The role of germinal vesicle in maturation of Pleurodeles waltlii oocytes induced by steroids

The maturation of oocytes from unstimulated Pleurodeles waltlii females can be induced in vitro. All full-grown oocytes covered by follicular envelopes mature under the influence of progesterone, testosterone, and a synthetic steroid (CDMT). Enucleation of oocytes prior to maturation induction resulted in a significantly lower percentage of maturation. Irradiation, or the treatment of oocytes with actinomycin D, did not affect their maturation. Therefore the lower percentage of maturation after enucleation must be due to the lack of karyoplasm. Karyoplasm appears to be necessary for the production of the maturation-promoting factor in P. waltlii oocytes.     

Investigation of protective properties of Shigella sonnei carbohydrate biopolymers under experimental endotoxic shock models

We studied tolerogenic properties of new nonpyrogenic low-endotoxic complex preparation composed of Shigella sonnei carbohydrate biopolymers under D-galactosamine and direct experimental endotoxic shock models. Pretreatment with complex preparation (exopolysaccharide + lipopolysaccharide) S. sonnei protects mice (CBA × C57B1/6)F1 against lipopolysaccharide (E. coli O:55)-mediated death. We demonstrate correlation between increasing preimmunization dose of complex preparation with rate of survival and reduction of TNF-α serum level under a direct endotoxic shock model.     

Bacterial structures and ecosystem functions in glaciated floodplains: contemporary states and potential future shifts

Glaciated alpine floodplains are responding quickly to climate change through shrinking ice masses. Given the expected future changes in their physicochemical environment, we anticipated variable shifts in structure and ecosystem functioning of hyporheic microbial communities in proglacial alpine streams, depending on present community characteristics and landscape structures. We examined microbial structure and functioning during different hydrologic periods in glacial (kryal) streams and, as contrasting systems, groundwater-fed (krenal) streams. Three catchments were chosen to cover an array of landscape features, including interconnected lakes, differences in local geology and degree of deglaciation. Community structure was assessed by automated ribosomal intergenic spacer analysis and microbial function by potential enzyme activities. We found each catchment to contain a distinct bacterial community structure and different degrees of separation in structure and functioning that were linked to the physicochemical properties of the waters within each catchment. Bacterial communities showed high functional plasticity, although achieved by different strategies in each system. Typical kryal communities showed a strong linkage of structure and function that indicated a major prevalence of specialists, whereas krenal sediments were dominated by generalists. With the rapid retreat of glaciers and therefore altered ecohydrological characteristics, lotic microbial structure and functioning are likely to change substantially in proglacial floodplains in the future. The trajectory of these changes will vary depending on contemporary bacterial community characteristics and landscape structures that ultimately determine the sustainability of ecosystem functioning.     

“Suppressor factor” of neutrophils: A short story of a long-term misconception

A large body of evidence obtained during the last decade has demonstrated that neutrophils suppress T cell proliferation in different models of inflammation and cell interaction. The commonly used method for assessing cell proliferation and proliferation inhibition is measuring [³H]thymidine incorporation into cells. Earlier, we observed inhibition of [³H]thymidine uptake in experiments on neutrophil-mediated regulation of T cell response in tuberculosis immunity. Here, we used different types of proliferating cells to analyze the nature of the soluble “neutrophil factor” by a variety of methods (dialysis, HPLC, mass spectrometry, and NMR) and unambiguously demonstrated that neutrophils do not synthesize a specific factor inhibiting cell proliferation, but secrete high concentrations of extracellular thymidine that competitively inhibit [³H]thymidine incorporation. Although the physiological significance of thymidine secretion by neutrophils remains unknown, this phenomenon should be carefully considered when designing test systems for studying cell–cell interactions.     

Rating of perceived exertion as a tool for prescribing and self regulating interval training: a pilot study

The aim of the present study was to analyse the usefulness of the 6-20 rating of perceived exertion (RPE) scale for prescribing and self-regulating high-intensity interval training (HIT) in young individuals. Eight healthy young subjects (age = 27.5±6.7 years) performed maximal graded exercise testing to determine their maximal and reserve heart rate (HR). Subjects then performed two HIT sessions (20 min on a treadmill) prescribed and regulated by their HR (HR: 1 min at 50% alternated with 1 min at 85% of reserve HR) or RPE (RPE: 1 minute at the 9-11 level [very light-fairly light] alternated with 1 minute at the 15-17 level [hard-very hard]) in random order. HR response and walking/running speed during the 20 min of exercise were compared between sessions. No significant difference between sessions was observed in HR during low- (HR: 135±15 bpm; RPE: 138±20 bpm) and high-intensity intervals (HR: 168±15 bpm; RPE: 170±18 bpm). Walking/running speed during low- (HR: 5.7±1.2 km · h⁻¹; RPE: 5.7±1.3 km · h⁻¹) and high-intensity intervals (HR: 7.8±1.9 km · h⁻¹; RPE: 8.2±1.7 km · h⁻¹) was also not different between sessions. No significant differences were observed in HR response and walking/running speed between HIT sessions prescribed and regulated by HR or RPE. This finding suggests that the 6-20 RPE scale may be a useful tool for prescribing and self-regulating HIT in young subjects.     

