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At least 433 records · Page 24Linked to original sources
PubMed2006

Interactions between nitric oxide, oxygen, reactive oxygen species and reactive nitrogen species.

ROS (reactive oxygen species) and RNS (reactive nitrogen species) are central to the innate immunity that protects us from infection, but also contribute to degenerative diseases and possibly aging. However, ROS and RNS are increasingly recognized to contribute to physiological signalling. This review briefly describes the main interactions between ROS and RNS and shows how their origins, chemistry, metabolism and biological actions are intimately linked.

Cell Death↗
PubMed2003

Glycated high-density lipoprotein regulates reactive oxygen species and reactive nitrogen species in endothelial cells.

Nonenzymatic glycosylation of plasma proteins may contribute to the excess risk of developing atherosclerosis in patients with diabetes mellitus. Although it is believed that high-density lipoprotein (HDL) is glycosylated at an increased level in diabetic individuals, little is known about a possible linkage between glycated HDL and endothelial dysfunction in diabetes. To clarify whether glucose-modified HDL affects the function of endothelial cells, we first examined herein the level of H(2)O(2) generation from cultured human aortic endothelial cells (HAECs) exposed to a glycated oxidized HDL (gly-ox-HDL) prepared in vitro. Incubation for 48 hours with 100 microg/mL of gly-ox-HDL induced significant release of H(2)O(2) from cells and gly-ox-HDL-induced H(2)O(2) formation was inhibited in the presence of diphenyleneiodonium, an inhibitor of NADPH oxidase. In addition, stimulation of HAECs with gly-ox-HDL for 48 hours elicited a marked downregulation of catalase and Cu(2+), Zn(2+)-superoxide dismutase (CuZn-SOD), suggesting H(2)O(2) formation by gly-ox-HDL to be due to a disturbance involving oxidant and antioxidant enzymes in the cells. Treatment of HAECs with gly-ox-HDL attenuated the expression of endothelial nitric oxide synthase (eNOS), but not inducible nitric oxide synthase (iNOS), and this was followed by decreased production of nitric oxide (NO) by the cells. Furthermore, in vitro experiments with glycated HDL (gly-HDL) in the presence of 2 mmol/L EDTA and Cu(2+)-oxidized HDL suggested the effect of gly-HDL on endothelial function to be possibly potentiated by additional oxidative modification. Taking all of the above findings together, gly-ox-HDL may lead to the deterioration of vascular function through altered production of reactive oxygen species and reactive nitrogen species in endothelial cells.

Blotting, Western↗
PubMed2006

Production of reactive oxygen species and reactive nitrogen species by angiosperm stigmas and pollen: potential signalling crosstalk?

Angiosperm stigmas exhibit high levels of peroxidase activity when receptive to pollen. To explore possible function(s) of this peroxidase activity we investigated amounts of reactive oxygen species (ROS), particularly hydrogen peroxide, in stigmas and pollen. Because nitric oxide (NO) was recently implicated in pollen tube growth, we also investigated amounts of NO in pollen and stigmas. Reactive oxygen species accumulation was assessed with confocal microscopy and light microscopy using ROS probes DCFH2-DA and TMB, respectively. NO was assayed using the NO probe DAF-2DA and confocal microscopy. Stigmas from various different angiosperms were found to accumulate ROS, predominantly H2O2, constitutively. In Senecio squalidus and Arabidopsis thaliana high amounts of ROS/H2O2 were localized to stigmatic papillae. ROS/H2O2 amounts appeared reduced in stigmatic papillae to which pollen grains had adhered. S. squalidus and A. thaliana pollen produced relatively high amounts of NO compared with stigmas; treating stigmas with NO resulted in reduced amounts of stigmatic ROS/H2O2. Constitutive accumulation of ROS/H2O2 appears to be a feature of angiosperm stigmas. This novel finding is discussed in terms of a possible role for stigmatic ROS/H2O2 and pollen-derived NO in pollen-stigma interactions and defence.

