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At least 523 records · Page 29Linked to original sources
PubMed2003

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation by silica in inflammation and fibrosis.

Exposure to particulate silica (most crystalline polymorphs) causes a persistent inflammation sustained by the release of oxidants in the alveolar space. Reactive oxygen species (ROS), which include hydroxyl radical, superoxide anion, hydrogen peroxide, and singlet oxygen, are generated not only at the particle surface, but also by phagocytic cells attempting to digest the silica particle. Two distinct kinds of surface centers-silica-based surface radicals and poorly coordinated iron ions-generate O(2)(*)(-) and HO(*) in aqueous solution via different mechanisms. Crystalline silica is also a potent stimulant of the respiratory burst in phagocytic cells with increased oxygen consumption and production of O(*)(-), H(2)O(2), and NO leading to acute inflammation and HO(*) generation in the lung. Oxidative stress elicited by crystalline silica is also evidenced by increased expression of antioxidant enzymes such as manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase, and the enzyme inducible nitric oxide synthase (iNOS). Generation of oxidants by crystalline silica particles and by silica-activated cells results in cell and lung injury, activation of cell signaling pathways to include MAPK/ERK kinase (MEK), and extracellular signal-regulated kinase (ERK) phosphorylation, increased expression of inflammatory cytokines (e.g., tumor necrosis factoralpha [TNFalpha], interleukin-1 [IL-1]), and activation of specific transcription factors (e.g., NFkappaB, AP-1). Silica can also initiate apoptosis in response to oxygen- and nitrogen-based free radicals, leading to mitochondrial dysfunction, increased gene expression of death receptors, and/or their ligands (TNFalpha, Fas ligand [FasL]).

Animals↗
PubMed1998

Hemopexin from four species inhibits the association of heme with cultured hepatoma cells or primary rat hepatocytes exhibiting a small number of species specific hemopexin receptors.

Hemopexin (Hx) binds heme with a very high affinity (Kd<0.1 pmol/L). It has been implicated as a major vehicle for the transport of heme into liver cells, involving a receptor-mediated recycling mechanism. However, previous studies indicated that heme is not taken up by cultured embryonic chick or adult rat hepatocytes by such a mechanism, because heme added as heme hemopexin failed to affect heme-responsive activities of 5-aminolevulinic acid synthase and heme oxygenase. Here, we investigated the importance of hemopexin in hepatic heme uptake in cultured rat hepatocytes and human HepG2 hepatoma cells, and determined the number and species specificity of hemopexin receptors on the rat hepatocytes. We also tested whether there is a difference between heterologous and homologous hemopexins. We found the following: 1) heme is inhibited from associating with hepatocytes by apo hemopexins from rat, human, rabbit, and chicken; 2) heme readily associates with hepatocytes when heme hemopexin preparations are added in which the ratio of heme to hemopexin exceeds 1.0; 3) heme induces heme oxygenase mRNA in rat hepatocytes and this induction is prevented by excess hemopexin; and 4) rat hepatocytes exhibit only about 2,000 hemopexin receptors per cell when using rat hemopexin, and none when using hemopexin of rabbit and human. We conclude that hemopexin plays a limited role in heme uptake by cultured hepatocytes and hepatoma cells, and that heme which exceeds the hemopexin binding capacity is taken up directly from heme-albumin.

Animals↗
PubMed1995

Modeling response of species to microcontaminants: comparative ecotoxicology by (sub)lethal body burdens as a function of species size and partition ratio of chemicals.

