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Ubiquitin C-terminal hydrolases (UCHLs) are a subset of deubiquitinating enzymes, and are involved in numerous physiological processes. However, the role of UCHLs during gonad development has not been studied in crustaceans. In this study, we have first cloned and analyzed expression profiling of Sp-uchl3 and Sp-uchl5 genes from mud crab Scylla paramamosain . The full-length cDNA of Sp-uchl3 is of 1804 bp. Its expression level in the ovary was significantly higher than in other tissues ( p < 0.01), and during gonadal development, its expression in both O1 and O5 stages was significantly higher than in the other three stages of ovaries ( p < 0.05), while in T3 it was higher than in the former two stages of testes ( p < 0.05). Meanwhile, the full-length cDNA of Sp-UCHL5 is 1217 bp. The expression level in the ovary was significantly higher than in other tissues ( p < 0.01). Its expression in ovaries was higher than in testes during gonadal development ( p < 0.05). The expression level in the O5 stage was the highest, followed by the O3 stage in ovarian development, and with no significant difference in the testis development ( p > 0.05). These results provide basic data showing the role of Sp -UCHL3 and Sp -UCHL5 in the gonad development of the crab., Competing Interests: The authors declare no conflicts of interest.

VASA is one of the important regulatory factors that determine the development of the reproductive system. However, no information on vasa gene from Pleocyemata Brachyura is available. By using Race, we obtained a full-length cDNA of Sp-vasa of the green mud crab Scylla paramamosain. The full-length (2,851 bp) cDNA of vasa encodes a peptide of 631 amino acids. Real-time PCR results indicated that the expression level of Sp-vasa in the growth stage of ovary was higher than in the maturation stage, and in stage I and II of testis, the expression level of Sp-vasa were higher than in stage III. By using in situ hybridization, Sp-vasa RNAs were detected in the large part of oocyte plasm in stage I, nucleus zone in stage III and perinuclear zone in stage V. As the size of oocytes increases during oogenesis, the signals change from strong to weak. In addition, in stage I and II of testis, the expression levels of Sp-vasa were higher than in stage III, and the hybridization intensity of Sp-vasa gene gradually increased during spermatogenesis from spermatogonia to spermatids. However, no hybridization signal was detected in spermatozoon. Real-time PCR and in situ hybridization were consistent. These findings suggest that Sp-vasa is likely to serve as a useful and specific marker for germ cell development of S. paramamosain.

On grounds of the especially limited numbers of identified gonad-specific or gonad-related genes of large yellow croaker Larimichthys crocea which may represent a major obstacle for the study of gonad development and sex differentiation, we initiated a sequencing program of Expressed Sequence Tags (ESTs) in large yellow croaker. In this study, we firstly constructed a normalized gonad cDNA library using the combination of SMART technique and DSN treatment. The titer of amplified cDNA library was 4.8x10(11) and the percentage of unique cDNA sequences of the library was 82.49%. 2916 unique cDNAs were clustered from the 3535 high quality ESTs. Among the 1785 ESTs which had significant homology with known genes in the NCBI database, about 64 significant gonad-related genes were found, accounting for 3.59% of the total unique cDNAs. Specifically, the testis-specific LRR gene and testis-specific chromodomain Y-like protein gene were identified from fish for the first time. Six gonad-related microsatellite-containing ESTs were identified from the 129 ESTs containing 149 microsatellites. Expression patterns of 10 of these gonad-related gene homologues in ovaries and testes were examined by qRT-PCR. The results will be powerful resources for our further investigation to establish the molecular mechanisms of gonad development and sex differentiation in large yellow croaker., (2010 Elsevier Inc. All rights reserved.)

