Actinobacteria Isolated from an Underground Lake and Moonmilk Speleothem from the Biggest Conglomeratic Karstic Cave in Siberia as Sources of Novel Biologically Active Compounds

Actinobacteria isolated from unstudied ecosystems are one of the most interesting and promising sources of novel biologically active compounds. Cave ecosystems are unusual and rarely studied. Here, we report the isolation and characterization of ten new actinobacteria strains isolated from an ancient underground lake and moonmilk speleothem from the biggest conglomeratic karstic cave in Siberia with a focus on the biological activity of the obtained strains and the metabolite dereplication of one active strain. Streptomyces genera isolates from moonmilk speleothem demonstrated antibacterial and antifungal activities. Some of the strains were able to inhibit the growth of pathogenic Candida albicans.     

Protein kinase C phosphorylates ribosomal protein S6 kinase betaII and regulates its subcellular localization

The ribosomal protein S6 kinase (S6K) belongs to the AGC family of Ser/Thr kinases and is known to be involved in the regulation of protein synthesis and the G(1)/S transition of the cell cycle. There are two forms of S6K, termed S6Kalpha and S6Kbeta, which have cytoplasmic and nuclear splice variants. Nucleocytoplasmic shuttling has been recently proposed for S6Kalpha, based on the use of the nuclear export inhibitor, leptomycin B. However, the molecular mechanisms regulating subcellular localization of S6Ks in response to mitogenic stimuli remain to be elucidated. Here we present data on the in vitro and in vivo phosphorylation of S6Kbeta, but not S6Kalpha, by protein kinase C (PKC). The site of phosphorylation was identified as S486, which is located within the C-terminal nuclear localization signal. Mutational analysis and the use of phosphospecific antibodies provided evidence that PKC-mediated phosphorylation at S486 does not affect S6K activity but eliminates the function of its nuclear localization signal and causes retention of an activated form of the kinase in the cytoplasm. Taken together, this study uncovers a novel mechanism for the regulation of nucleocytoplasmic shuttling of S6KbetaII by PKC-mediated phosphorylation.     

Lipid and fatty acid composition of scavenging amphipods Ommatogammarus spp. from different depths of lake Baikal

Limnology - The lipid and fatty acid content of benthopelagic scavenging amphipods Ommatogammarus flavus and O. albinus from different depths of Lake Baikal were studied. These amphipods, known to...     

Expression patterns and organization of the hsp70 genes correlate with thermotolerance in two congener endemic amphipod species (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal

We studied various aspects of heat‐shock response with special emphasis on the expression of heat‐shock protein 70 (hsp70) genes at various levels in two congener species of littoral endemic amphipods (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal which show striking differences in their vertical distribution and thermal tolerance. Although both the species studied demonstrate high constitutive levels of Hsp70, the thermotolerant E. cyaneus exhibited a 5‐fold higher basal level of Hsp70 proteins under normal physiological conditions (7 °C) and significantly lower induction of Hsp70 after temperature elevation compared with the more thermosensitive E. verrucosus. We isolated the hsp70 genes from both species and analysed their sequences. Two isoforms of the cytosolic Hsp70/Hsc70 proteins were detected in both species under normal physiological conditions and encoded by two distinct hsp/hsc70 family members. While both Hsp70 isoforms were synthesized without heat shock, only one of them was induced by temperature elevation. The observed differences in the Hsp70 expression patterns, including the dynamics of Hsp70 synthesis and threshold of induction, suggest that the increased thermotolerance in E. cyaneus (compared with E. verrucosus) is associated with a complex structural and functional rearrangement of the hsp70 gene family and favoured the involvement of Hsp70 in adaptation to fluctuating thermal conditions. This study provides insights into the molecular mechanisms underlying the thermal adaptation of Baikal amphipods and represents the first report describing the structure and function of the hsp70 genes of endemic Baikal species dwelling in thermally contrasting habitats.     

Identification of paxilin domains interacting with β-catenin

Barrier-protective agonists induce association of focal adhesions (FA) and adherens junctions (AJ) in endothelial cells. Here we identified specific domains of FA protein paxillin interacting with AJ protein and examined regulation of paxillin domain interactions with β-catenin by Rac GTPase. Co-expression of paxillin LD-1,2; LD-3,4; LIM-1,2; and LIM-3,4 domains with β-catenin showed exclusive interaction of LIM-1,2 and LIM-3,4 with β-catenin, which was enhanced by agonist-induced Rac activation or expression of activated Rac mutant. These results demonstrate a novel function of paxillin LIM domains in targeting β-catenin in a Rac-dependent manner, which may play a role in Rac-dependent control of FA-AJ interactions and monolayer integrity.     