Arabidopsis↗
PubMed2002

A chemical perspective on the interplay between NO, reactive oxygen species, and reactive nitrogen oxide species.

Nitric oxide (nitrogen monoxide, NO) plays a veritable cornucopia of regulatory roles in normal physiology. In contrast, NO has also been implicated in the etiology and sequela of numerous neurodegenerative diseases that involve reactive oxygen species (ROS) and nitrogen oxide species (RNOS). In this setting, NO is often viewed solely as pathogenic; however, the chemistry of NO can also be a significant factor in lessening injury mediated by both ROS and RNOS. The relationship between NO and oxidation, nitrosation, and nitration reactions is summarized. The salient factors that determine whether NO promotes, abates, or interconnects these chemistries are emphasized. From this perspective of NO chemistry, the type, magnitude, location, and duration of either ROS or RNOS reactions may be predicted.

Antioxidants↗
PubMed2003

Species-specific usage of sleeping sites in two sympatric mouse lemur species (Microcebus murinus and M. ravelobensis) in northwestern Madagascar.

We investigated the sleeping site ecology of two sympatric mouse lemur species (Microcebus murinus and M. ravelobensis) in northwestern Madagascar during the second half of the dry season with respect to the type, quality, and usage pattern of the sleeping sites, as well as to social sleeping habits and response to potential threats. The type and quality of the sleeping sites differed between the two species. M. murinus used protected wooden shelters (tree holes) more frequently than M. ravelobensis, and M. ravelobensis used a broader variety of less protected sites (e.g., branches, lianas, and leaves) than M. murinus. Whereas male M. murinus usually slept alone, and female M. murinus mostly slept in groups, both sexes of M. ravelobensis slept in mixed-sex sleeping groups. M. murinus relied on crypsis in their sleeping sites, whereas M. ravelobensis regularly showed a flight response to the approach of an observer. This behavioral difference could indicate an adaptation to a higher predation risk in less protected sleeping sites. Whereas female M. murinus showed a high site fidelity, male M. murinus and both sexes of M. ravelobensis frequently changed their sleeping sites, which may also be interpreted as an antipredator strategy. The results are discussed with respect to three possible ecological explanations: interspecies competition, restricted resource availability, and niche differentiation. The latter is the most likely explanation for these interspecific differences.

Animals↗
PubMed1993

Species differences in nucleotide pool levels of 2',3'-dideoxycytidine: a possible explanation for species-specific toxicity.

The nucleoside analogue, 2',3'-dideoxycytidine (ddC), a potent inhibitor of human immunodeficiency virus reverse transcriptase (in its anabolized triphosphorylated form), mediates virologic and immunologic improvements in AIDS patients. Clinical studies using ddC have shown various ddC-related toxicities, the most pronounced being a dose-limiting peripheral neuropathy. The dose responsiveness and manifestation of the ddC-related neuropathy vary among species, with greatest sensitivity in human > monkey > rabbit whereas mice and rats are insensitive to ddC-related neuropathy. This study has examined nucleotide pool sizes of ddCTP and its constituents (ddC, ddCMP, ddCDP) in cultured fibroblasts (human, rabbit, mouse) and freshly isolated peripheral lymphocytes (monkey, rabbit, rat, and mouse). Cells were treated with 10 microM [3H]ddC and nucleotide pool sizes analyzed by HPLC. The formation of nucleotide pools increased during the 24-hr assay period. Fibroblast pool formation of phosphorylated metabolites was significantly greater in human > rabbit > mouse. Lymphocytes demonstrated a similar pattern with monkey > rabbit > mouse = rat. Total ddC anabolite pools were also found to be significantly smaller (p < 0.05) in rodent lymphocytes than in those of rabbit or monkey, and rodent fibroblasts were smaller than those of human or rabbit (p < 0.05). These findings indicate that nucleoside phosphorylation and intracellular levels of phosphorylated metabolites may play an important role in determining species sensitivity and manifestation of ddC-related toxicity.

