ERβ Regulation of Indian Hedgehog Expression in the First Wave of Ovarian Follicles

Increased activation of ovarian primordial follicles in Erβ knockout (ErβKO) rats becomes evident as early as postnatal day 8.5. To identify the ERβ-regulated genes that may control ovarian primordial follicle activation, we analyzed the transcriptome profiles of ErβKO rat ovaries collected on postnatal days 4.5, 6.5, and 8.5. Compared to wildtype ovaries, ErβKO ovaries displayed dramatic downregulation of Indian hedgehog (Ihh) expression. IHH-regulated genes, including Hhip, Gli1, and Ptch1, were also downregulated in ErβKO ovaries. This was associated with a downregulation of steroidogenic enzymes Cyp11a1, Cyp19a1, and Hsd17b1. The expression of Ihh remained very low in ErβKO ovaries despite the high levels of Gdf9 and Bmp15, which are known upregulators of Ihh expression in the granulosa cells of activated ovarian follicles. Strikingly, the downregulation of the Ihh gene in ErβKO ovaries began to disappear on postnatal day 16.5 and recovered on postnatal day 21.5. In rat ovaries, the first wave of primordial follicles is rapidly activated after their formation, whereas the second wave of primordial follicles remains dormant in the ovarian cortex and slowly starts activating after postnatal day 12.5. We localized the expression of Ihh mRNA in postnatal day 8.5 wildtype rat ovaries but not in the age-matched ErβKO ovaries. In postnatal day 21.5 ErβKO rat ovaries, we detected Ihh mRNA mainly in the activated follicles in the ovaries' peripheral regions. Our findings indicate that the expression of Ihh in the granulosa cells of the activated first wave of ovarian follicles depends on ERβ.

Physiological and behavioral basis of diamondback moth Plutella xylostella migration and its association with heat stress

BACKGROUND

Migration is a strategy that shifts insects to more favorable habitats in response to deteriorating local environmental conditions. The ecological factors that govern insect migration are poorly understood for many species. Plutella xylostella causes great losses in Brassica vegetable and oilseed crops, and undergoes mass migration. However, the physiological and behavioral basis for distinguishing migratory individuals and the factors driving its migration remain unclear.

RESULTS

Daily light trap catches conducted from April to July in a field population of P. xylostella in central China revealed a sharp decline in abundance from late-May. Analysis of ovarian development levels showed that the proportion of sexually immature females gradually increased, while the mating rate decreased, indicating that generations occurring in May mainly resulted from local breeding and that emigration began in late-May. Physiological and behavioral analyses revealed that emigrant populations had a higher take-off proportion, stronger flight capacity and greater energy reserves of triglyceride compared to residents. Furthermore, a gradual increase in temperature from 24 °C to >30 °C during larval development resulted in a significant delay in oogenesis and increased take-off propensity of adults compared with the control treatment reared at a constant temperature of 24 °C.

CONCLUSION

Our results provide the physiological and behavioral factors that underpin mass migration in P. xylostella, and demonstrate that exposure to increased temperature increases their migration propensity at the cost of reproductive output. This study sheds light on understanding the factors that influence population dynamics, migratory propensity and reproductive tradeoffs in migratory insects. © 2023 Society of Chemical Industry.

Vitamin D3 promotes fish oocyte development by directly regulating gonadal steroid hormone synthesis†

Vitamin D receptors and vitamin D3-metabolizing enzymes have been found to be highly expressed in the ovaries and spermatophores of fish. However, the role of vitamin D3 on fish gonadal development has rarely been reported. In this study, 2-month-old female zebrafish were fed with different concentrations of vitamin D3 diets (0, 700, 1400, and 11 200 IU/kg) to investigate the effects of vitamin D3 on ovarian development. The diet with 0 IU/kg vitamin D3 resulted in elevated interstitial spaces, follicular atresia, and reproductive toxicity in zebrafish ovaries. Supplementation with 700 and 1400 IU/kg of vitamin D3 significantly increased the oocyte maturation rate; upregulated ovarian gonadal steroid hormone synthesis capacity; and elevated plasma estradiol, testosterone, and ovarian vitellogenin levels. Furthermore, the current study identified a vitamin D response element in the cyp19a1a promoter and demonstrated that 1.25(OH)2D3-vitamin D response directly activated cyp19a1a production through activating the vitamin D response element. In conclusion, this study shows that an appropriate concentration of vitamin D3 can promote zebrafish ovarian development and affect vitellogenin synthesis through the vdr/cyp19a1a/er/vtg gene axis.

A Human Homozygous HELQ Missense Variant Does Not Cause Premature Ovarian Insufficiency in a Mouse Model

Disruption of meiosis and DNA repair genes is associated with female fertility disorders like premature ovarian insufficiency (POI). In this study, we identified a homozygous missense variant in the HELQ gene (c.596 A>C; p.Gln199Pro) through whole exome sequencing in a POI patient, a condition associated with disrupted ovarian function and female infertility. HELQ, an enzyme involved in DNA repair, plays a crucial role in repairing DNA cross-links and has been linked to germ cell maintenance, fertility, and tumour suppression in mice. To explore the potential association of the HELQ variant with POI, we used CRISPR/Cas9 to create a knock-in mouse model harbouring the equivalent of the human HELQ variant identified in the POI patient. Surprisingly, Helq knock-in mice showed no discernible phenotype, with fertility levels, histological features, and follicle development similar to wild-type mice. Despite the lack of observable effects in mice, the potential role of HELQ in human fertility, especially in the context of POI, should not be dismissed. Larger studies encompassing diverse ethnic populations and alternative functional approaches will be necessary to further examine the role of HELQ in POI. Our results underscore the potential uncertainties associated with genomic variants and the limitations of in vivo animal modelling.

Rainfall during the night can trigger non-migratory take-off behavior of the white-backed planthopper, Sogatella furcifera

Take-off behavior is crucial to the overall success of insect migration. Although most high-altitude migratory flights commence with mass take-offs around dusk and dawn, little is known about nighttime take-off behavior. The take-off behavior of migratory Sogatella furcifera was investigated in field cages from 2017 to 2019. The species showed a bimodal take-off pattern at dusk and dawn on rainless nights, with mass flight at dusk more intense than dawn flight. However, a higher frequency of take-offs during the nighttime was observed on rainy nights, resulting in the absence of dawn take-offs. Most migratory take-off individuals at dusk and dawn landed on the cage top or the walls above 150 cm, while non-migratory individuals that took off during the nighttime due to rainfall mainly landed on the cage walls below 150 cm. Furthermore, it has been observed that migratory take-off individuals possess stronger sustained flight capabilities and exhibit more immature ovaries compared with non-migratory take-offs. These findings advance our understanding of the take-off behavior of S. furcifera and thus provide a basis for the accurate prediction and management of the migratory dynamics of this pest.

Characterizing the seasonal abundance and reproductive activity of overwintering Anopheles (Diptera: Culicidae) mosquitoes

In temperate regions of the United States, female Anopheles mosquitoes respond to low temperatures and short photoperiods by entering an overwintering dormancy or diapause. Diapause in Anopheles results in reduced frequency of blood-feeding and reproductive arrest, indicating a period when pathogen transmission by these mosquitoes is unlikely. However, it is unclear precisely how late into the fall and how early in the spring these mosquitoes are biting, reproducing, and potentially transmitting pathogens. This is further complicated by the lack of clear markers of diapause in Anopheles (e.g., changes in egg follicle length). Our goal was to characterize the seasonal reproductive activity of female Anopheles in central Ohio, United States and evaluate egg follicle length as an indicator of Anopheles diapause. We used traditional mosquito traps and aspirators to collect Anopheles from urban woodlots and culverts, respectively, from late September 2021 through mid-May 2022 in central Ohio. By measuring their egg follicle length, reproductive status, and blood-feeding status, we found that egg follicle length is not a reliable indicator of Anopheles diapause. We also found that a small proportion of An. punctipennis (Say), An. perplexens (Ludlow), and An. quadrimaculatus (Say) continued to bite and reproduce into early November 2021 and that females of these species terminated reproductive dormancy and began biting by mid-March 2022. This period of reproductive activity extends beyond current mosquito surveillance and control in Ohio. Our findings suggest that within temperate regions of North America, Anopheles have the capacity to transmit pathogens throughout the spring, summer, and fall.

Molecular Characterization, Expression Pattern, DNA Methylation and Gene Disruption of Figla in Blotched Snakehead (Channa maculata)

Figla is one of the earliest expressed genes in the oocyte during ovarian development. In this study, Figla was characterized in C. maculata, one of the main aquaculture species in China, and designated as CmFigla. The length of CmFigla cDNA was 1303 bp, encoding 197 amino acids that contained a conserved bHLH domain. CmFigla revealed a female-biased expression patterns in the gonads of adult fish, and CmFigla expression was far higher in ovaries than that in testes at all gonadal development stages, especially at 60~180 days post-fertilization (dpf). Furthermore, a noteworthy inverse relationship was observed between CmFigla expression and the methylation of its promoter in the adult gonads. Gonads at 90 dpf were used for in situ hybridization (ISH), and CmFigla transcripts were mainly concentrated in oogonia and the primary oocytes in ovaries, but undetectable in the testes. These results indicated that Figla would play vital roles in the ovarian development in C. maculata. Additionally, the frame-shift mutations of CmFigla were successfully constructed through the CRISPR/Cas9 system, which established a positive foundation for further investigation on the role of Figla in the ovarian development of C. maculata. Our study provides valuable clues for exploring the regulatory mechanism of Figla in the fish ovarian development and maintenance, which would be useful for the sex control and reproduction of fish in aquaculture.

