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PubMed1990

Increase in cytochrome oxidase capacity of BAT and other tissues in cold-acclimated gerbils.

To determine the effects of cold acclimation on the oxidative capacity of different tissues and their possible role in nonshivering thermogenesis (NST) in a desert rodent, the gerbil (Gerbillus campestris), measurements of cytochrome oxidase activity (COX) were performed on homogenates of liver, brown adipose tissue (BAT), and subsarcolemmal (SS) and intermyofibrillar (IMF) fractions of skeletal muscle. Total organ mass was also measured. Gerbils were maintained either at thermoneutrality (TN) or cold [4 degrees C, ambient temperature (Ta)] for 4 (CA4) or 8 (CA8) wk. A comparative study was made with mice (Mus musculus). Total and relative masses of BAT increased significantly in both gerbils and mice during cold acclimation, whereas muscle mass decreased in CA4 gerbils. Specific and total COX (TCOX) increased in the three tissues. A considerable increase (+170%, P less than 0.05) of TCOX and protein content in liver of CA4 gerbils compared with controls was observed, whereas no significant changes occurred in liver of CA4 mice. In muscle, an increase of TCOX in SS and a reduction in IMF cell compartments were noted. The increase in BAT oxidative capacity in CA4 gerbils represented only a small portion of that in liver (36%) and in SS fraction of muscle (41%) at the same stage of acclimation. The ability of the three tissues to contribute to components of thermogenesis in vivo was evaluated. The sum of oxidative capacity of the three tissues was largely above the peak metabolic rate (PMR), whereas that of muscle exceeded maximum shivering thermogenesis, which developed both in TN and CA4 gerbils.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1992

Coordination of ATP production and consumption in brain: parallel regulation of cytochrome oxidase and Na+, K(+)-ATPase.

Previous studies have shown that most neuronal ATP is produced by oxidative metabolism, and consumed by Na+,K(+)-ATPase. We hypothesized that the distribution of Na+,K(+)-ATPase in brain would correlate with that of the energy-producing enzyme, cytochrome oxidase (CO). We localized these enzymes in monkey hippocampus and striate cortex by histochemistry and immunohistochemistry. Their distributions were generally similar, although some differences were observed. We also studied regulation of enzyme levels, using monocular impulse blockage with tetrodotoxin (TTX) to alter neuronal activity in the visual system. Parallel changes in CO and Na+,K(+)-ATPase activity were induced in striate cortex. These results provide further evidence that neuronal energy demands regulate CO levels and distribution.

Adenosine Triphosphate↗
PubMed1996

Do nitric oxide synthase, NMDA receptor subunit R1 and cytochrome oxidase co-localize in the rat central nervous system?

The activation of nitric oxide synthase (NOS) has been linked to excitatory input via NMDA receptors. We hypothesized that NOS-positive neurons that have NMDA receptors on their surface would have high levels of cytochrome oxidase (C.O.) as energy generator for membrane repolarization. In order to compare the distribution of these markers on the same section, we reacted rat brain sections for C.O. histochemistry followed by NOS immunogold silver staining (IGSS). Adjacent sections were reacted for NOS IGSS followed by indirect immunoperoxidase for NMDA receptor subunit R1 (NMDAR1). We found that the staining pattern varied among regions but were consistent within each region examined. There are three types of NOS immunoreactive (NOS-ir) cells: (1) NOS-ir neurons that had moderate to high levels of both NMDAR1 and C.O. staining, such as the pontine reticular nuclei, motor and mesencephalic nuclei of the trigeminal nerve, and some motor neurons in the spinal cord. (2) NOS-ir neurons that were immunoreactive for NMDAR1 (NMDAR1-ir) but had low levels of C.O. activity in thei- somata. Their dendrites, however, were both NMDAR1-ir and rich in C.O. Examples of this type include neurons in the caudate and putamen, and periglomerular cells in the olfactory bulb. (3) We also found that some NOS-ir neurons were not NMDAR1-ir and had low C.O. activity. In addition to postsynaptic neurons, C.O. and NOS levels were both high in the inner segments of retinal photoreceptor cells where energy-demanding active ion transport maintains the dark current and where NO presumably activates guanylate cyclase for the production of cGMP, which keeps the Na+ channels open in the dark. Our findings suggest that NMDA receptors are available for the majority of NOS-ir neurons, which comprise a heterogenous population with varying energy demands.

