Cytochrome Oxidase Levels Research Articles

Pathogenetic basis of optic nerve atrophy in methanol poisoning

Optic nerve atrophy is a pathomorphological consequence of diseases of the peripheral neuron of the visual pathway, manifested as atrophy of nerve fibers of varying severity. The toxic effect of methanol is mainly associated with formic acid and formaldehyde, which suppress the cytochrome system, inhibit oxidative phosphorylation, and thereby cause a deficiency of adenosine triphosphoric acid, to which brain and retinal tissues are especially susceptible. When formiate accumulates, tissue respiration is disrupted, leading to pronounced tissue hypoxia. As a result of such methanol metabolism, metabolic acidosis occurs. Tissue hypoxia develops in the first few hours as a result of the action of formic acid on the respiratory enzyme chain at the cytochrome oxidase level. Hypoxia and, as a consequence, a decrease in energy supply lead to a disruption of biological oxidation and the development of apoptosis in the optic nerve fibers. Understanding the process of optic nerve atrophy development at the pathogenetic level in methyl alcohol intoxication will help make a correct early diagnosis and prescribe timely treatment.

Erythropoietin and Bacillus Calmette-Guérin Vaccination Mitigate 3-Nitropropionic Acid-Induced Huntington-like Disease in Rats by Modulating the PI3K/Akt/mTOR/P70S6K Pathway and Enhancing the Autophagy.

Oxidative stress and mitochondrial dysfunction are among the mechanisms expected to explain the pathogenesis of Huntington's disease. Erythropoietin (EPO) and the Bacillus Calmette-Guérin (BCG) vaccine have neuroprotective effects against neurodegenerative diseases; however, the full mechanisms of their action are currently unclear. Here, for the first time, we investigated the neuroprotective effect of BCG vaccination in Huntington-like disease induced by 3-nitropropionic acid (3-NP) and its combination with EPO. Male Wistar rats were randomized into five groups: saline-treated control; 3-NP group (20 mg/kg/day, i.p.) for 7 days; EPO-treated group (5000 IU/kg/day, i.p.) for 14 days after 3-NP administration; live BCG vaccine prophylactic group (5000 cfu/g, i.p.) 10 days prior to 3-NP administration; and live BCG vaccine (5000 cfu/g, i.p.) 10 days before 3-NP administration, followed by EPO treatment (5000 IU/kg/day, i.p.) for 14 days. In a histopathological examination, striatum neurodegeneration was evidenced in the 3-NP injected rats. Administration of 3-NP elevated the levels of p-PI3K, p-Akt, p-mTOR, p-P70S6K, BAX, malondialdehyde, nitric oxide, and cytochrome oxidase while reduced the levels of BCL-2, superoxide dismutase, reduced glutathione, and the autophagy marker microtubule-associated protein light chain 3 in the striatum. EPO and BCG ameliorated the biochemical, histopathological, and behavioral derangements induced by 3-NP, with prominent neuroprotection observed in rats administered the BCG prophylactic combined with EPO treatment. These results highlight the role played by EPO and BCG in the management of 3-NP-induced Huntington-like disease by inhibiting the PI3K/Akt/mTOR/P70S6K pathway and enhancing the autophagy.

Progesterone Promotes Mitochondrial Respiration at the Biochemical and Molecular Level in Germinating Maize Seeds

This research aimed to investigate the effects of progesterone, a mammalian steroid sex hormone, on the mitochondrial respiration in germinating maize seeds. For this purpose, maize seeds were divided into four different groups (control, 10−6, 10−8, and 10−10 mol·L−1 progesterone) and were grown in a germination cabinet in the dark at 24.5 ± 0.5 °C for 4 d. The changes in gene expression levels of citrate synthase (CS), cytochrome oxidase (COX19), pyruvate dehydrogenase (Pdh1), and ATP synthase (ATP6), which is involved in mitochondrial respiration, were studied in root and cotyledon tissues. Significant increases were recorded in the gene expression levels of all studied enzymes. In addition, progesterone applications stimulated activities of malate synthase (MS), isocitrate lyase (ICL), and alpha-amylase, which are important enzymes of the germination step. The changes in gene expression levels of mas1 and icl1 were found parallel to the rise in these enzymes’ activities. It was determined similar increases in root and coleoptile lengths and total soluble protein and total carbohydrate contents. The most remarkable changes were detected in 10−8 mol·L−1 progesterone-treated seedlings. These results clearly indicate that progesterone stimulates mitochondrial respiration by inducing biochemical and molecular parameters and thus accelerates seed germination thanks to the activation of other pathways related to mitochondrial respiration.

