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Electron microscopic observations of intracytoplasmic membrane systems and cell division in Mycobacterium
1Electron Microscopic Laboratory, National Institute for Leprosy Research, Tokyo, Japan.
Abstract:
The fine structures and the interconnections between the intracytoplasmic membrane systems and cell division of murine leprosy bacilli in liver tissue from mice infected intraperitoneally with Mycobacterium lepraemurium, Hawaiian strain, were studied in ultrathin serial sections at the electron microscopic level. Intracellular membranous organelles (mesosomes) were seen as vesicular, tubular and/or lamellar structures. The formation of mesosomes appeared to be initiated by invagination and/or folding of the cytoplasmic membrane. A few dividing bacilli were observed. The lateral extension and the centripetal growth of the septal wall seemed to result from the original development of cytoplasmic membrane occurring at or near the leading edge of the nascent septum. After the septum formation was completely accomplished, the separation of two new daughter cells is assumed to occur. The mesosome was associated with the newly formed cytoplasmic membrane (septal wall). It was shown that both the cytoplasmic membrane and the mesosome played an important part in septum formation.
Insights
Electron microscopy revealed that mesosomes and cytoplasmic membranes are crucial for Mycobacterium lepraemurium cell division. These structures facilitate septum formation, leading to the separation of new daughter cells in infected mouse liver tissue.
Area of Science:
- Microbiology
- Cell Biology
- Electron Microscopy
Background:
- Mycobacterium lepraemurium causes murine leprosy.
- Understanding bacterial cell division is key to developing new treatments.
- Intracytoplasmic membrane systems play roles in bacterial growth.
Purpose of the Study:
- To investigate the role of intracytoplasmic membrane systems in Mycobacterium lepraemurium cell division.
- To elucidate the fine structure and function of mesosomes during cell division.
Main Methods:
- Ultrathin serial sections of infected mouse liver tissue.
- Electron microscopy analysis of Mycobacterium lepraemurium.
- Observation of intracellular membranous organelles (mesosomes) and cell division.
Main Results:
- Mesosomes observed as vesicular, tubular, and lamellar structures.
- Mesosome formation initiated by cytoplasmic membrane invagination/folding.
- Cytoplasmic membrane and mesosomes are integral to septum formation and cell separation.
Conclusions:
- Both cytoplasmic membrane and mesosomes are essential for Mycobacterium lepraemurium septum formation.
- Mesosomes associate with the newly formed cytoplasmic membrane during division.