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PubMed2002

Postnatal expression of neurotransmitters, receptors, and cytochrome oxidase in the rat pre-Bötzinger complex.

The pre-Bötzinger complex (PBC) is postulated as the center of respiratory rhythmogenesis. Previously, we found a reduction or plateau of cytochrome oxidase (CO) activity in the PBC and other respiratory nuclei at postnatal days 3-4, despite a general increase of CO with age, suggesting a period of synaptic readjustment. The present study examined the expression of CO and a number of neurochemicals in the PBC at closer time intervals. At postnatal days 3-4 and, more prominently, at postnatal day 12, expression of CO, glutamate, and N-methyl-D-aspartate receptor subunit 1 was reduced, whereas expression of GABA, GABA(B) receptor, glycine receptor, and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor subunit 2 was increased. These findings are consistent with our hypothesis that decreased CO activity is associated with an increase in inhibitory drive (mediated by GABA and glycine, their receptors, and possibly blockage of Ca(2+) entry by glutamate receptor subunit 2) and a decrease in excitatory drive (mediated by glutamate and its receptors). Our findings point to two critical periods during postnatal development of the rat when their respiratory system may be more vulnerable to respiratory insults.

Animals↗
PubMed1999

Morphology of pyramidal neurones in cytochrome oxidase modules of the S-I bill representation of the platypus.

The primary somatosensory cortex of the platypus (Ornithorhynchus anatinus) is characterized by a distinct array of functionally specific cytochrome oxidase (CO) modules, forming alternate CO-rich and CO-poor bands. In the current study, we undertook to establish whether the cellular morphology of layer V pyramidal neurones reflects this modular organization. To this end, we injected neurones with Lucifer Yellow in 250 microm thick, flat-mounted cortical slices and processed the tissue to reveal a light-stable reaction product. By aligning blood vessels in serial sections in which we injected individual neurones with sections processed for CO, we were able to establish the exact location of injected cells with respect to the pattern of CO bands. Pyramidal neurones in the CO-poor bands (which are responsive to both mechano- and electroreceptive stimuli) had basal dendritic fields that were larger than those in the CO-rich bands. The large basal dendritic fields of layer V pyramidal neurones in the CO-poor bands may allow for integration of a greater number of more diverse inputs, thus allowing for averaging of stimuli to improve the signal-to-noise ratio or enhance spatial discrimination of peripheral stimuli. In some instances, neurones located within approximately 100 microm of the boundaries of the CO bands had dendritic fields that appeared to conform to the CO bands, the dendrites preferentially arborizing within a single band and avoiding the neighbouring band. However, the bias was not absolute, as we observed many examples of cells with dendrites that crossed the boundary between bands. Furthermore, many cells had dendrites that showed distinct dendritic bias that bore no obvious relationship to the CO boundaries.

Animals↗
PubMedDate not supplied

[Membrane control of the photodeblocking reaction of cytochrome oxidase in the mitochondrial electron transport chain].

Hyperosmotic shrinkage and hypoosmotic swelling of the internal mitochondrial membrane decrease considerably the efficiency of the reaction of the cyanide photodissociation from the cytochrome oxidase. The osmotic effect increases after the reduction of the membrane potential by a protonophore uncoupler. This suggests that the local photochemical reaction is subject to membrane control.

Animals↗
PubMed1997

No mitochondrial cytochrome oxidase (COX) gene mutations in 18 cases of COX deficiency.

Cytochrome c oxidase (COX) deficiency causes a variety of neuromuscular and non-neuromuscular disorders in childhood and adulthood and can theoretically undergo either a nuclear or a mitochondrial (mt) mode of inheritance, making genetic counseling in COX deficiency particularly hazardous. In an attempt to determine the respective roles of mtDNA and nuclear DNA mutations in COX deficiency, we sequenced the three mitochondrially encoded COX subunits (COXI-III) in a series of 18 patients with isolated COX deficiency, especially as COXI-III code for the catalytic site of the enzyme. We failed to detect any deleterious mutations in this series. Moreover, no mtDNA deletion was observed and sequencing of the flanking tRNA genes involved in the maturation of the COX transcripts failed to detect deleterious mutations as well. The present study supports the view that the disease-causing mutations do not lie in the mt genome but, rather, in the nuclear genes encoding either the COX subunits or the proteins involved in assembly of the complex and suggests a recurrent risk of 25% rather than other modes of inheritance in COX deficiencies.

Cell Nucleus↗
PubMed1991

Age effects on cytochrome oxidase activities during denervation and recovery of three muscle fiber types.

