Transcriptome profiling reveals gene regulation programs underlying tail development in the Ornamented Pygmy frog Microhyla fissipes.

Shouhong Wang ,Yun‐Bo Shi ,Lusha Liu ,Jianping Jiang

doi:10.52586/5004

Abstract

Introduction: Tadpole tail develops from the tailbud, an apparently homogenous mass of cells at the posterior of the embryo. While much progress has been made in understanding the origin and the induction of the tailbud, the subsequent outgrowth and differentiation have received much less attention, particularly with regard to global gene expression changes. Methods: By using RNA-seq with SMRT and further analyses, we report the transcriptome profiles at four key stages of tail development, from a small tailbud to the onset of feeding (S18, S19, S21 and S28) in Microhyla fissipes, an anuran with a number of advantages for developmental and genetic studies. Results: We obtained 48,826 transcripts and discovered 8807 differentially expressed transcripts (DETs, q < 0.05) among these four developmental stages. We functionally classified these DETs by using GO and KEGG analyses and revealed 110 significantly enriched GO categories and 6 highly enriched KEGG pathways (Protein digestion and absorption; ECM-receptor interaction; Pyruvate metabolism; Fatty acid degradation; Valine, leucine and isoleucine degradation; and Glyoxylate and dicarboxylate metabolism) that are likely critically involved in developmental changes in the tail. In addition, analyses of DETs between any two individual stages demonstrated the involvement of distinct biological pathways/GO terms at different stages of tail development. Furthermore, the most dramatic changes in gene expression profile are those between S28 and any of the other three stages. The upregulated DETs at S28 are highly enriched in "myosin complex" and "potassium channel activity", which are important for muscle contraction, a critical function of the tail that the animal needs by the end of embryogenesis. Additionally, many DETs and enriched pathways discovered here during tail development, such as HDAC1, Hes1 and Hippo signaling pathway, have also been reported to be vital for the tissue/organ regeneration, suggesting conserved functions between development and regeneration. Conclusion: The present staudy provides a golbal overview of gene expression patterns and new insights into the mechanism involved in anuran tail development and regeneration.

Highlights

The tadpole tail is a larva-specific organ, which is twice as long as the body
Our results provide a global overview of gene expression patterns and new insights into the possible mechanism involved in tail development of frogs
Tailbud determination from stage 18 (S18) to S19 is defined by tailbud elongation while tailbud outgrowth refers to stages from S19 to S28, when a functional tail is formed [5]

Summary

Introduction

The tadpole tail is a larva-specific organ, which is twice as long as the body. It forms at the early embryonic stages and is lost at the climax of metamorphosis in anurans [1, 2]. The tail is anatomically defined by its position from posterior to the anal opening, a continuation of the structures of the main body axis, which is well patterned and contains many axial and paraxial tissues, including epidermis, connective tissue (dermis), spinal cord, notochord, dorsal aorta, and skeletal muscle [3, 4]. It has a number of functions at larval stages, such as swimming, balance, fat storage, and predator escape via autotomy [3]. No studies have employed systematic, high-throughput sequencing technologies, such as RNA-Seq and single molecule long-read sequencing (SMRT sequencing), for global analyses of gene expression changes and tail development

Methods

Results

Discussion

Conclusion