CYTOCHROME OXIDASE AND ITS DERIVATIVES. I. CARBON MONOXIDE AND CYANIDE COMPOUNDS.
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Carbon↗
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SHIFT OF CYTOCHROME OXIDASE ALPHA-PEAK FROM 603-605 M-UPSILON TO 590 M-UPSILON BY HEAT DENATURATION.
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Candida↗
Isolation and molecular characterization of KlCOX14, a gene of Kluyveromyces lactis encoding a protein necessary for the assembly of the cytochrome oxidase complex.
The yeast Kluyveromyces lactis was mutagenized with ethyl methane sulphonate and mutants unable to grow on respiratory carbon sources were isolated. Functional complementation of one of these mutants led to the isolation of KlCOX14, a gene encoding a 64 amino acid protein which is the functional homologue of Saccharomyces cerevisiae Cox14p, a protein necessary for the assembly of the cytochrome oxidase holoenzyme (Glerum et al., 1995). The disruption of KlCOX14 resulted in the absence of the absorption bands relative to cytochromes a and a(3) and in the complete loss of respiratory activity. Klcox14 mutants display the typical phenotype of pet mutants and have a reduced growth rate. In addition, unlike the wild-type, Klcox14 mutants are able to grow by fermentation also in the presence of low glucose. The nucleotide sequence of KlCOX14 has been deposited in the EMBL databank with Accession No. AJ238801.
Alleles↗
Molecular evolution of tephritid fruit flies in the genus Bactrocera based on the cytochrome oxidase I gene.
Fruit flies of the genus Bactrocera (Diptera: Tephritidae) are one of the major economically important insects in Asia and Australia. Little attention has been given to analyses of molecular phylogenetic relationships among Bactrocera subgenera. By using mitochondrial cytochrome oxidase I gene (COI) sequences, the phylogenetic relationships among four subgenera, Asiadacus, Bactrocera, Hemigymnodacus, and Zeugodacus, were investigated. Nucleotide diversity within subgenera ranged from 11.7 to 12.4%, and the net divergence among subgenera ranged from 11.2 to 15.7%. Phylogenetic trees calculated from both maximum parsimony and neighbor-joining phylogenetic analysis methods were highly congruent in terms of tree topologies. Phylogenetic analysis of mitochondrial COI sequences suggests that tephritid fruit fly species, which attack cucurbit plants, that is, Asiadacus, Hemigymnodacus and Zeugodacus, were more closely related to each other than to fruit fly species of the subgenus Bactrocera, which attack plants of numerous families. Our data supports previous classification of Bactrocera based on morphological characters. However, the phylogenetic tree showed the polyphyletic of fruit flies in subgenus Zeugodacus. Possible causes of speciation among fruit flies species in this genus were also discussed.
Amino Acid Sequence↗
Depolarizing stimulation upregulates GA-binding protein in neurons: a transcription factor involved in the bigenomic expression of cytochrome oxidase subunits.
Neurons are unique in having dendrites that extend far away from their cell bodies. Mitochondria located in the dendrites can be separated from the nucleus for long distances. The mechanism of bigenomic coordination is of particular importance to cytochrome oxidase (CO), which has subunits that are encoded in both the nuclear and mitochondrial DNA. GA-binding protein (GABP) is a transcription factor that is required for the promoter activity of mitochondrial transcription factor A as well as several nuclear-encoded CO subunits. Thus, GABP may play a key role in coordinating the transcription of both mitochondrial and nuclear-encoded subunits of CO. The goal of the present study was to determine if GABP was expressed in neurons and whether and how it responded to increased neuronal activity. Using primary neuronal cultures, the beta-subunit of GABP was localized immunocytochemically to both the cytoplasm and the nucleus, whereas the alpha-subunit was expressed mainly in the nucleus. In KCl-treated cultures, immunoreactivity for both alpha- and beta-subunits was significantly increased in the nucleus compared with untreated sister cultures. The induction of GABP preceded that of CO gene expression from the two genomes, which, in turn, preceded that of CO activity. Thus, our data suggest that neuronal activity regulates subunit concentrations of GABP in the nucleus, and GABP may be a critical sensor of changes in neuronal activity. Our data are also consistent with the postulated role of GABP as a coordinator of both mitochondrial and nuclear transcription for subunits of CO in neurons.
Animals↗
Slow oscillations of cytochrome oxidase redox state and blood volume in unanesthetized cat and rabbit cortex. Interhemispheric synchrony.
