User:Danlee28/sandbox

This is my Wikipedia Page!
This is my first time writing, but I am a biology student at Boston College!

Hydrostatic pressure is the pressure that is exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity. For many deep sea fish in the bathypelagic and beyond, the hydrostatic pressure that these organisms experience increases by one atmosphere for every 10 meters deeper in depth. For a fish at the bottom of the bathypelagic zone, this equates to the fish withstanding around 400 atmospheres of hydrostatic pressure. There a variety of adaptations that deep sea fauna possess, on a cellular level and physiological level, that allow them to thrive in an environment of great pressure. These physiological adaptations act as a boundary that limits the depth that shallow-species can penetrate. High levels of external pressure have a great effect on metabolic processes and biochemical reactions. The equilibrium of many chemical reactions can be disturbed by pressure, and thus reactions inducing volume changes are susceptible to pressure. When a volume increase takes place during the process, pressure will inhibit the process. Water, a key proponent in many biological processes, is very susceptible to volume changes. Thus, enzymatic reactions that induce changes in water organization effectively change the system's volume. Proteins that are responsible for catalyzing many reactions are typically held together by a culmination of weak bonds and usually involve an increase in volume during formation. To adapt to this change, the protein structure and reaction criteria of deep sea fish have been adapted to withstand pressure in order to perform reactions in these conditions. In high pressure environments, cellular bilayer membranes experience a loss of fluidity. Therefore, deep-sea cellular membranes favor phospholipid bilayers with a higher proportion of unsaturated fatty acids, which induce a higher fluidity than their sea-level counterparts.

Deep sea species exhibit a lower change of entropy and enthalpy, since a high pressure and low temperature environment seem to favor negative enthalpy changes and a reduced dependence on entropy-driven reactions, compared to that of surface level organisms. From a structural standpoint, globular proteins of deep sea fish the tertiary structure of G-actin is relatively rigid compared to that of surface level fauna. Proteins of deep sea fish are structurally modified is apparent from the observation that actin from the muscle fibers of deep sea fishes are extremely heat resistant; a similar characteristic to those of desert lizards. These proteins are structurally strengthened by modification of the bonds in the tertiary structure of the protein which also happen to induce high levels of thermal stability. Proteins are structurally strengthened to resist pressure by modification of bonds in the tertiary structure. Therefore, high levels of hydrostatic pressure, similar to high body temperatures of thermophilic desert reptiles, favor rigid protein structures.

Na+/K+ -ATPase is an lipoprotein enzyme that plays a prominent role in osmoregulation and is heavily influenced by hydrostatic pressure. The inhibition of Na+/K+ -ATPase is due to increased compression due to pressure. The rate-limiting step of the Na+/K+ -ATPase reaction induces an expansion in the bilayer surrounding the protein, and therefore an increase in volume. An increase in volume makes Na+/K+ -ATPase reactivity susceptible to higher pressures. Even though the Na+/K+ -ATPase activity per gram of gill tissue is lower for deep sea fishes, the Na+/K+ -ATPases of deep sea fishes exhibit a much higher tolerance of hydrostatic pressure compared to their shallow-water counterparts. This is exemplified between the species of the genus Coryphaenoides (around 2000m deep) and its hadalpelagic counterpart C. armatus (around 4000m deep), where the Na+/K+ -ATPases of C. armatus are much less sensitive to pressure. This resistance to pressure can be explained by adaptations in the protein and lipid moieties of Na+/K+ -ATPase.