Evolutionary genomics analysis reveals gene expansion and functional diversity of arylalkylamine N-acetyltransferases in the Culicinae subfamily of mosquitoes

Arylalkylamine N-acetyltransferase(aaNAT),considered a potential new insecticide target,catalyzes the acetylation of arylalkylamine substrates such as serotonin and dopamine and,hence,mediates diverse functions in insects.However,the origin of insect aaNATs(iaaNATs)and the evolutionary process that generates multiple aaNATs in mosquitoes remain largely unknown.Here,we have analyzed the genomes of 33 species to explore and expand our understanding of the molecular evolution of this gene family in detail.We show that aaNAT orthologs are present in Bacteria,Cephalochordata,Chondrichthyes,Cnidaria,Crustacea,Mammalia,Placozoa,and Teleoste,as well as those from a number of insects,but are absent in some species of Annelida,Echinozoa,and Mollusca as well as Arachnida.Particularly,more than 10 aaNATs were detected in the Culicinae subfamily of mosquitoes.Molecular evolutionary analysis of aaNAT/aaNAT-like genes in mosquitoes reveals that tandem duplication events led to gene expansion in the Culicinae subfamily of mosquitoes more than 190 million years ago.Further selection analysis demonstrates that mosquito aaNATs evolved under strongly positive pressures that generated functional diversity following gene duplication events.Overall,this study may provide novel insights into the molecular evolution of the aaNAT family in mosquitoes.

Crystal structure of acetylcholinesterase catalytic subunits of the malaria vector Anopheles gambiae

Dear Editor, Acetylcholinesterase （ACHE） hydrolyzes the neurotransmitter acetylcholine at cholinergic synapses in the central nervous system （Toutant, 1989）. Inhibition of the enzyme in insects could lead to the death of insects rapidly; thus AChE has been a molecular target for developing insecticides.

Arylalkalamine N-acetyltransferase-1 functions on cuticle pigmentation in the yellow fever mosquito,Aedes aegypti

Arylalkylamine N-acetyltransferase(aaNAT)catalyzes the acetylation of dopamine,5-hydroxy-tryptamine,tryptamine,octopamine,norepinephrine and other ary-lalkylamines to form respective N-acetyl-arylalkylamines.Depending on the products formed,aaNATs are involved in a variety of physiological functions.In the yellow fever mosquito,Aedes aegypti,a number of aaNATs and aaNAT-like proteins have been reported.However,the primary function of each individual aaNAT is yet to be identified.In this study we investigated the function of Ae.aegypti aaNAT 1(Ae-aaNATl)in cuticle pigmentation and development of morphology.Ae-aaNAT1 transcripts were detected at all stages of development with highest expressions after pupation and right before adult eclosion.Ae-aaNATl mutant mosquitoes generated using clustered regularly interspaced palindromic repeats(CRISPR)-CRISPR-associated protein 9 had no obvious effect on larval and pupal development.However,the mutant mosquitoes exhibited a roughened ex-oskeletal surface,darker cuticles,and color pattern changes suggesting that Ae-aaNAT1 plays a role in development of the morphology and pigmentation of Ae.aegypti adult cuticles.The mutant also showed less blood feeding efficiency and lower fecundity when compared with the wild-type.The mutation of Ae-aaNAT1 influenced expression of genes involved in cuticle formation.In summary,Ae-aaNAT1 mainly functions on cuticular pigmentation and also affects blood feeding efficiency and fecundity.