The rat nasolabialis muscle is comprised of a mosaic of red, white, and intermediate muscle fiber types. Using computerized microdensitometry, cytochrome oxidase (COX) activity was quantitatively analyzed in each fiber type throughout the period of denervation and recovery in young adult (3-month) and middle-aged (15-month) male Sprague-Dawley rats. In animals of both age groups, the nasolabialis muscle on one side of the head was denervated by crushing the facial nerve. At specific days post crush (dpc) ranging from 2 days-2 months, animals were sacrificed and thick sections of normal and denervated muscles were incubated to demonstrate the activity of COX, a mitochondrial enzyme, which differentiates between the three fiber types. Enzyme activities in individual fibers were microdensitometrically analyzed using a digitizing image analyzer. Although a denervation-induced decreased followed by eventual recovery occurred in all fibers of each type, age-related differences were evident. For all types, younger fibers consistently showed decreased COX activity sooner than their older counterparts, and older fibers of all types consistently showed a greater decreased COX activity than the younger fibers. Denervation-induced de-differentiation of muscle fibers led to a more homogeneous population of fiber types in both age groups. Following recovery of function, the magnitude of the fiber enzyme activity change differed according to fiber type and to age, and was consistently smaller in older animals. The normal mosaic pattern of fiber type distribution and normal COX levels were restored 2 months after nerve lesion in both age groups.

Aging↗
PubMed2004

Cytochrome oxidase activity in the preoptic area correlates with differences in sexual behavior of intact and castrated male leopard geckos (Eublepharis macularius).

Although the utility of analyzing behavioral experience effects on neural cytochrome oxidase (CO) activity is well recognized, the behavioral correlates of endogenous differences in CO activity have rarely been explored. In male leopard geckos (Eublepharis macularius), the incubation temperature experienced during embryogenesis (IncT) and age affect CO activity in the preoptic area (POA), an area that modulates copulatory behavior. In this study, the authors assessed whether differences in POA CO activity correlate with differences in sexual behavior in intact and castrated geckos. Males with IncT- and age-dependent increases in POA CO activity mounted females with shorter latencies while intact and after castration and ejaculated more frequently after castration. The authors discuss the predictive value of CO activity and propose similar parallels in other species.

Age Factors↗
PubMed1976

A model for cytochrome oxidase.

A model is proposed for the active center of cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) in which cytochrome a is a low-spin ferrihemoprotein and cytochrome a3 is a high-spin ferrihemoprotein antiferromagnetically coupled to one of the two Cu2+ ions present in the enzyme. It is further proposed that reduction is accompanied by a conformational change in the enzyme thus exposing the sixth coordination site of cytochrome a3 to ligands. With this model it is possible to account for a variety of outstanding observations including the results of magnetic circular dichroism, Mossbauer, and electron paramagnetic resonance spectroscopies, as well as magnetic susceptibility measurements.

Binding Sites↗
PubMed1996

The Bradyrhizobium japonicum fixGHIS genes are required for the formation of the high-affinity cbb3-type cytochrome oxidase.

We report structural and functional analyses of the Bradyrhizobium japonicum fixGHIS genes, which map immediately downstream of the fixNOQP operon for the symbiotically essential cbb3-type heme-copper oxidase complex. Expression of fixGHIS, like that of fixNOQP, is strongly induced in cells grown microaerobically or anaerobically. A fixGHI deletion led to the same prominent phenotypes as those known from a fixNOQP deletion: defective symbiotic nitrogen fixation (Fix-) and decreased cytochrome oxidase activity in cells grown under oxygen deprivation. Only traces, if any, of cytochrome cbb3 subunits were present in membranes isolated from the delta fixGHI strain, as revealed by Western blot analysis with subunit-specific antibodies. This effect was not due to lack of fixNOQP transcription. The results suggested a critical involvement of the fixGHIS gene products in the assembly and/or stability of the cbb3-type heme-copper oxidase. On the basis of sequence similarities between the FixI protein and a Cu-transporting P-type ATPase (CopA) of Enterococcus hirae, and between FixG and a membrane-bound oxidoreductase (RdxA) of Rhodobacter sphaeroides, we postulate that a membrane-bound FixGHIS complex might play a role in uptake and metabolism of copper required for the cbb3-type heme-copper oxidase.

Amino Acid Sequence↗
PubMed1988

Preparation of a one-subunit cytochrome oxidase from Paracoccus denitrificans: spectral analysis and enzymatic activity.

