Spontaneous Ca2+ signals in adult-born juxtaglomerular neurons during their integration into the glomerular layer of the mouse olfactory bulb

Adult mammalian brain is able to generate new neurons throughout life. Adult neural stem cells reside along the walls of the brain lateral ventricles – in a region called subventricular zone (SVZ). In the rodent brain thousands of neuroblasts that are born in the SVZ migrate into the olfactory bulb every day via a pathway that in called rostral migratory stream (RMS), to become functional interneurons – granule cells or juxtaglomerular neurons (JGNs). In the developing nervous system spontaneous calcium transients are believed to be involved in the regulation of neuronal migration, differentiation and survival. In contrast to embryonic development, adult-born neurons have to integrate into the mature environment. It was shown that spontaneous calcium signals are present in adult-born neuroblasts migrating in the rostral extension of the olfactory bulb in-vitro. However, it was not known whether spontaneous calcium signals are present in the immature adult-born JGNs during their integration into mature neuronal circuit in vivo. In the present work in-vivo two-photon calcium imaging was used to study spontaneous calcium signals in adult-born JGNs during their integration into the glomerular layer of the bulb. Adult-born JGNs were labelled via injection of lentivirus encoding the ratiometric fluorescent calcium sensor Twitch-2B into the rostral migratory stream. Twitch-2B is comprised of two fluorescent proteins: mCerulean3 and cpVenusCD that are linked by a calcium-binding region. Therefore, the dynamics of the intracellular calcium concentration is reflected in the corresponding dynamics of the cpVenusCD/mCerulean3 ratio. In order to characterize properties of spontaneous calcium transients, values of the maximal cpVenusCD/mCerulean3 ratio, fraction of time spent in active state and normalized area under the curve were calculated from corresponding traces of spontaneous calcium signals. The results showed that majority of adult-born JGNs studied in awake state between 8th and 11th days post injection (DPI) exhibit spontaneous calcium transients. Acute in-vivo experiments performed under isoflurane revealed that spontaneous calcium signals are blocked by an addition of 2 µM tetrodotoxin (TTX) into the standard extracellular solution. Substantial fraction of immature adult-born JGNs (DPI 9-11) that were spontaneously active in awake sate, showed odorant-evoked calcium transients under 3 component anaesthesia. However, there was no significant difference in the properties of spontaneous calcium transients between odorant-responsive and odorant non-responsive cells. At DPI 9, the majority of adult-born JGNs expressed immature neuronal markers, while expression of the mature markers was very limited. At DPI 20-24, the expression of mature neuronal markers was clearly upregulated. Despite the maturation of the neurochemical properties of adult-born JGNs, there was no significant difference in the percentage of spontaneously active adult-born JGNs in awake state at DPI 8-11 vs. DPI 20-22. However, some maturational dynamics was seen in the pattern of spontaneous calcium signals. Thus, the present work provided in-vivo evidence of the presence of TTX-sensitive spontaneous calcium signals in immature adult-born JGNs; revealed substantial temporal overlap between spontaneous and sensory-evoked activity of immature adult-born JGNs and showed maturational dynamics of spontaneous calcium transients as well as neurochemical properties of adult-born JGNs during their integration into the mature environment of the adult brain

Regenerated Uranium Separation in Matched Abundance Ratio Cascade with Additional Product Flow

This paper addresses known methods used to purify regenerated uranium in single and double cascades. A new method for separating regenerated uranium has been developed that enables a significant reduction of the concentration of 232,234U in the additional product flow. Matched abundance ratio cascades (M∗-cascades) with different key components and additional product flow are used in the new method. Main product flow of the M∗-cascade contains low enriched regenerated uranium. It can be used for reactor fuel production. Purified product can be enriched in the ordinary cascade in compliance with the requirements of ASTM C 996-10 set for isotopes 232,234U in low enriched commercial uranium, which is usually produced from the natural one. Computer experiment based on the new method has been performed. The experiment shows that the best cascade with the maximum flow of the enriched purified product is M∗-cascade with key components 232,236U. © Published under licence by IOP Publishing Ltd

Restoration of the isotopic composition of reprocessed uranium hexafluoride using cascade with additional product

In reprocessed uranium, derived from an impoverished fuel of light-water moderated reactors, there are isotopes of 232, 234, 236U, which make its recycling remarkably difficult. A method of concentration of 235U target isotope in cascade's additional product was proposed to recover the isotopic composition of reprocessed uranium. A general calculation procedure is presented and a parameters' optimization of multi-flow cascades with additional products. For the first time a numeric model of a cascade that uses the cuts of partial flows of stages with relatively high separation factors was applied in this procedure. A novel computing experiment is carried out on separation of reprocessed uranium hexafluoride with providing a high concentration of 235U in cascade's additional product with subsequent dilution. The parameters of cascades' stages are determined so as to allow reducing the 232, 234, 236U isotope content up to the acceptable. It was demonstrated that the dilution of selected products by the natural waste makes it possible to receive a low enriched uranium hexafluoride that meets the ASTM C996-15 specification for commercial grade. © 2020 Korean Nuclear Societ