The purpose of this study was to determine the frequency characteristics and the degree of interhemispheric synchrony of slow (< 0.5 Hz), spontaneous oscillations of the regional cortical cytochrome oxidase redox state (CYT) and blood volume (CBV) in unanesthetized animals. We implanted bilateral cortical windows and electrodes for polysomnography in 7 cats and 3 rabbits. The animals were atraumatically restrained during multiple 3-6 hour sessions for up to 8 weeks, and relative changes in the cortical CYT and CBV were monitored by dual wavelength reflectance spectrophotometry at 603 nm and 590 nm. Continuous oscillations of CYT and CBV, unrelated to pulse or respiration, were always observed in each animal. Frequency (FFT) analysis over time revealed a nonstationary distribution of frequencies below 0.4 Hz, with most of the spectral power being contained in the 0-0.25 Hz band during both waking and sleep. Although the time-frequency plots of the CYT and CBV signals were similar, an occasional dissociation between the CYT and CBV oscillations was found. Analysis of simultaneous bilateral cortical optical recordings revealed a significant and sustained interhemispheric cross-correlation over time between the CYT as well as the CBV oscillations during stable recordings as long as 60 min. We conclude that: 1) CYT and CBV levels normally oscillate at < 0.4 Hz in the unanesthetized cat and rabbit cortex; 2) these complex oscillations, whose frequencies are non-stationary over time, nevertheless show sustained interhemispheric synchrony between 50 mm2 homotopic cortical regions; and 3) these oscillations may in part represent fluctuations of the metabolic rate.
Animals↗
Cytochrome oxidase activity and mitochondrial gene expression in skeletal muscle of patients with chronic obstructive pulmonary disease.
Several recent studies have suggested that skeletal muscle bioenergetics are abnormal in patients with chronic obstructive pulmonary disease (COPD). This study investigates the activity of cytochrome oxidase (COX), the terminal enzyme in the mitochondrial electron transport chain, and the expression of two mitochondrial DNA genes related to COX (mRNA of subunit I of COX [COX-I] and the RNA component of the 12S ribosomal subunit [12S rRNA]), in quadriceps femoris muscle biopsies obtained from COPD patients with various degrees of arterial hypoxemia, and from healthy sedentary control subjects of similar age. The activity of COX was measured spectrophotometrically in fresh tissue at 37 degrees C with excess substrate. RNA transcripts were measured using reverse transcription and polymerase chain reaction. The measurements of mRNA COX-I and 12S rRNA were normalized to the mRNA of actin, which is a housekeeping gene not influenced by hypoxia. We found that, compared with control subjects, COPD patients with chronic respiratory failure (PaO2 < 60 mm Hg) showed increased COX activity (p < 0.05). Further, the activity of COX was inversely related to arterial PO2 value (Rho -0.59, p < 0.01). The COX-I mRNA content was not different between patients and control subjects but patients with chronic respiratory failure had higher levels of 12S rRNA (p < 0.05), which were again inversely related to PaO2 (Rho -0.49, p < 0.05). These results indicate that the activity of COX is increased in skeletal muscle of patients with COPD and chronic respiratory failure, and they suggest that this is likely regulated at the translational level by increasing the number of mitochondrial ribosomes.
DNA, Mitochondrial↗
[Postnatal development of barreloid neuropils in the ventrobasal complex of mouse thalamus: a histochemical study for cytochrome oxidase].
Postnatal development of barreloid neuropils was studied in the ventrobasal complex of mouse thalamus. A single barreloid neuropil which topographically represented a corresponding facial vibrissa on the contralateral side was demonstrated as a solid reaction mass with the method for cytochrome oxidase. This architectural unit was called a vibrissa compartment. On postnatal Day 0, the nuclear area of the ventrobasal complex showed higher activity for the enzyme than in regions around, but no barreloids were seen. Barreloid neuropils became detectable on postnatal Day 3 in the dorsomedial subnucleus of the ventrobasal complex and the septal delimitation of barreloids was established on postnatal Day 6. The arrangement of barreloids showed a distinct orderlines similar to that of facial vibrissae on a horizontal section. Barreloid neuropils contained synaptic glomeruli ensheathed with glial processes, in which dendritic processes and their excrescences of nerve cells received large terminal knobs in well-organized manner. On postnatal Day 10, immature glomerular forms were found in barreloid neuropils. The synaptic glomerulus of mature type, however, was not formed till postnatal Day 13. The number of synaptic junctions was examined in barreloid neuropils from postnatal Day 3 to 21. The result that the growth rate of synaptic junctions was the highest in a short period from postnatal Day 10 to 13 suggested rapid maturation of barreloid neuropils in this period. On postnatal Day 21, several types of synaptic contacts became remarkable in matured glomeruli. One of them, a filamentous type with association of clear synaptic vesicles at presynaptic sites was indicated. And non-synaptic junctional complex accompaning tubular structures beneath dense materials at dendritic sites was remarked between terminal knobs and dendritic processes. From results the following conclusions are remarked that at the level of mouse thalamus, septal delimitation of vibrissa compartments appeared on postnatal Day 3 and was established until postnatal Day 6. On the other hand, barreloid neuropils containing glomerular synaptic complexes became a maturing state on postnatal Day 13, that is, about one week later after architectural compartmentalization.
