@entity308 of the production and consumption of cellular energy appears to be a prerequisite for the survival of prolonged bouts of @entity519 . A correlation exists between the degree of @entity308 under @entity519 and the duration of @entity519 tolerance. In the case of brine shrimp ( @entity19928 ) embryos, @entity26 deprivation induces a reversible quiescent state that can be tolerated for several years with substantial survivorship. A global arrest of cytoplasmic translation accompanies the transition into @entity519 , and rates of protein synthesis in mitochondria from these embryos appears to be markedly reduced in response to @entity519 . Previous evidence suggests that the acute acidification of intracellular pH (pHi) by over 1.0 unit during the transition into @entity519 contributes to the @entity308 of biosynthesis, but message limitation does not appear to play a role in the down-regulation in either cellular compartment. The ontogenetic increase in mRNA levels for a mitochondrial-encoded subunit of cytochrome c oxidase (COX I) and for nuclear-encoded actin is blocked by @entity519 and @entity520 (artificial quiescence imposed by intracellular acidification under aerobic conditions). Further, the levels of COX I and actin mRNA do not decline appreciably during 6 h bouts of quiescence, even though protein synthesis is acutely arrested across this same period. Thus, the constancy of mRNA levels during quiescence indicates that reduced protein synthesis is not caused by message limitation but, instead, is probably controlled at the translational level. This apparent stabilization of mRNA under @entity519 is mirrored in an extension of protein half-life. The ubiquitin-dependent pathway for protein degradation is depressed under @entity519 and @entity520 , as judged by the acute drop in levels of ubiquitin-conjugated proteins. Mitochondrial protein synthesis is responsive to both acidification of pHi and removal of @entity26 per se. Matrix pH declines in parallel with pHi, and evidence from experiments with @entity6199 indicates that mitochondrial protein synthesis is depressed directly by acidification of matrix pH. The @entity26 dependency of organellar protein synthesis is not explained by blockage of the electron transport chain or by the increased redox state. Rather, this @entity3789 - and @entity11382 -insensitive, but @entity519 -sensitive, inhibitory signature for the arrest of protein synthesis suggests the presence of a molecular @entity26 sensor within the mitochondrion.

Quiescence in @entity19928 embryos: reversible arrest of metabolism and gene expression at low XXXX levels.

@entity308 :: ('MESH:D003866', 'Disease') :: ['Depression', 'depression', 'metabolic depression'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen'] @entity6199 :: ('MESH:D009550', 'Chemical') :: ['nigericin'] @entity520 :: ('MESH:D000138', 'Disease') :: ['aerobic acidosis'] @entity19928 :: ('6661', 'Species') :: ['Artemia franciscana'] @entity519 :: ('MESH:D000860', 'Disease') :: ['anoxia', 'hypoxia'] @entity3789 :: ('CHEBI:17514', 'Chemical') :: ['cyanide'] @entity11382 :: ('MESH:C032456', 'Chemical') :: ['antimycin']
@entity26 :: (MESH:D010100,Chemical) :: ['oxygen']
