Ziping Zhang

Characterization and expression analysis of Lc-Sox4 in large yellow croaker Larimichthys crocea

The characterization and expression of Sox4 in large yellow croaker (Lc-Sox4) were studied in this paper. Lc-Sox4 contains a protein of 371 amino acids with a conserved high mobility group box. Quantitative real-time PCR displayed that the expression of Lc-Sox4 had tissue and gender specificity existing in brain, gonad, heart, intestine, and head kidney with male>female, in eye with female>male. During embryogenesis, Lc-Sox4 was expressed highest in one-day-post-hatching stage, next in formation-of-eye-lens stage. The expression pattern of Lc-Sox4 was different from that of Lc-Sox11a. The expression of Lc-Sox4 was significantly lower than that of Lc-Sox11a in the all tested tissues and embryonic stages except in heart, spleen, mutiple-cell, formation-of-eye-lens, and one-day-post-hatching stages (with Lc-Sox4 higher than Lc-Sox11a). There was overlapping expression between Lc-Sox4 and Lc-Sox11a in brain, gill, female eye, testis, formation-of-eye-lens stage and one-day post hatching stage. The whole mount in situ hybridization results indicated that Lc-Sox4 was expressed at all embryonic stages except 2-cell stage. The positive signals were mainly distributed in the central nervous system and notochord at one-day-post-hatching stage. In short, we first identified and analyzed the temporal and spatial expression patterns of Lc-Sox4 to elucidate its important influence on the development of nervous system, visual system and heart. We also detected the overlapping expression between Lc-Sox4 and Lc-Sox11a which may reveal the functional redundancy of them. These data would shed light on the molecular mechanism of development in large yellow croaker.

The Characterization of RHEB gene and its Responses to Hypoxia and Thermal Stresses in the Small Abalone Haliotis diversicolor

RHEB (Ras Homolog Enriched in Brain) is a GTP-binding protein that is ubiquitously expressed in humans and other mammals. The protein is largely involved in the mechanistic target of rapamycin (mTOR) pathway, and regulates the cell cycle progression and growth. The goal of this study was to characterize the RHEB gene in the small abalone Haliotis diversicolor, and identify the responses of RHEB gene to stresses of hypoxia or/and thermal. The objectives were to: 1) clone the full-length cDNA RHEB gene in the H. diversicolor (HdRHEB); 2) quantify the expression of HdRHEB gene in tissues of haemocytes, mantle, kidney, gill, digestive tract, colleterial gland, and hepatopancreas by using RT-PCR, and 3) evaluate the responses of HdRHEB in gill and haemocyte to stresses of hypoxia (0.2mg/l00ml), thermal (31°C), and combination of hypoxia (0.4mg/l00ml) and thermal (30°C) at exposure time of 0, 4, 24, 96, and 192h. The full length cDNA of HdRHEB was 1044bp encoding a peptide of 182 amino acid residues. Expression of HdRHEB gene was detected in all of the 7 tissues and showed the highest in mantle (P<0.05). Under hypoxia, expression of HdRHEB in gill increased significantly at 4h, 24h and 96h (P<0.05), and that in haemocyte increased significantly at 24h, 96h and 192h (P<0.05). Under thermal stress, expression of HdRHEB gene in gill decreased significantly at 4h and 24h, while expression in haemocyte decreased significantly all the time. Under thermal and hypoxia stresses, expression of HdRHEB gene in gill and haemocyte was up-regulated significantly at 24h and 96h (P<0.05). The results in this study demonstrated for the first time that RHEB gene in abalones is able to response to stress stimuli of hypoxia or/and thermal.