Animals↗
PubMed1991

Studies on plantacyanin. IV. Reconstitution with Cu-thionein, oxidation by cytochrome oxidase and autooxidation in the presence of cardiolipin.

Cu-thionein isolated from cucumber roots was used for reconstitution of plantacyanin from cucumber. The rate of the copper transfer from Cu-thionein to apoplantacyanin was found to depend on pH, ionic strength and concentrations of the proteins. The rate of reconstitution with Cu-thionein was 10-times higher than with copper ions. No intermediate was observed during reconstitution with Cu-thionein. The incubation of oxidized holoplantacyanin with Cu-thionein or apothionein brings about the reduction of plantacyanin copper. This process, however, was found to be slow as compared to the rate of copper transfer from Cu-thionein to apoplantacyanin. Cytochrome oxidase from heart mitochondria was detected to possess some plantacyanin oxidase activity with the turnover number 5 min-1. The activity of the enzyme towards plantacyanin as well as with cytochrome c as a substrate was established to be lipid and ionic strength-dependent, and it was inhibited by CN- and N3-. Lineweaver-Burk plots show that the inhibitory effect of ionic strength on plantacyanin oxidase activity is connected with changes of Michaelis constant rather than of the maximal rate. Plantacyanin which is known to be very resistant towards many cationic, anionic and nonionic detergents, becomes, as well as cytochrome c, autooxidable in the presence of cardiolipin.

Animals↗
PubMed1985

Identification and isolation of the cytochrome oxidase subunit II gene in mitochondria of the yeast Hansenula saturnus.

Mitochondrial DNA from the petite negative yeast Hansenula saturnus has been isolated and sized by digestion with restriction enzymes. The size of the mitochondrial genome is approximately 47 kb. The gene for subunit II of cytochrome oxidase was localized in the genome by Southern blotting using a [32P]-labeled probe containing the subunit II gene of the yeast Saccharomyces cerevisiae. The probe hybridized to a 1.7 kb HindIII-BamHI fragment under stringent conditions (65 degrees C), indicating a high degree of homology between the S. cerevisiae and H. saturnus mitochondrial DNA fragments. The 1.7 kb fragment from H. saturnus was cloned into pBR322 and physically mapped. The map was used to obtain the nucleotide sequence of the subunit II gene (Lawson and Deters presented in the accompanying paper).

DNA Restriction Enzymes↗
PubMed1989

DNA sequence analysis of the 24.5 kilobase pair cytochrome oxidase subunit I mitochondrial gene from Podospora anserina: a gene with sixteen introns.

The DNA sequence of a 26.7 Kilobase pair (10(3) base pairs = 1 Kb) region of the mitochondrial genomes of races s and A from Podospora anserina was determined. Within this region, the 24.5 Kb cytochrome oxidase subunit I gene was located and its exon sequences determined by computer analysis comparisons with other fungal genes. The Podospora COI gene was interrupted by two group II introns (one in race s) and fourteen group I introns ranging in size from about 2.2 Kb to 404 bp. Earlier studies on secondary structure analysis, as well as comparison of their open reading frames (ORFs), showed that the two group II introns were closely related. The fourteen group I introns were representatives of three subgroupings (IB, C and a new category, subgroup ID). Two of these group I introns were separated by just a single exon codon. The analysis of all these introns is discussed in comparison with other fungal introns as well as with the known Podospora anserina introns.

Amino Acid Sequence↗
PubMedDate not supplied

Relationship between orientation domains, cytochrome oxidase stripes, and intrinsic horizontal connections in squirrel monkey area V2.

