Whole-Transcriptome Sequencing-Based Analysis of DAZL and Its Interacting Genes during Germ Cells Specification and Zygotic Genome Activation in Chickens.

Sohyoung Won,Jae Yong Han,Heebal Kim,Dongahn Yoo,Jong Won Han,Deivendran Rengaraj

doi:10.3390/ijms21218170

Abstract

The deleted in azoospermia like (DAZL) is required for germ cells development and maintenance. In chickens, the mRNA and protein of DAZL, a representative maternally inherited germ plasm factor, are detected in the germ plasm of oocyte, zygote, and all stages of the intrauterine embryos. However, it is still insufficient to explain the origin and specification process of chicken germ cells, because the stage at which the zygotic transcription of DAZL occurs and the stage at which the maternal DAZL RNA/protein clears have not yet been fully identified. Moreover, a comprehensive understanding of the expression of DAZL interacting genes during the germ cells specification and development and zygotic genome activation (ZGA) is lacking in chickens. In this study, we identified a set of DAZL interacting genes in chickens using in silico prediction method. Then, we analyzed the whole-transcriptome sequencing (WTS)-based expression of DAZL and its interacting genes in the chicken oocyte, zygote, and Eyal-Giladi and Kochav (EGK) stage embryos (EGK.I to EGK.X). In the results, DAZL transcripts are increased in the zygote (onset of transcription), maintained the increased level until EGK.VI, and decreased from EGK.VIII (possible clearance of maternal RNAs). Among the DAZL interacting genes, most of them are increased either at 1st ZGA or 2nd ZGA, indicating their involvement in germ cells specification and development.

Highlights

During fertilization, the haploid egg nucleus fuses with the sperm nucleus to produce a diploid one-cell embryo
The deleted in azoospermia like (DAZL), an RNA-binding protein, has been identified in diverse vertebrate and invertebrate species, including chickens, as a master factor for the germ cells development and maintenance [8,9]
To uncover the above themes, we identified a set of DAZL interacting genes in chickens using in silico prediction method

Summary

Introduction

The haploid egg (oocyte) nucleus fuses with the sperm nucleus to produce a diploid one-cell embryo (zygote). The preformation mode has been well explained or predicted in species, such as fruit flies, frogs, zebrafish, roundworm, sturgeon, and ascidians [2,4]. Frogs, and zebrafish, the maternally stored germ plasm (containing RNAs, proteins, and energy-rich mitochondria) in the oocyte is inherited into the cells specifying precursor germ cells during early embryonic development [5,6,7]. In both modes, germ cells specification requires the expression of germ plasm factors and the precise interaction of germ cells-related genes

Methods

Results

Conclusion