Adaptations in humans for assessing physical strength from the voice

Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men''s physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.     

The role of CXCR2 activity in the contact hypersensitivity response in mice

The recruitment of polymorphonuclear neutrophil leukocytes (PMN) into a challenge site, and their subsequent activation, are thought to play a role in the elicitation of the contact hypersensitivity (CHS) response. The present study investigated the role played by CXCR2 activity in tissue PMN infiltration and subsequent triggering of CHS. Our results show that the cutaneous infiltration by PMN, induced by hapten challenge was dramatically inhibited in sensitized, CXCR2-deficient (CXCR2(-/-)) mice. Inhibition of PMN recruitment into the hapten-challenged ears of CXCR2(-/-) mice was associated with a consistent reduction of the CHS response (ear swelling) in CXCR2(-/-) mice as compared with that observed in neutropenic, wild-type (CXCR2(+/+)) mice. Prevention of skin PMN infiltration and the ear swelling response by the absence of functional CXCR2 was observed regardless of the hapten used. These data clearly suggest that CXCR2 activity plays an essential role in mediating cutaneous recruitment and activation of PMN, and thus indirectly regulates recruitment of hapten-primed T cells into challenge sites, with the subsequent elicitation of the CHS response. The role played by CXCR2 activity in the CHS response provides the rationale for testing CXCR2 inhibitors as a new therapeutic approach to skin diseases.     

Survival of gfp-tagged antagonistic bacteria in the rhizosphere of tomato plants and their effects on the indigenous bacterial community

The survival and colonization patterns of Pseudomonas putida PRD16 and Enterobacter cowanii PRF116 in the rhizosphere of greenhouse-grown tomato plants and the effects of their inoculation on the indigenous bacterial community were followed by selective plating, molecular fingerprinting, and confocal laser scanning microscopy (CLSM) over 3 weeks. Both strains, which showed in vitro antagonistic activity against Ralstonia solanacearum, were previously tagged with gfp. Seed and root inoculation were compared. Although plate counts decreased for both gfp-tagged antagonists, PRD16 showed a better survival in the rhizosphere of tomato roots independent of the inoculation method. Analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and CLSM confirmed the decrease in the relative abundance of the inoculant strains. Pronounced differences in the Pseudomonas community patterns for plants inoculated with PRD16 compared to the control were detected 3 weeks after root inoculation, indicating a longer-lasting effect. Analysis by CLSM showed rather heterogeneous colonization patterns for both inoculant strains. In comparison with seed inoculation, root inoculation led to a much better colonization as evidenced by all three methods. The colonization patterns observed by CLSM provide important information on the sampling strategy required for monitoring inoculant strains in the rhizosphere.     

The expression of nifB gene from Herbaspirillum seropedicae is dependent upon the NifA and RpoN proteins

The putative nifB promoter region of Herbaspirillum seropedicae contained two sequences homologous to NifA-binding site and a -24/-12 type promoter. A nifB::lacZ fusion was assayed in the backgrounds of both Escherichia coli and H. seropedicae. In E. coli, the expression of nifB::lacZ occurred only in the presence of functional rpoN and Klebsiella pneumoniae nifA genes. In addition, the integration host factor (IHF) stimulated the expression of the nifB::lacZ fusion in this background. In H. seropedicae, nifB expression occurred only in the absence of ammonium and under low levels of oxygen, and it was shown to be strictly dependent on NifA. DNA band shift experiments showed that purified K. pneumoniae RpoN and E. coli IHF proteins were capable of binding to the nifB promoter region, and in vivo dimethylsulfate footprinting showed that NifA binds to both NifA-binding sites. These results strongly suggest that the expression of the nifB promoter of H. seropedicae is dependent on the NifA and RpoN proteins and that the IHF protein stimulates NifA activation of nifB promoter.     

A model of DENV-3 infection that recapitulates severe disease and highlights the importance of IFN-γ in host resistance to infection

There are few animal models of dengue infection, especially in immunocompetent mice. Here, we describe alterations found in adult immunocompetent mice inoculated with an adapted Dengue virus (DENV-3) strain. Infection of mice with the adapted DENV-3 caused inoculum-dependent lethality that was preceded by several hematological and biochemical changes and increased virus dissemination, features consistent with severe disease manifestation in humans. IFN-γ expression increased after DENV-3 infection of WT mice and this was preceded by increase in expression of IL-12 and IL-18. In DENV-3-inoculated IFN-γ(-/-) mice, there was enhanced lethality, which was preceded by severe disease manifestation and virus replication. Lack of IFN-γ production was associated with diminished NO-synthase 2 (NOS2) expression and higher susceptibility of NOS2(-/-) mice to DENV-3 infection. Therefore, mechanisms of protection to DENV-3 infection rely on IFN-γ-NOS2-NO-dependent control of viral replication and of disease severity, a pathway showed to be relevant for resistance to DENV infection in other experimental and clinical settings. Thus, the model of DENV-3 infection in immunocompetent mice described here represents a significant advance in animal models of severe dengue disease and may provide an important tool to the elucidation of immunopathogenesis of disease and of protective mechanisms associated with infection.     

Alcohol Affects the Brain's Resting-State Network in Social Drinkers

Acute alcohol intake is known to enhance inhibition through facilitation of GABA_A receptors, which are present in 40% of the synapses all over the brain. Evidence suggests that enhanced GABAergic transmission leads to increased large-scale brain connectivity. Our hypothesis is that acute alcohol intake would increase the functional connectivity of the human brain resting-state network (RSN). To test our hypothesis, electroencephalographic (EEG) measurements were recorded from healthy social drinkers at rest, during eyes-open and eyes-closed sessions, after administering to them an alcoholic beverage or placebo respectively. Salivary alcohol and cortisol served to measure the inebriation and stress levels. By calculating Magnitude Square Coherence (MSC) on standardized Low Resolution Electromagnetic Tomography (sLORETA) solutions, we formed cortical networks over several frequency bands, which were then analyzed in the context of functional connectivity and graph theory. MSC was increased (p<0.05, corrected with False Discovery Rate, FDR corrected) in alpha, beta (eyes-open) and theta bands (eyes-closed) following acute alcohol intake. Graph parameters were accordingly altered in these bands quantifying the effect of alcohol on the structure of brain networks; global efficiency and density were higher and path length was lower during alcohol (vs. placebo, p<0.05). Salivary alcohol concentration was positively correlated with the density of the network in beta band. The degree of specific nodes was elevated following alcohol (vs. placebo). Our findings support the hypothesis that short-term inebriation considerably increases large-scale connectivity in the RSN. The increased baseline functional connectivity can -at least partially- be attributed to the alcohol-induced disruption of the delicate balance between inhibitory and excitatory neurotransmission in favor of inhibitory influences. Thus, it is suggested that short-term inebriation is associated, as expected, to increased GABA transmission and functional connectivity, while long-term alcohol consumption may be linked to exactly the opposite effect.