Vol 478, No 1 (2018)

The spectrum contrast threshold for the comb-filtered signal was measured at various ripple densities in listeners with normal hearing. The lowest spectrum contrast thresholds of less than 0.1 appeared at a ripple density of 3–4 oct^–1. With the ripple density falling down to 1 oct^–1, the threshold increased to 0.17. At the ripple density higher than 4 oct^–1, the threshold was also growing to achieve 1.0 at a density of 7–8 oct^–1. An increase of threshold at high ripple densities can be explained by integration within critical bands. At low ripple densities, the threshold increase may be a result of the lateral suppression that led to sharpening of the spectral contrast.

Based on recently obtained original and published data on the fine structure of the external skeleton of osteostracan agnathans (Osteostraci, Agnatha), possible modes of the formation of their hard cover in the course of the horizontal growth of the exoskeleton are characterized. The developmental models for the formation of various configurations of cephalothoracic shields typical for osteostracans are revealed. It is shown that, in the morphogenesis of the hard cover of this group of early vertebrates, a significant part of the variants of the exoskeleton horizontal growth characteristic of early vertebrates are observed.

The first comparative study of the polychaete pygidial region has been performed using confocal scanning microscopy and immunohistochemical methods. Fundamentally new data has been obtained on the pygidial organization in representatives the Nephtyidae and Syllidae families. Despite differences in the overall morphology of pygidium, it is characterized by a certain structural plan as a whole that can be the basis for that of all polychaetes. Some insignificant differences in the pygidial structure can be either species-specific or consequences of mutations and seem to have no fundamental importance for the general organization.

The effect of male axillary extract on the length and regularity of the menstrual cycle in women was studied in a long-term experiment (9 months). The male secret extract had no statistically significant influence on the menstrual cycle duration in the reproductive-age women (21–45 years) with normal (26–32 days) and regular cycles or in women with abnormally short (<26 days) cycles. In the group of the reproductive-age women with irregular and abnormally long (>32 days) cycles, as well as in the group of the premenopauseage women (46–51 years) with irregular cycles, the secret extract caused a significant shortening of the menstrual cycle as compared to the control. The effect was preserved for at least two months after the exposure completed.

Geometric morphometry has been used to reveal transformations of mandible morphogenesis in the offspring of mole voles resettled to the northern part of the species range from a southern population. The transformations were new compared to both the original (southern) and the aboriginal (northern) populations. A significant increase in the intragroup morphological disparity estimated by the mean nearest neighbor distance (MNND) in the resettled animals compared to both aboriginal populations is an indirect indication of an increased developmental instability in the resettled animals exposed to new climatic conditions.

This is the first study to show that brief pretreatment of potato plants with two brassinosteroids differing in structure causes in plants the ability to react to delayed salt stress by accumulation of compounds with antioxidant activity and by increased salt tolerance.