ParA of Mycobacterium smegmatis co‐ordinates chromosome segregation with the cell cycle and interacts with the polar growth determinant DivIVA

Mycobacteria are among the clinically most important pathogens, but still not much is known about the mechanisms of their cell cycle control. Previous studies suggested that the genes encoding ParA and ParB (ATPase and DNA binding protein, respectively, required for active chromosome segregation) may be essential in Mycobacterium tuberculosis. Further research has demonstrated that a Mycobacterium smegmatis parB deletion mutant was viable but exhibited a chromosome segregation defect. Here, we address the question if ParA is required for the growth of M. smegmatis, and which cell cycle processes it affects. Our data show that parA may be deleted, but its deletion leads to growth inhibition and severe disturbances of chromosome segregation and septum positioning. Similar defects are also caused by ParA overproduction. EGFP–ParA localizes as pole‐associated complexes connected with a patch of fluorescence accompanying two ParB complexes. Observed aberrations in the number and positioning of ParB complexes in the parA deletion mutant indicate that ParA is required for the proper localization of the ParB complexes. Furthermore, it is shown that ParA colocalizes and interacts with the polar growth determinant Wag31 (DivIVA homologue). Our results demonstrate that mycobacterial ParA mediates chromosome segregation and co‐ordinates it with cell division and elongation.     

Varied approach of using MSCs for bovine embryo in vitro culture

The objective of the present study was to evaluate the effect of porcine Mesenchymal Stem Cells (MSCs) secreted factors on bovine in vitro embryo development by using MSCs in different culture systems: SOF medium, SOF medium conditioned by MSCs in monolayer and in reverse drop and by embryo culture in co-culture with MSCs. Statistically highly significant differences were noted between the number of blastocysts derived cultures in all tested culture systems. The in vitro culture in SOF turned out to be the most optimal. Statistically highly significant differences were observed in the number of blastocyst obtained between SOF and SOF in co-culture with MSCs (p?<?0.0001), and between SOF and SOF conditioned (monolayer and drop) (p?<?0.00001). The trials to produce blastocysts in SOF conditioned by MSCs in reverse drops and monolayer failed. The blastocysts were obtained and analysed by TUNEL only in two out of four experimental groups: SOF and SOF in co-culture with MSCs. There were no significant differences between any of analysed blastocysts’ groups neither in the total number of nuclei nor in the apoptotic features. Neither medium conditioning by MSCs in monolayer and in reverse drop nor embryo culture in co-culture with MSC turned out to be effective.     

Expression and functional characterization of P2Y1 and P2Y12 nucleotide receptors in long-term serum-deprived glioma C6 cells

We characterized the expression and functional properties of the ADP-sensitive P2Y(1) and P2Y(12) nucleotide receptors in glioma C6 cells cultured in medium devoid of serum for up to 96 h. During this long-term serum starvation, cell morphology changed from fibroblast-like flat to round, the adhesion pattern changed, cell-cycle arrest was induced, extracellular signal-regulated kinase (ERK1/2) phosphorylation was reduced, Akt phosphorylation was enhanced, and expression of the P2Y(12) receptor relative to P2Y(1) was increased. These processes did not reflect differentiation into astrocytes or oligodendrocytes, as expression of glial fibrillary acidic protein and NG2 proteoglycan (standard markers of glial cell differentiation) was not increased during the serum deprivation. Transfer of the cells into fresh medium containing 10% fetal bovine serum reversed the changes. This demonstrates that serum starvation caused only temporary growth arrest of the glioma C6 cells, which were ready for rapid division as soon as the environment became more favorable. In cells starved for 72 and 96 h, expression of the P2Y(1) receptor was low, and the P2Y(12) receptor was the major player, responsible for ADP-evoked signal transduction. The P2Y(12) receptor activated ERK1/2 kinase phosphorylation (a known cell proliferation regulator) and stimulated Akt activity. These effects were reduced by AR-C69931MX, a specific antagonist of the P2Y(12) receptor. On the other hand, Akt phosphorylation increased in parallel with the low expression of the P2Y(1) receptor, indicating the inhibitory role of P2Y(1) in Akt pathway signaling. The shift in nucleotide receptor expression from P2Y(1) to P2Y(12) would appear to be a new and important self-regulating mechanism that promotes cell growth rather than differentiation and is a defense mechanism against effects of serum deprivation.     

