molecular cloning and characterization of cDNAs encoding two Gth subunits (fshb and lhb) from the pituitaries of viviparous white-edged rockfish, Sebastes taczanowskii; expression profiles of both gene transcripts were elucidated in the pituitaries of reproductive males and females which were kept in a captive environment. The cloned fshb and lhb fragments exhibited high sequence identities with corresponding β-subunit sequences from black rockfish, S.
View Article and Find Full Text PDFEstradiol-17β (E2) regulates transcription of estrogen-responsive genes via estrogen receptors (Esr). In many teleost species, choriogenin (chg), vitellogenin (vtg) and esr genes are transactivated by E2 in the liver. This study aimed i) to compare expression properties of all subtypes of these genes (chg: chgHα, chgHβ, chgL; vtg: vtgAs, vtgC; esr: esr1a, esr1b, esr2a, esr2b) in response to estrogen stimulation, and ii) to confirm how each of four Esr subtypes is involved in the transcriptional regulation of these estrogen-responsive genes in cutthroat trout hepatocytes.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
July 2021
Recent studies of vitellogenesis engendered a novel model of teleost yolk formation in which multiple yolk precursors, vitellogenins (Vtgs), and their receptors (Vtgrs) interact to ensure proper yolk composition for embryonic development and larval growth. As a step toward verification of this concept, we examined the role of one candidate Vtgr, termed low-density lipoprotein receptor relative with eight ligand-binding repeat (Lr8), in the medaka, a representative teleost and established laboratory model. A homozygous lr8 knock out (lr8-KO) medaka was produced to perform reverse-genetic functional analyses.
View Article and Find Full Text PDFNon-competitive, enzyme-linked immunosorbent assays (ELISAs) for three distinct sole vitellogenins (VtgAa, VtgAb and VtgC) were designed using their purified lipovitellin (Lv) products and corresponding digoxigenin-labeled, anti-Lv polyclonal antibodies, primarily for employment in monitoring estrogenic pollution of the environment. The working range of the ELISAs was from 0.97 to 1,000 ng/mL for all Vtg subtypes.
View Article and Find Full Text PDFEstradiol-17β (E2) and 11-ketotestosterone (11KT) have been implicated in vitellogenesis and in regulating expression of the follicle-stimulating hormone receptor (fshr), respectively. To override the captivity-induced reproductive block in shortfinned eel, Anguilla australis, we hypothesized that in combination, 11KT and E2 would stimulate ovarian uptake of vitellogenin (Vtg). Early pubertal eels received hormone implants containing varying concentrations of E2 (0, 0.
View Article and Find Full Text PDFChemiluminescent immunoassays (CLIAs) were developed for each of three subtypes of vitellogenin (VtgAa, VtgAb and VtgC) in grey mullet, primarily for use in monitoring estrogenic pollution of the environment. The working range of VtgAa-CLIA and VtgAb-CLIA was from 0.975 to 1,000 ng/ml, while that of VtgC-CLIA was from 0.
View Article and Find Full Text PDFTranscription of vitellogenin (vtg) genes are initiated when estradiol-17β (E)-estrogen receptor (ER) complexes bind estrogen response elements (ERE) located in the gene promoter region. Transcriptional regulation of dual vtg subtypes (major salmonid A-type vtg: vtgAs; minor C-type vtg: vtgC) by E was investigated under co-expression of a potential major transcriptional factor, erα1, in cutthroat trout. Two forms of trout vtgAs promoters (1 and 2) and one vtgC promoter were sequenced.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
October 2017
To evaluate potential involvement of clathrin in endocytosis of vitellogenin (Vtg) by teleost oocytes, cDNAs encoding clathrin heavy chain (cltc) were cloned from ovaries of cutthroat trout. Quantitative PCR revealed three types of cltc (cltc-a1, cltc-a2, cltc-b) to be expressed in 10 different tissues including the ovary. The cltc-a1 alone exhibited a significant decrease in ovarian expression during vitellogenesis; this was correlated with a corresponding decrease in transcripts encoding the major Vtg receptor (Vtgr).
