Cells, biological muscle

Clegg, C.H., Linkhart, T.A, Olwin, B.B. and Hauschka, S.D. (1987) Growth factor control of skeletal muscle differentiation occurs in Grphase and is repressed by fibroblast growth factor. Journal of Cell Biology 105, 949-956. 

Jasmer, D.P. (1993) Trichinella spiralis infected skeletal muscle cells arrest in G2/M is associated with the loss of muscle gene expression. Journal of Cell Biology 121, 785-793. 

Beardall, C.H. and Johnston, I.A. (1985). Lysosomal enzyme activities in muscle following starvation and refeeding in the saithe Pollachius virens L.). European Journal of Cell Biology 39,112-117. 

Miyamoto T, Kakizawa T, and Hashizume K (1999) Inhibition of nuclear receptor signalling by poly(ADP-ribose) polymerase. Molecular and Cell Biology 19,2644-9. Miyoshi K, Egi Y, Shioda T, and Kawasaki T (1990) Evidence for in vivo synthesis of thiamin triphosphate by cytosolic adenylate kinase in chicken skeletal muscle./oMrnal... 

Consider a typical eukaryotic cell, for instance, a muscle cell. By weight, the cell is about 75% water. However, this estimate fails to convey the truly aqueous nature of the cell a far more realistic description is in terms of mole ratios. Because of the low molecular weight of water, the nominal 75% water translates into a very large number of moles of water relative to the number of moles of other cell constituents. Thus, the aqueous nature of the cell is better illustrated by noting that for every 20,000 water molecules there are only about 75 lipid molecules, 100 sodium, potassium, and chloride ions (with at most a few hundred other small molecules or ions), and only one or two protein molecules. By sheer numbers water molecules totally dominate, and in this perspective life is merely some complex biochemistry in an extensive matrix of water, stabilized by a few lipids and macromolecules. The two dominating factors in cell biology are thus, simply, water molecules and interfaces. 

Proteins are very important in biological systems as control and structural elements. Control fimctions of proteins are carried out by enzymes and proteinaceous hormones. Enzymes are chemicals that act as organic catalysts (a catalyst is a chemical that promotes but is not changed by a chemical reaction). Click here for an illustrated page about enzymes. Structural proteins function in the cell membrane, muscle tissue, etc. 

In keeping with their proposed cytoskeletal nature, IFPs initially were thought to serve a purely structural role in muscle cells. It was hypothesized that the function of these proteins was to keep other cytoplasmic proteins in proper relationship to one another, as well as to anchor the cytoplasmic contractile apparatus to the cell membrane. Flowever, subsequent developments in cell biology cast considerable doubt on this premise." The intermediate filaments are now known to serve a nucleic acid-binding function moreover, they are susceptible to processing by calcium-activated proteases and are substrates for cyclic adenosine monophosphate-dependent protein kinases. Thus, it has been proposed that all IFPs serve as modulators between extracellular influences governing calcium flux into the cell (and subsequent protease activation) and nuclear function at a transcriptional... 

A biological cell can be compared to a concentration cell for the purpose of calculating its membrane potential. Membrane potential is the electrical potential that exists across the membrane of various kinds of cells, including muscle cells and nerve cells. It is responsible for the propagation of nerve impulses and heart beat. A membrane potential is established whenever there are unequal concentrations of the same type of ion in the interior and exterior of a cell. For example, the concentrations of ions in the interior and exterior of a nerve cell are 400 mM and 15 mM, respectively. Treating the situation as a concentration cell and applying the Nemst equation, we can write... 

Another striking new direction of the QCM in the field of cell biology are motihty measurements based on noise analysis of the resonance frequency. When the cells move and crawl on the surface of the quartz plate the resonance frequency fluctuates as a direct consequence of the continuous assembly and disassembly of cell-substrate contacts during cell movement. Pax and coworkers have recently shown that the contraction of heart muscle cells can be easily recorded from the associated alterations of the resonance parameters [55]. We recently found that even in stationary cell layers without any open spaces that would allow for lateral migration, metaboUcally driven mi-cromotion can be recorded [56]. 

Fruhwirth, G O, Moumtzi, A, Loidl, A, Ingolic, E, and Hermetter, A, The oxidized phospholipids POVPC and PGPC inhibit growth and induce apoptosis in vascular smooth muscle cells, Biochim. Biophys. Acta - Molecular and Cell Biology of Lipids 1761 (2006) 1060-1069. 

FIGURE 5 Electron micrographs of negatively stained smooth muscle myosin filaments. Upper panel Smooth muscle myosin rod forms filaments with a distinct side-polar morphology. Lower three panels Myosin filaments formed by addition of 0.1A4 KCl to myosin minifilaments also show a side-polar appearance. Bar-0.1 p,m. Reproduced from the Journal of Cell Biology, 1987, 105, 3007-3019 by copyright permission of The Rockefeller University Press. 

Both males and females of all vertebrate species produce testosterone. The amount present in the male body is considerably greater than that present in the female body. Testosterone has a number of biological effects on the body, including an increase in the number of red blood cells and muscles cells and initiation of the development of male sex organs. It is also responsible for the development of secondary male sexual characteristics, such as the growth of body and facial hair, deepening of the voice, and increased sexual desire. Some less desirable effects are an increase in oiliness of the skin and acne. 

Fig. 1. Organization of filaments in smooth muscle cells. A. Vas deferens smooth muscle cell shown in transverse section. Thick filaments are surrounded by multiple thin filaments throughout the cytoplasm. Dense bodies ("db ) are round or oval in shape in transverse section but elongated in shape in oblique sections. Arrow point to intermediate filaments (10 nm) that surround the dense bodies. B. Longitudinal section of portal anterior mesenteric vein smooth muscle cell. Thin filaments (arrows) can be seen inserting on both sides of the dense bodies (db). Intermediate filaments (arrowheads) extend laterally from dense bodies and sometimes connect a series of dense bodies to form a chain. Magnification x 70,000. Reproduced from Bond and Somlyo (1982) The Journal of Cell Biology 95 403-413 with permission of Rockefeller University Press...

D. G. Hall, Combinatorial chemistry gives cell biology some muscle. Nature Bio-technology, 18 (2000), 261-262. 

Actin is a protein which is present in almost all eukaryotic cells and is Important in the cytoskeleton and cell motility. Muscle cdls are filled with arrays of actin and myosin filaments, adiich produce motion by AIT hydrolysis and sliding of the filaments. Polymerization of actin (C actin) to F>actin is widely studied In cell biology. 

The proton flux mediated electro-osmosis or in short proto-osmosis is the perimembrane and transfilament analog of Mitchell s (transmembrane) chemiosmotic theory and could be operating at the cellular and organismal levels in diverse dynamical processes (see Transport in Plants, Chapter 21 in this volume). If the phenomenon is experimentally verified in muscles and in other systems, the dynamic aspects of cell biology would become amenable to quantitative treatment using the principles of electrochemistry. 

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