Animals↗
Mitochondrial DNA from a spider mite: isolation, restriction map and partial sequence of the cytochrome oxidase subunit I gene.
Mitochondrial (mt) DNA of the phytophagous mite Tetranychus urticae was purified and a restriction map was constructed. The 12.5 kb long genome is the shortest animal mtDNA known. A 564 bp clone comprising part of the gene for cytochrome oxidase subunit I was sequenced. As has been found in insects, the mitochondrial sequences of mites are extremely A+T rich (75% on average, 96.5% at the third codon position).
Animals↗
Cytochrome oxidase activity in the hypothalamus of SHR and normotensive rats before and after fasting.
The metabolic activity in the brains of adult spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY), and Wistar (W) rats was assessed before and after fasting using cytochrome oxidase (COX) histochemistry. Before fasting, metabolic activity in the paraventricular (PVH) and supraoptic (SON) nuclei of the hypothalamus in SHR was greater than in control rats. Fasting elicited a decrease in arterial pressure (AP) in SHR and WKY; in SHR the decrease in AP was accompanied by a decrease of metabolic activity in the PVH and SON. The findings of this study support the hypothesis that the PVH and SON are involved in the hypertension and in the increased levels of sympathetic nervous activity and vasopressin production known to occur in SHR. In addition, the PVH and possibly the SON may be involved in the suppression of sympathetic nervous system activity and the lowering of arterial pressure which are associated with fasting.
Animals↗
Identification of snails within the Bulinus africanus group from East Africa by multiplex SNaPshot trade mark analysis of single nucleotide polymorphisms within the cytochrome oxidase subunit I.
Identification of populations of Bulinus nasutus and B. globosus from East Africa is unreliable using characters of the shell. In this paper, a molecular method of identification is presented for each species based on DNA sequence variation within the mitochondrial cytochrome oxidase subunit I (COI) as detected by a novel multiplexed SNaPshotTM assay. In total, snails from 7 localities from coastal Kenya were typed using this assay and variation within shell morphology was compared to reference material from Zanzibar. Four locations were found to contain B. nasutus and 2 locations were found to contain B. globosus. A mixed population containing both B. nasutus and B. globosus was found at Kinango. Morphometric variation between samples was considerable and UPGMA cluster analysis failed to differentiate species. The multiplex SNaPshotTM assay is an important development for more precise methods of identification of B. africanus group snails. The assay could be further broadened for identification of other snail intermediate host species.
Animals↗
Control of respiration in sonicated cytochrome oxidase proteoliposomes by gated and ungated ionophores.
Respiration of cytochrome oxidase-containing sonicated proteoliposomes is partially stimulated by nigericin or by alamethicin. Valinomycin at low concentrations fully releases the nigericin-dependent respiration but inhibits the alamethicin-dependent respiration. Respiratory stimulation by the gated ionophore alamethicin must occur in the face of a continuing membrane potential; stimulation by nigericin is accompanied by an increase in the measured membrane potential. We conclude that delta pH rather than delta psi may be the main source of respiratory control in our type of proteoliposomes.
Alamethicin↗
Chromous ion reduction of mammalian cytochrome oxidase and some of its derivatives.
The reduction of cytochrome c oxidase by Cr2+, followed by means of stopped-flow spectrophotometry, exhibits two phases: the faster Cr2+-concentration-dependent reaction has an initial rate constant of 1.1 X 10(4)M-1-S-1, but reaches a rate limit at high concentration of reductant; the slower phase is concentration-independent with a rate of 0.3S-1. The activation energies of the fast and the slow processes are 35 and 71 kJ/mol respectively. The reduction kinetics of the mixed-valence CO complex and the cyanide-inhibited enzyme were compared with those of the fully oxidized forms: both the liganded species have a fast phase identical with that found in the oxidized oxidase. A comparison of the kinetic difference spectra obtained for the fast phase of reduction of oxidized oxidase with those obtained on reduction of the liganded species suggests that the rapid phase arises from the reduction ofhaem a, and the slow phase from the reduction of haem a3.
Chromium↗
ON CYTOCHROME OXIDASE AS THE TERMINAL OXIDASE OF DARK RESPIRATION OF NON-SULFUR PURPLE BACTERIA.
