[
J Cell Biol,
2001]
Cytologists have long observed that individual eukaryotic species segregate their chromosomes in one of two apparently different ways. Monocentric chromosomes attach to microtubules at a particular region (the centromere) and move toward the pole during anaphase with the centromere leading. In contrast, holocentric chromosomes bind to microtubules along their entire length and move broadside to the pole from the metaphase plate. Holocentric chromosomes are scattered throughout the plant and animal kingdoms, and may be products of convergent evolution. Alternatively, the ancestral eukaryotic chromosome may have been holocentric, in which case the restriction of kinetic activity to a specialized region must have been an evolutionary event that occurred again and again.
[
Science,
1994]
Like people, cells die in different ways: accident, murder, old age, even suicide. In fact, cellular suicide isn't just a curiosity, it's necessary for the health of the organism. During embryonic development, for example, it helps weed out superfluous nerve cells, as well as immune cells that might attack and damage the body's own tissues. Like a spy-plane pilot who carries a little vial of poison under his seat in case he's captured, cells carry in their nuclei a genetic program for suicide that can be set in motion, should the cell receive orders to self-destruct. Now, after years of eluding researchers, the genes that carry out the suicide program are coming into the light...
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Worm,
2016]
The hypoxic response is a well-studied and highly conserved biological response to low oxygen availability. First described more than 20 y ago, the traditional model for this response is that declining oxygen levels lead to stabilization of hypoxia-inducible transcription factors (HIFs), which then bind to hypoxia responsive elements (HREs) in target genes to mediate the transcriptional changes collectively known as the hypoxic response.(1,2) Recent work in C. elegans has forced a re-evaluation of this model by indicating that the worm HIF (HIF-1) can mediate effects in a cell non-autonomous fashion and, in at least one case, increase expression of an intestinal hypoxic response target gene in cells lacking HIF-1.
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Genome Res,
2001]
The scientific method, and genetic analysis in particular, is based upon identifying variations between individuals of the same species. The study of Jones et al. in this issue reveals variation in transcript abundance between two developmental stages of the nematode Caenorhabditis elegns. In this case, the variation is not genetically specified ut is induced bt the environment as part of a shift to an alternate developmental form, the daur larva. In this type of whole-genome analyses, it is assumed that such studies would reveal differences in transcript abundance that would be casusall associated with distinct molecular and morphological transformations driving development. Much of this paper is conjecture about how the observed differences in transcriipt abundance specify observed differences in longevity(or, more precisely, in mortality rate).