A Family of Genes Clustered at the Triplo-lethal Locus of Drosophila melanogaster Has an Unusual Evolutionary History and Significant Synteny With Anopheles gambiae

Abstract

Within the unique Triplo-lethal region (Tpl) of the Drosophila melanogaster genome we have found a cluster of 20 genes encoding a novel family of proteins. This family is also present in the Anopheles gambiae genome and displays remarkable synteny and sequence conservation with the Drosophila cluster. The family is also present in the sequenced genome of D. pseudoobscura, and homologs have been found in Aedes aegypti mosquitoes and in four other insect orders, but it is not present in the sequenced genome of any noninsect species. Phylogenetic analysis suggests that the cluster evolved prior to the divergence of Drosophila and Anopheles (250 MYA) and has been highly conserved since. The ratio of synonymous to nonsynonymous substitutions and the high codon bias suggest that there has been selection on this family both for expression level and function. We hypothesize that this gene family is Tpl, name it the Osiris family, and consider possible functions. We also predict that this family of proteins, due to the unique dosage sensitivity and the lack of homologs in noninsect species, would be a good target for genetic engineering or novel insecticides.

A chromosome-level genome assembly of the orange wheat blossom midge,Sitodiplosis mosellanaGéhin (Diptera: Cecidomyiidae) provides insights into the evolution of a detoxification system

“…Gene families were commonly found in genomes and were thought to evolve by gene duplication and neofunctionalization. The Osiris gene family was a large conserved family first described in D. melanogaster ( Dorer et al 2003 ). Twenty-three Osiris genes were originally found in the D. melanogaster genome, with 20 of them located on chromosome 3R in a cluster.…”

“…Twenty-three Osiris genes were originally found in the D. melanogaster genome, with 20 of them located on chromosome 3R in a cluster. The Osiris gene family was also present in the mosquito A. gambia genome ( Dorer et al 2003 ) and S. mosellana genome. The families maintained a remarkable degree of synteny displays remarkable synteny and sequence conservation with the Drosophila cluster ( Shah et al 2012 ).…”

Comparative transcriptomics of the Drosophila olfactory subsystems identifies a support cell-expressed Osiris protein required for pheromone sensing

“…We subsequently focused on characterizing the Or subsystem gene Osi8 , a member of a family of 24 Osi genes that each encode an N-terminal signal peptide, a domain of unknown function (DUF1676), followed by a presumed transmembrane domain (Figure 3A). This family appears to be largely insect-specific, with syntenically-arranged orthologs of most family members present in diverse insect orders and, with rare exceptions (Smith et al, 2018), no related genes in the genomes of non-insect Arthropoda or other invertebrates (Dorer et al, 2003; Shah et al, 2012; Smith et al, 2018). Notably, of the analyzed insect species, Osi8 is absent in only the human body louse Pediculus humanus (Shah et al, 2012), which also has a greatly reduced Or repertoire compared to many other insects (Kirkness et al, 2010).…”

Abnormal Antennal Olfactory Sensilla Phenotypes Involved in Olfactory Deficit in Bactrocera correcta (Diptera: Tephritidae)

“…Osiris gene families found in a number of insect genomes are highly conserved among insects [ 32 , 33 , 34 ]. Furthermore, Osiris genes are expressed mainly in cuticle-secreting epidermal cells at cuticle-secretion stages [ 12 , 34 ].…”