Yolk Precursor Research Articles

Ectopic synthesis of vitellogenin in testis and epididymis of estrogen-treated lizard Podarcis sicula

In oviparous vertebrates, vitellogenin (VTG) is the major yolk precursor synthesized in the liver of sexually mature females during the reproductive period. In males, the VTG gene is silent, but it may be activated by estradiol-17β (E2) or estrogen-like substances. Until now, extra-hepatic expression and synthesis of VTG after estrogen exposure has been reported only for aquatic vertebrates. This study demonstrates the ability of testis and epididymis of the terrestrial oviparous lacertid Podarcis sicula to synthesize VTG following E2 exposure. The results of in situ hybridization and immunohistochemistry analysis show the presence of both VTG mRNA and protein in these districts besides the known induction in the liver. The possible contemporaneous uptake of the E2-induced hepatic VTG by means of the specific vitellogenin receptor has been also evaluated. Finally, histological analysis shows that the E2-treatment during the mating season impairs spermatogenesis.

Effects of Imidacloprid and Varroa destructor on survival and health of European honey bees, Apis mellifera.

There has been growing concern over declines in populations of honey bees and other pollinators which are a vital part to our food security. It is imperative to identify factors responsible for accelerated declines in bee populations and develop solutions for reversing bee losses. While exact causes of colony losses remain elusive, risk factors thought to play key roles are ectoparasitic mites Varroa destructor and neonicotinoid pesticides. The present study aims to investigate effects of a neonicotinoid pesticide Imidacloprid and Varroa mites individually on survivorship, growth, physiology, virus dynamics and immunity of honey bee workers. Our study provides clear evidence that the exposure to sublethal doses of Imidacloprid could exert a significantly negative effect on health and survival of honey bees. We observed a significant reduction in the titer of vitellogenin (Vg), an egg yolk precursor that regulates the honey bees development and behavior and often are linked to energy homeostasis, in bees exposed to Imidacloprid. This result indicates that sublethal exposure to neonicotinoid could lead to increased energy usage in honey bees as detoxification is a energy-consuming metabolic process and suggests that Vg could be a useful biomarker for measuring levels of energy stress and sublethal effects of pesticides on honey bees. Measurement of the quantitative effects of different levels of Varroa mite infestation on the replication dynamic of Deformed wing virus (DWV), an RNA virus associated with Varroa infestation, and expression level of immune genes yields unique insights into how honey bees respond to stressors under laboratory conditions.

Comprehensive and quantitative proteomic analyses of zebrafish plasma reveals conserved protein profiles between genders and between zebrafish and human.

Omic approaches have been increasingly used in the zebrafish model for holistic understanding of molecular events and mechanisms of tissue functions. However, plasma is rarely used for omic profiling because of the technical challenges in collecting sufficient blood. In this study, we employed two mass spectrometric (MS) approaches for a comprehensive characterization of zebrafish plasma proteome, i.e. conventional shotgun liquid chromatography-tandem mass spectrometry (LC-MS/MS) for an overview study and quantitative SWATH (Sequential Window Acquisition of all THeoretical fragment-ion spectra) for comparison between genders. 959 proteins were identified in the shotgun profiling with estimated concentrations spanning almost five orders of magnitudes. Other than the presence of a few highly abundant female egg yolk precursor proteins (vitellogenins), the proteomic profiles of male and female plasmas were very similar in both number and abundance and there were basically no other highly gender-biased proteins. The types of plasma proteins based on IPA (Ingenuity Pathway Analysis) classification and tissue sources of production were also very similar. Furthermore, the zebrafish plasma proteome shares significant similarities with human plasma proteome, in particular in top abundant proteins including apolipoproteins and complements. Thus, the current study provided a valuable dataset for future evaluation of plasma proteins in zebrafish.

