[
WormBook,
2006]
Optical methods provide a noninvasive way to monitor the activity of neurons and muscles in C. elegans. Although optical techniques are of use in many experimental systems, they are of particular interest for C. elegans researchers. Worms are optically transparent, and thus can be imaged while fully intact, and a variety of genetically encoded indicators are available which can be targeted to cells of interest with appropriate promoters. Optical calcium indicators appear to provide a good indirect measure of the activity of neurons and muscles. This chapter reviews the principles of operation of some common genetically encoded indicators, describes the microscopy equipment and image analysis needed to optically measure activity, discusses general principles and pitfalls of applying optical methods in biological samples, and finally gives example protocols for imaging calcium in specific muscles and neurons.
[
Ernst Schering Res Found Workshop,
2000]
The proliferation of cells is an integral part of development and tissue homeostatsis in multicellular animals(reviewed by Raff 1996; Folletee and O'farrel 1997). Two opposing processes, the division of cells on one hand and the programmed death of cells on the other hand, determine the overall rate of cell proliferation, The proper regulation of these two physiological processes is therefore a crucial aspect of development and of tissue homeostatsis(reviewed by Edgar and Lehner 1996; Shrr 1997;Jacobson et al. 1997). While the importance of the process of cell division has long been recognized, the role and extent of programmed cell death, or apoptosis, has only been realized within the last decades (Glucksmann 1950; Kerr et al. 19972). Massive programmed cell death occurs, for instance, during the development of the nervous system and in the immune system: more than 50% on all neurons and oligodendrocytes formed in the periperal and central vertebrate nervous system undergo programmed cell death neurogenesis...
[
Proc Natl Acad Sci U S A,
1997]
Apoptosis, also called programmed cell death, has attracted great attention in recent years. After its discovery by Carl Vogt in 1842, apoptosis research was dormant for more than a century. Its rediscovery in the second half of this century, and the coining of the term apoptosis in 1972 by Kerr, Wyllie, and Currie, ignited an unparalleled interest in this field of science. The number of publications related to apoptosis has been growing exponentially every year ever since. This is mainly due to three major advances, two of which have been made recently and one that is currently seen. First, studies with the small nematode Caenorhabditis elegans have identified a number of apoptosis regulating genes--the first evidence that cell death is an active process under genetic control. Many of these genes have mammalian homologs that, like their worm counterparts, seem to regulate mammalian apoptosis. Second, elucidation of the signal transduction pathways of apoptosis has lead especially to the identification of specific death signaling molecules such as a new family of cysteine proteases, the caspases. Third, it has now become clear that many diseases are characterized by dysregulation of apoptotic programs. Many of these programs involve a family of receptors and their ligands, the death receptor/ligand family. The hope now is to interfere with apoptosis regulation in these systems and to develop new therapeutic concepts.