The replicative helicase MCM recruits cohesin acetyltransferase ESCO2 to mediate centromeric sister chromatid cohesion

Chromosome segregation depends on sister chromatid cohesion which is established by cohesin during DNA replication. Cohesive cohesin complexes become acetylated to prevent their precocious release by WAPL before cells have reached mitosis. To obtain insight into how DNA replication, cohesion establishment and cohesin acetylation are coordinated, we analysed the interaction partners of 55 human proteins implicated in these processes by mass spectrometry. This proteomic screen revealed that on chromatin the cohesin acetyltransferase ESCO2 associates with the MCM2‐7 subcomplex of the replicative Cdc45‐MCM‐GINS helicase. The analysis of ESCO2 mutants defective in MCM binding indicates that these interactions are required for proper recruitment of ESCO2 to chromatin, cohesin acetylation during DNA replication, and centromeric cohesion. We propose that MCM binding enables ESCO2 to travel with replisomes to acetylate cohesive cohesin complexes in the vicinity of replication forks so that these complexes can be protected from precocious release by WAPL. Our results also indicate that ESCO1 and ESCO2 have distinct functions in maintaining cohesion between chromosome arms and centromeres, respectively.     

The Effect of Lactobacillus salivarius SGL03 on Clinical and Microbiological Parameters in Periodontal Patients

The destruction of periodontal tissues during periodontitis is the result of the immune-inflammatory reactions to the bacteria of dental biofilm. Probiotics may reduce dysbiosis by the modification of the dental microbiome, which can influence the immune-inflammatory mechanisms. The aim of this study was to estimate the clinical and microbiological parameters, before and after 30 days of application of the dietary supplement containing Lactobacillus salivarius SGL03 or placebo. The study was conducted in 51 patients with stage I or II periodontitis during the maintenance phase of treatment. The clinical parameters and the number of colony forming units (CFU) of bacteria in supragingival plaque were assessed before and after 30 days of the oral once daily administration of the dietary supplement in the form of suspension containing L. salivarius SGL03 or placebo. There were no changes in the PI scores between and within the groups. The value of BOP decreased in both groups. In the study group the significant reduction of the mean pocket depth was revealed (from 2.5 to 2.42, p = 0,027) but without the difference between the groups. There were no significant changes in the number of bacteria within the groups. In the control, but not the study group, positive correlations were observed between the clinical parameters (variables) and the number of bacteria. The use of the dietary supplement containing L. salivarius SGL03 may reduce pocket depth despite the lack of changes in other clinical parameters and the number of bacteria in supragingival plaque.Key words: probiotics, periodontal treatment, Lactobacillus salivarius     

Effect of a beta-adrenergic antagonist on blood pressure, heart rate and beta-adrenoceptors in turkey poults

An irreversible beta-adrenergic blocker, bromoacetylalprenololmenthane (BAAM), was administered both peripherally and centrally to turkey poults, Meleagris gallopavo. Peripheral administration of BAAM (60 mg/kg body weight) effected a significant reduction in blood pressure and heart rate. Twenty minutes postinjection, mean blood pressure and heart rate were reduced 34.5 and 24.2%, respectively. Two days later, mean blood pressure values remained significantly depressed at 17.3% below preinjection determinations. Biochemical analysis of heart tissue following peripheral (intraperitoneal) injections of BAAM (60 mg/kg body weight) showed a significant decrease in beta-adrenergic receptors (BAR). Little or no change in the number of BAR in brain tissue was observed. Central (intraventricular) administration of BAAM (0.72 mg/g brain weight) resulted in no change in mean blood pressure or heart rate during a 20 min postinjection period. Biochemical analysis of heart tissue following central injections of BAAM showed little or no change in the number of BAR. There was, however, a significant decrease in the number of BAR in brain tissue.     

Presynaptic calcium signals during neurotransmitter release: detection with fluorescent indicators and other calcium chelators.

