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MiR-202-5p is identified as the maker microRNA (miRNA) of germplasm in fish. However, the role of miR-202-5p in gonadal development is still unclear. Here we investigated the expression patterns of miR-202-5p in Japanese flounder (Paralichthys olivaceus). Real-time PCR displayed that miR-202-5p was specifically expressed in bisexual gonads, and its transcription in the testis was relatively abundant than that in the ovary. Moreover, it was gradually increased in testis from stage II to stage IV. Fluorescent in situ hybridization (FISH) illustrated that miR-202-5p was co-localized with vasa (a marker gene of germ cells) in testis, and it was predominately expressed in spermatogonia and spermatocytes, implying that miR-202-5p might participate in spermatogenesis. Considering the important role of retinoic acid (RA) on regulating meiosis during spermatogenesis, we treated Japanese flounders by injecting all-trans retinoic acid (ATRA). MiR-202-5p in testis was shown to be up-regulated, and ccnd1, a key cell cycle regulator, was found to be down-regulated after ATRA treatment. Furthermore, ccnd1 was demonstrated to be a direct regulatory target of miR-202-5p using Dual-luciferase assay. In the primary testis cell from Japanese flounder, we further confirmed that ccnd1 was down-regulated by miR-202-5p. The results suggest that miR-202-5p exerts a crucial role in gonadal development by inhibiting ccnd1 in Japanese flounder.

The Trachinotus ovatus is a popular aquaculture species in China. There are no obvious morphological differences between male and female fish, even during maturity, prompting research studies on sex-related features of this fish. To examine sex determination- and gonadal development-related genes, we conducted transcriptome analysis of the ovaries and testes of T. ovatus. A total of 345,972,132 high-quality clean reads were obtained from 12 libraries. In addition, 28,137 gonad-expressed unigenes were obtained by mapping the clean reads to the T. ovatus reference genome. A total of 8,237 differentially expressed genes (DEGs) were identified between stage I ovaries and testes, including 3,235 testicular upregulated and 5,002 ovarian upregulated genes. Furthermore, 13,448 DEGs were obtained between stage III ovarian and testicular libraries, including 7,576 testicular upregulated and 5,872 ovarian upregulated genes. The DEGs included some sex-determining genes such as sry, dmrt1, and amh. DEGs between ovarian and testicular libraries were significantly enriched with KEGG pathways that are involved in gonadal development, sex determination, and gonadal function. Then, 10 DEGs (seven testicular upregulated and three ovarian upregulated unigenes) were selected for quantitative real-time PCR analysis. Four genes (zinc-binding protein A33-like, pro-opiomelanocortin-like, leucine-rich repeat and transmembrane domain-containing protein 2-like, and forkhead boxC1) showed a specific testicular expression pattern. The gonadally expressed as well as testicular and ovarian DEGs provide useful information for further research on the reproductive biology of T. ovatus.

The blue swimmer crab (BSC, Portunus armatus) is an economically and culturally important species distributed throughout the coastal waters of the Indo-Pacific region. Reproduction of BSC is poorly understood in south-eastern Australia, a region that is experiencing substantial tropicalisation from global warming. We examined gonadal development, egg–mass relationships, and the influence of temperature on gonadal development and egg production within five different estuaries spanning ~2.5° of latitude. A negative correlation between the gonadosomatic index (GSI, an index of gonadal development and reproductive investment) and hepatosomatic index (HSI, an index of energy storage) was observed in only the final stages of ovarian development. The weight of the egg mass increased logarithmically with body mass, accounting for up to 55% of total body mass, which was significantly larger than observed in other studies. Thermal performance curves showed a peak in individual reproductive output at a mean monthly temperature of ~24°C, at which the individual egg mass weight reached a maximum and the HSI reached a minimum. Environmentally driven variation in BSC reproduction has implications for population productivity and inter-annual variation in recruitment.

In mammals, Yin Yang 1 (YY1), a pervasively expressed transcription factor related to many biological processes as an activator or inhibitor of the transcription of various genes, plays a critical role in the development of male gonads and spermatogenesis. Although the role of YY1 on the development of male gonads and spermatogenesis in mammals has been reported, its function on chicken testis are yet to be clarified. In this study, we used immunofluorescence analysis to investigate the location of YY1 in chicken testis. In embryo testis, YY1 was detected in spermatogonia and Sertoli cells, while in adult testis, YY1 was shown to be expressed in spermatogenic cells and Sertoli cells, but not in spermatozoa. Furthermore, we investigated the regulatory functions of YY1 in chicken testicular Sertoli cells by combining overexpression with RNA-sequencing. Overexpression of YY1 in Sertoli cells revealed a total of 2955 differentially expressed genes involved in various biological processes, such as male gonad development and seminiferous tubule development. Overexpression of YY1 also caused significant differences in the expression of the androgen receptor gene and the inhibin βA gene, two major genes involved in the regulation of spermatogonia in Sertoli cells. These observations indicate that YY1 may regulate the development and function of the gonads by affecting the secretion of cytokines and hormones in Sertoli cells to mediate the production and differentiation of spermatogonia.

The doublesex and mab-3 related transcription factor (DMRT) gene family is conserved from invertebrates to humans. The functions of DMRT are mainly involved in sex development and the formation of many tissues and organs. In this study, a DM (Doublesex/Mab-3)-domain gene was identified in the mud crab Scylla paramamosain, and was named SpDMRT99B because of its many similarities to arthropod DMRT99B and phylogenetically close relationship with arthropod DMRT99B. The cDNA of SpDMRT99B gene is 1249 bp in length, encoding 224 amino acids. From 254 bp to 928 bp there is a conserved DM domain. No transmembrane domain was identified. Through multiple amino acid alignment and phylogenetic tree analysis, the closest gene to SpDMRT99B is Eriocheir sinensis DMRT99B, followed by Macrobrachium rosenbergii and Drosophila melanogaster DMRT99B. The expressions of the gene were characterized in different tissues of female and male crabs during early development period of crab individuals, as well as in different development periods of gonads. The results showed that SpDMRT99B gene is significantly highly expressed in testis than in ovary and other tissues. The expression level of SpDMRT99B in testis at different stages is significantly higher than that in ovary, and it is particularly highly expressed in immature testis. In early developmental stages of larvae, the expressions of SpDMRT99B remain at a low level and reach a peak at zoea stage I when the body segments shape up. It is speculated that SpDMRT99B gene might be involved in the gonadal development process and somitogenesis of S. paramamosain.