Cytochrome c oxidase was isolated from Paracoccus denitrificans as a two-subunit enzyme. Chymotrypsin-catalyzed proteolysis reduced the molecular weight of each subunit by about 8000. The spectral properties of this preparation, as well as its Km for cytochrome c(1.7 muM), remained unchanged with respect to the native enzyme. Vmax was reduced by about 55% when assayed in Triton X-100 or in Triton X-100 supplemented with asolectin. Following further proteolysis by Staphylococcus aureus V8 protease, subunit I remained unchanged as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas subunit II was split into small peptides. These were removed by ion-exchange high-performance liquid chromatography. The one-subunit enzyme had an apparent molecular weight of 43,000. The reduction of molecular weight was also confirmed by the diminution of the ultraviolet/Soret absorption ratio. This value was 1.8-2.1 for the native enzyme and 1.3-1.5 for the one-subunit enzyme. The spectral properties (including the spectrum CO reduced minus reduced) were not modified by the proteolytic treatment, indicating that cytochromes a and a3 were present in equal amounts. The lack of spectral alteration and the known close association of the copper B atom with cytochrome a3 suggest that copper B is also contained within the one-subunit enzyme. The Km of the one-subunit oxidase was similar to that of the two-subunit enzyme; Vmax was decreased by about 50%. The activity of the one-subunit oxidase had a salt-dependent maximum at 30 mM KCl, almost identical with that of the undigested enzyme, and was inhibited by micromolar concentrations of KCN.

Affinity Labels↗
PubMed1989

Cytochrome oxidase subunit II sequences in Petunia mitochondria: two intron-containing genes and an intron-less pseudogene associated with cytoplasmic male sterility.

The mitochondrial genome of Petunia hybrida contains two transcribed cytochrome oxidase subunit II (coxII) genes. The coding region of both genes is split by a 1.3 kb group II intron. Unlike coxII-1, which is similar to other sequenced plant coxII genes, the coxII-2 coding region is extended by 48 codons. The cytoplasmic male sterile (CMS) Petunia contains one coxII gene similar in structure and transcript pattern to the coxII-1 gene found in the fertile genome. Comparison of the sequenced coxII genes from the fertile mitochondrial genome with the coxII sequences present in the CMS-associated pcf gene from the CMS genome (Young and Hanson 1987) suggests that pcf is a processed pseudogene. A model for the generation of pcf is presented.

Amino Acid Sequence↗
PubMed1998

Oxidative stress and aging reduce COX I RNA and cytochrome oxidase activity in Drosophila.

Drosophila melanogaster displays an age-associated increase in oxidative damage and a decrease in mitochondrial transcripts. To determine if these changes result in energy production deficiencies, we measured the electron transport system (ETS) enzyme activity, and ATP levels with age. No statistically significant influences of age on activities of complexes I and II or citrate synthase were observed. In contrast, from 2 to 45 days post-eclosion, declines were found in complex IV cytochrome c oxidase activity (COX, 40% decline) and ATP abundance (15%), while lipid peroxidation increased 71%. We next examined flies that were either genetically or chemically oxidatively stressed to determine the effect on levels of mitochondrial-encoded cytochrome oxidase I RNA (coxI) and COX activity. A catalase null mutant line had 48% of coxI RNA compared to the wild type. In Cu/Zn superoxide dismutase (cSOD) null flies, the rate of coxI RNA decline was greater than in controls. CoxI RNA also declined with increasing hydrogen peroxide (H2O2) treatment, which was reflected in reduced cytochrome c oxidase (COX) activity. These results show that oxidative stress is closely associated with reductions in mitochondrial transcript levels and support the hypothesis that oxidative stress may contribute to mitochondrial dysfunction and aging in D. melanogaster.

Adenosine Triphosphate↗
PubMed1996

SERCA2a and mitochondrial cytochrome oxidase expression are increased in hearts of exercise-trained old rats.

Aging of rats results in slower activities of calcium transport by cardiac calcium adenosinetriphosphatase (ATPase) of the sarcoplasmic reticulum (SR) and mitochondrial cytochrome oxidase (COX). These enzyme activities are faster after exercise training of previously sedentary old rats. Our purpose was to determine whether the expression of the genes encoding SR calcium ATPase (SERCA2a) or COX is altered by exercise training. Old (24-mo-old) male Fischer 344 rats were assigned to SO (sedentary old) or EO (exercised old) groups and compared with younger (12-mo-old) sedentary rats (SM). EO rats were trained on a treadmill for 8-10 wk. SERCA2a and COX mRNAs were lower (P < 0.05) in SO compared with SM and EO, whereas glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and cardiac alpha-actin mRNAs were similar across groups. The immunoreactive protein contents of cardiac calcium ATPase, cytochrome c, sarcomeric actin, and GAPDH followed the changes, when observed, in mRNA contents. Thus pretranslational mechanisms may be modified in some genes during aging and exercise training of previously sedentary old rats.

