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41.
Three experiments were carried out to examine the consequences of concurrent infections with Ascaridia galli and Escherichia coli in chickens raised for table egg production. Characteristic pathological lesions including airsacculitis, peritonitis and/or polyserositis were seen in all groups infected with E. coli. Furthermore, a trend for increased mortality rates was observed in groups infected with both organisms which, however, could not be confirmed statistically. The mean worm burden was significantly lower in combined infection groups compared to groups infected only with A. galli. It was also shown that combined infections of E. coli and A. galli had an added significant negative impact on weight gain. 相似文献
42.
Thomas Galewski Marie-ka Tilak Sophie Sanchez Pascale Chevret Emmanuel Paradis Emmanuel JP Douzery 《BMC evolutionary biology》2006,6(1):80-17
Background
Mitochondrial and nuclear genes have generally been employed for different purposes in molecular systematics, the former to resolve relationships within recently evolved groups and the latter to investigate phylogenies at a deeper level. In the case of rapid and recent evolutionary radiations, mitochondrial genes like cytochrome b (CYB) are often inefficient for resolving phylogenetic relationships. One of the best examples is illustrated by Arvicolinae rodents (Rodentia; Muridae), the most impressive mammalian radiation of the Northern Hemisphere which produced voles, lemmings and muskrats. Here, we compare the relative contribution of a nuclear marker – the exon 10 of the growth hormone receptor (GHR) gene – to the one of the mitochondrial CYB for inferring phylogenetic relationships among the major lineages of arvicoline rodents. 相似文献43.
44.
L.A Verbrugge J.P Giesy D.A Verbrugge B.R Woodin J.J Stegeman 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2001,130(1):67-83
Induction of cytochrome P450 1A (CYP1A) can be used as a biomarker of exposure to planar halogenated aromatic hydrocarbons (PHAHs). Our objective was to characterize the induction of CYP1A activity and protein in three avian species following in vivo treatment with β-naphthoflavone (BNF) and/or isosafrole. Alkoxyresorufin-O-dealkylase (alk-ROD) activities of hepatic microsomes from Herring Gulls (Larus argentatus) (HGs), Double-crested Cormorants (Phalacrocorax auritus) (DCCs) and chickens (Gallus domesticus) were measured using ethoxy-, methoxy-, pentoxy- and benzyloxy-resorufin, in the presence and absence of the inhibitors ellipticine or furafylline. Immunoreactivity of microsomal proteins with antibodies to several CYP1A proteins was investigated. CYP1A protein and alk-ROD activities of HGs and DCCs, but not chickens, were induced by isosafrole. Ellipticine was a potent and non-selective inhibitor of alk-ROD activity in all three species, while furafylline inhibition of alk-ROD activities varied among species and treatments. In all three species, BNF induced a protein immunoreactive with monoclonal antibody to CYP1A1 from the marine fish Stenotomus chrysops (scup), but a CYP1A2-like protein was not detected in avian microsomes probed with polyclonal antibodies to mouse CYP1A2. Variations in responses among avian species indicate that CYP1A proteins and substrate specificities should be characterized for each species used in PHAH biomonitoring programs. 相似文献
45.
Previously, treatment of Tamm-Horsfall glycoprotein (THp) from different
donors with endo-beta-galactosidase has been shown to liberate a tetra- and
a Sd(a)-active pentasaccharide, concluding the presence of N-linked
carbohydrate chains containing additional N - acetyllactosamine units.
These type of oligosaccharides were not found in a detailed structure
elucidation of the carbohydrate moiety of THp of one male donor, suggesting
a donor-specific feature for these type of structures. Therefore, THp was
isolated from four healthy male donors and each subjected to
endo-beta-galactosidase treatment in order to release these tetra- and
Sd(a)-active pentasaccharide. Differences were observed in the total amount
of released tetra- and Sda-active pentasaccharide of the used donors (42,
470, 478, 718 microg/100 mg THp), indicating that the presence of repeating
N-acetyllactosamine units incorporated into the N-glycan moiety of THp is
donor specific. Furthermore, a higher expression of the Sd(a) determinant
on antennae which display N-acetyllactosamine elongation was observed,
suggesting a better accessibility for the
beta-N-acetylgalactosaminyltransferase. In order to characterize the
N-glycans containing repeating N- acetyllactosamine units, carbohydrate
chains were enzymatically released from THp and isolated. The
tetraantennary fraction, which accounts for more than 33% of the total
carbohydrate moiety of THp, was used to isolate oligosaccharides containing
additional N - acetyllactosamine units. Five N-linked tetraantennary
oligosaccharides containing a repeating N-acetyllactosamine unit were
identified, varying from structures bearing four Sd(a) determinants to
structures containing no Sd(a) determinant (see below). One compound was
used in order to specify the branch location of the additional N-
acetyllactosamine unit, and it appeared that only the Gal-6' and Gal-8'
residues were occupied by a repeating N -acetyllactosamine unit.