The feedback regulatory effects of estrogen (E2) and androgen (T) on the gonadotropin-releasing hormone (GnRH) and gonadotropin (GtH) within the brain–pituitary–gonad (BPG) axis in eels with undeveloped ovaries were investigated through in vivo studies. However, the regulatory role of the BPG axis only became apparent during ovary development in the migratory stage. To further elucidate the direct feedback regulation of the BPG axis, female Anguilla japonica underwent artificial induction of vitellogenesis, and the regulation of BPG axis tissues by GtH (human chorionic gonadotropin, hCG), E2, and T was explored through in vitro exposure. The mRNA expression levels of GnRH (mGnRH), GtH (fshb and lhb), and steroid biosynthesis enzymes (cyp11a1, hsd3b, cyp17a1, and cyp17a2) in the diencephalon, pituitary, and ovary, respectively, were determined. The results showed that the expression level of mGnRH in the diencephalon was significantly downregulated by 0.1 IU/mL hCG but upregulated by both 1 nM E2 and higher concentrations of T, suggesting a direct positive feedback regulation of E2 on mGnRH. In the pituitary, the expression levels of fshb and lhb were upregulated by E2, while fshb was suppressed by T. In the ovaries, the expression of cyp11a1 and hsd3b was upregulated by 1 nM E2, whereas T exposure resulted in an opposite effect. Cyp17a1 mRNA levels did not differ significantly with E2 treatment but were upregulated by 1 nM T. These findings suggest that low concentrations of E2 exhibited positive feedback regulation on all three levels (diencephalon, pituitary, and ovary) of the BPG axis, while T showed weaker and differential feedback regulation in BPG axis tissues. Overall, this study's results revealed the direct feedback regulation of hCG, E2, and T on the BPG axis in eels, a phylogenetic base of teleosts. [ABSTRACT FROM AUTHOR]

Sox genes encode transcription factors with a high‐mobility group (HMG) box, playing critical roles in the initiation and maintenance of a variety of developmental processes, such as sex determination and differentiation. In the present study, we identified 26 Sox genes in the genome of spinyhead croaker Collichthys lucidus (Richardson, 1844) with homology‐based analysis of the HMG box. The transcriptome‐based expression profiles revealed that the expression of the Sox gene in gonads began to differ between sexes when the body length was 2.74 ± 0.24 cm. At that time, three Sox genes (Sox11b, Sox8a and Sox19) were significantly upregulated, accompanied by the downregulation of 12 Sox genes in the ovary, and six Sox genes were temporarily significantly upregulated in the testis. Afterwards, the expression profile of Sox genes changed only with a small amplitude in both the ovary and testis. For adult tissues, huge differences were observed in the expression profiles of Sox genes between ovaries and testes, as well as small differences in somatic tissues between sexes. These results provide clues to further decipher the role of Sox genes in the processes of sex determination and differentiation in spinyhead croaker and other teleosts. [ABSTRACT FROM AUTHOR]

Abstract: A total of 5160 high quality ESTs (expressed sequence tags) averaging 357bp were collected from normalized cDNA libraries created from testis, ovary and mixed organs of mud crab Scylla paramamosain. Clustering and assembly of these ESTs resulted in a total of 3837 unique sequences with 576 overlapping contigs and 3261 singletons. Comparisons with the GenBank non-redundant (Nr) protein database (BLASTx, e-values <10−5) revealed putative functions or matched homologs from other organisms for 847 (22%) of the ESTs. Several gonad development related genes such as cathepsin C, thioredoxin peroxidase, vitellogenin receptor precursor, 50S ribosomal protein L24 and ubiquitin-conjugating enzyme E2 isoform 2 were identified from this EST project and demonstrated as gonad differential expression genes by rqRT-PCR. Sixty five different types of SSRs (simple sequence repeats) were identified from the total 411 EST-SSR motifs. A home-made cDNA microarray containing 5664 spots was developed and the hybridization results indicated that 39 unique transcripts were differentially expressed in testis and ovaries (P<0.05). The expression levels of eleven unique transcripts examined by rqRT-PCR were matched with microarray fairly. These results will provide a useful resource for functional genomic studies on the biology of reproduction of mud crab. [Copyright &y& Elsevier]