Genome-Wide Identification of Vitellogenin Gene Family and Comparative Analysis of Their Involvement in Ovarian Maturation in Exopalaemon carinicauda

Vitellogenin (Vtg) is a precursor of yolk proteins in egg-laying vertebrates and invertebrates and plays an important role in vitellogenesis and embryonic development. However, the Vtg family remains poorly characterized in Exopalaemon carinicauda, a major commercial mariculture species found along the coasts of the Yellow and Bohai Seas. In this study, 10 Vtg genes from the genomes of E. carinicauda were identified and characterized. Phylogenetic analyses showed that the Vtg genes in crustaceans could be classified into four groups: Astacidea, Brachyra, Penaeidae, and Palaemonidae. EcVtg genes were unevenly distributed on the chromosomes of E. carinicauda, and a molecular evolutionary analysis showed that the EcVtg genes were primarily constrained by purifying selection during evolution. All putative EcVtg proteins were characterized by the presence of three conserved functional domains: a lipoprotein N-terminal domain (LPD_N), a domain of unknown function (DUF1943), and a von Willebrand factor type D domain (vWD). All EcVtg genes exhibited higher expression in the female hepatopancreas than in other tissues, and EcVtg gene expression during ovarian development suggested that the hepatopancreas is the main synthesis site in E. carinicauda. EcVtg1a, EcVtg2, and EcVtg3 play major roles in exogenous vitellogenesis, and EcVtg3 also plays a major role in endogenous vitellogenesis. Bilateral ablation of the eyestalk significantly upregulates EcVtg mRNA expression in the female hepatopancreas, indicating that the X-organ/sinus gland complex plays an important role in ovarian development, mostly by inducing Vtg synthesis. These results could improve our understanding of the function of multiple Vtg genes in crustaceans and aid future studies on the function of EcVtg genes during ovarian development in E. carinicauda.

Temporal and Spatial Signatures of Scylla paramamosain Transcriptome Reveal Mechanistic Insights into Endogenous Ovarian Maturation under Risk of Starvation

Variability in food availability leads to condition-dependent investments in reproduction. This study is aimed at understanding the metabolic response and regulatory mechanism of female Scylla paramamosain in response to starvation in a temporal- and tissue-specific manner. The mud crabs were starved for 7 (control), 14, 28, and 40 days for histological and biochemical analysis in the hepatopancreas, ovary, and serum, as well as for RNA sequencing on the hepatopancreas and ovary. We further highlighted candidate gene modules highly linked to physiological traits. Collectively, our observations suggested that starvation triggered endogenous ovarian maturation at the expense of hepatopancreas mass, with both metabolic adjustments to optimize energy and fatty acid supply from hepatopancreas to ovary in the early phase, followed by the activation of autophagy-related pathways in both organs over prolonged starvation. These specific adaptive responses might be considered efficient strategies to stimulate ovarian maturation of Scylla paramamosain under fasting stress, which improves the nutritional value of female mud crabs and other economically important crustaceans.

Reproductive biology of the electric lanternfish Electrona risso (Myctophidae) and the bigscale fishes Melamphaes polylepis and Scopelogadus mizolepis (Melamphaidae)

This study was the first to investigate the key reproductive traits of the electric lantern fish Electrona risso (Myctophidae, n = 918) and the bigscale fishes (Melamphaidae) Melamphaes polylepis (n = 260) and Scopelogadus mizolepis (n = 649). Specimens of these mesopelagic species were collected in March and April 2015 in the eastern Central Atlantic (0-24° N, 20-26° W). Sex ratio was not significantly different from 1:1 in E. risso and M. polylepis but significantly skewed toward female dominance in S. mizolepis. Reproductive phases were determined macroscopically and by histological analyses on selected individuals. Female length at 50% maturity (L50 ) was 55.1 mm standard length (LS ) in E. risso, with an observed female maximum length (Lmax ) of 81.2 mm LS . M. polylepis females had an L50 of 40.2 mm LS and an Lmax of 86.7 mm LS . S. mizolepis had an L50 of 46 mm LS and an Lmax of 97.9 mm LS . The three species show histological features of iteroparity, but the E. risso population appears to occur in two year-classes and experience only one spawning season per lifetime in the study region. All three species are batch-spawners. A batch fecundity of 2668 eggs was estimated from one E. risso individual, with a relative batch fecundity of 369 eggs g-1 gonad-free body mass. M. polylepis had a batch fecundity of 1027 eggs and a relative batch fecundity of 149 eggs g-1 (n = 3). S. polylepis had a batch fecundity of 1545 eggs and a relative batch fecundity of 215 eggs g-1 (n = 21). The median gonado-somatic index during the actively spawning phase of E. risso was 4.5, significantly lower than that of M. polylepis (7.5) and S. mizolepis (7.1). No regressing or regenerating phases were observed in this study. Batch-spawning in all three species is suggested to be advantageous to cope with intra-annual variability in food supply and other risks for offspring survival. With what appears to be in effect a (facultative) semelparous strategy in combination with a short life span in E. risso, interannual differences would have a great effect on population dynamics of this species. Knowledge is still lacking on temporal aspects of reproduction such as the duration of the spawning season and the frequency of spawning, as well as age and growth.

Effects of larval diets on some biological parameters and morphometric and biochemical analysis of ovaries of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

The effects of three larval diets (beef meat, chicken meat, and beef liver) on development of Lucilia cuprina (Wiedemann) were evaluated. Egg hatching rates were higher on chicken meat and beef meat (99.5%) than on beef liver (96.5%). Pupation success was higher on chicken meat (99.0%) and beef meat (98.0%) than on beef liver (87.1%). Adult emergence rates were higher in flies reared on chicken meat (99.0%) and beef meat (98.5%) than on beef liver (93.5%). Proportions of female flies were somewhat higher in flies reared on chicken meat or beef meat (54-56% female) than on beef liver (52.5%). Flies that were reared on chicken meat and beef meat had shorter egg-adult development times (16.3 days) than flies reared on beef liver (18.5 days), and the generation time of flies reared on chicken meat or beef meat (51-52 days) was several days shorter than flies reared on beef liver (54 days). Flies reared on chicken meat had larger ovaries and more ovarioles per ovary when larvae were reared on chicken than flies reared on beef meat or beef liver. The ovaries of flies reared on chicken meat had significantly higher amounts of protein (21 mg/g body weight) than flies reared on beef liver (12 mg). Analysis of the larval diets showed that beef liver had the lowest amounts of protein and carbohydrate of the three tested diets, whereas the amounts of lipids did not differ among the diets.

Spatio-temporal patterns of ovarian development and VgR gene silencing reduced fecundity in parthenogenetic Artemia

The halophilic zooplankton brine shrimp Artemia has been used as an experimental animal in multidisciplinary studies. However, the reproductive patterns and its regulatory mechanisms in Artemia remain unclear. In this study, the ovarian development process of parthenogenetic Artemia (A. parthenogenetica) was divided into five stages, and oogenesis or egg formation was identified in six phases. The oogenesis mode was assumed to be polytrophic. We also traced the dynamic translocation of candidate germline stem cells (cGSCs) using EdU labelling and elucidated several key cytological events in oogenesis through haematoxylin and eosin staining and fluorescence imaging. Distinguished from the ovary structure of insects and crustaceans, Artemia germarium originated from ovariole buds and are located at the base of the ovarioles. RNA-seq based on five stages of ovarian development identified 2657 upregulated genes related to reproduction by pair-to-pair comparison. Gbb, Dpp, piwi, vasa, nanos, VgA and VgR genes associated with cGSCs recognition and reproductive development were screened and verified using qPCR. Silencing of the VgR gene in A. parthenogenetica (Ap-VgR) at ovarian development Stage II led to a low level of gene expression (less than 10%) within 5 days, which resulted in variations in oogenesis-related gene expression and significantly inhibited vitellogenesis, impeded oocyte maturation, and eventually decreased the number of offspring. In conclusion, we have illustrated the patterns of ovarian development, outlined the key spatio-temporal features of oogenesis and identified the negative impacts of VgR gene knockdown on oogenesis using A. parthenogenetica as an experimental animal. The findings of this study also lay a foundation for the further study of reproductive biology of invertebrates.

Matrix metalloproteinase 2 degrades collagen I to regulate ovarian development by association with an insulin-like peptide

The ovary generally undergoes tissue remodeling during larval to pupal transition, which includes membrane degeneration and ovariole growth. At the same time, the hormones produced by insects significantly change during metamorphosis. However, the regulatory mechanism for ovarian development and hormones is not fully understood in insects. Herein, we found that matrix metalloproteinase 2 (MMP2) was highly expressed in the ovarian capsules and ovarioles, and the development was abnormal after knocking out MMP2 in Bombyx mori. The process of abnormal degradation of collagen I due to MMP2 deletion, which resulted in abnormal development of ovarioles and eggs, was analyzed in detail. The proteomics of ovaries in the MMP2-knock out and wild type strains showed a critically significant difference in the expression of a protein, insulin-like peptide (ILP). Additional analysis revealed significant alteration of ILP during ovarian development, and abnormal expression of ILP significantly affected ovarian development in vivo and MMP2 expression in vitro and in vivo. These results showed that MMP2 regulation of ovarian tissue remodeling is closely related to ILP expression. Our study provides new insights into the regulatory mechanism of MMP2 and ovarian development in B. mori.