Animals↗
PubMed1992

Comparative sensitivity of gametes and early developmental stages of a sea urchin species (Echinometra mathaei) and a bivalve species (Isognomon californicum) during metal exposures.

Bioassays were developed using sperm of a sea urchin (Echinometra mathaei), and sperm, embryos, and larvae of a bivalve species (Isognomon californicum). Sea urchin spawning was restricted to only a few months of the year and viability of sperm throughout the year varied from 5 to 75%. Sea urchin fertilization assays were affected by temporal variation in sperm viability. Spawning in this bivalve species occurs year-round and there is little temporal variation in sperm viability. Since stringent sperm:egg ratios are not required for the bivalve embryo and larval assays, these were less affected by variation in gamete quality. The relative sensitivity of the various assays were compared during exposure to three different metal pollutants: cadmium, copper, and tributyltin. Gametes and embryos were relatively resistant to cadmium toxicity, but larvae were very sensitive. With copper and tributyltin, sea urchin and bivalve fertilization assays were the least sensitive; and bivalve growth assays were the most sensitive, followed closely by the bivalve embryo assays. On the basis of sensitivity, ease and time required to conduct the assay, and salinity tolerance, the bivalve embryo assay was recommended as the overall single most reliable toxicity bioassay. However a multispecies, multidimensional approach using sperm fertilization assays as well as embryo assays should be employed, perhaps in a hierarchal manner. Larval growth assays were deemed too tedious and time consuming to be used routinely, but due to their high sensitivity, should still be considered as a valuable comparative tool.

Animals↗
PubMed1986

Immunohistochemical localization of urotensin I and other neuropeptides in the caudal neurosecretory system of three species of teleosts and two species of elasmobranchs.

In three species of teleosts - carp Cyprinus carpio; grass carp Ctenopharyngodon idella; and crucian carp Carassius auratus - the caudal neurosecretory system displays small, medium-sized and large neurons. Urotensin I (UI)-immunoreactive and UI-nonreactive neurons were found in all three groups; in general, the number of the latter neurons exceeded that of the former. Noteworthy are: (i) UI-immunoreactive fibers in the caudal spinal cord and (ii) dense accumulations of UI-immunoreactive product around the capillaries of the urophysis. In two species of elasmobranchs-cat shark Heterodontus japonicus and swell shark Cephaloscyllium umbratile - neurosecretory neurons decreased in size in rostro-caudal direction. Most of the neurosecretory perikarya, their axons and the corresponding neurohemal areas were UI-immunoreactive, but a small number of secretory neurons was devoid of immunoreaction. Oxytocin, arginine vasopressin, substance P, somatostatin, neurotensin, vasoactive intestinal polypeptide and gastrin-releasing peptide were not detected in the caudal neurosecretory system of the carp.

Animals↗
PubMed1988

A histochemical comparison of human corneal stromal glycoconjugates with eight other species. Distinct species-dictated differences in binding sites of Griffonia simplicifolia I.

Frozen sections of human, calf, rabbit, rat, cat, dog, goat, lamb, and hog corneas were stained with various lectins using an avidin-biotin-peroxidase complex to study glycoconjugates of stromal matrix. Staining of the stromal matrix and keratocytes with an alpha-galactose-specific lectin, Griffonia simplicifolia I (GSA-I) was species-dependent. The stromal matrices of cat, dog, and hog corneas invariably reacted intensely with this lectin, whereas those of the human, calf, rabbit, rat, and lamb did not react. A positive reaction with GSA-I could be abolished in each instance by preincubation of the sections with alpha-galactosidase. The stromal matrices and keratocytes of all nine species reacted positively with wheat germ agglutinin, concanavalin A, and Ricinus communis agglutinin but did not react with soybean agglutinin. Results of this study may help select an appropriate animal model for further investigate human corneal stromal glycoconjugates.

Animals↗
PubMed1977

Production of specific antibodies to contractile proteins, and their use in immunofluorescence microscopy. II. Species-specific and species-non-specific antibodies to smooth and striated chicken muscle actin.

