Abstract
Aquaporins (AQPs) are integral membrane proteins belong to the Major Intrinsic Proteins (MIP) superfamily identified in different tissues from all living organisms including mammals, plants, invertebrates and microorganisms. Only few AQPs isolated and studied from terrestrial insects. In the present study, we report the cloning of a partial cDNA sequence of AQP1 gene from Spodoptera littoralis. The cDNA is 1148bp with an open reading frame of 684bp encoding for 227 amino acids with similarity of 98% and 76% to Spodoptera litura and Grapholita molesta, respectively. Protein structure analysis showed the presence of conserved features found in all studied AQPs such as six transmembrane domains, two conserved motifs of NPA, and the aromatic/arginine (ar/R) selectivity filter. Our study revealed that AQP1 gene is expressed in all insect developmental stages (eggs, larvae, pupae, and adults including males and females). Furthermore, AQP1 expression was detected in tissues of the digestive and excretory system (foregut, midgut, hindgut and Malpighian tubules) of fourth, fifth and sixth larval instars. Gene expression was also detected in the reproductive system of adult females and males. Therefore, we suggest that this AQP1 gene has critical role in maintaining water balance in Spodoptera littoralis insects.