Influence of ionizing radiation on the attractiveness of male mice to chemosignals of intact individuals

Within short-terms after exposure to ionizing radiation, CBA and C57Bl/6 male mice were found not only to retain but also to enhance their attractiveness to chemosignals of intact males of the same genotype (syngenic). It was shown that the time period of higher attractiveness increased with the absorbed dose (from 1 to 6 Gy). Within several days after exposure to 6-Gy irradiation, male mice were temporarily unable to discriminate between chemosignals of syngenic and allogenic (alien genotype) individuals. Unlike male mice of the CBA strain, male mice of the C57Bl/6 strain displayed no changes after exposure to 1-Gy irradiation, but the effect of 2-6 Gy was more persistent. These phenomena can be explained by the lower olfactory reactivity combined with higher radiosensitivity of C57Bl/6 mice. Irradiated male mice temporarily lost their olfactory ability to discriminate the genotype of females' volatile secretions and to distinguish between females' and males' volatile secretions.     

Effects of the olfactory environment and nutrition on the ability of male Mediterranean fruit flies to endure starvation

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is targeted for control using the sterile insect technique (SIT). For this technique to succeed, released males must be able to compete with wild males for copulations. Male success is mediated by survival in the field often in adverse conditions. Manipulation of the postteneral environment experienced by sterile males before release has been shown to affect male sexual success and survival. The objectives of this study were to determine how various diets, combined with exposure to volatiles containing alpha-copaene, affect the ability of male Mediterranean fruit flies (from a wild and two unisexual strains) to withstand starvation. Accordingly, we maintained males on one of eight regimes combing a diet of either sugar, sugar and protein, a protein pulse or apricot, with or without the aroma of the sexual stimulant alpha-copaene. The apricot diet was associated with the lowest ability to resist starvation. The sugar-only diet was associated with the highest ability to resist starvation by sterile males. Exposure to alpha-copaene, in combination with the apricot diet, had a significant negative effect on the ability of males (from all strains) to resist starvation relative to other regimes examined. We conclude that the holding regimes that elicit the best sexual performance from males paradoxically also hasten their demise, probably by initiating an irreversible metabolic cascade. The search for the optimal prerelease regime continues.     

Postradiation volatile secretion of mice attractive for intact individuals

In early period after exposure to a sub-lethal dose (4 Gy) the exposed mice secreted volatile components (in their urine), which were attractive for intact individuals independently of genotype. The postradiation components were more attractive for allogene individuals than for singene ones. This reaction was different in exposed intact mice, which showed singene attractiveness of volatile secretion. Attractiveness of postradiation volatile components differed from the attractiveness of ones secreted after stress.     

Influence of the stage of the cycle on olfactory sensitivity in laboratory mice

Females in estrus showed maximum olfactory sensitivity as judged by their ability in locating the buried bait. The results suggest that olfactory sensitivity in females varies during the stages of the estrous cycle. The findings further indicate that gonadal steroids play an important role in the expression of olfactory sensitivity in females.     

Studies on feminine sexual behavior in the male rat: Influence of olfactory stimuli

The aim of this study was to determine if the display of lordosis behavior in the male rat could be influenced by the olfactory environment. Unexperienced adult male rats were orchidectomized (ORCH). They were primed with 75 μg estradiol benzoate and 1 mg progesterone was injected at an interval of 39 hr following long-term (LT = 3 weeks) or short-term (SHT = 8 hr 30 min) exposure to the odor of male or female urine. For 10 min they were placed in the presence of a “stimulus” male of proven sexual vigor 9 hr 30 min ± 1 hr after progesterone injection. Both LT and SHT exposure to the odor of male urine caused a significant increase in the number of ORCH rats which showed lordosis response to male mounts compared to either the ORCH rats exposed to the odor of female urine or to the controls. Following complete olfactory bulb removal (COBR), no difference was observed in the occurrence of lordosis behavior between the ORCH rats whether or not exposed to the odor of urine. For the ORCH-COBR rats exposed to male urine the proportion of animals responding to mounts did not differ from that of their nonbulbectomized counterparts. In comparing the effects of COBR vs anterior olfactory bulb removal (AOBR) lordosis behavior occurred more frequently in COBR than in AOBR-ORCH rats. The lordosis quotient (LQ) was not affected by exposure to the odor of male urine in the nonbulbectomized ORCH rats. In contrast, it appeared to be higher in both COBR and AOBR animals than in their nonbulbectomized counterparts. The olfactory bulbs were then concluded to inhibit the display of lordosis behavior in the male rat. It was also thought that the olfactory stimuli originating from male urine were capable of releasing the hypothalamic structures involved in the control of lordosis behavior of the male rat from an olfactory inhibitory influence.     

