The ageing, growth and death of cells

What is the role and nature of programmed cell death in phytoplankton ecology?

“…This assumption is confounded by the considerable metabolic heterogeneity of both natural and laboratory microalgal populations, as revealed through physiological assays (Veldhuis et al, 2001;Brussaard et al, 2001;Agustı´2004). Added to this, kinetic analysis shows that populations of symmetrically dividing cells can simultaneously contain dividing, non-dividing and dying cells whilst showing exponential growth, provided that the death rate is constant (Sheldrake, 1974). Thus, considerable metabolic heterogeneity is possible in phytoplankton populations, although little is known about it, and what does exist is likely to have been overlooked up to now.…”

Autophagy, organelles and ageing

“…Most dividing cells, such as stem and progenitor cells, as well as short-lived postmitotic cells that differentiate from those cells (eg enterocytes and peripheral blood cells) remain in good shape, even at the end of a normal lifespan (reviewed in [3]). This is because repetitive division of stem and progenitor cells results in a continuous dilution of damaged macromolecules and organelles (here referred to as biological 'garbage' or 'waste'), while differentiated cells are frequently replaced and therefore do not accumulate any considerable amount of such 'garbage' [4,5]. Long-lived postmitotic cells, in contrast, are only rarely reinstated from stem cells [6,7], a fact that apparently determines their profound alterations by age ( Figure 1).…”

Epidemiología genética sobre las teorías causales y la patogénesis de la diabetes mellitus tipo 2

“…Sheldrake 71 propuso a la lipofuscina como un producto perjudicial. Respecto al compuesto que ha mantenido diversos debates sobre si es citotóxico para la célula β, este es el péptido amiloide o amilina.…”