Without known analogous sex-determining factors like SRY (sex determining region Y) in mammals, the chicken (Gallus gallus) sex determination mechanism still remains unclear, which highly restricts the biological research on chicken development and poultry single-sex reproduction. Here we not only characterized a new female-biased gene UBE2I and identified the expression pattern by qRT-PCR, but also described the functional role of UBE2I in the gonadal development of chicken embryos. Results showed that UBE2I exhibited a female-biased expression pattern in the early stage of PGCs (primordial germ cells) in embryonic gonads and robust expression in ovaries of newborn chickens. Most importantly, we successfully developed an effective method to interfere or overexpress UBE2I in chicken embryos through the intravascular injection. The qRT-PCR analysis showed that the sex-related genes (FOXL2, CYP19A1 and HINTW) in females were upregulated (P

The establishment and survival of the population of species in their breeding ground can be attributed to the species’ reproductive characteristic and capacity. The Monopterus albus species is an introduced fish in the Philippines. It is a protogynous hermaphrodite which has a natural ability for sex reversal. This study describes the histomorphology of the different stages of gonadal maturation and determines the concentration levels of the steroid hormones 17ß-estradiol (E2) and testosterone (T) in the blood plasma. These aim to a further understanding on the gonadal development and sex differentiation of the rice paddy eel as a hermaphroditic fish. Fish samples were collected randomly from farm ponds located in three provinces within the island of Luzon, Philippines. The sexual identity of the fish was categorized based on the presence or absence of ovarian and testicular tissues. Histological analysis of the gonad showed that immature, maturing-matured female gonad exhibited ovarian tissues of varying stages. The intersex gonad showed the existence of both ovarian and testicular tissues. Enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration levels of gonadal steroid hormones. Differences in the concentration levels of the two hormones were evident across all the stages of gonad maturation. The functional role of these hormones in vitellogenesis and spermatogenesis leads to the development of this sex-changing gonads. This reproductive characteristic contributes to our understanding of the reproductive success of hermaphroditic fish.

A 100-day growth trial was conducted to evaluate the effects of dietary protein mixtures (PM) adding proportion on both sexes of the red swamp crayfish, Procambarus clarkii (Girard, 1852). Five diets were prepared by replacing 0%, 16.67%, 33.33%, 50%, and 66.67% of fish meal (FM) protein with protein mixtures in feed (designed Diet 1, Diet 2, Diet 3, Diet 4 and Diet 5). The results showed that growth performance presented a decreasing trend with an increase in dietary protein mixture levels. The GSI of female crayfish and the HSI of male crayfish initially increased and then decreased with increasing dietary protein mixtures. Interestingly, the GSI of males fed Diet 5 was higher than that in other groups (). Diet 2 was the best feed for female gonad development and male muscle quality. Females fed Diet 3 had the highest muscle quality among the groups; males had improved gonad development when fed Diet 5.

Pacific bluefin tuna (PBT), Thunnus orientalis, is one of the most important species for aquaculture in Japan. Recently, the reduction in muscle fat content associated with sexual maturation in farmed PBT has become a serious problem. To develop technologies for inducing sterility, detailed and reliable data on gonadal development in PBT are needed. Here, we demonstrated the process of gonadal sex differentiation, and of early ovarian and testicular development during the immature stages in PBT. Gonadal sex differentiation was first characterized by the formation of the ovarian cavity in female and of the efferent ducts in male 57 days post hatching (dph). The gonads then differentiated into ovaries or testes according to the genotypic sex until 83 dph. During this period, primordial germ cells, oogonia, and type-A spermatogonia were solitarily distributed in the gonads, and the number of germ cells did not differ between sexes. After gonadal sex differentiation, gonads of PBTs developed in a sexually dimorphic manner: proliferation and differentiation of germ cells occurred earlier in the ovaries than in the testes. The oogonia in ovaries formed cysts at 185 dph, but the type-A spermatogonia were solitarily distributed in testes at this stage, and cysts of type-A spermatogonia were first observed at 247 dph. Moreover, the oogonia entered meiosis and differentiated into chromatin-nucleolus stage oocytes until 247 dph, and subsequently into peri-nucleolus stage oocytes until 285 dph, whereas the type-A spermatogonia differentiated into type-B spermatogonia, spermatocytes, spermatids, and spermatozoa from 446 dph onwards. We believe the results of this study provide the necessary basis for future studies on sterile PBT production.

This study aimed to evaluate the effect of the combination of estradiol-17β hormone and spirulina in feed on blood plasma biochemistry, histology, and gonad development of female bada fish (Rasbora argyrotaenia). The research method were an experimental study using a completely randomized design with four treatment combinations and four replications, namely without the addition of the estradiol-17β hormone and spirulina (P0), the addition of the estradiol-17β hormone at 7 g kg-1 feed (P1), the addition of spirulina at 30 g kg-1 feed (P2) and the addition of the estradiol-17β hormone at 7 g kg-1 feed and spirulina at 30 g kg-1 feed. Female bada fish (4.22±1.28 g) were kept in an aquarium measuring 100x50x50 cm3 with a density of seven individuals per aquarium. Fish were fed the treatment twice daily, with 3% of the biomass for six weeks. The test parameters were estradiol-17β hormone concentration, egg diameter, blood plasma glucose concentration, blood plasma total cholesterol concentration, and gonadal histology observations. The experimental results showed that the concentration of the estradiol-17β hormone in the body plasma of treatments P1 and P3 was statistically significantly different (P0.05) on blood plasma biochemistry and egg diameter of bada fish broodstock. A combination of estradiol-17β hormone and spirulina hormones in the feed resulted in better P1 and P3 treatments with higher plasma concentrations of the estradiol-17β hormone. Observations of gonadal development from histology showed that the bada fish gonads belonged to the asynchronous type.

