Postnatal differentiation of the Golgi apparatus and the dendrites of Purkinje cells of the rat cerebellum

The Physiological Functions of the Golgin Vesicle Tethering Proteins

The golgins comprise a family of vesicle tethering proteins that act in a selective manner to tether transport vesicles at the Golgi apparatus. Tethering is followed by membrane fusion to complete the delivery of vesicle-bound cargo to the Golgi. Different golgins are localized to different regions of the Golgi, and their ability to selectively tether transport vesicles is important for the specificity of vesicle traffic in the secretory pathway. In recent years, our mechanistic understanding of golgin-mediated tethering has greatly improved. We are also beginning to appreciate how the loss of golgin function can impact upon physiological processes through the use of animal models and the study of human disease. These approaches have revealed that loss of a golgin causes tissue-restricted phenotypes, which can vary in severity and the cell types affected. In many cases, it is possible to attribute these phenotypes to a defect in vesicular traffic, although why certain tissues are sensitive to loss of a particular golgin is still, in most cases, unclear. Here, I will summarize recent progress in our understanding of golgins, focusing on the physiological roles of these proteins, as determined from animal models and the study of disease in humans. I will describe what these in vivo analyses have taught us, as well as highlight less understood aspects, and areas for future investigations.

Morphometric study of the interphase nucleus in some radiosensitive and radioresistant mammalian cells

The radiosensitive cell populations, such as resting lymphocytes from thymus, spleen, lymph node and blood, have much smaller nuclei (Vn (nuclear volume) approximately 20 to 70 microns3) compared to radioresistant G0 cells from non-lymphoid tissues (liver, kidney, brain, heart; Vn approximately 75 to 2700 microns3). It is suggested that radiation-induced disorganization of nuclear structures and cell pycnosis (interphase death) are promoted in G0 lymphocytes because in normal physiological conditions their nuclei assume a higher degree of chromatin condensation. In contrast, dispersion of chromatin into larger nuclear volumes, such as those of most non-lymphoid G0 cells, may hinder or delay radiation-induced cell death.