Distinct projections of two populations of olfactory receptor axons in the antennal lobe of the sphinx moth Manduca sexta.

The central projections of olfactory receptor cells associated with two distinct types of antennal sensilla in the sphinx moth Manduca sexta were revealed by anterograde staining. In both sexes, receptor axons that arise from sexually isomorphic, type-II trichoid sensilla (and possibly some basiconic sensilla) project to the spheroidal glomeruli in the ipsilateral antennal lobe. Each axon terminates in one glomerulus. Axons from a limited region of the antenna project to glomeruli throughout the lobe, arguing against strict topographic mapping of antennal receptor cells onto the array of glomeruli. Axons of sex-pheromone-selective receptor cells in the male-specific type-I trichoid sensilla project exclusively to the sexually dimorphic macroglomerular complex (MGC). Axons from sensilla on the dorsal surface of the antenna are biased toward the medial MGC and those from ventral sensilla, toward the lateral MGC. Some receptor-cell axons branch before reaching the MGC, but their terminals are always confined to one of the two main glomerular divisions of the MGC, the cumulus and toroid. These findings confirm that primary-afferent information about pheromonal and non-pheromonal odors is segregated in the antennal lobe and suggest that there is a functional correspondence between particular olfactory receptor cells and specific glomeruli.

Discovery of D-amino-acid-containing ligands with selectide technology.

When all L-amino acid (aa) random peptide libraries synthesized on solid-phase particles were screened (Selectide Technology), we identified several peptide ligands (YG_F_) that interacted specifically with an anti-beta-endorphin monoclonal antibody (clone 3E7) (single-letter aa symbols; symbols '_' indicate variable aa). Here, we report on the screening of three different D-aa-containing pentapeptide libraries (XxXxX, xXxXx and xxxxx, wherein X = L-aa, and x = D-aa) with the same antibody, in which several D-aa-containing ligands were identified. The binding affinities of many of these D-aa-containing ligands were as least two orders of magnitude lower than that of YGGFL, for which the Ki is 17.5 nM.