Proteomics and lipids of lipoproteins isolated at low salt concentrations in D2O/sucrose or in KBr

There is much interest in the significance of apolipoproteins and proteins that are noncovalently associated with lipoproteins. It is possible that the high ionic strength used for isolation of lipoproteins with KBr and NaI could alter the pattern of associated exchangeable proteins. Here we describe lipoprotein classes fractionation from up to 0.5 ml of serum or plasma with buffers of physiological ionic strength and pH prepared with deuterium oxide (D(2)O) and sucrose. An advantage of the D(2)O/sucrose procedure was that the lipoproteins could be directly analyzed by the techniques described without need for desalting. We compared the isolated lipoproteins with those obtained using ultracentrifugation in KBr from the same plasma pool. Electrophoretic homogeneity of the lipoproteins was very similar using the two methods, as well as their lipid composition evaluated by HPLC. Two-dimensional electrophoresis and surface-enhanced laser adsorption/ionization time-of-flight mass spectrometry indicated that the patterns of exchangeable proteins of VLDL isolated using with the two procedures were very similar. However, significant differences were found in the profiles of LDL and HDL, indicating that the D(2)O/sucrose method allowed a more complete characterization of its exchangeable apolipoproteins and proteins.     

Independence and interdependence of Dif and Frz chemosensory pathways in Myxococcus xanthus chemotaxis

Dif and Frz, two Myxococcus xanthus chemosensory pathways, are required in phosphatidylethanolamine (PE) chemotaxis for excitation and adaptation respectively. DifA and FrzCD, the homologues of methyl-accepting chemoreceptors in the two pathways, were examined for methylation in the context of chemotaxis and inter-pathway interactions. Evidence indicates that DifA may not undergo methylation, but signals transmitting through DifA do modulate FrzCD methylation. Results also revealed that M. xanthus possesses Dif-dependent and Dif-independent PE-sensing mechanisms. Previous studies showed that FrzCD methylation is decreased by negative chemostimuli but increased by attractants such as PE. Results here demonstrate that the Dif-dependent sensory mechanism suppresses the increase in FrzCD methylation in attractant response and elevates FrzCD methylation upon negative stimulation. In other words, FrzCD methylation is governed by opposing forces from Dif-dependent and Dif-independent sensing mechanisms. We propose that the Dif-independent but Frz-dependent PE sensing leads to increases in FrzCD methylation and subsequent adaptation, while the Dif-dependent PE signalling suppresses or diminishes the increase in FrzCD methylation to decelerate or delay adaptation. We contend that these antagonistic interactions are crucial for effective chemotaxis in this gliding bacterium to ensure that adaptation does not occur too quickly relative to the slow speed of M. xanthus movement.     

DDB accumulates at DNA damage sites immediately after UV irradiation and directly stimulates nucleotide excision repair.

Damaged DNA-binding protein, DDB, is a heterodimer of p127 and p48 with a high specificity for binding to several types of DNA damage. Mutations in the p48 gene that cause the loss of DDB activity were found in a subset of xeroderma pigmentosum complementation group E (XP-E) patients and have linked to the deficiency in global genomic repair of cyclobutane pyrimidine dimers (CPDs) in these cells. Here we show that with a highly defined system of purified repair factors, DDB can greatly stimulate the excision reaction reconstituted with XPA, RPA, XPC.HR23B, TFIIH, XPF.ERCC1 and XPG, up to 17-fold for CPDs and approximately 2-fold for (6-4) photoproducts (6-4PPs), indicating that no additional factor is required for the stimulation by DDB. Transfection of the p48 cDNA into an SV40-transformed human cell line, WI38VA13, was found to enhance DDB activity and the in vivo removal of CPDs and 6-4PPs. Furthermore, the combined technique of recently developed micropore UV irradiation and immunostaining revealed that p48 (probably in the form of DDB heterodimer) accumulates at locally damaged DNA sites immediately after UV irradiation, and this accumulation is also observed in XP-A and XP-C cells expressing exogenous p48. These results suggest that DDB can rapidly translocate to the damaged DNA sites independent of functional XPA and XPC proteins and directly enhance the excision reaction by core repair factors.     