Nutrient Composition of Ovary, Hepatopancreas and Muscle Tissues in Relation to Ovarian Development Stage of Female Swimming Crab, Portunus trituberculatus

The swimming crab Portunus trituberculatus is one of the most important economic species in China and its mature ovary often determines its commercial value and production. Although the ovary maturation of crustaceans is generally affected by exogenous nutrition, the specific nutritional needs of ovary maturation of P. trituberculatus are poorly understood. To this end, we collected the P. trituberculatus samples with five ovarian maturation stages and measured their biochemical composition of the ovary, hepatopancreas, and muscle at each ovarian developmental stage. We further analyzed their relation to the ovarian developmental stage of P. trituberculatus by principal components analysis (PCA). We found the levels of branched-chain amino acids, long-chain polyunsaturated fatty acids (LC-PUFA), and monounsaturated fatty acids (MUFAs) in the ovary and hepatopancreas increased during the ovary maturation process, and also passively correlated with ovarian developmental stage, which highlights the necessity of these specific nutrients for oogenesis and for improving the nutrient quality of crabs. In addition, we found an increasing tendency of carotenoid content and phosphatidylcholine in phospholipid in the ovary from the pre-developmental stage to the proliferative stage, but not in the hepatopancreas and muscle, which highlights the possible involvement of carotenoids during the rapid oocyte development process. Our study may provide valuable information for developing a suitable broodstock diet that promotes the ovarian maturation of adult P. trituberculatus and ensures high-quality larval production.

Establishment of cell-lines stably expressing recombinant Japanese eel follicle-stimulating hormone and luteinizing hormone using CHO-DG44 cells: fully induced ovarian development at different modes

The gonadotropins (Gth), follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh), play central roles in gametogenesis in vertebrates. However, available information on their differential actions in teleost, especially in vivo, is insufficient. In this study, we established stable CHO-DG44 cell lines expressing long-lasting recombinant Japanese eel Fsh and Lh with extra O-glycosylation sites (Fsh-hCTP and Lh-hCTP), which were produced in abundance. Immature female eels received weekly intraperitoneal injections of Gths. Fsh-hCTP induced the entire ovarian development by 8 weeks from the beginning of injection; thus, the ovaries of most fish were at the migratory nucleus stage while the same stage was observed in eels after 4 weeks in the Lh-hCTP-treated group. In contrast, all pretreated and saline-injected eels were in the pre-vitellogenic stage. Gonadosomatic indices in the Fsh-hCTP-treated group were significantly higher than those in the Lh-hCTP group at the migratory nucleus stage because of the significantly higher frequency of advanced ovarian follicles. Ovarian mRNA levels of genes related to E2 production (cyp11a1, cyp17a1, cyp19a1, hsd3b, fshr, and lhr) were measured using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). All genes were induced by both Fsh-hCTP and Lh-hCTP, with a peak at either the mid- or late vitellogenic stages. Transcript abundance of cyp19a1 and fshr in the Lh-hCTP group were significantly higher than those in the Fsh-hCTP group, whereas no difference in the expression of other genes was observed between the groups. Fluctuations in serum levels of sex steroid hormones (estradiol-17β, 11-ketotestosterone, and testosterone) in female eels were comparable in the Fsh-hCTP and Lh-hCTP groups, thus increasing toward the maturational phase. Furthermore, the fecundity of the eels induced to mature by Fsh-hCTP was significantly higher than that induced by Lh-hCTP. These findings indicate that Fsh and Lh can induce ovarian development in distinctively different modes in the Japanese eel.

Vitamin E Ameliorates Impaired Ovarian Development, Oxidative Stress, and Disrupted Lipid Metabolism in Oreochromis niloticus Fed with a Diet Containing Olive Oil Instead of Fish Oil

Aquaculture feed containing olive oil (OO) instead of fish oil (FO) can cause oxidative stress and impair gonad development in fish. We determined the effect of dietary OO-induced oxidative stress on ovarian development, and explored whether vitamin E (VE) could mitigate negative effects. Female Nile tilapia (Oreochromis niloticus) were fed for 10 weeks with four diets: 5% OO + 70 mg/kg VE, 5% OO + 200 mg/kg VE, 5% FO + 70 mg/kg VE, or 5% FO + 200 mg/kg VE. Dietary OO reduced the specific growth rate and gonadosomatic index, inhibited superoxide dismutase and catalase, delayed ovarian development, decreased serum sex hormone levels, and reduced ovarian triglyceride and n-3 highly unsaturated fatty acid contents. The transcript levels of genes encoding sex hormone receptors (erα, fshr, lhr) and components of the lipid metabolism pathway (pparα, pparγ, hsl, accα, elovl6), the nrf2 signaling pathway (nrf2, keap1), and the nf-κb signaling pathway (nf-κb, tnfα, infγ, il1β) differed between the 70VE/OO and 70VE/FO groups. Supplementation with 200 mg/kg VE mitigated the adverse effects of OO by improving antioxidant capacity and alleviating inflammation and abnormal lipid metabolism. This may be because VE is an antioxidant and it can regulate the nrf2-nf-κb signaling pathway.

Effects of supplemental nutrients on ovarian development and oviposition in Conogethes punctiferalis (Lepidoptera: Crambidae)

Conogethes punctiferalis is a serious pest in China affecting a wide variety of field crops, fruits, and forest trees. Many insects require supplemental nutrients after emergence to compensate for insufficient nutrients at the larval stage. In this study, to better understand the determinants of C. punctiferalis survival and reproduction, the impact of supplemental nutrition was examined. In particular, the effects of 11 treatments (5% sucrose, 10% sucrose, 15% sucrose, 5% sophora honey, 10% sophora honey, 15% sophora honey, 5% wild honey, 10% wild honey, 15% wild honey, distilled water, and blank control) on adult longevity and oviposition were evaluated, with detailed morphological analyses of ovarian development in the 10% sucrose, distilled water, and blank control groups. Conogethes punctiferalis required supplementary nutrition after emergence. Supplementary nutrition improved fecundity (number of eggs laid) and longevity, and 10% sucrose water had the greatest effects. The preoviposition period and oviposition period of C. punctiferalis females were longer, and the numbers of eggs in female ovarian tubes and eggs laid by females were higher in the 10% sucrose water group than in other groups. Females supplemented with distilled water laid a small number of eggs. Without nutrient supplementation, females did not lay eggs. In conclusion, supplemental nutrition was beneficial for ovarian development in female moths, prolonging the oviposition period and lifespan, and was an important factor affecting population dynamics. These results lay a foundation for further analyses of the nutritional requirements for C. punctiferalis in the field and provide a reference for indoor population feeding.

The role of Hippo pathway in ovarian development

The follicle is the functional unit of the ovary, whereby ovarian development is largely dependent on the development of the follicles themselves. The activation, growth, and progression of follicles are modulated by a diverse range of factors, including reproductive endocrine system and multiple signaling pathways. The Hippo pathway exhibits a high degree of evolutionary conservation between both Drosophila and mammalian systems, and is recognized for its pivotal role in regulating cellular proliferation, control of organ size, and embryonic development. During the process of follicle development, the components of the Hippo pathway show temporal and spatial variations. Recent clinical studies have shown that ovarian fragmentation can activate follicles. The mechanism is that the mechanical signal of cutting triggers actin polymerization. This process leads to the disruption of the Hippo pathway and subsequently induces the upregulation of downstream CCN and apoptosis inhibitors, thereby promoting follicle development. Thus, the Hippo pathway plays a crucial role in both the activation and development of follicles. In this article, we focused on the development and atresia of follicles and the function of Hippo pathway in these processes. Additionally, the physiological effects of Hippo pathway in follicle activation are also explored.

Pannier is a key regulator of embryogenesis, pupal development and female reproduction in the insect pest Bactrocera dorsalis

BACKGROUND

Most arthropods are famous for their large reproductive capacity, with the ovary playing a vital role in the process. The study of the regulatory mechanisms of ovarian development may have the potential for a reproduction-based pest management strategy. GATA-binding transcription factors (GATAs) as important regulatory factors mediate many physiological processes, including development, immunity, insecticide resistance and reproduction. The Pannier (pnr), a member of GATA family, was confirmed to be involved in ovarian development of Bactrocera dorsalis in our previous study. However, the direct evidence of pnr regulating the fly ovarian development is still lacking.

RESULTS

We used CRISPR/Cas9 to create Bdpnr loss-of-function mutations. Homozygous Bdpnr^-/- mutants were nonviable, with most individuals dying during embryogenesis, some surviving to the larval stages, and the remaining few dying during pupation. In contrast, heterozygous individuals reached the adult stage, but ovarian development was disrupted, with concomitant decreases in egg laying and hatching rates. We also found that two genes encoding vitellogenin proteins (BdVg1 and BdVg2) and the vitellogenin receptor (BdVgR) were significantly down-regulated in heterozygous mutants compared to wild-type controls.

CONCLUSION

These results indicate that Bdpnr is required for embryonic and post-embryonic development, including the formation of ovaries. Bdpnr could therefore be considered as a molecular target for tephritid fly pest control. © 2022 Society of Chemical Industry.

