Cement gland as the adhesion organ in Xenopus laevis embryos

The cement gland in batrachians is a temporal ectodermic organ which is necessary for an embryo's attachment to the substrate. In this review, some notions about the origin of the cement gland of Xenopus laevis frogs, its functioning, genes being expressed in it, and regulation of its formation and development are provided. The role of some homologies of agrgenes of the cement gland in Xenopus laevis is noted at different conditions of other animals and man.     

Effect of adaptation to altitude on the myocardial noradrenaline content and on the resistance of adrenergic mechanisms to acute cardiac overload in rats

The changes of the myocardial noradrenaline concentration and that of protein synthesis in sympathetic neurons innervating the heart were studied in male Wistar rats during adaptation to simulated altitude. Adaptation to hypoxia was achieved by placing animals in a low pressure chamber daily for 5 to 6 hours 5 days a week up to 7.000 m for 11 weeks. After 10 days of exposure a decrease of the noradrenaline concentration in the myocardium was observed, but later the concentration began to increase again and returned to normal values in spite of the altitude stress. The recovery of the noradrenaline concentration was accompanied by an activation of protein synthesis in sympathetic neurons and glial cells of the stellate ganglia innervating the heart. The effect of the preliminary adaptation to simulated altitude was studied in rats with acute cardiac overload produced by aorta coarctation. The preliminary adaptation to hypoxia prevented greatly the reduction in cardiac noradrenaline concentration that usually occurred in control animals in acute cardiac overload.

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Zusammenfassung Die Veränderungen der Noradrenalinkonzentration im Myokard und der Proteinsynthese in den sympathisch innervierten Neuronen des Herzens wurden an männlichen Wistarratten während der Anpassung an simulierte Höhen bis 7000 m untersucht. Zur Höhenanpassung wurden die Tiere täglich 5 – 6 Stunden an 5 Tagen der Woche 11 Wochen lang in einer Unterdruckkammer exponiert. Nach 10 Tagen Höhenexponierung fiel die Noradrenalinkonzentration, danach stieg sie wieder auf normale Werte an trotz Fortsetzung der Unterdruckbelastung. Dies war begleitet von einer Anregung der Proteinsynthese in den das Herz innervierenden Neuronen des Sympathikus, den Gliazellen und des Ganglion stellatum. Vorläufige Höhenanpassung verhütete einen starken Fall des Noradrenalingehaltes im Myokard.

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Resume On examine ici l'incidence d'une période d'acclimatation à une altitude simulée de 7000 m sur les changements de la concentration de la noradrénaline dans le myocarde ainsi que de la synthèse protéinique des neurones innervant le coeur à partir du système nerveux végétatif. Pour ce faire, on s'est servi de rats mâles de Vistar. Pour les acclimater à l'altitude, ces rats furent placés dans un caisson décompressé pendant 5 à 6 heures par jour et cela 5 jours par semaine et durant 11 semaines. Après 10 jours d'exposition à l'altitude, on a pu constater une diminution de la concentration en noradrénaline. Ensuite, cette concentration s'est relevées jusqu'à son niveau normal malgré la prolongation de la contrainte d'altitude. Ces symptomes furent accompagnés d'une accélération de la synthèse protéinique dans les neurones du système sympathique innervant le coeur ainsi que dans les cellules de glia des ganglions en forme d'étoile. En outre, une acclimatation provisoire à un déficit en oxygène a provoqué un abaissement marqué du taux de noradrénaline du myocarde.

     

Prospects of Non-drug Approaches to Alzheimer's Disease

Despite the urgency of the problem of prevention and treatment of neurodegenerative processes underlying Alzheimer's disease (AD) and other severe disorders of the central nervous system, therapeutic and prophylactic potential of drugs is yet insufficient. Numerous adverse effects of the drugs, which might improve cognitive function in patients with AD substantiate serious consideration of measures enhancing adaptive potential and mobilizing self-defense of the body. It is clear now that endogenous defense systems of the brain can limit progression of AD long after the onset of the disease. The measures mobilizing the self-defense include administration of natural adaptogens and various types of adaptation, such as adaptation to dietary restrictions, promotion of physical and mental activity, and adaptation to hypoxia. This review presents data supporting a hypothesis that non-drug activation of self-defense of the body can prevent cognitive decline induced by neurodegenerative processes in the brain by targeting key points of AD pathogenesis.     

RNA isolation from the ribonucleoproteins fixed with formaldehyde

A method for isolating RNA from the polyribosomes and informosomes fixed with formaldehyde was developed. The ribonucleoproteins were obtained by centrifugation in CsCl density gradient. It has been demonstrated that this method makes it possible to obtain full-sized rRNA and mRNA appropriate for molecular hybridization. We succeeded in amplifying 150-nucleotide sequences of individual mRNA and demonstrating the applicability of these RNA preparations for synthesis of labeled probes for RNA arrays. The method proposed is recommended for the search for untranslated mRNA and the study of the changes in translation of individual proteins during early ontogenesis and various pathologies.     