A comparative study of vitellogenesis in Echinodermata: Lessons from the sea star

The provision of yolk precursor proteins to the oviparous egg is crucial for normal embryo development. In Echinodermata, a transferrin-like yolk component termed major yolk protein (MYP) is a major precursor protein in Echinoidea and Holothuroidea. In contrast, in Asteroidea a single vitellogenin (Vtg) was recently identified, but its role as primary yolk protein remains unclear. To resolve the apparent MYP-Vtg dichotomy in sea stars and to understand the dynamics of candidate yolk protein gene expression during the reproductive cycle, we investigated the molecular structures of sea star Vtg and MYP and quantified their transcript levels during oogenesis. By combining protein sequencing of the predominant proteins in ovulated eggs of Patiriella regularis with ovarian transcriptome sequencing and molecular cloning, we characterized two cDNAs encoding two bona fide Vtgs (PrVtg1 and PrVtg2) and a partial cDNA encoding MYP (PrMYP). PrMYP mRNA was found in low abundance in growing oocytes, possibly as maternal transcripts for translation after ovulation. In contrast, PrVtg transcripts, whose levels varied during the reproductive cycle, were not found in developing oocytes – rather, they were detected in ovarian follicle cells and pyloric caeca, indicating an extra-oocytic origin. Vtg accumulating in oocytes was stored in the form of cleaved products, which constituted the most abundant yolk polypeptides in ovulated sea star eggs; their levels decreased during early embryonic and larval development. Together, these traits are the hallmarks of a classical yolk protein – and hence, we contend that Vtg, and not MYP, is the main yolk protein in asteroids.

Identification and partial characterization of Olyra longicaudata (McClelland, 1842) vitellogenins: Seasonal variation in plasma, relative to estradiol-17β and ovarian growth

This study aims at immunochemical characterization of plasma vitellogenin (VTG), development of an heterlogous VTG ELISA and to relate seasonal variation in plasma VTG and estradiol-17β (E2) levels with ovarian growth (gonadosomatic index, GSI) in Olyra longicaudata (McClelland, 1842), a rare hill-stream catfish endemic to North East India. On native PAGE, plasma from E2-injected male, vitellogenic as well as gravid females, but not untreated male, resolved into two major protein bands. These two proteins stained positive for carbohydrate, lipid and phosphorous, albeit with differential intensity and cross-reacted well with catfish VTG antiserum (a-VTG) suggesting them as putative VTGs in circulation. Ammonium sulphate (50%) fractionation followed by SDS-PAGE analysis of E2-treated male plasma resolved into four protein bands (150–15kDa), of which two, with molecular mass of 150 and 130kDa cross-reacted with a-VTG indicating them as VTG monomers. Immunoprecipitation of E2-induced plasma and immunoblot analysis of crude yolk proteins with a-VTG revealed two proteins in each case indicating two forms of VTG, present in circulation, possibly act as yolk precursors. Competitive antigen-capture ELISA developed earlier for catfish, Clarias batrachus VTG (CF-VTG1), revealed parallel binding slopes between dilution curves of plasma from vitellogenic female, E2-treated male and CF-VTG1 standard. Congruent with gradual increase in plasma E2, ovarian weight and appearance of vitellogenic and yolky oocytes, VTG level in circulation increased sharply in May–June, reaching the peak value in July, dropped sharply during August–September and was undetected or negligible in amount during December allowing identification of the ripening, the pre-spawning, the spawning and the quiescent phases respectively.

Differential immune response of vitellogenin gene to Vibrio anguillarum in noble scallop Chlamys nobilis and its correlation with total carotenoid content.

Vitellogenin (Vg), an egg yolk precursor protein, not only functions as a source of nutrients and a nonpolar molecular carrier that combine and transfer lipids, proteins, vitamin and carotenoids to oocytes during the oogenesis. but also links with the immune defense in many oviparous animals. To investigate whether Vg plays a immune defensive role in noble scallop Chlamys nobilis, an acute Vibrio anguillarum infection experiment was conducted in orange and brown scallops with different carotenoids content. qRT-PCR result showed that Vg transcripts were significantly up-regulated after challenge with V. anguillarum in orange and brown shell scallops compared to the control group and Vg expression reached the highest spot at 6 h, indicated that Vg possessed an immune function in the noble scallop. Interestingly, a significantly positive correlation between Vg transcript levels and total carotenoids content in the ovary was observed, indicating that Vg gene expression was up regulated by carotenoids. The results suggest that Vg is a potent immune protector and carotenoid may linked with Vg plays an important role in host immune system against pathogens in noble scallop C. nobilis.