A model was designed and calibrated with accumulation data to calculate the internal concentrations of microcontaminants in organisms as a function of a few constants and variables. The main factors are the exposure time, the external exposure concentration, the partition ratio of the compound, and the size of the taxon concerned. The model was applied to calculate the lethal and sublethal body burdens of several priority compounds and some major taxa. Estimations were generally confirmed at the order of magnitude level by measured residues and applied doses if available. According to the estimations, most priority compounds chosen were critical for most taxa above internal concentrations of 0.1 mmol.kg-1 wet wt. Trichloromethane, 1,2,4-trichlorobenzene, and hexachlorobenzene were lethal above this level only, whereas other organic microcontaminants affected at least some taxa at lower body burdens. The log(Kow) of the organic compounds ranged from 2.0 to 7.0. Keeping in mind that bioconcentration and -magnification ratios for metals may be quite variable, the lowest critical residues estimated were just below the value of 0.1 mmol.kg-1 wet wt. Here, external concentrations encountered in natural habitats seem to be a promising tool for predictive comparative ecotoxicology. The critical body burdens for plants and invertebrates may have been overestimated due to uncertainty about the parameters. Among the different taxa, however, the fish families chosen (Salmonidae and Cyprinidae) seem to be most sensitive to most compounds. Internal response concentrations of the herbicide atrazine were the lowest in micro- and macrophytes, whereas parathion affected invertebrates at low levels. The database that provided the external response concentrations was also consulted to estimate so-called extrapolation or safety factors. On average, long-term no effect concentrations in water are estimated to be about 10-30 times below short-term median lethal levels. In general, short-term versus long-term, lethal versus sublethal, and median versus no response concentration ratios each contributed factors of about 2-3 to this overall ratio. The model for internal concentrations indicated that the ratio between the short-term and the long-term LC50 will be high for large species and high octanol-water partition ratios.

1-Octanol↗
PubMed1990

Characterization of molecular species of liver microsomal carboxylesterases of several animal species and humans.

Seven carboxylesterase isozymes were purified to electrophoretic homogeneity from liver microsomes of mouse, hamster, guinea pig, rabbit, and monkey by the same procedure used previously to obtain three isozymes from the rat, and their physical, enzymological, and immunological properties were compared with those of the rat isozymes. The substrate specificity and immunological reactivity of liver microsomal carboxylesterases from pig, cow, beagle dog, and human were also examined for comparison, though these enzymes were not purified. The ten purified preparations have similar subunit weight (57,000-64,000), but their isoelectric points differ widely (4.7-6.5). The purification procedure of all isozymes included concanavalin A-Sepharose column chromatography. The isozymes were not eluted from the column with a high concentration of sodium chloride, but were efficiently eluted with alpha-methylmannoside. This observation suggested that the carboxylesterases studied are glycoproteins. All the isozymes except rat RL1 and RL2 possess a high hydrolytic activity toward all the substrates examined. Long-chain monoglyceride was hydrolyzed by the purified carboxylesterase isozymes. Anti-rat RH1 immunoglobulin G was found to possess high cross-reactivity with all isozymes tested, except monkey MK2, by immunoblotting analysis. The amino acid compositions of carboxylesterase isozymes showed considerable similarities, except for monkey MK2. The amino-terminal amino acid sequences showed a striking homology, except for monkey MK2, though the amino-terminal amino acid itself was different in every isozyme. Hepatic microsomal carboxylesterases in mammals play an important role in drug and lipid metabolism in the endoplasmic reticulum, and it is noteworthy that the isozymes from various species examined here showed considerable similarities in physical, enzymatic, and immunochemical properties.

Amino Acid Sequence↗
PubMed2004

AFLP analysis of Fusarium species in the section Sporotrichiella-evidence for Fusarium langsethiae as a new species.

Amplified fragment length polymorphism (AFLP) was applied to compare 100 isolates of Fusarium poae, Fusarium sporotrichioides, and Fusarium langsethiae. Comparison of fingerprints revealed several markers specific for each group of isolates. Cluster analysis showed a clear separation of F. poae from F. sporotrichioides and F. langsethiae. F. langsethiae isolates formed a rather homogeneous group separated from F. sporotrichioides. The AFLP data obtained support F. langsethiae as a new Fusarium species, for the time being in the section Sporotrichiella.

Cluster Analysis↗
PubMed2004

Reactive oxygen species generation and peroxidase activity during Oidium neolycopersici infection on Lycopersicon species.

Histochemical and biochemical study of plant tissue responses were carried out on three Lycopersicon spp. accessions differing in response to Oidium neolycopersici. High production of superoxide anion was observed mainly in infected leaves of highly susceptible Lycopersicon esculentum cv. 'Amateur' during the first hours post inoculation (hpi). The production of hydrogen peroxide as well as an increase of peroxidase (POX) activity were detected mainly in resistant accessions at 4-12 hpi. A signal confirming the presence of very active POX was found in the apical part of tubes of germinating fungus and inside dead conidia. Increased soluble POX and catalase activity in leaf extracts of resistant accessions L. chmielewskii (LA 2663) and L. hirsutum (LA 2128) (20 hpi) correlated with the percentage of dead cells in infection sites. The correlation between production of reactive oxygen species (ROS) and activity of enzymes participating in their metabolism and hypersensitive response was evident during plant defence response.