Temporary inhibition by progesterone of sexual behavior in intact male mice

Administration of 0.50 mg or 1.00 mg progesterone (P) daily resulted in suppression of portions of the male sexual repertoire. Mice treated with 0.25 mg P daily behaved like control subjects. Sexual behavior of mice treated with the higher P doses resembled that of controls three weeks after cessation of P treatment. No lasting effects of P on total body weight or on weights of testes or seminal vesicles were detected.     

Odor detection ability and thallium-201 transport in the olfactory nerve of traumatic olfactory-impaired mice

Although olfactory nerve damage is a contributing factor in the diagnosis of posttraumatic olfactory loss, at present, there are no methods to directly assess injury to these nerves. We have shown that following olfactory nerve injury in mice, thallium-201 (201 Tl) transport from the nasal cavity to the olfactory bulb decreases. To determine if olfactory function after nerve injury could be assessed with nasal administration of 201 Tl, we measured the correlation between odor detection ability (ODA) and the rate of transport of 201 Tl in olfactory nerves. Both ODA and 201 Tl transport were measured after bilateral olfactory nerve transection for a 4-week period. Cycloheximide solution was used for ODA against tap water. 201 Tl transport was measured as the ratio of radioactivity in the nasal cavity and olfactory bulb with gamma spectrometry. There was a significant correlation between ODA and the rate of 201 Tl transport in the olfactory nerve. These findings suggest that olfactory function after nerve injury can be objectively evaluated with the nasal administration of 201 Tl.     

Effect of selenium-induced oxidative stress on the oxidation reduction system and reproductive ability of male mice

The present study was carried out to evaluate the effect of selenium (Se)-induced oxidative stress on the oxidation reduction system and the fertility status of male mice. Different levels of Se, a potent antioxidant, were fed in three separate groups for 8 wk to create the different oxidative stress in mice. A significant decrese in the glutathione peroxidase (GSH-Px) in both liver and testis was observed in the Se-deficient (0.02 ppm) group I, whereas enzyme levels in the Se-excess (1 ppm) group were comparable to the Se-adequate (0.2 ppm) group. Glutathione-S-transferase activity was enhanced in group I in comparison to group II; however, no change was seen in group III. The glutathione reductase and superoxide dismutase activities were decreased in the Se-deficient group, whereas the enzyme levels were significantly increased in the Se-excess group. The fertility status of the animals studied in terms of percentage fertility and litter size showed a significant decrease in the reproductive ability of male mice in group I when compared to group II. No changes in the fertility status of animals were observed in group III. Thus, the data clearly indicate the effect of oxidative stress generated by feeding various Se levels on the oxidation reduction system and, consequently, its effect on the reproductive ability of male mice.     

Lordosis behavior in intact male rats: effects of hormonal treatment and/or manipulation of the olfactory system

The aim of this study was to investigate the olfactory mechanisms regulating the display of lordosis behavior in intact Wistar male rats bred in our colony. Gonadally intact males show a low capacity to respond by lordosis to male mounts and were insensitive to manipulations of the olfactory system (exposure to the odor of male urine or accessory bulb removal (AOBR)) which have been previously shown to facilitate the display of lordosis behavior in orchidectomized animals primed with ovarian hormones. Treatment with either estradiol benzoate (EB) or EB and progesterone (P) consecutively did not render these gonadally intact animals sensitive to the effects of AOBR. By contrast exposure to male urine was capable of facilitating the display of lordosis behavior in intact male rats given EB + P consecutively. These results are discussed in the light of previous findings showing that (1) two inhibitory structures, the accessory olfactory bulb and the septal and preoptic areas, are involved in the control of lordosis behavior in the male rat; (2) the effects of olfactory cues on the display of lordosis behavior are dependent on the action of both EB and P in orchidectomized animals.     

Use of aflatoxin-producing ability medium to distinguish aflatoxin-producing strains of Aspergillus flavus.

Aflatoxin-producing ability medium was tested for its ability to distinguish aflatoxin-positive from aflatoxin-negative strains of Aspergillus flavus in naturally occurring populations from corn at harvest. All of the aflatoxin-positive strains and some of the aflatoxin-negative strains produced aflatoxins when cultured on cracked corn. Although the data indicate that aflatoxin-producing ability medium is not entirely reliable in distinguishing potential aflatoxin-producing strains of A. flavus from nontoxigenic strains, it is significant that the medium did not yield false-positives.     

