Cell responses to single pheromone molecules may reflect the activation kinetics of olfactory receptor molecules.

Olfactory receptor cells of the silkmoth Bombyx mori respond to single pheromone molecules with "elementary" electrical events that appear as discrete "bumps" a few milliseconds in duration, or bursts of bumps. As revealed by simulation, one bump may result from a series of random openings of one or several ion channels, producing an average inward membrane current of 1.5 pA. The distributions of durations of bumps and of gaps between bumps in a burst can be fitted by single exponentials with time constants of 10.2 ms and 40.5 ms, respectively. The distribution of burst durations is a sum of two exponentials; the number of bumps per burst obeyed a geometric distribution (mean 3.2 bumps per burst). Accordingly the elementary events could reflect transitions among three states of the pheromone receptor molecule: the vacant receptor (state 1), the pheromone-receptor complex (state 2), and the activated complex (state 3). The calculated rate constants of the transitions between states are k(21)=7.7 s(-1), k(23)=16.8 s(-1), and k(32)=98 s(-1).

[Functional properties of chemoreceptor systems]. / Funktsional'ye svoistva khemoretseptornykh sistem.

It is proposed that the majority of organisms with developed sensory chemoreception possesses two distinct systems of chemical sensitivity performing different tasks. The first system (taste) serves for perception of alimentary substances -- metabolites, or dangerous compounds. The second one (olfaction) perceives metabolically neutral substances which serve as pure signals. All other features of these two systems of chemoreception are considered as secondary, resulting from the main task of each system. In particular, the signal function of olfaction demands sufficiently high sensitivity and a large number of individually recognizable stimuli. The physical state of olfactory stimulants (vapours or solutions) is non-essential. Arguments are presented showing the existence of contact chemoreception with pure signal function both invertebrates and in invertebrates which serves as "contact olfaction". Several problems of chemical communication in animals are discussed, in particular, the role of chemoreception systems in the perception of pheromones and also different kinds of sensory analysis involved in the recognition of chemical stimuli.

[Electrophysiological study of sex pheromone reception in the boar, Sus scrofa]. / Elektrofiziologiceskoe issledovanie retseptsii polovogo feromona khriaka Sus scrofa.

Electroolfactograms were recorded in isolated olfactory epithelium of pigs, both females and castrated males, of various age. The boar pheromone, 5 alpha-androst-16-en-3-one, elicited negative electrical responses up to 2 mV in many preparations. The threshold response corresponded to as low as 10(-9) g of the pheromone on a filter paper. The specific anosmia to the boar pheromone was discovered in few preparations, where responses to the pheromone were absent and the sensitivity to common odour substances (butyl acetate, camphor, butyric acid, etc.) was unchanged.

[Polarization of nerve terminals induced by direct electrical stimulation of frog skeletal muscle]. / Poliarizatsiia nervnykh terminalei, vyzvannaia priamoi élektricheskoi stimuliatsiei skeletnoi myshtsy liagushki.

Direct electrical stimulation (20-200/sec) of the frog skeletal muscle elicited a slow electrical response of motor nerve terminals reflecting a hyperpolarization shift of their membrane potential. A new technique for dissociation of electrical and mechanical activities of muscular fibers revealed hyperpolarization of motor terminals due to a series of APs of the muscular fibers. The terminals hyperpolarizaton response is augmented by 2-3 times with 10 mM of theophyllin. Possible mechanisms of reversed action of active muscular fibers on nerve terminals, are discussed.

[Mechanism of cis-8-dodecenyl acetate suppression of male Laspeyresia pomonella codling moth responses to the sex attractant trans-8,10-dodecadienol]. / O mekhanizme podavleniia tsis-8-dodetsenilatsetatom reaktsii na polovoi attraktant trans-8,10-dodekadienol u samtsov iablonnoi plodozhorki Laspeyresia pomonella.

In field experiments, studies have been made on sex attractiopn of males in the moth L. pomonella. Cis-8-dodecenyl acetate (DDA) was confirmed to be a potent inhibitor of male attraction to the traps baited with virgin females or to a synthetic sex attractant (sex pheromone) trans-8,10-dodecadienol (DDD). DDA also slightly reduced the mating activity under laboratory conditions. The inhibitory effect of DDA on male sex attraction was studied by means of electroantennogram technique. Male antennae were stimulated by DDD and DDA either separately or in combination, DDA vapours being superimposed on the constant DDD background. DDD evoked always negative (excitatory) EAGs, but DDA elicited complex EAGs including both negative and positive (excitatory) EAGs, but DDA elicited complex EAGs including both negative and positive waves. Experiments with double stimulation showed that DDD and DDA produce excitation in different groups of the olfactory receptor cells. Besides, DDA was found to inhibit the EAG evoked by DDD. This inhibition is presumably due to hyperpolarization of the DDD-sensitive cells. Both physiological effects may be involved into inhibition of behavioural reactions in males. The inhibitory mechanism based on competition between DDA and DDD molecules for common receptor sites, seems to be lessprobable.

[Effect of muscle fiber activity on mediator release at frog neuromuscular synapses]. / Vliianie aktivnosti myshechnogo volokna na vydelenie mediatora v nervno-myshechnom sinapse liagushki.

Direct stimulation of muscle, in addition to nerve stimulation, significantly augments the EPP facilitation in the frog neuro-muscular preparation. The mean amplitude of the miniature potentials does not change, at that, which suggests presynaptic nature of the effect. The effect of muscle activity on the quantum content of facilitated EPPs increases with increasing of the stimulation frequency. This suggests that the additional EPP facilitation is due to the electrical rather than mechanical activity of muscular fibers. Experiments with testing EPP delayed for different time intervals after rhythmic stimulation, suggest that acitvity of muscular fibers enhances the probability of trnasmitter release by the presynaptic AP during rhythmic stimulation. The process of transmitter accumulation must simultaneously accelerate. Possible mechanisms of feedback effect of the muscular fibers activity on the state of presynaptic terminals, are discussed.

[Regeneration of olfactory flagella and restoration of the electroolfactogram following application of triton X-100 to the olfactory mucosa of frogs]. / Regeneratsiia oboniatel'nykh zhgutikov i vosstanovlenie élektrool'faktogrammy posle deistviia tritona X-100 na oboniatel'nuiu vystilku liagushki.

A short-tern (1-1.5 min.) irrigation of the olfactory mucose of the frog Rana temporaria with 0.1-0.15% Triton X-100 in Ringer's solution led to the destroying of olfactory flagella but did not damage the olfactory knob and its flagellar basal bodies. Simultaneously, the generator potential of the olfactory cells-elecroolfactogram (EOG)-disappears. The olfactory cells deprived of fragella were able to produce these organelles. This process begins 2 or 3 hours following theflagellum removal, proceeds in some stages and completes within 2 or 3 days. During the flagellum regeneration the ability of olfactory cells to generate EOG is seen to resotre. The data obtained confirm the presence of receptive sites on flagellar surface.