Cloning and functional expression of intracellular loop variants of the honey bee (Apis mellifera) RDL GABA receptor.
The insect GABA receptor, RDL (resistance to dieldrin), plays central roles in neuronal signalling and is the target of several classes of insecticides. To study the GABA receptor from an important pollinator species, we cloned Rdl cDNA from the honey bee, Apis mellifera. Three Rdl variants were identified, arising from differential use of splice acceptor sites in the large intracellular loop between transmembrane regions 3 and 4. These variants were renamed from previously, as Amel_RDLvar1, Amel_RDLvar2 and Amel_RDLvar3. When expressed in Xenopus laevis oocytes, the three variants showed no difference in sensitivity to the agonist, GABA, with EC50s of 29μM, 20μM and 29μM respectively. Also, the potencies of the antagonists, fipronil and imidacloprid, were similar on all three variants. Fipronil IC50values were 0.18μM, 0.31μM and 0.20μM whereas 100μM imidacloprid reduced the GABA response by 17%, 24% and 31%. The possibility that differential splicing of the RDL intracellular loop may represent a species-specific mechanism leading to insensitivity to insecticides is discussed.
Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK.
Jennina
J
Taylor-Wells
Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK.
Joseph
J
Hawkins
Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK.
Claudia
C
Colombo
Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK.
Isabel
I
Bermudez
Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK. Electronic address: a.jones@brookes.ac.uk.
Andrew K
AK
Jones
D000818:Animals; D001516:Bees / Q000235:genetics*; D004026:Dieldrin; D018755:GABA Agonists / Q000494:pharmacology; D019476:Insect Proteins / Q000235:genetics; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D000073943:Neonicotinoids / Q000494:pharmacology; D009574:Nitro Compounds / Q000494:pharmacology; D009865:Oocytes; D020033:Protein Isoforms / Q000235:genetics; D011720:Pyrazoles / Q000494:pharmacology; D018079:Receptors, GABA / Q000235:genetics*; D014982:Xenopus laevis; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D018755:GABA Agonists; D019476:Insect Proteins; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D020033:Protein Isoforms; D011720:Pyrazoles; D018079:Receptors, GABA; C082359:imidacloprid; D005680:gamma-Aminobutyric Acid; D004026:Dieldrin; C082360:fipronil
Apis mellifera; Fipronil; GABA receptor; Imidacloprid; Splice variant; Xenopus oocytes