Choline supplementation regulates gut microbiome diversity, gut epithelial activity, and the cytokine gene expression in gilts

Choline is an essential nutrient that is necessary for both fetal development and maintenance of neural function, while its effect on female ovarian development is largely unexplored. Our previous study demonstrated that choline supplementation promotes ovarian follicular development and ovulation, although its underlying mechanism was unclear. To uncover the potential regulation pathway, eighteen female Yorkshire × Landrace gilts were fed with either standard commercial diet (Control group, n = 9) or choline supplemented diet (Choline group, additional 500 mg/kg of control diet, n = 9) from day 90 of age to day 186. At day 186, feces samples were analyzed for effects on the gut microbiome using 16S ribosomal RNA gene V3-V4 region sequencing with Illumina MiSeq, serum samples were analyzed for trimethylamine (TMA) and trimethylamine-N-oxide (TMAO) using HILIC method, and jejunum tissues were analyzed for immune related gene expression using qRT-PCR. Our results show that choline supplementation did not alter the circulating level of TMA and TMAO (P > 0.05), but rather increased gut microbiome alpha diversity (P < 0.05). Beta diversity analysis results showed that the choline diet mainly increased the abundance of Firmicutes, Proteobacteria, and Actinobacteria, but decreased the abundance of Bacteroidetes, Spirochaetes, and Euryarchaeota at the phyla level. Meta-genomic analysis revealed that choline supplementation activated pathways in the gut microbiota associated with steroid hormone biosynthesis and degradation of infertility-causing environmental pollutants (bisphenol, xylene, and dioxins). To further verify the effect of choline on intestinal activity, a porcine intestine cell line (IPEC-J2) was treated with serial concentrations of choline chloride in vitro. Our data demonstrated that choline promoted the proliferation of IPEC-J2 while inhibiting the apoptotic activity. qRT-PCR results showed that choline significantly increased the expression level of Bcl2 in both IPEC-J2 cells and jejunum tissues. The expression of IL-22, a cytokine that has been shown to impact ovarian function, was increased by choline treatment in vitro. Our findings reveal the beneficial effect of choline supplementation on enhancing the gut microbiome composition and intestinal epithelial activity, and offer insights into how these changes may have contributed to the ovarian development-promoting effect we reported in our previous study.

Characterizing oogenesis and programmed cell death in the eastern tree hole mosquito Aedes (Protomacleaya) triseriatus

Oogenesis in flies manifests as a carefully orchestrated cascade of developmental gates and growth events, punctuated by programmed cell death (PCD) and follicular resorption events. In anautogenous mosquitoes, a blood meal stimulates growth of primary follicles, but the timing of developmental stages is species-specific, and few species have been characterized. Here, we characterize the first gonotrophic cycle of oogenesis in Aedes triseriatus (Diptera: Culicidae), the principal vector of La Crosse Virus (LACV), a major cause of pediatric encephalitis in North America. We note significant differences in the timing and appearance of developmental stages from previous studies of other mosquito species, particularly Aedes aegypti. We also describe the appearance and timing of PCD events including atresia, nurse cell death, and follicular epithelium death and show that the majority of follicular epithelium cells do not undergo apoptosis during oogenesis but persist in the ovariole at least until the second gonotrophic cycle. This thorough characterization of oogenesis and PCD in Ae. triseriatus, through which LACV must persist in order to achieve filial infection, also serves as a baseline to study host-pathogen interactions during transovarial transmission.

Identification of differentially expressed genes and signaling pathways in Gaoyou duck ovary at different physiological stages

Introduction

Gaoyou duck is famous in China and abroad for its good production of double-yolk eggs. However, there has been no systematic research on the egg-laying characteristics of the Gaoyou duck, which limits the development and utilization of breed resource.

Methods

To identify the essential genes related to ovarian development, the transcriptome profiles of the ovaries of Gaoyou ducks at different physiological stages were analyzed. The transcriptome profiles of the ovaries of Gaoyou ducks at 150 d (before laying), 240 d (egg laying) and 500 d (nesting) were constructed, and the differentially expressed genes (DEGs) underwent GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses.

Results

The 6 randomly selected DEGs were verified by real-time fluorescent quantitative PCR that their relative expression was consistent with the transcriptional expression profile. Furthermore, KEGG analysis found that 8 candidate signaling pathways were essential for ovarian development, including the MAPK signaling pathway, Progesterone-mediated oocyte maturation, Cell adhesion molecules (CAMs), NOD-like receptor signaling pathway, ECM-receptor interaction, Focal adhesion, TGF-beta signaling path-way and Phagosome. Finally, 5 key DEGs were identified to participate in ovarian development, including TGIF1, TGFBR2, RAF1, PTK2 and FGF10.

Discussion

Our findings reveal the mechanisms under-lying the molecular regulation of related genes in Gaoyou duck ovarian development.

Application of Single-Cell RNA Sequencing in Ovarian Development

The ovary is a female reproductive organ that plays a key role in fertility and the maintenance of endocrine homeostasis, which is of great importance to women's health. It is characterized by a high heterogeneity, with different cellular subpopulations primarily containing oocytes, granulosa cells, stromal cells, endothelial cells, vascular smooth muscle cells, and diverse immune cell types. Each has unique and important functions. From the fetal period to old age, the ovary experiences continuous structural and functional changes, with the gene expression of each cell type undergoing dramatic changes. In addition, ovarian development strongly relies on the communication between germ and somatic cells. Compared to traditional bulk RNA sequencing techniques, the single-cell RNA sequencing (scRNA-seq) approach has substantial advantages in analyzing individual cells within an ever-changing and complicated tissue, classifying them into cell types, characterizing single cells, delineating the cellular developmental trajectory, and studying cell-to-cell interactions. In this review, we present single-cell transcriptome mapping of the ovary, summarize the characteristics of the important constituent cells of the ovary and the critical cellular developmental processes, and describe key signaling pathways for cell-to-cell communication in the ovary, as revealed by scRNA-seq. This review will undoubtedly improve our understanding of the characteristics of ovarian cells and development, thus enabling the identification of novel therapeutic targets for ovarian-related diseases.

Functional Analysis of a Juvenile Hormone Inducible Transcription Factor, Krüppel homolog 1, in the Bean Bug, Riptortus pedestris

Juvenile hormone (JH) has two major functions in insects, i.e., suppression of metamorphosis in the larval or nymphal stage and promotion of reproduction in the adult stage. Krüppel homolog 1 (Kr-h1), a C2H2 zinc-finger type transcription factor, is reported to act downstream of the JH receptor complex. In the present study, the function of Kr-h1 was examined in adults and nymphs of Riptortus pedestris by RNA interference (RNAi). After injection of adults with dsRNA of Kr-h1, the expression level of Kr-h1 was significantly decreased in the abdomen. Kr-h1 dsRNA-injection resulted in a lower proportion of individuals with developed ovaries, but the difference was not statistically significant. The transcript levels of cyanoprotein-α and vitellogenin-1, which are JH-inducible genes encoding yolk proteins, were not affected in the abdomen by Kr-h1 knockdown. Kr-h1 dsRNA-injection was effective for suppression of Kr-h1 expression in nymphs. Some Kr-h1 dsRNA-injected fifth (final) instar nymphs had morphological defects in the wing bud. Moreover, they had several adult morphological features, including ocelli in the head, connexivum in the abdomen, coloring of the dorsal abdomen, and genitals. The nymphs possessing adult features did not emerge as adults during 1 month. These results demonstrated that Kr-h1 is necessary for maintaining nymphal characters in R. pedestris. The function of Kr-h1 in ovarian development remains unclear in R. pedestris.

Reproduction does not impede the stopover departure to ensure a potent migration in Cnaphalocrocis medinalis moths

Despite the importance of reproduction in insects, its relation with multi-stop flight remains poorly understood in migratory species. To clarify whether reproductive maturation commences during the multi-stop flight or after the completion of migration, we conducted physiological and behavioral assays in the rice leaf roller Cnaphalocrocis medinalis with laboratory-simulated conditions and field-captured populations. We found that the ovarian development was significantly promoted by tethered flight treatment for 1-2 nights when compared to the unflown group, while the flight muscle development was not impaired. There was no significant difference in flight duration, flight distance and flight velocity between mated and virgin female moths, indicating that mated moths remained competent for the subsequent flights as did the virgins. Using an integrated field assay, we identified that over 60% of the female moths in the migrating populations captured by high-altitude searchlights in the Immigration period of a season had completed the ovarian development and mating. Sexually mature and mated moths collected in the rice field in the Emigration period were found capable of engaging in migratory take-off, as observed using an indoor monitoring platform. Overall, our findings point out that C. medinalis managed to complete reproductive maturation to a large extent during the multi-stop migratory flight without compromising the migration performance. Such a cost-effective strategy ensures a successful migration for the moths. These findings advance our understanding of the relationship between reproduction and migration, thus shedding light on the development of novel control measures for the outbreak of migratory insect pests.

Smith, 1797), and Their Function in Reproduction of Female

The fall armyworm Spodoptera frugiperda is a highly polyphagous invasive pest. The strong reproductive capacity is an important factor in the rapid colonization and expansion of S. frugiperda. Vitellogenin (Vg) and vitellogenin receptor (VgR) play important roles in insect reproduction. As the precursor of vitellin (Vn), Vg provides essential nutrition for embryonic development, and VgR mediates the uptake of Vg by oocytes. In this context, we cloned and characterized these two genes of S. frugiperda (SfVg and SfVgR) and evaluated their expression profiles in different developmental stages and tissues. The RNA interference experiment was used to investigate their function in vitellogenesis. The ORF values of SfVg and SfVgR were 5250 and 5445 bp, encoding 1749 and 1815 amino acid residues, respectively. The qRT-PCR results revealed that both SfVg and SfVgR were highly expressed in female adults; SfVg was specifically expressed in the fat body, whereas SfVgR was highly expressed in the ovary. In addition, the depletion of either SfVg or SfVgR hindered oocyte maturation and ovarian development, leading to a significant decrease in fecundity. The present study reveals the importance of SfVg and SfVgR in the vitellogenesis of S. frugiperda, laying a theoretical foundation for the development of pollution-free pest control strategies with SfVg and SfVgR as new targets.

