Early environment and neurobehavioral development predict adult temperament clusters

Background

Investigation of the environmental influences on human behavioral phenotypes is important for our understanding of the causation of psychiatric disorders. However, there are complexities associated with the assessment of environmental influences on behavior.

Methods/Principal Findings

We conducted a series of analyses using a prospective, longitudinal study of a nationally representative birth cohort from Finland (the Northern Finland 1966 Birth Cohort). Participants included a total of 3,761 male and female cohort members who were living in Finland at the age of 16 years and who had complete temperament scores. Our initial analyses (Wessman et al., in press) provide evidence in support of four stable and robust temperament clusters. Using these temperament clusters, as well as independent temperament dimensions for comparison, we conducted a data-driven analysis to assess the influence of a broad set of life course measures, assessed pre-natally, in infancy, and during adolescence, on adult temperament.

Results

Measures of early environment, neurobehavioral development, and adolescent behavior significantly predict adult temperament, classified by both cluster membership and temperament dimensions. Specifically, our results suggest that a relatively consistent set of life course measures are associated with adult temperament profiles, including maternal education, characteristics of the family’s location and residence, adolescent academic performance, and adolescent smoking.

Conclusions

Our finding that a consistent set of life course measures predict temperament clusters indicate that these clusters represent distinct developmental temperament trajectories and that information about a subset of life course measures has implications for adult health outcomes.     

Telomeric DNA damage is irreparable and causes persistent DNA-damage-response activation

The DNA-damage response (DDR) arrests cell-cycle progression until damage is removed. DNA-damage-induced cellular senescence is associated with persistent DDR. The molecular bases that distinguish transient from persistent DDR are unknown. Here we show that a large fraction of exogenously induced persistent DDR markers is associated with telomeric DNA in cultured cells and mammalian tissues. In yeast, a chromosomal DNA double-strand break next to a telomeric sequence resists repair and impairs DNA ligase 4 recruitment. In mammalian cells, ectopic localization of telomeric factor TRF2 next to a double-strand break induces persistent DNA damage and DDR. Linear, but not circular, telomeric DNA or scrambled DNA induces a prolonged checkpoint in normal cells. In terminally differentiated tissues of old primates, DDR markers accumulate at telomeres that are not critically short. We propose that linear genomes are not uniformly reparable and that telomeric DNA tracts, if damaged, are irreparable and trigger persistent DDR and cellular senescence.     

Dioxin induces genomic instability in mouse embryonic fibroblasts

Ionizing radiation and certain other exposures have been shown to induce genomic instability (GI), i.e., delayed genetic damage observed many cell generations later in the progeny of the exposed cells. The aim of this study was to investigate induction of GI by a nongenotoxic carcinogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Mouse embryonic fibroblasts (C3H10T1/2) were exposed to 1, 10 or 100 nM TCDD for 2 days. Micronuclei (MN) and expression of selected cancer-related genes were assayed both immediately and at a delayed point in time (8 days). For comparison, similar experiments were done with cadmium, a known genotoxic agent. TCDD treatment induced an elevated frequency of MN at 8 days, but not directly after the exposure. TCDD-induced alterations in gene expression were also mostly delayed, with more changes observed at 8 days than at 2 days. Exposure to cadmium produced an opposite pattern of responses, with pronounced effects immediately after exposure but no increase in MN and few gene expression changes at 8 days. Although all responses to TCDD alone were delayed, menadione-induced DNA damage (measured by the Comet assay), was found to be increased directly after a 2-day TCDD exposure, indicating that the stability of the genome was compromised already at this time point. The results suggested a flat dose-response relationship consistent with dose-response data reported for radiation-induced GI. These findings indicate that TCDD, although not directly genotoxic, induces GI, which is associated with impaired DNA damage response.     

In vitro functional and immunomodulatory properties of the Lactobacillus helveticus MIMLh5-Streptococcus salivarius ST3 association that are relevant to the development of a pharyngeal probiotic product