The objective of this experiment was to study the effect of replacing fishmeal as a protein source in tilapia diets with different percentages of soybean meal on gonadal development and fish fertility. Four diets were tested in which fishmeal was partially replaced by four different soybean meal levels (20, 30, 40 and 50%) in tilapia diets. A histological examination was performed to monitor the development of the gonads. Results showed that the final body weight was significantly affected (P< 0.05) by partial replacement of the fishmeal up to 50%. Histological examination of the gonads showed deterioration in the development of the gonads increased by increasing the dietary percentage of soybean meal. Lower replacement rates (20 to 30%) were less effective unless used for a long time, especially in males. When the replacement ratio was 40-50%, the testicular deterioration was clearly observed by the degeneration of the germinal epithelial tissue and the somatic cells that regulating the testis function. Female gonad was also affected by both low and high replacement rates, which resulted in delayed sexual maturity and increased number of degraded eggs. These negative effects can be attributed to contain soybean meal high levels of plant estrogen. As a conclusion, substituting soybean meal instead of fishmeal as a source of protein up to 50% was significantly affect growth performance of tilapia fish. Moreover, increasing the replacement ratio to 40-50%, significantly hampered the development of gonads and fertility of both sexes of tilapia due to the containment of soybean meal high levels of phytoestrogen. Therefore, it could be recommended to avoid using high levels plant protein in broadstock diets to maintain the fish fertility and fecundity.

Pearlscale angelfish Centropyge vrolikii is a kind of protogynous hermaphrodite fish with a natural sexual reversion. Under appropriate social conditions, a female fish can transform into a male fish spontaneously. It is an important prerequisite for artificial breeding to understand the process of its gonadal development and sexual reversion. Gonadal development is regulated by many sex-related genes. In this study, we used unreferenced RNA-Seq technology to sequence the ovary at the perinucleolus stage (OII), ovary at the yolk vesicle stage (OIV),IV and testis (T), respectively; screened the gonadal differential expression genes (DEGs); and analyzed the expression of these genes in different developmental stages of ovary and different sex gonads. The results showed that a total of 142,589 all-unigene samples were assembled, and gene annotation was performed by COG, GO, KEGG, KOG, Pfam, Swissprot, eggNOG, and NR functional database. Comparative analysis revealed that there were 1919 genes that were up-regulated and 1289 genes were down-regulated in comparison to OIV vs OII, while there were 3653 genes that were up-regulated and 2874 genes were down-regulated in comparison of OIV vs T, there were 3345 genes that were up-regulated and 2995 genes were down-regulated in comparison of the OII vs the T. At the same time, the results verified by RT-qPCR were consistent with the variation trend of transcriptome data. Among the results, amh, sox9b, dmrt1, dmrt2, cyp11a, cyp17a, and cyp19a were significantly expressed in the testes, while sox3, sox4, sox11, sox17, and hsd3b7 were significantly expressed in the ovaries. And, the expression of the amh, sox9b, dmrt2, and dmrt1 were low in the OII and OIV, while significantly increased during the ovotestis in the hermaphroditic period (OT), and finally reached the highest level in pure testis after sex reversal. The expression of sox3, sox4, hsd3b7, sox11, and sox17 was significantly reduced during the hermaphroditic period (OT). These results suggested that these genes may play an important role in the process of sex reversal. This study is helpful to further understand the molecular regulation mechanism of gonadal development and sexual reversion in Pearlscale angelfish and also provide important clues for future studies.

Many teleost fishes can withstand long feed deprivation periods, either due to an eventual lack of food or because of their behavior during reproduction and/or parental care. In this work, the effects of total food restriction on the oogenesis, spermatogenesis, and reproductive hormones of the neotropical cichlid fish Cichlasoma dimerus were studied. Specifically, different pairs were isolated after having a spawning event and were feed-deprived or daily fed for 3 weeks. After that period, gonadal histology, messenger levels of genes related to reproduction (gonadotropin-releasing hormone 1, gonadotropins, and insulin-like growth factor 1) and 11-ketotestosterone plasma levels were evaluated in both groups. Food restriction did not affect the reproductive axis in females since follicular maturation and gene expression showed no differences with respect to controls. However, in males, food restriction showed a stimulatory effect on the reproductive axis, reflected in a greater number of spermatozoa in their seminiferous lobes and spermatic ducts, and in an increase in follicle stimulating hormone messenger expression. Despite the negative effect reported for many fish species, C. dimerus seems to redirect their energy reserves towards gonadal development when faced with to a feed deprivation period.

The present research was conducted to investigate the effects of fish oil (FO) substitutions with corn oil (CO) on the gonad development of female Tor tambroides broodstocks, a high value freshwater fish. Three isonitrogenous (450 g kg−1 crude protein) and isolipidic (105 g kg−1 crude lipid) were formulated to contain FO and CO at a ratio of 1:0, 1:1 and 0:1, respectively, and fed to female fish (n = 10 fish × 3 replicate × 3 treatment; average weight = 910.0 ± 130.0 g) for five months. At the end of the feeding trial, there were no significant differences (p > .05) on the gonadosomatic index (GSI), hepatosomatic index, 17β-oestradiol (E2) concentration and muscle fatty acids (FA) composition. However, fish fed with diet containing FO to CO at a ratio of 1:1 demonstrated higher percentage of GSI, E2 concentration (ng ml−1) and the presence of vitellogenic oocytes in the histological data compared to the other two feeding diets. The FA composition also highlighted that T. tambroides broodstocks can elongate polyunsaturated FA to highly unsaturated FA. Based on these preliminary results, it shows that T. tambroides prefer diets with supplementation of both n3 and n6 oil source. However, more studies need to be done to strengthen this conclusion.

The relationship between water temperature and gonadal maturation of a landlocked ecophenotype of marine pejerrey (Odontesthes argentinensis) in La Salada de Pedro Luro lake was analysed during thr...