Epidemiological pattern of classical Borna disease and regional genetic clustering of Borna disease viruses point towards the existence of to-date unknown endemic reservoir host populations

Classical Borna disease (cBD), a non-purulent encephalitis of solipeds and sheep, is endemic in certain areas of central Europe. The etiologic agent is Borna disease virus (BDV), thus far the only member of the family Bornaviridae. Based on epidemiological patterns of cBD and recent phylogenetic findings this review hypothesizes the possible existence of yet unknown BDV reservoir host populations, and analyzes critically BDVs from outside endemic regions.     

Isolation and primary structures of seven serine proteinase inhibitors from Cyclanthera pedata seeds

Seven new trypsin inhibitors, CyPTI I–VII, were purified from ripe seeds of Cyclanthera pedata by affinity chromatography on immobilized chymotrypsin in the presence of 5 M NaCl followed by preparative native PAGE at pH 8.9. The CyPTIs (Cyclanthera pedata trypsin inhibitors) belong to a well-known squash inhibitor family. They contain 28–30 amino acids and have molecular weights from 3031 to 3367 Da. All the isolated inhibitors strongly inhibit bovine β-trypsin (K_a > 10¹¹ M^− 1) and, more weakly, bovine α-chymotrypsin (K_a ≈ 10⁴–10⁶ M^− 1). In the presence of 3 M NaCl the association constants of CyPTIs with α-chymotrypsin increased a few hundred fold. Taking advantage of this phenomenon, a high concentration of NaCl was used to isolate the inhibitors by affinity chromatography on immobilized chymotrypsin. It was found that although one of them, CyPTI IV, had split the Asn25–Gly26 peptide bond, its inhibitory activity remained unchanged. The hydrolyzed bond is located downstream of the reactive site. Presumably, the inhibitor is a naturally occurring, double-chain protein arising during posttranslational modifications.     

Role of FSH and triiodothyronine in Sertoli cell development expressed by formation of connexin 43-based gap junctions

Follicle-stimulating hormone (FSH) and triiodothyronine (T3) are known regulatory factors of spermatogenesis initiation. Connexin 43 (Cx43) is the most ubiquitous constitutive protein of gap junctions in the testis. This study evaluates the effects of the hyperstimulation of FSH and T3 during testicular maturation on Cx43 expression in the testis. The newborn, male Wistar rats were divided randomly into four experimental groups: FSH group-daily injections of FSH 7.5?IU/animal; T3 group-100?μg T3/kg body weight; FSH+T3 group-both substances; A control group-received vehicles in the same volume. Proliferating cell nuclear antigen immunohistochemistry and toluidine blue staining were used to determine the germ cell proliferation and degeneration. Cx43 immunolocalization was evaluated to find Cx43 maturational changes. Under FSH treatment, the proliferation rate was high so the total number of Sertoli cells increased with a low level of degeneration and lumen formation. T3 stimulation evoked a reduction in the proliferation rate and a decrease in Sertoli cell number but with intensive formation of lumen. T3+FSH inhibited the proliferation rate and stimulated lumen formation together with degeneration, which negatively influenced the number of germ cells in the seminiferous epithelium. We conclude that T3 action seems to be particularly connected with the maturation of Cx43 gap junctions. FSH stimulates maturation of Sertoli cell function, but this effect may take place regardless of the presence of Cx43-dependent intercellular communication. The hyperstimulation of both FSH and T3 damages Cx43 connections and hence evokes regressional changes in the seminiferous epithelium.     