Aging↗
PubMed1990

Densitometric analysis of cytochrome oxidase in ischemic rat brain.

Elevated brain lactate during incomplete ischemia is thought to contribute to the irreversibility of cell damage by interference with mitochondrial respiratory function, that should be evident in reduced cytochrome oxidase (CO) activity. In this study changes in the density of CO staining in a stroke model in the rat were assessed. Brains were analyzed subsequent to 30 min of ischemia followed by 30 min of reperfusion. The effects of postischemic treatment with sodium dichloroacetate (DCA)--a compound used to decrease lactate, were also evaluated. Examination of lateral cortex, hippocampus, and corpus striatum showed different intensities of CO in a distribution consistent with known regional variations in metabolic activity of the forebrain. Known laminar staining patterns in lateral cortex and areal patterns in the hippocampus were also confirmed. Comparable regions in ischemic forebrain were stained less densely for CO than controls. Image analysis demonstrated that the density of CO: (a) was greater in lateral cortex than hippocampus in control; (b) in ischemics was reduced by an equal degree in cortex and hippocampus; (c) lacked regional uniformity in ischemic rats; and (d) was not changed by DCA treatment in the majority of cases of ischemia. Our results suggest that lactate may not be the major determinant of 'selective vulnerability'. Despite elevated lactate levels in lateral cortex when compared to hippocampus in a previous study, the proportionate decrease in CO activity in lateral cortex and hippocampus was equal. However, there was a considerable decrease in CO activity subsequent to high brain lactate and some ischemic hemispheres appeared to respond to DCA treatment. Therefore, the role of excessive lactate in the exacerbation of 'selective vulnerability' warrants further evaluation. CO histochemistry can be used successfully to determine the distribution of pathology and the quality of fixation of ischemic forebrain. Densitometric measurements allowed comparative assessment of degrees of injury and the effects of treatment in discrete anatomical regions. This kind of analysis may allow localization of pathology within specific cellular circuits.

Acetates↗
PubMed1991

Cytochrome oxidase staining facilitates unequivocal visualization of the primary gustatory area in the fronto-operculo-insular cortex of macaque monkeys.

Fronto-opercular and insular cortices of Japanese macaques were histochemically stained for cytochrome oxidase activity. The laminated pattern of enzyme activity differed in the different cytoarchitectonic areas. Area G, the presumed primary gustatory area, as well as area 3 were prominent because the third stripe, corresponding to the termination layers of the specific thalamocortical projection in these areas was very dark and thick in comparison with that from the neighboring areas. This approach provides a convenient histological aid for identification of area G.

Animals↗
PubMed2002

Redox behavior of cytochrome oxidase and neurological prognosis in 66 patients who underwent thoracic aortic surgery.

OBJECTIVE: Using near-infrared spectroscopy (NIRS), we have developed a new approach to the measurement of the redox state of cytochrome oxidase (cyt. ox.) in the brain. Our previous animal study showed that oxygen-dependent redox changes in cyt. ox. occur only when oxygen delivery is badly impaired. Therefore, in this study, we retrospectively examined the relationship between the redox behavior of cyt. ox. (measured by NIRS) during an operation and the neurological outcome in patients. METHODS: We studied 66 patients undergoing thoracic aortic surgery with cardiopulmonary bypass. Cerebral oxygenation was monitored by NIRS, and relative values for the concentrations of oxy-Hb, deoxy-Hb, and the redox state of cyt. ox. in the brain were calculated using our developed algorithm. RESULTS: Retrospective assessment revealed three different types of cyt. ox. behavior: (1) no change (type-A) in 34 cases (51.5%), (2) a temporary reduction, with a subsequent return to the pre-surgery baseline level (type-B) in 29 cases (43.9%), or (3) a marked and prolonged reduction (type-C) in only three cases (4.5%). Nine of the 66 patients (13.6%; one type-A, five type-B, and all three type-C patients) showed evidence of postoperative brain injury (in the type-A patient, the injury proved to be localized and far from the monitoring site). The relationship between the occurrence of such an injury and the type of cyt. ox. behavior seen during the operation was highly significant (P<0.0001; chi-square test for independence). CONCLUSIONS: Our data suggest that the redox behavior of cyt. ox. during an operation is a good (though not perfect) predictor of postoperative cerebral outcome, and that overall tissue oxygen sufficiency can be confirmed by near-infrared measurement of cyt. ox.