Vision and Eating Behavior

Objective: Eating behavior is influenced by internal and external factors. Vision is one part of the complex pattern of factors influencing the amount of food consumed during a meal. The aim of this study was to explore the impact of vision on the microstructure of eating behavior and the subjective motivation to eat. Research Methods and Procedures: Nine blind subjects and nine matched seeing control subjects consumed a standardized meal registered by VIKTOR, an eating monitor, measuring the microstructure of the eating behavior. The eating behavior of the control subjects was registered twice, with and without blindfold. Results: The eating behavior of the blind subjects did not differ from that of seeing control subjects. However, the eating behavior of seeing subjects eating with blindfold demonstrated a clear impact of vision on eating behavior. When blindfolded, subjects ate 22% less food (p < 0.05), had shorter meal durations (p < 0.05), and had less decelerated eating curves (p < 0.05). Despite a smaller amount of food consumed when blindfolded, the reported feeling of fullness was identical to that reported after the larger meal consumed without blindfold. Discussion: The importance of vision in regulating our eating behavior is further stressed in this study. Eating with a blindfold decreased the intake of food, without making subjects feel less full. Eating blindfolded, therefore, may force subjects to rely more on internal signals. These results might be used as an aid in the development of new treatment strategies for obese subjects.     

Effects of stress on human mating preferences: stressed individuals prefer dissimilar mates

Although humans usually prefer mates that resemble themselves, mating preferences can vary with context. Stress has been shown to alter mating preferences in animals, but the effects of stress on human mating preferences are unknown. Here, we investigated whether stress alters men''s preference for self-resembling mates. Participants first underwent a cold-pressor test (stress induction) or a control procedure. Then, participants viewed either neutral pictures or pictures of erotic female nudes whose facial characteristics were computer-modified to resemble either the participant or another participant, or were not modified, while startle eyeblink responses were elicited by noise probes. Erotic pictures were rated as being pleasant, and reduced startle magnitude compared with neutral pictures. In the control group, startle magnitude was smaller during foreground presentation of photographs of self-resembling female nudes compared with other-resembling female nudes and non-manipulated female nudes, indicating a higher approach motivation to self-resembling mates. In the stress group, startle magnitude was larger during foreground presentation of self-resembling female nudes compared with other-resembling female nudes and non-manipulated female nudes, indicating a higher approach motivation to dissimilar mates. Our findings show that stress affects human mating preferences: unstressed individuals showed the expected preference for similar mates, but stressed individuals seem to prefer dissimilar mates.     

Wind Farm Facilities in Germany Kill Noctule Bats from Near and Far

Over recent years, it became widely accepted that alternative, renewable energy may come at some risk for wildlife, for example, when wind turbines cause large numbers of bat fatalities. To better assess likely populations effects of wind turbine related wildlife fatalities, we studied the geographical origin of the most common bat species found dead below German wind turbines, the noctule bat (Nyctalus noctula). We measured stable isotope ratios of non-exchangeable hydrogen in fur keratin to separate migrants from local individuals, used a linear mixed-effects model to identify temporal, spatial and biological factors explaining the variance in measured stable isotope ratios and determined the geographical breeding provenance of killed migrants using isoscape origin models. We found that 72% of noctule bat casualties (n = 136) were of local origin, while 28% were long-distance migrants. These findings highlight that bat fatalities at German wind turbines may affect both local and distant populations. Our results indicated a sex and age-specific vulnerability of bats towards lethal accidents at turbines, i.e. a relatively high proportion of killed females were recorded among migratory individuals, whereas more juveniles than adults were recorded among killed bats of local origin. Migratory noctule bats were found to originate from distant populations in the Northeastern parts of Europe. The large catchment areas of German wind turbines and high vulnerability of female and juvenile noctule bats call for immediate action to reduce the negative cross-boundary effects of bat fatalities at wind turbines on local and distant populations. Further, our study highlights the importance of implementing effective mitigation measures and developing species and scale-specific conservation approaches on both national and international levels to protect source populations of bats. The efficacy of local compensatory measures appears doubtful, at least for migrant noctule bats, considering the large geographical catchment areas of German wind turbines for this species.     

Exposure of HeLa DNA polymerase alpha to protein kinase C affects its catalytic properties

Protein kinase C (Ca2+/phospholipid-dependent protein kinase) purified from rat brain or endogenous to cell-free extracts from HeLa cells stimulates, by a factor of 2-3, HeLa DNA polymerase alpha but not beta or gamma. Monoclonal antibody to the kinase prevents the stimulation, and monoclonal antibody to human DNA polymerase alpha neutralizes the enhanced activity. Reduced DNA polymerase alpha activity is obtained from noncycling HeLa cells and this activity has lower fidelity when copying synthetic primer-templates than that obtained from log phase cultures. After exposure to the kinase, the fidelities and activities of the polymerase from both sources increase by 2- to 3-fold. This improved accuracy is not accompanied by the appearance of triphosphatase or DNase activities. Exposure to the protein kinase reduces the Km for activated DNA and for poly(dA-dT) but not for dNTPs. Moreover, the Vmax for activated DNA but not for poly(dA-dT) is increased approximately 2- to 3-fold. These alterations suggest a role for protein phosphorylation in modulating DNA polymerase alpha.