Functional Role of AsAP in the Reproduction of Adelphocoris suturalis (Hemiptera: Miridae)

Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) is an omnivorous agricultural pest that has severe economic impacts on a diverse range of agricultural crops. Although the targeted disruption of reproductive development among insects has been proposed as a novel control strategy for pest species, the current understanding of the physiology and molecular mechanisms of A. suturalis reproduction is very limited. In this study, we isolated a putative A. suturalisaspartic protease (AsAP) gene that is highly expressed in the fat body and ovaries of sexually mature females. The double-stranded RNA (dsRNA)-mediated knockdown of AsAP suppressed ovarian development and negatively impacted female fertility, which suggested that it plays an essential role in A. suturalis reproduction. The results of this study could help to expand our understanding of A. suturalis reproductive development and have the potential to facilitate the development of effective strategies for the better control of this pest species.

Knockdown of sphingomyelinase (NlSMase) causes ovarian malformation of brown planthopper, Nilaparvata lugens (Stål)

Sphingomyelinases (SMases) are a group of enzymes that catalyse the hydrolysis of sphingomyelins into ceramides and phosphorylcholine. They have been intensively investigated for their pathophysiological roles in mammals whereas much remains unclear about their counterparts in insects. Herein we report the cloning and functional characterization of four SMase homologue genes, designated NlSMase1-4, from brown planthopper (BPH). The phylogenetic analysis revealed that NlSMase1 and NlSMase2 were clustered into acid SMase family, and NlSMase3 and NlSMase4 with neutral SMase family. NlSMase1, NlSMase3 and NlSMase4 were highly expressed in BPH females, and NlSMaes2 in the 5th instar nymph. All four NlSMases had the lowest transcription in BPH males. NlSMase1 and NlSMase4 were highly expressed in BPH ovaries, while NlSMase2 and NlSMase3 in midgut and wings, respectively. Knocking-down of each NlSMase individual by RNA interference (RNAi) caused the ovarian malformation in BPH. The transcriptomic analysis revealed that NlSMase4 knockdown could strongly affect diacylglycerol (DAG)-related metabolisms and their downstream pathways. Further, qRT-PCR analysis of vitellogenin (Vg) genes indicates that the DAG metabolism disorder could interrupt the essential Vg accumulation for BPH oogenesis. Our study demonstrates the vital role of NlSMases in BPH reproductive development and provides new insights into the mediated mechanism of how SMases function.

Dynamics of ovarian maturation during the annual reproductive cycle of the endangered fish Steindachneridion parahybae (Siluriformes: Pimelodidae) in captivity

To characterize the female reproductive biology of the endangered species Steindachneridion parahybae in captivity, the authors used the concentration of gonadal steroids and the oocyte development during the annual reproductive cycle (RC) and after artificial induced spawning (AIS) until 48 h. Three stages of gonadal maturation were identified, based on morphological and physiological features: early maturation or previtellogenic (PRV) oocyte, advanced maturation or vitellogenic (VTG) oocyte and regression (REG) or follicular atresia. They identified and characterized the following stages of germ cells: oogonia, perinucleolar and cortical alveoli, and VTG and atretic oocytes during RC. The oestradiol levels were higher in PRV than those in VTG and REG during the RC, whereas androgens showed higher levels of oestradiol in VTG than those in PRV and REG. The progestogen levels remained unchanged during the whole RC. The final oocyte maturation (FOM) was achieved after AIS and postovulatory follicles (POF) were identified. Plasma concentration of progestogens (17α,20β-dihydroxy-pregnen-3-one and 17α-hydroxyprogesterone) increased considerably after AIS, remaining high up to 6 h after AIS, and progressively decreased over time after AIS. During RC, the lack of FOM and POFs reveals that captivity negatively impacts S. parahybae reproduction. Nonetheless, the VTG stage of oocytes, reached during RC, is suitable for ovulation induction with artificial hormone manipulation, enabling the reproduction of this species in captivity and being essential for the success of fish farming and/or fish conservation programmes (conservationist aquaculture).

Comparative Transcriptome Analysis Reveals the Process of Ovarian Development and Nutrition Metabolism in Chinese Mitten Crab, Eriocheir Sinensis

Ovarian development is a key physiological process that holds great significance in the reproduction of the Chinese mitten crab (Eriocheir sinensis), which is an economically important crab species for aquaculture. However, there is limited knowledge for the regulatory mechanisms of ovarian development. To study the molecular mechanisms of its ovarian development, transcriptome analysis was performed in the ovary and hepatopancreas of E. sinensis during ovarian stages I (oogonium proliferation), II (endogenous vitellogenesis), and III (exogenous vitellogenesis). The results showed that 5,520 and 226 genes were differentially expressed in the ovary and hepatopancreas, respectively. For KEGG enrichment analysis, the differentially expressed genes in the ovary were significantly clustered in phototransduction-fly, phagosome, and ECM-receptor interaction. Significantly enriched pathways in the hepatopancreas included fatty acid biosynthesis, fatty acid metabolism, and riboflavin metabolism. Further analysis showed that 25 genes and several pathways were mainly involved in oogenesis, including the ubiquitin-proteasome pathway, cyclic AMP-protein kinase A signaling pathway, and mitogen-activated protein kinase signaling pathway. Twenty-five candidate genes involved in vitellogenesis and endocrine regulation were identified, such as vitellogenin, vitellogenin receptor, estrogen sulfotransferase, ecdysone receptor, prostaglandin reductase 1, hematopoietic prostaglandin D synthase and juvenile hormone acid O-methyltransferase. Fifty-six genes related to nutritional metabolism were identified, such as fatty acid synthase, long-chain-fatty-acid-CoA ligase 4, 1-acyl-sn-glycerol-3-phosphate acyltransferase 4, fatty acid-binding protein, and glycerol-3-phosphate acyltransferase 1. These results highlight the genes involved in ovarian development and nutrition deposition, which enhance our understanding of the regulatory pathways and physiological processes of crustacean ovarian development.

Recognition of Gonadal Development in Eriocheir sinensis Based on the Impulse of Love at First Sight

Given the difficulty in identifying individuals with different degrees of ovarian development, we developed a new device utilizing the hypothesis of mutual attraction behavior between male and female crabs with mature gonads by releasing the sexual pheromone so they could be examined. From a total of 40 female crabs, 10 were isolated within half an hour. Histological analysis showed that the ovaries of crabs in the isolated group were in stage IV, while those of the control groups were in stage III. In addition, progesterone (PROG) in experimental groups was significantly reduced compared with the control group (p < 0.05), but no significant difference was detected in estradiol (E2). In response to the different developmental stages, hemolymph biochemical indices and the determination of gonadal fatty acids profiles were explored. The results indicated only C18:4 showed a significant difference between these two groups. A transcriptome was generated to determine the genes involved in the mutual attraction process; differentially expressed genes (DEGs) were significantly related to gonadal development. Therefore, the device can be used to isolate Chinese mitten crabs with stage IV ovarian development.

Expression profiles of cdca9 related to ovarian development in loach (Misgurnus anguillicaudatus)

The function of borealin proteins has been widely reported in the cell division of animals. Nonetheless, there is little research about their only known paralogue (cell division cycle associated 9, cdca9). In this study, cdca9 was investigated in loach (Misgurnus anguillicaudatus) for the first time. cdca9 was highly expressed in the embryo before the gastrula stage, and it was predominantly expressed in the ovary, especially in the oocytes of stage II. In conclusion, this study reveals a potential function of cdca9 in the early embryogenesis and ovarian development of fish.

Effects of stocking density on ovarian development and maturation during the rearing period in Shan-ma ducks

Stocking density critically affects the growth and subsequent performance of animals in modern poultry production. This study investigated the effects of stocking density on ovarian development, ovarian maturation, and the mRNA expression of key genes in the reproductive axis during the rearing period of Shan-ma ducks. The experiments involved 180 healthy 7-wk-old Shan-ma ducks and randomly divided into low stocking density (LSD; n = 30, density = 5 birds/m²), medium stocking density (MSD; n = 60, density = 10 birds/m²) and high stocking density groups (HSD; n = 90, density = 15 birds/m²), for rearing. After examining ovarian development and measuring hormone levels in the plasma and expression levels of key regulatory genes in the reproductive axis at 19 wk of rearing, analysis of the gonad index analysis, reflecting stocking density, uncovered statistically significant differences. The gonad index of the LSD group was significantly higher than those of the MSD and HSD groups (P < 0.01), while no significant difference was observed between the MSD and HSD groups. pre-ovulatory follicles (POFs) and small yellow follicles (SYFs) development was only apparent in the LSD group, with the large white follicles (LWFs) number of this group being significantly higher than that of the MSD group (P < 0.05). The blood levels of E2 (estradiol), P4 (progesterone), and T (testosterone) were significantly higher in the LSD group than in the MSD and HSD groups (P < 0.05 or 0.01). Also, the levels of both P4 and T were significantly higher in the MSD group than in the HSD group (P < 0.01). The gene expression levels of GnRHR, FSH, AMHR, and FSHR were significantly increased in the LSD group compared to the MSD and HSD groups (P < 0.05 or 0.01), while the expression levels of GnIHR and GDF9 were significantly decreased in the LSD and MSD groups compared to the HSD group (P < 0.05 or 0.01). Steroid biosynthesis pathway genes such as StAR, CYP11A1, 3β-HSD, CYP19A1, and BMP15 were significantly downregulated at greater stocking densities (P < 0.05 or 0.01). Likewise, the protein expression of StAR, 3β-HSD, and CYP19A1 was also significantly decreased (P < 0.05 or 0.01). These results demonstrate that both medium and high stocking densities suppressed the expression of the key reproduction-promoting factors, while the expression level of the key reproductive inhibitory factors was enhanced. Therefore, rates of ovarian development and maturation could be reduced by a high stocking density leading to a delay in reproduction performance during the rearing period of Shan-ma ducks.

