The properties and contribution of the Corynebacterium glutamicum MscS variant to fine-tuning of osmotic adaptation

Based on sequence similarity, the mscCG gene product of Corynebacterium glutamicum belongs to the family of MscS-type mechanosensitive channels. In order to investigate the physiological significance of MscCG in response to osmotic shifts in detail, we studied its properties using both patch-clamp techniques and betaine efflux kinetics. After heterologous expression in an Escherichiacoli strain devoid of mechanosensitive channels, in patch-clamp analysis of giant E. coli spheroplasts MscCG showed the typical pressure dependent gating behavior of a stretch-activated channel with a current/voltage dependence indicating a strongly rectifying behavior. Apart from that, MscCG is characterized by significant functional differences with respect to conductance, ion selectivity and desensitation behavior as compared to MscS from E. coli. Deletion and complementation studies in C. glutamicum showed a significant contribution of MscCG to betaine efflux in response to hypoosmotic conditions. A detailed analysis of concomitant betaine uptake (by the betaine transporter BetP) and efflux (by MscCG) under hyperosmotic conditions indicates that MscCG may act in osmoregulation in C. glutamicum by fine-tuning the steady state concentration of compatible solutes in the cytoplasm which are accumulated in response to hyperosmotic stress.     

A randomized, rater-blinded, crossover study comparing the clinical efficacy of Ritalin® LA (methylphenidate) treatment in children with attention-deficit hyperactivity disorder under different breakfast conditions over 2 weeks

Several extended-release methylphenidate medications are available for treatment of children with ADHD. Pharmacokinetic investigations suggest that the serum levels of methylphenidate are partially altered when the medication is taken without breakfast. Clinical data comparing different breakfast situations are missing. In this study, different breakfast compositions and their influence on treatment with Ritalin LA are investigated. A total of 150 patients were enrolled in a rater-blinded, randomized crossover trial that compared a minimal breakfast with a standard breakfast in patients under stable treatment with Ritalin LA. Ratings for clinical efficacy were carried out after 1 week by teachers and parents (FBB-ADHS), as well as physicians (CGI). Additionally, a math test was administered to the patients. Of the total patients, 144 finished the trial with a breakfast compliance of 93%. All of the clinical rating scales showed consistently no difference between the two breakfast conditions. Non-inferiority of minimal breakfast versus standard breakfast was shown to be statistically significant (FBB-AHDS(Teacher): 0.97 with minimal breakfast, 1.01 with standard breakfast, P < 0.0001). The clinical efficacy of Ritalin LA is not influenced by breakfast and works independently of food intake.     

Influence of castration-induced testosterone and estradiol deficiency on obesity and glucose metabolism in male Göttingen minipigs

Low testosterone and estradiol concentrations are predictive for the development of the metabolic syndrome in men and women, respectively. The aim of this study was to investigate the influence of sex hormone deficiency on food intake, body weight, body composition and glucose metabolism in male Göttingen minipigs.Five adult male Göttingen minipigs were studied before castration (pre-cast), 10-18 days (post-cast 1) and 10-11 weeks (post-cast 2) after castration. Parameters of interest were food intake, body weight, body fat percentage and sex hormone concentrations. Furthermore glucose tolerance, glucagon suppression, insulin resistance, beta cell function and disposition index were evaluated by oral and intravenous glucose tolerance tests.Castration led to almost complete disappearance of circulating testosterone and estradiol and secondarily to increased food intake, body weight and body fat percentage. Ten-eighteen days sex hormone deficiency (post-cast 1) did not significantly change any of the investigated metabolic parameters compared to pre-cast levels. Ten weeks after castration (post-cast 2) significant insulin resistance, glucose intolerance and hyperglucagonemia was found, and the beta cell function and the disposition index both were decreased.In conclusion, castration-induced sex hormone deficiency in male Göttingen minipigs results in hyperphagia, obesity and disturbed glucose metabolism, which are some of the features typical for the human metabolic syndrome.     

Genetic structure among sorghum landraces as revealed by morphological variation and microsatellite markers in three agroclimatic regions of Burkina Faso

Diversity among 124 sorghum landraces from 10 villages surveyed in 3 regions of Burkina Faso covering different agroecological zones was assessed by 28 agromorphological traits and 29 microsatellite markers. 94.4% of the landraces collected belonged to the botanical race guinea (consisting of 96.6% guinea gambicum and 3.4% guinea margaritiferum), 74.2% had white kernels, 13.7% had orange and 12.1% had red kernels. Compared to the “village nested within zone” factor, the “variety nested within village within zone” factor predominately contributed to the diversity pattern for all nine statistically analysed quantitative traits. The multivariate analyses performed on ten morphological traits identified five landrace groups, and of these, the red kernel sorghum types appeared the most homogenous. 2 to 17 alleles were detected per locus with a mean 4.9 alleles per locus and a gene diversity (He) of 0.37. Landraces from the sub-Sahelian zone had the highest gene diversity (He = 0.38). Cluster analysis revealed that the diversity was weakly stratified and could not be explained by any biophysical criteria. One homogenous guinea margaritiferum group was distinguished from other guinea landraces. The red kernel type appeared to be genetically distinct from all other guinea landraces. The kernel colour was the principal structuring factor. This is an example of a homogeneous group of varieties selected for a specific use (for local beer preparation), mainly grown around the households in compound fields, and presenting particular agromorphological and genetic traits. This is the most original feature of sorghum diversity in Burkina Faso and should be the focus of special conservation efforts.     