The use of proper bacterial strains as probiotics for the pharyngeal mucosa is a potential prophylactic strategy for upper respiratory tract infections. In this context, we characterized in vitro the functional and immunomodulatory properties of the strains Lactobacillus helveticus MIMLh5 and Streptococcus salivarius ST3 that were selected during previous investigations as promising pharyngeal probiotics. In this study, we demonstrated in vitro that strains MIMLh5 and ST3, alone and in combination, can efficiently adhere to pharyngeal epithelial cells, antagonize Streptococcus pyogenes, and modulate host innate immunity by inducing potentially protective effects. In particular, we found that the strains MIMLh5 and ST3 activate U937 human macrophages by significantly inducing the expression of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). Nonetheless, the induction of the anti-inflammatory interleukin-10 (IL-10) by MIMLh5 or ST3 was never lower than that of TNF-α, suggesting that these bacteria can potentially exert a regulatory rather than a proinflammatory effect. We also found that the strains MIMLh5 and ST3 induce cyclooxygenase 2 (COX-2) expression and demonstrated that toll-like receptor 2 (TLR-2) participates in the recognition of the strains MIMLh5 and ST3 by U937 cells. Finally, we observed that these microorganisms grow efficiently when cocultured in milk, suggesting that the preparation of a milk-based fermented product containing both MIMLh5 and ST3 can be a practical solution for the administration of these bacteria. In conclusion, we propose the combined use of L. helveticus MIMLh5 and S. salivarius ST3 for the preparation of novel products that display probiotic properties for the pharyngeal mucosa.     

Photoperiodic regulation of cold tolerance and expression levels of regucalcin gene in Drosophila montana

Temperature-induced plasticity of cold tolerance has been reported in many insect species, but cold tolerance can also be affected by changes in day (or night) length. In the present study we elucidate the direct and indirect effects of photoperiod on the cold tolerance of females of two Drosophila montana strains--one which possesses a robust photoperiodic diapause and another which does not. In the diapause-strain the time needed for recovery from chill coma showed a positive correlation with day length, but diapause itself played only a minor role in photoperiodic acclimation. The strain that was not able to enter to diapause as a response to day length also lacked photoperiodic cold acclimation ability indicating that this strain has deficiencies in its photoperiodic time measurement system. In the diapause-strain, the expression level of regucalcin gene was more than two times higher in diapausing than in non-diapausing females maintained in a single photoperiod, but day length per se did not cause significant changes in expression levels of this gene in either of the strains. In the non-diapausing strain this gene showed no expression changes in any comparison. Overall, the study shows that a decrease in day length can induce cold acclimation in D. montana, while changes in regucalcin expression are linked with photoperiodic diapause.     

Mechanism for translocation of fluoroquinolones across lipid membranes

Classical atom-scale molecular dynamics simulations, constrained free energy calculations, and quantum mechanical (QM) calculations are employed to study the diffusive translocation of ciprofloxacin (CPFX) across lipid membranes. CPFX is considered here as a representative of the fluoroquinolone antibiotics class. Neutral and zwitterionic CPFX coexist at physiological pH, with the latter being predominant. Simulations reveal that only the neutral form permeates the bilayer, and it does so through a novel mechanism that involves dissolution of concerted stacks of zwitterionic ciprofloxacins. Subsequent QM analysis of the observed molecular stacking shows the important role of partial charge neutralization in the stacks, highlighting how the zwitterionic form of the drug is neutralized for translocation. The findings propose a translocation mechanism in which zwitterionic CPFX molecules approach the membrane in stacks, but they diffuse through the membrane as neutral CPFX monomers due to intermolecular transfer of protons favored by partial solvation loss. The mechanism is expected to be of importance in the permeation and translocation of a variety of ampholitic drugs with stacking tendencies.     

Selective cross‐linking of coinciding protein assemblies by in‐gel cross‐linking mass spectrometry

Cross‐linking mass spectrometry has developed into an important method to study protein structures and interactions. The in‐solution cross‐linking workflows involve time and sample consuming steps and do not provide sensible solutions for differentiating cross‐links obtained from co‐occurring protein oligomers, complexes, or conformers. Here we developed a cross‐linking workflow combining blue native PAGE with in‐gel cross‐linking mass spectrometry (IGX‐MS). This workflow circumvents steps, such as buffer exchange and cross‐linker concentration optimization. Additionally, IGX‐MS enables the parallel analysis of co‐occurring protein complexes using only small amounts of sample. Another benefit of IGX‐MS, demonstrated by experiments on GroEL and purified bovine heart mitochondria, is the substantial reduction of undesired over‐length cross‐links compared to in‐solution cross‐linking. We next used IGX‐MS to investigate the complement components C5, C6, and their hetero‐dimeric C5b6 complex. The obtained cross‐links were used to generate a refined structural model of the complement component C6, resembling C6 in its inactivated state. This finding shows that IGX‐MS can provide new insights into the initial stages of the terminal complement pathway.     

Characterization of the polyphenolic composition of purple loosestrife (Lythrum salicaria)

Phenolic compounds of purple loosestrife (Lythrum salicaria L.) were analysed by the use of liquid chromatography-mass spectrometry (LC/MS) equipped with atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI). The presence of vitexin and orientin as well as their isomers, isovitexin and isoorientin, were confirmed using ion trap multiple stage LC/MS3 analysis. Several phenolic acids and tannins were also detected. Ellagitannins, vescalagin and pedunculagin, are reported from the plant for the first time.