Nuclear Permeability

Fixation in glutaraldehyde produces better morphology, but induces a great deal of autofluorescence, and limits cytoplasmic and nuclear permeability. A protocol utilizing glutaraldehyde followed by borohydride treatment has been previously described that is applicable also for electron microscopy of cultured cells (4). Some areas of the cell are relatively impermeable with this approach, but this is an excellent choice of fixative protocol for microtubule morphology. 

The ultrastructure of the nuclear membrane brings up the important matter of its permeability. Unfortunately, at present, this problem cannot be presented in the light of uncontroversial, factual evidence. The questions raised by nuclear permeability pertain to only a period of cellular life. The nuclear membrane disappears at the end of prophase and remains absent during anaphase and metaphase until telophase. 

Several mechanisms are involved in the permeability through Caco-2 cells. In order to obtain a more pure measure of membrane permeability, an experimental method based on ghost erythrocytes (red blood cells which have been emptied of their intracellular content) and diffusion constant measurements using nuclear magnetic resonance (NMR) has been proposed [108]. 

For the pressure studies, two phase" compact ion behavior is observed with an inflection point between 7 and 11 atms. For the aqueous solution studies, the hydraulic permeability K and the g-ratio are hardly effected by solute type (within experimental error). The solute diffusive permeability however, varies with solute type in good qualitative agreement with free energy parameters, infrared overtone shifts, and spin echo and continuous wave nuclear magnetic resonance spectroscopy results from the literature. 

Zoghhi, S.S., How, J.S., Yasuno, F., Hong, J., Tuan, E., Lazarova, N., Gladding, R.L., Pike, V.W and Irmis, R.B. (2008) IIC-loperamide and its N-desmethyl radiometahohte are avid substrates for brain permeability-glycoprotein efflux. Journal of Nuclear Medicine, 49, 649-656. 

Degeneration Mitochondrial permeability transition with membrane depolarization, cytochrome c release, and mitochondrial swelling and fragmentation activation of caspases and cell death pathway, endonuclease fragmentation of DNA with chromatin and nuclear condensation phosphatidyserine exposure on cell surface cytoskeletal disruption with membrane blebbing... 

Here, h denotes Planck s constant h divided by 27i, and /zq is the permeability of vacuum. I and 5 are the nuclear spins of the resonating spins I and non-resonating spins S, respectively. Ni and Ns denote the numbers of resonating and nonresonating nuclei in the sample, respectively ys the magnetogyric ratio of the nonresonating spins S, and and ryj- the internuclear distances. 

These are the Fourier components of the polarization vector which are connected with the oscillations of the ions that are present in eqns. (44)-(46). In addition to this polarization which results from the motion of the nuclei, purely electronic polarization (i.e. the polarization of electrons at equilibrium positions of the nuclei) is also of importance. In the frequency region below the optical range, the purely electronic polarization can be expressed through the optical dielectric permeability (i.e. the dielectric permeability corresponding to the frequencies which are less than those in the optical absorption region, but exceed those of the nuclei vibrations). Optical frequencies considerably exceed those of the nuclear vibrations therefore, in the optical frequency region the nuclei do not, in practice, contribute to polarization. The connection of the Fourier component of purely electronic polarization with that of the induction of the electric field has the usual form... 

Heat treatment, on the other hand, elevated cytoplasmic immunoreactivity of Bcl-2. However, nuclear and mitotic Bcl-2 immunoreactivity was clearly present when these cells were fixed with formaldehyde (3.6%), followed by postfixation with methanol for 10 min at -20°C. Treatment with ice-cold methanol makes the cell membrane permeable, allowing antibody access to intranuclear antigens without protein relocalization. Extensive protein crosslinking with formaldehyde is required for maintenance of intranuclear Bcl-2 immunoreactivity. In contrast to Bcl-2, Bax immunoreactivity was detected in nuclear and cytoplasmic compartments regardless of the duration of formaldehyde fixation used. 

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