Ascomycota↗
PubMedDate not supplied

Increased potential for NAD(P)H-dependent reactive oxygen species production of hepatic subcellular fractions of fish species with in vivo exposure to contaminants.

The present study investigated the proposed involvement of contaminant-stimulated reactive oxygen species (ROS) production in disease processes in fish. NAD(P)H-dependent ROS production of subcellular fractions was determined by the iron/EDTA-mediated oxidation of 2-keto-4-methiolbutyric acid. Hepatic cytosolic NADPH-dependent and microsomal NAD(P)H-dependent ROS production were increased 51-160% (P < 0.05) in rainbow trout (Oncorhynchus mykiss) 15 weeks after a single i.p. injection of polychlorobiphenyl (PCB) (100 mg Clophen A50 kg-1 wet wt.). Hepatic microsomal NADH-dependent ROS production was 114% higher in perch (Perca fluviatilis) from PCB-contaminated Lake Järnsjön compared to clean Lake Vänern, Sweden. Hepatic mitochondrial NADH-dependent, cytosolic NADH-dependent and microsomal NADPH-dependent ROS production were variously elevated up to 160% in flounder (Platichthys flesus) at various sites along two pollution transects near to the ports of Rotterdam and Amsterdam, Netherlands. Overall the data indicate increased potential for ROS production in liver of fish exposed to field pollution, and support the hypothesis of oxidative stress as a mechanism of contaminant-mediated disease in fish.

Animals↗
PubMed2003

Application of species-specific polymerase chain reaction in the forensic identification of tiger species.

Globally, tigers are considered to be endangered, and are listed on Appendix I of CITES. A simple test, using a species-specific primer pair, was developed to identify tiger meat, faeces and dried skin, and provide forensic evidence of illegal wildlife trade. The specific fragment of mitochondrial cytochrome b gene was also successfully amplified from raw DNA products extracted from single tiger hairs. This PCR-based approach opens a new avenue to forensic identification of less-than-optimal samples.

Animals↗
PubMed2002

Atherina punctata and Atherina lagunae (Pisces, Atherinidae), new species in the Mediterranean Sea. 1. Biometric investigations of three Atherinid species.

Discriminative canonical analysis of 87 biometric parameters in the marine and lagoon atherinids of 'Atherina boyeri' complex from the Mediterranean Sea helps defining three distinct atherinid groups: marine punctuated, marine unpunctuated and lagoon atherinids. Each atherinid group constitutes a clearly independent original entity. Besides, each one is a more or less heterogeneous group with geographical disparities, characterising specimen collected from France and Tunisia. Concordance of biometric, biochemical and genetic results as well help define two new species of atherinids: Atherina punctata = punctuated marine atherinids, and Atherina lagunae = atherinids living in lagoon environments.

Animals↗
PubMed1994

Genetic variation in the triploids of Japanese Fasciola species, and relationships with other species in the genus.

Twelve enzymes (encoded by 14 loci) in liver flukes of Fasciola species originating from Japan (parthenogenetic triploids), Korea (parthenogenetic diploids), the United States of America (USA) and Australia (all sexual diploids) were analysed using starch gel electrophoresis. Variation in electrophoretic patterns between samples was detected at fic enzyme loci (Ak, Got, Gpi, 6-Pgd and Pgm-2). Japanese worms (31, of which six were established as uniparental laboratory strains), which reproduce by parthenogenesis, exhibited three different isozyme patterns. This indicates that triploidy has arisen more than once in Japanese flukes. Japanese Fasciola sp. can be separated into three types on morphological grounds. For the six laboratory strains of Japanese worms, the parental morphological type was known. Each of the three isozyme patterns observed was restricted to one morphological type. Most alleles detected in the Japanese triploids were also found in diploid worms from the other countries: the only alleles not represented elsewhere were four at the Got locus and two at the Pgm locus. Flukes from a laboratory strain derived from a single Korean diploid worm resembled the Japanese worms in genotype more closely than did America (seven uniparental laboratory strains) or Australian (30 worms) specimens. Worms from the last two countries were closely related.

