3H-thymidine and 3H-uridine incorporation into the heart cells of the freshwater crayfish Astacus astacus and the swimming crab Portunus holsatus

DNA and RNA syntheses in the heart cells of two decapod species were investigated with the aid of electron microscopic autoradiography. Isotopes were injected in the cavity of adult animals 4 hours before fixation. 3H-thymidine labeling was found in several satellite cell nuclei and in some particular epicardial cell nuclei. None of myonuclei was labeled. 3H-uridine incorporated in all the nuclei of muscle fibers. Satellite cells were labeled with 3H-uridine very slightly, if at all. Such a peculiarity of biosynthetic processes in the decapod heart satellite cell suggests their myoblastic nature similar to that of satellite cells of somatic muscles. The active 3H-thymidine uptake by the heart satellite cells of adult animals may be accounted for by the permanent growth of the decapods through their whole life span.     

Antigen-specific helper and suppressor activities of T-lymphocytes of the rabbit blood during the development of immunologic response to heterologous erythrocytes

A titre of hemolysins in blood serum, helper and suppressor activity of blood T-lymphocytes in response of ++blast transformation to Con A in different doses (8 and 60 ml) and was determined in rabbits after single and two-fold (with an interval of 30 days) immunization of the ram erythrocytes. Examinations were conducted 2, 9, 16 and 30 days after antigen introduction. Peculiarities of changes in antigen-specific helper and suppressor activity of lymphocytes and their balance in dynamics of primary and secondary immune responses are determined.     

The discovery of Hsp70 domain with cell-penetrating activity

Chaperone Hsp70 can cross the plasma membrane of living cells using mechanisms that so far have not received much research attention. Searching the part of the molecule that is responsible for transport ability of Hsp70, we found a cationic sequence composed of 20 amino acid residues on its surface, KST peptide, which was used in further experiments. We showed that KST peptide enters living cells of various origins with the same efficiency as the full-length chaperone. KST peptide is capable of carrying cargo with a molecular weight 30 times greater than its own into cells. When we compared the membrane-crossing activity of KST peptide in complex with Avidin (KST–Av complex) with that of similarly linked canonical TAT peptide, we found that TAT peptide penetrated SK-N-SH human neuroblastoma cells at a similar rate and efficiency as the KST peptide. Furthermore, KST peptide can carry protein complexes consisting of a specific antibody coupled to the peptide through the Avidin bridge. An antibody to Hsp70 delivered to SK-N-SH cells with high expression level of Hsp70 reduced the protective power of the chaperone and sensitized the cells to the pro-apoptotic effect of staurosporine. We studied the mechanisms of penetration of KST–Av and full-length Hsp70 inside human neuroblastoma SK-N-SH and human erythroleukemia K-562 cells and found that both used an active intracellular transport mechanism that included vesicular structures and negatively charged lipid membrane domains. Competition analysis of intracellular transport showed that the chaperone reduced intracellular penetration of KST peptide and conversely KST peptide prevented Hsp70 transport in a dose-dependent manner.

Electronic supplementary material

The online version of this article (doi:10.1007/s12192-014-0554-z) contains supplementary material, which is available to authorized users.     

Pesticide exposure: the hormonal function of the female reproductive system disrupted?

Some pesticides may interfere with the female hormonal function, which may lead to negative effects on the reproductive system through disruption of the hormonal balance necessary for proper functioning. Previous studies primarily focused on interference with the estrogen and/or androgen receptor, but the hormonal function may be disrupted in many more ways through pesticide exposure. The aim of this review is to give an overview of the various ways in which pesticides may disrupt the hormonal function of the female reproductive system and in particular the ovarian cycle. Disruption can occur in all stages of hormonal regulation: 1. hormone synthesis; 2. hormone release and storage; 3. hormone transport and clearance; 4. hormone receptor recognition and binding; 5. hormone postreceptor activation; 6. the thyroid function; and 7. the central nervous system. These mechanisms are described for effects of pesticide exposure in vitro and on experimental animals in vivo. For the latter, potential effects of endocrine disrupting pesticides on the female reproductive system, i.e. modulation of hormone concentrations, ovarian cycle irregularities, and impaired fertility, are also reviewed. In epidemiological studies, exposure to pesticides has been associated with menstrual cycle disturbances, reduced fertility, prolonged time-to-pregnancy, spontaneous abortion, stillbirths, and developmental defects, which may or may not be due to disruption of the female hormonal function. Because pesticides comprise a large number of distinct substances with dissimilar structures and diverse toxicity, it is most likely that several of the above-mentioned mechanisms are involved in the pathophysiological pathways explaining the role of pesticide exposure in ovarian cycle disturbances, ultimately leading to fertility problems and other reproductive effects. In future research, information on the ways in which pesticides may disrupt the hormonal function as described in this review, can be used to generate specific hypotheses for studies on the effects of pesticides on the ovarian cycle, both in toxicological and epidemiological settings.     