Synthetic calcium buffers, including fluorescent calcium indicators, were microinjected into squid 'giant' presynaptic nerve terminals to investigate the calcium signal that triggers neurotransmitter secretion. Digital imaging methods, applied in conjunction with the fluorescent calcium indicator dye fura-2, reveal that transient rises in presynaptic calcium concentration are associated with action potentials. Transmitter release terminates within 1-2 ms after a train of action potentials, even though presynaptic calcium concentration remains at micromolar levels for many seconds longer. Microinjection of the calcium buffer, EGTA, into the presynaptic terminal has no effect on transmitter release evoked by single presynaptic action potentials. EGTA injection does, however, block the change in calcium concentration measured by fura-2. Therefore, the calcium signal measured by fura-2 is not responsible for triggering release. These results suggest that the rise in presynaptic calcium concentration that triggers release must be highly localized to escape detection with fura-2 imaging. Unlike EGTA, microinjection of BAPTA--a calcium buffer with an equilibrium affinity for calcium similar to that of EGTA--produces a potent, dose-dependent, and reversible block of action-potential evoked transmitter release. The superior ability of BAPTA to block transmitter release apparently is due to the more rapid calcium-binding kinetics of BAPTA compared to EGTA. Because EGTA should bind calcium within a few tens of microseconds under the conditions of our experiments, the inability of EGTA to block release indicates that transmitter release is triggered within a few tens of microseconds after the entry of calcium into the presynaptic terminal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neuronal Ca2+ signalling takes the local route.

The past year has seen several sets of experimental results demonstrate that fast, large and highly localized rises in intracellular Ca2+ concentration can occur in neurons. These results confirm previous theoretical predictions of acute spatial compartmentalization of Ca2+ signalling, and document a form of signalling that may occur whenever rapid and local signal processing is the goal. The dimensions involved present severe challenges for attempts to directly measure these signalling events.     

Complex permittivity of representative biological solutions in the 2–67 GHz range

The main purpose of this study is to provide experimental data on the complex permittivity of some biological solutions in the 2–67 GHz range at room and human body temperatures. The permittivity measurements are performed using an open‐ended coaxial probe. Permittivity spectra of several representative monomolecular solutions of proteins, amino acids, nucleic acids, and carbohydrates are analyzed and compared. Furthermore, measurements have also been performed for complex biomolecular solutions, including bovine serum albumin (BSA)–DNA–glucose mixture, culture medium, and yeast extract solution. The results demonstrate that for concentrations below 1%, the permittivity spectra of the solutions do not substantially differ from that of distilled water. Measurements carried out for 4% and 20% BSA solutions show that the presence of proteins results in a decrease in permittivity. For highly concentrated RNA solutions (3%), a slight increase in the imaginary part of the permittivity is observed below 10 GHz. Experimental data show that free water permittivity can be used for modeling of the culture medium above 10 GHz. However, at lower frequencies a substantial increase in the imaginary part of the permittivity due to ionic conductivity should be carefully taken into account. A similar increase has also been observed for the yeast extract solution in the lower frequency region of the considered spectrum. Above 10 GHz, the high concentration of proteins and other low‐permittivity components of the yeast extract solution results in a decrease in the complex permittivity compared to that of water. Obtained data are of utmost importance for millimeter‐wave dosimetry studies. Bioelectromagnetics 33:346–355, 2012. © 2011 Wiley Periodicals, Inc.     

Performance Measurement Via Sap Flow Monitoring of Three Eucalyptus Species for Mine Site and Dryland Salinity Phytoremediation

Monitoring of trees with reliable technology is essential in phytoremediation. Sap flow instrumentation on three Eucalyptus species at a mine site in western Victoria, Australia, was used to determine which species is best suited to meet the goals of a phytoremediation project. Specifically, the aim of the monitoring was to determine which species could better tolerate the hypersaline soil, potentially lower saline ground water, and cope with expected hotter and drier weather given climate change scenarios. Over a summer period, average daily water use of E. cladocalyx was approximately six times greater than E. melliodora and four times greater than E. polybractea. During a three day heat wave event, E. cladocalyx was found to have a higher tolerance to extreme temperature. The optimal VPD / temperature for tree transpiration was 2.6 kPa / 26.2 °C for E. cladocalyx, 2.1 kPa / 23.9 °C for E. melliodora, and 2.0 kPa / 23.2 °C for E. polybractea. Through sap flow monitoring, it was determined that E. cladocalyx could better tolerate saline soils, hotter and drier weather, and had greater potential to lower saline ground water.     

“Remapping the Fabric of the African Self: A Synoptic Theory”

A thorough knowledge of the synoptic structure and contents of the modern African self is essential for an improved understanding of the Africa of the 21st century. This lack has compelled practitioners to continue to use the Western model of the self as a substitute for the African perspective. This situation is, however, regrettable, since the Western notion of the self is largely incompatible with the African view. The Western model is based on the notion of the self as a demarcated entity set off against the world, whereas the African views the self as an entity in close interaction with the multi-faceted aspects of his world. This paper is an attempt to correct this imbalance. It offers a synoptic theory of the fabric of the modern African self.