The present study was conducted to evaluate the effects of dissolved oxygen concentrations on growth, survival and gonadal development of freshwater pearl mussel (Lamellidens marginalis). Twenty adult L. marginalis were exposed to each of the five different concentrations of dissolved oxygen (DO) i.e (T0, no aeration), and T1, T2, T3 and T4 with one, two, three and four air stone aerators, respectively in fifteen glass aquaria each containing 10L of pond water. DO concentrations were significantly higher in all the treatments compared to the control but there were no significant differences among the treatments. There were significant differences in the growth and survival rates between control and treatments. The relative growth rates (%) were significantly higher in the highest oxygen concentration (T4) compared to other treatments. The survival rate was zero in control (T0), whereas it was 66.67%, 70.00%, 71.67% and 73.33%, respectively for T1, T2, T3 and T4. On day-30, oocytes in T0 were found to be smaller in size, with developing acini and no previtellogenic oocytes; whereas in T1, T2, T3 and T4, previtellogenic oocytes and larger acini were evident. On day-60, vitellogenic oocytes along with few under-developed oocytes started to detach from the acini walls, as well as some already started migration to germinal duct on day-90. This indicates that ovaries of all the treatments were ripe and were ready to spawn between day-60 and -90. On day-30, secondary spermatocytes were observed in testicular acini in case of T0, whereas more developed and dense spermatids were evident in T1, T2, T3 and T4. These results indicate that testes were in late development stages in T0, whereas they were ripe in all the treatments. The current findings indicate that hypoxia slows down growth, reduces survival rate and retards development of reproductive organs in L. marginalis.

Maturation of salmonid species reduces growth, flesh quality and immunocompetency and has inhibited, in part, the commercial production of brook trout in Tasmania. Photoperiod manipulation is routinely used to inhibit or reduce the incidence of maturation in salmonids, so an experimental adaptation of this approach was trialled experimentally for brook trout. Mixed-sex fish (age = 14 months) were subjected to simulated natural photoperiod (NP), advanced photoperiod (AP) and continuous photoperiod (CP) to investigate the response of endogenous circannual rhythm upon sexual maturity in this species. Light treatments commenced on the first day of the last month of the southern hemisphere’s winter and concluded towards the end of autumn when fish were ovulating. Maturation was observed in 100% of females and 96% of males held under NP. Fish exposed to AP corrected their maturation cycle by advanced phase shift of their endogenous rhythm for eight weeks and achieved final maturation during March–April. Plasma profiles of testosterone and oestradiol-17β were also adjusted according to advancement of photoperiod. Exposure to AP inhibited maturation by 6% and 8% in males and females, respectively. CP treatment for 10 consecutive months failed to inhibit gonadal development; however, this regime did delay or inhibit spermiation and ovulation.

Ghrelin is a multifunctional peptide hormone which dominantly secreted in stomach and intestine. Ghrelin involves in growth control, food intake, energy balance, and reproductive process. Recent evidences suggested that ghrelin also interacts with hypothalamic–pituitary–gonadal axis (HPG axis) and controls gametes maturation. In addition, current clues showed that via regulating ghrelin system (acyl ghrelin: des acyl ghrelin ratio, GOAT, GHS-R1a), glucose and weight could be regulated promising a potential way for artificial controlling of gonadal development and gamete maturation. The ghrelin signaling system may be a new target for reproductive operation in fish artificial propagation and breeding. This review summarizes the recent studies of the function of ghrelin in fish reproduction and the regulatory methods for ghrelin system.

Menticirrhus americanus were sampled (n = 393) from two beaches (P1 is an estuarine beach near the mouth of the Paranaguá Estuarine Complex, and P2 is a beach adjacent to the Paranaguá Estuarine Complex) in the subtropical region of the western South Atlantic waters between August 2015 and June 2016. This study aimed to identify the spawning season and the age structure for M. americanus using two sampling methods. For sampling at the P1 beach, seine, line, and pole were used, while samples from the P2 beach were obtained from the artisanal fishers. Females were numerically dominant in all sampling months at both sites except for February when the males became dominant. The species exhibited a protected reproductive season with multiple spawning peaks between August and December. Males and females were captured at all gonadal development stages and ages between 1 and 6 from both sites. At first maturity, the length of the females was 16.3 cm, and the mean age at first maturity was 1.3 years. Individuals aged between 1 and 3 years were dominant (68%). The results suggested that young and adults of the M. americanus use the same habitats throughout their ontogeny.

Kisspeptin system is involved in the control of reproduction in vertebrates, including teleost fish. Neuroanatomical distribution of kisspeptin neurons has confirmed their distribution in the preoptic area and hypothalamus of several teleost fish. In few species including chub mackerel, kisspeptin system has been shown to stimulate GnRH neurons in regulating the reproductive processes. Expression changes of kiss and gnrh mRNAs in teleost fish have demonstrated increased expression during the reproductive cycle. Interestingly, like mammalian species kisspeptin mediates the positive feedback effect of sex steroids in sexually mature fish including medaka and goldfish. In several teleosts, pharmacological administration of synthetic kisspeptin peptides affects gene expression of gnrh1, fshβ and lhβ, and also induces gonadal development in immature fish, suggesting their possible application in captive reproduction. This review highlights the importance of selection of suitable mature peptides of fish kisseptins for induced maturation in captivity.

Cochicó belongs to “Encadenadas del Oeste” system of lakes being a typical water body of the Pampas region. The most abundant fish species in this lake is the pejerrey (Odontesthes bonariensis) valued due to the quality of its flesh and as a game fish. The aim of this study was to compare the gonadal stages of pejerrey during two consecutive spawning seasons (August to December) in relation to sexual steroids and temperature in this lake. In general, pejerrey gonadal development, the Gonadosomatic index and the plasma levels of estradiol and testosterone fluctuated in relation with temperature. In 2014 samplings, females started to ovulating in early August, with a peak during September-October and ending in December with many of them with atretic oocytes. However, in 2015, a marked delay in maturation was observed with ovulated fish only in October and December. This fact may be because the minors mean temperatures recorded in this year. For males, it was possible to find spermiating animals during the whole spawning season and only arrested animals in December. Unexpectedly, histological gonadal analysis revealed for the first time pejerrey with testis-ova, probably due to the intensive use of agrochemicals in this region. Fil: del Fresno, Pamela Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; Argentina Fil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentina Fil: Berasain, Gustavo Emilio. Ministerio de Desarrollo Agrario de la Provincia de Buenos Aires; Argentina Fil: Miranda, Leandro Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; Argentina

