Biology subjects

Montero, N.

Publications and source records attributed to Montero, N..

3 recordsLinked to original sources

bioRxiv2018

How will changes in local climate affect hawksbill hatchling production in Brazil?

Local climatic conditions can influence sea turtle embryonic development and hatchling viability. Therefore, it is crucial to understand these influences as well as potential ramifications to population stability under future climate change. Here, we examined the influences of five climatic variables (air temperature, accumulated and average precipitation, humidity, solar radiation, and wind speed) at different temporal scales on hawksbill sea turtle (Eretmochelys imbricata) hatchling production at ten nesting beaches within two regions of Brazil (five nesting beaches in Rio Grande do Norte and five in Bahia). Air temperature and accumulated precipitation were the main climatic drivers of hawksbill hatching success across Brazil and in Rio Grande do Norte, while air temperature and average precipitation were the main climatic drivers of hatching success at Bahia. Solar radiation was the main climatic driver of emergence rate at both regions. Conservative and extreme climate scenarios show air temperatures are projected to increase, while precipitation projections vary between scenarios and regions throughout the 21st century. We predicted hatching success of undisturbed nests (no recorded depredation or storm-related impacts) will decrease in Brazil by 2100. This study shows the determining effects of different climate variables and their combinations on an important and critically endangered marine species.

zoology↗

bioRxiv2018

Enterococcus faecalis V583 LuxS/AI-2 system is devoid of role in intra-species quorum-sensing but contributes to virulence in a Drosophila host model

The AI-2 i nterspecies quorum-sensing molecule is produced by the LuxS enzyme and has been ascribed a role in virulence in several bacteria. The nosocomial pathogen Enterococcus faecalis inhabits several different environments where multispecies communities are established. However, despite the presence of a luxS gene in this pathogen, its role in E. faecalis pathogenesis has never been assessed. In the present work, we deleted the luxS gene from the vancomycin-resistant clinical isolate E. faecalis V583 and demonstrated the lack of AI-2 production by the mutant strain. Using microarrays and externally added (S)-4,5-dihydroxy-2,3-pentanedione we showed that AI-2 is not sensed by E. faecalis as a canonical quorum-sensing molecule and that the luxS mutation caused pleiotropic effects in gene expression, which could not be complemented by extracellularly added AI-2. These global differences in gene expression affected several gene functional roles, mainly those enrolled in metabolism and transport. Metabolic phenotypi ng of the luxS mutant, using Biolog plates, showed differences in utilization of galactose. AI-2 production by LuxS was shown to be irrelevant for some phenotypes related to the pathogenic potential of E. faecalis namely biofilm formation, adhesion to Caco-2 cells, resistance to oxidative stress and survival inside J-774 macrophages. However, the luxS mutant was attenuated when tested in the Drosophila septic injury model, as its deletion led to delayed fly death. Overall our findings show that differential gene expression related to the luxS mutation cannot be ascribed to quorum-sensing. Moreover, the role of LuxS appears to be limited to metabolism.

microbiology↗

bioRxiv2017

H2S mediates interbacterial communication through the air reverting intrinsic antibiotic resistance

Hydrogen sulfide, a gas classically considered as a by-product of cellular metabolism, is today recognized as a crucial gasotransmitter in Eukaryotes. Moreover, most bacteria harbor the eukaryotic orthologous genes for H2S synthesis, and these genes have been linked to different metabolic pathways.\n\nSome bacteria, however, produce high amounts of H2S in their extracellular space, a characteristic classically used for identification purposes. This is the case of Salmonella Typhimurium, which produces H2S by its phsABC operon. Here we show that extracellular release of H2S by S. Typhimurium is solely dependent on its phsABC operon. Furthermore, we show that S. Typhimurium and other H2S-producing bacteria can interact with physically distant bacteria through H2S production. We demonstrate how H2S can revert intrinsic cephalosporin resistance of Enterococccus faecalis and Enterococcus faecium to complete susceptibility. This study constitutes a significant step in the study of bacterial interplay and niche competition. Furthermore, as H2S releasing drugs have already been designed, our results open the way to future therapeutic alternatives for the treatment of infections caused by enterococci, multiresistant pathogens for which no treatments are clinically available.\n\nAuthor SummaryIt has been known for decades that bacteria can communicate with each other through the diffusion of metabolites in the media. However, the capacity of a bacterium to interact with other physically distant cell is a recent discovery of the 21st century. In this work we show how some well-studied bacteria, as it is Salmonella spp., interacts with other bacteria thanks to the compound hydrogen sulfide (H2S) that they produce and release to the environment.\n\nIn our study we have designed novel techniques that allow us to study the interaction between two bacteria, and we have seen that Salmonella is able to affect other species that is even 1 cm away, i.e., a distance corresponding to 10.0000 times its own size.\n\nWhat is more astonishing is that Enterococcus, when exposed to the H2S, is dramatically becomes susceptible to many antibiotics, to which it is supposed to be naturally resistant. Enterococcus spp. are responsible for life-threatening infections in hospitals worldwide. Thus, our observations reveal that bacteria can communicate through the air with H2S, and that this molecule can make bacteria that are highly resistant to antibiotics susceptible to antibiotics, making untreatable infections treatable with current antibiotics.

microbiology↗