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.     

Endocytosis in Trypanosoma cruzi (Euglenozoa: Kinetoplastea) epimastigotes: Visualization of ingested transferrin-gold nanoparticle complexes by confocal laser microscopy

Here we describe the visualization by confocal microscopy of ingested gold (15nm)-labeled transferrin in epimastigote forms of the protozoan Trypanosoma cruzi. Intracellular gold labeling was evident at two sites, which represent the bottom of the cytopharynx and the reservosomes. The gold tracer was best observed by confocal microscopy by using the 633nm excitation wavelength. Intracellular gold clusters larger than 60nm could be visualized by either gold reflection (light scattering) or photoluminescence modes. The gold reflection mode, the gold photoluminescence mode and the anti-transferrin immunofluorescence image of gold-labeled transferrin showed co-localization, thus demonstrating that the gold visualization modes did not represent artifacts or mislocalization of the biomarker. Visualization of protein-gold nanoparticle complexes by confocal microscopy thus emerges as a promising imaging tool to explore the endocytic pathway in trypanosomes and other cell types, as well as to perform immunolocalization studies using gold-labeled secondary antibodies.     

Presence of α-amylase inhibitor in some members of the subtribe Phaseolinae (Phaseoleae: Fabaceae)

The presence of α-amylase inhibitor (αAI), phytohemagglutinin (PHA), and phaseolin was determined by immunochemical and biochemical methods in different members of the subtribe Phaseolinae (Phaseoleae: Fabaceae). Active αAI was present in taxa from the Phaseolus vulgaris–P. coccineus complex (P. vulgaris, P. coccineus, and P. polyanthus), as well as in P. acutifolius in accordance with previous molecular data separating these groups of species from others in the genus. All other Phaseolus species tested lacked α-amylase inhibitory activity, although some of them had immunoreactive polypeptides. αAI was found to be a polymorphic trait among wild and cultivated accessions of P. vulgaris, P. coccineus, and P. acutifolius. The presence of αAI is not exclusive of the genus Phaseolus as one of the Vigna species sampled, V. linearis, also contained α-amylase inhibitory activity.     

De la valeur du barrage sexuel,comme critérium dans l'analyse d'une sporée tétrapolaire de basidiomycète: Pleurotus ostreatus

Sans résumé     

Molecular characterization of H2O2-forming NADH oxidases from Archaeoglobus fulgidus.

Three NADH oxidase encoding genes noxA-1, noxB-1 and noxC were cloned from the genome of Archaeoglobus fulgidus, expressed in Escherichia coli, and the gene products were purified and characterized. Expression of noxA-1 and noxB-1 resulted in active gene products of the expected size. The noxC gene was expressed as well but the protein produced showed no activity in the standard Nox assay. NoxA-1 and NoxB-1 are both FAD-containing enzymes with subunit molecular masses of 48 and 69 kDa, respectively. NoxA-1 exists predominantly as homodimer, NoxB-1 as monomer. NoxA-1 and NoxB-1 showed pH optimum of 8.0 and 6.5, with specific NADH oxidase activities of 5.8 U.mg-1 and 4.1 U.mg-1, respectively. Both enzymes were specific for NADH as electron donor, but with different apparent Km values (NoxA-1, 0.13 mm; NoxB-1, 0.011 mm). The apparent Km values for oxygen differed significantly (NoxA-1, 0.06 mm; NoxB-1, 2.9 mm). In contrast with all mesophilic homologues, both enzymes were found to produce predominantly H2O2 instead of H2O. Despite apparent similarities, NoxB-1 is essentially different from NoxA-1. Whereas NoxA-1 resembles typical H2O-producing Nox enzymes that are expected to have a role in oxidative stress defence, NoxB-1 belongs to a small group of enzymes that is involved in catalysing the reduction of unsaturated acids and aldehydes, suggesting a role in fatty acid oxidation. Moreover, NoxB-1 contains a ferredoxin-like motif, which is absent in NoxA-1.     

Co-fermentation of xylose and cellobiose by an engineered Saccharomyces cerevisiae

We have integrated and coordinately expressed in Saccharomyces cerevisiae a xylose isomerase and cellobiose phosphorylase from Ruminococcus flavefaciens that enables fermentation of glucose, xylose, and cellobiose under completely anaerobic conditions. The native xylose isomerase was active in cell-free extracts from yeast transformants containing a single integrated copy of the gene. We improved the activity of the enzyme and its affinity for xylose by modifications to the 5′-end of the gene, site-directed mutagenesis, and codon optimization. The improved enzyme, designated RfCO*, demonstrated a 4.8-fold increase in activity compared to the native xylose isomerase, with a K_m for xylose of 66.7?mM and a specific activity of 1.41?μmol/min/mg. In comparison, the native xylose isomerase was found to have a K_m for xylose of 117.1?mM and a specific activity of 0.29?μmol/min/mg. The coordinate over-expression of RfCO* along with cellobiose phosphorylase, cellobiose transporters, the endogenous genes GAL2 and XKS1, and disruption of the native PHO13 and GRE3 genes allowed the fermentation of glucose, xylose, and cellobiose under completely anaerobic conditions. Interestingly, this strain was unable to utilize xylose or cellobiose as a sole carbon source for growth under anaerobic conditions, thus minimizing yield loss to biomass formation and maximizing ethanol yield during their fermentation.