Flying males mediate oviposition and migration in female Mythimna separata (Lepidoptera: Noctuidae)

In recent decades, the oriental armyworm, Mythimna separata (Walker), has caused severe damage to staple grains in China. However, little is known about when M. separata begin their first migration and the role of males in reproduction and migration. Here, the migratory benefits and reproductive costs of flight frequency were examined in adults under laboratory conditions. We found that flying males had a positive effect on ovarian and reproductive development in females who flew for 1-2 nights by comparing two treatment groups (flying and nonflying male groups). Moreover, flying males decreased the flight capacity and flight propensity of females. In contrast, flight for more than two nights by males significantly inhibited ovarian and reproductive development in adult females. Compared with the controls (0 night), male flight for 1-2 nights significantly shortened the preoviposition period but significantly increased ovarian and reproductive development in females. However, male flight for more than three nights significantly inhibited female reproduction and flight capacity. These results indicate that M. separata begin their first migration within 2 days after emergence and fly for two nights. Prolonged flight times can result in significant reproductive costs. Females initiated their first migration earlier than males due to a stronger flight capacity. These observed findings will be useful for forecasting and monitoring population dynamics to prevent outbreaks of M. separata and reduce crop losses.

Genetics of ovarian insufficiency and defects of folliculogenesis

Primary ovarian insufficiency (POI) is determined by exhaustion of follicles in the ovaries, which leads to infertility before the age of 40 years. It is characterized by a strong familial and heterogeneous genetic background. Therefore, we will mainly discuss the genetic basis of POI in this review. We identified 107 genes related to POI etiology in mammals described by several independent groups. Thirty-four of these genes (AARS2, AIRE, ANTXR1, ATM, BMPR1B, CLPP, CYP17A1, CYP19A1, DCAF17, EIF2B, ERAL1, FANCA, FANCC, FMR1, FOXL2, GALT, GNAS, HARS2, HSD17B4, LARS2, LMNA, MGME1, NBN, PMM2, POLG, PREPL, RCBTB1, RECQL2/3/4, STAR, TWNK, and XRCC4/9) have been linked to syndromic POI and are mainly implicated in metabolism function and meiosis/DNA repair. In addition, the majority of genes associated with nonsyndromic POI, widely expanded by high-throughput techniques over the last decade, have been implicated in ovarian development and meiosis/DNA repair pathways (ATG7, ATG9, ANKRD31, BMP8B, BMP15, BMPR1A, BMPR1B, BMPR2, BNC1, BRCA2, CPEB1, C14ORF39, DAZL, DIAPH2, DMC1, ERCC6, FANCL, FANCM, FIGLA, FSHR, GATA4, GDF9, GJA4, HELQ, HSF2BP, HFM1, INSL3, LHCGR, LHX8, MCM8, MCM9, MEIOB, MSH4, MSH5, NANOS3, NOBOX, NOTCH2, NR5A1, NUP107, PGRMC1, POLR3H, PRDM1, PRDM9, PSMC3IP, SOHLH1, SOHLH2, SPIDR, STAG3, SYCE1, TP63, UBR2, WDR62, and XRCC2), whereas a few are related to metabolic functions (EIF4ENIF1, KHDRBS1, MRPS22, POLR2C). Some genes, such as STRA8, FOXO3A, KIT, KITL, WNT4, and FANCE, have been shown to cause ovarian insufficiency in rodents, but mutations in these genes have yet to be elucidated in women affected by POI. Lastly, some genes have been rarely implicated in its etiology (AMH, AMHR2, ERRC2, ESR1, INHA, LMN4, POF1B, POU5F1, REC8, SMC1B). Considering the heterogeneous genetic and familial background of this disorder, we hope that an overview of literature data would reinforce that genetic screening of those patients is worthwhile and helpful for better genetic counseling and patient management.

The Ovarian Development Genes of Bisexual and Parthenogenetic Haemaphysalis longicornis Evaluated by Transcriptomics and Proteomics

The tick Haemaphysalis longicornis has two reproductive groups: a bisexual group (HLBP) and a parthenogenetic group (HLPP). The comparative molecular regulation of ovarian development in these two groups is unexplored. We conducted transcriptome sequencing and quantitative proteomics on the ovaries of HLBP and HLPP, in different feeding stages, to evaluate the molecular function of genes associated with ovarian development. The ovarian tissues of HLBP and HLPP were divided into three feeding stages (early-fed, partially-fed and engorged). A total of 87,233 genes and 2,833 proteins were annotated in the ovary of H. longicornis in the different feeding stages. The differentially expressed genes (DEGs) of functional pathway analysis indicated that Lysosome, MAPK Signaling Pathway, Phagosome, Regulation of Actin Cytoskeleton, Endocytosis, Apoptosis, Insulin Signaling Pathway, Oxidative Phosphorylation, and Sphingolipid Metabolism were most abundant in the ovary of H. longicornis in the different feeding stages. Comparing the DEGs between HLBP and HLPP revealed that the ABC Transporter, PI3K-Akt Signaling Pathway and cAMP Signaling Pathway were the most enriched and suggested that the functions of signal transduction mechanisms may have changed during ovarian development. The functions of the annotated proteome of ovarian tissues were strongly correlated with the transcriptome annotation results, and these were further validated using quantitative polymerase chain reaction (qPCR). In the HLBP, the expression of cathepsin L, secreted proteins and glycosidase proteins was significantly up-regulated during feeding stages. In the HLPP, the lysozyme, yolk proteins, heat shock protein, glutathione S transferase, myosin and ATP synthase proteins were up-regulated during feeding stages. The significant differences of the gene expression between HLBP and HLPP indicated that variations in the genetic background and molecular function might exist in the two groups. These results provide a foundation for understanding the molecular mechanism and exploring the functions of genes in the ovarian development of different reproductive groups of H. longicornis.

Ovarian Development and Larval Release of the Hermit Crab Clibanarius eurysternus (Hilgendorf, 1879) (Decapoda: Anomura: Diogenidae) in Okinawa, Japan

This study investigated ovarian development and larval release in the hermit crab Clibanarius eurysternus, which inhabits the upper intertidal zone on Okinawa, Japan. Adult females were collected monthly and had a high gonadosomatic index (GSI) from May to October. Oocytes at vitellogenic stages were observed from May to October. Some females had post-ovulatory follicles in the ovary and embryos on the abdomen (ovigerous females) in June and August, suggesting active ovarian development and larval release during these months (breeding season). When adult females were collected weekly according to the lunar cycle, a high GSI with oocytes at the tertiary yolk globule stage in the ovaries was maintained in all lunar phases. Since post-ovulated follicles were seen in ovaries collected around the last quarter and new moons, darkness at night is needed for spawning. Ovigerous females exposed to stepwise changes in hydrostatic pressure exhibited significantly higher synchrony between larval release and high pressure at night from the last quarter moon to the new moon, suggesting the importance of the tidal amplitude cycle in larval release under non-moonlight conditions. We concluded that the continuity of synchronous spawning and larval release of C. eurysternus are repeated under darkness and high tide at night during the breeding season.

Changes in the Hepatic Expression of Three Vitellogenin Subtype Genes During Ovarian Development in Female White-Edged Rockfish (Sebastes taczanowskii)

Viviparous fish, including white-edged rockfish (Sebastes taczanowskii), 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 vtg gene transcripts (vtgAa, vtgAb, vtgC) 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 vtg subtypes increased with the progress of vitellogenesis; both levels decreased at the beginning of oocyte maturation and remained low during the gestation period. Considering the similarity in the transcriptional profiles of vtg subtypes between Sebastes and Oncorhynchus, along with the differences between Sebastes and Morone, it is suggested that the transcription patterns of multiple vtg genes relate to neither their reproductive modes (viviparity versus oviparity) nor to teleost phylogeny.

Knockdown of specific cuticular proteins analogous to peritrophin 3 genes disrupt larval and ovarian development in Bactrocera dorsalis (Diptera: Tephritidae)

Cuticular proteins (CPs) are critical components of the insect cuticle and play important roles in maintaining normal insect development and defense against various environmental stresses. The oriental fruit fly (Bactrocera dorsalis) is one of the most destructive pests worldwide, and its eight CPs analogous to peritrophin 3 (BdCPAP3) family genes have been identified in our previous study. In the present study, we further explored the possible roles of CPAP3 genes in B. dorsalis development. Each sequence of BdCPAP3 genes contained three conserved ChtBD2 (chitin-binding) domains. Spatial and temporal expression patterns revealed that the four BdCPAP3 genes (BdCPAP3-A1, B, E, and E2) might play important roles in larval pupariation of B. dorsalis. Moreover, treatment with a juvenile hormone analog (methoprene) significantly restricted expression of these four CPAP3 genes, whereas treatment with 20-hydroxy-ecdysone induced expression. The RNA interference (RNAi) results revealed that down-regulated CPAP3 genes led to significant delay of pupariation, and injection of dsBdCPAP3-E into 5-d-old B. dorsalis larvae caused approximately 40% mortality. Interestingly, we also confirmed that BdCPAP3-D2 was involved in B. dorsalis ovarian development. This study showed that some specific CPAP3 genes had crucial roles in B. dorsalis development, and these CP genes could be used as potential targets to control this pest via RNAi.

