Label-free based quantitative proteomic analysis identifies proteins involved in the testis maturation of Bactrocera dorsalis (Hendel).

Complex structural and biochemical processes take place in insect testis maturation, but the mechanisms by which functional proteins induce and regulate male fertility are unknown. Proteomics has been widely used to identify functional proteins involved in such complex physiological processes. In this study, we performed a label-free based quantitative proteomic analysis of developing testis of Bactrocera dorsalis with the aim of shedding light on spermatogenesis, sperm formation and also tissue development. A total of 1912 reliable proteins were identified, including 1589, 1705 and 1723 proteins in 1-, 5- and 9-d-old testis, respectively. Most of these proteins (76.68%) were identified by two to ten peptides, and the mean number of peptides was 7.46 with an average sequence coverage of 30.71%. Quantitative proteomic analysis showed that there were 141 and 111 proteins which were abundant in the 5- and 9-d-old testis, respectively. The Gene Ontology (GO) and Clusters of Orthologous Groups (COG) analyses showed that many of these proteins function in cellular and metabolic processes, including binding and catalytic activities in molecular function analysis, and energy production, cell division, and cell motility in COG analysis. Potential functional proteins, such as heat shock proteins, glutathione S-transferase, transferrin, metalloproteinase and energy metabolism-related proteins, were found to be abundant in the intermediate and sexual maturity stages of testis. The findings in this study help us to better understand the molecular mechanisms behind testis development and spermatogenesis, which is essential for manipulating male fertility for ecological regulation and potential control of this species.