Melatonin-related mitochondrial respiration responses are associated with growth promotion and cold tolerance in plants

Melatonin has the ability to improve plant growth and strengthened plant tolerance to environmental stresses; however, the effects of melatonin on mitochondrial respiration in plants and the underlying biochemical and molecular mechanisms are still unclear. The objective of the study is to determine possible effects of melatonin on mitochondrial respiration and energy efficiency in maize leaves grown under optimum temperature and cold stress and to reveal the relationship between melatonin-induced possible alterations in mitochondrial respiration and cold tolerance. Melatonin and cold stress, alone and in combination, caused significant increases in activities and gene expressions of pyruvate dehydrogenase, citrate synthase, and malate dehydrogenase, indicating an acceleration in the rate of tricarboxylic acid cycle. Total mitochondrial respiration rate, cytochrome pathway rate, and alternative respiration rate were increased by the application of melatonin and/or cold stress. Similarly, gene expression and protein levels of cytochrome oxidase and alternative oxidase were also enhanced by melatonin and/or cold stress. The highest values for all these parameters were obtained from the seedlings treated with the combined application of melatonin and cold stress. The activity and gene expression of ATP synthase and ATP concentration were augmented by melatonin under control and cold stress. On the other hand, cold stress reduced markedly plant growth parameters, including root length, plant height, leaf surface area, and chlorophyll content and increased the content of reactive oxygen species (ROS), including superoxide anion and hydrogen peroxide and oxidative damage, including malondialdehyde content and electrolyte leakage level; however, melatonin significantly promoted the plant growth parameters and reduced ROS content and oxidative damage under control and cold stress. These data revealed that melatonin-induced growth promotion and cold tolerance in maize is associated with its modulating effect on mitochondrial respiration.

Effects of neonatal hyperoxia on the critical period of postnatal development of neurochemical expressions in brain stem respiratory-related nuclei in the rat.

We have identified a critical period of respiratory development in rats at postnatal days P12‐13, when inhibitory influence dominates and when the response to hypoxia is at its weakest. This critical period has significant implications for Sudden Infant Death Syndrome (SIDS), the cause of which remains elusive. One of the known risk factors for SIDS is prematurity. A common intervention used in premature infants is hyperoxic therapy, which, if prolonged, can alter the ventilatory response to hypoxia and induce sustained inhibition of lung alveolar growth and pulmonary remodeling. The goal of this study was to test our hypothesis that neonatal hyperoxia from postnatal day (P) 0 to P10 in rat pups perturbs the critical period by altering the normal progression of neurochemical development in brain stem respiratory‐related nuclei. An in‐depth, semiquantitative immunohistochemical study was undertaken at P10 (immediately after hyperoxia and before the critical period), P12 (during the critical period), P14 (immediately after the critical period), and P17 (a week after the cessation of hyperoxia). In agreement with our previous findings, levels of cytochrome oxidase, brain‐derived neurotrophic factor (BDNF), TrkB (BDNF receptor), and several serotonergic proteins (5‐HT1A and 2A receptors, 5‐HT synthesizing enzyme tryptophan hydroxylase [TPH], and serotonin transporter [SERT]) all fell in several brain stem respiratory‐related nuclei during the critical period (P12) in control animals. However, in hyperoxic animals, these neurochemicals exhibited a significant fall at P14 instead. Thus, neonatal hyperoxia delayed but did not eliminate the critical period of postnatal development in multiple brain stem respiratory‐related nuclei, with little effect on the nonrespiratory cuneate nucleus.