Age-dependent effects in fathead minnows from the anti-diabetic drug metformin

The anti-diabetic drug metformin is thought to be the pharmaceutical most deposited into the aquatic environment by mass at up to 6tons per year from individual WWTPs in urban areas. Recent studies have shown that exposure to 40ug/L of metformin increased the relative expression of the egg yolk precursor protein vitellogenin in adult male fathead minnows (Pimephales promelas) (FHM). For this study, the expression of several other genes involved in estrogen biosynthesis, clearance and downstream effects were assessed in FHM after treatment to three concentrations of metformin, to better understand the estrogenic effects of metformin on FHM. In contrast to the previous study, although upward trends were observed, metformin failed to significantly alter the expression of VTG, ERα, GnRH3, and CYP3A126 in adult male FHM. However, a concentration-dependent response to metformin was observed in younger 80–90day juvenile FHM. A 17.7-, 22-, and 22-fold increase in the relative expression of VTG mRNA in juvenile FHM exposed to 1, 10, and 100μg/L as compared to the control was observed. There was also a 3.3-, 4.7-, and 5.5-fold increase in GnRH3 in juvenile FHM exposed to 1, 10, and 100μg/L as compared to the control. Similarly, a 14-, 16-, and 24-fold increase in the relative expression of CYP3A126 mRNA was measured in juvenile FHM exposed to 1, 10 and 100μg/L metformin as compared to the control. These results indicate that juvenile FHM were more susceptible to the estrogenic effects of metformin during a 7-d exposure than older, sexually mature male FHM.

The association of very low-density lipoprotein receptor (VLDLR) haplotypes with egg production indicates VLDLR is a candidate gene for modulating egg production.

The very low-density lipoprotein receptor (VLDLR) transports egg yolk precursors into oocytes. However, our knowledge of the distribution patterns of VLDLR variants among breeds and their relationship to egg production is still incomplete. In this study, eight single nucleotide polymorphisms (SNPs) that account for 87% of all VLDLR variants were genotyped in Nick Chick (NC, n=91), Lohmann Brown (LohB, n=50) and Lueyang (LY, n=381) chickens, the latter being an Chinese indigenous breed. Egg production by NC and LY chickens was recorded from 17 to 50 weeks. Only four similar haplotypes were found in NC and LohB, of which two accounted for 100% of all NC haplotypes and 92.5% of LohB haplotypes. In contrast, there was considerable haplotypic diversity in LY. Comparison of egg production in LY showed that hens with NC-like haplotypes had a significantly higher production (p < 0.05) than those without the haplotypes. However, VLDLR expression was not significantly different between the haplotypes. These findings indicate a divergence in the distribution of VLDLR haplotypes between selected and non-selected breeds and suggest that the near fixation of VLDLR variants in NC and LohB is compatible with signature of selection. These data also support VLDLR as a candidate gene for modulating egg production.

Use of Vitellogenin as Biomarker Indicator in Sex Identification of Giant Grouper (Epinephelus lanceolatus)

Vitellogenin, the egg yolk precursor protein, has studied as biomarker for sex identification of giant grouper (Epinephelus lanceolatus). Vitellogenin was synthesized successfully in liver of male giant grouper by implanted with 2 mg/kg of Estradiol-17-s (E2). The levels of vitellogenin (vtg) in blood of E2-injected fish were comparable with those found in the blood of naturally male and female by observed with SDS-PAGE. With antigen from purified plasma E2-treated was produced polyclonal antibody of giant grouper after immunization process with rabbit for 72 days. Analyst by ELISA has demonstrated polyclonal antibody was developed within 2 weeks after primary immunization and greatest differences in absorbance at 1:8,000 dilutions. Validation by western blot, has verified vitellogenin as positive control (in female natural) and negative control (in male natural). It’s showed that the antigens vtg of giant grouper polyclonal antibody recognized the purified giant grouper vtg in natural female and treated estradiol male. The information on Vtg through this experiment could provide the basis of an immunological assay for sex identification and maturational status of the Giant grouper. Consequently, the aim of the present study was to establish a simple, efficient and non-lethal technique by using Vtg as biomarker indicator for rapid sex identification without killing or seriously injuring the sampled individuals.