Role of Neuropeptide Y in Myocardial Contractility of Rats during Early Postnatal Ontogeny

© 2014, Springer Science+Business Media New York. We studied the effect of neuropeptide Y in concentrations of 10–10-10–6 M on myocardial contractility of rats at the age of 7, 21, and 100 days. Studying the isometric contraction of myocardial strips showed that neuropeptide Y decreases the force of myocardial contraction in 7-day-old rat pups. Exogenous neuropeptide Y produced a biphasic effect in 21-day-old rats, which was manifested in the increase and subsequent decrease in myocardial contractility. Neuropeptide Y had little effect on myocardial contractility of 100-day-old animals

Long-term in vivo single-cell tracking reveals the switch of migration patterns in adult-born juxtaglomerular cells of the mouse olfactory bulb

The behavior of adult-born cells can be easily monitored in cell culture or in lower model organisms, but longitudinal observation of individual mammalian adult-born cells in their native microenvironment still proves to be a challenge. Here we have established an approach named optical cell positioning system for long-term in vivo single-cell tracking, which integrates red-green-blue cell labeling with repeated angiography. By combining this approach with in vivo two-photon imaging technique, we characterized the in vivo migration patterns of adult-born neurons in the olfactory bulb. In contrast to the traditional view of mere radial migration of adult-born cells within the bulb, we found that juxtaglomerular cells switch from radial migration to long distance lateral migration upon arrival in their destination layer. This unique long-distance lateral migration has characteristic temporal (stop-and-go) and spatial (migratory, unidirectional or multidirectional) patterns, with a clear cell age-dependent decrease in the migration speed. The active migration of adult-born cells coincides with the time period of initial fate determination and is likely to impact on the integration sites of adult-born cells, their odor responsiveness, as well as their survival rate

Production of highly concentrated intermediate molybdenum isotopes in optimal cascade with two additional product flows

The problem of highly concentrated molybdenum isotopes production in multiflow cascades is considered. A method of the cascade with two additional product flows optimization has been developed. Two components intermediate in weight are concentrated simultaneously in those flows. The optimization problem is solved using a variation of the partial flow cuts of the cascade stages with large separation coefficients. The optimization criterion is the minimum of the stage total feed flow while ensuring a given concentration of isotopes. A computational experiment was carried out to separate a mixture of molybdenum hexafluoride. The experiment demonstrated the features of intermediate components concentrating in additional product flows of the cascade. © 2020 Published under licence by IOP Publishing Ltd

Ordinary Cascades for Purification of Reprocessed Uranium Hexafluoride from 232,234,236U Isotopes

Reprocessed uranium gained from the spent nuclear fuel contains 232,234,236U isotopes within, which considerably hamper its reuse. It is proposed to use an ordinary cascade to reduce the concentration of 232,234U. The output purified from 232,234U is obtained in the cascade waste. The authors analysed the peculiarities of reducing concentration of 236U after the enrichment of reprocessed uranium hexafluoride in terms of 235U in the ordinary cascade and its subsequent dilution. A computational experiment was performed. Parameters of cascade stages were predetermined, which allow to reduce the content of 232,234,236U to an acceptable level. © 2022 Institute of Physics Publishing. All rights reserved

REPROCESSED URANIUM REFINEMENT IN THE MARC-CASCADES WITH INTERMEDIATE PRODUCT

A new method of reprocessed uranium refinement is proposed. The method is based on the calculation of the MARC cascade with intermediate product flow. According to the developed method calculations were made for MARC cascades based on different uranium isotopes. The best cascade was chosen using maximum flow criteria

THE PROBLEM OF ECOLOGICAL EDUCATION AND THE PROSPECTS OF ECOLOGIZATION

Environmental education and upbringing are the basis of the ecological well-being of society, and environmental competence is becoming an important factor in the formation of personality. Today, environmental education in the Republic of Belarus is based on the principle of continuity, it operates at all levels of education and implies continuous replenishment of the population’s knowledge in biology, ecology, environmental protection etcetera. Nevertheless, there are a number of problems that do not allow to fully reveal the potential of environmental education, for example, in higher education institutions. The analysis of syllabus and the rethinking of the educational process will lead to significant progress in the field of education ecologization.Экологическое образование и воспитание являются основой экологического благополучия общества, а экологическая компетентность становится важным фактором становления личности. На сегодняшний день экологическое образование в Республике Беларусь основывается на принципе непрерывности, то есть действует на всех ступенях образования и подразумевает постоянное пополнение знаний населения в областях биологии, экологии, охраны окружающей среды и прочих. Тем не менее, существует ряд проблем, которые не позволяют в полной мере раскрыть потенциал экологического образования, в частности, в высших учебных заведениях. Анализ учебных планов и переосмысление ведения учебного процесса смогут дать значительный прогресс в области экологизации образования