A Model of Hormonal and Environmental Involvement in Growth and Sex Differentiation in European Eel (Anguilla Anguilla)

Growth in vertebrates is a complex interaction involving the development of cells, tissues and organs. Hormones regulating growth during maturation are involved mainly in the interaction between the somatic axis and the reproduction of brain-pituitary axes. Based on the results of hormone and gene transcriptions, the secretion and treatment controlling both the somatic axis and the gonadotropic axis were affected, directly or indirectly, by the environment parameter through hormones that were studied in my laboratory. A model was proposed for sex differentiation and gonadal development correlating to the growth of European eel (Anguilla anguilla). A high growth variation is affected by the environment. At a low density of eels, the gonadotropin-releasing hormone (GnRH) affected the secretion follicle stimulation hormone (FSH) in the pituitary, steroidogenesis and aromatase (CYP19) synthesis, and the 17β-estradiol (E2) from 11-ketotestosterone (Kt-11) causing ovary development. The ovary secretion E2 affecting the ade-nylate cyclase-activating polypeptide (PACAP), growth hormone (GH) and the insulin-like growth factor (IGF) stimulated rapid growth in females. On the other hand, a high density of eels caused the pituitary gland to secrete FSH at a lower level, and CYP19 was not synthesized in the gonads. The secretion of Kt-11 affected differentiation to testis, which inhibits the somatic axis in reducing growth rate.

Impact of xenoestrogens on sex differentiation and reproduction in teleosts

Among vertebrates,teleosts display a wide array of sex determination and differentiation mechanisms ranging from chromosomal sex determination on one end of the spectrum to environmental sex determination on the other end.However,the interplay of both these mechanisms is also not uncommon.Several gonochoristic fishes exhibit gonadal plasticity often resulting in sex reversal.The major manipulation of sex differentiation in teleost is affected by sex steroids.In this context,the increasing contamination of aquatic ecosystems by estrogen-like compounds,commonly known as xenoestrogens,is of major concern.This often leads to deleterious effects on the reproductive success of fish and thereby adversely impacts aquatic biodiversity.In the present review,we have focused on impact of xenoestrogen at different levels of the reproductive system influencing not only gonadal differentiation in teleosts but also their reproductive functions.The review would also explore the mitigation strategies and regulations in place for aquatic xenoestrogen management.

A landscape of differentiated biological processes involved in the initiation of sex differentiation in zebrafish

Zebrafish(Danio rerio)has been used as a promising animal model to study gonadal development and gametogenesis.Although previous studies have identified critical molecules participating in zebrafish gonad differentiation,a landscape view of the biological processes involved in this process is still lacking.Here we isolated intact zebrafish differentiating gonads,at 25 days post-fertilization(dpf)and 30 dpf and conducted RNA-seq analyses on the juvenile gonads that tended to develop into ovaries or testes.Our study demonstrates that the juvenile ovary and testis at 25 dpf and 30 dpf are different at the biological process level.During ovary differentiation,the biological processes related to metabolic activities in the production of energy and maternal substances,RNA degradation,and DNA repair were enriched.During testis differentiation,the biological processes related to cell proliferation,differentiation,and morphogenesis were enriched,with a total of 15 signaling pathways.Notably,we reveal that the immune-related processes are extensively involved in the regulation of testis development.Overall,this study provides a landscape of differentiated biological processes and novel insights into the initiation of sex differentiation in zebrafish.

A Review of Sexual Determination and Differentiation in Crustacean

The prerequisite for monosex culture is to elucidate the molecular mechanism of sex determination and differentiation in crustaceans, as well as to explore the key genes that play a role in this process. Monosex culture technology based on crustacean economic species is of great importance in terms of genetic breeding and economic benefits of aquaculture. As a result, study into the mechanisms of sex determination and differentiation in crustaceans not only contributes to the current absence of basic theories of crustacean sexual mechanism, but also encourages technical innovation in aquaculture to increase overall economic efficiency. This study synthesizes and evaluates available research on sex determination and differentiation in crustaceans, and then provides recommendations for future research objectives and priorities in the field.