Gonad development is a highly regulated process that coordinates cell specification and morphogenesis to produce sex-specific organ structures that are required for fertility, such as testicular seminiferous tubules and ovarian follicles. While sex determination occurs within specialized gonadal supporting cells, sexual differentiation is evident throughout the entire organ, including within the interstitial compartment, which contains immune cells and vasculature. While immune and vascular cells have been traditionally appreciated for their supporting roles during tissue growth and homeostasis, an increasing body of evidence supports the idea that these cell types are critical drivers of sexually dimorphic morphogenesis of the gonad. Myeloid immune cells, such as macrophages, are essential for multiple aspects of gonadogenesis and fertility, including for forming and maintaining gonadal vasculature in both sexes at varying stages of life. While vasculature is long known for supporting organ growth and serving as an export mechanism for gonadal sex steroids in utero, it is also an important component of fetal testicular morphogenesis and differentiation; additionally, it is vital for ovarian corpus luteal function and maintenance of pregnancy. These findings point toward a new paradigm in which immune cells and blood vessels are integral components of sexual differentiation and organogenesis. In this review, we discuss the state of the field regarding the diverse roles of immune and vascular cells during organogenesis of the testis and ovary and highlight outstanding questions in the field that could stimulate new research into these previously underappreciated constituents of the gonad.

Psilorhynchus homaloptera mainly inhabits turbulent waters in the lower reach of the Yarlung Zangbo River, Tibet, China, and it is the only species of Psilorhynchus in China. However, many important aspects of its biology remain poorly documented, which hinders the conservation efforts. Therefore, we studied its reproduction using 801 specimens from the Motuo sector of the lower Yarlung Zangbo River from December 2015 to November 2016. The sex ratio was 0.68:1 (male:female) for the overall population. Females reached a larger total length and weight (134 mm and 18.6 g) than males did (113 mm and 12.2 g). Lengths at maturity were estimated 80.0 mm for males and 93.1 mm for females. Our analyses of gonad development and the size distribution of oocytes suggest that P. homaloptera is a single spawner with the peak spawning period between September and October. Furthermore, the estimated mean absolute fecundity was 557±204 eggs per fish, and mean relative fecundity was 50.9±10.9 eggs per g of female weight. The fecundity of P. homaloptera increased linearly with increasing total length, total weight, ovary weight, and age. This study on the reproductive biology of P. homaloptera demonstrates that the fish was in a vulnerable state due to the increasing anthropogenic activities in the lower Yarlung Zangbo River.

There is increasing pressure to develop alternative ecotoxicological risk assessment approaches that do not rely on expensive, time-consuming, and ethically questionable live animal testing. This study aimed to develop a comprehensive early life stage toxicity pathway model for the exposure of fish to estrogenic chemicals that is rooted in mechanistic toxicology. Embryo-larval fathead minnows (FHM; Pimephales promelas) were exposed to graded concentrations of 17α-ethinylestradiol (water control, 0.01% DMSO, 4, 20, and 100 ng/L) for 32 days. Fish were assessed for transcriptomic and proteomic responses at 4 days post-hatch (dph), and for histological and apical end points at 28 dph. Molecular analyses revealed core responses that were indicative of observed apical outcomes, including biological processes resulting in overproduction of vitellogenin and impairment of visual development. Histological observations indicated accumulation of proteinaceous fluid in liver and kidney tissues, energy depletion, and delayed or suppressed gonad development. Additionally, fish in the 100 ng/L treatment group were smaller than controls. Integration of omics data improved the interpretation of perturbations in early life stage FHM, providing evidence of conservation of toxicity pathways across levels of biological organization. Overall, the mechanism-based embryo-larval FHM model showed promise as a replacement for standard adult live animal tests.

Larkinia grandis (Broderip & G.B. Sowerby I, 1829), an important fishing resource for Mexican communities, is an Arcidae clam. It is also considered a species with aquaculture potential. In this work we investigated the gonadal phases and sexuality in a population of L. grandis in the Gulf of California. Our findings support the hypothesis that there is one male per female in the population studied. It also documents that the shape, position and color of the gonads of L. grandis are consistent with observations in other Arcidae species. Additionally, five gonadal phases are differentiated and described in males and females (development, mature, spawning, post-spawning and resting), with a noticeable presence of brown cells during post-spawning and the onset of the resting phase, suggesting that those cells are involved in the reabsorption of remnants. Additionally, asynchronous gametogenesis in males, synchronic gametogenesis in females and batch spawning are defined. The results of this contribution can be used in the efforts to protect this bivalve.

We evaluated how genotype (stock source, parental line, chromosomal sex) and temperature interact to influence gonad development and phenotypic sex of Oncorhynchus mykiss. Embryos were generated from single pair matings of natural-origin and first-generation hatchery-origin O. mykiss held at ambient or elevated (5 °C above ambient) water temperature. Exposure to elevated temperature lasted from fertilization until the onset of exogenous feeding, after which all experimental groups were maintained at ambient temperature. Sexual phenotype was determined by histology and sexual genotype by the OmyY1 marker. There was 99% concordance among fish sexed both phenotypically and genotypically, demonstrating that experimental factors, including elevated rearing temperatures, did not result in sex change. Approximately 10% of the histologically examined fish showed no evidence of gonad development beyond the indifferent stage. Most of these fish were from hatchery family lines.

Giant prawns (Macrobrachium rosenbergii) need enough nutrients for the reproductive process. One way to give feed which contains high enough protein. Complete nutritional content, especially protein, can be found in natural food. The type of natural feed used for main feeds including squid, sea worms, trash fish. Complete nutrient content can affect the rate of gonadal development and fecundity. (Squid, sea worms, trash fish) on the level of gonadal maturity and density of broodstock parents (Macrobrachium rosenbergii). This research was conducted by a completely randomized design (CRD) trial design. This study used 4 replications of different types of feeding. The types of feed given are squid, sea worms, trash fish, and pellets at a dose of 5% from biomass/day. The parameters of observation include observation of the level of gonad resistance, fundamentality of broodstock parent, and measurement of water quality (temperature, pH, and dissolved oxygen). The results showed that the administration of different types of feed (sea worms, trash fish) had a very significant effect on the level of maturity and had a significant effect on the probability of prawns (M. rosenbergii). After analysis of variance, the results of F Calculations are greater than F Table 0.05 and F Table 0.01. The smallest significant difference test (LSD) was obtained in P1 (Squid feed) with the Gonad maturity rate ± 5- 6 days as much as 83 % parent and fecundity average results of 28,846 ± 4,925.3 thousand / 45 g.