Variability in Fish Tissue Proximate Composition is Consistent with Indirect Effects of Hypoxia in Chesapeake Bay Tributaries

AbstractThe spatial and temporal extent of summer hypoxia (dissolved oxygen [DO] concentration ≤ 2 mg/L) in Chesapeake Bay and its tributaries has been increasing for decades, consequently affecting fish distribution and abundance by shifting biomass to non‐hypoxic habitats. Hypoxia in coastal waters impacts food web dynamics, thereby limiting ecosystem productivity and affecting regional fisheries. Additionally, laboratory studies of Atlantic Croakers Micropogonias undulatus have shown that hypoxia serves as an endocrine disruptor, reducing the production of the yolk precursor vitellogenin as well as affecting other biochemical pathways. Reproductive potential is therefore lower in hypoxia‐exposed Atlantic Croakers than in fish that are taken from normoxic conditions. We examined field‐caught Atlantic Croakers from three Chesapeake Bay tributaries with different DO levels to evaluate patterns in the lipid content of somatic and gonadal tissues. We found that somatic lipid content was not affected by the presence of hypoxia, whereas ovarian lipid content was significantly affected by the severity of hypoxia. Furthermore, Atlantic Croakers that were exposed indirectly to mild hypoxia (lasting hours to days) exhibited greater ovarian lipid content than fish that were captured from normoxic sites. As expected, severe hypoxia reduced the ability of Atlantic Croakers to accumulate lipids in their ovaries, likely affecting reproductive output. Stock assessment models that ignore the effects of hypoxia may yield overly optimistic production estimates for hypoxia‐exposed populations, particularly if environmentally invariant fecundity and growth are assumed.Received December 16, 2014; accepted September 24, 2015

Quantification of X. laevis vitellogenin by liquid chromatography tandem mass spectrometry

Over the last several decades, there has been an increase in public awareness and regulatory activity in regard to the presence of emerging contaminants in the environment that may have the potential to interact with the endocrine system of exposed wildlife. Alterations in vitellogenin (VTG), a high density yolk precursor protein, can indicate endocrine activity in oviparous species, including many fish and amphibians. While various methodologies and experiments have been performed to characterize baseline VTG concentrations among commonly studied fish species, fewer methodologies for accurately quantifying amphibian VTG are available. Since there is relatively little information available on background VTG levels in male and female frogs, the present investigation set out to quantify baseline levels of VTG in juvenile as well as adult male and female African clawed frogs (Xenopus laevis) using a newly developed liquid chromatography tandem mass spectrometry method. This new methodology for quantifying VTG in X. laevis frog blood plasma can be applied in mechanistic and toxicity studies with X. laevis to better characterize potential endocrine modes of action.

Protein identification of vitellogenin in river catfish (&lt;i&gt;Hemibagrus nemurus&lt;/i&gt;)

Mass production of fish broodstock with high quality eggs requires the knowledge on the chemical composition and physiochemical properties of vitellogenin (Vtg) during ovulation. Vtg is an egg yolk precursor phospholipoglycoprotein, and has been analysed to evaluate the reproductive conditions and determine the spawning period in captive and wild fish. In this study, Vtg was induced in male H. nemurus through three intramuscular injections of 17- estradiol (E2). The Vtg was purified from the serum using gel filtration chromatography and thepurified protein was reduced via SDS-PAGE. One major polypeptide corresponding to 130 kDa was observed. Vtg identification was done using peptide mass fingerprint (PMF) from the trypsin digestion of male H. nemurus Vtg induced with E2. The sequence homology of H. nemurus AYLAGAAADVLEVGVR matched the Vtg of other fish species when analysedusing MALDI-TOF. Vtg was confirmed by MASCOT at 95% significant level. The potential protein that controls the reproductive process and oocyte development isolated from this study was discussed to understand the structure and function of Vtg.

Immune-Relevant and Antioxidant Activities of Vitellogenin and Yolk Proteins in Fish.

Vitellogenin (Vtg), the major egg yolk precursor protein, is traditionally thought to provide protein- and lipid-rich nutrients for developing embryos and larvae. However, the roles of Vtg as well as its derived yolk proteins lipovitellin (Lv) and phosvitin (Pv) extend beyond nutritional functions. Accumulating data have demonstrated that Vtg, Lv and Pv participate in host innate immune defense with multifaceted functions. They can all act as multivalent pattern recognition receptors capable of identifying invading microbes. Vtg and Pv can also act as immune effectors capable of killing bacteria and virus. Moreover, Vtg and Lv are shown to possess phagocytosis-promoting activity as opsonins. In addition to these immune-relevant functions, Vtg and Pv are found to have antioxidant activity, which is able to protect the host from oxidant stress. These non-nutritional functions clearly deepen our understanding of the physiological roles of the molecules, and at the same time, provide a sound basis for potential application of the molecules in human health.