Toll-like receptors (TLRs) play essential roles in the innate immune system and have been extensively studied in mollusks. In this study, through a genome-wide search, TLR genes were identified as 29 in Haliotis discus hannai , 33 in H. rufescens , and 16 in H. laevigata. Domain analysis indicated that these TLR genes contain leucine-rich repeat (LRR) and Toll/IL-1 receptor (TIR) domains and exons ranging from 1 to 5. Polymorphism analysis showed that the TLRs in abalones did not have high diversities with 143 SNPs and no Indel in H. discus hannai , 92 SNPs and 3 Indels together with 6 missense mutations in H. rufescens , and no SNP or Indel in H. laevigata. The expression of 8 TLR genes in H. discus hannai was confirmed in the hepatopancreas, gill, hemolymph, gonads, intestine, muscle, and mantle. The expression of five TLR genes (out of 8) in gills (p < 0.05), three in hepatopancreas (p < 0.05), and three in hemolymph (p < 0.05) was upregulated separately in response to the infection caused by Vibrio parahaemolyticus. The findings in this study would contribute to a better understanding of the molecular immune mechanism of H. discus hannai against stimulation by V. parahaemolyticus and provide a basis for the study of TLRs in abalones. • 29, 33, 16 TLRs were identified from the genomes of Haliotis discus hannai H. rufescens and H. laevigata , separately. • Abalone TLR genes contain leucine-rich repeat (LRR) and Toll/IL-1 receptor (TIR) domains and exons ranging from 1 to 5. • 143 SNPs and no Indel in H. discus hannai , 92 SNPs and 3 Indels together with 6 missense mutations in H. rufescens , and no SNP or Indel in H. laevigata. • Vibrio exposure regulates the expression of TLRs in the gills, hepatopancreas, and hemolymph of H. discus hannai. [ABSTRACT FROM AUTHOR]

In our previous study, we found that the Spfoxl-2 transcript was highly expressed in gonads and explored its potential target genes in the ovary of Scylla paramamosain. In the current study, we primally analyzed its potential target genes in the testis through RNAi and RNA-Seq technology and compared with that in the ovary. The results showed that a total of 7892 unigenes were differentially expressed after Spfoxl-2 silencing in the testis, including plenty of conserved genes involved in testicular development, such as Dmrt family genes, Sox family genes, Caspase family genes, Cdk family genes, Kinesin family genes, Fox family genes and other genes. Further analysis revealed that these differentially expressed genes (DEGs) were enriched in crucial pathways involved in spermatogenesis, such as DNA replication, Cell cycle, Spliceosome, Homologous recombination, Meiosis and Apoptosis. The comparison results of potential target genes in the ovary and testis reveal 135 common potential target genes, including some genes involved in the immune response. According to our knowledge, the present work was the first to disclose the functions of foxl-2 in the testis of crustacean species using transcriptome analysis. It not only identifies key genes and pathways involved in the testicular development of S. paramamosain , but also reveals a new molecular-level understanding of the function of foxl-2 in testicular development. [Display omitted] • The foxl-2 was highly expressed in the testis of mud crab. • The knockdown of foxl-2 highly decreased the expression of genes involved in testis development. • The functions of foxl-2 in the testis and ovary are significantly different. • The knockdown of foxl-2 inhibits the expression of antimicrobial peptide genes in the testis and ovary. [ABSTRACT FROM AUTHOR]

• The expression of idmrt-2 was significantly higher in the testis than in the ovary. • The idmrt-2 regulates positively the expression of Dmrt-like and foxl-2 in testis. • The idmrt-2 enhances the expression of IAG in androgenic gland. The Dmrt (double-sex and mab-3 related transcription factor) gene family is considered to be a highly conserved gene family related to sex determination and sexual differentiation across species. In order to better understand the role of the idmrt-2 gene in gonad development in Scylla paramamosain , the idmrt-2 gene was cloned and analyzed. The cDNA contains a 1659 bp ORF region encoding 552 amino acids. The qRT-PCR results showed that idmrt-2 was significantly more expressed in the testis than in other tissues (p < 0.05). The expression of idmrt-2 was highest in the spermatids stage (T2 stage), followed by the mature sperms stage (T3 stage) and significantly higher than in the spermatocytes stage (T1 stage) (p < 0.05) during testicular development and the expression difference was not significant in different stages of ovarian development. RNAi studies revealed that after idmrt-2 was knocked down, the expression of Dmrt-like and foxl-2 genes in the testis decreased, as well as IAG expression in the androgenic gland. The findings suggest that idmrt-2 may be an IAG regulator and involved in testicular development. [ABSTRACT FROM AUTHOR]

