Senescence programmed

When the light microscope (LM) alone is not sufficient to study a system, the binding of an electron-dense ligand to an antibody facilitates the use of an EM. There are times when, in addition to EM study, immunoelectron microscopic analysis is necessary. Observed anatomical changes often lead to inquiries on the molecular events. This proved true in the case of the report by Inada et al. (22) in which they described a three-dimensional analysis of the senescence program in rice (Oryza sativa L.) coleoptiles. Immunoelectron microscopy was used to determine the behavior of cellular DNA during senescence. The procedure employed by the investigators is detailed below. 

InadaN, Sakai A, Kuroiwa H, Kuroiwa T. Three-dimensional analysis of the senescence program in rice (Oryza sativa L.) coleoptiles. Planta 1998 206 585-597. 

Hadfield, K.A. and Bennett, A.B., Programmed senescence of plant organs, Cell Death Differentiation, 4, 662-670, 1997. 

The right-hand column indicates the main sources of programming, the psychological influences on the person. The main stages are infancy, childhood, adolescence, adulthood, and senescence. 

Chen Q,Ames BN (1994) Senescence-like growth-arrest induced by hydrogen peroxide in human diploid fibroblast F65 cells. Proc Natl Acad Sci USA 91 4130-4134 Zamzani NT, Hirsch B, Dallaporta P, Petit X, Kroemer G (1997) Mitochondrial implication in accidental and programmed cell death apoptosis and necrosis. J Bioenerg Biomembr 29 185-193... 

Dangl JL, Dietrich RA, Thomas H (2001) Senescence and Programmed Cell Death. In Buchanan BB, Gruissem W, Jones RL (eds.) Biochemistry and Molecular Biology of Plants, p. 1044. Am Soc Plant Physiol, Rockville, MD, USA... 

The disintegration of the old macronucleus echoes what must have been a pivotal moment in evolution. For the first time, we encounter DNA that is deliberately not transmitted to the next generation. Is this the origin of the soma and of senescence It certainly is, according to Clark "it is in the programmed death of the macronuclei of early eukaryotes like Paramecium that our own corporeal deaths are foreshadowed." Whether... 

The impression that ageing is programmed is strongest in animals that undergo catastrophic senescence. The most famous example is the Pacific salmon, though there are several others, including mayflies, marsupial mice (Antechinus) and the octopus Octopus hummelinckL Pacific salmon hatch... 

---