The objective of this study was to determine the optimum dose of melastoma Melastoma malabathricum leaf extract that can inhibit the gonad development of Nile tilapia and increase its growth rate. This study used a completely randomized design containing five extract dose treatments (0, 0.5, 1, 2, and 4 g/kg diet doses) and three replications. The undifferentiated Nile tilapia larvae (7 days post hatching) were randomly distributed (n=30) to fifteen aquaria (100×50×50 cm3) and maintained for 112 days using a common recirculation system. The results showed that all dose treatments were not significantly different (P>0.05) in gonadosomatic index values of the D84 and D98 samplings. However, the 1 g/kg diet (D112) was significantly different (P0,05) terhadap nilai GSI pada sampling D84 dan D98. Namun, perlakuan 1 g/kg pakan pada sampling D112 berbeda nyata (P

Phenanthrene (PHE) as a tricyclic polycyclic aromatic hydrocarbon is one of the common pollutants in water and sediments, which can cause reproductive toxicity to aquatic organisms. In this study, enzyme-linked immunosorbent assay (ELISA) was used to detect the vitellogenin (VTG) of loach, and then to explore the estrogenic toxicity effect of PHE on loach. The results were as follows: (1) with the increase of PHE concentrations and the extension of exposure time, the gonadosomatic index (GSI) of males decreased significantly, while it increased in female loaches. In addition, males had more obvious changes than females and were more sensitive to PHE. (2) The increase of VTG contents in serum of males were stronger than that in females. Those results reveal that PHE has estrogenic effect, which can affect the generation of VTG, thus causing damage to the gonad development of loach.

Aegla castro, is an endemic anomuran crab from Brazil found in headwater streams of the Atlantic Forest on the Paranapanema River basin. This study aims to evaluate the gonadal maturity of A. castr...

The sea cucumber Apostichopus japonicus is dioecious, with seasonal reproduction. G protein-coupled receptor (GPCR)-mediated signaling systems might play critical roles in the reproductive control of A. japonicus. Here, we classified GPCR from the genome in silico and used transcriptomic analyses to further mine those that function in gonadal-development control. Totally, 487 GPCRs were predicted from A. japonicus, and 183 of these were further annotated to molecular pathways. Transcriptome analysis revealed 327 GPCRs expressed in gonads, and these were classified into four families and 19 subfamilies. Three pathways were apparently associated with reproduction, including neuroactive ligand-receptor interaction, the mTOR and Wnt signaling pathways. Seven and eight ovary- and testis-specific GPCRs were filtered, and the gene expression profiles were determined in multiple tissues and gonads at different developmental stages by qPCR. These results provide new insights into the discovery of GPCR-mediated signaling control in sea cucumber reproduction, especially in gonadal development control.

The dynamics of physiological and biochemical parameters of blood and urine in the process of gonad maturation in females of the sterlet × beluga hybrid (Acipenser ruthenus L., 1758 × Huso huso L., 1758) grown using CWSI technology is studied. It is shown that, when this technology is applied, features in functional changes that accompany the gonadogenesis of female hybrids appear, distinguishing them from those of fish from natural populations. At the same time, the direction of the generative exchange aimed at the formation of gametes is generally the same as in females from natural populations. However, the evidence of this process, reflecting its intensity at different stages of gonad development, is not as distinct as in females migrating to spawn. Possible reasons for high levels of the studied physiological and biochemical parameters in blood of females of the hybrid after the end of their artificial wintering are discussed.

The biological zero of gonadal development and the effective accumulated temperature of one and two-year-old razor clams Sinonovacula constricta (Lamarck 1818) were studied in Sanmen County, Zhejiang Province, China between April 2016 to October 2017, using a new variety named “Shen-Zhe No. 1”. The biological zero was determined by using the rule of effective accumulated temperature and the linear regression method, which was confirmed using a histological analysis of the full gonadal development cycle. The results showed that the biological zero of gonadal reproduction of 1-year-old and 2-year-old S. constricta was the same: 20.8 °C. When the temperature reached 20–21 °C, analysis of the histological sections indicated that more than half of the S. constricta individuals initiated gonadal development. The average effective accumulated temperature over two years was 806 d °C. This study contributes to our understanding of the regulation and control of gonadal maturation, suggesting that changes in the spawning and breeding season during one-year of farming using the new variety of razor clam could provide an economic benefit to industrialized large-scale spat production. The results demonstrated that the razor clam S. constricta is a typical clam of the accumulative temperature mature oviposition type. In addition, although S. constricta does not display hypothermy, it requires a lower temperature for gonadal maturity and spawning.

Background. The sailfish Istiophorus platypterus is a viviparous billfish species, it is caught by trolling in the sports fishery in Mexico. However, to date, there has been no reproductive biology studies of sailfish in Acapulco Bay, although the reproductive aspects of any species represent essential information for the design of management plans. Goals. Estimate the spawning frequency and batch fecundity to quantify reproductive characteristics of sailfish in waters off Acapulco, Bay. Methods. During the period 2008–2019, a total of 581 fish were sampled. Macroscopy analysis and quantitative histology was used to describe reproductive characteristics of the sailfish gonads. Results. 55.8% of the organisms analyzed were males, the remaining 44.2% were females, the sex ratio (1.26 M: 1 H) was different from the expected theoretical ratio (X2 = 7.53). The ovaries of 155 females were classified into five ovarian development phases based on histological analysis of the most advanced group of oocytes. Sailfish are multiple spawners with asynchronous oocyte development. Batch fecundity for 14 females with the presence of hydrated oocytes but without postovulatory follicles ranged 0.330 to 2.092 × 106 eggs with an average of 1.07 × 106 eggs. Gonadosomatic indices (GSI) indicated that sailfish have a reproductive period with peaks in August and October (mean monthly GSI= 4.3% and 5.4%). Conclusions. Population sailfish in Acapulco Bay is composed of males and females in similar proportions, with a gonadal development by groups that can be described in five development phases, a reproductive maximum during the warm months of the year and a relatively high fecundity.