Doublesex (Dsx) is a crucial member of the Dmrt gene family and plays a vital role in sex determination and differentiation among the animal kingdom. In the present study, a doublesex (designated as Spdsx) gene was identified and characterized for the first time in the mud crab, Scylla paramamosain. The Spdsx cDNA contains an 801 bp open reading frame (ORF) encoding 266 amino acids with a conserved DM domain. Meanwhile, to elucidate the conservation of Dsx, its orthologus were identified in several crustacean species as well. In addition, the expression pattern of Spdsx in various adult tissues and during embryo development was analyzed with qRT-PCR technology. Finally, the roles of Spdsx might play in the testis, androgenic gland, and ovary were analyzed by RNAi technology. The main results are as follows: (1) the Spdsx gene widely existed in analyzed crustacean species, and the multiple sequences alignment result indicated the conservation of Dsx was low except for the DM domain; (2) only one dsx gene was identified in analyzed crab and lobster, while 2 dsx genes (dsx-1 and dsx-2) were identified in shrimps; (3) the Spdsx gene was widely expressed in analyzed tissues, and the expression level in androgenic gland was obviously higher than that in other tissues. Interestingly, the expression level of Spdsx in the ovary was significantly higher than that in testis (p < 0.05); (4) The expression pattern of Spdsx during embryo development was divided into two groups: remained stable from blastula stage to 5 pairs of appendages stage; after 5 pairs of appendages stage, the expression level increased and remained stable from 7 pairs of appendages stage to hatching stage; (5) After the silencing of Spdsx , the expression level of marker genes in testis, ovary, and androgenic gland significantly changed, among which the expression level of vtg and vtgR in ovary down-regulated, the dmrt-like and dmrt-1a (exclusively expressed in testis) in testis up-regulated and the IAG in androgenic gland down-regulated. All the results above demonstrated that the Spdsx play crucial roles in regulating the reproduction system development of mud crab. [Display omitted] • The expression level of Spdsx in the ovary was significantly higher than that in testis. • The Spdsx positively regulate the expression of vtg and vtgR in ovary. • The Spdsx negatively regulate the expression of dmrt-like and dmrt-1a in testis. • The Spdsx positively regulate the expression of IAG in androgenic gland. [ABSTRACT FROM AUTHOR]

Fish cell lines are important for the study in resource conservation, genetic breeding, diseases control, and environmental pollutants detection. The establishment of gonadal cell lines will provide a suitable in vitro model for studying the molecular regulation mechanisms underlying sex determination and sex-related gene expression and function. Large yellow croaker (Larimichthys crocea) is the unique marine economic fish with the highest production in China's coastal waters. In this study, the continuous gonadal cell lines, ovary cell line of large yellow croaker (LYCO) and testis cell line of large yellow croaker (LYCT), derived from the ovary and testis of juvenile fish were established with modified Leibovitz's L-15 medium at 27 °C. The medium was perfected to improve the growth rate and the increment ability of the LYCO and LYCT. The characteristics of the two cell lines were investigated, including the concentration of zeta-life fetal bovine serum (FBS), different passage ratios, cryopreservation, and recovery. The cell lines were successfully transfected with pEGFP-N1 and pNanog-N1 by electroporation, and the transfection efficiency of cells was high; these results showed that the cell lines could be used to study the expression of exogenous and endogenous genes. The LYCO expressed the marker gene of ovarian follicle cells, Foxl2 , while the LYCT expressed the marker gene of testicular sertoli cells, Dmrt1. However, LYCO and LYCT did not express Vasa , a marker gene of germ cells. Therefore, LYCO and LYCT appeared to consist of ovarian follicle cells and testicular sertoli cells, respectively. After the knockdown of Dmrt1 and Foxl2 in LYCO and LYCT, respectively, the results showed that the cell lines could be effective for RNA-mediated interference (RNAi) experiments and the study of the interactions among genes. As a first fish gonadal cell lines of L. crocea, which can provide a new model for the interactions between somatic cells and germ cells, and a basis for the further study of their reproduction and breeding in L.crocea. The results lay a foundation for the study of the gonadal cell culture in marine fish in the future. • Two cell lines from the ovary and testis of large yellow croaker (LYCO and LYCT) were first developed. • LYCO and LYCT can be used for high-efficiency and rapid electroporation to induce transformation to study gene function. • Overexpression of Nanog in LYCO and LYCT laid a foundation for the study of endogenous gene expression. • It is the first time to report the relationship of the sex-related genes by Dmrt1 and Foxl2 knockdown in LYCO and LYCT. [ABSTRACT FROM AUTHOR]

