Project description:In Staphylococcus aureus, the role of the GGDEF domain containing protein GdpS remains poorly understood. Previous studies reported that gdpS mutant strains had decreased biofilm formation due to changes in icaADBC expression that were independent of cyclic-di-GMP levels. We deleted gdpS in three unrelated S. aureus isolates, and analyzed the resultant mutants for alterations in biofilm formation, metabolism and transcription. Dynamic imaging during biofilm development showed that GdpS inhibited early biofilm formation in only two out of the three strains examined, without affecting bacterial survival. However, quantification of biofilm formation using crystal violet staining revealed that inactivation of gdpS affected biofilm formation in all three studied strains. Extraction of metabolites from S. aureus cells confirmed the absence of cyclic-di-GMP, suggesting that biofilm formation in this species differs from that in other Gram-positive organisms. In addition, targeted mutagenesis demonstrated that the GGDEF domain was not required for GdpS activity. Transcriptomic analysis revealed that the vast majority of GGDEF-regulated genes were involved in virulence, metabolism, cell wall biogenesis and eDNA release. Finally, expression of lrgAB or deletion of cidABC in a strain lacking gdpS confirmed the role of GdpS on regulation of eDNA production that occurred without an increase in cell autolysis. In summary, S. aureus GdpS contributes to cell-to-cell interactions during early biofilm formation by influencing expression of lrgAB and cidABC mediated eDNA release. We conclude that GdpS acts as a negative regulator of eDNA release.
Project description:Monitoring microbial communities can aid in understanding the state of these habitats. Environmental DNA (eDNA) techniques provide efficient and comprehensive monitoring by capturing broader diversity. Besides structural profiling, eDNA methods allow the study of functional profiles, encompassing the genes within the microbial community. In this study, three methodologies were compared for functional profiling of microbial communities in estuarine and coastal sites in the Bay of Biscay. The methodologies included inference from 16S metabarcoding data using Tax4Fun, GeoChip microarrays, and shotgun metagenomics.
Project description:In Staphylococcus aureus, the role of the GGDEF domain containing protein GdpS remains poorly understood. Previous studies reported that gdpS mutant strains had decreased biofilm formation due to changes in icaADBC expression that were independent of cyclic-di-GMP levels. We deleted gdpS in three unrelated S. aureus isolates, and analyzed the resultant mutants for alterations in biofilm formation, metabolism and transcription. Dynamic imaging during biofilm development showed that GdpS inhibited early biofilm formation in only two out of the three strains examined, without affecting bacterial survival. However, quantification of biofilm formation using crystal violet staining revealed that inactivation of gdpS affected biofilm formation in all three studied strains. Extraction of metabolites from S. aureus cells confirmed the absence of cyclic-di-GMP, suggesting that biofilm formation in this species differs from that in other Gram-positive organisms. In addition, targeted mutagenesis demonstrated that the GGDEF domain was not required for GdpS activity. Transcriptomic analysis revealed that the vast majority of GGDEF-regulated genes were involved in virulence, metabolism, cell wall biogenesis and eDNA release. Finally, expression of lrgAB or deletion of cidABC in a strain lacking gdpS confirmed the role of GdpS on regulation of eDNA production that occurred without an increase in cell autolysis. In summary, S. aureus GdpS contributes to cell-to-cell interactions during early biofilm formation by influencing expression of lrgAB and cidABC mediated eDNA release. We conclude that GdpS acts as a negative regulator of eDNA release. Three strains UAMS-1, SA113 and SA564 were used in this study to compare wt with gdpS mutant after 5 hours of growth in static conditions (biofilm formation).
Project description:Lake trout (Salvelinus namaycush) are a top-predator species in the Laurentian Great Lakes that are often used as bioindicators of chemical stressors in the ecosystem. Although many studies are done using these fish to determine concentrations of stressors like legacy persistent, bioaccumulative and toxic chemicals, there are currently no proteomic studies on the biological effects these stressors have on the ecosystem. This lack of proteomic studies on Great Lakes lake trout is because there is currently no complete, comprehensive protein database for this species. In this research, we aimed to use proteomic methods and established protein databases from NCBI and UniProtKB to identify potential proteins in the lake trout species. The current study utilized heart tissue and blood from two separate lake trout. Our previous published work on the lake trout liver revealed 4,194 potential protein hits in the NCBI databases and 3,811 potential protein hits in the UniProtKB databases. In the current study, using the NCBI databases we identified 838 potential protein hits for the heart and 580 potential protein hits for the blood of the first lake trout (biological replicate 1). In the second lake trout (biological replicate 2), using the NCBI databases we identified 1,180 potential protein hits for the heart and 561 potential protein hits for the blood. Similar results were obtained using the UniProtKB databases. This study builds on our previous work by continuing to build the first comprehensive lake trout protein database. Through this investigation, we are also able to make observations as to protein homology through evolutionary relationships.
Project description:Lake trout are used as bioindicators for toxics exposure in the Great Lakes ecosystem. However, there is no knowledge about lake trout proteome. Here we performed the first lake trout (Salvelinus namaycush) liver proteomics and searched the databases against (NCBI and UniProtKB) Salvelinus, Salmonidae, Actinopterygii and the more distant Danio rerio. In the NCBI search, we identified 4371 proteins in 1252 clusters. From these proteins, we found 2175 proteins in Actinopterygii 1253 in Salmonidae, 69 in Salvelinus and 901 in Danio rerio NCBI searches. In the UniProtKB search, we identified 2630 proteins in 1100 clusters. From these proteins, we found 317 in Actinopterygii, 1653 in Salmonidae, 37 in Salvelinus and 666 in Danio rerio UniProtKB searches. A similar outcome was also obtained from a technical replicate experiment. A large number of lake trout liver proteins were not in any Salvelinus databases, suggesting that lake trout liver proteins have homologues to some proteins from the Salmonidae family and Actinopterygii class, as well as to the species Danio rerio, a more highly studied Cypriniformes fish. Therefore, our study not only builds the first comprehensive lake trout protein database, but also establishes protein homology-based evolutionary relationships between the fish within their family and class, as well as distant-related fish (lake trout and zebrafish). In addition, this study opens the possibility of identifying evolutionary relationships (i.e. adaptive mutations) between various groups (i.e. zebrafish, Salmonidae, Salvelinus and lake trout) through evolutionary proteomics
Project description:Deep Lake is a hypersaline system in Antarctica (68°33’36.8S, 78°11’48.7E) that is so saline it remains liquid at –20°C (DeMaere et al 2013). The lake is dominated by haloarchaea, comprising a low-complexity community that differs greatly to warm-hot latitude hypersaline systems, is hierarchical structured, and supports a high level of intergenera gene exchange. Metaproteomics was performed on biomass that was collected in the austral summer of 2008 by sequential size fractionation (20 – 3 µm, 3 – 0.8 µm, 0.8 – 0.1 µm). The data were integrated to obtain a systems level view of the active host-virus interactions occurring in this novel aquatic Antarctic system. DeMaere MZ, Williams TJ, Allen MA, Brown MV, Gibson JA, Rich J, Lauro FM, Dyall-Smith M, Davenport KW, Woyke T, Kyrpides NC, Tringe SG, Cavicchioli R (2013) High level of intergenera gene exchange shapes the evolution of haloarchaea in an isolated Antarctic lake. Proc Natl Acad Sci USA 110: 16939-16944