The reproductive strategy of the non-native predator cichlid Cichla kelberi was determined to explain its success after more than 60 years of being introduced into an isolated reservoir in southeastern Brazil. This was one of the first known translocations of the genus Cichla out of its natural range. Macro and microscopy characteristics of the gonadal development stages and the maturation phases were described, along with the reproductive features (size at first maturation size, gonadosomatic index and sex ratio). We hypothesized that the stable conditions of the reservoir, with low connectivity, weakly defined spatial gradient, and slight seasonal changes in environmental variables favour the equilibrium strategy that enable predators to have high offspring survivorship because of great parental investment in individual progeny. Sex ratio was well balanced with males and females reaching first maturity between 30.0 and 28.6 cm total length (LT ), respectively. The stages of oocytes (primary and secondary growth, vitellogenic and atresia) and spermatocytes (spermatogonia, spermatocytes, spermatids and spermatozoa) development were identified. Five phases of gonadal development (immature, developing, spawning capable, regressing and regenerating) were described for both sexes. A long reproductive season was found, with spawning peaks in August/September and, to a lesser extent, in April/May. Parental care and spawns in parcels (batch spawns) corroborated the raised equilibrium strategy that was effective in this isolated reservoir. This species developed reproductive mechanisms that fit to different environmental conditions, with multiple spawning being associated with lentic environments and asynchronous development of oocytes, which are released over long periods. The reproductive plasticity in reservoirs may be one of the main factors inherent to the successful of colonization and establishment of the peacock bass in the environments in which they were introduced. This article is protected by copyright. All rights reserved.

Background Gonad development and differentiation is an essential function for all sexually reproducing species, and many aspects of these developmental processes are highly conserved among the metazoa. However, the mechanisms underlying gonad development and gametogenesis remain unclear in Tridacna squamosa, a large-size bivalve of great ecological value. They are protandrous simultaneous hermaphrodites, with the male gonad maturing first, eventually followed by the female gonads. In this study, nine gonad libraries representing resting, male and hermaphrodite stages in T. squamosa were performed to identify the molecular mechanisms. Results Sixteen thousand four hundred ninety-one unigenes were annotated in the NCBI non-redundant protein database. Among the annotated unigenes, 5091 and 7328 unigenes were assigned to Gene Ontology categories and the Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway database, respectively. A total of 4763 differentially expressed genes (DEGs) were identified by comparing male to resting gonads, consisting of 3499 which were comparatively upregulated in males and 1264 which were downregulated in males. Six hundred-ninteen DEGs between male and hermaphroditic gonads were identified, with 518 DEGs more strongly expressed in hermaphrodites and 101 more strongly expressed in males. GO (Gene Ontology) and KEGG pathway analyses revealed that various biological functions and processes, including functions related to the endocrine system, oocyte meiosis, carbon metabolism, and the cell cycle, were involved in regulating gonadal development and gametogenesis in T. squamosa. Testis-specific serine/threonine kinases 1 (TSSK1), TSSK4, TSSK5, Doublesex- and mab-3-related transcription factor 1 (DMRT1), SOX, Sperm surface protein 17 (SP17) and other genes were involved in male gonadal development in Tridacna squamosal. Both spermatogenesis- (TSSK4, spermatogenesis-associated protein 17, spermatogenesis-associated protein 8, sperm motility kinase X, SP17) and oogenesis-related genes (zona pellucida protein, Forkhead Box L2, Vitellogenin, Vitellogenin receptor, 5-hydroxytryptamine, 5-hydroxytryptamine receptor) were simultaneously highly expressed in the hermaphroditic gonad to maintain the hermaphroditism of T. squamosa. Conclusion All these results from our study will facilitate better understanding of the molecular mechanisms underlying giant clam gonad development and gametogenesis, which can provided a base on obtaining excellent gametes during the seed production process for giant clams.

Gonadotropin-inhibitory hormone (GnIH) plays a critical role in regulating gonadotropin-releasing hormone (GnRH), gonadotropin hormone (GtH), and steroidogenesis. The Lpxrfa (the piscine ortholog of GnIH) system has been found to regulate fish reproduction. To gain insight into the role of Lpxrfa in the regulation of spotted scat (Scatophagus argus) reproduction, spotted scat Lpxrfa (ssLpxrfa), and its receptor (ssLpxrfa-r) were cloned and analyzed. Tissue distribution and expression patterns at the hypothalamo-pituitary-gonadal axis (HPG axis) of sslpxrfa and sslpxrfa-r mRNA were also investigated during gonadal development of spotted scat. The open reading frame (ORF) of the sslpxrfa was 606 bp encoding 201 amino acids and includes a putative signal peptide and two mature ssLpxrfa peptides with LPXRFamide motif at their C-terminus. The sslpxrfa-r ORF was 1449 bp encoding 482 amino acids and contracted a seven-hydrophobic transmembrane (TM) domain structure. The tissue distribution showe d that the sslpxrfa was highly expressed in hypothalami, gill, and the gonads. In addition, sslpxrfa-r was highly expressed in hypothalami, pituitaries, and the gonads. Quantitative real-time polymerase chain reaction (qPCR) revealed that sslpxrfa had the highest expression in the hypothalami and pituitaries, and the lowest expression in the gonads in stage V. During gonadal development, the expression of sslpxrfa-r was gradually increased in the hypothalami but reduced in the gonads. However, no obvious trend was observed in the pituitaries. The expression of sslpxrfa and sslpxrfa-r decreased significantly after injection with 17β-estradiol (E2). However, the expression of both sslpxrfa and sslpxrfa-r was not changed after injection with 17α-methyltestosterone(17α-MT) in the hypothalami. In addition, no changes were observed in the expression of fshβ and lhβ in the pituitaries after injecting ssLpxrfa-1. However, ssLpxrfa-2 could downregulate the expression of sbgnrh and fshβ in the hypothalami and pituitaries, respectively. Taken together, these findings suggested that ssLpxrfa may participate in E2 feedback in reproduction and regulate the reproductive axis of spotted scat.