Interaction of gangliosides with low-density proteins from human blood

Gangliosides have been shown to modulate the receptor-mediated endocytosis of low density lipoproteins (LDL). The direct interaction of LDL with various gangliosides has been studied. Binding of gangliosides to LDL immobilized on CNBr-Sepharose (LDL-Sepharose) and the influence of gangliosides on the fluorescence of LDL containing anthrylvinyl-labeled sphingomyelin were investigated. The binding of 3H-gangliosides to LDL-Sepharose, as well as fluorescence polarization of LDL were found to depend on the structure and concentration of the gangliosides in a specific saturable manner. The data obtained indicate that gangliosides interact with apolipoprotein B via specific binding sites.     

Different modes of ozone-induced lipid oxidation in Candida utilis yeast cells and isolated membrane preparations

Significant differences in the development of ozonolysis of lipids in membrane preparations and intact cells of the Candida utilis yeast were revealed. First, unlike isolated membranes, in which lipid modifications can be initiated by low ozone doses (< 0.5 micromol O3/mg protein) and develop proportionally to the treatment dose, in intact yeast cells, even the most ozone-sensitive sterols and nitrogen-containing phospholipids (phosphatidylcholine and phosphatidylethanolamine) did not undergo oxidative destruction at doses up to 6.0 micromol O3/mg protein. Second, the peculiarity of the ozone-initiated lipid modification in intact cells was that different classes of lipids exhibited different sensitivity to ozone. With an increase in the ozone dose, neutral lipids (sterols) and nitrogen-containing phospholipids (phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) were modified to a greater extent. Third, the accumulation of lipid peroxidation products upon ozone treatment of cells, in contrast to the isolated membranes, was absent at low ozone doses and was recorded only after the lethal damage. It is suggested that these differences are related to both the function of antioxidative enzymes (catalase, superoxide dismutase, peroxidase, etc.) and the difference between the structural states (i.e., stability and accessibility to oxidation) of lipids in the isolated membranes and the intact cells.     

Investigation of oxosubstances in plant leaf lipids

Surface lipids of plant leaves of different groups were investigated by spectral, chromatographic and functional analysis methods. Absence of oxosubstances in surface lipids of coniferous and their characteristics in tropical species were shown. Functions of oxosubstances are discussed.     

Photoconversion of the Chromophore of a Fluorescent Protein from Dendronephthya sp.

A green fluorescent protein from the coral Dendronephthya sp. (Dend FP) is characterized by an irreversible light-dependent conversion to a red-emitting form. The molecular basis of this phenomenon was studied in the present work. Upon UV-irradiation at 366 nm, the absorption maximum of the protein shifted from 494 nm (the green form) to 557 nm (the red form). Concurrently, in the fluorescence spectra the emission maximum shifted from 508 to 575 nm. The green form of native Dend FP was shown to be a dimer, and the oligomerization state of the protein did not change during its conversion to the red form. By contrast, UV-irradiation caused significant intramolecular changes. Unlike the green form, which migrates in SDS-polyacrylamide gels as a single band corresponding to a full-length 28-kD protein, the red form of Dend FP migrated as two fragments of 18- and 10-kD. To determine the chemical basis of these events, the denatured red form of Dend FP was subjected to proteolysis with trypsin. From the resulting hydrolyzate, a chromophore-containing peptide was isolated by HPLC. The structure of the chromophore from the Dend FP red form was established by methods of ESI, tandem mass spectrometry (ESI/MS/MS), and NMR-spectroscopy. The findings suggest that the light-dependent conversion of Dend FP is caused by generation of an additional double bond in the side chain of His65 and a resulting extension of the conjugated system of the green form chromophore. Thus, classified by the chromophore structure, Dend FP should be referred to the Kaede subfamily of GFP-like proteins.