Nasal Priming with Lactobacillus rhamnosus CRL1505 Stimulates Mononuclear Phagocytes of Immunocompromised Malnourished Mice: Improvement of Respiratory Immune Response

The effect of Lactobacillus rhamnosus CRL1505 (Lr) on macrophages (Ma) and dendritic cells (DC) in the orchestration of anti-pneumococcal immunity was stud     

Rapid identification and interpretation of gene–environment associations using the new R.SamBada landscape genomics pipeline

sam βada is a genome–environment association software, designed to search for signatures of local adaptation. However, pre‐ and postprocessing of data can be labour‐intensive, preventing wider uptake of the method. We have now developed R.SamBada, an r ‐package providing a pipeline for landscape genomic analysis based on sam βada , spanning from the retrieval of environmental conditions at sampling locations to gene annotation using the Ensembl genome browser. As a result, R.SamBada standardizes the landscape genomics pipeline and eases the search for candidate genes of local adaptation, enhancing reproducibility of landscape genomic studies. The efficiency and power of the pipeline is illustrated using two examples: sheep populations from Morocco with no evident population structure and Lidia cattle from Spain displaying population substructuring. In both cases, R.SamBada enabled rapid identification and interpretation of candidate genes, which are further discussed in the light of local adaptation. The package is available in the r CRAN package repository and on GitHub (github.com/SolangeD/R.SamBada).     

Sub-chronic iron overload triggers oxidative stress development in rat brain: implications for cell protection

This work was aimed to test the hypothesis that sub-chronic administration of iron-dextran (Fe-dextran) (six doses of 50 mg Fe-dextran/kg) to rats triggers a transient oxidative stress in brain and mechanisms of cellular antioxidant defence. After 2 h of administration of the 6th dose, a significant increase of total Fe, the labile Fe pool (LIP), the lipid radical (LR^?)/α-tocopherol (α-T) content ratio were observed, as compared to values in control brain homogenates. The ascorbyl radical (A^?)/ascorbate (AH^?) content ratio and the oxidation rate of 2′,7′-dichlorodihidrofluorescein (DCFH-DA) were significantly higher in Fe-dextran treated rats, as compared to values in brain from control rats after 4 h treatment. An increase in both catalase (CAT) and superoxide dismutase (SOD) activity was observed at 8 and 1–2 h, respectively. No significant changes were detected in the nuclear factor-κB (NF-κB) levels in nuclear extracts from rat brains after 1–8 h of Fe-dextran administration. After 2 h of Fe administration Fe concentration in cortex, striatum and hippocampus was significantly increased as compared to the same areas from control animals. Both, CAT and SOD activities were significantly increased in cortex after Fe administration over control values, without changes in striatum and hippocampus. Taken as a whole, sub-chronic Fe administration enhances the steady state concentration of Fe in the brain LIP that favors the settlement of an initial oxidative stress condition, both at hydrophilic and lipophilic compartments, resulting in cellular protection evidenced by antioxidant enzyme upregulation.     

Leaf wax n‐alkane patterns of six tropical montane tree species show species‐specific environmental response

It remains poorly understood how the composition of leaf wax n‐alkanes reflects the local environment. This knowledge gap inhibits the interpretation of plant responses to the environment at the community level and, by extension, inhibits the applicability of n‐alkane patterns as a proxy for past environments. Here, we studied the n‐alkane patterns of five Miconia species and one Guarea species, in the Ecuadorian Andes (653–3,507 m a.s.l.). We tested for species‐specific responses in the average chain length (ACL), the C₃₁/(C₃₁ + C₂₉) ratio (ratio), and individual odd n‐alkane chain lengths across an altitudinally driven environmental gradient (mean annual temperature, mean annual relative air humidity, and mean annual precipitation). We found significant correlations between the environmental gradients and species‐specific ACL and ratio, but with varying magnitude and direction. We found that the n‐alkane patterns are species‐specific at the individual chain length level, which could explain the high variance in metrics like ACL and ratio. Although we find species‐specific sensitivity and responses in leaf n‐alkanes, we also find a general decrease in “shorter” (<C₂₉) and an increase in “longer” (>C₃₁) chain lengths with the environmental gradients, most strongly with temperature, suggesting n‐alkanes are useful for reconstructing past environments.     