Epigenetic and endocrine determinants of lifespan differences between the castes of social insects

Social insects are promising model organisms in the study of longevity mechanisms. They have a caste system, in which the same genomes may produce phenotypes significantly distinguished by longevity. The ontogenetic trajectories of bees depend on the duration of supply by a specific nutrient mixture (royal jelly) at the larval stage. Longer feeding by the royal jelly leads to the formation of the queen epigenome, which is different from the epigenome of a working bee. Such epigenetic differences, in turn, induce endocrine changes manifested in increased synthesis of juvenile hormone and activation of TOR (target of rapamycin) signaling pathway, as well as in the modulation of insulin/IGF-1 pathway in queen-destined larvae. In adults, these processes influence the synthesis of vitellogenin (egg yolk precursor determining many aspects of insect ontogenesis). Epigenetic and andocrine mechanisms that underlie differences in longevity among the castes of social insects are discussed.

Efficiency of advanced wastewater treatment technologies for the reduction of hormonal activity in effluents and connected surface water bodies by means of vitellogenin analyses in rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta f. fario).

Endocrine effects in the aquatic environment are in the focus of scientists and media along with debates on the necessity of further steps in wastewater treatment. In the present study VTG responses were compared to evaluate upgrades at wastewater treatment plants (WWTPs). We investigated several advanced sewage treatment technologies at two WWTPs connected to the Schussen, a tributary of Lake Constance, for the reduction of hormonal activity: (1) a powdered activated charcoal filter at the WWTP Langwiese; and (2) a combination of ozonation, sand filter, and granulated activated carbon filter at the WWTP Eriskirch. Rainbow trout and brown trout were either directly exposed to the effluents in aquaria or cages, or in a bypass system flown through by surface water of the Schussen. As a reference, trout were kept in bypass aquaria at the Argen River, which is less influenced by micropollutants. As a biomarker for estrogenicity, we analyzed the yolk precursor protein vitellogenin in immature rainbow trout and brown trout and in trout larvae (100 days post-fertilization) prior to and after the upgrade with the new technologies. Trout of different ages and species were used to detect differences in their sensitivity. At both bypass stations, larvae of brown trout showed significantly higher vitellogenin levels prior to the upgrade compared to negative control levels. Female brown trout exposed at the bypass station downstream of the WWTP showed decreased vitellogenin levels after the upgrade. In 1-year-old immature trout directly exposed to the respective effluents, no significant effects of the upgrades on vitellogenin levels were found. In general, larger effects were observed in brown trout than in rainbow trout, indicating that they are more sensitive test organisms.

Lipid transport to avian oocytes and to the developing embryo.

Studies of receptor-mediated lipoprotein metabolic pathways in avian species have revealed that physiological intricacies of specific cell types are highly analogous to those in mammals. A prime example for the power of comparative studies across different animal kingdoms, elucidated in the chicken, is that the expression of different lipoprotein receptors in somatic cells and oocytes are the key to oocyte growth. In avian species, yolk precursor transport from the hen's liver to rapidly growing oocytes and the subsequent transfer of yolk nutrients via the yolk sac to the developing embryo are highly efficient processes. Oocytes grow from a diameter of 5 mm to 2.5-3 cm in only 7 days, and the yolk sac transfers nutrients from the yolk stored in the mature oocyte to the embryo within just 2 weeks. The underlying key transport mechanism is receptor-mediated endocytosis of macromolecules, i.e., of hepatically synthesized yolk precursors for oocyte growth, and of mature yolk components for embryo nutrition, respectively. Recently, the receptors involved, as well as the role of lipoprotein synthesis in the yolk sac have been identified. As outlined here, lipoprotein degradation/resynthesis cycles and the expression of lipoprotein receptors are not only coordinated with the establishment of the follicular architecture embedding the oocyte, but also with the generation of the yolk sac vasculature essential for nutrient transfer to the embryo.

Vitellogenin and vitellogenin receptor gene expression is associated with male and female parenting in a subsocial insect.