Stable Isotope Analysis Reveals Detrital Resource Base Sources of the Tree Hole Mosquito, Aedes triseriatus

1. Detritus that forms the basis for mosquito production in tree hole ecosystems can vary in type and timing of input. We investigated the contributions of plant- and animal-derived detritus to the biomass of Aedes triseriatus (Say) pupae and adults by using stable isotope ((15)N and (13)C) techniques in lab experiments and field collections.2. Lab-reared mosquito isotope values reflected their detrital resource base, providing a clear distinction between mosquitoes reared on plant or animal detritus.3. Isotope values from field-collected pupae were intermediate between what would be expected if a single (either plant or animal) detrital source dominated the resource base. However, mosquito isotope values clustered most closely with plant-derived values, and a mixed feeding model analysis indicated tree floral parts contributed approximately 80% of mosquito biomass. The mixed model also indicated that animal detritus contributed approximately 30% of mosquito tissue nitrogen.4. Pupae collected later in the season generally had isotope values that were consistent with an increased contribution from animal detritus, suggesting this resource became more nutritionally important for mosquitoes as plant inputs declined over the summer.     

Synthesis of linear and comb-like peptide constructs containing up to four copies of a T cell epitope and their capacity to stimulate T cells.

Polypeptide constructs containing up to four copies of the T cell epitope 306-318 of influenza virus haemagglutinin have been synthesized on solid phase. Between the copies, a non-natural PEG-based spacer amino acid has been introduced. The oligomeric epitopes were analysed by RP-HPLC and ES-MS. The arrangement of the epitopes within the peptide constructs was either linear or comb-like. The proliferative response in a T helper cell assay induced by these oligomerized epitopes has been tested, showing that the linearly arranged epitopes are more effective than the comb-like oligomers.     

The role of TGF-beta1 as a determinant of foreign body reaction to alloplastic materials in rat fibroblast cultures: comparison of different commercially available polypropylene meshes for hernia repair

BACKGROUND: Animal experiments on hernia repair demonstrated better biocompatibility of light-weight polypropylene meshes. However, implanted medical devices trigger a variety of adverse tissue responses, such as inflammation, fibrosis, infection and thrombosis, but the mechanisms involved in such responses remain largely unknown. This study aimed to determine the effect of transforming growth factor beta1 (TGF-beta1) on host tolerance by quantification of foreign body reaction in cultured fibroblasts depending on the amount and composition of implanted material used for hernia repair. MATERIALS AND METHODS: An NRK-49F fibroblast culture was incubated in the presence of 4 commercially available meshes approved for hernia repair. A mesh-free cell suspension served as a control group, in which the influence of TGF-beta1 on fibroblasts was evaluated. Levels of TGF-beta1 in the supernatant were dynamically measured in a time interval of 6 to 96 h and cell proliferation rates were assessed colorimetrically using MTT test. RESULTS: A dose-dependent suppression of fibroblasts proliferation by TGF-beta1 was observed. All meshes suppressed the secretion of TGF-beta1 and conversely increased significantly cell proliferation in comparison to the control group (p<0.01) in the first 24 to 48 h of incubation. That effect was more pronounced in meshes partially containing absorbable material when compared to samples of pure polypropylene meshes (p<0.05) and to the control group (p<0.001). CONCLUSION: Our experiment revealed that early biological reaction of connective tissue cells towards polypropylene meshes and their variants depended much more on the composition and type of the material than on its absolute amount. The assumption that material weight reduction alone might affect the foreign body reaction of mesh implants could not be confirmed by our in vitro study.     

High cell density cultivation of recombinant yeasts and bacteria under non-pressurized and pressurized conditions in stirred tank bioreactors

This study demonstrates the applicability of pressurized stirred tank bioreactors for oxygen transfer enhancement in aerobic cultivation processes. The specific power input and the reactor pressure was employed as process variable. As model organism Escherichia coli, Arxula adeninivorans, Saccharomyces cerevisiae and Corynebacterium glutamicum were cultivated to high cell densities. By applying specific power inputs of approx. 48kWm(-3) the oxygen transfer rate of a E. coli culture in the non-pressurized stirred tank bioreactor was lifted up to values of 0.51moll(-1)h(-1). When a reactor pressure up to 10bar was applied, the oxygen transfer rate of a pressurized stirred tank bioreactor was lifted up to values of 0.89moll(-1)h(-1). The non-pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities of more than 40gl(-1) cell dry weight (CDW) of E. coli, whereas the pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities up to 225gl(-1) CDW of A. adeninivorans, 89gl(-1) CDW of S. cerevisiae, 226gl(-1) CDW of C. glutamicum and 110gl(-1) CDW of E. coli. Compared to literature data, some of these cell densities are the highest values ever achieved in high cell density cultivation of microorganisms in stirred tank bioreactors. By comparing the specific power inputs as well as the k(L)a values of both systems, it is demonstrated that only the pressure is a scaleable tool for oxygen transfer enhancement in industrial stirred tank bioreactors. Furthermore, it was shown that increased carbon dioxide partial pressures did not remarkably inhibit the growth of the investigated model organisms.