Cytochrome C Oxidase Research Articles (Page 1)

Complex IV of the mitochondrial respiratory chain, or cytochrome c oxidase (CcO), contributes to the proton motive force necessary for ATP synthesis. CcO can slow the formation of reactive oxygen species and is key to physiology and drug development. The exact molecular mechanisms underlying its proton-pumping function remain elusive. The redox state of CcO's metallic cofactors is intimately connected to structural changes and proton pumping via proton-coupled electron transfer. Time-resolved UV/Vis and IR spectroscopy are used to investigate the effects of the electronic backreaction triggered by photolyzing the CO-inhibited 2-electron reduced state, R2CO, in the aa3 oxidase from Cereibacter sphaeroides. An intermediate is identified, in which the binuclear center matches the redox state of the catalytic intermediate E (one-electron reduced state), with a rise time of ≈2 μs. The electron transfer induces structural changes that lead to E286 deprotonation, with a time constant of 13 μs. Thus, it is inferred that transient reduction of heme a alone drives E286 deprotonation. E286 is reprotonated with a time constant of 72 ms when CO rebinds. The results support the view that transient heme a reduction in the physiological E state modulates the electrostatic environment, triggering proton transfer toward the proton-loading site.

A new species from Hubei Province, China (Oriental region), Sympotthastia annularis sp. nov. is described and illustrated based on the adult male. A key to the known males of Sympotthastia worldwide is additionally provided. The mitochondrial cytochrome c oxidase subunit I (COI) gene of the new species was sequenced and submitted to the National Center for Biotechnology Information (NCBI). Based on the new species’ COI sequence data and those of 19 other Sympotthastia sequences obtained from existing public databases NCBI, phylogenetic relationships within the genus were inferred, placing the new species closest to Sympotthatsia takatensis (Tokunaga, 1936). The molecular analysis of cytochrome oxidase (COI) genes and the obtained minimum interspecific K2P distance to the closest species, S. takatensis (5.9%), further confirms the species status of the new species.

Genome-wide identification of cytochrome c oxidase genes in cotton and functional characterization of GhCOX11 in drought and cold stress.

The relationship between mitochondrial respiration metabolism, energy efficiency and ultraweak luminescence in strawberry fruit.

Liquid-phase determination of Arabidopsis respiration and photosynthesis using Clark-type O2 electrodes.

Nail infections are common but challenging to treat. Oral treatments can be effective but may cause adverse effects and drug interactions, while topical treatments only work in about a third of patients due to poor penetration of antifungals into the nail plate. Small polar molecules, such as hydrogen sulphide (H2S), penetrate readily into the nail plate, and previous studies have shown that H2S has antimicrobial properties. Using the donor sodium hydrogen sulphide (NaHS), we found that H2S has potent activity against causative agents of nail infections, including fungi and bacteria. The most active form appeared to be H2S, not the anion HS−, but this was most likely related to the faster cellular uptake of H2S. We showed that H2S inhibits cytochrome C oxidase (COX), a key respiratory enzyme, increases reactive oxygen species and protein S-sulfhydration. Transcriptomic analysis revealed a stress response, with 96 genes upregulated and 117 downregulated, indicating efforts to reduce oxidative stress. COX inhibition likely causes electron leakage, generating ROS and oxidising cysteine residues, which then react with H2S to form S-sulfhydrated proteins. This novel mechanism, along with the ability of H2S to penetrate the nail, suggests topical delivery of an H2S donor is a promising new treatment for onychomycosis.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-22062-7.

Tomato (Solanum lycopersicum) is a climacteric fruit displaying a respiration peak at the onset of ripening accompanied by increased synthesis of ethylene and carotenoid pigments. Chromoplast and mitochondrial respiration participate at different stages of fruit ripening, but their in vivo regulation and function remain unclear. We determined the in vivo activities of the mitochondrial alternative oxidase (AOX) and cytochrome oxidase pathways and quantified the levels of respiratory- and ripening-related gene transcripts, primary metabolites and carotenoids in ripening tomato fruits with or without functional chromorespiration. Furthermore, we carried out physiological, molecular, and metabolic analyses of CRISPR-Cas9 mutants defective in AOX1a, the main AOX isoform upregulated during tomato fruit ripening. We confirmed that plastid terminal oxidase-dependent chromorespiration is only relevant at late stages of ripening and found that in vivo AOX activity significantly increased at the breaker stage, becoming the main contributor to climacteric respiration when ripening initiates. This activation did not correlate with gene expression but was likely due to increased levels of AOX activators such as pyruvate (a metabolic precursor of carotenoids), 2-oxoglutarate, and succinate. A strong alteration of ripening-related metabolites was observed in aox1a mutant fruits, highlighting a key role of the AOX pathway at the onset of ripening. Our data suggest that increased supply of tricarboxylic acid cycle intermediates at the climacteric stage allosterically enhances AOX activity, thus allowing the reoxidation of NAD(P)H to ensure carbon supply for triggering ethylene and carotenoid biosynthesis.

