Diatom physiology
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pH regulation in diatoms
pH regulation in diatoms
Diatoms are major primary producers (remove carbon dioxide and synthesize carbon sugars and proteins) in the ocean. The regulation of cellular pH (acidity) is essential to homeostasis and maintaining all functions of the cell. During my PhD, I studied the role of pH regulation in diatoms by the V-type H+-ATPase (VHA; proton pump) in the labs of Dr. Martin Tresguerres and the late Dr. Mark Hildebrand. This proton pump is found in all eukaryotic life (algae to humans) and modifies pH inside and outside of cells. Using genetic tools I was able to fluorescently label VHA with GFP (green fluorescent protein) an demonstrate how VHA can move within the cell to control pH and serve in multiple physiological functions.
This time-lapse video captures the movement of the VHA (green) from vacuoles to the silica deposition vesicles (SDVs) of a dividing cell. The SDV become acidified by VHA which is demonstrated by the accumulation of PDMPO (magenta) in the newly biomineralized cell walls. The video ends with the separation of the two daughter cells and dispersion of VHA.
Silica biomineralization
Silica biomineralization
Diatom cells are encased in glass shells call frustules which are synthesized in special compartments inside the cell called SDVs. We showed that the VHA is responsible for acidfying SDVs to promote the careful biomineralization of their cell walls. Read about it here!
Photosynthesis
Photosynthesis
Diatoms contribute a major portion of earth's photosynthesis thanks to a highly efficient carbon concentrating mechanism (CCM). We discovered that VHA is present around chloroplasts to functions as a part of the diatom CCM and linked it to the photosymbiotic evolution of diatoms. Read article here!
Vacuole dynamics
Vacuole dynamics
Vacuoles act as a sort of 'room of requirement' in the cell serving as a place for storage of excess carbon and nitrogen, as well as serving as a source of bouyancy during vertical migrations in the ocean. As the name 'vacuolar' implies, we showed that VHA is constitutively found in vacuolar membranes (green). Read my interview on Pg. 18 of the July 2024 issue of SEB magazine here.
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