GAS VACUOLES
· Gas vacuole, a structure that provides buoyancy to
some aquatic Prokaryotes.
· Gas vacuoles are present in many Photosynthetic
bacteria and a few other Aquatic prokaryotes such as Halobacterium (a
salt-loving archaeon) and Thiothrix (a filamentous bacterium).
GAS VESICLES
· Gas vacuoles are aggregates of enormous numbers of Small,
Hollow, Cylindrical or Conical shaped structures called Gas vesicles.
·
Gas vesicles in
different species vary in length from about 300 to more than 1000 nm and in
width from 45 to 120 nm.
·
Gas vesicles
may number from a few to hundreds per cell.
· Gas vesicle walls are composed entirely of two small Protein
sub-units (Major protein – Gvp A and Minor protein – Gvp C). These protein sub-units
assemble to form a rigid enclosed cylinder that is hollow and impermeable to
water but freely permeable to atmospheric gases.
Functions of Gas Vesicles
· Aquatic Prokaryotes with Gas vesicles can regulate
their buoyancy to float at the depth necessary for proper a) Light intensity;
b) Oxygen concentration and c) Nutrient levels.
·
Phototrophic aquatic
prokaryotes in particular can benefit from Gas vesicles because they allow
cells to adjust their vertical position in a water column to sink or rise to
regions where conditions (for example, Light intensity) are optimal for
Photosynthesis.
· Gas vesicles can be used to maintain optimum salinity
by positioning the organism in specific locations in a stratified body of water
to prevent Osmotic Shock. The ability to synthesize Gas vesicles is one of
many strategies that allow Halophilic organisms to tolerate environments with
high Salt content.
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