MAGNETIC FLUCTUATIONS AFFECT CIRCADIAN PATTERNS OF LOCOMOTOR ACTIVITY IN ZEBRAFISH (PRELIMINARY DATA)

The locomotor activity of zebrafish (Danio rerio) has a pronounced, well-studied circadian rhythm. Under constant illumination, the period of free-running locomotor activity in this species usually becomes less than 24 hours. To evaluate the entraining capabilities of slow magnetic variations, zebrafish locomotor activity was evaluated at constant illumination and fluctuating magnetic field with a period of 26.8 hours. Lomb-Scargle periodogram revealed significant free-running rhythms of locomotor activity and related behavioral endpoints with a period close to 27 hours. Obtained results reveal the potential of slow magnetic fluctuations for entrainment of the circadian rhythms in zebrafish. The putative mechanisms responsible for the entrainment are discussed, including the possible role of cryptochromes.

INFLUENCE OF DIFFERENT LIGHTING REGIMEN ON THE MORPHOMETRIC CHARACTERISTICS OF NEURONS IN THE PARAVENTRICULAR NUCLEI OF THE RAT HYPOTHALAMUS

Paraventricular nuclei (PVN) of the hypothalamus are the autonomic center forcoordination of functions and consists of a number of neuronal populations - sub-nuclei,which differ in structural and functional features and the nature of nerve connectionswith various parts of the nervous and neuroendocrine systems. When studying stressreactions and actions of the stress-limiting factors, it is important to study subpopulationsof PVN neurons of the hypothalamus, synthesizing stress-releasing hormones, whichinitiate stress reactions of the body. One of the main factors that show a pronouncedeffect in the regulation of ACTH secretion is corticotropin-releasing factor (CRF). TheCRF-immunoreactive tracer was found mainly in the medial small-cell subnucleus of theparaventricular nuclei of the rat hypothalamus. Despite deep and comprehensive studiesof the hypothalamus, until now there are no unifed ideas about its individual reactivityand the degree of involvement of these structures into the stress reaction caused by theprolonged change in the lighting regime.Purpose - to fnd out the effect of different illumination regimes on the morphometriccharacteristics of the medial small-cell subnuclei of the paraventricular nuclei of thehypothalamus of mature and old rats.Material and methods. The experiments were conducted on 72 nonlinear white malerats, divided into 6 series of studies, in each of which the biomaterial sampling wascarried out at 14.00 and 02.00 h using morphometric and statistical research methods.Results. Morphometric assessment of the medial small-cell sub-nuclei of theparaventricular nuclei (msPVN) of the hypothalamus of rats revealed the diurnaldynamics of indices. It has been established that in both old and mature rats, theiraverage volume (p <0.05) signifcantly decreases at 2.00 compared to 14.00 undernormal lighting. The nuclear-cytoplasmatic ratio at 02.00 increases in comparison with14.00 respectively.When the animals were kept under constant illumination, more pronounced changesin the structures under study were established. In particular, the volume of neurons inthe msPVN of the hypothalamus decreases both mature and old rats compared withrats under standard illumination and even more in comparison with rats under lightdeprivation. In accordance with this, the NCR also changes. The average number ofneurons on the standard plane of the histological section also decreases in comparisonwith other illumination regimes. It is also necessary to point out that under conditionsof light stimulation in mature rats in msPVN, the average volume of neurons (p <0.05)noticeably decreases at 02:00 in comparison with 14:00, when the volume of theirnuclei does not change on average during the indicated study periods. This is reflected,respectively, in the NCR change, which increases at 02.00 in comparison with 14.00.As to the old rats, the average neuron volume does not decrease at 2.00 in comparisonwith 14.00 in msPVN neurons at light stimulation, as well as the volume of their neucleichanges, on average, is barely noticeable ,and according to it, NCR at 02.00 remainsstable in comparison with 14.00, and the average quantity of neurocytes in msPVN doesnot change on a standard plane of the histological section during various periods ofthe twenty four hours. At the same time, with various modifcations of the light regime,cytometric parameters of neurons under study in old rats, on average, are signifcantlylower (p <0.001) than those in mature rats.Conclusions. 1. The duration of the photoperiod signifcantly affects the 24 hoursactivity of msPVN in the hypothalamus of mature and old rats. In particular, in bothinvestigated groups of rats, the average volume of neurons (p <0.05) reliably decreasesat 2.00 under normal illumination in comparison with 14.00, and, accordingly, the NCR at 02.00 increases compared to 14.00. All cytometric parameters of their neurons in oldrats are, on average, signifcantly lower (p <0.001) than in mature rats.2. Constant illumination causes more pronounced changes in the morphometricparameters of the msPVN of the hypothalamus than light deprivation. Thus, in maturerats in the msPVN, the average volume of neurons (p <0.05) decreases noticeably at02:00 in comparison with 14:00, which is reflected, respectively, in the change in NCR,which increases at 02:00 compared to 14:00. For old rats, under light stimulation, allthe studied cytometric parameters of their neurons, on average, are signifcantly lower(p <0.001) than those in mature rats.

Activation of Artemia cysts with the use of different substances

The aim of the study was to study the use of hydrogen peroxide and ascorbic acid of different concentrations as an activator for the incubation of artemia cysts. The work was carried out on cysts of artemia taken from several lakes of the Novosibirsk region (Western Siberia). During incubation, a standard method was used: the salinity of the water was 3%, the water temperature was 28□C, continuous aeration was carried out, constant illumination was 2000 lux. An activator was added to the water at different concentrations: ascorbic acid - 0.05, 0.1, 0.5, 1.0 g/l; hydrogen peroxide - 0.4; 0.6; 0.8; 1. The maximum hatching was observed at a concentration of 0.6 g/l of hydrogen peroxide, 82% for cysts from Lake Sakhalin and 68% - from Lake Barbashi. When using ascorbic acid, the maximum hatching of cysts was observed at a concentration of 0.1 g/l: Sakhalin - 81.4, Pokrovka - 75.3 and Barbashi - 66.7%. When using other concentrations of activators, the percentage of cysts hatching decreased. The obtained results indicate the need to select the activating substance and its concentration of activation of cysts for each lake individually.