Identification and Characterization of Long Non-Coding RNAs Involved in Sex-Related Gene Regulation in Kelp Saccharina japonica

Long non-coding RNAs(lncRNAs)regulate a variety of biological processes,including sexual reproduction and differentiation.Saccharina japonica,a commercially important brown alga in China,shows remarkable sexual dimorphism in haploid gametophytes.The sex of Saccharina japonica gametophytes is determined by UV sexual system.However,no results have been reported on the lncRNAs involved in the sex-related gene regulation of S.japonica.This study identified a number of lncRNAs and assessed their expression levels in male and female gametophytes.Among them,a total of 405 lncRNAs and 211 mRNAs showed differential expressions.Furthermore,the functions of target genes of differentially expressed lncRNAs(DELs)differed from those of differentially expressed genes(DEGs),suggesting that lncRNA may interact with other functional proteins,in addition to DEGs,to involve sex regulation in S.japonica.There were 32 and 90 potential cis-regulatory and trans-regulatory interactions between DELsDEGs,respectively.Five of these lncRNAs(LNC_002974,LNC_021059,LNC_038466,LNC_051584,and LNC_027400)interacted with putative male sex determination region(SDR)genes,suggesting that they act as regulators in gametophytes'sex regulation potentially.Findings from this study contribute to our understanding of the roles of lncRNAs in sex differentiation and lay the foundation for functional studies of candidate lncRNAs in the future.

Sex determination and dif ferentiation in Aurelia sp.1: the absence of temperature dependence

Cnidarians, being regarded as ‘basal' metazoan animals, are considered to have relatively high plasticity in terms of sex reversal. In this study we used an experimental approach to demonstrate sexual diff erentiation and plasticity in benthic polyps and pelagic medusae of A urelia sp.1 maintained at dif ferent temperatures. Results indicated that in A urelia sp.1, sex diff erentiation has been determined at the polyp stage and that all medusae originating from a given polyp are, phenotypically, of the same sex. In addition, the sex of polyps budding from the same clone(either male or female) at dif ferent temperatures appears to be the same as that of the parent. The sex of medusae that had originated from a known-sex polyp was observed to remain the same as that of the parent, irrespective of differences in strobilation or rearing temperatures. These results indicate that the mechanism of sex determination of Aurelia sp.1. is not influenced by prevailing temperature regimes. A comparison of variability in terms of sexual plasticity of A urelia sp.1 with that of Hydrozoa and Anthozoa suggests that species characterized by a free-swimming medusa life stage have a high dispersal potential, which probably results in a lower rate of sex reversal.

UBE2I stimulates female gonadal differentiation in chicken(Gallus gallus)embryos

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<0.05)under the overexpression of UBE2I and the sex-related genes(SOX9,DMRT1 and WT1)in females were downregulated(P<0.05)after interfering UBE2I.Furthermore,the change of UBE2I expression was associated with the level of estradiol and its receptors(AR and ESR),which suggests that UBE2I is necessary to initiate the female-specific development in chickens.In conclusion,this work demonstrates that UBE2I is a crucial sex differentiation-related gene in the embryonic development of chickens,which provides insights for further understanding the mechanism of sex determination in chickens.

Identification and Characterization of Gene SpDMRT99B and Its Sex-Biased Expression Profile in the Mud Crab,Scylla paramamosain

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.

Early embryonic transcriptomes of Zeugodacus tau provide insight into sex determination and differentiation genes

Zeugodacus tau(Walker)is an invasive pest.The sterile insect technique is an environment-friendly method for pest control.Understanding the mechanism of sex determination will contribute to improving efficiency of this technique.In this study,we identified the transformer(tra)gene in Z.tau.One female-specific and two male-specific isoforms of tra were found in Z.tau,and the male-specific splicing pattern of tra was found to occur 5 h after egg laying.We performed transcriptome sequencing at 1 h(E1),5 h(E5),and 9 h(E9)after egg laying and obtained high-quality transcriptome libraries of early embryo development.We identified 13297 and 11713 differentially expressed genes(DEGs)from E5 versus E1 and E9 versus E1 comparisons,respectively.To explore the potential functions of the DEGs during embryonic development,Gene Ontology,Clusters of Orthologous Groups of proteins,and Kyoto Encyclopedia of Genes and Genomes analyses were performed.Twenty-six genes potentially involved in sex determination or differentiation,including Maleness-on-the-Y(MoY),were identified in Z.tau.To verify the transcriptome results,15 genes were selected for quantitative real-time PCR validation.The results were consistent with the transcriptome sequencing results.Moreover,U2 small nuclear riboprotein auxiliary factor(U2AF-50),female lethal d(fl(2)d),and virilizer(vir)were highly expressed at E5,indicating that they may be related to the sex-specific splicing of tra.Further functional analysis is needed to confirm this speculation.Our data provide an insight into the mechanism underlying sex determination and differentiation in tephritid species.

