Genome polyploidy has been revealed to result in evolutionary advantages and novelties, and therefore, polyploid aquatic animals may possess excellent traits of economic interest including rapid ...growth, extensive adaptability and disease resistance. For this reason, numerous species of natural polyploid fishes, such as common carp, gibel carp, crucian carp, salmon, and sturgeon, were chosen as important target species for aquaculture. Many artificial polyploids have been commercially utilized for aquaculture and most of them were created from natural polyploid fishes of the Cyprinidae and Salmonidae. Thanks to the easy mass production and better economic traits in growth and flesh quality, the synthetized autopolyploids or allopolyploids from natural polyploid species in cyprinid fishes have been extensively applied to aquaculture throughout China. This review outlines polyploidy advantages and innovative opportunities, lists natural polyploid species used in aquaculture, and summarizes artificial polyploids that have been induced or synthetized, and used in aquaculture. Moreover, some main research trends on polyploid utilization and ploidy manipulation of aquaculture animals are also introduced and discussed in the review.
A unisexual species is generally associated with polyploidy, and reproduced by a unisexual reproduction mode, such as gynogenesis, hybridogenesis or parthenogenesis. Compared with other unisexual and ...polyploid species, gibel carp (Carassius auratus gibelio) has a higher ploidy level of hexaploid. It has undergone several successive rounds of genome polyploidy, and experienced an additional, more recent genome duplication event. More significantly, the dual reproduction modes, including gynogenesis and sexual reproduction, have been demonstrated to coexist in the polyploid gibel carp. This article reviews the genetic basis concerning polyploidy origin, clonal diversity and dual reproduction modes, and outlines the progress in new variety breeding and gene identification involved in the reproduction and early development. The data suggests that gibel carp are under an evolutionary trajectory of diploidization. As a novel evolutionary developmental (Evo-Devo) biology model, this work highlights future perspectives about the functional divergence of duplicated genes and the sexual origin of vertebrate animals.
The spinyhead croaker (Collichthys lucidus) is a commercially important fish species, which is mainly distributed in the coastal regions of China. However, little is known about the molecular ...regulatory mechanism underlying reproduction in C. lucidus. A de novo transcriptome assembly in brain, liver, ovary and testis tissues of C. lucidus was performed. Illumina sequencing generated 60,322,004, 57,044,284, 60,867,978 and 57,087,688 clean reads from brain, liver, ovary and testis tissues of C. lucidus, respectively. Totally, 131,168 unigenes with an average length of 644 bp and an N50 value of 1033 bp were assembled. In addition, 1288 genes were differentially expressed between ovary and testis, including 442 up-regulated and 846 down-regulated in ovary. Functional analysis revealed that the differentially expressed genes between ovary and testis were mainly involved in the function of sexual reproduction, sex differentiation, development of primary male sexual characteristics, female gamete generation, and male sex differentiation. A number of genes which might be involved in the regulation of reproduction and sex determination were found, including HYAL and SYCP3 and BMP15. Furthermore, 35,476 simple sequence repeats (SSRs) were identified in this transcriptome dataset, which would contribute to further genetic and mechanism researches. De novo transcriptome sequencing analysis of four organs of C. lucidus provides rich resources for understanding the mechanism of reproductive development of C. lucidus and further investigation of the molecular regulation of sex determination and reproduction of C. lucidus.
The regulatory mechanism of gonadal sex differentiation, which is complex and regulated by multiple factors, remains poorly understood in teleosts. Recently, we have shown that compromised androgen ...and estrogen synthesis with increased progestin leads to all-male differentiation with proper testis development and spermatogenesis in cytochrome P450 17a1 (cyp17a1)-/- zebrafish. In the present study, the phenotypes of female-biased sex ratio were positively correlated with higher Fanconi anemia complementation group L (fancl) expression in the gonads of doublesex and mab-3 related transcription factor 1 (dmrt1)-/- and cyp17a1-/-;dmrt1-/- fish. The additional depletion of fancl in cyp17a1-/-;dmrt1-/- zebrafish reversed the gonadal sex differentiation from all-ovary to all-testis (in cyp17a1-/-;dmrt1-/-;fancl-/- fish). Luciferase assay revealed a synergistic inhibitory effect of Dmrt1 and androgen signaling on fancl transcription. Furthermore, an interaction between Fancl and the apoptotic factor Tumour protein p53 (Tp53) was found in vitro. The interaction between Fancl and Tp53 was observed via the WD repeat domain (WDR) and C-terminal domain (CTD) of Fancl and the DNA binding domain (DBD) of Tp53, leading to the K48-linked polyubiquitination degradation of Tp53 activated by the ubiquitin ligase, Fancl. Our results show that testis fate in cyp17a1-/- fish is determined by Dmrt1, which is thought to stabilize Tp53 by inhibiting fancl transcription during the critical stage of sexual fate determination in zebrafish.
The androgen receptor (AR) is a nuclear receptor protein family member and inducible transcription factor that modulates androgen target gene expression. Studies using a mouse model confirmed the ...need for
in reproductive development, particularly spermatogenesis. Here, we investigated the role of
in zebrafish using CRISPR/Cas9 gene targeting technology. Targeted disruption of
in zebrafish increases the number of female offspring and increases offspring weight. In addition,
-null male zebrafish have female secondary sex characteristics. More importantly, targeted disruption of
in zebrafish causes male infertility via defective spermatogenesis and female premature ovarian failure during growth. Mechanistic assays suggest that these effects are caused by fewer proliferated cells and more apoptotic cells in
-null testes. Moreover, genes involved in reproductive development, estradiol induction and hormone synthesis were dys-regulated in testes and ovaries and the reproductive-endocrine axis was disordered. Our data thus suggest that the zebrafish
is required for spermatogenesis and maintenance of ovarian function, which confirms evolutionarily conserved functions of
in vertebrates, as well as indicates that
-null zebrafish are a suitable model for studying pathologic mechanisms related to androgen disorders.