Animals↗
PubMed1980

Development of species identification in ducklings: VI. Specific embryonic experience required to maintain species-typical perception in ducklings.

Earlier results showed that highly specific responsiveness to the mallard maternal call at the species-typical repetition rate (around 4 notes/sec) develops in the embryo in advance of auditory experience. If the embryo continues to be deprived of normally occurring auditory experience (exposure to its own and/or sib vocalizations), the repetition-rate specificity is lost after hatching. The present results show that the embryo must be exposed to the embryonic contact-contentment call at the normal rate of 4 notes/sec in order to maintain the specific responsiveness to the maternal call at 4 notes/sec after hatching. Exposure to other rates of the embryonic call neither maintains nor modifies the 4 notes/sec specififity. Thus, the maintenance of seemingly innate postnatal behavioral development is dependent upon a highly specific, normally occurring prior experience; it will not be maintained if only rath er general (nonspecific) sensory-stimulative conditions prevail during ontogeny, as has been assumed in the past.

Age Factors↗
PubMed2003

Apoptosis induction by interleukin-2-activated cytotoxic lymphocytes in a squamous cell carcinoma cell line and Daudi cells - involvement of reactive oxygen species-dependent cytochrome c and reactive oxygen species-independent apoptosis-inducing factors.

Investigation of the induction of apoptosis by cytotoxic lymphocytes has mainly focused on the signalling associated with Fas and its adaptor proteins. The signal pathway via mitochondria, however, has not been sufficiently elucidated in cytotoxic lymphocyte-induced apoptosis. We examined the release of mitochondrial proapoptotic factors by lymphokine-activated killer (LAK) cells in two cell lines. LAK cell-induced DNA fragmentation of the target cells was suppressed to approximately 50% of control levels by the addition of neutralizing monoclonal antibody to Fas and a granzyme B inhibitor. When intracellular reactive oxygen species (ROS) were scavenged, the LAK cell-induced DNA fragmentation was decreased to approximately 60% of the non-treated cell level. Co-cultivation of Daudi cells with LAK cells increased cytosolic and mitochondrial ROS levels. Activation of procaspase-3 and apoptosis by treatment of oral squamous cell carcinoma cells (OSC) with LAK cells was partially inhibited by pretreatment of OSC cells with ROS scavengers and mitochondrial complex inhibitors. Furthermore, cytochrome c and apoptosis-inducing factor (AIF) were released from mitochondria by OSC cell treatment with supernatants of LAK cells. The supernatant-induced cytochrome c release was suppressed by mitochondrial complex inhibitors, but the inhibitors did not inhibit the release of AIF. These results indicate that LAK cells induce target cell apoptosis via not only the Fas/Fas ligand system and granzyme B, but also ROS-dependent cytochrome c and ROS-independent AIF release.

Apoptosis↗
PubMed2005

Cross-species investigation of Helicoverpa armigera microsatellites as potential markers for other related species in the Helicoverpa--Heliothis complex.

Primers previously designed to amplify microsatellite DNA markers in the Old World bollworm, Helicoverpa armigera, larvae were tested in three closely related species: the corn earworm, Helicoverpa zea, tobacco budworm, Heliothis virescens, and Heliothis subflexa. Of the fourteen loci surveyed, only four loci (HaB60, HaC14, HaC87, HarSSR1) consistently demonstrated scorable single-copy microsatellite bands. Of these four, length polymorphism was identified only in the HaB60 marker (160 bp, 140 bp) of the H. virescens and H. subflexa sampled laboratory populations. Partial DNA sequences of all the identified single-copy microsatellites are presented as well as alignments to their respective H. armigera microsatellite.

Animals↗
PubMed1997

Cloning and sequencing of a species-specific nucleotide fragment of Borrelia burgdorferi sensu stricto, which is repeated in several plasmids of the species.

Among the etiological agents of Lyme disease, Borrelia burgdorferi sensu stricto strains carry a 16 kb plasmid, which did not hybridize to plasmids of B. garinii and B. afzelii strains. A 1271 bp DNA fragment of the 16 kb plasmid was cloned. It hybridized to several plasmids of this species (16, 27 and 55 kb). Sequencing of the cloned insert revealed a 327 bp ORF coding for a 14 kDa protein of unknown function, which could be expressed in E. coli. This ORF, conserved among B. burgdorferi sensu stricto strains, was carried by the same three plasmids.

