The influence of predator odours and overcrowded mouse odours on regulation of oestrous cycles in house mice (\u3ci\u3eMus musculus\u3c/i\u3e)

We investigated the influence of chemical signals derived from different sources—urine of feral cats (Felis catus) and urine from overcrowded mice (Mus musculus) on regulation of oestrous cycles in Mus musculus musculus under laboratory conditions. Cat urine and urine from mice housed in overcrowded conditions caused very similar effects. Application of urine from feral cats and from overcrowded conspecifics to the bedding of experimental animals for a period of 21 days caused a significant increase in numbers of animals with extended oestrous cycles. Application of cat urine or overcrowded mouse urine to the bedding of female mice caused an extension of oestrous cycles in 56.0% and 62.5% of tested animals, respectively. The results of the present study and other experimental data from our laboratory may indicate that predator urine and urine from overcrowded conspecifics share the same chemical information

More than smell - COVID-19 is associated with severe impairment of smell, taste, and chemesthesis

Recent anecdotal and scientific reports have provided evidence of a link between COVID-19 and chemosensory impairments, such as anosmia. However, these reports have downplayed or failed to distinguish potential effects on taste, ignored chemesthesis, and generally lacked quantitative measurements. Here, we report the development, implementation, and initial results of a multilingual, international questionnaire to assess self-reported quantity and quality of perception in 3 distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19. In the first 11 days after questionnaire launch, 4039 participants (2913 women, 1118 men, and 8 others, aged 19-79) reported a COVID-19 diagnosis either via laboratory tests or clinical assessment. Importantly, smell, taste, and chemesthetic function were each significantly reduced compared to their status before the disease. Difference scores (maximum possible change ±100) revealed a mean reduction of smell (-79.7 ± 28.7, mean ± standard deviation), taste (-69.0 ± 32.6), and chemesthetic (-37.3 ± 36.2) function during COVID-19. Qualitative changes in olfactory ability (parosmia and phantosmia) were relatively rare and correlated with smell loss. Importantly, perceived nasal obstruction did not account for smell loss. Furthermore, chemosensory impairments were similar between participants in the laboratory test and clinical assessment groups. These results show that COVID-19-associated chemosensory impairment is not limited to smell but also affects taste and chemesthesis. The multimodal impact of COVID-19 and the lack of perceived nasal obstruction suggest that severe acute respiratory syndrome coronavirus strain 2 (SARS-CoV-2) infection may disrupt sensory-neural mechanisms. © 2020 The Author(s) 2020. Published by Oxford University Press. All rights reserved

Predator presence affects the reproductive success of prey in outdoor conditions

The reproductive outcomes of laboratory rats (Rattus norvegicus) housed at different distances (2, 20 and 80 m) from a predator (Lynx lynx) were investigated. Virgin female (n = 120) and m3ie (n = 40) rats of an outbred laboratory population were used for the experiments. Groups of rats (one male and three females) were housed in standard cages in close proximity to the predator Litter size, sex ratio. number of live pups, number of placental scars and corpora lurea were counted; and pre- and post-implantation losses were calculated for each female. The reproductive success of females, estimated as the number of live pups per female, was significantly higher in both control groups (20 and 80 m) than in both experimental Eraups (2 and 2 m). Equal numbers of corpora lutea in all groups but different numbers of placental scars between control and experimental groups indicated higher pre-implantation losses in the experimental groups. Post-implantation losses were also higher in both experimental groups. Total losses (calculated as a difference between the number of corpora lutea and live pups) were twice as high in experimental groups. Reproductive success of rats depended on concentrate/intensity of predator scents: when concentration/intensity was higher, the number of live pups was less and the total loss was higher

Predator odours as reproductive inhibitors for Norway rats

We examined the influence of predator odor on reproductive output of Norway rats (Rattus norvegicus). Naive laboratory rats responded to predator chemical cues with reduced litter sire and skewed sex ratio. We found that exposure to predator urine had its greatest effect on implantation and maintenance of implantation when predator urine was applied to the bedding of rats during the first third of gestation. Based on the physical appearance of corpora lutea and uterine implantation scars, we found that the reduction in litter sire was due to resolution of the embryos during the early part of gestation. Subsequently, we discovered that the reduction in litter sizes in rats exposed to predator urine could be attributed to suppressed progesterone levels affecting implantation of embryos. Chronically high corticoslerone levels did not suppress reproductive output. Suppression of reproduction also occurred when rats were exposed to urine of conspecifics housed under high population densities. The evolutionary adaptive response for reduced litter sire is to produce high-quality offspring in an environment where food resources are scarce. The fact that rats respond to certain chemical signals in predator urine in a similar fashion may be fortuitous, and may have more to do with the coincidence that the urine contains similar cues resulting from protein digestion in carnivores and protein catabolism in nutritionally deprived rodents, rather than specific predator-prey adaptations

Roles of the main olfactory and vomeronasal systems in the detection of androstenone in inbred strains of mice

We investigated the role of the main olfactory and accessory olfactory systems (MOS and AOS respectively) in the detection of androstenone. We used the following experimental approaches: behavioral, surgical removal of the vomeronasal organ (VNX) followed by histochemical verification and Fos immunohistochemistry. Using a Y-maze paradigm we estimated sensitivity of NZB/B1NJ and CBA/J mice to androstenone. CBA mice were 2,000-fold more sensitive to androstenone than NZB mice. VNX caused a 4- to16-fold decrease in sensitivity to androstenone in highly-sensitive CBA mice, but did not affect thresholds in NZB mice. Results indicate the involvement of the MOS and AOS in the detection of androstenone. We observed a specific pattern of Fos-positive cells in the main olfactory bulb of CBA mice but not in NZB mice subsequent to exposure of mice to androstenone; the compound activated cells in the accessory olfactory bulb in both strains of mice, indicating the involvement of the vomeronasal organ. Patterns of Fos-positive cells in the vomeronasal organ were recorded subsequent to exposure to androstenone. Fos-positive receptor cells in the vomeronasal organ of CBA and NZB mice were different, in CBA mice Fos-positive cells were noted in both the basal and apical zones, however, in NZB mice activation was observed only in the apical zone [Current Zoology 56 (6): 813–818, 2010]

Dataset on assessing olfactory function in the residents of Central Russia using the University of Pennsylvania Smell Identification Test

Data were acquired via sensory testing of olfactory function in 252 adult residents of Central Russia (18–87 years old), including groups from urban and rural areas. The 40-item North American version of the University of Pennsylvania Smell Identification Test (UPSIT) was used. The test alternatives were initially translated into Russian by the authors with minor adaptations. We followed the test procedure recommended by the manufacturer and introduced additional tasks. Familiarity with odor names and consistency with the pre-existing concepts for the test odor items were determined using multiple response questions. Intensity ratings for the UPSIT odorants were obtained using 4-point categorical scale for a subset of the participants. Demographic data and other relevant characteristics of the study population were collected using an adapted translation of the questionnaire included with the test. Descriptive statistics of the collected data are presented in this article. The dataset may be reused for evaluating the impact of various factors, such as cultural context, age, sex, environment, and smoking habits, on the perception of specific odorants as well as on general olfactory function (determined by the number of recognized test items). The data may find its application in the clinical practice of otolaryngologists and neurologists who work with the ethno-cultural group in Russia and all over the world. The dataset can also be used for development of new diagnostic tools for olfactory dysfunction