Progression of experimental autoimmune encephalomyelitis (EAE) increases manganese superoxide dismutase (MnSOD) protein in the mitochondria of the mouse renal cortex

Abstract Sodium has been implicated in the high NaCl diet-induced exacerbation of EAE. The kidney cortex is the primary site for regulating Na homeostasis. Reabsorption of Na by the cortex absolutely relies on the ATP-dependent Na,K-ATPase. Our previous studies demonstrated that the progression of EAE increases the Na,K-ATPase activity in the cortex even under normal salt intake. Mitochondrial respiration not only generates ATP, but also produces reactive oxygen species (ROS). As MnSOD is the first line of defense against the harmful effect of mitochondrial ROS, the present study analyzed whether EAE had any effects on MnSOD. Progression of EAE from mild to severe stage increased total MnSOD protein by 38% and had no significant effect on CuZnSOD protein. This effect was not explainable solely by the illness-induced reduction of water or food intake. Further analyses reveals that severe EAE increased mitochondrial MnSOD protein by 47%, Na,K-ATPase beta1 subunit protein by 64% with a concomitant increase of mitochondrial function as measured by the complex II activity and protein level of cytochrome oxidase 4, a major component of complex IV. Activation of Na,K-ATPase with two mechanistically different reagents, monensin and dexamethasone, simulates the effect of EAE on MnSOD protein in HEK293 cells. Fluorescent microscopic study showed that monensin and dexamethasone increased ROS in HEK293 cells, and this effect was inhibited by 400 U/ml catalase. Similarly, catalase also erased the effects of monensin and dexamethasone on MnSOD protein. In conclusion, progression of EAE increases mitochondrial MnSOD protein in the kidney cortex, likely due to the ROS produced during respiration to meet the demands of ATP for the Na,K-ATPase.

Further insight into reproductive incompatibility between putative cryptic species of the Bemisia tabaci whitefly complex.

The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), with its global distribution and extensive genetic diversity, is now known to be a complex of over 35 cryptic species. However, a satisfactory resolution of the systematics of this species complex is yet to be achieved. Here, we designed experiments to examine reproductive compatibility among species with different levels of mitochondrial cytochrome oxidase I (mtCOI) divergence. The data show that putative species with mtCOI divergence of >8% between them consistently exhibited complete reproductive isolation. However, two of the putative species, Asia II 9 and Asia II 3, with mtCOI divergence of 4.47% between them, exhibited near complete reproductive compatibility in one direction of their cross, and partial reproductive compatibility in the other direction. Together with some recent reports on this topic from the literature, our data indicates that, while divergence in the mtCOI sequences provides a valid molecular marker for species delimitation in most clades, more genetic markers and more sophisticated molecular phylogeny will be required to achieve adequate delimitation of all species in this whitefly complex. While many attempts have been made to examine the reproductive compatibility among genetic groups of the B. tabaci complex, our study represents the first effort to conduct crossing experiments with putative species that were chosen with considerations of their genetic divergence. In light of the new data, we discuss the best strategy and protocols to conduct further molecular phylogenetic analysis and crossing trials, in order to reveal the overall pattern of reproductive incompatibility among species of this whitefly complex.

Effect of salt treatment on growth, isoenzymes and metabolites of Andrographis paniculata (Burm. f.) Nees

Andrographis paniculata is a well-known medicinal plant having vast therapeutic potentials. Efficient use of saline land for promoting the cultivation of medicinal plants is valuable for pharmaceutical and economic benefits. Relatively little is known about the physiological and biochemical basis of salt tolerance in this plant. Here, we studied the growth, isoenzymes, malondialdehyde, proline and secondary metabolites of A. paniculata in response to different salt treatments with NaCl (0, 41.1, 92.4, 143.7 and 193.4 mM). The results indicated that growth traits were decreased and all the expression level of superoxide dismutase (SOD), catalase (CAT), cytochrome oxidase (CYT), peroxidase (POD), polyphenol oxidase (PPO) and esterase (EST) isoenzyme in leaves and roots was enhanced with increasing salinity. Malondialdehyde was positively correlated to salt levels. Proline decreased at first and then dramatically increased at 193.4 mM. The content of key secondary metabolites was continuously increased under less than 143.7 mM NaCl concentrations. Results suggest that A. paniculata has relatively salt resistance by activating enzyme expressions both in roots and leaves, elicitation of secondary metabolites and osmoprotectant, but also reasonably regulating the allocation of resources. It is preferent to using resources for defense rather than for growth in A. paniculata and there is metabolic shift from growth to defense under salt conditions. Induction of isoenzyme activities and production of secondary metabolites are the primary defense strategies. Additionally, moderate salt treatment could promote the accumulation of bioactive phytocompounds, which is valuable for breeding plants with high quality. Thus, the cultivation of this medicinal herb in moderate saline areas could be considered as an agricultural option. Furthermore, our upshorts can provide a reference for screening better salt-tolerant cultivars of A. paniculata.