West Nile Virus (WNV) is an emerging arboviral threat in Europe, with rising incidence in Spain since 2004. In 2024, Spain experienced its largest outbreak, primarily in small urban areas of south-western regions. We report a subset of an emergency integrated vector management program, focusing on six municipalities accounting for one-third of all human WNV cases nationwide. Over four months, 725 potential larval sites were inspected during 4026 visits. Adult mosquitoes (n = 2553) were collected with suction traps, and immature stages (n = 4457) with dipper techniques, yielding 11 species. Culex pipiens s.l. was predominant, while Cx. perexiguus, though less abundant, was epidemiologically significant. Cytochrome Oxidase I (COI) gene phylogenetic analysis confirmed Cx. perexiguus, forming a distinct clade from Cx. univittatus. Immature mosquitoes were found in 18.6% of sites, especially irrigation canals, ditches, and backwaters near urban areas. Habitat differences in larval abundance were analyzed using generalized linear mixed models. Targeted larviciding with Bacillus thuringiensis var. israelensis (Bti) and focal adulticiding with cypermethrin totaled 259 interventions (70.4% larviciding, 29.6% adulticiding). A significant 63.9% reduction in larval abundance was observed after five consecutive Bti treatments, with some variation among treatment cycles (52.2–75.5%). Adult activity persisted into late autumn. This study provides the first comprehensive characterization of larval mosquitoes in Spain’s main WNV hotspot, highlighting the need for rapid, coordinated expert interventions and extended seasonal control to prevent future outbreaks.

BackgroundSpirocerca lupi is a nematode that infects domestic dogs and wild carnivores.MethodsThis study retrospectively analyzed postmortem records between 1989 and 2024 to assess S. lupi-associated lesions in coyote necropsies. In addition, it conducted molecular characterization of 18S rRNA and cytochrome oxidase subunit 1 (cox1) gene fragments of larvae found at necropsies. Fecal samples from free-ranging coyotes were molecularly examined for S. lupi18S DNA.ResultsOf the 39 coyote cases, 33 (84. 6%) presented S. lupi-associated lesions. A significant association was observed between the presence of Spirocerca nematodes and the development of esophageal granulomas and aortic aneurysms. In addition, an atypical case of spinal cord invasion was documented, representing the first reported occurrence of this condition in coyotes. Out of all fecal samples tested, 4.6% were positive for S. lupi infection.ConclusionsThe obtained cox1 sequence revealed a complete similarity to S. lupi isolated from the Andean fox Lycalopex culpaeus from Peru, suggesting its transmission between wild canid populations. These findings indicate that coyotes play a significant role in S. lupi transmission dynamics and highlight the need for further research on the ecological interactions between domestic and wild canids in Costa Rica.Graphical abstractSupplementary InformationThe online version contains supplementary material available at 10.1186/s13071-025-07030-4.