Panel of SEREX-defined antigens for breast cancer autoantibodies profile detection

Content: Identification of panel of SEREX-defined antigens for breast cancer autoantibodies profile detection.

Objective: To create panel of antigens that can differentiate breast cancer patients and healthy individuals.

Methods: SEREX (serological analysis of cDNA expression libraries) method, ELISA (enzyme-linked immunosorbent assay), qPCR (quantitative polymerase chain reaction).

Results: In large-scale screening of 16 SEREX-antigens by sera of breast cancer patients and healthy donors, a combination of six antigens (RAD50, PARD3, SPP1, SAP30BP, NY-BR-62 and NY-CO-58) was identified, which can differentiate breast cancer patients and healthy donors with 70% sensitivity and 91% specificity. Elevated mRNA expression of SPP1 gene was revealed in breast tumors (2–7-fold) that correlated with SPP1 antigen immunoreactivity in autologous patients’ sera.

Conclusions: The new panel of six SEREX-antigens was proposed, which enables creation of serological assay for breast cancer diagnostics and/or prognosis.     

Hepatic Gene Expression Changes in Rats Internally Exposed to Radioactive 56MnO2 Particles at Low Doses

We have studied the biological effects of the internal exposure to radioactive manganese-56 dioxide (⁵⁶MnO₂), the major radioisotope dust found in soil after atomic bomb explosions. Our previous study of blood chemistry indicated a possible adverse effect of ⁵⁶MnO₂ on the liver. In the present study, we further examined the effects on the liver by determining changes in hepatic gene expressions. Male Wistar rats were exposed to ⁵⁶MnO₂ particles (three groups with the whole-body doses of 41, 90, and 100 mGy), stable MnO₂ particles, or external ⁶⁰Co γ-rays (2 Gy), and were examined together with the non-treated control group on postexposure day 3 and day 61. No histopathological changes were observed in the liver. The mRNA expression of a p53-related gene, the cyclin-dependent kinase inhibitor 1A, increased in ⁵⁶MnO₂ as well as in γ-ray irradiated groups on postexposure day 3 and day 61. The expression of a stress-responsive gene, nuclear factor κB, was also increased by ⁵⁶MnO₂ and γ-rays on postexposure day 3. However, the expression of cytokine genes (interleukin-6 or chemokine ligand 2) or fibrosis-related TGF-β/Smad genes (Tgfb1, Smad3, or Smad4) was not altered by the exposure. Our data demonstrated that the internal exposure to ⁵⁶MnO₂ particles at less than 0.1 Gy significantly affected the short-term gene expressions in the liver in a similar manner with 2 Gy of external γ-irradiation. These changes may be adaptive responses because no changes occurred in cytokine or TGF-β/Smad gene expressions.     

Peptide design of a competitive inhibitor for HMG-CoA reductase based on statin structure

This study investigates a proposed design of a peptide sequence that is based on a bioactive conformation of statins that act as the competitive inhibitors of HMG-CoA for HMGR. To bridge these heterogeneous organic compounds, a conformational aspect relating to an analysis of the flexibility of the peptide molecules and their occupied volumes was applied to the peptide design. The design criterion was formulated in terms of a proximity parameter (Pr), reflecting the probability of an active peptide conformation to approximate the statin. Through a structure-functional analysis of previously synthesized peptides and statin molecules, nine peptides were selected for the peptide library. Comparing the calculated proximity parameters, four peptides (IAVE, YAVE, IVAE, and YVAE) from the library were selected and synthesized. In vitro assays elucidated the inhibition properties for HMGR that are exhibited by these peptides. Among all peptides, YVAE showed the highest ability to inhibit HMGR. A kinetic analysis revealed that this peptide is a competitive inhibitor of HMG-CoA with an equilibrium constant of inhibitor binding (K(i)) of 15.2 +/- 1.4 microM. The calculated coefficient correlation (R) between log (IC(50)) and the inverse value of proximity parameter (1/Pr) was found to be 0.99, indicating a high degree of correlation and efficacy of the given approach in the peptide sequence design.