Genome-wide identification of 99 autophagy-related (Atg) genes in the monogonont rotifer Brachionus spp. and transcriptional modulation in response to cadmium

Autophagy originated from the common ancestor of all life forms, and its function is highly conserved from yeast to humans. Autophagy plays a key role in various fundamental biological processes including defense, and has developed through serial interactions of multiple gene sets referred to as autophagy-related (Atg) genes. Despite their significance in metazoan life and evolution, few studies have been conducted to identify these genes in aquatic invertebrates. In this study, we identified whole Atg genes in four Brachionus rotifer spp., namely B. calyciflorus, B. koreanus, B. plicatilis, and B. rotundiformis, through searches of their entire genomes; and we annotated them according to the yeast nomenclature. Twenty-four genes orthologous to yeast genes were present in all of the Brachionus spp. while three additional gene duplicates were identified in the genome of B. koreanus, indicating that these genes had diversified during the speciation. Also, their transcriptional responses to cadmium exposure indicated regulation by cadmium-induced oxidative-stress-related signaling pathways. This study provides valuable information on 99 conserved Atg genes involved in autophagosome formation in Brachionus spp., with transcriptional modulation in response to cadmium, in the context of the role of autophagy in the damage response.