• The Spfoxl2 was exclusively expressed in gonad. • The expression level of Spfoxl2 in the testis was significantly higher than that in the ovary. • The Foxl2 was highly conserved among crabs, while less conserved among analyzed other decapods. • The knockdown of Spfoxl2 mediated by RNAi technology repressed the expression of Spvtg in the ovary. Forkhead box protein L2 (Foxl2) is involved in multiple physiological processes, such as ovarian development, granulosa cell differentiation, ovarian follicle development, and oocyte growth. In this study, a Spfoxl2 gene encoded 530 amino acid protein with characteristic forkhead (FH) domain was identified from transcriptome data of mud crab Scylla paramamosain and validated the accuracy by PCR technology. Meanwhile, the orthologues of the Spfoxl2 gene in other 14 crustacean species were identified with the same method. Further multiple sequence alignment analysis revealed the Foxl2 was highly conserved, especially in the FH domain, even completely identical in several species. Besides, the semi-quantitative PCR (Sq-PCR) result showed Spfoxl2 gene was mainly expressed in the gonad (testis and ovary). Further quantitative real-time PCR (qRT-PCR) result demonstrated its expression level in the testis was significantly higher than that in the ovary (p < 0.01). In addition, the qRT-PCR result showed that in zoea V, megalopa, and larval I, the expression level of Spfoxl2 in megalopa is the highest. In addition, a putative Foxl2 binding site was identified on the promoter region of Spvtg , and knockdown of Spfoxl2 mediated by RNAi technology increased the expression of Spvtg in the ovary, suggesting Spfoxl2 might be the upstream negative regulator of Spvtg. Overall, this study provided new insights into the role of Spfoxl2 in ovary development through regulating Spvtg expression in S. paramamosain. [ABSTRACT FROM AUTHOR]

• 7 members of Dmrt gene family of Scylla paramamosain were identified based on transcriptome data. • Majority of dmrt genes were differently expressed between testis and ovary. • The dmrt_like gene was exclusively expressed in testis. • The dmrt-1a gene was exclusively expressed in gonad. • Different from many organisms, the expression of dsx gene in ovary was higher than that in testis. Doublesex and mab-3 related transcription factors (Dmrts) play crucial roles in sex determination/differentiation and gonad development. The information on Dmrts and their functions are still scarce in mud crab Scylla paramamosain. In this study, 12 published transcriptome data of S. paramamosain were retrieved, pooled, and assembled. From the assembly, 7 Dmrt gene family members were identified and consisted of Spdmrt-like , Spdmrt-1a , Spdmrt-3 , Spdmrt-11E , Spidmrt-1 , Spdoublesex (Spdsx), and Spidmrt-2. These dmrt genes were predicted to encode 224 aa, 465 aa, 435 aa, 276 aa, 520 aa, 552 aa, and 266 aa protein precursors, respectively. The expression patterns of the dmrt genes were characterized by semi-quantitative PCR. The Spdmrt-like and Spdmrt-1a were exclusively detected in gonads, of which both expression levels in the testis were higher than that in the ovary. The Spdmrt-3 , Spdmrt-11E , Spidmrt-1 , Spdsx , and Spidmrt-2 were observed in various tissues; all these genes were sexually dimorphic except for dmrt-11E. Specifically, the expression level of Spdmrt-3 and Spidmrt-2 were higher in the testis than that in the ovary. On the contrary, the Spdsx and Spidmrt-1 expression level were higher in ovary than that in testis. The present study's findings provided a fundamental understanding of Dmrt gene family members involving sex determination/differentiation and gonad development in the S. paramamosain. [ABSTRACT FROM AUTHOR]

