Biology subjects

Lima, J.

Publications and source records attributed to Lima, J..

3 recordsLinked to original sources

bioRxiv2018

Skin microbiome modulation induced by probiotic solutions

BackgroundThe skin is colonized by a large number of microorganisms, of which most are beneficial or harmless. However, disease states of skin have specific microbiome compositions that are different from those of healthy skin. Gut microbiome modulation through fecal transplant has proven as a valid therapeutic strategy in diseases such as Clostridium difficile infections. Therefore, techniques to modulate the skin microbiome composition may become an interesting therapeutic option in diseases affecting the skin such as psoriasis or acnes vulgaris.\n\nHere we have used mixtures of different skin microbiome components to alter the composition of a recipient skin microbiome.\n\nResultsWe show that after sequential applications of a donor microbiome, the recipient microbiome becomes similar to that of the donor. After intervention, an initial, week-long phase is characterized by dominance of donor strains. The level of engraftment depends on the composition of the recipient and donor microbiomes, and the applied bacterial load. We observed higher engraftment using a multi-strain donor solution with recipient skin rich in Cutibacterium acnes subtype H1 and Leifsonia.\n\nConclusionsWe have demonstrated the use of living bacteria to modulate skin microbiome composition.

microbiology↗

bioRxiv2018

HaploVectors: an integrative analytical tool for phylogeography

Sets of local populations show different degrees of gene flow due to dispersal barriers and environmental constraints, which renders genetic composition gradients among populations (genetic turnover). Unveiling biogeographic correlates of genetic turnover is paramount for phylogeography. While some processes (genetic drift, secondary contact) may erase the historical track of genetic turnover, vicariance or ancient dispersal likely leads to genetic divergence among populations. Yet available analyses do not permit direct inference about mechanisms driving genetic turnover. We propose a novel analytical approach called genvector analysis, which fulfills this gap by decomposing genetic compositional dissimilarities between populations based on either haplotypes or other genetic data into genetic eigenvectors. Such procedure allows exploring genetic turnover among sets of local populations, and analyzing their biogeographic correlates based on null model tests. We evaluate the statistical performance of the method on simulated datasets. We also analyzed biogeographic correlates of genetic turnover of Akodon cursor in the Brazilian Atlantic Forest. Results revealed that genvector analysis is robust to discriminate biogeographic drivers of genetic turnover. For Akodon cursor analysis, we observed that while for the entire species, all predictors considered (except for elevation) explained genetic turnover, within phylogroups some factors varied their importance. Genvector analysis was demonstrated to be useful for several different purposes in phylogeography, and complementary to classic analytical tools widely used by phylogeographers, such as AMOVA or DAPC. The role of ancient versus recent biogeographic events, the relationship between morphological divergence or abiotic variables and genetic turnover can easily be investigated using genvector analysis.

ecology↗

bioRxiv2017

Discriminative aversive learning and amygdala responsivity is enhanced in mice with reduced serotonin transporter activity

The serotonin (5-HT) transporter (5-HTT) regulates 5-HT availability at the synapse. Low or null 5-HTT expression results in increased 5-HT availability and has been reported to produce anxious and depressive phenotypes, although this remains highly controversial despite two decades of investigation. Paradoxically, SSRIs, which also increase 5-HT availability, reduce the symptoms of anxiety and depression. An emerging network plasticity theory of 5-HT function argues that, rather than influencing mood directly, increasing 5-HT availability enhances learning about emotionally-significant events but evidence supporting this theory is inconclusive. Here, we tested one key prediction of this theory: that increased 5-HT availability enhances aversive learning. In experiment 1, we trained 5-HTT knock-out mice (5-HTTKO), which have increased 5-HT availability, and wild-type mice (WT) on an aversive discrimination learning task in which one auditory cue was paired with an aversive outcome whereas a second auditory cue was not. Simultaneously we recorded neuronal and hemodynamic responses from the amygdala, a brain region necessary for aversive learning. 5-HTTKO mice exhibited superior discrimination learning than WTs, and had stronger theta-frequency neuronal oscillations and larger amygdala hemodynamic responses to the aversive cues, which predicted the extent of learning. In experiment 2, we found that acute SSRI treatment (in naive non-transgenic mice), given specifically before fear learning sessions, enhanced subsequent fear memory recall. Collectively, our data demonstrate that reducing 5-HTT activity (and thereby increasing 5-HT availability) enhances amygdala responsivity to aversive events and facilitates learning for emotionally-relevant cues. Our findings support the network plasticity theory of 5-HT function.

neuroscience↗