Implant supported dentures: an estimation of chewing efficiency

doi: 10.1111/j.1741‐2358.2009.00303.x
Implant supported dentures: an estimation of chewing efficiency Background: Treatment of edentulous patients is one of the most demanding tasks the dentist can meet in his everyday practice. Implant based methods help to improve functioning of dentures and life quality of so treated patients. Objectives: The aim of the study was to evaluate the chewing efficiency of patients treated with lower complete implant‐supported overdentures and the simultaneous evaluation of treatment results by patients. Materials and methods: For the investigation were chosen edentulous patients, treated with upper conventional complete dentures and lower complete overdentures supported on two implants. In this group of patients, were conducted investigations of chewing efficiency changes, based on the Optocal test and overdentures functioning evaluation made by patients in the survey. Results: The objective evaluation of the chewing efficiency indicated the decrease of this value in the five years of observations. Lower complete overdentures supported on implants significantly increased the comfort of chewing of edentulous patients. Conclusions: The results of the study let us to assess positively the result of the therapy using titanium implants and lower complete overdentures. The therapy described significantly increases the life comfort of the edentulous patients. Decreasing chewing efficiency indicated by the research result should be compensated with the dentures maintaining or the prostheses exchange after about five years of use.     

Characterization of bone-marrow-derived rat mesenchymal stem cells depending on donor age

It is generally accepted that autologous transfers, as non-immunogenic, constitute the safest approach in cellular transplantations. However, this attitude is often associated with the need for isolation and extracorporeal propagation of cells derived from aged patients. Thus the knowledge about relationship between aging and the properties of MSCs (mesenchymal stem cells) is crucial in developing new clinical strategies. The aim of this study was to perform complex comparison of MSC derived from young and aged individuals, which included phenotype, proliferating rate, osteogenic and adipogenic potential and secretory activity. Evaluated populations were isolated from bone marrow of 3-month-old and 24-month-old rats. There was no significant difference in membrane antigen expression and PDT (population doubling time). Additionally, the adipogenic and osteogenic potential did not vary between studied populations. The reaction of MSCs to either mitogen [bFGF (basic fibroblas t growth factor)] or oxidative stress (H2O2) in vitro displayed a very similar pattern in both analysed populations. There was no difference in TGFβ1 (transforming growth factor β1) and VEGF (vascular endothelial growth factor) secretion measured by ELISA test and gene expression evaluated by real-time PCR. However, the expression of the gene for IL-1α (interleukin-1α) was 8-fold lower in oMSC (MSC isolated from old rats). These results indicate that aging individuals can be considered as candidates for autologous transplantation of bone-marrow-derived MSCs.     

Effect of the myosin light chain kinase inhibitor ML-7 on the proteome of hearts subjected to ischemia-reperfusion injury

In the development of ischemia/reperfusion (I/R) injury, the role of the myosin light chain (MLC) phosphorylation has been given increased consideration. ML-7, a MLC kinase inhibitor, has been shown to protect cardiac function from I/R, however the exact mechanism remains unclear. Isolated rat hearts were perfused under aerobic conditions (controls) or subjected to I/R in the presence or absence of ML-7. Continuous administration of ML-7 (5 μM) from 10 min before onset of ischemia to the first 10 min of reperfusion resulted in significant recovery of heart contractility. Analysis of gels from two-dimensional electrophoresis revealed eight proteins with decreased levels in I/R hearts. Six proteins are involved in energy metabolism:ATP synthase beta subunit, cytochrome b-c1 complex subunit 1, 24-kDa mitochondrial NADH dehydrogenase, NADH dehydrogenase [ubiquinone] iron-sulfur protein 8, cytochrome c oxidase subunit, and succinyl-CoA ligase subunit. The other two proteins with decreased levels in I/R hearts are: peroxiredoxin-2 and tubulin. Administration of ML-7 increased level of succinyl-CoA ligase, key enzyme involved in the citric acid cycle. The increased level of succinyl-CoA ligase in I/R hearts perfused with ML-7 suggests that the cardioprotective effect of ML-7, at least partially, also may involve increase of energy production.