Do Leptin Levels Predict Weight Gain?—A 5-Year Follow-Up Study in Mauritius

Objective : To investigate whether relative baseline leptin levels predict long-term changes in adiposity and/or its distribution. Research Methods and Procedures : In a longitudinal study of 2888 nondiabetic Mauritians aged 25 years to 74 years who participated in population-based surveys in 1987 and 1992, changes in body mass index (BMI), waist/hip ratio (WHR), and waist circumference were compared between “hyperleptinemic,” “normoleptinemic,” and “hypoleptinemic” groups. “Relative leptin levels” were calculated as standardized residuals from the regression of log₁₀ leptin on baseline BMI to provide a leptin measure independent of BMI. Analyses were performed within each sex. A linear regression model was used to assess the effect of standardized residuals on changes in BMI, WHR, and waist circumference, independent of baseline BMI, age, fasting insulin, and ethnicity. Results : After adjusting for age and baseline BMI by analysis of covariance, there was no difference in changes in BMI, WHR, or waist circumference between men with low, normal, or high relative leptin levels. Among women, there was a significant difference in ΔWHR across leptin groups, such that the largest increase occurred in the “normal” leptin group. For both men and women, the linear regression models explained ?10% of variation in dependent variables, and the only significant independent variables were age, BMI, and being of Chinese origin, compared with Indian origin. Discussion : These findings do not support a role for leptin concentration in predicting weight gain or changes in fat distribution in adults over a 5-year period.     

A Genome-Wide Association Study of a Biomarker of Nicotine Metabolism

Individuals with fast nicotine metabolism typically smoke more and thus have a greater risk for smoking-induced diseases. Further, the efficacy of smoking cessation pharmacotherapy is dependent on the rate of nicotine metabolism. Our objective was to use nicotine metabolite ratio (NMR), an established biomarker of nicotine metabolism rate, in a genome-wide association study (GWAS) to identify novel genetic variants influencing nicotine metabolism. A heritability estimate of 0.81 (95% CI 0.70–0.88) was obtained for NMR using monozygotic and dizygotic twins of the FinnTwin cohort. We performed a GWAS in cotinine-verified current smokers of three Finnish cohorts (FinnTwin, Young Finns Study, FINRISK2007), followed by a meta-analysis of 1518 subjects, and annotated the genome-wide significant SNPs with methylation quantitative loci (meQTL) analyses. We detected association on 19q13 with 719 SNPs exceeding genome-wide significance within a 4.2 Mb region. The strongest evidence for association emerged for CYP2A6 (min p = 5.77E-86, in intron 4), the main metabolic enzyme for nicotine. Other interesting genes with genome-wide significant signals included CYP2B6, CYP2A7, EGLN2, and NUMBL. Conditional analyses revealed three independent signals on 19q13, all located within or in the immediate vicinity of CYP2A6. A genetic risk score constructed using the independent signals showed association with smoking quantity (p = 0.0019) in two independent Finnish samples. Our meQTL results showed that methylation values of 16 CpG sites within the region are affected by genotypes of the genome-wide significant SNPs, and according to causal inference test, for some of the SNPs the effect on NMR is mediated through methylation. To our knowledge, this is the first GWAS on NMR. Our results enclose three independent novel signals on 19q13.2. The detected CYP2A6 variants explain a strikingly large fraction of variance (up to 31%) in NMR in these study samples. Further, we provide evidence for plausible epigenetic mechanisms influencing NMR.     

The Arabidopsis thaliana cysteine-rich receptor-like kinases CRK6 and CRK7 protect against apoplastic oxidative stress

Receptor-like kinases are important regulators of many different processes in plants. Despite their large number only a few have been functionally characterized. One of the largest subgroups of receptor-like kinases in Arabidopsis is the cysteine-rich receptor like kinases (CRKs). High sequence similarity among the CRKs has been suggested as major cause for functional redundancy. The genomic localization of CRK genes in back-to-back repeats has made their characterization through mutant analysis unpractical. Expression profiling has linked the CRKs with reactive oxygen species, important signaling molecules in plants. Here we have investigated the role of two CRKs, CRK6 and CRK7, and analyzed their role in extracellular ROS signaling. CRK6 and CRK7 are active protein kinases with differential preference for divalent cations. Our results suggest that CRK7 is involved in mediating the responses to extracellular but not chloroplastic ROS production.     