Effects of Light-Emitting Diode (LED) Red and Blue Light on the Growth and Photosynthetic Characteristics of <i>Momordica charantia</i>L.

With andromonoecious Momordica charantia L. (bitter gourd) as material, three light qualities (50 μmol·m-2·s-1) including white LED light (WL), blue monochromatic light (B, 465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the stomatal conductance (GS) of leaves, significantly improved the net photosynthetic rate (Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (Pmax), apparent quantum efficiency (AQE) and light saturation point (LSP), and reduced the dark respiration rate (Rd) and light compensation point (LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that Momordica charantia is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.

Self-fertilization in a gonochoristic fish yellow catfish

Sex control techniques are in great demand for aquaculture because of the huge benefits of mono-sex production.In a previous study on yellow catfish(Tachysurus fulvidraco),intersex individuals were produced by administrating 17α-methyltestosterone(MT)or aromatase inhibitor letrozole(LZ).The ovarian and testicular portions of intersexual gonads developed well and were completely separated,arousing our interest in producing self-fertilizable fish and clone-like fish populations.In this study,yellow catfish fry were treated with a combination of MT and LZ at a low dose(5 mg kg^(-1)MT,300 mg kg^(-1)LZ)at a low water temperature(27.0℃,mixed sex-producing temperature,LL group)and a high temperature(33.5◦C,male-producing temperature,HL group),and with a high dose(10 mg kg^(-1) MT,600 mg kg^(-1) LZ)at a low water temperature(LH group),during 12-65 days post-hatching,the critical period of sex differentiation.Both XX and XY intersex were produced with different percentages at the same time through co-treatment with MT and LZ,with or without the help of male-producing temperature.The highest percentage of XY intersex(53%in XY,36%in XX and XY)and XX intersex(47%in XX,25%in XX and XY)was produced in LH and HL groups,respectively.Results of gonadal morphology,histology,and sperm dynamic analysis indicate that some XX and XY intersex individuals were capable of self-fertilization through artificial insemination.The reproductive performance of these intersex individuals was then investigated by injecting spawning agents,dissecting gonads,and artificially fertilizing eggs with their own sperm.The XX,XY,and YY genotypic individuals were produced by the self-fertilization of XY intersex individuals.The present study successfully produced high percentages of XX and XY intersex and conducted self-fertilization by mating the eggs and sperm of a single intersex individual.Self-fertilization in fish will show great potential in aquaculture genetics and breeding,for example,generating highly homozygous(or"clonal")genetic material,producing mono-sex populations,and identifying unknown sex determination modes.In particular,the cloning method of producing genetic materials will be greatly beneficial for maintaining advantageous traits through self-fertilization generation after generation.

A CCCH zinc finger gene regulates doublesex alternative splicing and male development in Bombyx mori

Recent identification of a Piwi-interacting RNA(piRNA)-initiated sex determination cascade in the silkworm,Bombyx mori,provides novel insights into high diversity of insect sex determination pathways.In this system,the W-chromosome-derived Fem piRNA is the primary sex determination signal.A CCCH-type zinc finger gene Masculinizer(Masc),which is targeted by Fem piRNA-PIWI complex in female animals,is indispensable for male-specific splicing of B.mori doublesex(Bmdsx).Although many genes involved in this cascade have been identified,the regulatory mechanisms of silk-worm sex determination remain to be elucidated.Here we show that another CCCH-type zinc finger gene,Bmznf-2,is a masculinization factor in B.mori.Bmznf-2 shows testisabundant expression and loss of Bmznf-2 function via clustered regularly interspaced short palindromic repeats 1 single-guide RNA-mediated mutagenesis results in feminized differentiation and appearance of the female-specific splicing variants of Bmdsx transcripts in males.In contrast,there is no phenotypic consequence in mutant females.In mutant males,relative messenger RNA expression levels of female-dominant genes such as vitellogenin and sex-specific storage protein I are significantly clevated while several male-dominant genes are significantly down-regulated.Furthermore,male mutants show delayed developmental timing,smaller body sizes of larvae and malformation of moth wings.Our data thus reveal that Bmznf-2 plays an indispensable role in silkworm male sexual differentiation.

