A subgroup of light-driven sodium pumps with an additional Schiff base counterion.

Light-driven sodium pumps (NaRs) are unique ion-transporting microbial rhodopsins. The major group of NaRs is characterized by an NDQ motif and has two aspartic acid residues in the central region essential for sodium transport. Here we identify a subgroup of the NDQ rhodopsins bearing an additional glutamic acid residue in the close vicinity to the retinal Schiff base. We thoroughly characterize a member of this subgroup, namely the protein ErNaR from Erythrobacter sp. HL-111 and show that the additional glutamic acid results in almost complete loss of pH sensitivity for sodium-pumping activity, which is in contrast to previously studied NaRs. ErNaR is capable of transporting sodium efficiently even at acidic pH levels. X-ray crystallography and single particle cryo-electron microscopy reveal that the additional glutamic acid residue mediates the connection between the other two Schiff base counterions and strongly interacts with the aspartic acid of the characteristic NDQ motif. Hence, it reduces its pKa. Our findings shed light on a subgroup of NaRs and might serve as a basis for their rational optimization for optogenetics.

Evidence for a vibrational phase-dependent isotope effect on the photochemistry of vision.

Vibronic coupling is key to efficient energy flow in molecular systems and a critical component of most mechanisms invoking quantum effects in biological processes. Despite increasing evidence for coherent coupling of electronic states being mediated by vibrational motion, it is not clear how and to what degree properties associated with vibrational coherence such as phase and coupling of atomic motion can impact the efficiency of light-induced processes under natural, incoherent illumination. Here, we show that deuteration of the H11-C11=C12-H12 double-bond of the 11-cis retinal chromophore in the visual pigment rhodopsin significantly and unexpectedly alters the photoisomerization yield while inducing smaller changes in the ultrafast isomerization dynamics assignable to known isotope effects. Combination of these results with non-adiabatic molecular dynamics simulations reveals a vibrational phase-dependent isotope effect that we suggest is an intrinsic attribute of vibronically coherent photochemical processes.

Personality traits and cancer survival: a Danish cohort study.

We conducted a population-based prospective cohort study in Denmark to investigate associations between the personality traits and cancer survival. Between 1976 and 1977, 1020 residents of the Copenhagen County completed a questionnaire eliciting information on personality traits and various health habits. The personality traits extraversion and neuroticism were measured using the short form of the Eysenck Personality Inventory. Follow-up in the Danish Cancer Registry for 1976-2002 revealed 189 incidents of primary cancer and follow-up for death from the date of the cancer diagnosis until 2005 revealed 82 deaths from all-cause in this group. A Cox proportional-hazards model was used to estimate the hazard ratios (HRs) of death from all-cause according to extraversion and neuroticism adjusting for potential confounding factors. A significant association was found between neuroticism and risk of death (HR, 2.3 (95% CI=1.1-4.7); Linear trend P=0.04) but not between extraversion and risk of death (HR, 0.9 (0.4-1.7); Linear trend P=0.34). Similar results were found when using cancer-related death. Stratification by gender revealed a strong positive association between neuroticism and the risk of death among women (Linear trend P=0.03). This study showed that neuroticism is negatively [corrected] associated with cancer survival. Further research on neuroticism and cancer survival is needed.

Mind and cancer. do psychological factors cause cancer?

We have reviewed the evidence for an association between major life events, depression and personality factors and the risk for cancer. We identified and included only those prospective or retrospective studies in which the psychological variable was collected independently of the outcome. The evidence failed to support the hypothesis that major life events are a risk factor for cancer. The evidence was inconsistent for both depression and personality factors. Chance, bias or confounding may explain this result, as many of the studies had methodological weaknesses. The generally weak associations found, the inconsistency of the results, the unresolved underlying biological mechanism and equivocal findings of dose-response relationships prevent a conclusion that psychological factors are established risk factors. However, certain intriguing findings warrant further studies, which must, however, be well conducted and large and include detailed information on confounders.

Extroversion and neuroticism and the associated risk of cancer: A Danish cohort study.

The authors have investigated the effect of personality, as measured with the Eysenck Personality Inventory, on the incidence of cancer among 1,031 persons participating in a Danish health survey in 1976-1977 and followed up for 20 years. They thereby accrued a total of 19,993 person-years. The expected number of cancer cases was estimated on the basis of age-, sex-, and site-specific incidence rates in Copenhagen County, DENMARK: Overall, 113 malignancies were observed among the cohort members between the date of interview and December 31, 1996. Since 114.3 were expected from county incidence rates, the standardized incidence ratio was 0.99 (95% confidence interval: 0.81, 1.19). No statistically significant deviation of the relative risk from unity was seen for any measure of personality, and no excess risk was seen for any particular type of cancer. A regression model, in which adjustment was made for age, sex, calendar period, alcohol consumption, tobacco smoking, psychiatric illness as rated by the interviewing doctor, marital status, and social class, showed no excess risk of cancer among persons considered to be in medium- or high-risk groups according to the Eysenck Personality INVENTORY: The authors' data provide no support for the hypothesis of an association between personality and the risk of cancer.