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Aniline Compounds↗
The mutability of low-affinity nerve growth factor receptor (p75NGFR) expression in the rat cuneate nucleus following perinatal injury and adult deafferentations: comparisons with cytochrome oxidase.
In normal adult rats, intense immunostaining for the 75 kDa low-affinity receptor for nerve growth factor and other neurotrophins (p75NGFR) is concentrated in the middle region of the cuneate nucleus (CN), distributed in a blotchy pattern similar to that of cytochrome oxidase (CO) activity. In the adult rats, partial dorsal rhizotomies (centered around the 7th and 8th cervical spinal segments) resulted in the complete disappearance of p75NGFR-like immunoreactivity within the ipsilateral CN, but did not affect the distribution of the CO blotches. Perinatal (postnatal day 1-8) damage to the ipsilateral forepaw and subsequent rearing to adulthood also resulted in significant disruption of the topographical expression of p75NGFR-like immunoreactivity within the CN, as well as--as previously reported--disruption of the CO blotches. Although the patterns of staining in intact adult rats are similar for CO staining and for p75NGFR-like immunoreactivity within the CN, the CO staining appears to be primarily associated with postsynaptic cells, while the p75NGFR-like immunostaining appears to be associated with primary afferent terminals.
Afferent Pathways↗
Expression of cytochrome oxidase in hair cells of the teleost utricle.
Ultrastructural variation in some cytoplasmic organelles and synaptic structures is one characteristic distinguishing the types of hair cells in the teleost ear. In this study, we explored differences in mitochondria by analyzing mitochondrial reactivity for cytochrome oxidase (COX) in hair cells of the teleost utricle. The reactivity for COX within mitochondria in the subcuticular compartment directly beneath the cuticular plate differentiated among hair cells in utricles of three teleost species, Carassius auratus, Pantodon buchholzi, and Astronotus ocellatus. Mitochondria in the subcuticular region of hair cells in the striola reacted intensely. Within juxtastriola and extrastriolar hair cells near the striola, mitochondria reacted at a lowered intensity than in striolar hair cells. Subcuticular mitochondria of extrastriolar hair cells located distant from the striola reacted negligibly. The reactivity of mitochondria in other cytoplasmic compartments did not provide similar evidence for distinguishing among teleost hair cells. Mitochondria within intraepithelial branches of the eighth nerve terminals in the different utricular regions reacted to COX histochemistry commensurate with their respective presynaptic hair cells. Branches of sensory afferent neurons innervating striolar hair cells displayed a dense COX reaction. Sensory afferents innervating the extrastriolar hair cells did not display many mitochondria at synapses nor, when present, was the staining as dense. The presynaptic side of the hair cell-afferent nerve synapse usually, but not always, contained reactive mitochondria. The presynaptic side of the efferent nerve-hair cell synapse did not necessarily contain mitochondria. Mitochondria filling the cytoplasm in a type of juxtamacula cell revealed uniformly dense COX reactivity.
Animals↗
Injury-resistant retinal ganglion cells that are rich in cytochrome oxidase.
Previous studies have demonstrated that the vast majority of retinal ganglion cells (RGCs) die one month after optic nerve transection. However, a small percentage do not degenerate. The present study examined one aspect of the chemical nature of these surviving RGCs using cytochrome oxidase (CO) as a neuronal marker in whole-mounted retinae. In the normal retina, 4.3% of the total population of RGCs show high CO activity. One month after optic nerve transection, 37% of the CO-positive RGCs counted in the control retinae survive and, because they stain with CO, must be metabolically active. Previous studies have shown that only up to 10% of the total RGC population survive optic nerve transection. The implication of our results is that the CO-positive RGCs, as a subpopulation, are more resistant to injury than the general population of RGCs.
Animals↗
The Zea mays mitochondrial gene coding cytochrome oxidase subunit II has an intervening sequence and does not contain TGA codons.
Cross hybridization between maize mitochondrial DNA fragments and a specific yeast mitochondrial DNA probe from the oxi 1 gene has been used to identify and isolate the maize mitochondrial gene coding cytochrome oxidase subunit II, mox 1. The DNA sequence reveals two coding regions separated from each other by a single centrally located intervening sequence. Hybridization of mox 1 DNA probes to mitochondrial RNA from plants shows that te gene is transcribed and indicates that several transcripts are spliced. TGA codons, which code Trp in the mitochondria of all species examined to date, do not occur in this gene. However, alignment of the mox 1 gene sequence with the amino acid sequences of subunit II from other organisms strongly suggests that codon CGG (normally Arg) codes for Trp in maize mitochondria, in addition to the standard Trp codon TGG.
Base Sequence↗