Comparative neuroanatomical distribution and expression levels of neuropeptide F in the central nervous system of the female freshwater prawn, Macrobrachium rosenbergii, during the ovarian cycle

Neuropeptide F (NPF) plays critical roles in controlling the feeding and reproduction of prawns. In the present study, we investigated changes in the expression levels of Macrobrachium rosenbergii neuropeptide F (MrNPF), and its neuroanatomical distribution in eyestalk (ES), brain (BR), subesophageal ganglion (SEG), thoracic ganglia (TG), and abdominal ganglia (AG), during the ovarian cycle of female prawn. By qRT-PCR, the amount of MrNPF transcripts exhibited a gradual increase in the ES, BR, and combined SEG and TG from stages I and II, to reach a maximum level at stage III, and slightly declined at stage IV, respectively. The highest to lowest expression levels were detected in combined SEG and TG, BR, ES, and AG, respectively. MrNPF immunolabeling was observed in several neuronal clusters, associated fibers, and neuropils of these central nervous system (CNS) tissues. MrNPF-ir was more intense in neurons and neuropils of SEG and TG than those found in other parts of the CNS. The number of MrNPF-ir neurons and intensity of MrNPF-ir were higher in the ES, BR, SEG, and TG at the late stages than those at the early stages of the ovarian cycle, while those in AG exhibited insignificant change. Taken together, there is a correlation between changes in the neuroanatomical distribution of MrNPF and stages of the ovarian cycle, implying that MrNPF may be an important neuropeptide that integrates sensory stimuli, including photo-, chemo-, and gustatory receptions, to control feeding and reproduction, particularly ovarian development, of this female prawn, M. rosenbergii.

KIF2A regulates ovarian development via modulating cell cycle progression and vitollogenin levels

The kinesin superfamily of proteins (KIFs) are microtubule motor proteins that use the hydrolysis of ATP to power directional movement along microtubules. KIFs induce microtubule depolymerization to regulate the length and dynamics of microtubules in a variety of cell processes and structures, including the mitotic and meiotic spindles and centriole and interphase microtubules. KIF plays a significant role in the transport of organelles, protein complexes and mRNAs. The brown planthopper (Nilaparvata lugens) is a major insect pest in rice paddy fields. Ovarian development is regulated by multiple factors, including endocrine factors. The role of KIFs in brown planthopper ovarian development remains unknown. We found that downregulation of KIF2A significantly compromised the development and eclosion of the brown planthopper, delayed ovarian cell cycle progression, disrupted ovarian development, reduced the expression of MCM genes required for DNA replication and significantly reduced the number of nuclei in the follicles. We also found a significant reduction in Vg mRNA and protein levels. We conclude that downregulation of KIF2A disrupts the cell cycle progression of cells. Alternatively, the ovarian phenotype could be an indirect effect of a compromised trophic cord. In summary, KIF2A regulates ovarian development via modulating cell cycle progression and/or vitollogenin transportation.

The RNA helicase DDX3 is required for ovarian development and oocyte maturation in Locusta migratoria

DDX3 represents a well-defined subfamily of DEAD-box RNA helicase and exerts multiple functions in RNA metabolism, cell cycle, tumorigenesis, signal pathway, and fertility. Our previous study has shown that LmDDX3, the ortholog of DDX3 in Locusta migratoria, is ubiquitously expressed, and with a high abundance in testis and ovary. Knockdown of LmDDX3 results in a lethal phenotype in nymph, but it still remains unclear for its role in reproductive process. In this study, we therefore characterized LmDDX3 expression in female adult locust and analyzed its function in oocyte development. LmDDX3 was expressed in all tissues examined with significant more transcripts in ovary and hindgut. In ovary, a strong expression level was detected at the day just after adult eclosion, and a dramatic reduction then occurred during the oocyte development. LmDDX3 RNAi led to a reduced vitellogenin (Vg) expression in fat body via partially at least, the JH signaling pathway, and caused an upregulation of vitellogenin receptor (VgR) in ovary, and thus blocked the ovarian development and oocyte maturation. Sequence and phylogenetic analysis indicated that LmDDX3 was closely related to termite DDX3. Taken together, these data reveal a critical role for LmDDX3 in regulating the transcription of Vg and VgR, two major factors in vitellogenesis that is a key process required for ovary development and oocyte maturation in locust, and contribute thereof a new putative target for locust biological control.

Dose-Effect of Zearalenone on the Localization and Expression of Growth Hormone, Growth Hormone Receptor, and Heat Shock Protein 70 in the Ovaries of Post-weaning Gilts

Zearalenone (ZEA) has an estrogen-like effect, which can injure the reproductive system of animals, causing infertility, and abortion in sows. However, the underlying mechanisms are still not clear. The objective of this study was to assess the effects of ZEA on the localization and expression of growth hormone (GH), growth hormone receptor (GHR), and heat shock protein 70 (Hsp70) in the ovaries of post-weaning gilts. Forty healthy post-weaning gilts were randomly provided one of four diets: normal basal diet supplemented with 0 (control), 0.5 (ZEA0.5), 1.0 (ZEA1.0), and 1.5 (ZEA1.5) mg ZEA/kg. Gilts were housed and fed individually for 35 days; the ovaries were collected after euthanasia for antioxidant index, relative mRNA and protein expression, and immunohistochemical analyses of GH, GHR, and Hsp70. The results revealed that the glutathione peroxidase and total superoxide dismutase levels decreased (p < 0.05), whereas the malondialdehyde level increased (p < 0.05) with increasing ZEA content. The localization pattern of GH, GHR, and Hsp70 in ZEA-treated gilts was the same as that in the control; however, the localization of yellow and brown immunoreactive substances of GH, GHR, and Hsp70 was stronger in the ZEA groups than in the control. The relative mRNA and protein expression of GHR and Hsp70 was the highest in the ZEA1.0 group (p < 0.05), whereas that of GH was the highest in the ZEA0.5 group (p < 0.05). The mRNA and protein expression of GH was lower in the ZEA1.5 group than in the control (p < 0.05). Hsp70 results showed adverse responses to increasing ZEA levels in gilt ovaries, suggesting that Hsp70 played an important role in alleviating ZEA-induced oxidative stress.

Pollen Source Affects Development and Behavioral Preferences in Honey Bees

Simple Summary

Pollinators adjust their foraging preference based on the pollen cues of foraging plants. Honey bees, for example, prefer to collect one type of pollen from plants that bloom at the same time. In northern China, apricot and pear trees are the two main foraging plants in the early spring. However, honey bees tend to collect pollen from apricot trees. It is interesting to understand what affects the foraging decision of honey bees regarding these two pollen types. In this study, we observed the foraging preference of Apis mellifera workers with respect to apricot and pear pollen under laboratory conditions. The effect of pollen on the development of the hypopharyngeal gland (HG) and ovary was measured. The number of visits made to apricot pollen was significantly higher than that to pear pollen. Furthermore, the response of the HG and ovary to these two pollens was different. The development of the HG was significantly affected by pollen diet treatments. However, there was no significant difference in the ovarian development of caged workers supplied with the two different pollen diets. Overall, honey bees showed a significant preference for apricot pollen over pear pollen. Compared with the ovary, the HG of honey bee workers may be more sensitive to pollen nutrition.

Abstract

With the availability of various plants in bloom simultaneously, honey bees prefer to collect some pollen types over others. To better understand pollen’s role as a reward for workers, we compared the digestibility and nutritional value of two pollen diets, namely, pear (Pyrus bretschneideri Rehd.) and apricot (Armeniaca sibirica L.). We investigated the visits, pollen consumption, and pollen extraction efficiency of caged Apis mellifera workers. Newly emerged workers were reared, and the effects of two pollen diets on their physiological status (the development of hypopharyngeal glands and ovaries) were compared. The choice-test experiments indicated a significant preference of A. mellifera workers for apricot pollen diets over pear pollen diets (number of bees landing, 29.5 ± 8.11 and 9.25 ± 5.10, p < 0.001 and pollen consumption, 0.052 ± 0.026 g/day and 0.033 ± 0.013 g/day, p < 0.05). Both pollen diets had comparable extraction efficiencies (67.63% for pear pollen and 67.73% for apricot pollen). Caged workers fed different pollen diets also exhibited similar ovarian development (p > 0.05). However, workers fed apricot pollen had significantly larger hypopharyngeal glands than those fed pear pollen (p < 0.001). Our results indicated that the benefits conferred to honey bees by different pollen diets may influence their foraging preference.

Tomato Chlorosis Virus Infection Facilitates Bemisia tabaci MED Reproduction by Elevating Vitellogenin Expression

Simple Summary

The sweet potato whitefly, Bemisia tabaci, is a polyphagous, global invasive insect pest. It can damage vegetables and crops directly by feeding and indirectly by transmitting plant viruses. Previously, we showed that virus infection of host plants can promote B. tabaci MED (Q biotype) reproduction. Here, using a whitefly-tomato chlorosis virus (ToCV)-tomato system, we investigated how ToCV modulates B. tabaci reproduction to facilitate its spread. ToCV infection significantly increased whitefly fecundity and the relative expression of vitellogenin gene (Vg). Both ovarian development and fecundity of whitefly were suppressed when Vg expression was silenced with or without ToCV infection. These combined results reveal that ToCV infection increases B. tabaci MED fecundity via elevated vitellogenin gene expression.