View Article and Find Full Text PDFJ Steroid Biochem Mol Biol
January 2017
One or more distinct forms of the nuclear estrogen receptor (ER) have been isolated from many vertebrates to date. To better understand the molecular evolution of ERs, we cloned and characterized er cDNAs from the inshore hagfish, Eptatretus burgeri, a modern representative of the most primitive vertebrates, the agnathans. Two er cDNAs, er1 and er2, were isolated from the liver of a reproductive female hagfish.
View Article and Find Full Text PDFPrimordial germ cells (PGCs) appear during early embryogenesis and differentiate into gametes through oogenesis or spermatogenesis. Teleost PGCs can be visualized by injecting RNA transcribed from the fusion product of a fluorescent protein gene attached to the 3' untranslated region (3'UTR) of zebrafish nanos3 (zf-nos3). Although this method has been widely applied to teleost PGCs, the visualization of PGCs in pelagic species that have eggs with a hard chorion is more problematic due to the technical difficulty of microinjection into their eggs.
View Article and Find Full Text PDFMultiple ovarian membrane proteins that bind vitellogenin (Vtg) have been detected in teleosts. One of these Vtg receptors was recently identified as low-density lipoprotein receptor-related protein 13 (lrp13/Lrp13) in perciform species, but little is known about this Vtg receptor in salmonid fish. In this study, a cDNA encoding a putative Vtg receptor with 13+1 ligand binding repeats (lr13+1) was cloned from the ovary, and identified as an lrp13 ortholog for cutthroat trout (Oncorhynchus clarki).
View Article and Find Full Text PDFFish egg yolk is largely derived from vitellogenins, which are synthesized in the liver, taken up from the maternal circulation by growing oocytes via receptor-mediated endocytosis and enzymatically processed into yolk proteins that are stored in the ooplasm. Lipid droplets are another major component of fish egg yolk, and these are mainly composed of neutral lipids that may originate from maternal plasma lipoproteins. This review aims to briefly summarize our current understanding of the molecular mechanisms underlying yolk formation in fishes.
View Article and Find Full Text PDFTranscripts encoding a novel member of the lipoprotein receptor superfamily, termed LDL receptor-related protein (Lrp)13, were sequenced from striped bass (Morone saxatilis) and white perch (Morone americana) ovaries. Receptor proteins were purified from perch ovary membranes by protein-affinity chromatography employing an immobilized mixture of vitellogenins Aa and Ab. RT-PCR revealed lrp13 to be predominantly expressed in striped bass ovary, and in situ hybridization detected lrp13 transcripts in the ooplasm of early secondary growth oocytes.
View Article and Find Full Text PDFCircadian rhythms are controlled by a system of negative and positive genetic feedback loops composed of clock genes. Although many genes have been implicated in these feedback loops, it is unclear whether our current list of clock genes is exhaustive. We have recently identified Chrono as a robustly cycling transcript through genome-wide profiling of BMAL1 binding on the E-box.
View Article and Find Full Text PDFVitellogenesis has been extensively studied in oviparous vertebrates, including teleost fishes, while not much is known with regard to jawless hagfishes, modern representatives of the most primitive vertebrate class. This study aimed to characterize vitellogenin (Vtg) and yolk protein (YP) in the inshore hagfish (Eptatretus burgeri) as an initial step to understand vitellogenesis in this species. A putative Vtg fraction was purified from the serum of female hagfish by combinations of hydroxylapatite and ion-exchange chromatography, followed by gel filtration.
View Article and Find Full Text PDFThe gene, vitellogenin (vtg) was cloned and characterized in the dojo loach (Misgurnus anguillicaudatus), an indigenous freshwater species in East Asia, in order to develop tools for detecting the effects of estrogenic endocrine-disrupting chemicals (EEDCs). Full-length cDNAs encoding seven distinct vtg transcripts (vtg1-7) were obtained. The corresponding deduced amino acid sequences (Vtg1-7) were divided into two types; type I (Vtg1-6; 89-99% identical), which contained both lipovitellin (Lv) and phosvitin (Pv), and type II (Vtg7), which contained Lv alone.