Morphofunctional State and Circadian Rhythms of the Liver under the Influence of Chronic Alcohol Intoxication and Constant Lighting

A study of the influence of chronic alcohol intoxication, constant illumination and their combined effects on the morphofunctional state of the rat liver and the circadian rhythms (CR) of the studied parameters of the organism was carried out. It was found that both alcohol and constant illumination caused significant changes in the structure of the liver, as well as in the circadian rhythmicity of micromorphometric parameters of hepatocytes, ALT, and total and direct bilirubin rhythms; however, the combined effects of ethanol and constant illumination had the most significant effect on the studied parameters of the organism. These two factors caused disturbances in the circadian rhythms of the micromorphometric parameters of hepatocytes, disruption of the circadian rhythms of total protein, albumin, AST, ALT, and direct and total bilirubin, as well as disturbances in the expression and rhythmicity of the studied clock genes against a background of the development of an inflammatory process in the liver.

Influence of chronic alcoholic intoxication and lighting regime on karyometric and ploidometric parameters of hepatocytes of rats

The features of the diurnal dynamics of the area of rat hepatocyte nuclei and their ploidy were studied under conditions of a standart (fixed) light regime and constant illumination, as well as under chronic exposure to alcohol in the mentioned light regimes. It has been shown that exposure to alcohol and exposure to constant illumination separately lead to a change in the amplitude-phase characteristics of the circadian rhythm of the nucleus area, while the combined effect of these factors leads to a complete destruction of the rhythm, which indicates a violation of adaptation processes. An increase in the average ploidy of hepatocyte nuclei in chronic alcohol intoxication is also shown, while in animals kept under constant illumination without drinking alcohol, the values of this parameter decrease, which indicates a successful course of the adaptation process. The conducted research indicates that the results of karyometric and ploidometric analysis characterize the degree of influence of alcohol intoxication and changes in the light regime on the liver of rats, reflecting the rate of efficiency of adaptation to these factors.

Magnetic fluctuations affect circadian patterns of locomotor activity in zebrafish

The locomotor activity of zebrafish (Danio rerio) has a pronounced, well-studied circadian rhythm. Under constant illumination, the period of free-running locomotor activity in this species usually becomes less than 24 hours. To evaluate the entraining capabilities of slow magnetic variations, zebrafish locomotor activity was evaluated at constant illumination and fluctuating magnetic field with a period of 26.8 hours. Lomb-Scargle periodogram revealed significant free-running rhythms of locomotor activity and related behavioral endpoints with a period close to 27 hours. Obtained results reveal the potential of slow magnetic fluctuations for entrainment of the circadian rhythms in zebrafish. The putative mechanisms responsible for the entrainment are discussed, including the possible role of cryptochromes.

The challenge of designing accelerated indoor tests to predict the outdoor lifetime of perovskite solar cells

Over the past decade, perovskite solar cells have travelled an amazing way towards high efficiency. However, a major roadblock remaining is the operational stability, while achieving technological maturity and proving real-world stability is crucial to gain trust among investors. In that sense, it is of high interest to be able to predict the operational lifetime, which needs to be in the range of years or decades, within an experimentally reasonable timeframe. Yet, peculiarities of perovskite solar cells’ ageing behaviour lead to severe difficulties in translating the results of indoor tests to their outdoor counterpart. In particular, transient processes cause diverse results among different ageing tests.Here, for the first time, we show a complete set of constant illumination indoor testing, cycled illumination indoor testing and real-world outdoor testing on equal in-house devices. Exemplarily, we compare two different types of perovskite solar cells, in which only the hole-transport layer is varied. Despite this small change, the devices show distinctly different transient behaviour. In either case, the commonly used constant illumination experiments fail to predict the outdoor behaviour of the cell. Yet, we observe a good correlation between the cycled illumination test and the outdoor behaviour of one of the two solar cells, while this is not the case for the other system. This result highlights the urge for further research on how to perform meaningful accelerated indoor tests to predict the outdoor lifetime of perovskite solar cells.

EFFECT OF CHRONIC ALCOHOLINTOXICATION AND CONSTANTLIGHTING ON CARDIOVASCULAR PARAMETERS IN MALE R

The aim of the research was to study the effect of chronic alcohol intoxication and constant il-lumination on the circadian rhythms (CR) of some parameters of the cardiovascular system in rats separately, as well as to study the rhythms of these parameters under the combined action of chronic alcohol intoxication (CAI) and constant illumination. It was found that chronic alcohol intoxication CAI at a fixed light regime causes a decrease in heart rate, an increase in SBP and PP; no changes were noted at CAI under constant lighting. At the same time, constant illumina-tion without ethanol exposure results in a decrease in heart rate and an increase in PP. At the same time, CAI with a fixed light regime leads to the destruction of CR of all parameters, except for MBP; at constant illumination with CAI no circadian rhythms of HR, DBP, PP and MBP are detected. Constant illumination leads to the destruction of the CR of PP. Among the remaining CRs, the heart rate rhythm, which is extant in the second group, persists practically unchanged, but the characteristics of all other CRs change significantly in comparison with control.