Identification and expression of transcription factor sox2 in large yellow croaker Larimichthys crocea

As an important transcription and pluripotency factor, Sox2 plays its functions essentially in the regulation of self-renewal and pluripotency of embryonic and neural stem cells, as well as embryogenesis, organogenesis, neurogenesis and regeneration. The data is lacking on Sox2 in large yellow croaker (Larimichthys crocea) (Lc-Sox2) which is a limitation on the generation of induced pluripotent stem cells (iPSCs). In this study, Lc-sox2 was cloned by RACE (rapid amplification of cDNA ends) and analyzed by Bioinformatics. The quantitative real-time PCR (qRT-PCR) and whole mount in situ hybridization (WISH) were used to detect the expression of Lc-sox2. The full-length cDNA sequence of Lc-sox2 is 2135 bp and encodes a 322-aa (amino acids). Lc-Sox2 possesses a highly conserved HMG-box as DNA-binding domain, maintains highly conserved with vertebrates, particularly with teleosts. In tissues, Lc-sox2 was expressed with gender difference in brain and eye (female > male), in embryos, Lc-sox2 was expressed with a zygotic type that the high level expression began to appear in the gastrula stage. The spatio-temporal expression patterns of Lc-sox2 suggested the potential involvement in embryogenesis, neurogenesis, gametogenesis and adult physiological processes of large yellow croaker. Our results contributed to better understanding of Sox2 from large yellow croaker.

Identification and comparative analysis of the ovary and testis microRNAome of mud crab Scylla paramamosain : JIA et al.

The role of microRNA (miRNA) in reproductive regulation is attracting increasingly more attention. In this study, we obtained 9,643,114 and 15,498,999 raw reads from the ovary and testis library of important farmed mud crab Scylla paramamosain, respectively. After data mining, a total of 4,096,464 and 11,737,973 mappable small RNA sequences remained for analysis. By mapping to the reference genome and expressed sequence tag (EST) of Daphnia pulex and other crabs, a total of 1,417 miRNAs were identified. On the basis of 1,417 miRNAs, 514 (36.3%) unique miRNAs coexpressed in the gonad of female and male libraries, and 336 (23.7%) and 567 (40%) expressed preferentially in female and male libraries, respectively. Analysis of library sequencing data resulted in the identification of 108 miRNAs (out of 1,417; 7.6%) that showed significant differential expression between the two samples. Of these, 13 miRNAs were expressed only in the testis, two miRNAs were expressed only in the ovary, and 93 miRNAs were coexpressed: 57 (61.3%) were upregulated (ovary/testis) and 36 (38.7%) were downregulated (ovary/testis). To confirm the expression patterns of the predicted miRNAs, we randomly selected 14 candidate miRNAs from 108 differentially expressed miRNAs and performed stem–loop real time quantitative PCR (RT‐qPCR) assays in five ovary developing stages. Five miRNAs showed similar expression patterns in almost every stage as those revealed by identification of differentially expressed genes (IDEG6) analysis. The above five miRNAs were predicted to match the 3′‐untranslated region of the published S. paramamosain gene. Four out of five miRNA had a regulation effect on many genes, especially the genes related to gonadal development.

miR-34 regulates reproduction by inhibiting the expression of MIH, CHH, EcR and FAMeT genes in mud crab Scylla paramamosain : ZHOU et al.

Mud crab Scylla paramamosain is a commercially important species widely cultured in China. It is well known that the eyestalk regulates reproductive activities in crustaceans. In our previous research, we found that the miR‐34 expression level in male eyestalk was significantly higher than that in females. Thus, we assumed that it may play an important role in regulating reproduction. In this study, we used bioinformatic tools to identify the target genes of miR‐34 in eyestalk. Six reproduction‐related genes with an intact 3′‐untranslated region (UTR), including molt‐inhibiting hormone (MIH), crustacean hyperglycemic hormone (CHH), vitellogenesis‐inhibiting hormone, red pigment concentrating hormone, ecdysone receptor (EcR), and farnesoic acid methyltransferase (FAMeT) were identified. When the 3′‐UTR plasmid vectors of the six genes were cotransfected with miR‐34 mimics into 293FT cells, respectively, the luciferase activities of four genes (MIH, CHH, EcR, and FAMeT) were significantly decreased compared with that in the control group; on the contrary, when the six plasmid vectors were cotransfected with the miR‐34 inhibitor respectively, the luciferase activities of four genes (MIH, CHH, EcR, and FAMeT) were significantly higher than that in the control group. When agomiR‐34 and antagomiR‐34 were injected into the eyestalk respectively in vivo, the expression levels of the MIH, CHH, EcR, and FAMeT genes were detected by a quantitative real‐time polymerase chain reaction. The results showed that agomiR‐34 suppressed the expression of the four genes, whereas antagomiR‐34 enhanced their expression. These experimental results confirmed our hypothesis that miR‐34 may indirectly regulate reproduction via binding to the 3′‐UTRs of MIH, CHH, EcR, and FAMeT genes and suppressing their expression.

