Phylogenetic analysis and classification of insect achaete-scute complex genes

Abstract

Abstract Achaete-scute complex (ASC) genes play essential roles in neurogenesis of eukaryotes. Insect ASC genes are currently grouped into two distinct families, ASCa and ASCb. However, the identified insect ASCb family genes are not orthologous to known ASCb family genes from other animals such as nematode and mammal. Besides, many ASC genes have been annotated differently in GenBank. In this study, ASC genes from 41 insect species were obtained in silico and analyzed to clarify their evolutionary relationships with known ASC genes from other animals. Based on our analyses, a new naming system is suggested for classification of ASC genes. Firstly, a new family (ASCc) is added into the already existing two families and the gene of this family is named Asl (Achaete-scute-like). Secondly, Ash4, Ash5 and Ash6 are used to name insect ASC genes that are not orthologous to ac, sc, l'sc and ase genes of Drosophila melanogaster and Ash1 to Ash3 genes of Bombyx mori. This naming system can be used to correct inappropriate annotations of insect ASC genes in GenBank and to classify newly identified insect ASC genes. Additionally, a vast difference was found in ASC gene composition among various insect species, suggesting that different insect species might have originated from various ancestral lineages.