Co-localization of glutamic acid decarboxylase and vesicular GABA transporter in cytochrome oxidase patches of macaque striate cortex.

The patches in primary visual cortex constitute hot spots of metabolic activity, manifested by enhanced levels of cytochrome oxidase (CO) activity. They are also labeled preferentially by immunostaining for glutamic acid decarboxylase (GAD), γ-aminobutyric acid (GABA), and parvalbumin. However, calbindin shows stronger immunoreactivity outside patches. In light of this discrepancy, the distribution of the vesicular GABA transporter (VGAT) was examined in striate cortex of two normal macaques. VGAT immunoreactivity was strongest in layers 4B, 4Cα, and 5. In tangential sections, the distribution of CO, GAD, and VGAT was compared in layer 2/3. There was a close match between all three labels. This finding indicates that GABA synthesis is enriched in patches, and that inhibitory synapses are more active in patches than interpatches.

Carbohydrate concentrations and freezing stress resistance of silver birch buds grown under elevated temperature and ozone

The effects of slightly elevated temperature (+0.8 °C), ozone (O3) concentration (1.3 × ambient O3 concentration) and their combination on over-wintering buds of Betula pendula Roth were studied after two growing seasons of exposure in the field. Carbohydrate concentrations, freezing stress resistance (FSR), bud dry weight to fresh weight ratio, and transcript levels of cytochrome oxidase (COX), alternative oxidase (AOX) and dehydrin (LTI36) genes were studied in two clones (clones 12 and 25) in December. Elevated temperature increased the bud dry weight to fresh weight ratio and the ratio of raffinose family oligosaccharides to sucrose and the transcript levels of the dehydrin (LTI36) gene (in clone 12 only), but did not alter the FSR of the buds. Genotype-specific alterations in carbohydrate metabolism were found in the buds grown under elevated O3. The treatments did not significantly affect the transcript level of the COX or AOX genes. No clear pattern of an interactive effect between elevated temperature and O3 concentration was found. According to these data, the increase in autumnal temperatures and slightly increasing O3 concentrations do not increase the risk for freeze-induced damage in winter in silver birch buds, although some alterations in bud physiology occur.

Salivary Ferritin as a Predictive Marker of Iron Deficiency Anemia in Children

The objective of the study was to determine the salivary Ferritin levels in children with iron deficiency anemia and its reliability as a predictive marker of the disease and whether these levels could give a new hypothetical insight on the oral epithelial changes seen in patients with iron deficiency anemia. The study comprised of 60 children of which the study group comprised of 30 individuals; aged 8-14 years with iron deficiency anemia. Venous blood was collected and hematological examination was performed to determine the hemoglobin and serum ferritin levels to confirm the diagnosis. Saliva was then collected from 30 children with iron deficiency anemia and an equal number of controls. The ferritin levels in saliva were then analyzed using solid phase ELISA. The mean value of salivary ferritin in iron deficient cases was 153.24 +/- 46.58 microg/dl and the mean ferritin levels in control subject were 93.87 +/- 30.15 microg/dl. Thus the salivary ferritin was found to be significantly higher in iron deficient subjects compared to the controls. The result of our research affirms the fact that the expression of ferritin in saliva of iron deficiency anemia may be due to the enzymatic functions in the saliva and the endocytosis of ferritin which can possibly elevate the salivary ferritin. The diminished level of cytochrome oxidase, together with its relatively high Ferritin content, depicts the association of oral epithelial changes and ferritin occurring in iron deficiency anemia.

