Red Dye Uptake in Yeast Cells
A study of the osmoregulatory capabilities in Nereis virens and Phascolopsis gouldi: osmoregulators vs. osmoconformers
Introduction
Water is essential for life as we know it on this planet, and according to Campbell et al. (1999), water is the major constituent of cells. Reactions vital to life occur under aqueous conditions in the body and cells of all organisms, and the concentrations of reactants necessary for these reactions depend upon the amount of water present (Pough et al. 2004). By the process of osmosis, water moves from areas of lower to areas higher concentration across a water- permeable membrane, like a cell membrane (Nybakken and Bertness 2005). In order to maintain the proper concentrations of reactants and ions within the body, organisms osmoregulate, but organisms vary in their osmoregulatory capabilities (Brusca and Brusca 2003). Osmoregulators, as the name suggests, preserve their internal osmotic concentration regardless of the osmotic concentration of the surrounding environment, and contrastingly, the internal osmotic concentration of an osmoconformer changes with and conforms to the environmental osmotic concentration (Nybakken and Bertness 2005).
Understanding how organisms cope with the physical stresses pertaining to water adds an important dimension to our comprehension of marine biology. Most marine invertebrates maintain bodily fluids that match the osmotic concentration of the surrounding seawater, and in the open ocean and many benthic environments where salinity is relatively constant, the isosmotic marine invertebrates encounter little osmotic stress. However, in estuaries and intertidal regions, salinity fluctuates with changing environmental conditions (for example, the addition of fresh water from precipitation, the loss of water to evaporation, and fluctuating fresh water input from rivers), and the organisms inhabiting these regions of unstable salinity face greater osmotic stresses than organisms in areas of
Introduction
Water is essential for life as we know it on this planet, and according to Campbell et al. (1999), water is the major constituent of cells. Reactions vital to life occur under aqueous conditions in the body and cells of all organisms, and the concentrations of reactants necessary for these reactions depend upon the amount of water present (Pough et al. 2004). By the process of osmosis, water moves from areas of lower to areas higher concentration across a water- permeable membrane, like a cell membrane (Nybakken and Bertness 2005). In order to maintain the proper concentrations of reactants and ions within the body, organisms osmoregulate, but organisms vary in their osmoregulatory capabilities (Brusca and Brusca 2003). Osmoregulators, as the name suggests, preserve their internal osmotic concentration regardless of the osmotic concentration of the surrounding environment, and contrastingly, the internal osmotic concentration of an osmoconformer changes with and conforms to the environmental osmotic concentration (Nybakken and Bertness 2005).
Understanding how organisms cope with the physical stresses pertaining to water adds an important dimension to our comprehension of marine biology. Most marine invertebrates maintain bodily fluids that match the osmotic concentration of the surrounding seawater, and in the open ocean and many benthic environments where salinity is relatively constant, the isosmotic marine invertebrates encounter little osmotic stress. However, in estuaries and intertidal regions, salinity fluctuates with changing environmental conditions (for example, the addition of fresh water from precipitation, the loss of water to evaporation, and fluctuating fresh water input from rivers), and the organisms inhabiting these regions of unstable salinity face greater osmotic stresses than organisms in areas of
Cited: Brusca, R.C., and G.J. Brusca. 2003. Invertebrates (second edition). Sinauer Associates, Inc., Sunderland, MA, USA. Campbell, N.A., J.B. Reece, and L.G. Mitchell. 1999. Biology (fifth edition). Benjamin Cummings, Menlo Park, CA, USA. Gosner, K.L. 1978. A field guide to the Atlantic seashore. Houghton Mifflin Company, New York, NY, USA. Moore, D.S. and G.P. McCabe. 2003. Introduction to the practice of statistics (fourth edition). Nybakken, J.W., and M.D. Bertness. 2005. Marine biology: an ecological approach (sixth edition). Benjamin Cummings, San Francisco, CA, USA. Pechenik, J.A. 2001. A short guide to writing about biology (fourth edition). Addison-Wesley Educational Publishers, Inc., New York, NY, USA. Pough, F.H., R.M. Andrews, J.E. Cadle, M.L. Crump, A.H. Savitzky, and K.D. Wells. 2004.