Area V2, the main target of primary visual cortex projections, is characterized by a striking functional and connectional compartmentalization. Many aspects of this organization are correlated to three sets of stripes (thick, thin, and pale) revealed by cytochrome oxidase (CO) staining. Several questions related to the physiological properties of these compartments, their intrinsic connections, and points of similarity with area V1 modules are still unresolved. We have addressed some of these questions by combining the techniques of optical imaging of intrinsic signals, tract tracing, and CO histochemistry in the same patches of areas V1 and V2 of the squirrel monkey. The following observations were made. Orientation domains: in area V1 these are organized in narrow bands, while in area V2 they form patches. In area V2, domain width and distance between domains are approximately double that found in area V1. Orientation and CO stripe organization: orientation tuning was organized so that highly selective regions were centered on thick CO stripes while regions of broad orientation selectivity were centered on thin CO stripes. However, the orientation domains appeared to ignore borders between thick and pale stripes. Intrinsic connections: injections of the sensitive tracer biocytin into area V2 labeled a dense network of horizontally projecting fibers that were organized in columnar patches. Patches were small (mean width, 211 microns; mean length, 342 microns) and the labeling pattern extended over 4-5 mm. Axonal patches and CO stripes: Axonal patches found were in all three stripe compartments. However, injections that straddled the borders of thick/pale stripe compartments produced axonal projections that tended to cluster around border regions. Axonal patches and orientation domains: V2 injections produced labeling in V1 that appeared to be organized in narrow bands, reminiscent of orientation domain distribution in V1. Within area V2, axonal patches targeted a wide range of orientation domains, but appeared to avoid domains having orthogonal orientation preference to that found at the injection site. To conclude, our results show, on the one hand, a measure of functional specificity for the CO stripes and the intrinsic connections. On the other hand, they indicate additional substructures within area V2, whose precise relationship to the known compartmental organization remains to be clarified.

Animals↗
PubMed1980

The genetic code in bovine mitochondria: sequence of genes for the cytochrome oxidase subunit II and two tRNAs.

Bovine-heart mitochondrial DNA from a single animal was isolated and fragments representative of the entire genome cloned into multicopy plasmid vectors to facilitate determination of its complete nucleotide sequence. We present here the sequence of the region covering the gene for cytochrome oxidase subunit II. Comparison of this sequence with the amino acid sequence of the homologous beef-heart protein has enabled the determination of most of the bovine mitochondrial genetic code. The code differs from the "universal" genetic code in that UGA codes for tryptophan and not termination, and AUA codes for methionine and not isoleucine. The only codon family not represented is the AGA/AGG pair normally used for arginine; evidence from other genes suggests that these code for termination in bovine mitochondria. The sequence presented also includes the adjacent tRNAAsp and tRNALys genes. The tRNAAsp gene is separated by one nucleotide from the 5' end of the COII gene and only three bases separate the 3' end of this gene and the adjacent tRNALys gene. This highly compact gene organisation is very similar to that found in the corresponding region of the human mitochondrial genome and the gene arrangement is identical. The structure of the respective bovine and human tRNAs vary primarily the "D-" and "T psi C-loops".

Animals↗
PubMed1999

Papilio phylogeny based on mitochondrial cytochrome oxidase I and II genes.

Butterflies of the genus Papilio have served as the basis for numerous studies in insect physiology, genetics, and ecology. However, phylogenetic work on relationships among major lineages in the genus has been limited and inconclusive. We have sequenced 2.3 kb of DNA from the mitochondrial cytochrome oxidase I and II genes (COI and COII) for 23 Papilio taxa and two outgroups, Pachliopta neptunus and Eurytides marcellus, in order to assess the potential of these genes for use in Papilio phylogenetics and to examine patterns of gene evolution across a broad taxonomic range. Nucleotide and amino acid variation is distributed heterogeneously, both within and between genes. Structural features of the proteins are not always reliable predictors of variation. In a combined analysis, these sequences support a nearly fully resolved topology within subgenera and species groups, though higher level relationships among species groups require additional study. The most noteworthy findings are that neither Papilio alexanor nor P. xuthus belongs in the machaon group and that the subgenus Pterourus is paraphyletic with respect to the subgenus Pyrrhosticta. We leave relationships among members of the phorcas species group as a trichotomy. These two protein coding genes, particularly COI, show excellent performance in resolving relationships at the level of species and species groups among Papilionidae. We strongly endorse a similar approach for future studies aimed at these levels.