Transcriptome Analysis Provides Insights into Differentially Expressed Genes and Long Non-Coding RNAs Involved in Sex-Related Differences in Amur sturgeon (Acipenser schrenckii): ZHANG et al.

In the present study, the next‐generation sequencing technology was used to develop a transcriptome database of gonad and liver from 3‐year‐old male and female Amur sturgeons (Acipenser schrenckii). A total of 139,406 unigenes were generated after the Illumina Hiseq. 2500 sequence and assembled by Trinity. The differential expression analysis between male and female obtained 5,199 differentially expressed genes (DEGs) in gonad and 457 DEGs in liver. Gene Ontology enrich analysis showed that the specific DEGs of gonad play a dominant role in reproductive processes. Although the specific DEGs of liver indicated their primary responsibility for energy metabolism, the DEGs of liver and gonad co‐own enriched in terms associated with reproduction suggested that liver also plays a role in sex‐related differences in Amur sturgeon. Furthermore, genes related to sex‐related differences were selected to validate among the four different tissues by real‐time quantitative polymerase chain reaction (qRT‐PCR). In addition, by trans‐acting analysis, a total of 5,206 putative long noncoding RNAs (lncRNAs) and 3,490 target genes of lncRNAs were predicted from gonad and liver. Moreover, several lncRNAs targeting Mea1, Piwil1, Tdrd1, Nanos2, Ankrd49, and ZP3 may have potential regulatory effect related to gametogenesis and gonadal differentiation were identified and validated by qRT‐PCR. These results suggested for the first time that lncRNAs might be one of the effect factors in regulating the differential expression of messenger RNAs associated with sex‐related differences in Amur sturgeon.

Nanos 3 not nanos 1 and nanos 2 is a germ cell marker gene in large yellow croaker during embryogenesis

In this study, three nanos gene subtypes (Lcnanos1, Lcnanos2 and Lcnanos3) from Larimichthys crocea, were cloned and characterized. We determined the spatio-temporal expression patterns of each subtype in tissues as well as the cellular localization of mRNA in embryos. Results showed that deduced Nanos proteins have two main homology domains: N-terminal CCR4/NOT1 deadenylase interaction domain and highly conserved carboxy-terminal region bearing two conserved CCHC zinc-finger motifs. The expression levels of Lcnanos1 in testis were significantly higher than other tissues, followed by heart, brain, eye, and ovary. Nevertheless, both Lcnanos2 and Lcnanos3 were restrictedly expressed in testis and ovary, respectively. No signals of Lcnanos1 and Lcnanos2 expression were detected at any developmental stages during embryogenesis. On the contrary, the signals of Lcnanos3 were detected in all stages examined. Lcnanos3 transcripts were firstly localized to the distal end of cleavage furrow at the 2-cell stage. Subsequently, mounting positive signals started to appear in a small number of cells as the embryo developed to blastula stage and early-gastrula stage. As development proceeded, positive signals were found in the primitive gonadal ridge. These cells of Lcnanos3 positive signals implied the specification of the future PGCs at this stage. It also suggested that PGCs of croaker originate from four clusters of cells which inherit maternal germ plasm at blastula stage. Furthermore, we preliminarily analyzed the migration route of PGCs in embryos of L. crocea. In short, this study laid the foundation for studies on specification and development of germ cell from L. crocea during embryogenesis.