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Smith RW Palmer RM Houlihan DF 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(2):135-144
Protein synthesis in fish has been previously correlated with RNA content. The present study investigates whether protein
and RNA synthesis rates are similarly related. Protein and RNA synthesis rates were determined from 3H-phenylalanine and 3H-uridine incorporation, respectively, and expressed as % · day−1 and half-lives, respectively. Three fibroblast cell lines were used: BF-2, RTP, CHSE 214, which are derived from the bluegill,
rainbow trout and Chinook salmon, respectively. These cells contained similar RNA concentrations (∼175 μg RNA · mg−1 cell protein). Therefore differences in protein synthesis rates, BF-2 (31.3 ± 1.8)>RTP (25.1 ± 1.7)>CHSE 214 (17.6 ± 1.1),
were attributable to RNA translational efficiency. The most translationally efficient RNA (BF-2 cells), 1.8 mg protein synthesised · μg−1 RNA · day−1, corresponded to the lowest RNA half-life, 75.4 ± 6.4 h. Translationally efficient RNA was also energetically efficient with
BF-2 cells exploiting the least costly route of nucleotide supply (i.e. exogenous salvage) 3.5–6.0 times more than the least
translationally efficient RNA (CHSE 214 cells). These data suggest that differential nucleotide supply, between intracellular
synthesis and exogenous salvage, constitutes the area of pre-translational flexibility exploited to maintain RNA synthesis
as a fixed energetic cost component of protein synthesis.
Accepted: 12 November 1999 相似文献
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The nearly complete nuclear large subunit ribosomal RNA (LSU rRNA) gene in corals was amplified by primers designed from
polymerase chain reaction (PCR) strategies. The motif of the putative 3′-terminus of the LSU rRNA gene was sequenced and identified
from intergenic spacer (IGS) clones obtained by PCR using universal primers designed for corals. The 3′-end primer was constructed
in tandem with the universal 5′-end primer for the LSU rRNA gene. PCR fragments of 3500 bp were amplified for octocorals and
non-Acropora scleractinian corals. More than 80% of the Acropora LSU rRNA gene (3000 bp) was successfully amplified by modification of the 5′-end of the IGS primer. Analysis of the 5′-end
of LSU rDNA sequences, including the D1 and D2 divergent domains, indicates that the evolutionary rate of the LSU rDNA differs
among these taxonomic groups of corals. The genus Acropora showed the highest divergence pattern in the LSU rRNA gene, and the presence of a long branch of the Acropora clade from the other scleractinian corals in the phylogenetic tree indicates that the evolutionary rate of Acropora LSU rDNA might have accelerated after divergence from the common ancestor of scleractinian corals.
Received February 17, 2000; accepted June 12, 2000. 相似文献
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