Characterization of a honey bee Toll related receptor gene Am18w and its potential involvement in antimicrobial immune defense

Abstract

-Toll receptors are involved in intracellular signal transduction and initiation of insect antimicrobial immune responses. Here we report the isolation and characterization of a novel gene (Am18w) from honey bee Apis mellifera, which encodes for the Toll-like receptor and shares a striking 51.4% similarity with Bombyx mori 18-wheeler, 46.6% with Drosophila Toll-7 receptor and 42.5% with Drosophila 18-wheeler. The sequence analysis of the deduced 18W protein revealed a conserved TollInterleukin-Resistance signaling domain (TIR) characteristic of signal transducing receptors found in Toll and mammalian interleukin 1 (IL-1) receptors. The expression profiles of the honey bee Toll-like receptor gene Am18w were examined in all developmental stages, before and after immune challenge. Here we demonstrate that injection of a dsRNA probe into honey bee larvae successfully disrupts the endogenous mRNA of the target gene and allows us to examine the effects of Am18w gene silencing (RNAi) on the expression level of antimicrobial peptides.Toll receptor / gene silencing / antimicrobial peptides / immune response / honey bee / Apis mellifera

Detailed proteome mapping of newly emerged honeybee worker hemolymph and comparison with the red-eye pupal stage

“…They are known to play an important role in insect immunity and development (Evans et al 2006). Some TLRs were found to be involved in insect intracellular signal transduction and the initiation of the insect antimicrobial immune response (Aronstein and Saldivar 2005;Evans et al 2006;Flenniken and Andino 2013). Future observations of toll-like 13 after an immune challenge could demonstrate its function in the pathogen reorganization pathway.…”

RNA interference in honeybees: off-target effects caused by dsRNA

“…Some of them manipulated eggs or applied dsRNA to larvae either by feeding or injections (Aronstein and Saldivar 2005;Beye et al 2003;Aronstein et al 2006;Patel et al 2007;Kucharski et al 2008;Nunes and Simões 2009;Maori et al 2009), whereas there are only very few reports on the successful manipulation of adult individuals (Amdam et al 2003;Farooqui et al 2004;Seehuus et al 2006;Schlüns and Crozier 2007;Gatehouse et al 2004;Müßig et al 2010;Mustard et al 2010). …”

Negligible uptake and transfer of diet-derived pollen microRNAs in adult honey bees

“…In agreement, oral administration of dsRNA appears to be effective at regulation of gene expression in honey bees. [69][70][71][72][73][74][75][76] In addition, high dose injection of dsRNAs into the hemocoel has been used for delivery and inhibition of target genes in multiple tissues in this species [77][78][79][80][81][82][83][84][85][86] independent of the site of injection, demonstrating that these molecules can be efficiently taken up by disparate tissues once in the open circulatory system. Our results, in conjunction with the previous studies using dsRNA in other insect species, suggest that uptake of longer dsRNAs may be more efficient than shorter miRNAs.…”