相似文献
46.
The demonstration that interleukin 2 (IL-2) is a lectin specific for
oligomannosides allows to understand a new function for this cytokine: as a
bifunctional molecule when bound to its receptor ss, IL-2 associates the
latter which the CD3/TCR complex, interacting with oligosaccharides of CD3
through its carbohydrate-recognition domain (Zanetta et al. , 1996,
Biochem. J., 318, 49-53). This induces the tyrosine phosphorylation of the
IL-2R beta by ++p56(lck) , the first step of the IL-2-dependent signaling.
Since this specific association is disrupted in vitro by oligomannosides
with five and six mannose residues, we made the hypothesis that pathogenic
cells or microorganisms could bind IL-2, consequently disturbing the IL-2-
dependent response. This study shows that the pathogenic yeast Candida
albicans (in contrast with nonpathogenic yeasts) binds high amounts of IL-2
as did cancer cells. In contrast with cancer cells, yeasts do not bind the
Man6GlcNAc2-specific lectin CSL, an endogenous "amplifier of activation
signals" (Zanetta et al. , 1995, Biochem. J., 311, 629-636).
相似文献
47.
48.
Robert E. Foley James R. Spotila John P. Giesy Carolyn H. Wall 《Environmental Biology of Fishes》1978,3(4):361-367
Synopsis Arsenic persists in Chautauqua Lake, New York waters 13 years after cessation of herbicide (sodium arsenite) application and continues to cycle within the lake. Arsenic concentrations in lake water ranged from 22.4–114.81 g l–1, = 49.0 ag l–1. Well water samples generally contained less than 10 g l–1 arsenic. Arsenic concentrations in lake water exceeded U.S. Public Health Service recommended maximum concentrations (10 g l–1) and many samples exceeded the maximum permissible limit (50 g l–1). Fish accumulated arsenic from water but did not magnify it. Fish to water arsenic ratios ranged from 0.4–41.6. Black crappie (Pomoxis nigromaculatus) contained the highest arsenic concentrations (0.14–2.04 g g–1 ), X = 0.7 g g–1) while perch (Perca flavescens), muskellunge (Esox masquinongy) and largemouth bass (Micropterus salmoides) contained the lowest concentrations (0.02–0.13 g g–1). Arsenic concentrations in fish do not appear to pose a health hazard for human consumers. 相似文献
49.
50.
Bakker BM Overkamp KM van Maris AJ Kötter P Luttik MA van Dijken JP Pronk JT 《FEMS microbiology reviews》2001,25(1):15-37
In Saccharomyces cerevisiae, reduction of NAD(+) to NADH occurs in dissimilatory as well as in assimilatory reactions. This review discusses mechanisms for reoxidation of NADH in this yeast, with special emphasis on the metabolic compartmentation that occurs as a consequence of the impermeability of the mitochondrial inner membrane for NADH and NAD(+). At least five mechanisms of NADH reoxidation exist in S. cerevisiae. These are: (1) alcoholic fermentation; (2) glycerol production; (3) respiration of cytosolic NADH via external mitochondrial NADH dehydrogenases; (4) respiration of cytosolic NADH via the glycerol-3-phosphate shuttle; and (5) oxidation of intramitochondrial NADH via a mitochondrial 'internal' NADH dehydrogenase. Furthermore, in vivo evidence indicates that NADH redox equivalents can be shuttled across the mitochondrial inner membrane by an ethanol-acetaldehyde shuttle. Several other redox-shuttle mechanisms might occur in S. cerevisiae, including a malate-oxaloacetate shuttle, a malate-aspartate shuttle and a malate-pyruvate shuttle. Although key enzymes and transporters for these shuttles are present, there is as yet no consistent evidence for their in vivo activity. Activity of several other shuttles, including the malate-citrate and fatty acid shuttles, can be ruled out based on the absence of key enzymes or transporters. Quantitative physiological analysis of defined mutants has been important in identifying several parallel pathways for reoxidation of cytosolic and intramitochondrial NADH. The major challenge that lies ahead is to elucidate the physiological function of parallel pathways for NADH oxidation in wild-type cells, both under steady-state and transient-state conditions. This requires the development of techniques for accurate measurement of intracellular metabolite concentrations in separate metabolic compartments. 相似文献