Animals↗
PubMed1989

The cytochrome oxidases of Bacillus subtilis: mapping of a gene affecting cytochrome aa3 and its replacement by cytochrome o in a mutant strain.

A mutant of Bacillus subtilis has been isolated that fails to grow on succinate as the source of carbon, yet grows on glucose. Intact cells of the mutant and cytoplasmic membranes derived therefrom lack cytochromes a and a3 but contain a cytochrome o-like pigment, which forms a photodissociable compound with CO and is reactive with oxygen. The mutation in the genome has been located and lies at about 130 degrees on the chromosomal map between the metC and pyrD loci. The designation cox is suggested for this gene.

Bacillus subtilis↗
PubMed1984

Comparative Cytochrome Oxidase and Superoxide Dismutase Analyses on Strains of Azotobacter vinelandii and Other Related Free-Living Nitrogen-Fixing Bacteria.

Quantitative N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) oxidase and superoxide dismutase (SOD) analyses were performed on representative organisms of the family Azotobacteraceae. Azotobacter vinelandii, Azotobacter chroococcum, Azotobacter paspali, and Derxia gummosa exhibited high quantitative TMPD oxidase activities, and their extracts possessed very active and electrophoretically homogeneous (single gel band) Fe-type SODs. Azomonas macrocytogenes extracts had similar single Fe-type SODs, and their cells exhibited no TMPD-dependent cytochrome oxidase activity. Nitrogen-fixing cells of Beijerinckia indica, Beijerinckia derxii, and Beijerinckia mobilis exhibited minimal TMPD oxidation capabilities (rates equivalent to the TMPD autooxidation reaction), and these extracts also possessed very active SODs but only of the Mn metallotype.

Journal Article↗
PubMed1992

Differential expression of cytochrome oxidase (COX) genes in different regions of monkey brain.

A frontal pole cDNA library from monkey (Macaca mulatta) brain was screened to identify mRNAs that are expressed more in frontal pole as compared to primary visual cortex. Three cDNA clones, whose greater expression was confirmed by Northern blot analysis, were identified as cytochrome oxidase (COX) subunits I, II, and III (COX I, II, and III). Each clone showed higher levels of mRNA in the frontal pole, dorsal lateral prefrontal cortex, and hippocampus than in the primary visual or somatosensory cortices. COX histochemistry of prefrontal, visual, and somatosensory cortical regions demonstrated heterogeneous distributions, with highest activity in dendrite-rich neuropil of the cortex. A laminar distribution of COX mRNA expression also was demonstrated with in situ hybridization. mRNA was detected in cell bodies and in apical dendrites. These results indicate region specific differences in the distribution of COX activity and in the corresponding mRNA for three of its subunits within the monkey brain. Such differences may be related to differences in the distribution of neuropil as compared with cell bodies among the brain regions studied, and may be relevant to selective vulnerability in Alzheimer's disease.

Animals↗
PubMed1983

The oxygen binding site of cytochrome oxidase. Structural predictions on subunit I from amino acid sequences.