The injection of rabbits with insoluble or soluble G-actin from chicken smooth or striated muscle will produce antibodies that are equally reactive, and species and tissue non-specific in immunoprecipitation, immunofluorescence and actin-activated Mg2+-ATPase inhibition tests. These antibodies have been used for the identification of actin-containing fibrils in a variety of tissues. When G-actins from chicken smooth or striated muscle are immobilized by chemical linkage to Affi-Gel 702 microbeads, their immunogenicity is increased, but the antibodies obtained against them are species-specific and will only react with actin and actin-containing structures from chicken and are therefore limited in use. It is concluded from this work that insoluble G-actin is the preferable immunogen to obtain precipitating antibodies for wide use.

Actins↗
PubMed2001

Characterization of a SINE species from vicuna and its distribution in animal species including the family Camelidae.

Twenty-six sequences of a short interspersed repetitive element (SINE) with a size of approximately 150 base pairs (bp) were isolated from the genomic DNA of Vicugna vicugna (vicuna). RNA polymerase III split promoter sequence was observed in most of them, and many had direct repeats flanking to SINEs as well as a poly(A)-like structure. The SINE sequences were designated as "vic-1" sequences. Comparison of the vic-1 consensus sequence with sequences registered in the DNA database (DDBJ/ EMBL/GENBANK) revealed that the vic-1 sequence had a 79% homology with mouse ala-tRNA gene. In addition, the tRNA-related region of the consensus sequence was folded into a cloverleaf structure as with mouse ala-tRNA. These findings strongly indicated that vic-1 was a retroposon derived from ala-tRNA gene. The vic-1 sequences were used as a probe for dot-blot hybridization to examine the distribution of their homologous sequences in the genomes of various animal species spanning 14 orders, of which, homologous sequences were found only in the Camelidae family. In order to examine the phylogenetical relationship among vicuna, llama, and camel, vic-1 insertion analysis and homology analysis of vic-1 sequences were performed at each locus. The analyses indicated that vic-1 sequences were generated in a common ancestor of the animal species, and that camels first branched off from the clade Camelidae, followed by vicunas and llamas.

Animals↗
PubMed1987

A DNA probe to distinguish the species Anopheles quadriannulatus from other species of the Anopheles gambiae complex.

DNA probes used previously to distinguish the species Anopheles gambiae sensu stricto, An.arabiensis, An.melas and An.merus were tested against An.quadriannulatus. Using these DNA probes, An.gambiae s.s. and An.quadriannulatus were indistinguishable. A genomic library was constructed for An.quadriannulatus. Differential screening of this genomic library with An.gambiae s.s. and An.quadriannulatus genomic DNAs identified a species-specific, repeated DNA sequence. When used as a hybridization probe, this DNA sequence clearly distinguished An.gambiae s.s. from An.quadriannulatus. A simplified protocol for the use of DNA probes is described which may be used to identify material squashed directly on to nitrocellulose filter paper.

Animals↗
PubMed1983

Differences in blood vessels between species: relation to differences in blood vessels of varying type within the same species.

1. Major differences in physiological and pharmacological responsiveness may be observed between blood vessels that differ either in anatomical type or in that they serve different organs or tissues. 2. The intrinsic properties of the vascular smooth muscle appears to differ little between species. No important differences in noradrenergic innervation have been observed, but major differences may exist in neural dilator systems. A few differences have been demonstrated that can be attributed to variations in the receptor population. No clear differences in local humoral mechanisms are known. There is, however, an insufficient number of strictly comparable studies in different species and it is likely that more differences will be found as our knowledge of vascular responsiveness is extended.

Animals↗
PubMed2004

Genetic diversity and biogeography of Cunninghamia konishii (Cupressaceae), an island species in Taiwan: a comparison with Cunninghamia lanceolata, a mainland species in China.