Amino Acid Sequence↗
PubMed1987

Strain and species identification by restriction fragment length polymorphisms in the ribosomal DNA repeat of Candida species.

Restriction fragment length polymorphisms in the ribosomal DNA (rDNA) have been shown to be a useful criterion for distinguishing among various isolates of Candida albicans. In a sample of 12 clinical isolates, we found six different classes based on variations in the fragments produced from genomic DNA by EcoRI and visualized after Southern transfer by being probed with a plasmid containing Saccharomyces cerevisiae rDNA. Some of the classes appeared to be heterozygous at the rDNA locus. Similar digestion of other Candida species showed that each could be identified on the basis of its restriction patterns. Since these are highly reiterated genes, the differences were apparent on ethidium bromide-stained gels; Southern transfers were not necessary. EcoRI restriction maps of the rDNA of C. albicans, C. stellatoidea, C. tropicalis, and C. guilliermondii were determined.

Candida↗
PubMed1988

Evolution of alpha-fetoprotein: sequence comparisons among AFP species and with albumin species.

Alpha-fetoprotein (AFP) and albumin are related proteins, which contain about 585 amino acid residues that are organized in a characteristic structure of 3 homologous domains of about 195 amino acid residues. We have compared the domains of mouse, rat, and human AFP and rat, bovine, and human albumin using computer programs designed to quantify relationships between proteins. The comparisons of corresponding domains of the AFPs (e.g. domain I of rat and human AFP) reveal that each domain is well conserved. Similar results were found for the comparisons of corresponding domains in the albumins. In contrast, there was much less similarity between corresponding domains of albumin and AFP. These comparisons between AFP and albumin revealed that: (1) the amino acid sequences in domain III, which is at their carboxy terminus, are most conserved, and (2) the amino acid sequences in domain I, which is at their amino terminus, are least conserved. This suggests that there are differences in the constraints on amino acid substitutions among the domains of AFP and albumin during the approximately 400 million years since they diverged from a common ancestor. Also, computer studies revealed that there are substantial differences between domains I, II, and III in each AFP and albumin species, which indicates that these domains are significantly different from their approximately 195 residue ancestral domain. Finally, we find that mouse and rat AFP are more dissimilar to the albumins than is human AFP. Overall, our computer analyses indicate that AFP and albumin can be considered to be composed of distinct, but related, approximately 195 residue proteins, each of which could differ in some of their properties; for example, the binding of fatty acids.

Amino Acid Sequence↗
PubMed2006

Protein-protein interactions more conserved within species than across species.

Experimental high-throughput studies of protein-protein interactions are beginning to provide enough data for comprehensive computational studies. Today, about ten large data sets, each with thousands of interacting pairs, coarsely sample the interactions in fly, human, worm, and yeast. Another about 55,000 pairs of interacting proteins have been identified by more careful, detailed biochemical experiments. Most interactions are experimentally observed in prokaryotes and simple eukaryotes; very few interactions are observed in higher eukaryotes such as mammals. It is commonly assumed that pathways in mammals can be inferred through homology to model organisms, e.g. the experimental observation that two yeast proteins interact is transferred to infer that the two corresponding proteins in human also interact. Two pairs for which the interaction is conserved are often described as interologs. The goal of this investigation was a large-scale comprehensive analysis of such inferences, i.e. of the evolutionary conservation of interologs. Here, we introduced a novel score for measuring the overlap between protein-protein interaction data sets. This measure appeared to reflect the overall quality of the data and was the basis for our two surprising results from our large-scale analysis. Firstly, homology-based inferences of physical protein-protein interactions appeared far less successful than expected. In fact, such inferences were accurate only for extremely high levels of sequence similarity. Secondly, and most surprisingly, the identification of interacting partners through sequence similarity was significantly more reliable for protein pairs within the same organism than for pairs between species. Our analysis underlined that the discrepancies between different datasets are large, even when using the same type of experiment on the same organism. This reality considerably constrains the power of homology-based transfer of interactions. In particular, the experimental probing of interactions in distant model organisms has to be undertaken with some caution. More comprehensive images of protein-protein networks will require the combination of many high-throughput methods, including in silico inferences and predictions. http://www.rostlab.org/results/2006/ppi_homology/

Animals↗