Analyses of heme-attached amino acid sequences in known hemoprotein superfamilies provide a basis for prediction of such sequences in hemoproteins of unknown three-dimensional structure. Among 11 histidine residues conserved in subunit I of 3 mammalian and 2 fungal cytochrome oxidases the sequence around His-233 (human) is the most conserved and shows remarkable similarity to the sequence of the oxygen binding site in globins. Furthermore, the gene coding for subunit I in Saccharomyces cerevisiae and the gene for leghemoglobin in soybean are both split by introns right after these similar histidine sequences. The predicted distal histidine sequence of subunit I provides for heme a3 and Cua3 binding and has an extraordinarily high content of aromatic residues. These aromatic groups may serve as a molecular electron capacitor. Transmembrane sequences and electron transfer sequences are proposed.

Amino Acid Sequence↗
PubMed2004

Cytochrome oxidase I gene sequence of Hypoderma sinense infecting yaks in the Qinghai-Tibet high plateau of China.

The previous scanning electron microscopy study of the Hypoderma species suggested that Hypoderma sinense Pleske (H. sinense) was different from Hypoderma bovis (H. bovis) and Hypoderma lineatum (H. lineatum). In this study, the mitochondrial cytochrome oxidase I (COI) gene sequence of H. sinense was compared with those of the other two species. The H. sinense sequence showed only 88.3% homology to H. bovis and 88.5% to H. lineatum. The results of the sequencing analysis confirm that H. sinense is a different species from H. bovis and H. lineatum.

Animals↗
PubMedDate not supplied

Cytochrome-oxidase blobs and intrinsic horizontal connections of layer 2/3 pyramidal neurons in primate V1.

Pyramidal neurons in superficial layers of cerebral cortex have extensive horizontal axons that provide a substrate for lateral interactions across cortical columns. These connections are believed to link functionally similar regions, as suggested by the observation that cytochrome-oxidase blobs in the monkey primary visual cortex (V1) are preferentially connected to blobs and interblobs to interblobs. To better understand the precise relationship between horizontal connections and blobs, we intracellularly labeled 20 layer 2/3 pyramidal neurons in tangential living brain slices from V1 of macaque monkeys. The locations of each cell body and the cell's synaptic boutons relative to blobs were quantitatively analyzed. We found evidence for two cell types located at characteristic distances from blob centers: (1) neurons lacking long-distance, clustered axons (somata 130-200 microm from blob centers) and (2) cells with clustered, long-distance axon collaterals (somata < 130 microm or >200 microm from blob centers). For all cells, synaptic boutons close to the cell body were located at similar distances from blob centers as the cell body. The majority of boutons from cells lacking distal axon clusters were close to their cell bodies. Cells located more than 200 microm from blob centers were in interblobs and had long-distance clustered axon collaterals selectively targeting distant interblob regions. Cells located less than 130 microm from blob centers were found within both blobs and interblobs, but many were close to traditionally defined borders. The distant synaptic boutons from these cells were generally located relatively near to blob centers, but the neurons closest to blob centers had synaptic boutons closer to blob centers than those farther away. There was not a sharp transition that would suggest specificity for blobs and interblobs as discrete, binary entities. Instead they appear to be extremes along a continuum. These observations have important implications for the function of lateral interactions within V1.

Animals↗
PubMed2001

Cytochrome oxidase activity in the olfactory system of staggerer mutant mice.

The staggerer mutation is characterized by the disruption of a single recessive gene encoding for the nuclear hormone receptor RORalpha. In addition to the well-studied gene expression in the cerebellum causing massive primary Purkinje cell loss, the RORalpha gene is also expressed in the thalamus and the olfactory bulb. A quantitative histochemical study of cytochrome oxidase activity was performed in staggerer mutants and their respective controls in order to determine whether olfactory bulb neuropathology leads to neuronal metabolic alterations in olfactory and related limbic regions. In the staggerer olfactory bulb, the core and the shell of the glomeruli had lower levels of cytochrome activity, whereas higher levels were found in the external plexiform and granular layers. Other olfactory and limbic regions were unchanged, except for a higher level in the accessory olfactory bulb and a lower level in the most ventral part of the medial orbital cortex. These results are discussed with regard to the olfactory deficits and changes in social interactions previously observed in this mutant.

Animals↗