What are Mesosomes?

• Mesosomes and chondrioids are foldable into invaginations of the plasma membranes of bacteria. They are made through chemical fixation techniques that are used to prepare samples for electron microscopy.
• While a variety of functions were suggested for these structures during the 1960s, they were regarded as artifacts in the late 1970s, and they are not considered an integral part of the cell structure of bacteria cells. The extensions come in shape of vesicles tubules , and lamellae.
• Mesosomes typically are located in conjunction with the nuclear region or in close proximity to the cell division site.
• They are absent from the eukaryotes.
• The lamellae are made by flat vesicles when they are placed in a line.
• A few of the lamellae are linked to the cell membrane.
• The lamellar whorl is seen in Nitrobacter and nitrogen monas and in Nitrococcus.
• The vesicles form through tubular accretion and invagination of plasma membrane.
• The vesicle’s structure is broken due to constriction occurring at an the same distance. The constriction is not responsible for an entire separation between tubules.
• Spherical vesicles with a tight-packed spherical observed within Chromatium as well as Rhodospirillum rubrum.
• In certain purple bacteria, the Vesicular bodies are flattened before being placed on regular plates, similar to thylakoids.
• Salton as well as Owen (1976) Have proposed that mesosomes form by vascularization of outside of the bilayer of lipids.
• But, they are particular cells’ membrane proteins, and the proteins differ from those of the cell membrane.

Functions of Mesosomes

1. Electron transport, phosphorylation and oxidation-reduction reactions.

While the majority of respiratory activities occur within the membranes of the peripheral part of bacteria, the oxidoreductase and cytochrome activities are primarily found in mesosomes. Dehydrogenase activity as well as the existence of cytochromes within mesosomes are evidence that mesosomes play a role in electron transport processes as well as the redox reaction. A few studies have since shown that mesosomes are key sources of respiratory and oxidative metabolic processes in bacteria. However, whether any particular activities, like dehydrogenase or respiratory, is located only or primarily in mesosomes , is still unknown and need to be studied further.

2. Replication and apportionment of DNA. 

Mesosomes play a crucial role in cell division, as they play a role in DNA synthesizing and separation. When cells divide mesosomes function as a mediator, connect nucleoid material and peripheral membranes. Mesosomes that connect them push nucleoid substances towards the hypertonic medium’s membrane when mesosome extrusion occurs.

3. Septum formation as well as cytoderm and cytomembrane syntheses.

The evidence from morphological and biochemical studies has revealed that mesosomes play an active role involved in the formation of plasma membranes and cells’ wall creating a cross-wall and septum. Mesosomes play a role in the formation of septums and could be a source of the initiators. But, there is no evidence to have shown that these reactions are limited to mesosomes.

References

• Greenawalt JW, Whiteside TL. Mesosomes: membranous bacterial organelles. Bacteriol Rev. 1975;39(4):405-463. doi:10.1128/br.39.4.405-463.1975
• Burdett, I. D. J. (1972). Bacterial mesosomes. Science Progress (1933- ), 60(240), 527–546. http://www.jstor.org/stable/43420194
• Xin Li; Hanqing Q. Feng; Xinyue Y. Pang; Hongyu Y. Li (2008). Mesosome formation is accompanied by hydrogen peroxide accumulation in bacteria during the rifampicin effect. , 311(1-2), 241–247. doi:10.1007/s11010-007-9690-4 
• Herbert Voelz (1965). Formation and structure of mesosomes in Myxococcus xanthus. , 51(1), 60–70. doi:10.1007/bf00406850 
• Li, Xin; Yang, Li Peng; Zhu, Wen Xue; Pang, Xin Yue; Feng, Han Qing (2014). Mesosomes, Unique Membranous Structures in Bacteria. Advanced Materials Research, 894(), 316–320. doi:10.4028/www.scientific.net/AMR.894.316
• https://en.wikipedia.org/wiki/Mesosome
• https://www.britannica.com/science/mesosome-beardworm-body-structure
• https://journals.asm.org/doi/pdf/10.1128/br.39.4.405-463.1975
• https://www.slideshare.net/AshfaqAhmad52/bacterial-morphology-67925132
• https://www.biologydiscussion.com/bacteria/definition-of-mesosomes-bacteria/64975