Biology subjects

de la Torre, M.

Publications and source records attributed to de la Torre, M..

3 recordsLinked to original sources

bioRxiv2021

High-throughput imaging of Caenorhabditis elegans aging using collective activity monitoring

The genetic manipulability and short lifespan of C. elegans make it an important model for aging research. Widely applied methods for measurements of worm aging based on manual observation are labor intensive and low-throughput. Here, we describe the Worm Collective Activity Monitoring Platform (WormCamp), a system for assaying aging in C. elegans by monitoring activity of populations of worms in standard 24-well plates. We show that metrics based on the rate of decline in collective activity can be used to estimate the average lifespan and locomotor healthspan in the population. Using the WormCamp, we assay a panel of highly divergent natural isolates of C. elegans and show that both lifespan and locomotor healthspan display substantial heritability. To facilitate analysis of large numbers of worms, we developed a robotic imaging system capable of simultaneous automated monitoring of activity, lifespan, and locomotor healthspan in up to 2,304 populations containing a total of ~90,000 animals. We applied the automated system to conduct a large-scale RNA interference screen for genes that affect lifespan and locomotor healthspan. The WormCamp system is complementary to other current automated methods for assessing C. elegans aging and is well suited for efficiently screening large numbers of conditions.

bioengineering↗

bioRxiv2021

The quorum sensing system NprR-NprRB contributes to spreading and fitness in colony biofilms of Bacillus thuringiensis.

Quorum sensing (QS) are intercellular communication mechanisms to coordinate bacterial gene expression in response to signaling molecules. In Bacillus thuringiensis the QS system NprR-NprRB (receptor protein-signaling peptide) regulates the expression of genes related to nutrient scavenging during necrotrophism and also modulates sporulation onset. However, the relevance of QS in free-living stages of B. thuringiensis is less known. In this work, we depict the contribution of this QS system to spreading in colony biofilms. Through a spreading assay in spotted colonies of B. thuringiensis Bt8741 Wt and derived mutants, we find that the spreading phenotype depends on the NprR regulator and on the extracellular signaling NprRB peptide. We also show that this phenotype is associated to an increased fitness of the bacterium in these experimental conditions. Exogenous addition of a lipopeptide surfactant was sufficient to recover spreading in the {Delta}nprR-nprRB mutant, indicating that the phenotype could be mediated by the lipopeptide kurstakin. Finally, we suggest that the spreading is relevant in nature, since it occurs in the sole presence of soil nutrients, and it is conserved in several species of Bacillus commonly found in soil. This novel function of NprR-NprRB highlights the relevance of this QS system on the evolution and on the free-lifestyle ecology of B. thuringiensis.

microbiology↗

bioRxiv2019

Rap-protein paralogs of B. thuringiensis: a multifunctional and redundant regulatory repertoire for the control of collective functions.

Quorum Sensing (QS) are mechanisms of synthesis and detection of signaling molecules to regulate gene expression and coordinate behaviors in bacterial populations. In Bacillus subtilis (Bs), multiple paralog Rap-Phr QS systems (receptor-signaling peptide) are highly redundant and multifunctional, interconnecting the regulation of differentiation processes such as sporulation and competence. However, their functions in the B. cereus group are largely unknown. We evaluated the diversification of Rap-Phr systems in the B. cereus group as well as their functions, using Bacillus thuringiensis Bt8741 as model. Bt8741 codes for eight Rap-Phr systems; these were overexpressed to study their participation in sporulation, biofilm formation, extracellular proteolytic activity and spreading. Our results show that five Rap-Phr systems (RapC, K, F, I and RapLike) inhibit sporulation, two of which (RapK and RapF) probably dephosphorylate of Spo0F from the Spo0A phosphorelay; these two Rap proteins also inhibit biofilm formation. Five systems (RapC, F, F2, I1 and RapLike) decrease extracellular proteolytic activity; finally, four systems (RapC, F1, F2 and RapLike) participate in spreading inhibition. Our bioinformatic analyses showed that Rap proteins from the B. cereus group diversified into five pherogroups, and we foresee that functions performed by Rap proteins of Bt8741 could also be carried out by Rap homologs in other species within the group. These results indicate that Rap-Phr systems constitute a highly multifunctional and redundant regulatory repertoire that enables bacteria from the B. cereus group to efficiently regulate collective functions during the bacterial life cycle, in the face of changing environments.\n\nImportanceThe Bacillus cereus group of bacteria includes species of high economic, clinical, biological warfare and biotechnological interest, e.g. B. anthracis in bioterrorism, B. cereus in food intoxications and B. thuringiensis in biocontrol. Knowledge on the ecology of these bacteria is hindered due to our limited understanding about the regulatory circuits that control differentiation and specialization processes. Here, we uncover the participation of eight Rap quorum-sensing receptors in collective functions of B. thuringiensis. These proteins are highly multifunctional and redundant in their functions, linking ecologically relevant processes such as sporulation, biofilm formation, extracellular proteolytic activity, spreading, and probably other additional functions in species from the B. cereus group.

microbiology↗