Variability in the Effect of 5-HTTLPR on Depression in a Large European Population: The Role of Age,Symptom Profile,Type and Intensity of Life Stressors

Background

Although 5-HTTLPR has been shown to influence the risk of life stress-induced depression in the majority of studies, others have produced contradictory results, possibly due to weak effects and/or sample heterogeneity.

Methods

In the present study we investigated how age, type and intensity of life-stressors modulate the effect of 5-HTTLPR on depression and anxiety in a European population cohort of over 2300 subjects. Recent negative life events (RLE), childhood adversity (CHA), lifetime depression, Brief Symptoms Inventory (BSI) depression and anxiety scores were determined in each subject. Besides traditional statistical analysis we calculated Bayesian effect strength and relevance of 5-HTTLPR genotypes in specified models.

Results

The short (s) low expressing allele showed association with increased risk of depression related phenotypes, but all nominally significant effects would turn to non-significant after correction for multiple testing in the traditional analysis. Bayesian effect strength and relevance analysis, however, confirmed the role of 5-HTTLPR. Regarding current (BSI) and lifetime depression 5-HTTLPR-by-RLE interactions were confirmed. Main effect, with other words direct association, was supported with BSI anxiety. With more frequent RLE the prevalence or symptoms of depression increased in ss carriers. Although CHA failed to show an interaction with 5-HTTLPR, in young subjects CHA sensitized towards the depression promoting effect of even mild RLE. Furthermore, the direct association of anxiety with the s allele was driven by young (≤30) individuals.

Limitations

Our study is cross-sectional and applies self-report questionnaires.

Conclusions

Albeit 5-HTTLPR has only weak/moderate effects, the s allele is directly associated with anxiety and modulates development of depression in homogeneous subgroups.     

Ca2+ -Dependent Release from Rat Brain of Cannabinoid Receptor Binding Activity

As a result of the identification, pharmacological characterization, and localization of the cannabinoid receptor in the CNS, the existence of an endogenous ligand for this receptor can be hypothesized. Following the premise that such a substance could have the properties of a neuromodulator being stored in intracellular vesicles, we tested the ability of increased intracellular Ca2+ levels to stimulate release. We demonstrate here that the Ca2+ ionophore A23187 can induce release of cannabinoid-like binding activity in the presence but not in the absence of Ca2+. The effect of A23187 was maximal at 1.2 microM, consistent with vesicular release. It was necessary to increase the concentration of extracellular free Ca2+ to greater than 60 nM to evoke release. The released cannabinoid-like binding activity displaced [3H]CP-55940 binding to cannabinoid receptors in rat synaptosomal membranes in a concentration-dependent manner. This is the first report of a substance present endogenously in brain that can be released in a Ca(2+)-dependent manner and that binds to the cannabinoid receptor.     

Global regulation of alternative splicing during myogenic differentiation

Recent genome-wide analyses have elucidated the extent of alternative splicing (AS) in mammals, often focusing on comparisons of splice isoforms between differentiated tissues. However, regulated splicing changes are likely to be important in biological transitions such as cellular differentiation, or response to environmental stimuli. To assess the extent and significance of AS in myogenesis, we used splicing-sensitive microarray analysis of differentiating C2C12 myoblasts. We identified 95 AS events that undergo robust splicing transitions during C2C12 differentiation. More than half of the splicing transitions are conserved during differentiation of avian myoblasts, suggesting the products and timing of transitions are functionally significant. The majority of splicing transitions during C2C12 differentiation fall into four temporal patterns and were dependent on the myogenic program, suggesting that they are integral components of myogenic differentiation. Computational analyses revealed enrichment of many sequence motifs within the upstream and downstream intronic regions near the alternatively spliced regions corresponding to binding sites of splicing regulators. Western analyses demonstrated that several splicing regulators undergo dynamic changes in nuclear abundance during differentiation. These findings show that within a developmental context, AS is a highly regulated and conserved process, suggesting a major role for AS regulation in myogenic differentiation.     

Electrochemical Characteristics of Nitroheterocyclic Compounds of Biological Interest. VIII Stability of Nitro Radical Anions from Cyclic Voltammetric Studies

The stability of the one electron addition product of four biologically important nitroheterocyclic compounds has been examined electrochemically. Using cyclic voltammetry the tendency of the nitro radical anion to undergo disproportionation was studied by two methods of analysis. The first was based on determining the voltammetric time-constant required for half of the reduction product, RNO₂, to react further. The second concerned the minimum volume of dimethylformamide which had to be added to the aqueous electrolytic medium to give a specific cyclic voltammetric response. Both methods were found to compare well with the results obtained for RNO₂T stabilities using a theoretically derived procedure for a second order reaction following a charge-transfer step. The use of these alternative approaches for quantifying the reactivity of reduction products is discussed. The time-constant method in particular may be useful in studying complex reaction pathways.     

Local and global cerebral blood flow and glucose utilization in the α-galactosidase A knockout mouse model of Fabry disease

Fabry disease is an X-linked lysosomal disorder characterized by deficient alpha-galactosidase A activity and intracellular accumulations of glycosphingolipids, mainly globotriaosylceramide (Gb3). Clinically, patients occasionally present CNS dysfunction. To examine the pathophysiology underlying brain dysfunction, we examined glucose utilization (CMR(glc)) and cerebral blood flow (CBF) globally and locally in 18 brain structures in the alpha-galactosidase A gene knockout mouse. Global CMR(glc) was statistically significantly reduced by 22% in Fabry mice (p < 0.01). All 18 structures showed decreases in local CMR(glc) ranging from 14% to 33%. The decreases in all structures of the diencephalon, caudate-putamen, brain stem, and cerebellar cortex were statistically significant (p < 0.05). Global cerebral blood flow (CBF) and local CBF measured in the same 18 structures were lower in Fabry mice than in control mice, but none statistically significantly. Histological examination of brain revealed no cerebral infarcts but abundant Gb3 deposits in the walls of the cerebral vessels with neuronal deposits localized to the medulla oblongata. These results indicate an impairment in cerebral energy metabolism in the Fabry mice, but one not necessarily due to circulatory insufficiency.     

