Dominant mutations of rifampicin resistance in Escherichia coli K-12

Significant portion (up to 20%) of dominant mutations (rifd mutations) was observed among spontaneous mutations of rifampicin resistance picked up in cells of haploid Escherichia coli strain. These mutations are similar to rifd mutations obtained earlier when selecting them in rif-s/rif-s merodiploids. On the basis of analysis of nucleotide substitutions taking place in formation of spontaneous and induced mutations, it is established that rifd mutations are caused by single nucleotide substitution. The majority of rifd mutations are localized in a small region of the central part of RNA polymerase beta-subunit gene covering less than 200 base pairs. A rifd mutant has been described which occurred as a result of micro-deletion in one of the "hot" spots of the central region of beta-subunit gene.     

A comparative evaluation of the changes in the duration of "hexenal sleep" in acute radiation and combined radiation-thermal lesions]

In experiments with Wistar rats it was found that the increase in the length of the "hexenal dream" during the first week after the effect of a mixture of radiation and heat is much more pronounced than that observed after exposure to radiation alone and independent of the severity of a radiation component (gamma radiation, 4, 6 and 7.5 Gy). The peculiarities revealed in the hypnotic effect of hexenal develop against the background of the postirradiation aggravation of hypoalbuminemia and decrease in the liver ATP.     

Study of the microcirculatory bed by a method of demonstrating lactate dehydrogenase]

The method of detection of lactate dehydrogenase with some modification was used to study the microcirculatory bed in total preparations of serous membranes and plane sections of organs of any square surface. The employment of non-fixed material, the short time (from 15 to 60 min) necessary to obtain preparations of any size and simultaneous determination of the localization and the degree of the activity of the enzyme--are, to the authors opinion, undoubtful advantages of the given method, which can be an addition to the well-known impregnation method of determination of the microcirculatory bed.     

Mathematical modeling of the invagination of epithelial layers in embryogenesis

Biophysics - Invagination of epithelial sheets is an important type of morphogenetic deformation. Primary invagination during gastrulation in the sea urchin provides one of the simplest and...     

Non-canonical functions of the cellular transporter P-glycoprotein

P-glycoprotein/ABCB1 (Pgp) is a well known protein of cell defense system. It is localized in cell membrane and pumps different drugs out of various cells using ATP energy. Its overexpression is associated with the development of multidrug resistance (MDR) in cancer cells. The data showing that Pgp also has other functions appeared recently, and this review surveys these data. In particular, (1) Pgp can protect cells from apoptosis; it suppresses the expression of endogenous protein TRAIL and decreases the activity of caspases 8 and 3; (2) Pgp is able to act as an outwardly directed flippase; (3) Pgp participates in a proper development of the innate immune response to intracellular pathogens and in the development of inflammation; (4) functionally active Pgp can be transferred from drug-resistant to drug-sensitive cells by microvesicles (MV). This is a new way of the Pgp-mediated MDR emergence in populations of tumor cells. Thus, Pgp functions as a regulator of some cellular processes. Molecular mechanisms of the Pgp influence on tumor cell viability are related not only with the drug efflux but also with some other functions.     

Properties of stem cells isolated from subcutaneous and subepicardial adipose tissues

Stem cells (SCs) vary in morphological, immunophenotypic, proliferative, and differentiation characteristics depending on their tissue source. Comparative analysis of their biological properties is essential for making an optimal SC choice for regenerative therapy. Using immunocytochemistry, flow cytometry, histochemistry, and RT-PCR, we have investigated SCs obtained from human subepicardial (SEC-AT) and subcutaneous (SC-AT) adipose tissues and cultured under similar conditions without any differentiation-promoting factors. The cultures were similar in having a high proportion of proliferating cells positive for nuclear antigen (PCNA). In both cultures, immunophenotyping has revealed high expression of mesenchymal stem-cell surface markers CD29, CD44, CD73, and CD105; low expression of CD31, CD34, and CD45; and variability in CD117, CD146, and CD309 expression. The only difference in the CD marker profile was the significantly lower expression of CD90 in the culture of SCs from SC-AT than from SEC-AT. Histochemical analysis showed a lack of Oil Red O-positive cells in both cultures and an about ten times higher number of alkaline phosphatase-positive cells among SCs from SC-AT. In both cultures, immunocytochemistry detected low expression of the slow myosin heavy chain marker MAB1628 and smooth muscle actin marker α-hSMA. Expression of the gap junction protein connexin-43 was markedly higher in cells from SC-AT cultures. Only the cells of these cultures expressed the epithelial cell marker cytokeratin-19. GATA4 mRNA expression detected with RT-PCR was identified in SEC-AT rather than in SC-AT cells. Our results suggest that SC-AT is enriched compared to SEC-AT with epithelial cell and osteogenic progenitors. In turn, SEC-AT possesses cardiomyogenic SCs and can be considered an alternative source for cell cardiotherapy.     