Genetic structure of freshwater Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis> L.) populations from the lakes Onega and Ladoga of northwest Russia and implications for conservation

Freshwater Atlantic salmon (Salmo salar L.) populations are a living example of adaptation to the changing conditions caused by glacial cycles. The uniqueness of these populations is emphasized by almost complete resistance to the dangerous parasite Gyrodactylus salaris. In Europe, freshwater salmon populations occur primarily in north-western Russia in the republic of Karelia. These systems include Lakes Ladoga and Onega, the two largest lakes in Europe, each of which harbours a number of freshwater salmon spawning rivers. We used microsatellite markers to study the genetic structure and temporal stability of 11 freshwater salmon populations in Russian Karelia. Populations clustered according their region of origin. Although temporal variation in allele frequencies was observed in the majority of temporal comparisons, various lines of evidence demonstrated that this influence was relatively minor compared to spatial variation that explained eight times more of the variability than temporal variation. Temporal stability tended to occur in populations from rivers with a higher linear lake coefficient. The high level of genetic structuring observed in both lake systems and the apparent low level of migration between populations suggests that treating each river as a separate management unit is recommended. In addition, as the number of populations is large, the best strategy for such fine scale management would be to ensure that the level of natural reproduction in each river is sufficient to sustain the population. A prioritization strategy for population conservation based on estimating the relative roles of different evolutionary forces shaping the gene pools highlighted a number of populations where further monitoring is warranted and also identified populations which could be prioritized for conservation as living gene banks in the event that conservation resources are limited. This prioritization agreed well with the occurrence of temporal (in)stability.     

Predictive modelling of Fe(III) precipitation in iron removal process for bioleaching circuits

In this study, the applicability of three modelling approaches was determined in an effort to describe complex relationships between process parameters and to predict the performance of an integrated process, which consisted of a fluidized bed bioreactor for Fe³⁺ regeneration and a gravity settler for precipitative iron removal. Self-organizing maps were used to visually evaluate the associations between variables prior to the comparison of two different modelling methods, the multiple regression modelling and artificial neural network (ANN) modelling, for predicting Fe(III) precipitation. With the ANN model, an excellent match between the predicted and measured data was obtained (R ² = 0.97). The best-fitting regression model also gave a good fit (R ² = 0.87). This study demonstrates that ANNs and regression models are robust tools for predicting iron precipitation in the integrated process and can thus be used in the management of such systems.     

Molecular make-up of the glomerular filtration barrier

The glomerular filtration barrier is composed of glomerular endothelial cells, the glomerulus basement membrane and the podocyte cell layer. The filtration barrier is a target of injury in several systemic and renal diseases, and this often leads to progressive renal disease and kidney failure. Therefore, it is essential to understand the molecular biology of the glomerulus. During the last two decades, a lot of new information about molecular components of the glomerulus filtration barrier has been generated. Many of the key discoveries have been obtained through studies on the genetic background of inherited glomerular diseases. These studies have emphasized the role of podocytes in the filtration barrier function. During the last decade, the use of knockout mouse technology has become more available and given important new insights into the functional significance of glomerular components. Large-scale approaches, such as microarray profiling, have also given data about molecules involved in the biology and pathology of the glomerulus. In the coming decade, the use of global expression profiling platforms, transgenic mouse lines, and other in vivo gene delivery methods will rapidly expand our understanding of biology and pathology of the glomerular filtration barrier, and hopefully expose novel target molecules for therapy in progressive renal diseases.     

