ABSTRACT
A cDNA encoding cytochrome c oxidase (COX) subunit VIa liver isoform (COX6aL) was isolated from a Mus musculus library and sequenced. The protein translated from the nucleotide sequence contains a presequence and is 91% identical to the human cognate sequence over the processed polypeptide region. Northern analysis shows the expression of COX6aL is developmentally regulated in heart, being about equally transcribed with the heart isoform (COX6aH) in 18-day embryos but consisting of less than 25% in adult heart.
Subject(s)
Electron Transport Complex IV/genetics , Liver/enzymology , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , DNA, Complementary , Electron Transport Complex IV/chemistry , Humans , Mice , Molecular Sequence Data , Sequence Homology, Amino AcidABSTRACT
It had not previously been known whether synthesis of nuclear-encoded mitochondrial subunits occurs in pre-implantation embryos. We have used cytoplasmic injections of antisense RNA transcribed in vitro to study this question. Capped, in vitro transcribed RNA antisense to either cytochrome c oxidase subunit IV or VIIc injected into each cell at the two-cell stage markedly inhibited synthesis of adenine nucleotide by the 8- to 16-cell stage, whereas injection of the cognate sense RNAs gave levels similar to those previously published for normal embryos. These results strongly suggest that translation of nuclear-encoded mRNAs for mitochondrial subunits is required during pre-implantation development. It was of additional interest that, not only was ATP decreased, but ADP and AMP as well, with the effect that the charge ratio remained constant. The results also suggest, therefore, that the mechanism by which cells normally regulate their charge ratio, though to be with adenylate deaminase, is already in place.
Subject(s)
Blastocyst/metabolism , Cell Nucleus/metabolism , Electron Transport Complex IV/antagonists & inhibitors , Electron Transport Complex IV/biosynthesis , RNA, Antisense/pharmacology , Adenosine Diphosphate/metabolism , Adenosine Monophosphate/metabolism , Adenosine Triphosphate/metabolism , Animals , Blastocyst/enzymology , Cell Nucleus/drug effects , Crosses, Genetic , Gene Expression , Macromolecular Substances , Mice , Mice, Inbred C57BL , Mice, Inbred Strains , Transcription, GeneticABSTRACT
Users need to know if the outlook information in the Occupational Outlook Handbook proves right. This evaluation shows that most of the 1980-90 projections were on target.
