nucleation

THEORY-1219: Buchnera's metabolism interlocks with its aphid host's: it makes the essential amino acids its host cannot from host-supplied glutamate and aspartate, depends on the host for the non-essential amino acids and its membrane phospholipids, and cannot live outside the bacteriocyte

1 min read

Properties5
StatusProposed
Tagsendosymbiosis, natural-sciences
SourceLIT-1596 — Genome sequence of the endocellular bacterial symbiont of aphids Buchnera sp. APS
ExtendsTHEORY-1103 — On Shigenobu and colleagues' genome of Buchnera sp. APS, the aphid symbiont keeps the genes for the amino acids its host cannot make and has lost almost all of those its host can, uses host-made glutamate and aspartate as precursors, and lacks phospholipid synthesis and nearly all its own transcriptional regulators, so that its metabolism interlocks with the host's and it presumably lives only inside the bacteriocyte, a state reached by gene loss from an E. coli-like ancestor
Bears onQUESTION-277 — When formerly autonomous partners come to depend on one another, which of mutual dependence, reproductive cohesion, the distribution of essential functions across genomes, the host's regulatory control and the alignment of selection does each route to dependence bring about, and which of them, alone or together, make the partnership a new evolutionary individual?

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Source

Shigenobu, Watanabe, Hattori, Sakaki & Ishikawa (2000), LIT-1596, read in full in NOTE-1236. The authors infer from gene content, and from earlier physiology, that the partners’ metabolisms interlock and that Buchnera presumably lives only inside the bacteriocyte.

Where the evidence stands

What the paper shows, and what it does not, is THEORY-1103, Active, which this entry extends: that entry is the reading, this one the thesis. The promote_when above is THEORY-1103’s condition before the twenty-second status review promoted it, carried here unchanged, because it asks what would make the thesis true and not what the paper says.

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