Project description:Bacterial extracellular vesicles (EVs) are known to mediate intercellular communication, virulence, and immune modulation. Here we show that bacteria can utilise EVs also as recyclable nutrient reservoirs. Using Bacillus cereus as a model organism, we demonstrate that EVs exhibit distinct dynamics depending on growth conditions: EVs produced in complex nutrient-rich media undergo time-dependent degradation, while those produced in defined nutrient-limited conditions remain stable and accumulate. We observe similar EV degradation patterns in Staphylococcus aureus. Time-resolved multi-omics profiling reveals that EVs containing the lipid sphingomyelin undergo progressive degradation. Using pharmacological inhibition, knockout mutants, and enzymatic complementation, we show that this process is driven by secreted sphingomyelinase (SMase). This enzyme contributes to degradation of sphingomyelin-containing EVs, thereby releasing their biomolecular cargo which can be used as a nutrient source. Growth assays confirm that SMase-mediated EV degradation provides a growth advantage when nutrients become depleted, thus establishing EVs as dynamic nutrient reservoirs.
Project description:This study aimed to use pan-viral detection microarrays to identify viruses in serum from cases of acute pediatric febrile illness in a tropical setting. Patient clinical data and serum samples were collected between 2005 and 2009 as part of an ongoing pediatric dengue virus study at the Hospital Infantil Manuel de Jesús Rivera in Managua, Nicaragua. This study focused on patients who presented with dengue-like illness but who tested negative for dengue-virus infection. We hypothesized that non-dengue viruses or previously uncharacterized viruses might be causing these illnesses. The Virochip microarray is capable of detecting known viruses and discovering novel viruses. This series includes 153 arrays corresponding to 148 cases and 5 HeLa controls. Keywords: viral detection, tropical febrile illness, dengue virus, Nicaragua, Virochip
Project description:Different populations of the same species survive different environments through local adaptation. Temperature is one of the most important driving forces that could result in local adaptation. Here, we studied the influence of extreme low temperature on the survival of two genetically and geographically distinct populations of the free-living Caenorhabditis briggsae. We found that Caenorhabditis briggsae strains of temperate origin had a cold resistant phenotype, while those originating from a tropical climate had reduced survival after cold treatment. Using this phenotypic difference between geographically diverse populations as a model for how species adapt to their local environment, we then analyzed the transcriptional profiles of two Caenorhabditis briggsae strains of tropical and temperate origin to find genes that are involved in survival after extreme cold. In summary, the response to the extreme low temperature that clearly distinguishes the temperate and tropical Caenorhabditis briggsae strains could serve as an excellent example for studying local adaption of species that show genetic separation associated with their geographical distribution.