Aortic Aneurysm, Thoracic↗
PubMed1993

Visual resolution and sensitivity of single cells in the primary visual cortex (V1) of a nocturnal primate (bush baby): correlations with cortical layers and cytochrome oxidase patterns.

1. This study describes the response properties of V1 cortical cells in a nocturnal primate and examines the receptive field organization of these cells in relationship to anatomically defined layers and cytochrome oxidase (CO) rich blobs and CO poor interblob compartments. Visual resolution and contrast sensitivity are consistent with other physiological and behavioral measures in this species. Comparisons are made with response properties of the same zones in macaque monkey, as well as of area 17 of a distantly related species (cat) that also occupies a nocturnal niche. 2. The responses of single cells to drifting sinusoidal gratings were recorded in V1 (striate cortex) of anesthetized, paralyzed bush babies (Galago crassicaudatus). Cells tended to be grouped with respect to ocular dominance, orientation preference, and direction selectivity. There was a high proportion of monocularly driven cells as in macaque monkey. Only 6% of the cells were nonoriented. These were poorly tuned complex cells and bore no resemblance to nonoriented lateral geniculate nucleus (LGN)-like cells reported in layer IV of macaque monkeys. Unidirectional cells were most frequently encountered in cortical layers that receive input from the magnocellular layers of the LGN. 3. Cells were classified as simple (31%) or complex (69%) according to standard criteria. Simple cells were significantly more narrowly tuned than complex cells for both orientation and spatial frequency. Complex cells had significantly higher average optimal spatial frequencies and spatial frequency cutoffs than simple cells. Contrast sensitivity of simple and complex cells averaged 38 and 34, respectively. Spatial resolution and sensitivity of these cells matches behavioral measures in bush baby. The spatial and temporal resolution of bush baby cells are similar to those of cats, which is likely related to the nocturnal niche of both species. 4. Cells in supragranular (I-III) and infragranular (V, VI) layers differed significantly in their response characteristics. The cells in the supragranular layers had significantly higher contrast sensitivity than did the cells in the infragranular layers. Cells in the supragranular layers likewise had higher temporal frequency cutoffs, significantly lower optimal spatial frequencies, lower spatial frequency cutoffs, and tighter orientation tuning than did cells in the infragranular layers. 5. Properties of cells in individual layers and CO blob and interblob compartments also showed differentiation. Layer III had the narrowest orientation and spatial frequency tuning with the tightest tuning in layer IIIC (IVB).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

[Variability of the mitochondrial gene for cytochrome oxidase I within the Adalia bipunctata species and within species of ladybird beetles (Coleoptera: Coccinellidae)].

Intergeneric, interspecific, and intraspecific genetic variation of the 310-bp 3'-end region of the mitochondrial gene of cytochrome oxidase I (COI) has been assessed in ladybirds (Coleoptera: Coccinnellidae). The phylogenetic distances between eight species of ladybirds have been determined. Mitochondrial DNA (mtDNA) nucleotide sequences have been compared in Adalia bipunctata L. differing in the elytron and pronotum colors that have been sampled from several geographically remote populations. The taxonomic statuses of two morphs from the genus Adalia, A. bipunctata bipunctata and A. bipunctata fasciatopunctata, have been identified.

Animals↗
PubMed2006

Molecular phylogeny of silk-producing insects based on 16S ribosomal RNA and cytochrome oxidase subunit I genes.

We have examined the molecular-phylogenetic relationships between nonmulberry and mulberry silkworm species that belong to the families Saturniidae, Bombycidae and Lasiocampidae using 16S ribosomal RNA (16S rRNA) and cytochrome oxidase subunit I (coxI) gene sequences. Aligned nucleotide sequences of 16S rRNA and coxI from 14 silk-producing species were used for construction of phylogenetic trees by maximum likelihood and maximum parsimony methods. The tree topology on the basis of 16S rRNA supports monophyly for members of Saturniidae and Bombycidae. Weighted parsimony analysis weighted towards transversions relative to transitions (ts, tv4) for coxI resulted in more robust bootstrap support over unweighted parsimony and favours the 16S rRNA tree topology. Combined analysis reflected clear biogeographic pattern, and agrees with morphological and cytological data.

Animals↗