Risk Perception and Risk-Taking Behaviour during Adolescence: The Influence of Personality and Gender

This study investigated the influence of personality characteristics and gender on adolescents’ perception of risk and their risk-taking behaviour. Male and female participants (157 females: 116 males, aged 13–20) completed self-report measures on risk perception, risk-taking and personality. Male participants perceived behaviours as less risky, reportedly took more risks, were less sensitive to negative outcomes and less socially anxious than female participants. Path analysis identified a model in which age, behavioural inhibition and impulsiveness directly influenced risk perception, while age, social anxiety, impulsiveness, sensitivity to reward, behavioural inhibition and risk perception itself were directly or indirectly associated with risk-taking behaviour. Age and behavioural inhibition had direct relationships with social anxiety, and reward sensitivity was associated with impulsiveness. The model was representative for the whole sample and male and female groups separately. The observed relationship between age and social anxiety and the influence this may have on risk-taking behaviour could be key for reducing adolescent risk-taking behaviour. Even though adolescents may understand the riskiness of their behaviour and estimate their vulnerability to risk at a similar level to adults, factors such as anxiety regarding social situations, sensitivity to reward and impulsiveness may exert their influence and make these individuals prone to taking risks. If these associations are proven causal, these factors are, and will continue to be, important targets in prevention and intervention efforts.     

Crystal structure of sarcoplasmic reticulum Ca2+-ATPase (SERCA) from bovine muscle

The SERCA pump, a membrane protein of about 110kDa, transports two Ca(2+) ions per ATP hydrolyzed from the cytoplasm to the lumen of the sarcoplasmic reticulum. In muscle cells, its ability to remove Ca(2+) from the cytosol induces relaxation. The transport mechanism employed by the enzyme from rabbit muscle has been extensively studied, and several crystal structures representing different conformational states are available. However, no structure of the pump from other sources is known. In this paper we describe the crystal structure of the bovine enzyme, crystallized in the E1 conformation and determined at 2.9? resolution. The overall molecular model is very similar to that of the rabbit enzyme, as expected by the high amino acid sequence identity. Nevertheless, the bovine enzyme has reduced catalytic activity with respect to the rabbit enzyme. Subtle structural modifications, in particular in the region of the long loop that protrudes into the SR lumen connecting transmembrane α-helices M7 and M8, may explain the difference.     

Bcs1p can rescue a large and productive cytochrome bc1 complex assembly intermediate in the inner membrane of yeast mitochondria

The yeast cytochrome bc₁ complex, a component of the mitochondrial respiratory chain, is composed of ten distinct protein subunits. In the assembly of the bc₁ complex, some ancillary proteins, such as the chaperone Bcs1p, are actively involved. The deletion of the nuclear gene encoding this chaperone caused the arrest of the bc₁ assembly and the formation of a functionally inactive bc₁ core structure of about 500-kDa. This immature bc₁ core structure could represent, on the one hand, a true assembly intermediate or, on the other hand, a degradation product and/or an incorrect product of assembly. The experiments here reported show that the gradual expression of Bcs1p in the yeast strain lacking this protein was progressively able to rescue the bc₁ core structure leading to the formation of the functional homodimeric bc₁ complex. Following Bcs1p expression, the mature bc₁ complex was also progressively converted into two supercomplexes with the cytochrome c oxidase complex. The capability of restoring the bc₁ complex and the supercomplexes was also possessed by the mutated yeast R81C Bcsp1. Notably, in the human ortholog BCS1L, the corresponding point mutation (R45C) was instead the cause of a severe bc₁ complex deficiency. Differently from the yeast R81C Bcs1p, two other mutated Bcs1p's (K192P and F401I) were unable to recover the bc₁ core structure in yeast. This study identifies for the first time a productive assembly intermediate of the yeast bc₁ complex and gives new insights into the molecular mechanisms involved in the last steps of bc₁ assembly.     

Change in Body Size and Mortality: Results from the Melbourne Collaborative Cohort Study

Background

The association between change in weight or body mass index, and mortality is widely reported, however, both measures fail to account for fat distribution. Change in waist circumference, a measure of central adiposity, in relation to mortality has not been studied extensively.

Methods

We investigated the association between mortality and changes in directly measured waist circumference, hips circumference and weight from baseline (1990–1994) to wave 2 (2003–2007) in a prospective cohort study of people aged 40–69 years at baseline. Cox regression, with age as the time metric and follow-up starting at wave 2, adjusted for confounding variables, was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for change in body size in relation to mortality from all causes, cardiovascular disease and cancer.

Results

There were 1465 deaths (109 cancer, 242 cardiovascular disease) identified during an average 7.7 years of follow-up from 21 298 participants. Compared to minimal increase in body size, loss of waist circumference (HR: 1.26; 95% CI: 1.09–1.47), weight (1.80; 1.54–2.11), or hips circumference (1.35; 1.15–1.57) were associated with an increased risk of all-cause mortality, particularly for older adults. Weight loss was associated with cardiovascular disease mortality (2.40; 1.57–3.65) but change in body size was not associated with obesity-related cancer mortality.

Conclusion

This study confirms the association between weight loss and increased mortality from all-causes for older adults. Based on evidence from observational cohort studies, weight stability may be the recommended option for most adults, especially older adults.     

