Gonad-Specific Transcriptomes Reveal Differential Expression of Gene and miRNA Between Male and Female of the Discus Fish (Symphysodon aequifasciatus)

Abstract

The discus fish (Symphysodon aequifasciatus) is an ornamental fish that is well-known around the world. In artificial reproduction, they must be matched by one male and one female, whereas phenotype investigation indicated that there are no significant differences in appearance between males and females, which causes great difficulties in the mating during artificial reproduction. So, it is of great importance to establish artificial sex identification methods for the discus fish. The molecular mechanism of the sexual dimorphism of the discus fish was previously unknown. In this study, we constructed six cDNA libraries from three adult testes and three adult ovaries and performed RNA sequencing for identifying sex-biased candidate genes and microRNAs (miRNAs). A total of 50,082 non-redundant genes (unigenes) were identified, of which 18,570 unigenes were significantly overexpressed in testes, and 11,182 unigenes were significantly overexpressed in ovaries. A total of 551 miRNAs were identified, of which 47 miRNAs were differentially expressed between testes and ovaries. Eight differentially expressed unigenes, seven differentially expressed miRNAs and one non-differential miRNA were validated by quantitative real-time polymerase chain reaction. Twenty-four of these differentially expressed miRNAs and their 15 predicted target genes constituted 41 miRNA-mRNA interaction pairs, and some of vital sex-related metabolic pathways were also identified. These results revealed these differentially expressed genes and miRNAs between ovary and testis might be involved in regulating gonadal development, sex determination, gametogenesis, and physiological function maintenance, and there are complex regulatory networks between genes and miRNAs. It can help us understand the molecular mechanism of the sexual dimorphism and obtain a high-efficiency sex identification method in the artificial reproduction process of the discus fish.

Identification and characterization of a new species of Taxus — Taxus qinlingensis by multiple taxonomic methods

“…Up to now, the sex transformation mechanisms of Taxus remain largely unknown [ 47 , 48 ]. Generally speaking, the mechanisms of sex determination systems including genetic sex determination (GSD), environment sex determination (ESD), and the combination of GSD and ESD [ 49 ]. These mechanisms reveals that plants have to adopt different strategies to cope with diverse biotic and abiotic stresses for survival in adverse environmental conditions [ 50 , 51 ].…”

Comparative gonad transcriptome analysis in cobia (Rachycentron canadum)

“…Gonads are indispensable reproductive organs, and their development is commonly controlled by multiple sex-associated genes and pathways. With the rapid development of sequencing technology, RNA sequencing (RNA-Seq) of gonadal samples has been used to examine sex determination or differentiation in various fish species ( Lin et al, 2017 ; Fu et al, 2020 ; Li et al, 2020 ; Chen et al, 2021 ; Lin et al, 2021 ; Gao et al, 2022 ). The transcriptomic information available in cobia is currently limited.…”

Integrated mRNA and miRNA Expression Profile Analysis of Female and Male Gonads in Acrossocheilus fasciatus

“…MicroRNAs (miRNAs) belong to small noncoding RNAs that are approximately 21 nucleotides in length and modulate gene expression post-transcriptionally [ 1 ]. As the universal specificity factors, miRNAs involve various biological processes through complete or partial complementary manner binding to the 3′ untranslated region of target genes to mediate gene silence [ 2 ]. To achieve these functions, miRNAs along with Argonaute proteins form the RNA-induced silencing complex (RISC) to repress target genes’ expression through mRNA cleavage, degradation, and/or translational repression [ 3 ].…”