Sex-biased gene discovery from the gonadal transcriptomes of the large yellow croaker(Larimichthys crocea)

The investigation of sex determination in fish is not only of great scientific value,but also has important practical significance,especially in fishes grown in aquaculture exhibiting obvious growth-related sexual dimorphism,such as the large yellow croaker(Larimichthys crocea).While growth of the female large yellow croaker is faster than that of the male,little information exists on the mechanisms that drive the differentiation of the testis and ovary in this species.In this study,the gene expression profiles of large yellow croaker testis and ovary were analysed using RNA-Seq technology.A total of 222 million reads were mapped to the reference genome(89.80%).The differential gene expression analysis identified 13 genes specifically expressed in ovary and 897 specific to testis.Among these,were candidate sex determining genes,such as Dmrt1,Gsdf,Sox9,Amh.This study explored gene expression profiles in large yellow croaker gonads at the transcriptome level by RNA-Seq technology.We found many DEGs related to the development of each specific organ,including the candidate testis differentiation genes Dmrt1,Gsdf,Sox9,Sox3,Amh and ovary differentiation gene Foxl2 by analogy with other fish species,providing essential foundation clarifying the molecular mechanism involved in early sex differentiation.

Investigation on Azoospermia Factor (AZF) Microdeletion and Sex-determining Region Y (SRY) of the Y Chromosome in Male Infertility

Objective To determine the incidence of azoospermia faetor （AZF） microdeletions of Y chromosome in male infertility and to investigate the mechanism of sex-determining region Y （SRY） in sex differentiation. Methods The mierodeletion of AZF was detected by multiplex polymerase chain reaction （PCR） using Y-chromosome specific sequence tagged sites （STSs）, and SRY was analyzed by PCR and sequencing. Results There were 100 cases with AZF microdeletion and the ratio of AZF microdeletion was 6.8% over all 1 474 cases. The ratios of AZF microdeletion of azoospermia group and severe oligozoospermia group were 9.0% and 7.1%, respectively, which was significantly different from oligozoospermia group （P〈 0. 05）. There were 67 cases with 5 STSs mierodeletion of sY152, sY239, sY243, sY254 and sY255. There were 20 cases with long fragment deletion more than 10 STSs, and the patterns of AZF microdeletion in other 13 cases were rare. In all 9 patients with disorders of sex differentiation, there were 6patients with SRY-absent and AZF-absent. There was no mutation of SRY gene by sequencing in other 3 patients with SRY-positive. Conclusion Deletions in AZF region of Y chromosome are specific with diagnoses with spermatogenesis disorder. Deletions of sY152, sY239, sY243, sY254 and sY255 occur the most frequently. SRY was an important candidate gene of testis-determining factor （TDF） gene.

Dynamics of sexual development in teleosts with a note on Mugil cephalus

The process of sex determination(SD)and sex differentiation(Sd)with associated sex-specific behaviour in teleosts is brought about by genetic factors and environmental factors under the influence of chemical messengers.SD is initiated by inherited genes,which in turn influence Sd by the production of hormones.To understand the plasticity of SD in fishes,the functional role of genes must be clearly elucidated.During early development,the dimorphic expression of male and female are mediated by the differentially sexualized brain.In mammals,SD region(SDR)on the Y chromosome(SRY)can be considered as male-specific copy of SOX3 and in the absence of SRY in teleosts suggests SD might be regulated by alternate genes.DM(doublesex/mab)-related genes,AMH(anti-mullerian hormone),TGF-b(transforming growth factor beta),GSDF(gonadal soma derived growth factor)and other genes(around 18)located in chromosomes of teleosts are found to be responsible for SD.The SD gene,sdY(sexually dimorphic on the Y chromosome)has been detected in more than 15 salmonid species,and in medaka and tilapia SD system is governed by heterogametic mechanism.In mullet,Mugil cephalus Dor et al.identified 27 SDR genes and suggested to be potential candidate genes for SD.Recently whole-genome sequencing data were produced from mullet and assembled into a draft genome sequence in which>30 loci are potentially associated with SD.Further analysis is required to know the involvement of each sex-biased gene for its functional influence on sex.Investigators attempted to know the sex-linkage group in tilapia and found that 2 linkage group i.e.LG1 and LG22 show SD loci,whereas in mullet it was documented that LG8 is the SD loci.Rigorous study with all male population(YY)or knockout of male marker gene,might give conclusive understanding on SD in future.The review highlights the absence of genomic understanding of SD and SDR genes for futuristic direction of research.