Role of nonstructural protein NS2A in flavivirus assembly

Flavivirus nonstructural (NS) proteins are involved in RNA replication and modulation of the host antiviral response; however, evidence is mounting that some NS proteins also have essential roles in virus assembly. Kunjin virus (KUN) NS2A is a small, hydrophobic, transmembrane protein that is part of the replication complex and inhibits interferon induction. Previously, we have shown that an isoleucine (I)-to-asparagine (N) substitution at position 59 of the NS2A protein blocked the production of secreted virus particles in cells electroporated with viral RNA carrying this mutation. We now show that prolonged incubation of mutant KUN NS2A-I59N replicon RNA, in an inducible BHK-derived packaging cell line (expressing KUN structural proteins C, prM, and E), generated escape mutants that rescued the secretion of infectious virus-like particles. Sequencing identified three groups of revertants that included (i) reversions to wild-type, hydrophobic Ile, (ii) pseudorevertants to more hydrophobic residues (Ser, Thr, and Tyr) at codon 59, and (iii) pseudorevertants retaining Asn at NS2A codon 59 but containing a compensatory mutation (Thr-to-Pro) at NS2A codon 149. Engineering hydrophobic residues at NS2A position 59 or the compensatory T149P mutation into NS2A-I59N replicon RNA restored the assembly of secreted virus-like particles in packaging cells. T149P mutation also rescued virus production when introduced into the full-length KUN RNA containing an NS2A-I59N mutation. Immunofluorescence and electron microscopy analyses of NS2A-I59N replicon-expressing cells showed a distinct lack of virus-induced membranes normally present in cells expressing wild-type replicon RNA. The compensatory mutation NS2A-T149P restored the induction of membrane structures to a level similar to those observed during wild-type replication. The results further confirm the role of NS2A in virus assembly, demonstrate the importance of hydrophobic residues at codon 59 in this process, implicate the involvement of NS2A in the biogenesis of virus-induced membranes, and suggest a vital role for the virus-induced membranes in virus assembly.     

Differential expression of an ensemble of the key genes involved in cell-cycle regulation in lung cancer

Targeted cancer therapy directed at individual targets is often accompanied by the rapid development of drug resistance. The development of a new generation of antitumor drugs involves the search for many targets simultaneously to block or, conversely, restore their activity. In this regard, simultaneous analysis of gene expression in a complex network of interactions, primarily cell cycle control elements, is relevant for the search of specific molecular markers for the differential diagnosis of adenocarcinoma (ADC) and squamous cell lung cancer (SCC), as well as new targets for therapy. In this paper we performed an extended quantitative analysis of the expression of two suppressor genes, CTDSPL and its target RB1, as well as 84 genes of the main participants of the p16^INK4A-Cdk/cyclin D1-Rb and p53/p21^Waf1 signaling pathways in the histological types of non-small-cell lung cancer (NSCLC), i.e., ADC and SCC, using the special panel of the Human Cell Cycle Regulation Panel. The expression profile of some genes shows the specificity to the histological type of NSCLC and the presence of metastases. The genes with a significantly increased expression that affect the activity of Rb (cyclins, cyclin-dependent kinases, their activators, inhibitors, etc.) can serve as potential targets for combined therapy of both ADC and SCC.     

Comparative analysis of T lymphocytes recovered from the lungs of mice genetically susceptible, resistant, and hyperresistant to Mycobacterium tuberculosis-triggered disease

Genetic control of susceptibility to tuberculosis (TB) is being intensively studied, and immune responses to mycobacteria are considerably well characterized. However, it remains largely unknown which parameters of response distinguish resistant and susceptible TB phenotypes. Mice of I/St and A/Sn inbred strains and (A/Sn x I/St)F(1) hybrids were previously categorized as, respectively, susceptible, resistant, and hyperresistant to Mycobacterium tuberculosis-triggered disease. In the present work we compared parameters of lung T cell activation and response following M. tuberculosis challenge. In all mice, the disease progression was accompanied by a marked accumulation in the lungs of activated CD4(+) (CD44(high)/CD45RB(low)) and CD8(+) (CD44(high)/CD45RB(+)) T cells capable of secreting IFN-gamma and of activating macrophages for NO production and mycobacterial growth inhibition. However, significantly more CD8(+) T cells were accumulated in the lungs of resistant A/Sn and F(1) compared with I/St mice. About 80% A/Sn and F(1) CD8(+) cells expressed CD44(high)/CD45RB(+) phenotype, while about 40% I/St CD8(+) cells did not express CD45RB marker at week 5 of infection. In contrast, in susceptible I/St mice lung CD4(+) cells proliferated much more strongly in response to mycobacterial sonicate, and a higher proportion of these cells expressed CD95 and underwent apoptosis compared with A/Sn cells. Unseparated lung cells and T cells of I/St origin produced more IL-5 and IL-10, respectively, whereas their A/Sn and F1 counterparts produced more IFN-gamma following infection. F(1) cells overall expressed an intermediate phenotype between the two parental strains. Such a more balanced type of immune reactivity could be linked to a better TB defense.