Putrescine transport in a cyanobacterium Synechocystis sp. PCC 6803

The transport of putrescine into a moderately salt tolerant cyanobacterium Synechocystis sp. PCC 6803 was characterized by measuring the uptake of radioactively-labeled putrescine. Putrescine transport showed saturation kinetics with an apparent K(m) of 92 +/- 10 microM and V(max) of 0.33 +/- 0.05 nmol/min/mg protein. The transport of putrescine was pH-dependent with highest activity at pH 7.0. Strong inhibition of putrescine transport was caused by spermine and spermidine whereas only slight inhibition was observed by the addition of various amino acids. These results suggest that the transport system in Synechocystis sp. PCC 6803 is highly specific for polyamines. Putrescine transport is energy-dependent as evidenced by the inhibition by various metabolic inhibitors and ionophores. Slow growth was observed in cells grown under salt stress. Addition of low concentration of putrescine could restore growth almost to the level observed in the absence of salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased putrescine transport with an optimum 2-fold increase at 20 mosmol/kg. The stimulation of putrescine transport mediated by osmotic upshift was abolished in chloramphenicol-treated cells, suggesting possible involvement of an inducible transport system.     

Effect of dietary supplementation with sea buckthorn (Hippophaë rhamnoides) seed and pulp oils on the fatty acid composition of skin glycerophospholipids of patients with atopic dermatitis

Sea buckthorn (Hippopha? rhamnoides) seed and pulp oils have traditionally been used for treating skin diseases in China and Russia, but are not widely used in other countries. A placebo-controlled, parallel study was carried out to investigate the effects of these oils on the fatty acid composition of skin glycerophospholipids of patients with atopic dermatitis. Sixteen patients ate 5 g of sea buckthorn seed oil, pulp oil, or paraffin oil daily for 4 months. Skin fatty acids were analyzed with gas chromatography before and after treatment. The seed oil slightly increased the proportion of docosapentaenoic acid (22:5n-3) and decreased the proportion of palmitic acid (16:0) in skin glycerophospholipids (0.05 < P < 0.1). The levels of the other fatty acids remained stable. The results show that the fatty acid composition of skin glycerophospholipids is well buffered against short-term dietary modification.     

Rab13 is upregulated during osteoclast differentiation and associates with small vesicles revealing polarized distribution in resorbing cells

Osteoclasts are bone-resorbing multinucleated cells that undergo drastic changes in their polarization due to heavy vesicular trafficking during the resorption cycle. These events require the precise orchestration of membrane traffic in order to maintain the unique characteristics of the different membrane domains in osteoclasts. Rab proteins are small GTPases involved in regulation of most, if not all, steps of vesicle trafficking. The investigators studied RAB genes in human osteoclasts and found that at least 26 RABs were expressed in osteoclasts. Out of these, RAB13 gene expression was highly upregulated during differentiation of human peripheral blood monocytic cells into osteoclasts. To study its possible function in osteoclasts, the investigators performed immunolocalization studies for Rab13 and various known markers of osteoclast vesicular trafficking. Rab13 localized to small vesicular structures at the superior parts of the osteoclast between the trans-Golgi network and basolateral membrane domain. Rab13 localization suggests that it is not involved in endocytosis or transcytosis of bone degradation products. In addition, Rab13 did not associate with early endosomes or recycling endosomes labeled with EEA1 or TRITC-conjugated transferrin, respectively. Its involvement in glucose transporter traffic was excluded as well. It is suggested that Rab13 is associated with a putative secretory function in osteoclasts.     

Improved classification of Alzheimer's disease data via removal of nuisance variability

Diagnosis of Alzheimer's disease is based on the results of neuropsychological tests and available supporting biomarkers such as the results of imaging studies. The results of the tests and the values of biomarkers are dependent on the nuisance features, such as age and gender. In order to improve diagnostic power, the effects of the nuisance features have to be removed from the data. In this paper, four types of interactions between classification features and nuisance features were identified. Three methods were tested to remove these interactions from the classification data. In stratified analysis, a homogeneous subgroup was generated from a training set. Data correction method utilized linear regression model to remove the effects of nuisance features from data. The third method was a combination of these two methods. The methods were tested using all the baseline data from the Alzheimer's Disease Neuroimaging Initiative database in two classification studies: classifying control subjects from Alzheimer's disease patients and discriminating stable and progressive mild cognitive impairment subjects. The results show that both stratified analysis and data correction are able to statistically significantly improve the classification accuracy of several neuropsychological tests and imaging biomarkers. The improvements were especially large for the classification of stable and progressive mild cognitive impairment subjects, where the best improvements observed were 6% units. The data correction method gave better results for imaging biomarkers, whereas stratified analysis worked well with the neuropsychological tests. In conclusion, the study shows that the excess variability caused by nuisance features should be removed from the data to improve the classification accuracy, and therefore, the reliability of diagnosis making.     

