Glucose transporter 8 (GLUT8) from the red imported fire ant, Solenopsis invicta buren (Hymenoptera: Formicidae)

Abstract

We have cloned the fire ant glucose transporter 8 (GLUT8) cDNA providing the first molecular characterization of a GLUT8 in insects. Glucose is a poly-alcohol and, due to its high hydrophilicity, cannot move across cell membranes. GLUT8 is a putative facilitative transporter for the cellular import and export of glucose. The complete 2,974-bp cDNA encodes a 501-residue protein with a predicted molecular mass of 54.8 kDa. Transcripts were detected in the brain, midgut, hindgut, Malpighian tubule, fat body, ovary, and testis. The highest transcriptional expression was found in fat body. Northern blot analysis revealed different transcript sizes in mated queen brains, alate female ovaries, and male testes. We propose that four other sequences obtained from insect genome projects from the honey bee Apis mellifera (ENSAPMP00000006624), the malaria mosquito Anopheles gambiae (EAA11842), and the fruit fly Drosophila melanogaster (AAQ23604 and AAM52591) are likely the orthologues of the fire ant GLUT8. Phylogenetic relationships in insect glucose transporters are presented.

The trehalose transporter 1 gene sequence is conserved in insects and encodes proteins with different kinetic properties involved in trehalose import into peripheral tissues

“…A sugar transporter designated fire ant GLUT8 cDNA (GenBank accession no. AY911645) was recently isolated from the hymenopteran S. invicta (Chen et al, 2006), and this deduced sequence corresponded to Q2KKJ2_SOLIN in Pfam v22.0. A phylogenetic analysis revealed that the amino acid sequence of Q2KKJ2_SOLIN was more similar to that of TRET1 than to that of other sugar transporters, including human GLUT8 ( Supplementary Fig.…”

“…4A and B). In addition, the Hymenopteran fire ant GLUT8 transcripts mentioned above appeared more abundant in the fat body (Chen et al, 2006) and DmTret1-1 is abundant in the larval fat body according to FlyAtlas (keyword: CG30035). In insects, taking into account the physiological and biochemical roles of the fat body, where trehalose is synthesized (Becker et al, 1996), such tissue localizations provide strong evidence that TRET1 is involved in the facilitation of trehalose transport from the fat body into the haemolymph, thereby maintaining trehalose levels in the haemolymph.…”

Unexpected similarity of intestinal sugar absorption by SGLT1 and apical GLUT2 in an insect (Aphidius ervi,Hymenoptera) and mammals

“…The few initial studies (15,45,51,52) suggested the absence of sugar transporters in the insect gut and described the absorption as a passive, possibly diffusional, process sustained by the extremely rapid transformation of glucose into the disaccharide trehalose. However, functional and molecular studies have recently demonstrated that sugar transporters belonging to the GLUT family are present in insects of different orders (9,13,19,36,58), although their membrane localization in the absorbing cells has been reported only in one case (9).…”

Identification of a novel sodium-dependent fructose transport activity in the hepatopancreas of the Atlantic lobsterHomarus americanus

“…Early studies with insect gut suggested that sugars were absorbed totally by diffusion without involving carrier proteins in the process (Treherne, 1957;Treherne, 1958). More recently, several studies involving both physiology and molecular biology have described a number of sugar transporters of the GLUT family in insects from several different orders (Caccia et al, 2005;Chen et al, 2006;Escher and RasmusonLestander, 1999;Pascual et al, 2006;Wang and Wang, 1993). The first report describing a detailed model for carrier-mediated sugar movement across an absorbing insect epithelium was published in 2007 (Caccia et al, 2007).…”