Articles by Jeremy J. Daniel in JoVE
Live Cell Fluorescence Microscopy to Observe Essential Processes During Microbial Cell Growth Matthew Howell1, Jeremy J. Daniel1, Pamela J.B. Brown1 1Division of Biological Sciences, University of Missouri Understanding the function of essential processes in bacteria is challenging. Fluorescence microscopy with target-specific dyes can provide key insights into microbial cell growth and cell cycle progression. Here, Agrobacterium tumefaciens is used as a model bacterium to highlight methods for live cell imaging for characterization of essential processes.
Other articles by Jeremy J. Daniel on PubMed
Draft Genome Sequence of Prosthecomicrobium Hirschii ATCC 27832T Genome Announcements. | Pubmed ID: 26586892 We report the draft genome sequence of Prosthecomicrobium hirschii ATCC 27832(T), an alphaproteobacterium with remarkable cellular morphologies. The chromosome comprises 6,484,983 bp in six scaffolds with a G+C content of 69%, and 6,066 potential coding sequences.
Short-Stalked Prosthecomicrobium Hirschii Cells Have a Caulobacter-Like Cell Cycle Journal of Bacteriology. | Pubmed ID: 26833409 The dimorphic alphaproteobacterium Prosthecomicrobium hirschii has both short-stalked and long-stalked morphotypes. Notably, these morphologies do not arise from transitions in a cell cycle. Instead, the maternal cell morphology is typically reproduced in daughter cells, which results in microcolonies of a single cell type. In this work, we further characterized the short-stalked cells and found that these cells have a Caulobacter-like life cycle in which cell division leads to the generation of two morphologically distinct daughter cells. Using a microfluidic device and total internal reflection fluorescence (TIRF) microscopy, we observed that motile short-stalked cells attach to a surface by means of a polar adhesin. Cells attached at their poles elongate and ultimately release motile daughter cells. Robust biofilm growth occurs in the microfluidic device, enabling the collection of synchronous motile cells and downstream analysis of cell growth and attachment. Analysis of a draft P. hirschii genome sequence indicates the presence of CtrA-dependent cell cycle regulation. This characterization of P. hirschii will enable future studies on the mechanisms underlying complex morphologies and polymorphic cell cycles.
Mini-Tn7 Insertion in an Artificial AttTn7 Site Enables Depletion of the Essential Master Regulator CtrA in the Phytopathogen Agrobacterium Tumefaciens Applied and Environmental Microbiology. | Pubmed ID: 27287320 Mechanistic studies of many processes in Agrobacterium tumefaciens have been hampered by a lack of genetic tools for characterization of essential genes. In this study, we used a Tn7-based method for inducible control of transcription from an engineered site on the chromosome. We demonstrate that this method enables tighter control of inducible promoters than plasmid-based systems and can be used for depletion studies. The method enables the construction of depletion strains to characterize the roles of essential genes in A. tumefaciens Here, we used the strategy to deplete the alphaproteobacterial master regulator CtrA and found that depletion of this essential gene results in dramatic rounding of cells, which become nonviable.