Luanta-fir (Cunninghamia konishii), an endemic to Taiwan, is an outcrossing, long-lived conifer. Populations of C. konishii are generally fragmented due to a once high intensity of timber exploitation. C. konishii and Cunninghamia lanceolata are two sibling taxa constituting derivative-progenitor species relationship. The amount of genetic variations within and between 11 and 10 populations of C. konishii and C. lanceolata, respectively, were assessed using amplified fragment length polymorphism (AFLP) markers in this report. Three AFLP primer pairs generated a total of 357 and 226 markers for C. konishii and C. lanceolata samples, of which 56.1 and 65.3% are polymorphic, respectively. Analysis of molecular variance indicates a 4.78% variation between C. konishii and C. lanceolata. A relatively high value of genetic variation (24.60%) was apportioned between the populations of C. konishii. In contrast, a lower divergence value (12.21%) between populations was found for C. lanceolata. The population with the highest genetic diversity was found in Nantou County, which concurred with the results of many other tree species investigated in Taiwan. The estimates of the number of migrants between populations (Nm), obtained from population pair-wise PhiST, suggest that gene flow in C. konishii is efficient in some adjacent populations but is restricted in the rest. Individual UPGMA tree, generated based on AFLP markers, suggests six evolutionary lineages for C. konishii. All evolutionary lineages of C. konishii were derived from C. lanceolata. In conclusion, the migration patterns of Cunninghamia from mainland China may have been established following multiple sources, migrant-pools, long-distance dispersal events, and via different directions.

Genetic Variation↗
PubMed2001

The effect of aliphatic, naphthenic, and aromatic hydrocarbons on production of reactive oxygen species and reactive nitrogen species in rat brain synaptosome fraction: the involvement of calcium, nitric oxide synthase, mitochondria, and phospholipase A.

This study investigated the effects of C7 and C9 aliphatic (n-heptane, n-nonane), naphthenic (methylcyclohexane, 1,2,4-trimethylcyclohexane (TMCH)) and aromatic (toluene, 1,2,4-trimethylbenzene (TMB)) hydrocarbons on the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in rat brain synaptosome fraction. Methyl mercury (MeHg) was included as a positive control. Exposure of the synaptosomes to the hydrocarbons produced a concentration-dependent linear increase in the formation of the fluorescence of 2',7'-dichlorofluorescein (DCF) as a measure of the production of ROS and RNS. Formation of RNS was demonstrated by preincubation of the synaptosome fraction with the neuronal nitric oxide synthase (nNOS) inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME), which reduced the MeHg and TMCH-stimulated fluorescence by 51% and 65%, respectively. The naphthenic hydrocarbon TMCH showed the strongest potential for ROS and RNS formation in rat brain synaptosomes, followed by TMB, toluene, n-nonane, n-heptane, and methylcyclohexane, respectively. TMCH was selected for mechanistic studies of the formation of ROS. Both MeHg and TMCH induced an increase in intracellular calcium concentration [Ca(2+)]i as measured with Fura-2. Blockade of voltage-dependent Ca(2+) channels with lanthanum prior to stimulation with MeHg and TMCH led to a reduction in the ROS/RNS formation of 72% and 70%, respectively. Furthermore, addition of cyclosporin A (CSA), a blocker of the mitochondrial permeability transition pore (MTP), lowered both the MeHg and TMCH-elevated DCF fluorescence by 72% and 59%. Preincubation of the synaptosome fraction with the protein tyrosine kinase inhibitor genistein lowered the MeHg and TMCH-stimulated fluorescence by 85% and 91%, respectively. Addition of the extracellular signal-regulated protein kinase (MEK)-1 and -2 inhibitor U0126 reduced the fluorescence stimulated by MeHg and TMCH by 62% and 63%. Furthermore, the protein kinase C inhibitor bisindolylmaleimide reduced the fluorescence stimulated by MeHg and TMCH by 52% and 56%. The compound 1-(6-[17beta-3-methoxyestra- 1,3,5(10)-trien- 17-yl]-aminohexyl)-1H-pyrrole-2,5-dione (U73122), which inhibits phospholipase C, was shown to decrease the ROS and RNS formation induced by MeHg and TMCH by 49% and 64%, respectively. The phospholipase A2 (PLA2) inhibitor 7,7-dimethyl eicosadienoic acid (DEDA) reduced fluorescence in response to MeHg and TMCH by 49% and 54%. Simultaneous addition of L-NAME, CSA, and DEDA to the synaptosome fraction totally abolished the DCF fluorescence. In conclusion, C7 and C9 aliphatic, naphthenic, and aromatic hydrocarbons stimulated formation of ROS and RNS in rat brain synaptosomes. The naphthenic hydrocarbon TMCH stimulated formation of ROS and RNS in the synaptosomes through Ca(2+)-dependent activation of PLA2 and nNOS, and through increased transition permeability of the MTP. Exposure of humans to the naphthenic hydrocarbon TMCH may stimulate formation of free radicals in the brain, which may be a key factor leading to neurotoxicity.

