The insect SNMP gene family

Area of Science:

• Evolutionary biology
• Molecular biology
• Insect genetics

Background:

• Odorant receptors in insects are crucial for detecting environmental cues like pheromones.
• SNMPs (Sensory neuron membrane proteins) are insect gene clades related to the human CD36 transporter and associate with chemosensory neurons.
• Previous work suggested a complex SNMP clade structure within insects.

Purpose of the Study:

• To resolve the evolutionary relationships within the insect SNMP gene clade.
• To identify orthologous SNMP genes across diverse insect orders.
• To investigate potential functional expansions of SNMP genes in specific insect lineages.

Main Methods:

• Comparative sequence analysis of SNMP1 and SNMP2 genes using cDNA and genomic data.
• Phylogenetic analysis to resolve the SNMP clade structure.
• Evolutionary selection analysis (dN/dS ratios) to infer functional expression of dipteran SNMPs.

Main Results:

• Identified two well-supported SNMP sub-clades, SNMP1 and SNMP2, conserved across Diptera and Lepidoptera, and likely Holometabola.
• Corrected orthologous sequences in several insect genomes.
• Provided evidence for functional expression of dipteran SNMPs.
• Observed expansions of the SNMP1 sub-clade in Culex pipiens quinquefasciatus and Tribolium castaneum.

Conclusions:

• The insect SNMP gene family is structured into two major clades, SNMP1 and SNMP2, with deep evolutionary roots.
• SNMP1 may possess an expanded functional repertoire in certain insect species, potentially related to chemosensation.
• Further research into SNMP function in specific insect groups is warranted.