Metabolic and electrophysiological changes in the basal ganglia of transgenic Huntington's disease rats

Huntington's disease (HD) is characterized by neuronal loss in the striatum, ultimately leading to an ‘imbalance’ in the electrical activity of the basal ganglia-thalamocortical circuits. To restore this ‘imbalance’ in HD patients, which is held responsible for (some) of the motor symptoms, different basal ganglia nuclei have been targeted for surgical therapies, such as ablative surgery and deep brain stimulation. However, evidence to target brain nuclei for surgical therapies in HD is lacking. We reasoned that a neuronal and metabolic mapping of the basal ganglia nuclei could identify a functional substrate for therapeutic interventions. Therefore, the aim of the present study was to investigate the metabolic and neuronal activity of basal ganglia nuclei in a transgenic rat model of HD (tgHD). Subjects were 10–12month old tgHD rats and wildtype littermates. We examined the striatum, globus pallidus, entopeduncular nucleus, the subthalamic nucleus and substantia nigra at different levels. First, we determined the overall neuronal activity at a supracellular level, by cytochrome oxidase histochemistry. Secondly, we determined the subcellular metabolic activity, by immunohistochemistry for peroxisome proliferator-activated receptor-γ transcription co-activator (PGC-1α), a key player in the mitochondrial machinery. Finally, we performed extracellular single unit recordings in the nuclei to determine the cellular activity. In tgHD rats, optical density analysis showed a significantly increased cytochrome oxidase levels in the globus pallidus and subthalamic nucleus when compared to controls. PGC-1α expression was only enhanced in the subthalamic nucleus and electrophysiological recordings revealed decreased firing frequency of the majority of the neurons in the globus pallidus and increased firing frequency of the majority of the neurons in the subthalamic nucleus. Altogether, our results suggest that the globus pallidus and subthalamic nucleus play a role in the neurobiology of HD and can be potential targets for therapeutic interventions.

Dysregulation of mitochondrial sphingolipid metabolism after traumatic brain injury

To investigate mechanisms underlying a traumatic brain injury (TBI), we used a computer‐controlled cortical impact injury model in mice. The mouse brain injury was characterized by progressive cortical damage along with ablation of the grey and white matter demonstrated by magnetic resonance imaging and behavioral analysis. At the molecular level, TBI instigated a profound dysregulation of sphingolipid metabolism in brain. Sphingolipid analysis revealed increases in sphingomyelin and sphingosine that appear to result from activation of de novo biosynthesis of ceramide. Thus, the major metabolites of de novo ceramide biosynthetic pathway were up‐regulated after TBI. Remarkably, ceramide species were somewhat reduced concurrently with accumulation of sphingosine, possibly, due to enhanced ceramide degradation by ceramidase. Investigation of intracellular sites of sphingosine accumulation revealed the elevation of sphingosine in mitochondria. Furthermore, sphingosine accumulation appears to cause mitochondrial respiratory chain damage at the level of cytochrome oxidase that could be mimicked by exogenously added sphingosine to mitochondria. These studies highlight a novel mechanism of TBI injury involving dysregulation of sphingolipid metabolism in mitochondria and identify the sphingolipid responsible for mitochondrial dysfunction after TBI. Supported by VA Merit awards from RR&D and BLR&D Service.

Paeonol increases levels of cortical cytochrome oxidase and vascular actin and improves behavior in a rat model of Alzheimer's disease

Paeonol(2′-hydroxy-4′-methoxyacetophenone;1-(2-hydroxy-4-methoxyphenyl)ethan-1-one) is a constituent of the bark of the Moutan Cortex (Paeonia suffruticosa). This bark has been used as a traditional Chinese medicine and is reputed to possess a broad range of therapeutic properties probably by virtue of its anti-inflammatory and free radical scavenging properties. The effects of paeonol on a variety of biochemical and behavioral parameters were studied in rat brain in rat brain after experimental animals had been subjected to an intra-hippocampal injection of amyloid peptide, Aβ1–42. Sprague–Dawley rats were randomly divided into groups: saline, sham operated, β-amyloid (Aβ)-injected (intended to model Alzheimer's disease, (AD), and a group receiving both injected amyloid peptide and paeonol. Forty days after intra-hippocampal injection, H&E staining revealed that the lesions in the paeonol-treated group were significantly less than the untreated group. Levels of cytochrome oxidase and α-actin, determined immunohistochemically, were elevated in the paeonol treated group relative to the group receiving amyloid peptide alone. TUNEL staining revealed more apoptotic cells in the walls of the cerebral vascular elements in the AD model group than in the paeonol group. The paeonol-treated group also showed improvement in behavioral indices of learning relative to the group receiving Aβ1–42 alone, as judged using a Y-type electric maze. Treatment with paeonol can protect against many of the alterations resulting from administration of Aβ1–42. in a rat model of AD. These include morphological, biochemical and behavioral changes. Paeonol is a possible therapeutic measure in slowing down the pathogenic processes associated with AD.