High-sensitivity stable-isotope probing by a quantitative terminal restriction fragment length polymorphism protocol

Stable-isotope probing (SIP) has proved a valuable cultivation-independent tool for linking specific microbial populations to selected functions in various natural and engineered systems. However, application of SIP to microbial populations with relatively minor buoyant density increases, such as populations that utilize compounds as a nitrogen source, results in reduced resolution of labeled populations. We therefore developed a tandem quantitative PCR (qPCR)-TRFLP (terminal restriction fragment length polymorphism) protocol that improves resolution of detection by quantifying specific taxonomic groups in gradient fractions. This method combines well-controlled amplification with TRFLP analysis to quantify relative taxon abundance in amplicon pools of FAM-labeled PCR products, using the intercalating dye EvaGreen to monitor amplification. Method accuracy was evaluated using mixtures of cloned 16S rRNA genes, DNA extracted from low- and high-G+C bacterial isolates (Escherichia coli, Rhodococcus, Variovorax, and Microbacterium), and DNA from soil microcosms amended with known amounts of genomic DNA from bacterial isolates. Improved resolution of minor shifts in buoyant density relative to TRFLP analysis alone was confirmed using well-controlled SIP analyses.     

The specific mitochondrial DNA polymorphism found in Klinefelter's syndrome

Hypervariable segments of mitochondrial DNA (mtDNA) (HV1 and HV2) were analyzed in Klinefelter's syndrome and compared to normal population data. One pair of samples consisting of a Japanese mother and affected son with Klinefelter's syndrome (involved in a criminal case), and seven unrelated DNA samples from Caucasian Klinefelter males (two involved in criminal cases and five diagnosed) were collected in Japan and the United States. The diagnosis of Klinefelter's syndrome was established previously by multiplex XY-STR typing detecting two X alleles and one Y allele in the samples. Haplotype analysis of the mtDNA sequence in Klinefelter males was found to be identical, unique, and specific, as it was not found in the normal population. Astonishingly, family data exhibited that the haplotype of the mtDNA in the son was apparently different from the mother's, suggesting that the mtDNA of Klinefelter male would not be inherited from mother to son. Our data indicate that possible interaction of the sex chromosome and the mtDNA exists, and suggests that the specific mtDNA haplotype could cause the abnormal cell to fertilize and reproduce itself.     

Novel Clostridium thermocellum Type I Cohesin-Dockerin Complexes Reveal a Single Binding Mode

Protein-protein interactions play a pivotal role in a large number of biological processes exemplified by the assembly of the cellulosome. Integration of cellulosomal components occurs through the binding of type I cohesin modules located in a non-catalytic molecular scaffold to type I dockerin modules located at the C terminus of cellulosomal enzymes. The majority of type I dockerins display internal symmetry reflected by the presence of two essentially identical cohesin-binding surfaces. Here we report the crystal structures of two novel Clostridium thermocellum type I cohesin-dockerin complexes (CohOlpC-Doc124A and CohOlpA-Doc918). The data revealed that the two dockerins, Doc918 and Doc124A, are unusual because they lack the structural symmetry required to support a dual binding mode. Thus, in both cases, cohesin recognition is dominated by residues located at positions 11, 12, and 19 of one of the dockerin binding surfaces. The alternative binding mode is not possible (Doc918) or highly limited (Doc124A) because residues that assume the critical interacting positions, when dockerins are reoriented by 180°, make steric clashes with the cohesin. In common with a third dockerin (Doc258) that also presents a single binding mode, Doc124A directs the appended cellulase, Cel124A, to the surface of C. thermocellum and not to cellulosomes because it binds preferentially to type I cohesins located at the cell envelope. Although there are a few exceptions, such as Doc918 described here, these data suggest that there is considerable selective pressure for the evolution of a dual binding mode in type I dockerins that direct enzymes into cellulosomes.     

Energetic modelling: A comparison of the different approaches used in seabirds

Studying energetics of marine top predators is essential to understand their role within food-webs and mechanisms associated with their survival and population dynamics. Several methods exist to estimate energy expenditure in captive and free-ranging animals. However, most of them are difficult to implement, restrained to specific periods, and are consequently inappropriate for seabirds. Supplementary and complementary approaches are therefore needed, and the use of modelling appears as an excellent option allowing energetic studies when field data collection is challenging. Currently three main energetics models are used, with various degrees of complexity and accuracy: allometric equations, time–energy-budget analyses and thermodynamic models. However, a comparison of their practicability and accuracy was still lacking. Here, we present an overview of these 3 model types, their characteristics, advantages and disadvantages, and areas of application in seabirds. We then investigate their accuracy by using them in parallel for the same dataset, and by comparing outputs with direct measurements (doubly-labelled water technique). We show that, when detailed data are available, time–energy–budget analysis is the best model to accurately predict seabird energy expenditures. Conversely, thermodynamic modelling allows reasonably accurate calculations when field data are scarce, and is therefore ideal to study energetics during the inter-breeding season.