Journal of Evolutionary Biochemistry and Physiology

The review addresses current concepts on the origin and functions of Schwann cells (SCs) as well as phenotypic characterization of their precursors at different ontogenetic stages. The necessity of versatile fundamental exploring SCs is dictated by searching for novel ways to stimulate the recovery of peripheral nerve fibers, including cell and gene therapy. Being a major structural component of the nerve, SCs have a decisive influence on degenerative and reparative processes therein. Particularly accentuated is the lack of knowledge of the molecular mechanisms that regulate SCs differentiation at different ontogenetic stages and their plasticity in the pathology of nerve conduction.

The fatty acid (FA) composition of eggs and sperm, as well as the gonadal FA dynamics, were studied for the first time in the mussel Mytilus galloprovincialis Lam. (1819) at different stages of its sexual maturation. Currently, this species is being successfully cultivated in the Black Sea. As exemplified by 22 extracted and identified FAs having a chain length of 14–22 carbon atoms, the gonadal FA composition was shown to depend on the mollusk’s sexual maturation stage. An analysis of FA proportions demonstrated that saturated fatty acids (SFAs) account for 100% of the total FA content in female gonads at stages 1 to 3 and in male gonads at stages 1 and 5. The relative SFA content in eggs exceeds that in sperm. Mono- and polyunsaturated FAs (MUFA and PUFA) are characteristic both of male gonads and sperm in which their total content is higher than in female gonads and eggs. The FA content of the gonads and gametes in M. galloprovincialis follows the natural seasonal reproductive cycle of these bivalve mollusks.

Using indirect calorimetry, we examined 1632 young males aged 17 to 21 years, belonging to the Europeoid (Caucasian) race and residing permanently in the city of Magadan. Depending on the duration of adaptation to the conditions of the Northeast of Russia, all male subjects were divided into 3 groups of generation 1, 2 and 3 descendants and a group of newcomers (migrants or adaptants) residing in the Magadan Region for a short period of time (generation 0). It was established that in the lineage from generations 0 to 3 there occurred an optimization of the ventilatory characteristics of the external respiration apparatus aimed at cutting respiratory heat losses during adaptation to extreme conditions of the Northeast, i.e. a decrease in the tidal volume, tidal minute volume, and respiratory rate. Relevant rearrangements of the ventilatory pattern in subjects with a longer duration of residence under the same extreme conditions are paralleled by an improvement of oxygen transport and more efficient use of each respiratory cycle.

The influence of long-term light deprivation (1 and 4 months) on the latency of leaving a start chamber (t₁), feeding latency (t₂), and food intake (or ration, R) was studied in carp Cyprinus carpio juveniles injected with serotonin (5-HT), as observed during 96 h post injection. It was found that 5-HT has no significant effect on t₁ regardless of the illuminance regime (constant dark in experiment vs. alternating light/dark in control) while exerting a maximum effect on t₂. One hour after 5-HT injection, t₂ increases 5 times in fish deprived of light for 1 month and 11.6 times in those deprived of light for 4 months as compared to the control group. A significant 5-HT-induced decrease in R was observed after 1 month both in experimental and control groups and after 4 months in the experimental (light-deprived) group only. Possible mechanisms underlying the effect of 5-HT on the above parameters of fish feeding behavior under conditions of long-term light deprivation are discussed.

In clinical practice, luteinizing hormone (LH) and chorionic gonadotropin (CG) are used as activators of the LH receptor, leading to the stimulation of gonadal steroidogenesis. However, high doses of gonadotropin preparations cause a number of side effects. Here we demonstrate that the pretreatment of male rats with TP03, an allosteric agonist of the LH receptor, at doses of 7.5–25 mg/kg significantly increases the testosterone production-stimulating effect of CG administered at a dose of 50 IU/rat, which is twice as low as that inducing a maximum steroidogenic effect. We assume that this is due to additivity of the CG and TP03 effects, as well as the potentiating effect of TP03 on CG signaling pathways. Three hours after CG administration to TP03-pretreated rats, the activation pattern of the genes of steroidogenic enzymes and LH receptor exhibits specific changes which mainly concern 3p-dehydrogenase gene expression. The obtained data indicate a prospectivity of TP03 and CG co-application allowing the effective dose of gonadotropin preparations to be reduced.