• Full-length cDNA of SpSox9 was cloned and characterized from Scylla paramamosain. • The ortholog of SpSox9 identified from 16 decapoda crustacean species was highly conserved. • The expression of the Spsox9 was sexually dimorphic expressed in early gonad development. • The Spsox9 was mainly expressed in gonad (testis and ovary), eyestalk and cerebral ganglion. • The Spsox9 was highly expressed in 5 and 7 pairs of appendages, and eye-pigment formation stage. Sox9 gene, a crucial member of the Sox gene family, is present in various organisms and involved in many physiological processes, especially in sex determination and gonad development. In this study, we reported a sox9 gene (designated as Spsox9) from Scylla paramamosain through analyzing published gonad transcriptome data. Meanwhile, the accuracy was validated by PCR technology, and the 3′ sequences were cloned with 3′ RACE technology. The full-length cDNA of Spsox9 is 2843 bp, consisting of a 243 bp 5′ UTR, an 1124 bp 3′ UTR, and a 1476 bp ORF encoding 491 amino acids. Furthermore, to better understand its conservation among crustacean species, the sox9 gene ortholog was identified in several other crustaceans species with their published transcriptome data, respectively. All of the Sox9 proteins identified in the current study had the common feature of Sox proteins (HMG domain) and were highly conserved among analyzed crustacean species. In all examined tissues, the Spsox9 was mainly expressed in the gonad (testis and ovary), eyestalk, and cerebral ganglion. During embryo development, Spsox9 was highly expressed in 5 pairs of appendages, 7 pairs of appendages, and eye-pigment formation stage. During ovary development, the expression level of Spsox9 remained stable in the first 4 stages (O1-O4) and decreased in the tertiary vitellogenesis (O5) stage. During testis development, the expression level of Spsox9 was highest in the spermatid stage (T2) and was significantly different from that in the spermatocyte stage (T1) and mature sperm stage (T3) (p < 0.05). In addition, Spsox9 exhibited a sex-biased expression pattern in T1 and O1. These present results indicated that the Spsox9 gene might play crucial roles in the gonad and embryo development of mud crab. [ABSTRACT FROM AUTHOR]

The regulatory role of microRNAs in gonad development and reproduction is attracting more and more attention in recent years.Vitellogenesis−/Gonadal-inhibiting hormone (VIH/GIH) is a member of the crustacean hyperglycemic hormone (CHH) family. It plays a key role in regulating ovarian development and gonadal maturation in crustaceans. In this study, based on our preliminary studies of Spvih (Scylla paramamosain vih, Spvih), the regulation of expression of Spvih gene was further investigated. Predicted by bioinformatics software, we found that miR-34/miR-277 may play a regulatory role in Spvih expression. Analysis of luciferase activity of HEK293T cells transfected with the synthetic miR-34/miR-277 mimics and miR-34/miR-277 inhibitor revealed that miR-277 mimics significantly reduced the activity and miR-277 inhibitor significantly increased the activity compared to the control group. However, there was no significant difference in activity between miR-34 mimics and miR-34 inhibitor. The relative expression of Spvih and miR-277 was detected in the eyestalk, which had been injected with stroke-physiological saline solution(SPSS)and chemically synthesized miR-277 agomir and miR-277 antagomir, respectively. The results showed that compared with the control group SPSS, the expression of miR-277 in the eyestalk was increased significantly after miR-277 agomir injection, while the expression of Spvih was decreased significantly. After the injection of miR-277 antagomir, the expression of miR-277 in the eyestalk decreased significantly, while the expression of Spvih increased significantly. The inhibitory effect of miR-277 on Spvih expression was further verified. Based on miR-277 agomir and miR-277 antagomir injected into the base of the crab, the relative expression of the Spvtg gene in the ovarian and hepatopancreas was detected. The results showed that compared with the control group SPSS, the expression of Spvtg in the ovary and hepatopancreas were significantly increased after injection of miR-277 agomir, while the expression of Spvtg was significantly decreased after injection of miR-277 antagomir. Our study may provide an evidence of how miRNA works on the regulation of Spvih , which indirectly affects the ovarian development of mud crab, and suggest a new strategy for controlling crab reproduction. • It is the first time to report the relationship of miRNA and vih gene in crab. • By targeting the 3′UTR of the Spvih gene miR-277 could inhibit its expression. • miR-277 might be an efficient indirect regulator of vtg expression. • miRNA injection is a new strategy for induction the ovarian development in crab. [ABSTRACT FROM AUTHOR]

