Integrated Analysis of mRNA- and miRNA-Seq in the Ovary of Rare Minnow Gobiocypris rarus in Response to 17α-Methyltestosterone.

Shaozhen Liu,Weiwei Wang,Yue Chen,Qing Liu,Qiong Yang,Wenzhong Liu,Jing Song,Yao Zheng

doi:10.3389/fgene.2021.695699

Shaozhen Liu, Weiwei Wang + Show 6 more

Open Access

https://doi.org/10.3389/fgene.2021.695699

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Abstract

17α-Methyltestosterone (MT) is a synthetic androgen. The objective of this study was to explore the effects of exogenous MT on the growth and gonadal development of female rare minnow Gobiocypris rarus. Female G. rarus groups were exposed to 25–100 ng/L of MT for 7 days. After exposure for 7 days, the total weight and body length were significantly decreased in the 50-ng/L MT groups. The major oocytes in the ovaries of the control group were vitellogenic oocytes (Voc) and cortical alveolus stage oocytes (Coc). In the MT exposure groups, some fish had mature ovaries with a relatively lower proportion of mature oocytes, and the diameter of the perinucleolar oocytes (Poc) was decreased compared with those of the control group. Ovarian VTG, FSH, LH, 11-KT, E2, and T were significantly increased after exposure to 50 ng/L of MT for 7 days. Unigenes (73,449), 24 known mature microRNAs (miRNAs), and 897 novel miRNAs in the gonads of G. rarus were found using high-throughput sequencing. Six mature miRNAs (miR-19, miR-183, miR-203, miR-204, miR-205, and miR-96) as well as six differentially expressed genes (fabp3, mfap4, abca1, foxo3, tgfb1, and zfp36l1) that may be associated with ovarian development and innate immune response were assayed using qPCR. Furthermore, the miR-183 cluster and miR-203 were differentially expressed in MT-exposed ovaries of the different G. rarus groups. This study provides some information about the role of miRNA–mRNA pairs in the regulation of ovarian development and innate immune system, which will facilitate future studies of the miRNA–RNA-associated regulation of teleost reproduction.

Highlights

17α-Methyltestosterone (MT) is a synthetic organic compound, which is a typical endocrine disruptor widely available in the environment
We found the decreasing vitellogenic oocytes (Voc) numbers in ovaries, indicating that MT could inhibit the gonadal development of female fish when exposed for 7 days
follicle-stimulating hormone (FSH), luteinizing hormone (LH), 11-KT, and T were significantly decreased in female fish after MT exposure to 25 ng/L for 7 days. 11-KT plays an important role in controlling pre-Voc growth in A. japonica (Lai et al, 2018)

Summary

Introduction

17α-Methyltestosterone (MT) is a synthetic organic compound, which is a typical endocrine disruptor widely available in the environment. Atrazine can upregulate aromatase expression through miRNAs, which supports the hypothesis that atrazine has endocrine-disrupting activity by altering the gene expression profile of the HPG axis through its corresponding miRNAs (Wang G. et al, 2019) Some proteins, such as β-catenin in freshwater mussel Hyriopsis cumingii (Wang F. et al, 2019) and vitellogenin (VTG) in Nothobranchius guentheri (Liu et al, 2017), may participate in a variety of physiological activities like immune regulation and sex determination. The changes in vtg expression are more intuitive to manifest that these genes can affect ovarian development through the regulation of miRNAs. In this study, we tested the sex hormone (E2, T, FSH, LH, and 11-KT) and VTG of G. rarus exposed to MT (25, 50, and 100 ng/L) for 7 days. We will further study miRNA–mRNA interaction networks, which may help explore the underlying mechanisms of the reproduction and immune system of G. rarus

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