Showing papers on "Mitochondrial biogenesis published in 1987"

Induction of an increase in mitochondrial matrix enzymes in muscle of iron-deficient rats.

Abstract: Young rats maintained on an iron-deficient diet developed severe anemia and had large decreases in the levels of the iron-containing flavoproteins and cytochromes of the mitochondrial respiratory chain in skeletal muscle. In contrast, the levels of a number of mitochondrial matrix marker enzymes, including citrate synthase, isocitrate dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, 3-ketoacid-CoA transferase, and aspartate aminotransferase, increased in red skeletal muscle but not in white muscle. Phosphocreatine concentration was decreased and inorganic phosphate concentration was increased in soleus muscle frozen in situ. We hypothesize that the increase in mitochondrial matrix enzymes reflects a stimulus to mitochondrial biogenesis in posture-maintaining and weight-bearing red muscle fibers in severely iron-deficient rats. It is our working hypothesis that this stimulus to mitochondrial biogenesis arises from mild activity of the red fibers and is due to the same perturbation in cellular homeostasis that is normally caused by vigorous exercise or hypoxia. In iron deficiency, the stimulus to mitochondrial biogenesis can induce an increase in only those enzymes not prevented from increasing by iron deficiency, resulting in formation of mitochondria of grossly abnormal composition.

Biogenesis of Mammalian Mitochondria

Abstract: Publisher Summary Mitochondrial biogenesis involves a series of independent but highly integrated events including the replication of mitochondrial DNA (mtDNA), transcription and translation of mtDNA, transcription and translation of nuclear genes coding for mitochondrial proteins, import of the latter proteins into mitochondria, and assembly of the individual polypeptides into functional protein complexes. There is potential for regulation at each of these steps. A great deal of what is known about mitochondrial biogenesis has come from investigations of lower eukaryotes. This has been promoted by the powerful tools of genetics. Application of genetic methods to mammalian cells is far more difficult, and the methods are much less developed. Despite this, a picture of the biogenesis of the mammalian mitochondrion is slowly emerging that is similar to that in lower eukaryotes in some respects but differs radically in others. This chapter describes the present state of knowledge of mammalian mitochondrial biogenesis, with focus on possible sites and modes of regulation.

DNA repair precedes replicative synthesis during early germination in maize.

Abstract: DNA synthesis was studied during germination by following the rate of incorporation of radioactive thymidine into high molecular weight DNA. A peak of DNA synthesis was observed between the 8th and the 12th hour, i.e. before the beginning of the semi-conservative replication of genomic DNA, accompanied by an increase in the DNA content of the embryo. By the use of nucleoid sedimentation and nick-translation it was shown that, during the first hours of germination, extensive repair occurs of the DNA single-strand breaks present in the dry embryo. As a result, the DNA of the 16-h-germinated embryo acquires the conformation typical of that of the root meristemic cells active in transcription and replication. In addition we have shown that cytoplasmic organelle (most probably mitochondrial) DNA synthesis is very active during the prereplicative state which confirms earlier microscopic data on mitochondrial biogenesis during early germination.

Polypeptide Subunits Encoded by Nuclear Genes are Essential Components of Eukaryotic Cytochrome C Oxidase

Abstract: Eukaryotic cytochrome c oxidase spans the inner mitochondrial membrane and is a complex protein composed of: 4 redox centers (Fea, Cua, and the Fea3-Cua3 binuclear center)1; cardiolipin2,3; and as many as 13 polypeptides4,5. During the past several years, Saccharomyces cerevisiae cytochrome c oxidase has been used extensively for studies of mitochondrial biogenesis and genetics6 while bovine heart cytochrome c oxidase has provided most of the structural and functional data for the enzyme7. Recent work on the isolation and sequencing of the polypeptides of both enzymes8-21 as well as the cloning and sequencing of their genes22-31 has provided the complete primary sequences of the polypeptides in the holoenzymes from both bovine heart and yeast. The three largest polypeptides (designated subunit s I, II, and III) in both enzymes are encoded on mitochondrial DNA. The remaining polypeptides (6 in yeast4 and 9–10 in bovine heart5) are encoded by nuclear genes.

Structure and Biogenesis of the Plant Mitochondrial Inner Membrane

Abstract: Growth and differentiation in plants depends upon the integrated metabolism of, and provision of energy by, both mitochondria and chloroplasts. While in recent years considerable progress has been made in our understanding of the factors which regulate chloroplast biogenesis and function, comparable studies on mitochondria have received far less attention (for a review see 1). This is surprising given the many developmental transitions throughout the plant life cycle that are associated with, or are dependent upon, marked changes in mitochondrial number, structure and metabolism. A priority is therefore to gain an understanding of the role of the mitochondrion in meeting the changing energy requirements of the cell, and hence in determining plant yield and viability. In addition to the elucidation of metabolic pathways, and determination of important regulatory or limiting steps, there is a need to understand the factors regulating mitochondrial biogenesis. This will involve an understanding of how genetic, developmental and environmental factors regulate biogenesis and how this, in turn, influences plant development.

Synthesis of the Nuclear DNA-Encoded Subunits of Higher Plant Cytochrome C Oxidase and F1ATPase

Abstract: Active biogenesis of mitochondria occurs in higher plant cells without accompanying cell division in response to changes in physiological and environmental conditions. For instance, it is well known that a marked increase in respiratory activity in storage organs during seed germination is brought about by active mitochondrial biogenesis. As another example, reports from our laboratory have demonstrated that mitochondrial biogenesis takes place in sweet potato root tissue when the tissue is sliced and incubated under moist conditions at room temperature, namely wounded, or is infected with pathogens(1,2). In the former case, mitochondrial biogenesis is programmed during ontogenesis of individual plant, whereas in the latter, it is induced in response to stresses. We are interested in the question how mitochondrial biogenesis is programmed and induced in non-dividing cells of higher plants. At the present status of our knowledge, however, it seems to be very hard to make an approach toward the molecular mechanisms of the programming and induction of mitochondrial biogenesis. We should have much information about the mechanism of mitochondrial biogenesis itself in higher plant cells before we shall try to study the molecular mechanisms of the programming and induction of mitochondrial biogenesis.

CYT-21: A nuclear gene encoding a mytochondrial ribosomal protein of Neurospora crassa

Abstract: The purpose of my work has been to set up a procedure to isolate specific nuclear genes that are involved in the mitochondrial biogenesis of Neurospora crassa; to study the function and expresslon of one such gene and to determine which nuclearmitochondrial interactlons are involved in the expression of this gene. ... Zie: Summary