Complex social behaviour in Hymenoptera has been hypothesized to evolve by co-opting reproductive pathways (the ovarian ground plan hypothesis, OGPH) and gene networks (the reproductive ground plan hypothesis, RGPH). In support of these hypotheses, in eusocial Hymenoptera where there is reproductive division of labour, the yolk precursor protein vitellogenin (Vg) influences the expression of worker social behaviour. We suggest that co-opting genes involved in reproduction may occur more generally than just in the evolution of eusociality; i.e. underlie earlier stages of social evolution such as the evolution of parental care, given that reproduction and parental care rarely overlap. We therefore examined vitellogenin (vg) gene expression associated with parental care in the subsocial beetle Nicrophorus vespilloides. We found a significant reduction in the expression of vg and its receptor, vgr, in head tissue during active parental care, and confirmed that the receptor is expressed in the brains of both sexes. Ours is the first study to show that vgr is expressed in the brain of a non-eusocial insect. Given the association between behaviour and gene expression in both sexes, and the presence of vitellogenin receptors in the brain, we suggest that Vg was co-opted early in the evolution of sociality to have a regulatory function. This extends the association of Vg in parenting to subsocial species and outside of the Hymenoptera, and supports the hypothesis that the OGPH is general and that heterochrony in gene expression is important in the evolution of social behaviour and precedes subsequent evolutionary specialization of social roles.

Machine learning reveals sex-specific 17β-estradiol-responsive expression patterns in white perch (Morone americana) plasma proteins.

With growing abundance and awareness of endocrine disrupting compounds (EDCs) in the environment, there is a need for accurate and reliable detection of EDC exposure. Our objective in the present study was to observe differences within and between the global plasma proteomes of sexually mature male and female white perch (Morone americana) before (Initial Control, IC) and after 17β-estradiol (E2 ) induction. Semiquantitative nanoLC-MS/MS data were analyzed by machine learning support vector machines (SVMs) and by two-way ANOVA. By ANOVA, the expression levels of 44, 77, and 57 proteins varied significantly by gender, treatment, and the interaction of gender and treatment, respectively. SVMs perfectly classified male and female perch IC and E2 -induced plasma samples using the protein expression data. E2 -induced male and female perch plasma proteomes contained significantly higher levels of the yolk precursors vitellogenin Aa and Ab (VtgAa, VtgAb), as well as latrophilin and seven transmembrane domain-containing protein 1 (Eltd1) and kininogen 1 (Kng1). This is the first report that Eltd1 and Kng1 may be E2 -responsive proteins in fishes and therefore may be useful indicators of estrogen induction.

Use of Immunofluorescence with Frozen Sections for the Detection of Vitellogenin Year-2 Class Natural Population Rainbow Trout-A Preliminary Investigation

Vitellogenin (VTG) is an egg yolk precursor protein produced in the liver in response to estrogen and is taken up by the oocytes of rainbow trout (Oncorhynchus mykiss) by receptor-mediated endocytosis. It is a useful biomarker which can be detected in blood plasma using an enzyme-linked-immunosorbent assay (ELISA) by using primary and secondary antibodies to detect the protein. This study utilized 12 juvenile male and female rainbow trout, to develop and test a new method as a hybrid of frozen section histology and ELISA to directly detect VTG within gonad tissue using immunofluorescence (IF). Frozen sections of gonads fluoresced bright yellow within Medium Stage IV cells, indicating the presence of VTG within the developing oocytes. Paraffin and frozen histology sections were also compared for efficacy and quality. The two methods produced similar results, however frozen sectioning was faster and the tissue was better preserved when viewed under the microscope. Paraffin provided excellent color contrast, but the tissue exhibited more damage when compared to the frozen sections. Use of frozen sections to examine morphology and IF to detect VTG in rainbow trout gonadal cells proved to be effective for analyzing VTG at the tissue level.

Estrogen-induced yolk precursors in European sea bass, Dicentrarchus labrax: Status and perspectives on multiplicity and functioning of vitellogenins

The estrogen-inducible egg yolk precursor, vitellogenin, of the European sea bass (Dicentrarchus labrax) has received considerable scientific attention by virtue of its central importance in determination of oocyte growth and egg quality in this important aquaculture species. However, the multiplicity of vitellogenins in the sea bass has only recently been examined. Recent cloning and homology analyses have revealed that the sea bass possesses the three forms of vitellogenin, VtgAa, VtgAb and VtgC, reported to occur in some other highly evolved teleosts. Progress has been made in assessing the relative abundance and special structural features of the three Vtgs and their likely roles in oocyte maturation and embryonic nutrition. This report discusses these findings in the context of our prior knowledge of vitellogenesis in this species and of the latest advances in our understanding of the evolution and function of multiple Vtgs in acanthomorph fishes.