The P-element induced wimpy testis (Piwi) proteins, which are associated with PIWI-interacting RNAs (piRNAs), play important roles in meiosis, germ cell division, and germline maintenance. In this study, we identified and characterized the Paralichthys olivaceus piwil2 gene, a constituent factor of the piRNA pathways involved in the biogenesis of reproductive development. The biological analysis indicated that piwil2, which contains PAZ and PIWI domains, was highly conserved between teleosts and tetrapods. The piwil2 distribution profile in different tissues confirmed a sexually dimorphic expression pattern, with a higher expression level in testis. In situ hybridization demonstrated that piwil2 was expressed in the oogonia and oocytes of the ovaries as well as in the Sertoli cells and spermatocytes of the testes. Gene piwil2 showed a maternally inherited expression pattern during embryonic development, and was highly expressed during the early embryonic development. Different luciferase reporters were constructed to determine the transcriptional regulatory mechanisms of piwil2. The piwil2 core promoter region was located at −360 bp to −60bp. Furthermore, some representative sex hormones, including human chorionic gonadotropin, 17α-methyltestosterone, and estradiol-17β had distinct regulatory effects on piwil2. In a summery, these results indicate that piwil2, regulated by sex hormones and transcriptional elements, has vital functions in the reproductive cycle and gonadal development.

This study analyzed the tissue indices, proximate composition, fatty acid and amino acid composition of edible tissues of male E. sinensis under three feeding modes (formulated diets (FD), natural diets (ND), and traditional diets (TD)). The results showed that different feeding modes had no impacts on the overall gonadal development, as no significant difference was found in gonadsomatic index among three treatments. For edible yield, three modes all had similar levels of the meat yield, hepatosomatic index, and total edible yield. Although different feeding modes did not affect the individual edible yield and gonadal development, significant differences were detected in the nutritional composition of males from three modes. For proximate composition, significant differences were found in the total lipids of gonads and the carbohydrate of hepatopancreas and meat. For fatty acids, crabs from ND had a higher proportion of monounsaturated fatty acids. In gonads and hepatopancreas, FD had a higher proportion of long-chain polyunsaturated fatty acids. For amino acids, FD had higher amino acid contents, while ND had the lowest. Except tryptophan, the essential amino acids scores of the meat were all greater than 100. As there was no significant difference on meat quality and meat yields between three feeding modes, this study suggests that the formulated diet could replace the natural diet and traditional diet towards sustainable crab farming in future.

The present study was carried out to compare gonad development, oocyte maturation and fecundity of the spotted snakehead (Channa punctatus) fish during January to November 2015 in different water bodies (such as pond, Joghati baor and Bhairab river) in Jashore, Bangladesh. Mean GSI (gonadosomatic index) values of the female C. punctatus during January, March, May, July, September and November were significantly highest in pond, followed by those in Joghati baor and the lowest in Bhairab river. Absolute fecundity during the month of July in pond, baor and river was 30,006±2,027, 23,629±2,356 and 16,659±2,486, respectively, and the relative fecundity was 5064±183, 4865±106 and 4641±138 eggs, respectively. Mean ova diameter in pond, baor and river in March was 0.25±0.04 mm, 0.16±0.02 mm and 0.21±0.03 mm; in May was 0.36±0.03 mm, 0.29±0.03 mm and 0.23±0.04 mm; in July was 1.06±0.06 mm, 0.95±0.05 mm and 0.87±0.03 mm; and in September was 0.84±0.04 mm, 0.82±0.03 mm and 0.72±0.05 mm, respectively. Mean GSI values of the male C. punctatus during January, March, May, July, September and November were significantly higher in pond than those in baor and river, respectively. The mean highest GSI for female was found to be 6.06±0.11 in pond during the month of July, while the lowest GSI of 0.30±0.08 was in Bhairab river during November. The highest GSI value for male was obtained to be 0.70±0.16 in pond during the month of July, while the lowest GSI of 0.12±0.03 was found in Bhairab river during January. However, significant differences (P

Sex hormones play an essential role in sexual differentiation, maintenance of sexual characteristics, gamete maturation, and mating behavior. However, very little is known about their dynamics in molluscs. We conducted a study on sex hormone (17β-estradiol, testosterone, and progesterone) concentrations in male and female Strombus pugilis to identify their variations at different gonadal stages. A total of 90 organisms (30 per month) were collected in February, September, and November 2016. The gonadal digestive gland complex of each specimen was dissected and divided into two sections. One section was set in alcoholic Bouin's fluid and processed with classic histological techniques; the second was macerated with 80% ethanol to extract steroids and analyzed by enzyme immunoassays. Histological section analysis was used to classify gonadal development into three stages: gametogenesis, mature, and undifferentiated. Mature females were observed in September. Testosterone and 17β-estradiol concentrations in both sexes were highest in the mature stage. In S. pugilis, 17β-estradiol, progesterone, and testosterone were all present, with higher concentrations associated with reproductive activity.

In recent years, the increasing use of environmental endocrine disruptors has caused serious environmental pollution and hurt aquatic organisms. It is still risky for aquatic species and humans exposed to 17α-methyltestosterone (MT), however, the harmful effect of MT on fish is still poorly understood. The main purpose of this study is to evaluate the influence of MT on Pseudorasbora parva at multi-levels. We analyzed gonadal histology, the sex steroid hormones, steroidogenic genes expression, and transcriptome profiling of gonads in response to MT in adult P. parva. Through this study, we found MT could inhibit the gonadal development of P. parva, and the growth and development of fish could be delayed by exposure to MT at 200 ng/L. MT could produce disruption effects on fish from multiple pathways, while its interference to the HPGL axis happens primarily through the steroidogenic pathway, e.g., disturbing the expression of crucial genes and sex steroids synthesis. Besides, we constructed 4 RNAseq libraries and obtained 7758 and 11,543 DEGs in females and males, respectively. Interestingly, we found MT had more obvious disruption effects on males than the females, mainly reflected in the immune system. Interestingly, we found three common pathways in both sexes after MT exposure, i.e., cell adhesion molecules, cytokine-cytokine receptor interaction, and neuroactive ligand-receptor interaction. These results confirm the suitability of P. parva as a model fish for aquatic toxicological study and provide us a multidimensional sight for the disruption effects of MT on fish.

The first evidence of the impact of environmental contamination on populations of Protopterus aethiopicus (Heckel, 1851) in terms of body indices, cellular development (histology) and intersex cond...