Azaleas (Ericaceae) are among the most diverse ornamental plants, celebrated for their cultural and economic significance. R. simsii has been extensively utilized in horticulture as a parent species for both “pot azalea” cultivars and various cultivars grown in the warmer regions of China. From 2021 to 2023, approximately 15% of R. simsii in nurseries situated in the Xuanwu District, Nanjing, exhibited symptoms of wilting and chlorosis. Investigations revealed that these symptoms were caused by a pathogen responsible for crown and root rot. Strains were isolated from the roots of affected plants. The morphology of the colonies was predominantly radial to stellate, characterized by intercalary and terminal hyphal swelling. The sporangia appeared spherical, pyriform, or ovoid with a single papillae. For accurate identification, the 28S rDNA gene (Large subunit, LSU), cytochrome oxidase subunit I (COXI), and cytochrome oxidase subunit II (COXII) genes were amplified through PCR and then sequenced. The species was identified as P. vexans after completing the phylogenetic analysis. Healthy R. simsii plants were infected with zoospores and developed symptoms similar to those of natural infection. Furthermore, the morphological characteristics of the isolates from the experimentally infected plants were similar to those of the original inoculated strains. This study identified P. vexans as the pathogen causing root rot in R. simsii. During the sampling process, several strains were isolated from the rhizosphere soil of healthy rhododendron plants. Based on this, research was immediately initiated to explore whether there are specific bacterial species in the soil that have the potential to inhibit the occurrence of root rot. Additionally, an endophytic bacterial strain BL1 was isolated from rhizosphere soil and subjected to Whole-Genome Shotgun (WGS) sequencing, thus constructing a bacterial genome framework for this isolate. The strain BL1 was identified as Bacillus licheniformis. To our knowledge, this is the first report of the occurrence of P. vexans causing crown and root rot of R. simsii in China. In this study, we also focused on exploring the potential of biological control agents against P. vexans. The isolation and identification of the endophytic bacterial strain BL1 (Bacillus licheniformis) from the rhizosphere soil of healthy soil show strong in vitro antagonism, identifying it as a promising candidate for future biological control studies of root rot in R. simsii. The genomic component analysis and coding gene annotation of BL1 provide insights into its genetic makeup and potential mechanisms of action against pathogens. However, these findings are based on in vitro assays. Therefore, further research, including in planta experiments, is essential to confirm the efficacy of BL1 in controlling P. vexans infections in R. simsii and to evaluate its potential for practical application.

The energy requirement of renal proximal tubular cells depends on mitochondrial fatty acid β-oxidation. Enoyl-CoA hydratase-l-3-hydroxyacyl-CoA dehydrogenase (EHHADH) is a crucial enzyme in mitochondrial fatty acid oxidation, and mutations in EHHADH reportedly cause Fanconi syndrome. Here, we report the case of a 28-year-old Japanese woman with a long-term history of low-molecular-weight proteinuria (LMWP) who exhibited a missense mutation in the EHHADH gene. She was diagnosed with LMWP at 4years of age. The search for the CLCN5 gene was unremarkable, and kidney biopsy revealed no significant tubulointerstitial changes. The LMWP persisted, and glucosuria gradually developed thereafter. Unexpectedly, next-generation sequencing identified a heterozygous missense mutation in the EHHADH gene. Her father, who harbored LMWP, also had the same mutation. Furthermore, immunostaining of the stored kidney specimens showed decreased immunoreactivity for cytochrome coxidase subunit 4 in the proximal tubules, suggesting an underlying mitochondrial impairment.

Cytochrome c oxidase is one of the most important mitochondrial enzymes. It catalyzes the formation of water from molecular oxygen by oxidizing reduced cytochrome c in the mitochondrial respiratory chain. These reactions are associated with proton transfer across the inner mitochondrial membrane, which ensures the formation of an electrochemical gradient. The localization of mitochondria in the brain structures, in particular its cortex, has a strongly marked functional character: the use of energy in brain tissues is closely related to the neuronal activity. Neurons are extremely dependent on glucose as the main substrate and on oxidative phosphorylation as the major process for ATP formation. In addition, neurons are very susceptible to cellular damage if deprived of metabolic substrates even for a few minutes. These biochemical properties, combined with the high metabolic needs of neurons, are responsible for the close relationship between neuronal activity and oxidative energy metabolism in the brain. In our work we consider the influence of heterogeneity of cytochrome c oxidase distribution in neurons of the mammalian visual cortex. Modeling of an ensemble of protein complexes is combined with the use of a virtual simulator approach of cytochrome oxidase activity.

Photobiomodulation enhances cognitive function in aging rats and modulates cytochrome c oxidase activity and c-Fos expression in memory-related circuits.

After peripheral nerve lesion, the role of reactive oxygen species (ROS) has not been clarified during Wallerian degeneration. The present study examined the participation of oxidant stress after rat sciatic nerve injury induced by two experimental models (crush and transection). Here, biochemical parameters indicative of oxidant stress, nitric oxide (NO) metabolism, cell proliferation, apoptosis, and bioenergetics were determined in injured and contralateral sciatic nerves and caudofemoralis muscle. After crushing, we found two peaks of increased lipid peroxidation (LP) by-products and carbonylation of proteins in crushed nerves. In transected nerves, increases in LP showed similar patterns in both proximal and distal nerve. In both models, NO production was decreased and accompanied by an early increase in cell proliferation. Moreover, caspase-3 activity increased later only in crushed nerves. NAD availability and mitochondrial cytochrome oxidase activity were increased in transected but not in crushed nerves. The contralateral nerves also had changes in these parameters, but in a differential manner depending on the type of nerve lesion. In conclusion, present data suggest that changes in the patterns of LP may play a regulatory role in cell damage and death, somehow exerting a control in the progression of Wallerian degeneration.