Lipocalin 2 deficiency inhibits cell proliferation, autophagy, and mitochondrial biogenesis in mouse embryonic cells

Lipocalin 2 (LCN2) has been recently implicated as a critical player in multiple cancer tumorigeneses. However, the molecular mechanisms for its tumorigenic role are poorly understood. Herein, we investigated the effects of LCN2 on cell proliferation, autophagy, and mitochondrial biogenesis in MEF cells. We observed that LCN2 deficiency significantly inhibited cell proliferation and autophagy in MEF cells. Furthermore, mitochondrial DNA content, mRNA expression levels of mitochondrial-encoded gene cytochrome oxidase 2 and PGC-1α were all markedly reduced in LCN2⁻/⁻ MEF cells. Additionally, when compared with wild-type MEF cells, LCN2⁻/⁻ MEF cells expressed significantly higher levels of IRS-1, and displayed more potent TNFα-stimulated NF-κB activation. These findings demonstrate that LCN2 is a critical regulator of cell proliferation, autophagy, and mitochondrial biogenesis.

Phytic Acid as a Potential Treatment for Alzheimer's Pathology: Evidence from Animal and in vitro Models

Alzheimer's disease (AD) causes progressive, age-dependent cortical and hippocampal dysfunction leading to abnormal intellectual capacity and memory. We propose a novel protective treatment for AD pathology with phytic acid (inositol hexakisphosphate), a phytochemical found in food grains and a key signaling molecule in mammalian cells. We evaluated the protective and beneficial effects of phytic acid against amyloid-β (Aβ) pathology in MC65 cells and the Tg2576 mouse model. In MC65 cells, 48-72-hour treatment with phytic acid provided complete protection against amyloid precursor protein-C-terminal fragment-induced cytotoxicity by attenuating levels of increased intracellular calcium, hydrogen peroxide, superoxide, Aβ oligomers, and moderately upregulated the expression of autophagy (beclin-1) protein. In a tolerance paradigm, wild type mice were treated with 2% phytic acid in drinking water for 70 days. Phytic acid was well tolerated. Ceruloplasmin activity, brain copper and iron levels, and brain superoxide dismutase and ATP levels were unaffected by the treatment. There was a significant increase in brain levels of cytochrome oxidase and a decrease in lipid peroxidation with phytic acid administration. In a treatment paradigm, 12-month old Tg2576 and wild type mice were treated with 2% phytic acid or vehicle for 6 months. Brain levels of copper, iron, and zinc were unaffected. The effects of phytic acid were modest on the expression of AβPP trafficking-associated protein AP180, autophagy-associated proteins (beclin-1, LC3B), sirtuin 1, the ratio of phosphorylated AMP-activated protein kinase (PAMPK) to AMPK, soluble Aβ1-40, and insoluble Aβ1-42. These results suggest that phytic acid may provide a viable treatment option for AD.

Nodularin uptake and induction of oxidative stress in spinach ( Spinachia oleracea)

The bloom-forming cyanobacterium Nodularia spumigena produces toxic compounds, including nodularin, which is known to have adverse effects on various organisms. We monitored the primary effects of nodularin exposure on physiological parameters in Spinachia oleracea. We present the first evidence for the uptake of nodularin by a terrestrial plant, and show that the exposure of spinach to cyanobacterial crude water extract from nodularin-producing strain AV1 results in inhibition of growth and bleaching of the leaves. Despite drastic effects on phenotype and survival, nodularin did not disturb the photosynthetic performance of plants or the structure of the photosynthetic machinery in the chloroplast thylakoid membrane. Nevertheless, the nodularin-exposed plants suffered from oxidative stress, as evidenced by a high level of oxidative modifications targeted to various proteins, altered levels of enzymes involved in scavenging of reactive oxygen species (ROS), and increased levels of α-tocopherol, which is an important antioxidant. Moreover, the high level of cytochrome oxidase (COX II), a typical marker for mitochondrial respiratory protein complexes, suggests that the respiratory capacity is increased in the leaves of nodularin-exposed plants. Actively respiring plant mitochondria, in turn, may produce ROS at high rates. Although the accumulation of ROS and induction of the ROS scavenging network enable the survival of the plant upon toxin exposure, the upregulation of the enzymatic defense system is likely to increase energetic costs, reducing growth and the ultimate fitness of the plants.

