Transcriptome Analysis of Ovary Development in Nile Tilapia Under Different Photoperiod Regimes.

Zhanyang Tang,Yongju Luo,Weiwei Miao,Xu Zhang,Lei Zhou,Zhongbao Guo,Jun Xiao,Huan Zhong,Yi Zhou

doi:10.3389/fgene.2019.00894

Zhanyang Tang, Yongju Luo + Show 7 more

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https://doi.org/10.3389/fgene.2019.00894

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Abstract

This study investigated the molecular mechanisms involved in ovarian transcriptomic responses in Nile tilapia under different photoperiod regimes. Histological analysis indicated that ovarian development was significantly affected by photoperiod. The photoperiods tested were as follows: LD (12 h light:12 h dark), LL (24 h light:0 h dark), and DD (0 h light:24 h dark). The longer photoperiod (LL) was shown to induce ovary development earlier than LD and DD. Next, ovary transcriptome levels were sequenced and analyzed. These data indicated that 988, 992, and 1,036 differentially expressed genes (DEGs) were detected by comparing LD–LL, LD–DD, and LL–DD. A number of genes that may be involved in photoperiod-specific regulation of ovarian development were observed. These findings may be useful for investigating the molecular mechanisms underlying light-induced ovarian development in Nile tilapia.

Highlights

Nile tilapia is one of the most important commercial fish worldwide and is prized as an aquaculture species (Biswas et al, 2005; Fernandes et al, 2015)
After filtering low-quality reads from the raw reads, 44,932,587 clean reads (LD), 23,635,959 clean reads (LL), and 22,735,011 clean reads (DD) were obtained
The results showed that the percentage of mapped reads to reference genomes was 75.94, 75.18, and 77.70% in light:12 h dark (LD), LL, and DD RNA samples, respectively

Summary

Introduction

Nile tilapia is one of the most important commercial fish worldwide and is prized as an aquaculture species (Biswas et al, 2005; Fernandes et al, 2015). Ovary development is crucial in producing sexually mature females for fish reproduction. It has been established in the literature that light regulates ovary development via the brain–pituitary–gonad (BPG) axis. In the case of tilapia and other tropical fish species (Yumnamcha et al, 2017; Khan et al, 2018), manipulating the photoperiod, including varying the light intensity, can have a positive effection reproduction. Ridha et al (1998) reported that longer and brighter days (18 days) resulted in more fry and improved spawning synchrony in Nile tilapia compared with shorter days and lower light intensity. Campos-Mendoza (Campos-Mendoza et al, 2004) showed that longer day lengths help to alleviate

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