The West Palearctic genus Heterotoma Lepeletier & Serville, 1825, and its included species H. planicornis (Pallas, 1772) (Hemiptera, Heteroptera, Miridae, Orthotylinae) are reported from the Korean Peninsula. Heterotoma planicornis is diagnosed, and its dorsal habitus and the genitalia of both sexes are illustrated. The possible introduction of this European species into the Korean Peninsula is discussed. The complete mitochondrial genome of the species is provided. The circular mitogenome of H. planicornis is 16,179 bp long, comprising 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNAs, and shows the same gene order as the closely allied species Mecomma ambulans (Fallén, 1807). The A–T content of the total sequence was 71.54%. An analysis using a cytochrome oxidase I (COI) neighbor-joining (NJ) tree revealed that the Korean H. planicornis population formed two distinctive groups, with a 1.8% sequence difference between them.

BackgroundHyalomma marginatum is a hard tick vector of various pathogens, including Crimean-Congo Hemorrhagic fever virus, recently detected in French specimens. This species has a wide distribution from North Africa to Eastern Europe and has only recently been considered established in Southern France. These changes in species distribution led us to explore the genetic structure of tick populations in the Mediterranean basin and attempt to infer the origin of French populations. MethodsWe used two mitochondrial markers (12S rRNA and Cytochrome Oxidase 1) and genotyped ticks from nine Mediterranean countries. We compared genetic indices and haplotypic composition between these countries and the various French geographical populations.ResultsAcross all countries, we showed significant genetic differentiation, with a certain proximity between neighboring countries. We found very different genetic compositions among the French geographic populations: some exhibited signs of recent expansion, while others suggested the presence of ancient populations. ConclusionsIt is possible that small populations of H. marginatum were already present in France and are now more abundant. This recent change in population structure could be owing to increased human activity and climate change. These factors, combined with a potentially high level of phenotypic plasticity, could facilitate H. marginatum conquest of more northerly latitudes in France and other European countries.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1186/s13071-025-06927-4.

<i>Zeugodacus cucurbitae</i> or melon fly formerly called <i>Bactrocera cucurbitae</i> is an agricultural pest of Asian origin. Well known as a pest of fleshy fruits and vegetables damaging 81 host plants, the melon fly has been the subject of several studies due to its introduction and dissemination worldwide. Up to now, no study on the global structuring of <i>Zeugodacus cucurbitae</i> has been done. Therefore, knowledge of its genetic structuring would allow better management of the insect. It is in this context that the present study on the genetic characterization of populations of <i>Z. cucurbitae</i> watermelon pest insect fits. Our data was collected from the Genbank database. Phylogeographic analyses were made using mitochondrial cytochrome oxidase I (COI) DNA as a genetic marker. After analysis, the study demonstrated two distinct groups: a group composed of the population of Reunion and another group composed of populations from Africa, Asia, Oceania, and Hawaii. This is the result of a genetic isolation demonstrated by the Mantel Test for which the significant p-value confirms the correlation between genetic distances and geographical distances. However, there is a genetic differentiation between individuals in the Reunion population. For any fight against this insect, it would be interesting to take into account the existence of these two genetic groups.