Characterization of the active microbiotas associated with honey bees reveals healthier and broader communities when colonies are genetically diverse

Recent losses of honey bee colonies have led to increased interest in the microbial communities that are associated with these important pollinators. A critical function that bacteria perform for their honey bee hosts, but one that is poorly understood, is the transformation of worker-collected pollen into bee bread, a nutritious food product that can be stored for long periods in colonies. We used 16S rRNA pyrosequencing to comprehensively characterize in genetically diverse and genetically uniform colonies the active bacterial communities that are found on honey bees, in their digestive tracts, and in bee bread. This method provided insights that have not been revealed by past studies into the content and benefits of honey bee-associated microbial communities. Colony microbiotas differed substantially between sampling environments and were dominated by several anaerobic bacterial genera never before associated with honey bees, but renowned for their use by humans to ferment food. Colonies with genetically diverse populations of workers, a result of the highly promiscuous mating behavior of queens, benefited from greater microbial diversity, reduced pathogen loads, and increased abundance of putatively helpful bacteria, particularly species from the potentially probiotic genus Bifidobacterium. Across all colonies, Bifidobacterium activity was negatively correlated with the activity of genera that include pathogenic microbes; this relationship suggests a possible target for understanding whether microbes provide protective benefits to honey bees. Within-colony diversity shapes microbiotas associated with honey bees in ways that may have important repercussions for colony function and health. Our findings illuminate the importance of honey bee-bacteria symbioses and examine their intersection with nutrition, pathogen load, and genetic diversity, factors that are considered key to understanding honey bee decline.     

Single nucleotide polymorphism -799C/T in matrix metalloproteinase-8 promoter region in arterial disease

Arterial disease is associated with elevated serum matrix metalloproteinase (MMP)-8 concentration. We studied the role of two promoter region single nucleotide polymorphisms (SNPs) of MMP-8 gene in the arterial disease. The population comprised patients with arterial disease (n?=?124) and healthy blood donors (n?=?100) as a reference group for MMP-8 SNPs (-799C/T and -381A/G) genotypes and serum concentrations. Genotype frequencies for MMP-8 -799C/T SNP in arterial disease were C/C (43.5%), C/T (32.3%) and T/T (24.2%), and in the reference group they were C/C (50.0%), C/T (40.0%) and T/T (10.0%; P?=?0.012). The -799C allele frequency was lower in the patients (59.7%) than in the reference group (70.0%; P?=?0.023). The -799C allele showed protective effects against the arterial disease with an odds ratio [95% confidence interval (CI)] of 0.372 (0.141-0.980, P?=?0.045) after adjustment for age, gender, and serum MMP-8 and TIMP-1 concentrations. Only in the reference group and whole study population (n?=?224), the -799TT genotype significantly associated with an increase in serum MMP-8 concentrations (P?=?0.047, 0.025). The -799C allele appeared protective against the arterial disease. The genotype may have an effect on systemic MMP-8 levels which could not, however, be seen in the arterial disease patients probably as a result of the strong inflammation involved in the disease pathogenesis.     

Controls of organic and inorganic carbon in randomly selected Boreal lakes in varied catchments

Organic and inorganic carbon concentrations in lakes and the links to catchment and water quality were studied in variable landscapes using the Finnish Lake Survey data base including 874 randomly selected lakes sampled during autumn overturn. The median total organic carbon (TOC) in these boreal lakes was 7.8 mg l^?1, the median total inorganic carbon (TIC) 1.6 mg l^?1 and the median partial pressure of CO₂ (pCO₂) 900 μatm. When the data was divided into subgroups according to land use in the catchment, the proportion of TIC of the total carbon (TC) in lakes was highest (31%) in agricultural areas and lowest (10%) in peatland areas. Elevated TIC concentrations were associated with agricultural land in the catchment, whereas elevated TOC concentrations were observed in lakes with high peatland proportion in the catchment. Two contrasting important sources of CO₂ in lakes were identified on the basis of statistical analysis of the data; weathering processes in the catchments and decomposition of organic matter. CO₂ was also strongly associated with total nutrients TN and TP, implying the importance of quality of organic matter and availability of nutrients for the decomposition processes.