View Article and Find Full Text PDFDespite its key role in transportation of triacylglycerides in blood, the distribution, localisation and molecular weight variants of apolipoprotein B (Apob) in teleost fish have essentially escaped study. To address this, a specific short-finned eel (Anguilla australis) Apob antiserum was produced by an immunised rabbit, purified and partially characterised. Localisation of Apob at both the mRNA (in situ hybridisation) and protein (immunohistochemistry) levels mirrored that of mammals; thus immunostaining was confined to the interstitial spaces of the liver and the vascular core of the intestinal villi.
View Article and Find Full Text PDFComp Biochem Physiol B Biochem Mol Biol
September 2013
A cDNA encoding a vitellogenin receptor with 8 ligand binding repeats (vtgr) was cloned from ovaries of the cutthroat trout, Oncorhynchus clarki. In situ hybridization and quantitative PCR analyses revealed that the main site of vtgr mRNA expression was the oocytes. Expression was strongly detected in perinucleous stage oocytes, gradually decreased as oocytes grew, and became hardly detectable in vitellogenic oocytes.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
October 2013
Teleost fish eggs contain a substantial yolk mass consisting of lipids and proteins that provides essential nutrients for embryonic and larval development. The polar lipid and protein components of the yolk are delivered to oocytes by circulating vitellogenins, however the source(s) of the neutral lipid remains unknown. We cloned a cDNA encoding an orthologue of low-density-lipoprotein receptor (LDLR) from the ovary of cutthroat trout, Oncorhynchus clarki (ct-Ldlr).
View Article and Find Full Text PDFA single radial immunodiffusion (SRID) assay and a chemiluminescent immunoassay (CLIA) were initially developed for alpha-fetoprotein (AFP) of the striped dolphin. Utilizing these developed assays, we investigated pregnancy-associated changes in the levels of AFP in the sera of fetuses and pregnant females of three dolphin species; samples were either collected from captive individuals or obtained as fishery by-products. The concentrations of AFP in the fetal serum ranged from 419.
View Article and Find Full Text PDFLarge amounts of neutral lipids (NLs) are stored as lipid droplets in the ooplasm of fish oocytes, providing an essential energy resource for developing embryos and larvae. However, little is known about the origin of such lipids or about mechanisms underlying their uptake and accumulation in oocytes. We have proposed a model for this lipidation of teleost oocytes, as follows: very low density lipoprotein (Vldl) is metabolized by lipoprotein lipase (Lpl) outside and/or inside of the oocyte and the resulting fatty acids (FAs) are then utilized for de novo biosynthesis of NLs.
View Article and Find Full Text PDFElasmobranchs (sharks and rays) exhibit unique reproductive characteristics and, in contrast to the situation in teleosts, very little is known about the identity, structure and physical characteristics of their egg yolk proteins. The aims of this study were to (1) detect and purify the vitellogenin (Vtg; egg yolk precursor) and yolk proteins (YPs) of the cloudy catshark (Scyliorhinus torazame), (2) examine the relationships between Vtg and YPs and (3) characterize and classify the deduced primary structure of the Vtg transcript (vtg). The apparent molecular weights of purified Vtg and putative Vtg-related YPs (lipovitellin: Lv, phosvitin: Pv) were determined by gel filtration and were ~560, >669 and ~58 kDa, respectively.
View Article and Find Full Text PDFAlpha-fetoprotein (AFP) is a fetal glycoprotein that is known as a biomarker for monitoring pregnancy in many mammalian species. However, characterization of AFP has not yet been undertaken in any cetacean species. Here, we purified AFP from the serum of fetal striped dolphin by chemical precipitation followed by a combination of immunoadsorbent column chromatography and gel filtration.
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