Detection and quantitation of colored deposit-forming <Emphasis Type="Italic">Meiothermus</Emphasis> spp. in paper industry processes and end products

Colored biofilms cause problems in paper industry. In this work we used real-time PCR to detect and to quantitate members of the genus Meiothermus from the process samples and end products from 24 machines manufacturing pulp, paper and board in four countries. The results obtained from 200 samples showed the importance of members of the genus Meiothermus as ubiquitous biofoulers in paper machines. This genus was the dominant biofouler in some mills. From ≤10⁴ to 10¹¹ copies of Meiothermus 16S rRNA genes were found per gram of process deposit (wet weight). Meiothermus spp. were found in paper and board products with colored defects and connection between deposit-forming microbes and end-product spots was shown. 16S rRNA gene sequences of 29 biofilm producing bacterial isolates from different mills were determined. Based on sequence data, 25 of the isolates were assigned to the genus Meiothermus, with Meiothermus silvanus and M. ruber as the most frequent species.     

Aviation noise does not impair the reproductive success of farmed blue foxes

The aim of our study was to assess the effects of aviation noise on reproduction and cub mortality in farmed blue foxes. Eighty artificially inseminated blue fox vixens (45 primiparous and 35 multiparous) were exposed to aviation noise on 5 days when they were pregnant or had cubs. The noise during the exposures varied from 85 to 121 dB (L(AFmax)). Vixens (45 primiparous and 34 multiparous) on a farm without flight action acted as controls. Cubs were counted 1, 3, 7, 14 and 49 days postpartum and at the beginning of July. Litter size (cubs per whelped vixen), reproductive performance (cubs per mated vixen) and cub losses (lost cubs per whelped vixen) were analyzed from both experimental farms (A and C). The flight action had no effect on reproductive success. Reproductive performance in primiparous vixens was 4.2+/-3.8 and 4.3+/-3.6 cubs (ns, Mann-Whitney U-test) in the control and aviation group, respectively, while in multiparous vixens the corresponding figures were 7.1+/-4.4 and 7.3+/-3.8 cubs (ns). In general, litter size declined from birth to weaning (in primiparous vixens from 8.1+/-3.8 to 5.4+/-3.2 cubs, and in multiparous from 9.7+/-3.8 to 7.2+/-3.8 cubs, P<0.001, GLM for repeated measures). The decline was greater in primiparous than in multiparous vixens (P<0.01). There were no differences in total cub losses between the experimental groups (ns). Accordingly, the present results show that exposure to severe and repeated aviation noise does not impair the reproductive success of farmed blue foxes.     

Metabolic and phylogenetic analysis of microbial communities during phytoremediation of soil contaminated with weathered hydrocarbons and heavy metals

In the current study, the microbial ecology of weathered hydrocarbon and heavy metal contaminated soil undergoing phytoremediation was studied. The relationship of functional diversity, measured as carbon source utilisation in Biolog plates and extracellular enzymatic activities, and genetic diversity of bacteria was evaluated. Denaturing gradient gel electrophoresis was used for community analyses at the species level. Bulk soil and rhizosphere soil from pine and poplar plantations were analysed separately to determine if the plant rhizosphere impacted hydrocarbon degradation. Prevailing microbial communities in the field site were both genetically and metabolically diverse. Furthermore, both tree rhizosphere and fertilisation affected the compositions of these communities and increased activities of extracellular aminopeptidases. In addition, the abundance of alkane hydroxylase and naphthalene dioxygenase genes in the communities was low, but the prevalence of these genes was increased by the addition of bioavailable hydrocarbons. Tree rhizosphere communities had greater hydrocarbon degradation potential than those of bulk soil. Hydrocarbon utilising communities were dominated generally by the species Ralstonia eutropha and bacteria belonging to the genus Burkholderia. Despite the presence of viable hydrocarbon-degrading microbiota, decomposition of hydrocarbons from weathered hydrocarbon contaminated soil over four years, regardless of the presence of vegetation, was low in unfertilised soil. Compost addition enhanced the removal of hydrocarbons.