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- Ramesh, Malavika, et al.
(författare)
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Age-dependent pleomorphism in Mycobacterium monacense cultures
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Annan publikation (populärvet., debatt m.m.)abstract
- Changes in cell shape and pleomorphism have been shown to be an integral part of the mycobacterial life cycle, however, systematic investigations into its patterns of pleomorphic behaviour in connection with stages or conditions of growth is scarce. We have studied the complete growth-cycle of Mycobacterium monacense cultures, a Non-Tuberculous Mycobacterium (NTM), in solid as well as liquid media. We provide data showing changes in cell shape from rod to coccoid and occurrence of refractive cells ranging from Phase Grey to phase Bright (PGB) in appearance upon ageing. Data further showed that changes in cell shape observed under the microscope could be correlated to the biphasic nature of the growth curves for M. monacense (as well as the NTM Mycobacterium boenickei) as measured by the absorbance of liquid cultures. Using the complete M. monacense genome we identified genes involved in cell morphology, and transcriptome analyses at different stages of growth revealed changes in their mRNA levels. One gene of interest, dnaK_3, that showed strong upregulation during stationary phase, was identified as an MreB-like homolog based on the protein domain architecture. Exogenous overexpression of M. monacense dnaK_3 in Mycobacterium marinum resulted in morphological changes with an impact on the frequency of occurrence of PGB cells. However, the introduction of an anti-sense "gene" targeting M. marinum dnaK_3 did not show such effects. Using dnaK_3-lacZ reporter constructs we provide data that these differences could be attributed to differences in the regulation of dnaK_3 in the two species. Together, this suggests that although its regulation may vary between mycobacterial species, dnaK_3 might be involved in the mechanism influencing mycobacterial cell shape.
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| 4. |
- Ramesh, Malavika, et al.
(författare)
-
Age-dependent pleomorphism in Mycobacterium monacense cultures
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Annan publikation (populärvet., debatt m.m.)abstract
- Changes in cell shape and pleomorphism have been shown to be an integral part of the mycobacterial life cycle, however, systematic investigations into its patterns of pleomorphic behaviour in connection with stages or conditions of growth is scarce. We have studied the complete growth-cycle of Mycobacterium monacense cultures, a Non-Tuberculous Mycobacterium (NTM), in solid as well as liquid media. We provide data showing changes in cell shape from rod to coccoid and occurrence of refractive cells ranging from Phase Grey to phase Bright (PGB) in appearance upon ageing. Data further showed that changes in cell shape observed under the microscope could be correlated to the biphasic nature of the growth curves for M. monacense (as well as the NTM Mycobacterium boenickei) as measured by the absorbance of liquid cultures. Using the complete M. monacense genome we identified genes involved in cell morphology, and transcriptome analyses at different stages of growth revealed changes in their mRNA levels. One gene of interest, dnaK_3, that showed strong upregulation during stationary phase, was identified as an MreB-like homolog based on the protein domain architecture. Exogenous overexpression of M. monacense dnaK_3 in Mycobacterium marinum resulted in morphological changes with an impact on the frequency of occurrence of PGB cells. However, the introduction of an anti-sense "gene" targeting M. marinum dnaK_3 did not show such effects. Using dnaK_3-lacZ reporter constructs we provide data that these differences could be attributed to differences in the regulation of dnaK_3 in the two species. Together, this suggests that although its regulation may vary between mycobacterial species, dnaK_3 might be involved in the mechanism influencing mycobacterial cell shape.
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- Ramesh, Malavika, et al.
(författare)
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Branching morphology in non-tuberculous mycobacteria Mycobacterium senegalense and Mycobacterium malmoense
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Annan publikation (populärvet., debatt m.m.)abstract
- Understanding mycobacterial growth cycle has been a challenging topic ever since the identification of Mycobacterium tuberculosis (Mtb) as the causal agent of Tuberculosis. Diverse metabolic pathways, changes in cell shape and/or size under various growth and environmental conditions, dormancy and virulence are some of the major factors that have made mycobacterial studies complex and challenging. Over the years, many mycobacterial species classified as Non-Tuberculous Mycobacteria (NTM) have been isolated from humans, animals and identified as pathogens. In this study, we have observed and described the cell morphology of two NTMs that showed branching/filamentous growth. Mycobacterium senegalense (Msen), causative agent of bovine farcy showed extensive branching with spore-like phase grey and phase bright (PGB) structures similar to the ones observed in a slow-growing NTM Mycobacterium malmoense (Mmal), known to cause TB-like lung infections in humans. Global transcriptome analyses of various genes is suggestive of pathways and regulations that may be responsible for the pleiomorphsim in general and specifically for branching in Msen and Mmal. One such gene that was analysed was the wag31, which has been shown to localise preferably at branch points.
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- Ramesh, Malavika, et al.
(författare)
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Branching morphology in the non-tuberculous mycobacteria Mycobacterium senegalense and Mycobacterium malmoense
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Annan publikation (populärvet., debatt m.m.)abstract
- Understanding mycobacterial growth cycle has been a challenging topic ever since the identification of Mycobacterium tuberculosis (Mtb) as the causal agent of Tuberculosis. Diverse metabolism, changes in cell shape and/or size under various growth and environmental conditions, dormancy and virulence are some of the major factors that has posed mycobacterial studies as very challenging. Over the years, many mycobacterial species classified as Non-Tuberculous Mycobacteria (NTM) have been isolated from humans, animals and identified as pathogens. In this study, we have observed and described the cell morphology of two NTMs that showed branching/filamentous growth. Mycobacterium senegalense (Msen), causative agent of bovine farcy showed extensive branching with spore-like phase grey and phase bright (PGB) structures similar to the ones observed in a slow-growing NTM Mycobacterium malmoense (Mmal), known to cause TB-like lung infections in humans. Global transcriptome analyses of various genes is suggestive of pathways and regulations that may be responsible for the pleiomorphsim in general and specifically for branching in Msen and Mmal. One such gene that was analysed was the wag31, which has been shown to localise preferably at branch points.
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