Analysis of <Emphasis Type="Italic">GJB6</Emphasis> (Сx30) and <Emphasis Type="Italic">GJB3</Emphasis> (Сx31) genes in deaf patients with monoallelic mutations in <Emphasis Type="Italic">GJB2</Emphasis> (Сx26) gene in the Sakha Republic (Yakutia)

Тhe DNA testing of autosomal recessive deafness type 1A (DFNB1A, MIM 220290) is complicated when deaf patients have only monoallelic (heterozygous) recessive mutations in the GJB2 (Сх26) gene that is uninformative for establishment of diagnosis. Such patients may be “random” heterozygous carriers of GJB2 mutations as well as have the mutant allele in a cis-regulatory region of GJB2 gene, in element genes encoding other connexins: GJB6 (Сх30) or GJB3 (Сх31). Previous studies of genetic causes of hearing loss in patients from Yakutia were directed to search for only mutations in the GJB2 gene, and the DNA diagnostics was uninformative for 9.7% (38/393) of the patients with monoallelic GJB2 mutations. In this work the search for mutations in genes GJB3 and GJB6 and two deletions с.del(GJB6-D13S1830) and с.del(GJB6-D13S1854) to the cis-regulatory region of GJB2 gene was conducted in 35 patients with GJB2 monoallelic mutations and in 104 normal hearing individuals. The genes studied are two synonymous substitution c.489G>A (р.Leu163Leu) (GJB6) and c.357C>T (р.Asn119Asn) (GJB3) have been found, probably do not have clinical significance, and two nonsynonymous substitution c.301G>A (p.Glu101Lys) (GJB6) and с.580G>A (p.Ala194Thr) (GJB3). Additional experimental evidences are needed for confirmation of pathogenic significance of detected nonsynonymous substitutions in development of hearing loss in studied patients. Diagnosis of the DFNB1A was confirmed in only one patient, who was discovered by the deletion с.del(GJB6-D13S1830) (GJB2) in combination with a recessive mutation с.35delG (GJB2). In general, our results indicate low contribution of mutations in genes GJB6 and GJB3 in hearing loss etiology in Yakutia.     

Participation of heart prostaglandins in cardioprotective cross-effects of adaptation to stress and hypoxia

An adaptation to stress and hypoxia was found to increase the baseline PGE content in the myocardium. The data obtained suggest that the activation of the myocardial system of protective PGs is an important link in the cardioprotective effects of adaptation.     

Cement gland as the adhesion organ in <Emphasis Type="Italic">Xenopus laevis</Emphasis> embryos

The cement gland in batrachians is a temporal ectodermic organ which is necessary for an embryo’s attachment to the substrate. In this review, some notions about the origin of the cement gland of Xenopus laevis frogs, its functioning, genes being expressed in it, and regulation of its formation and development are provided. The role of some homologies of agr genes of the cement gland in Xenopus laevis is noted at different conditions of other animals and man.     

Adaptation to intermittent hypoxia restricts nitric oxide overproduction and prevents beta-amyloid toxicity in rat brain

This study tested the hypothesis that adaptation to intermittent hypoxia (AIH) can prevent overproduction of nitric oxide (NO) in brain and neurodegeneration induced by beta-amyloid (Aβ) toxicity. Rats were injected with a Aβ protein fragment (25–35) into the nucleus basalis magnocellularis. AIH (simulated altitude of 4000 m, 14 days, 4 h daily) was produced prior to the Aβ injection. A passive, shock-avoidance, conditioned response test was used to evaluate memory function. Degenerating neurons were visualized in stained cortical sections. NO production was evaluated in brain tissue by the content of nitrite and nitrate. Expression of nNOS, iNOS, and eNOS was measured in the cortex and the hippocampus using Western blot analysis. 3-Nitrotyrosine formation, a marker of protein nitration, was quantified by slot blot analysis. Aβ injection impaired memory of rats; AIH significantly alleviated this disorder. Histological examination confirmed the protective effect of AIH. Degenerating neurons, which were numerous in the cortex of Aβ-injected, unadapted rats, were essentially absent in the brain of hypoxia-adapted rats. Injections of Aβ resulted in significant increases in NOx and in expression of all NOS isoforms in brain; AIH blunted these increases. NO overproduction was associated with increased amounts of 3-nitrotyrosine in the cortex and hippocampus. AIH alone did not significantly influence tissue 3-nitrotyrosine, but significantly restricted its increase after the Aβ injection. Therefore, AIH affords significant protection against experimental Alzheimer’s disease, and this protection correlates with restricted NO overproduction.     

Transition of Xwnt-11 mRNA from inactive form to polyribosomes in frogs during early embryogenesis

The distribution of Xwnt-11 mRNA between polysomes and informosomes was studied in Xenopus laevis and Rana temporaria during early embryogenesis. The ratio between polysomes and informosomes suggests their involvement in translation of these mRNAs. In eggs and immediately after fertilization the Xwnt-11 mRNAs are mostly positioned in informosomes. During the cleavage stage, these mRNAs have also been recognized in polysomes. Just before the onset of zygote genome functioning (at the stage of mid blastula), Xwnt-11 mRNA rapidly appears in polysomes of Rana embryos. However, in Xenopus, Xwnt-11 mRNA appears in polysomes only at the end of gastrula. Before this stage, the Xwnt-11 mRNA in Xenopus can be found mostly in informosomes.