Abstract

Transmission of plant pathogenic viruses mostly relies on insect vectors. Plant virus could enhance its transmission by modulating the vector. Previously, we showed that feeding on virus infected plants can promote the reproduction of the sweet potato whitefly, Bemisia tabaci MED (Q biotype). In this study, using a whitefly-Tomato chlorosis virus (ToCV)-tomato system, we investigated how ToCV modulates B. tabaci MED reproduction to facilitate its spread. Here, we hypothesized that ToCV-infected tomato plants would increase B. tabaci MED fecundity via elevated vitellogenin (Vg) gene expression. As a result, fecundity and the relative expression of B. tabaci MED Vg was measured on ToCV-infected and uninfected tomato plants on days 4, 8, 12, 16, 20 and 24. The role of Vg on B. tabaci MED reproduction was examined in the presence and absence of ToCV using dietary RNAi. ToCV infection significantly increased B. tabaci MED fecundity on days 12, 16 and 20, and elevated Vg expression on days 8, 12 and 16. Both ovarian development and fecundity of B. tabaci MED were suppressed when Vg was silenced with or without ToCV infection. These combined results suggest that ToCV infection increases B. tabaci MED fecundity via elevated Vg expression.

Vitellogenin Receptor (VgR) Mediates Oocyte Maturation and Ovarian Development in the Pacific White Shrimp (Litopenaeus vannamei)

Oocyte maturation and ovarian development are sequentially coordinated events critical to reproduction. In the ovaries of adult oviparous animals such as birds, bony fish, insects, and crustaceans, vitellogenin receptor (VgR) is a plasma membrane receptor that specifically mediates vitellogenin (Vg) transport into oocytes. Accumulation of Vg drives sexual maturation of the female crustaceans by acting as a pivotal regulator of nutritional accumulation within oocytes, a process known as vitellogenesis. However, the mechanisms by which VgR mediates vitellogenesis are still not fully understood. In this study, we first identified a unique VgR (Lv-VgR) and characterized its genomic organization and protein structural domains in Litopenaeus vannamei, a predominant cultured shrimp species worldwide. This newly identified Lv-VgR phylogenetically forms a group with VgRs from other crustacean species within the arthropod cluster. Duplicated LBD/EGFD regions are found exclusively among arthropod VgRs but not in paralogs from vertebrates and nematodes. In terms of expression patterns, Lv-VgR transcripts are specifically expressed in ovaries of female shrimps, which increases progressively during ovarian development, and rapidly declines toward embryonic development. The cellular and subcellular locations were For analyzed by in situ hybridization and immunofluorescence, respectively. The Lv-VgR mRNA was found to be expressed in the oocytes of ovaries, and Lv-VgR protein was found to localize in the cell membrane of maturing oocytes while accumulation of the ligand Vg protein assumed an even cytoplasmic distribution. Silencing of VgR transcript expression by RNAi was effective for stunting ovarian development. This present study has thus provided new insights into the regulatory roles of VgR in crustacean ovarian development.

Integrative Proteomic and MicroRNA Analysis: Insights Into Mechanisms of Eyestalk Ablation-Induced Ovarian Maturation in the Swimming Crab Portunus trituberculatus

Eyestalk ablation is the most common method to induce ovarian maturation in decapod crustacean aquaculture, but it jeopardizes broodstock survival and larvae production. It is important to understand the molecular basis underlying the maturation triggered by ablation and thereby develop an alternative measure for maturation manipulation. In this study, we investigate alterations of ovarian proteome and miRNA profile after ablation in a commercially important marine crab Portunus trituberculatus. Quantitative proteomic analysis using iTRAQ reveals that 163 proteins are differentially expressed following ablation, and modulation of methyl farnesoate metabolism and activation of calcium signaling may play important roles in the ovarian maturation induced by ablation. miRNA expression profiling identifies 31 miRNAs that show statistically significant changes. Integration of miRNA and proteome expression data with miRNA target prediction algorithms generates a potential regulatory network consisting of 26 miRNAs and 30 proteins linked by 71 possible functional associations. The miRNA-protein network analysis suggests that miRNAs are involved in promoting ovarian maturation by controlling expression of proteins related to methyl farnesoate synthesis, calcium signals, and energy metabolism. Experimental validation and temporal expression analysis indicate multiple miRNAs can act synergistically to regulate expression of Farnesoic acid O-methyltransferase and Calmodulin. Our findings provide new insights for elucidating the mechanisms underlying eyestalk ablation-induced ovarian maturation and could be useful for devising an alternative technique for manipulating reproduction in P. trituberculatus and other decapods.

Bone Morphogenetic Protein 15 Knockdown Inhibits Porcine Ovarian Follicular Development and Ovulation

Bone morphogenetic protein 15 (BMP15) is strongly associated with animal reproduction and woman reproductive disease. As a multifunctional oocyte-specific secret factor, BMP15 controls female fertility and follicular development in both species-specific and dosage-sensitive manners. Previous studies found that BMP15 played a critical role in follicular development and ovulation rate in mono-ovulatory mammalian species, especially in sheep and human, but study on knockout mouse model implied that BMP15 possibly has minimal impact on female fertility of poly-ovulatory species. However, this needs to be validated in other poly-ovulatory species. To investigate the regulatory role of BMP15 on porcine female fertility, we generated a BMP15-knockdown pig model through somatic nuclear transfer technology. The BMP15-knockdown gilts showed markedly reduced fertility accompanied by phenotype of dysplastic ovaries containing significantly declined number of follicles, increased number of abnormal follicles, and abnormally enlarged antral follicles resulting in disordered ovulation, which is remarkably different from the unchanged fertility observed in BMP15 knockout mice. Molecular and transcriptome analysis revealed that the knockdown of BMP15 significantly affected both granulosa cells (GCs) and oocytes development, including suppression of cell proliferation, differentiation, and follicle stimulating hormone receptor (Fshr) expression, leading to premature luteinization and reduced estradiol (E2) production in GCs, and simultaneously decreased quality and meiotic maturation of oocyte. Our results provide in vivo evidence of the essential role of BMP15 in porcine ovarian and follicular development, and new insight into the complicated regulatory function of BMP15 in female fertility of poly-ovulatory species.

Changes in Plasma and Ovarian Steroid Hormone Level in Wild Female Blue Tang Fish Paracanthurus hepatus during a Reproductive Cycle

Simple Summary

Live blue tang fish from Khanh Hoa to Binh Thuan seawaters (a central marine region of Vietnam) were collected monthly for the duration of 12 months and the levels of testosterone (T), estradiol-17β (E₂) and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) in the plasma and the gonad; gonadosomatic index were determined. The gonadosomatic index (GSI%) maintained high values from April to July and increased from the II to IV ovarian stages and dropped in the V stage. Levels of plasma and ovary T and E₂ and DHP were high from March to July. Plasma T and E₂ levels were low in the II stage when most oocytes were previtellogenic, reaching a peak during spawning and decreased in the V stage when fish were going to late spawning and termination.

Abstract

This study aimed to document the seasonal cycle of steroid levels in the plasma and ovary, including testosterone (T), estradiol-17β (E₂) and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) in relation to ovarian development in wild populations of female blue tang fish. The gonadosomatic index (GSI%) maintained high values from April to July and increased from the II to IV ovarian stages and dropped in the V stage. Levels of plasma, ovary T and E₂ and DHP were high from March to July. Plasma T and E₂ levels were low in the II stage when most oocytes were previtellogenic, reaching a peak during spawning, and decreased in the V stages when fish were going to late spawning and termination. DHP was detected in all stages of the ovary with a higher level in spawning fish but decreased after spawning. These results revealed that T, E₂ and DHP could be involved in ovarian development and DHP may play a significant role as a maturational inducing hormone in blue tang fish.

Dynamic Expression and Regulation of Urotensin I and Corticotropin-Releasing Hormone Receptors in Ovary of Olive Flounder Paralichthys olivaceus

Urotensin I (UI), a fish corticotropin-releasing hormone (CRH) like peptide, has been found throughout vertebrate species that has great effects on adaptive physiology comprising stress-related responses, and osmotic regulation by binding with CRH type I receptor (CRHR1) and CRH type II receptor (CRHR2) in fish. Dynamic expression and regulation of UI and CRH receptors in the olive flounder ovarian follicle were studied so as to make further efforts to understand the role of UI in the development of teleost ovary. The results showed that stage-specific change in UI mRNA levels in ovarian follicles of olive flounder. UI and CRHR1 mRNA levels were higher in stage III follicles (300∼500 μm diameter) compared to stage II (90∼300 μm diameter) and IV (500∼800 μm diameter) follicles, however, the levels of CRHR2 mRNA were decreased in line with the ovarian development from stage II to stage IV. A strong signal of UI protein was observed in the follicular cells and oocyte in stage III and IV follicles by immunohistochemistry. In vitro treatment of olive flounder ovarian follicles with human chorionic gonadotropin (hCG) showed that the mRNA expression of UI increased significantly at low concentration and decreased at high concentration at 6 h, but the CRHR1 and CRHR2 mRNA did not change obviously. In addition, the results of incubation with 17α, 20β-dihydroxy-4-oregnen-3-one (DHP) show that UI and CRHR1 mRNA expression were elevated with increasing concentrations at 9 h. All above results indicated that UI and CRH receptors may have a vital effect on olive flounder ovarian development.