In April of 2024, Cannabis sativa (L.) cuttings of 5 different cultivars (JUNK, GAR, SHOR, PBR, and ASNK) at indoor facilities in Mt. Dora and Homestead, FL were observed to have stunting, damping off, crown rot, and chlorosis. Of the 3,000 plants in the affected room, about 5-7% displayed the symptoms described. Pathogen identification was performed on 6 cuttings (cv. ASNK) from Homestead and 4 cuttings (cv. GAR and SHOR) from Mt. Dora. In a laminar flow hood, stems were surface sterilized in a 0.625% sodium hypochlorite solution for 2 min, rinsed in sterile deionized (DI) water, and cut into 1cm long segments. The segments were plated on both potato dextrose and V8 agar plates and incubated in the dark at 27°C for 48 hours. On V8 agar, dense aerial mycelia grew out from the stem segments. On PDA, the mycelium was fluffy and cotton-like, consistent with Pythium morphology (Kageyama, 2014). DNA from the mycelium was extracted using Quick DNA Fungal/Bacterial Kit (Zymo Research Irvine, CA, USA). The identities were confirmed with Internal Transcribed Spacer region (ITS) (Riit et al. 2016) sequences for two isolates which had 100% identity to P. myriotylum accession KX671096.1; and cytochrome oxidase subunit 1 (COI) (Robideau et al. 2011) sequences which had 99.69% identity to MT222351.1 using the BLASTn function of NCBI. The sequences were deposited into GenBank with accession nos. PQ143175 (ITS), PQ206192 (ITS), PQ206366 (COI), and PQ219680 (COI). A phylogenetic tree was constructed with MEGA software using concatenated ITS and COI sequences to show evolutionary relationships between these two P. myriotylum isolates and other Pythium/Globisporangium species. To prove pathogenicity, a pure culture of P. myriotylum was diced and transferred to 500 mL of V8 broth. A negative control was prepared using sterile V8 broth. The broths were placed on a rotary shaker and incubated at 150 rpm and 30°C for 72 hours. Light microscopy verified the presence of mycelial growth and motile zoospores in the inoculated broth and the absence of growth in the negative control. A total of 36 rockwool cubes were sterilized, 18 were soaked in the inoculated broth and 18 in the control broth for 30 minutes. Then, 36 cuttings were harvested from C. sativa plants (cv. CL1 and CL2), dipped in rooting gel (Clonex Rooting Gel, Growth Technology, Somerset, UK), and inserted into each rockwool cube. These cuttings were grown indoors in a humidity dome at 25°C under LED lights with an 18-hour photoperiod. After 6 days, infected clones exhibited damping off, wilting, and chlorosis. No symptoms were observed in the negative control plants. Crown sections of 5 symptomatic clones and 3 control clones were surface sterilized and plated onto V8 agar as previously described and incubated for 3 days at 27°C. Mycelial growth was observed from crown segments of inoculated plants and not from the control plants. Koch’s postulates were confirmed through re-isolation and amplification of the same ITS and COI regions from mycelial growth; sequences were identical to the originally isolated cultures. P. myriotylum has been previously described as causing disease symptoms in Cannabis (Punja, 2021). Since the cannabis industry currently relies on clonal propagation for cultivation and production, a P. myriotylum infection has the potential to cause economic damage. To our knowledge, this is the first report of P. myriotylum causing disease in Cannabis in Florida.

Genetic characterization of Rhipicephalus microplus (Acari: Ixodidae) in Africa reveals the presence of diverse haplotypes within a single clade: Implications for pathogens transmission and tick control in a predominantly pastoral production system.

Coffin flies (Diptera: Phoridae) are crucial to forensic studies because they can inhabit coffins or be found on buried corpses, thus aiding in determining the postmortem interval (PMI) and body relocation in criminal cases. But phorid flies are hard to identify because they are small, have cryptic appearances, and lack the proper taxonomic expertise to quickly identify both adult and larval forms. Thus, entomologists tend to concentrate increasingly on alternative methods to expedite the identification process and circumvent this problem. A short mitochondrial cytochrome oxidase I (COI) gene fragment is a potent marker for accurate molecular identification and robust phylogenetic analysis. Three phorid fly species, belonging to the genera Megaselia and Puliciphora, were collected in the current study to evaluate the effectiveness of the COI gene in identifying them. Seven sequences representing three species were generated and uploaded to GenBank and BOLD. COI barcodes successfully differentiated between species, with Kimura-2-Parameter (K2P) intraspecific and interspecific genetic divergences ranging from 0% to 1% and 14.5% to 34.1%, respectively. NJ (Neighbour-Joining), ML (Maximum-Likelihood), and BA (Bayesian Analysis) methods demonstrated strong reciprocal monophyly and accurate species differentiation. This study provides the first COI barcodes of M. rufipes and P. borinquenensis from India. The present study demonstrates the reliability of COI barcoding as a molecular method for identifying phorid species. Forensic entomological evidence would be improved by the inclusion of regional COI sequences in reference libraries, such as GenBank and BOLD, thus serving as essential forensic markers for criminal investigations and wildlife poaching cases.