Marina Caillaud presented a poster entitled, “A molecular approach to the induction of host specificity in the sensitivity of sensilla styloconica in the larvae of Manduca sexta”. The presentation was at the Annual Meeting of the International Chemical Ecology Society, Washington, DC.
Marta L. del Campo, Carol I. Miles, and Marina Caillaud
Larvae of the moth Manduca sexta are facultative specialists in the plant family Solanaceae. After few days from hatching, larvae feeding on solanaceous foliage become specialist feeders, while those feeding on non-solanaceous foliage or artificial diets remain polyphagous. The induced feeding preference of M. sexta larvae involves the formation of a recognition template to the host recognition cue indioside D, a steroidal glycoside so far only found in Solanaceae.
The induction of host specificity in M. sexta is at least in part a result of chemosensory tuning to indioside D in 50% of the taste receptor cells located in two pairs of taste sensilla, the lateral and medial sensilla styloconica. The information transduced by these taste receptor cells is sufficient and necessary for the feeding preferences of host-restricted M. sexta larvae.
We hypothesize that these changes in test receptor responses may be due at least in part to changes in gene expression on these cells. To test this hypothesis, two animal populations were reared to their fifth stadium, one polyphagous population reared on wheat germ artificial diet, and the other specialist population reared on potato foliage. Two types of tissues were collected from the fifth instars: maxilla, containing the sensilla styloconica as well as the maxillary palp, and the dorsal abdominal horn as a control tissue, which does not contain chemoreceptors. mRNAs were extracted from tissues and by differential display technique cDNA fragments were generated by RT-PCR followed by amplification.
The obtained cDNA fragments from each of the tissues and animal populations were compared on polyacrylamide and agarose gels. The differentially expressed cDNA were recovered from polyacrylamide and agarose gels and individually re-amplified, subjected to Northern Blot, followed by sequencing. Here we present our results and place them in context of taste transduction and feeding behavior.