DNA sequence analysis of point mutations in traA, the F pilin gene, reveal two domains involved in F-specific bacteriophage attachment

Summary Six missense point mutations in traA (WPFL43,44,45,46,47 and 51), the gene encoding F pilin in the transfer region of the F plasmid, have been characterized for their effect on the transfer ability, bacteriophage (R17, QB and fl) sensitivity and levels of piliation expressed by the plasmid. The sequence analysis of the first five of these mutations revealed two domains in the F pilin subunit exposed on the surface of the F pilus which mediate phage attachment. These two domains include residues 14–17 (approximately) and the last few residues at the carboxy-terminus of the pilin protein. One of these mutants had a pleiotropic affect on pilus function and was thought to have affected pilus assembly. The sixthe point mutant (WPFL51), previously thought to be in traA, was complemented by chimeric plasmids carrying the traG gene of the F transfer region, which may be involved in the acetylation of the pilin subunit. A traA nonsense mutant (JCFL1) carried an amber mutation near the amino-terminus which is well suppressed in SuI⁺ (supD) and SuIII⁺ (supF) strains. Neither the antigenicity of the pilin nor the efficiency of plating of F-specific bacteriophages were affected when this plasmid was harbored by either suppressor strain. A second amber mutant (JCFL25) which is not suppressible, carried its mutation in the codon for the single tryptophan in F pilin, suggesting that this residue is important in subunit interactions during pilus assembly. Two other point mutants (JCFL32 and 44) carried missense mutations in the leader sequence (positions 9 and 13) which affected the number of pili per cell presumably by altering the processing of propilin to pilin.     

Hx, a novel fluorescent, minor groove and sequence specific recognition element: design, synthesis, and DNA binding properties of p-anisylbenzimidazole-imidazole/pyrrole-containing polyamides

With the aim of incorporating a recognition element that acts as a fluorescent probe upon binding to DNA, three novel pyrrole (P) and imidazole (I)-containing polyamides were synthesized. The compounds contain a p-anisylbenzimidazolecarboxamido (Hx) moiety attached to a PP, IP, or PI unit, giving compounds HxPP (2), HxIP (3), and HxPI (4), respectively. These fluorescent hybrids were tested against their complementary nonfluorescent, non-formamido tetraamide counterparts, namely, PPPP (5), PPIP (6), and PPPI (7) (cognate sequences 5'-AAATTT-3', 5'-ATCGAT-3', and 5'-ACATGT-3', respectively). The binding affinities for both series of polyamides for their cognate and noncognate sequences were ascertained by surface plasmon resonance (SPR) studies, which revealed that the Hx-containing polyamides gave binding constants in the 10(6) M(-1) range while little binding was observed for the noncognates. The binding data were further compared to the corresponding and previously reported formamido-triamides f-PPP (8), f-PIP (9), and f-PPI (10). DNase I footprinting studies provided additional evidence that the Hx moiety behaved similarly to two consecutive pyrroles (PP found in 5-7), which also behaved like a formamido-pyrrole (f-P) unit found in distamycin and many formamido-triamides, including 8-10. The biophysical characterization of polyamides 2-7 on their binding to the abovementioned DNA sequences was determined using thermal melts (ΔT(M)), circular dichroism (CD), and isothermal titration calorimetry (ITC) studies. Density functional calculations (B3LYP) provided a theoretical framework that explains the similarity between PP and Hx on the basis of molecular electrostatic surfaces and dipole moments. Furthermore, emission studies on polyamides 2 and 3 showed that upon excitation at 322 nm binding to their respective cognate sequences resulted in an increase in fluorescence at 370 nm. These low molecular weight polyamides show promise for use as probes for monitoring DNA recognition processes in cells.     

Anaerobic Ammonium-Oxidizing Bacteria: Unique Microorganisms with Exceptional Properties

Summary: Anaerobic ammonium-oxidizing (anammox) bacteria defy many microbiological concepts and share numerous properties with both eukaryotes and archaea. Among their most intriguing characteristics are their compartmentalized cell plan and archaeon-like cell wall. Here we review our current knowledge about anammox cell biology. The anammox cell is divided into three separate compartments by bilayer membranes. The anammox cell consists of (from outside to inside) the cell wall, paryphoplasm, riboplasm, and anammoxosome. Not much is known about the composition or function of both the anammox cell wall and the paryphoplasm compartment. The cell wall is proposed to be proteinaceous and to lack both peptidoglycan and an outer membrane typical of Gram-negative bacteria. The function of the paryphoplasm is unknown, but it contains the cell division ring. The riboplasm resembles the standard cytoplasmic compartment of other bacteria; it contains ribosomes and the nucleoid. The anammoxosome occupies most of the cell volume and is a so-called “prokaryotic organelle” analogous to the eukaryotic mitochondrion. This is the site where the anammox reaction takes place, coupled over the curved anammoxosome membrane, possibly giving rise to a proton motive force and subsequent ATP synthesis. With these unique properties, anammox bacteria are food for thought concerning the early evolution of the domains Bacteria, Archaea, and Eukarya.     

Desarrollo global del niño: más allá de la suplementación farmacológica con yodo

Iodine deficiency is a factor that may compromise child development, but is not the only one. Other health determinants, some of them outside the healthcare system, are able to influence development. Fighting iodine deficiency may be a pragmatic and useful strategy if it is found to be not maleficent, beneficial to health, and cost-effective, and does not make us lose the notion that child development goes beyond psychomotor or cognitive performance. This article analyzes such constraints from a critical point of view.