Proteome landscape and spatial map of mouse primordial germ cells

Primordial germ cells(PGCs)are precursors of both male and female gametes as fundamental materials for organism development.The transcriptome,methylome,and chromatin accessibility profiles of PGCs in both mice and humans have been recently reported.However,little is known about the characteristics of PGCs at the protein levels,which directly exert cellular functions.Here,we construct landscapes of both proteome and 3D spatial distribution of mouse PGCs at E11.5,E13.5 and E16.5 days,the three critical developmental windows for PGCs'sex differentiation,female meiosis initiation and male mitotic arrest.In each developmental stage of PGCs,nearly 2,000–3,000 proteins are identified,among which specific functional pathways such as oxidative phosphorylation,DNA damage repair,and meiotic cell cycle are involved for different events during PGCs development.Interestingly,by 3D modeling we find that PGCs spatially cluster into around 1,300 nests in genital ridge at E11.5 and the nest number is not increased by the exponential proliferation of PGCs.Comparative analysis of our proteomic data with published transcriptomic data does not show a close correlation,meaning that the practically executive factors are beyond the transcriptome.Thus,our work offers a valuable resource for the systematic investigations of PGC development at protein level and spatial map.

Development and organisation of gonadal steroidogenesis in bony fishes - A review

Gonadal steroidogenesis is pivotal to synchronize various reproductive stages including sexual development,growth and maturation.In all vertebrates including teleost,steroidogenesis is triggered by the mobilization of cholesterol by steroidogenic acute regulatory protein from outer to inner mitochondrial membrane.Thereafter,the entire process occurs in endoplasmic reticulum or mitochondria wherein various steroidogenic enzyme genes play a crucial role.The onset of steroidogenesis during sexual development in teleost is essentially regulated by differential expression of several transcription as well as steroidogenesis-related factors.More specifically,the role of dmrt,sox9,sox3,other sox forms,ad4bp/sf-1,wt-1,foxl2,ftz-f1,gata4,gsdf,Activator protein-1,fgfs and growth factors and steroidogenic enzymes such as cytochrome P450aromatase(cyp19a1),hydroxysteroid 3β-dehydrogenase(hsd3b),hydroxysteroid 17β-dehydrogenase(hsd17b)have been well characterised.Recently,the role of pax2,THO complex(thoc),pentraxin(ptx)and few signalling molecules like wnt4/5 regulating teleostean steroidogenesis has been reported.In females,cyp19a1 appears to be critical as it converts androgens to estrogens during ovarian differentiation which suggests that estradiol-17βis indispensable for the event.Unlike females,males do not depend on testosterone for testicular determination,yet has a major role along with 11-ketotestosterone in testicular development and growth when compared to early testicular differentiation.In males,onset of sex determining or testis-related genes seems most essential.Considering these,the regulation of steroidogenesis is virtually critical at later stages.In view of this,several steroidogenic motifs pertaining to transcriptional regulation have been analysed in teleost,yet far below than the reports on mammals.In this context,the regulatory influence on HHG axis plays a critical role in teleost.Further,multiple gonadotropin-releasing hormones and duality of gonadotropins play a differential role in gonadal function.As for steroidogenic pathway,the synthesis of sex steroids predominantly usesΔ4,however,Δ5 pathway was also evident.The next aspect is shift in steroidogenesis that usually occurs in the maturing follicles during final oocyte maturation,yet such a mechanism is not clear in males.The review highlights the interactions of steroidogenic enzyme gene regulation in terms of HHG axis and other important transcription factors that are involved in the regulatory pathways as well as the influence of environmental and dietary factors by comparing both sexes to present a holistic view on steroidogenesis onset and organisation during gametogenesis in teleost.