Peripheral processes in insect olfaction.
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Biomedical subjects
M Stengl
Publications and source records attributed to M Stengl.
Olfactory receptor neurons from antennae of developing male Manduca sexta respond to components of the species-specific sex pheromone in vitro.
Male-specific olfactory receptor neurons, dissociated from developing antennae of the moth Manduca sexta and grown in long-term primary cell culture, can respond to at least one component of the female moth's sex-pheromone blend with the opening of a nonspecific cation channel. This response does not require the coapplication of pheromone-binding protein.
4-Aminopyridine↗
Ionic currents of cultured olfactory receptor neurons from antennae of male Manduca sexta.
Whole-cell and single-channel voltage-clamp techniques were used to identify and characterize the ionic currents of insect olfactory receptor neurons (ORNs) in vitro. The cells were isolated from the antennae of male Manduca sexta pupae at stages 3-5 of adult development and maintained in primary cell culture. After 2-3 weeks in vitro, the presumptive ORNs had resting potentials of -62 +/- 12 mV (n = 18) and expressed at least 1 type of Na+ channel and at least 3 types of K+ channels. Na+ currents, recorded in the whole-cell mode, were reversibly blocked by 0.1 microM tetrodotoxin. The predominant type of K+ channel observed was a voltage-activated K+ channel (gamma = 30 pS) with characteristics similar to those of the delayed rectifier. The activity of the 30-pS K+ channel could be inhibited by the application of nucleotides to the cytoplasmic face of inside-out patches of membrane. The nucleotides had relative potencies as follows: ATP greater than cGMP greater than cAMP, with an inhibition constant for ATP of Ki = 0.18 mM. Raising the intracellular Ca2+ concentration from 0.1 to 5 microM induced the opening of a Ca2(+)-activated K+ channel (gamma = 66 pS at 0 mV) that had a low voltage sensitivity. A third, transient type of K+ channel (gamma = 12-18 pS) could be activated by depolarizing voltage steps from very negative resting potentials. Properties of this channel were similar to those of the "A-channel." These results support the conclusion that M. sexta ORNs differentiate in vitro and provide the basis for studying primary mechanisms of olfactory transduction.
Animals↗
Acetylcholinesterase activity in antennal receptor neurons of the sphinx moth Manduca sexta.
We have used a cytochemical technique to investigate the distribution of acetylcholinesterase (AChE) activity in the antenna of the sphinx moth Manduca sexta. High levels of echothiophate-insensitive (presumably intracellular) AChE activity were found in six different types of antennal receptors localized in specific regions of the three antennal segments of the adult moth. Mechanosensory organs in the scape and pedicel, the Böhm bristles and Johnston's organ, are innervated by AChE-positive neurons. In each annulus of the antennal flagellum, AChE-positive neurons are associated with six sensilla chaetica and a peg organ, probably a sensillum styloconicum. At least 112 receptor neurons (8-10 per annulus) innervating the intersegmental membranes between the 14 distalmost annuli also exhibit high levels of echothiophate-resistant AChE. In addition, each annulus has more than 30 AChE-positive somata in the epidermis of the scale-covered (back) side of the flagellum, and 4 AChE-positive somata reside within the first annulus of the flagellum. Since none of the olfactory receptor neurons show a high level of echothiophate-resistant AChE activity, and all known mechanoreceptors are AChE-positive, apparently "intracellular" AChE activity in the antenna correlates well with mechanosensory functions and is consistent with the idea that these cells employ acetylcholine as a neurotransmitter.
Acetylcholinesterase↗
Insect olfactory neurons in vitro: morphological and immunocytochemical characterization of male-specific antennal receptor cells from developing antennae of male Manduca sexta.
Sex-pheromone components released by Manduca sexta females are detected solely by male-specific olfactory receptor neurons that innervate long sensilla trichodea on the male antennae. To facilitate studies of the development and physiology of these receptor cells, we have produced primary in vitro cultures of cells dissociated from pupal male antennae. These cultures comprise several morphological types of cells, 2 of which have been characterized immunocytochemically with a pair of monoclonal antibodies that were shown previously to recognize certain antigens in olfactory receptor neurons at defined stages of development. The good correlation between in vivo and in vitro expression of these antigens suggests that the immunocytochemically recognized cells are olfactory receptor neurons that follow at least partially their normal course of differentiation in vitro.
Animals↗