Architectonic subdivisions of neocortex in the gray squirrel (Sciurus carolinensis).

Squirrels are highly visual mammals with an expanded cortical visual system and a number of well-differentiated architectonic fields. To describe and delimit cortical fields, subdivisions of cortex were reconstructed from serial brain sections cut in the coronal, sagittal, or horizontal planes. Architectonic characteristics of cortical areas were visualized after brain sections were processed with immunohistochemical and histochemical procedures for revealing parvalbumin, calbindin, neurofilament protein, vesicle glutamate transporter 2, limbic-associated membrane protein, synaptic zinc, cytochrome oxidase, myelin or Nissl substance. In general, these different procedures revealed similar boundaries between areas, suggesting that functionally relevant borders were being detected. The results allowed a more precise demarcation of previously identified areas as well as the identification of areas that had not been previously described. Primary sensory cortical areas were characterized by sparse zinc staining of layer 4, as thalamocortical terminations lack zinc, as well as by layer 4 terminations rich in parvalbumin and vesicle glutamate transporter 2. Primary areas also expressed higher levels of cytochrome oxidase and myelin. Primary motor cortex was associated with large SMI-32 labeled pyramidal cells in layers 3 and 5. Our proposed organization of cortex in gray squirrels includes both similarities and differences to the proposed of cortex in other rodents such as mice and rats. The presence of a number of well-differentiated cortical areas in squirrels may serve as a guide to the identification of homologous fields in other rodents, as well as a useful guide in further studies of cortical organization and function.

Plant mitochondrial function during anaerobiosis.

Under hypoxic conditions, plant mitochondria preserve the capacity to oxidize external NADH, NADPH and tricarboxylic acid cycle substrates. Nitrite serves as an alternative electron acceptor at the level of cytochrome oxidase, with possibly complex III and the alternative oxidase also being involved. Nitric oxide is a significant product of the reaction, which has a high affinity for cytochrome c oxidase, inhibiting it. The excess NO is scavenged by hypoxically induced class 1 haemoglobin in the reaction involving ascorbate. By using nitrite, mitochondria retain a limited capacity for ATP synthesis. NADH, produced from glycolysis during anaerobiosis and oxidized in the mitochondrial electron transport chain, should shift the composition of metabolites formed during anaerobiosis with increased conversion of pyruvate to alanine and greater involvement of other transamination reactions, such as those involving gamma-aminobutyric acid formation. Anaerobic mitochondrial metabolism may have a more significant role than previously thought in alleviating the effects of anoxia on plant cells. There is a need to re-examine mitochondrial carbon and nitrogen metabolism under anoxia to establish the extent of this involvement.

Exposure to GSM 900 MHz electromagnetic fields affects cerebral cytochrome c oxidase activity

The world-wide and rapidly growing use of mobile phones has raised serious concerns about the biological and health-related effects of radio frequency (RF) radiation, particularly concerns about the effects of RFs upon the nervous system. The goal of this study was conducted to measure cytochrome oxidase (CO) levels using histochemical methods in order to evaluate regional brain metabolic activity in rat brain after exposure to a GSM 900 MHz signal for 45 min/day at a brain-averaged specific absorption rate (SAR) of 1.5 W/Kg or for 15 min/day at a SAR of 6 W/Kg over seven days. Compared to the sham and control cage groups, rats exposed to a GSM signal at 6 W/Kg showed decreased CO activity in some areas of the prefrontal and frontal cortex (infralimbic cortex, prelimbic cortex, primary motor cortex, secondary motor cortex, anterior cingulate cortex areas 1 and 2 (Cg1 and Cg2)), the septum (dorsal and ventral parts of the lateral septal nucleus), the hippocampus (dorsal field CA1, CA2 and CA3 of the hippocampus and dental gyrus) and the posterior cortex (retrosplenial agranular cortex, primary and secondary visual cortex, perirhinal cortex and lateral entorhinal cortex). However, the exposure to GSM at 1.5 W/Kg did not affect brain activity. Our results indicate that 6 W/Kg GSM 900 MHz microwaves may affect brain metabolism and neuronal activity in rats.