Sex differences in the gonadotropins of the Black Sea plaice Scophthalmus maeoticus

No quantitative differences in the effect of acetone-dried pituitaries from male and female plaice upon loach-recipients (Misgurnus fossilis) have been found in testing the activity of the glands on plaice-recipients. This fact suggests the existence of qualitative differences between gonadotropins from plaice males and females. This conclusion was supported in the experiments on the effect of purified gonadotropic fractions, isolated separately from male and female hypophyses, on maturation of the loach. Three gonadotropic fractions obtained by preparative disc-electrophoresis in polyacrylamide gel, differ in their biological activity and electrophoretic mobility. The activity of gonadotropic fractions in males is higher, than in females; electrophoretic mobility of two fractions is also higher in males, whereas the third fraction does not exhibit sexual differences.     

Glycan-binding profile of DC-like cells

Modification of vaccine carriers by decoration with glycans can enhance binding to and even targeting of dendritic cells (DCs), thus augmenting vaccine efficacy. To find a specific glycan-“vector” it is necessary to know glycan-binding profile of DCs. This task is not trivial; the small number of circulating blood DCs available for isolation hinders screening and therefore advancement of the profiling. It would be more convenient to employ long-term cell cultures or even primary DCs from murine blood. We therefore examined whether THP-1 (human monocyte cell line) and DC2.4 (immature murine DC-like cell line) could serve as a model for human DCs. These cells were probed with a set of glycans previously identified as binding to circulating human CD14low/-CD16+CD83+ DCs. In addition, we tested a subpopulation of murine CD14low/-CD80+СD11c+CD16+ cells reported as relating to the human CD14low/-CD16+CD83+ cells. Manα1–3(Manα1–6)Manβ1–4GlcNAcβ1–4GlcNAcβ bound to both the cell lines and the murine CD14low/-CD80+СD11c+CD16+ cells. Primary cells, but not the cell cultures, were capable of binding GalNAcα1–3Galβ (Adi), the most potent ligand for binding to human circulating DCs. In conclusion, not one of the studied cell lines proved an adequate model for DCs processes involving lectin binding. Although the glycan-binding profile of BYRB-Rb (8.17)1Iem mouse DCs could prove useful for assessing human DCs, important glycan interactions were missing, a situation which was aggravated when employing cells from the BALB/c strain. Accordingly, one must treat results from murine work with caution when seeking vaccine targeting of human DCs, and certainly should avoid cell lines such as THP-1 and DC2.4 cells.     

Connection between proliferation rate and temozolomide sensitivity of primary glioblastoma cell culture and expression of <Emphasis Type="Italic">YB-1</Emphasis> and <Emphasis Type="Italic">LRP/MVP</Emphasis>

Glioblastomas (GBL) are the most common and aggressive brain tumors. They are distinguished by high resistance to radiation and chemotherapy. To find novel approaches for GBL classification, we obtained 16 primary GBL cell cultures and tested them with real-time PCR for mRNA expression of several genes (YB-1, MGMT, MELK, MVP, MDR1, BCRP) involved in controlling cell proliferation and drug resistance. The primary GBL cultures differed in terms of proliferation rate, wherein a group of GBL cell cultures with low proliferation rate demonstrated higher resistance to temozolomide. We found that GBL primary cell cultures characterized by high proliferation rate and lower resistance to temozolomide expressed higher mRNA level of the YB-1 and MDR1 genes, whereas upregulated expression of MVP/LRP mRNA was a marker in the group of GBL with low proliferation rate and high resistance. A moderate correlation between expression of YB-1 and MELK as well as YB-1 and MDR1 was found. In the case of YB-1 and MGMT expression, no correlation was found. A significant negative correlation was revealed between mRNA expression of MVP/LRP and MELK, MDR1, and BCRP. No correlation in expression of YB-1 and MVP/LRP genes was observed. It seems that mRNA expression of YB-1 and MVP/LRP may serve as a marker for GBL cell cultures belonging to distinct groups, each of which is characterized by a unique pattern of gene activity.