Alkanes↗
PubMed2003

Modelling biological invasions: species traits, species interactions, and habitat heterogeneity.

In this paper we explore the integration of different factors to understand, predict and control ecological invasions, through a general cellular automaton model especially developed. The model includes life history traits of several species in a modular structure interacting multiple cellular automata. We performed simulations using field values corresponding to the exotic Gleditsia triacanthos and native co-dominant trees in a montane area. Presence of G. triacanthos juvenile bank was a determinant condition for invasion success. Main parameters influencing invasion velocity were mean seed dispersal distance and minimum reproductive age. Seed production had a small influence on the invasion velocity. Velocities predicted by the model agreed well with estimations from field data. Values of population density predicted matched field values closely. The modular structure of the model, the explicit interaction between the invader and the native species, and the simplicity of parameters and transition rules are novel features of the model.

Computer Simulation↗
PubMed2002

Comparison of liver enzymes in osmerid fishes: key differences between a glycerol accumulating species, rainbow smelt (Osmerus mordax), and a species that does not accumulate glycerol, capelin (Mallotus villosus).

Activities of enzymes associated with glycerol synthesis were compared in the liver of two osmerid fishes, the smelt (Osmerus mordax), which can accumulate high (400 mM) levels of glycerol and capelin (Mallotus villosus) that does not accumulate glycerol. Animals were sampled at approximately the same time of year and temperature thus negating potential seasonal effects. These species are closely related, reducing interpretative issues involving comparison between unrelated species. We found that key enzyme activities were elevated in the smelt relative to the non-glycerol accumulating capelin, namely enzymes involved with glycolysis (phosphofructose kinase-1 and aldolase), amino acid metabolism (aspartate aminotransferase and alanine aminotransferase), gluconeogenesis (phosphoenolpyruvate carboxykinase) and glycerol synthesis (glycerol-3-phosphate dehydrogenase). The enzyme profiles strongly support the hypothesis that smelt can synthesize glycerol by utilizing glycogen and amino acids as the carbon source and that they have increased capacity for metabolic flux through loci required for synthesis of the three carbon intermediate dihydroxyacetone phosphate and subsequently glycerol synthesis.

Amino Acids↗
PubMed2002

Atherina punctata and Atherina lagunae (Pisces, Atherinidae), new species found in the Mediterranean sea. 2. Molecular investigations of three Atherinid species.

On the basis of morphoanatomical parameters, the sand smelt species (Atherina boyeri Risso, 1810) is viewed as a highly polymorphic complex. In this study, intraspecific sequence variation in a portion of the cytochrome b gene was examined in 88 individuals from Tunisia and France. The correlation between the results of statistical analysis of the sequence data using a variety of tree-building algorithms and morphoanatomical analyses demonstrated the subdivision into three putative species: A. boyeri, which only includes non-punctuated fishes, A. punctata, which corresponds to punctuated fishes and A. lagunae, which corresponds to atherines living in lagoons.

Algorithms↗