• Five Sox genes were first time identified from the genome of a species of crustacean, L. vannamei. • The five Sox genes had different sex biased expression in some tissues. • Sox21 , SoxB1 , and Sox14 had a higher expression in ovary than in testis. • Sox4 had a male-biased specific expression in gonad, hepatopancreas, gill and eyestalk. • Sox14 was high-expressed in early embryos, the other four Sox were high-expressed in late embryos. Sox transcription factors play essential roles in a variety of critical physiological processes. Still, members of the sox gene family have not yet been genome-wide identified in shrimps. In this study, a total of five members of the sox gene family were identified from the genome of Pacific white shrimp Litopenaeus vannamei and classified into three subgroups based on the conserved HMG-box domain. Among them, three belong to the SoxB subgroup (one in B1 and two in B2), one in the SoxC subgroup, and one in the SoxE subgroup. The five sox genes had different sex-biased expression in some tissues. Sox21 , soxB1, and sox14 had a higher expression in ovary than in testis. In comparison, sox4 had a male-biased specific expression in the gonad, hepatopancreas, gill, and eyestalk. There was no difference in soxE gene expression between testis and ovary. During embryonic development, the expression level of three sox genes (soxB1 , sox21 , and soxE) was higher in gastrulation stage compared to previous stages, declined in limb bud stage and then increased in intramembrane nauplius stage; the expression of sox4 was detected in blastula stage and continued to increase in the following two stages and then surged in intramembrane nauplius stage; the highest expression of sox14 was in the fertilized egg stage, and the expression level decreased with the development of the embryo. These results suggest that the shrimp sox gene family may be involved in gametogenesis, tridermogenesis, and neurogenesis. [ABSTRACT FROM AUTHOR]

• Full-length cDNA of SpSox14b and SpSox21 were cloned and characterized from Scylla paramamosain. • The expression of SpSox14b and SpSox21 had tissue and gender specificity. • SpSox14b was expressed in all tissues, while SpSox21 was only expressed in testis and brain. • SpSox14b and SpSox21 were high-expressed in the eye-pigment formation during embryogenesis. • WISH showed the SpSox14b and SpSox21 were mainly located in brain and eye areas in embryogenesis. Members of sox gene family play critical roles in development, and some of them have crucial functions in sexual dimorphism. To understand the role of two SoxB2 genes, Sox14b and Sox21 of mud crab Scylla paramamosain , the full-length 1939 bp SpSox14b cDNA sequence and 861 bp SpSox21 cDNA sequence were obtained from the crab's transcriptome database, which encode 397 and 259 amino acids respectively. The results of sq-PCR showed that SpSox14b was expressed in all tissues, while SpSox21 was only expressed in the testis and brain. qRT-PCR showed that the expression level of SpSox14b in ovary was significantly higher than that of testis, and during the gonad development its expression was the highest in O2 (previtellogenesis) stage. The expression level of SpSox21 in testis was much higher than in brain, and was significantly higher in T3 (the mature sperm stage) than in other stages of testis development. Meanwhile, in different stages of larval development, SpSox21 was low expressed in zoea, then increased significantly in megalopa. Therefore we speculated that SpSox14b and SpSox21 may play different roles in the gonad development of mud crab, especially SpSox21 may be involved in the development and maintenance of testis. The expression level of SpSox14b and SpSox21 during the eye-pigment formation was significantly higher than that in other embryonic development stages, the results of whole-mount in situ hybridization showed that SpSox14b and SpSox21 were mainly located near the head and the compound eyes in eye-pigment formation stage and hatching. It suggested that they may be involved in the formation of brain nerves and are related to the regulation of body segments, and play different roles in sexual dimorphism. [ABSTRACT FROM AUTHOR]