Salicylic acid and jasmonic acid biosynthetic pathways are simultaneously activated in transgenic Arabidopsis expressing the rolB/C gene from Ipomoea batatas.

The Agrobacterium rhizogenes root oncogenic locus (rol) genes interfere with hormone balance by altering their synthesis and/or recognition, giving rise to varied impacts on the physiological characteristics of plants and cell cultures. The homolog of the rolB and rolC genes from Ipomoea batatas, named Ib-rolB/C, similarly induces morphological and physiological alterations in transgenic Arabidopsis thaliana; however, its role in plant hormonal homeostasis has not been previously defined. In this study, we found that external application of salicylic acid (SA) and methyl jasmonate (MeJA) significantly upregulated Ib-rolB/C in detached I. batatas leaves. Furthermore, heterologous expression of Ib-rolB/C in A. thaliana markedly enhanced the accumulation of SA and MeJA, and to a lesser extent, elevated abscisic acid (ABA) levels, through the modulation of genes specific to hormone biosynthesis. Even though the RolB/RolC homolog protein has a notable structural resemblance to the RolB protein from A. rhizogenes, it exhibits a distinct localization pattern, predominantly residing in the cytoplasm and certain discrete subcellular structures, instead of the nucleus. Consequently, the functions of RolB/RolC in both naturally and artificially transgenic plants are linked to changes in the hormonal state of the cells, though the underlying signaling pathways remain to be elucidated.

Interaction of Telomeric Retroelement HeT-A Transcripts and Their Protein Product Gag in Early Embryogenesis of Drosophila.

The telomere is a nucleoprotein complex at the ends of linear chromosomes that protects them from fusion and degradation. The telomere consists of telomeric DNA, a protective protein complex and telomeric RNA. Biogenesis of telomeric transcripts in development is still far from being understood. Drosophila telomeres are elongated by a transposition of specialized telomeric retrotransposons that encode proteins. Using transgenic constructs encoding tagged telomeric protein, we found that transcripts of Drosophila telomeric element HeT-A bind Gag-HeT-A protein encoded by these transcripts. Maternal HeT-A transcripts and Gag-HeT-A form ribonucleoprotein granules around centrosomes, centers of microtubule organization, during blastoderm formation, upon disruption of telomere silencing during oogenesis. The specific localization of HeT-A RNA is dependent on microtubules since disruption of microtubules caused delocalization of HeT-A transcripts. This transgenic system is a valuable model for the study of telomeric RNA biogenesis.

[Cytological analysis of the reaction of the nucleolar RNA and RNA-binding proteins to oxidative stress in HeLa cells].

The organization and functional activity of the nucleoli of mammalian cells can be modified in response to various stress factors. However, data on the reaction of nucleoli to oxidative stress remain limited. In this paper, we have studied the localization of nucleolar RNAs and two RNA-binding proteins--fibrillarin, a pre-rRNA processing factor, and nucleophosmin/B23, a pre-ribosome assembly factor, in HeLa cells exposed to 1 mM H2O2 up to four hours. We have shown that under the conditions used H2O2 does not induce death, but inhibits rDNA transcription, reduces the total RNA content in the cells and the amount of 18S rRNA in the nucleoli, and causes relocalization of fibrillarin and nucleophosmin/B23 to the nucleoplasm. To date, similar changes in the localization of fibrillarin were described in mammalian cells only after HgCl2 treatment. Redistribution of nucleophosmin/B23 observed in H2O2-treated cells occurred in mammalian cells under inhibition of rDNA transcription and early rRNA processing. Overall, this study shows the high sensitivity of the nucleoli of HeLa cells to acute oxidative stress, which is clearly evident on the cytological level.

[Parameters which affect the estimation of protein mobility by method FRAP in living cells on the example of protein fibrillarin].

Method FRAP (fluorescence recovery after photobleaching) in combination with confocal laser scanning microscopy represents one of the principal approaches in studying the properties of proteins in living mammal cells. However, the data of different authors on the dynamic properties of the same protein and even in cells of the same type can differ greatly. The reasons of such discrepancies were not specifically analyzed yet. In the present work, on the example of the nucleolar protein fibrillarin fused to EGFP, was studied the impact of area of the region of interest (ROI) and temperature conditions on the main dynamic characteristics of the protein, such as mobile fraction and time for half-time of fluorescence recovery after photobleaching (t1/2). Obtained results suggest that both parameters have a great impact on the estimation of mobile properties of fibrillarin-EGFP in HeLa cells. Was concluded that during FRAP experiments the area of ROI has to be standardized and, as possible, minimized. Moreover, analyzing the dynamic properties of the nucleolar proteins, which take part in the temperature-sensitive reactions, the standard temperature conditions should also be standardized.

[Structural changes in the endothelium of the major arteries under conditions of longitudinal stretching in vivo (based on scanning electron microscopic data)]. / Izmenenie struktury éndoteliia magistral'nykh arterii v usloviiakh prodol'nogo rastiazheniia in vivo (po dannym skaniruiushchei élektronnoi mikroskopii).

The method of scanning electron microscopy was used for studying three-dimensional organization of the endothelium of major vessels under conditions of distraction in vivo. The distraction resulted in an enlargement of the spaces between endotheliocytes without formation of considerable areas of deendothelialized surface. The main mechanism of induction of flattening and division of endotheliocytes in the zone of distraction seems to be the elimination of the contact inhibition resulting from a mechanical distraction.