Tuning of the FMN binding and oxido-reduction properties by neighboring side chains in Anabaena flavodoxin

Contribution of three regions (phosphate-binding, 50’s and 90’s loops) of Anabaena apoflavodoxin to FMN binding and reduction potential was studied. Thr12 and Glu16 did not influence FMN redox properties, but Thr12 played a role in FMN binding. Replacement of Trp57 with Glu, Lys or Arg moderately shifted E_ox/sq and E_sq/hq and altered the energetic of the FMN redox states binding profile. Our data indicate that the side chain of position 57 does not modulate E_ox/sq by aromatic stacking or solvent exclusion, but rather by influencing the relative strength of the H-bond between the N(5) of the flavin and the Asn58-Ile59 bond. A correlation was observed between the isoalloxazine increase in solvent accessibility and less negative E_sq/hq. Moreover, E_sq/hq became less negative as positively charged residues were added near to the isoalloxazine. Ile59 and Ile92 were simultaneously mutated to Ala or Glu. These mutations impaired FMN binding, while shifting E_sq/hq to less negative values and E_ox/sq to more negative. These effects are discussed on the bases of the X-ray structures of some of the Fld mutants, suggesting that in Anabaena Fld the structural control of both electron transfer steps is much more subtle than in other Flds.     

Gαo/i-stimulated proteosomal degradation of RGS20: A mechanism for temporal integration of Gs and Gi pathways

The G_s and G_i pathways interact to control the levels of intracellular cAMP. Although coincident signaling through G_s and G_i-coupled receptors can attenuate G_s-stimulated cAMP levels, it is not known if prior activation of the G_i pathway can affect signaling by G_s-coupled receptors. We have found that activated Gα_o/i interact with RGS20, a GTPase activating protein for members of the Gα_ο/i family. Interaction between Gα_o/i and RGS20 results in decreased cellular levels of RGS20. This decrease was induced by activated Gα_o and Gα_i2 but not by Gα_q, Gα_i1 or Gα_i3. The Gα_o/i-induced decrease in RGS20 can be blocked by proteasomal inhibitors lactacystin or MG132. Activated Gα_o stimulates the ubiquitination of RGS20. The serotonin-1A receptor that couples to G_o/i reduces the levels of RGS20 and this effect is blocked by lactacystin, suggesting that G_o/i promotes the degradation of RGS20. Expression of RGS20 attenuates the inhibition of β-adrenergic receptor-induced cAMP levels mediated by the serotonin-1A receptor. Prior activation of the serotonin-1A receptor results in loss of the RGS20-mediated attenuation, and the loss of attenuation is blocked when lactacystin is included during the prior treatment. These observations suggest that G_o/i-coupled receptors, by stimulating the degradation of RGS20, can regulate how subsequent activation of the G_s and G_i pathways controls cellular cAMP levels, thus allowing for signal integration.     

RAPD-PCR analysis of Staphylococcus aureus strains isolated from bovine and human hosts

Staphylococcus aureus is one of the most important pathogens in humans and animals. In this study eighty strains were analyzed by RAPD-PCR to assess the genetic relationship between S. aureus isolates from bovine and human hosts. Results were compared with those obtained by biotyping. Fifty-two percent of the S. aureus isolates belonged to a host specific biotype (human, bovine and poultry). Bovine and human ecovars were the most prevalent. Dendrogram obtained by RAPD results showed that all the isolates clustered into eleven groups (A-K) at a relative genetic similarity of less than 30% when analyzed with the three primers. Group A clustered 95% of the human host isolates and the remaining groups (B-K) clustered the bovine host isolates. Principal coordinate analysis also showed that the isolates could be arbitrarily divided into two groups, bovine and human, by the second coordinate. Only 9 isolates (11%) were not clustered into these groups. The genetic diversity among the S. aureus isolates from bovine hosts is relatively low compared to that of isolates from human hosts. There were no statistically significant differences among isolated from bovine and human hosts. This study shows that RAPD-PCR assayed with three primers can be successfully applied to assess the genetic relationship of S. aureus isolates from different hosts.