Filament Systems

Ris, H. (1985). The cytoplasmic filament system in critical point-dried whole mounts and plastic-embedded section. J. Cell Biol. 100,1474-1487. 

Inside the typical smooth muscle cell, the cytoplasmic filaments course around the nuclei filling most of the cytoplasm between the nuclei and the plasma membrane. There are two filamentous systems in the smooth muscle cell which run lengthwise through the cell. The first is the more intensively studied actin-myosin sliding filament system. This is the system to which a consensus of investigators attribute most of the active mechanical properties of smooth muscle. It will be discussed in detail below. The second system is the intermediate filament system which to an unknown degree runs in parallel to the actin-myosin system and whose functional role has not yet been completely agreed upon. The intermediate filaments are so named because their diameters are intermediate between those of myosin and actin. These very stable filaments are functionally associated with various protein cytoarchitectural structures, microtubular systems, and desmosomes. Various proteins may participate in the formation of intermediate filaments, e.g., vimentin. 

The analytic validity of an abstract parallel elastic component rests on an assumption. On the basis of its presumed separate physical basis, it is ordinarily taken that the resistance to stretch present at rest is still there during activation. In short, it is in parallel with the filaments which generate active force. This assumption is especially attractive since the actin-myosin system has no demonstrable resistance to stretch in skeletal muscle. However, one should keep in mind, for example, that in smooth muscle cells there is an intracellular filament system which runs in parallel with the actin-myosin system, the intermediate filament system composed of an entirely different set of proteins, (vimentin, desmin, etc.), whose mechanical properties are essentially unknown. Moreover, as already mentioned, different smooth muscles have different extracellular volumes and different kinds of filaments between the cells. 

It is now believed that the most critical component in the gas phase mixture is atomic hydrogen, and indeed, this reactive atom drives the whole chemical system. Two hydrogen atoms are made when a hydrogen molecule (H ) splits apart. In a hot filament system, the thermal energy... 

The role of the IF, and particularly the keratin filament system, in resisting the forces of mechanical stress has been well established. However, IFs also play a role in countering metabolic stress. Perhaps the best example is the cytoprotective role played by the simple epithelial keratins, K8/18. However, vimentin, desmin, peripherin, GFAP, the lens proteins phakinin, and filensin and other keratins have also been shown to associate with members of the small heat shock protein (HSP) family, including HSP27 and aB-crystallin (reviewed in Coulombe and Wong, 2004 Marceau et al., 2001 Nicholl and Quinlan, 1994). 

Here,, is the mobility coefficient, while L22 is a generalized mobility relating ATP consumption and the chemical potential difference, and /., 2 and L2] are the mechano-chemical coupling coefficients. A given motor/filament system can work in different regimes, and in a regime where the work is performed by the motor, efficiency is defined by... 

A sarcomere is the basic unit of a muscle s cross-striated myofibril (Figure 17.4). Sarcomeres are the motor units of skeletal and cardiac muscle. They are multi-protein complexes composed of three different filament systems ... 

The thick filament system, which comprises myosin protein, connected from the M-line to the Z-disc by titin (connectin), and myosin-binding protein C, which binds at one end to the thick filament and at the other to actin. 

The M-band proteins myomesin, as well as M-protein, cross-link the thick-filament system (myosins) and the M-band part of titin (the elastic filaments). 

Staufenbiel, M. and Deppert, W. (1982) Intermediate filament systems are collapsed onto the nuclear surface after isolation of nuclei from tissue culture cells. Exp. Cell Res. 138, 207-214. 

A pyrolysis unit usually consists of a controller and the pyrolyser itself. The controller provides the appropriate electrical energy needed for heating. A simplified scheme of a pyrolyser (based on the design of a flash heated filament system made by CDS Inc.) is shown in Figure 4.1.1. 

FIGURE 4.1.1. The simplified scheme of a pyrolyser (based on the design of a heated filament system made by CDS Inc.). 

The same polymer was also analyzed for less volatile components by performing the pyrolysis off line at 600 C in a filament system followed by off-line derivatization with BSTFA. The silylated pyrolysate was analyzed by GC/MS on a DB-5 column (60 m long, 0.32 mm i.d., 0.25 urn film thickness). For this analysis the GC separation was done using a temperature gradient between 50° C and 300° C. The chromatogram is shown in Figure 11.3.2. 

J.G. Lieber and R.M. Evans, Disruption of the vimentin intermediate filament system during adipose conversion of 3T3-L1 cells inhibits lipid droplet accumulation, J. Cell. Sci., 1996, 109, 3047-3058. 

This chapter discusses muscle, an actin filament system, and cilia, a microtubule system. These do not typify all contractile systems. In some actin filament systems, movement occurs in the absence of myosin, being driven... 

This study is only an approximation of the moving filament system. The movement of the filament in a continuous system averages the effects of all the parameters so that the filament sample is prepared in a uniform manner. The edge effects noted on the filament situated under the electrodes would not be evident in a continuous system. A typical deposit is shown in Figure 3. 

There are three types of muscle cells smooth, skeletal, and cardiac. In all types of muscle, contraction occurs via an actin myosin sliding filament system, which is regulated by oscillations in intracellular calcium levels. 

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