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NORMAL LIFESPAN. “We suggested that the finite capacity of normal cells to replicate was a reflection of ageing or longevity determination at the cell level, an idea that received substantial support in subsequent years.” https://lnkd.in/esfPTAR View in LinkedIn

MORTAL NORMAL CELLS. “By mid century the immortality of cancer cells was demonstrated in vitro, followed by the finding that, contrary to prevailing belief, cultured normal cells are mortal.” https://lnkd.in/esfPTAR View in LinkedIn

TUMOR IMMORTALITY. “Most cancer cell populations can be distinguished from normal cells by a progressive acquisition of properties that includes immortality. This was first demonstrated in the early part of the twentieth century by the finding that rodent tumours could be serially transplanted indefinitely.” https://lnkd.in/esfPTAR View in LinkedIn

REPLICOMETER. “Forty years ago we showed that cell mortality and immortality are inextricably linked to longevity determination, ageing and cancer. We suggested that a counting mechanism existed in normal cells and that has now been identified as telomere attrition. This replicometer, in combination with the discovery of the enzyme telomerase, has gone very far in explaining why most normal somatic cells have a finite capacity to replicate both in vivo and in vitro and how immortal cancer cells circumvent this inevitability.” https://lnkd.in/esfPTAR View in LinkedIn

BACTERIAL MORTALITY under some conditions."Bacteria were traditionally thought to have a symmetrical binary fission without a clear distinction between soma and germ-line, being thus considered as immortal biological entities. Yet it has been recently described that bacteria also undergo replicative aging (RA). That is, they exhibit finite replicative abilities under good conditions to growth." https://lnkd.in/esfYya9 View in LinkedIn

IMMORTAL BACTERIA. "Bacteria are said to be biologically immortal, but only at the level of the colony. An individual bacterium can easily die. The two daughter bacteria resulting from cell division of a parent bacterium can be regarded as unique individuals or as members of a biologically "immortal" colony. The two daughter cells can be regarded as "rejuvenated" copies of the parent cell because damaged macromolecules have been split between the two cells and diluted. In the same way stem cells and gametes can be regarded as "immortal"." http://en.m.wikipedia.org/wiki/Biological_immortality View in LinkedIn

SO ENDS this second weekend contemplating the curious orchid family. The exacting fieldwork that has gone into teasing out these nuanced features of orchid deceptive reproduction are exemplars of excellent observation skills and hypothesis testing, in often uncomfortable conditions. The results, spread over hundreds of publications, are quite dazzling. The orchid has proved Darwin to be right. They were worth the effort. View in LinkedIn

POLLINATION LIMITED. "We reaffirm that orchids are primarily pollination limited, the severity of which is affected by resource constraints. Fruit set is higher in temperate than in tropical species, and in species which offer pollinator rewards than those that do not. Reproductive success is skewed towards few individuals in a population and effective population sizes are often small." https://lnkd.in/dXXbjhY View in LinkedIn

FAILSAFES. "In the absence of an effective pollinator some orchids use autopollination (10–15%) and very rarely apomixis (asexual propagation). Unlike many other flowering plants, orchids place the pollen on the pollinators in specific microsites to reduce cross pollination between species rather than using chemical inhibition. As a result most orchids are self compatible, with self-incompatibility being rare." http://www.sciencedirect.com/science/article/pii/S0960982208001723 View in LinkedIn

THE INBREEDING LINE. "Recent population genetic and phylogenetic investigations suggest gene-flow within subgeneric clades, but pollinator-mediated selection may maintain species-specific floral traits." http://link.springer.com/article/10.1007/s00114-005-0636-y View in LinkedIn