Genome duplication supplies raw genetic materials and has been thought to be essential for evolutionary innovation and ecological adaptation. Here, we select
(
) genes to study the evolution of the ...duplicated genes in the polyploid
complex, including amphidiploid
and amphitriploid
. Phylogenetic, chromosomal location and read coverage analyses indicate that most of
genes exhibit a 2:1 relationship with zebrafish orthologs and confirm two rounds of polyploidy, an allotetraploidy followed by an autotriploidy, occurred during
evolution. The lineage-specific expansion and biased retention/loss of
genes are also found in
. Transcriptome analyses across eight adult tissues and seven embryogenesis stages reveal varied expression dominance and divergence between the two species. The expression of
in response to
herpesvirus 2 infection shows different expression changes corresponding to distinct herpesvirus resistances in three
gynogenetic clones. Finally, we find that most
genes possess three alleles except eight genes that have lost one or two alleles due to genome rearrangement. The allele expression bias is prosperous for
genes and varies during embryogenesis owning to the sequential expression manner of the alleles. The current study provides global insights into the genomic and transcriptional evolution of duplicated genes in a given superfamily resulting from multiple rounds of polyploidization.
Long noncoding RNAs (lncRNAs) are regulatory transcripts in various biological processes. However, the role of lncRNAs in germline development remains poorly understood, especially for fish ...primordial germ cell (PGC) development. In this study, the lncRNA profile of zebrafish PGC was revealed by single cell RNA-sequencing and bioinformatic prediction. We established the regulation network of lncRNA-mRNA associated with PGC development, from which we identified three novel lncRNAs-
,
, and
-highly expressing in PGCs and gonads. Fluorescent in situ hybridization indicated germline-specific localization of
and
in the cytoplasm and nucleus of spermatogonia, spermatocyte, and occyte, and they were co-localized with vasa in the cytoplasm of the spermatogonia. By contrast,
was localized in the cytoplasm of male germline, myoid cells and ovarian somatic cells. Loss- and gain-of-function experiments demonstrated that knockdown and PGC-specific overexpression of
as well as universal overexpression of
significantly disrupted PGC development. In summary, the present study revealed the lncRNA profile of zebrafish PGC and identified two novel lncRNAs associated with PGC development, providing new insights for understanding the regulatory mechanism of PGC development.
T helper 17 (Th17) cells specifically transcribe the Il17 and Il17f genes, which are localized in the same chromosome region, but the underlying mechanism is unclear. Here, we report a cis element ...that we previously named conserved noncoding sequence 2 (CNS2) physically interacted with both Il17 and Il17f gene promoters and was sufficient for regulating their selective transcription in Th17 cells. Targeted deletion of CNS2 resulted in impaired retinoic acid-related orphan receptor gammat (RORγt)-driven IL-17 expression in vitro. CNS2-deficient T cells also produced substantially decreased amounts of IL-17F. These cytokine defects were associated with defective chromatin remodeling in the Il17-Il17f gene locus, possibly because of effects on CNS2-mediated recruitment of histone-modifying enzymes p300 and JmjC domain-containing protein 3 (JMJD3). CNS2-deficient animals were also shown to be resistant to experimental autoimmune encephalomyelitis (EAE). Our results thus suggest that CNS2 is sufficient and necessary for Il17 and optimal Il17f gene transcription in Th17 cells.
► CNS2 is sufficient to drive expression of both IL-17 and IL-17F in Th17 cells ► CNS2 is indispensible for lineage-specific expression of IL-17 ► CNS2 interacts with the Il17 and Il17f promoters in a cell-type-specific manner ► CNS2 modulates the chromatin accessibility of the Th17 cytokine gene locus
Improvement in fish feed conversion efficiency (FCE) is beneficial for sustaining global food fish supplies. Here, we show that a set of polymorphisms at locus of the corticotropin releasing hormone ...receptor 2 (crhr2), which is involved in hypothalamus-pituitary-interrenal (HPI) axis signaling, is associated with improved FCE in farmed allogynogenetic gibel carp strain CAS III compared with that in the wild gibel carp strain Dongting (DT). This set of polymorphisms downregulates the expression levels of crhr2 mRNA in the brain and pituitary tissues in gibel carp strain CAS III compared with those in strain DT. Furthermore, compromised HPI axis signaling is observed in gibel carp strain CAS III, such as decreased α-melanocyte stimulating hormone protein levels, plasma cortisol content, and stress responses. Moreover, enhanced activation of protein kinase B/mammalian target of rapamycin complex 1 signaling observed in the muscle tissue of strain CAS III in comparison to that in strain DT indicated elevated anabolic metabolism in strain CAS III. Thus, these studies demonstrate that the genetic markers associated with compromised HPI axis signaling, such as crhr2, are potentially useful for genetic selection toward improvement in farmed fish growth and FCE, which would reduce fishmeal consumption and thereby indirectly facilitate sustainable fisheries.
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