Effect of cyproterone acetate on the pregnancy-blocking ability of male mice and the possible chemical nature of the pheromone

Even though castration abolished the ability of alien males to induce implantation failure (the Bruce effect) in newly inseminated females, treatment of intact alien males with the steroidal antiandrogen, cyproterone acetate, for 14 days (short term) did not significantly depress their ability to induce the Bruce effect. However, prolonged treatment (42 days) with cyproterone acetate suppressed the pregnancy-blocking ability of alien males to some extent, possibly due to the antigonadotrophic properties of the drug. Ovariectomized alien females treated with implants of testosterone (androgenized females) exhibited the ability to block implantation in newly inseminated females, but concurrent treatment of androgenized females with cyproterone acetate did not depress this ability. The results strongly suggest that the pheromone involved in the male-induced implantation failure is not the product of an androgen-dependent tissue, but is likely to be a product of androgen metabolism.     

Influence of a detergent on the catfish olfactory mucosa

The olfactory mucosa of the catfish (Ictulurus punctatus) has been briefly exposed to various concentrations of the non-ionic detergent Triton X-100. At high concentrations (1–4%) the upper layer of cells constituting the sensory and non-sensory areas of the lamellae is extensively damaged and new receptor cells do not appear in significant number before 2 months after treatment. Respiratory cells regenerate first followed by sustentacular and olfactory receptors. The regenerative process is very similar to that described previously after prolonged contact between the mucosa and ZnSO₄. Low detergent concentrations 0.03 – 0.1% affect only the sensory area. Olfactory and sustentacular microvilli and cilia, are immediately severed by the chemical. Regeneration occurs within the next 4 days. The cellular membranes appear also to be affected. From anatomical, electrophysiological and biochemical studies both in vivo and in vitro, it can be hypothesized that receptors involved in the transduction process are solubilized by the detergent but reappear at a level corresponding to 50–60% of their original activity within 2 h.Proteins, having an amino acid binding effectiveness correlated to the amino acid electrophysiological activities measured in vivo, can be isolated from the solubilized material. Further studies will be necessary to confirm that some of these molecules are involved in the olfactory transduction mechanism.     

Preliminary experiments on the olfactory responses of Pterostichus melanarius Illiger (Coleoptera: Carabidae) to intact plants

1 In two successive years, the olfactory responses of Pterostichus melanarius Illiger (Coleoptera: Carabidae) to intact cabbage and white clover plants were studied, using a four‐arm olfactometer. 2 The first set of experiments tested the response to the odours of cabbage, white clover and the two plants grown together against potting compost; in the second and third sets of experiments, white clover and cabbage were tested, respectively. 3 The results indicate that female P. melanarius individuals are arrested by the combined odours of cabbage and white clover, spending significantly more time in the cabbage with white clover odour field than in either the cabbage, white clover or control odour fields. 4 Similar results were not found for males. 5 Cabbage plants alone did not elicit significant responses in either sex. 6 White clover alone did not elicit significant responses by females and the responses of males were not uniform in the two successive years.     

Odorant-specific patterns of sniffing during imagery distinguish 'bad' and 'good' olfactory imagers

There are large individual differences in the self-reported ability to form vivid olfactory mental imagery. Based on such self-reports, subjects have been classified as 'bad' or 'good' imagers. The present study examined whether a differential strategy in re-enacting the olfactomotor response during imagery may explain the dissociation between 'bad' and 'good' olfactory imagers. As previously reported, odor imagery was accompanied by sniffing. Although 'bad' and 'good' olfactory imagers did not differ in their overall sniffing volume, they used different strategies when re-enacting the motor component of olfaction during imagery. Particularly, as in real perception, 'good' but not 'bad' imagers generated bigger sniffs when imagining a pleasant smell compared with an unpleasant smell (P<0.02). Furthermore, preventing sniffing significantly hampered mental imagery of pleasant odors in 'good' but not 'bad' imagers (P<0.03). Taken together, these results suggest (i) the validity of the dissociation between 'bad' and 'good' olfactory imagers as revealed by self-report; (ii) that sniffing may be a causal factor in the creation of olfactory imagery; and (iii) that sniff measurements may serve as a reliable non-verbal tool in exploring individual differences in odor imagery.