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931.
Measurement of vitellogenin,a biomarker for exposure to oestrogenic chemicals,in a wide variety of cyprinid fish 总被引:8,自引:0,他引:8
C. R. Tyler B. van der Eerden S. Jobling G. Panter J. P. Sumpter 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(7):418-426
There is increasing concern about man-made chemicals in the aquatic environment that mimic oestrogens because they may disrupt
reproductive function. Vitellogenin, a precursor of egg-yolk in fish and other oviparous animals, may be used as a biomarker
for “oestrogen” exposure. This study investigated the use of a radioimmunoassay developed to carp (Cyprinus carpio) vitellogenin to measure vitellogenin in other species of fish, especially cyprinids that would be of value for field and
laboratory studies on oestrogenic xenobiotics. Of the nine families of fish studied, only vitellogenin from cyprinids (to
which the carp belongs) showed good cross-reactivity in the carp vitellogenin radioimmunoassay. Vitellogenin from cyprinids
native to Europe that cross reacted in the carp vitellogenin radioimmunoassay included: bream (Abramis brama), roach (Rutilus rutilus), rudd (Scardinius erythropthalmus), gudgeon (Gobio gobio) and minnow (Phoxinus phoxinus). Vitellogenin from cyprinids used widely in ecotoxicology that cross reacted in the carp vitellogenin radioimmunoassay included:
fathead minnow (Pimephales promelas), zebrafish (Brachydanio rerio) and goldfish (Carassius auratus). In the cyprinids studies, the concentrations of vitellogenin in mature females were between a few hundred and a thousand
microgram per millilitre. Concentrations of plasma vitellogenin in immature females were always greater than 200 ng·m-1, whereas in males (with the exception of the fathead minnow) plasma vitellogenin concentrations were less than 20 ng·ml-1 (and generally, much lower). The results suggest that the structure of vitellogenin is highly conserved within the cyprinid
family and that the carp vitellogenin radioimmunoassay may be used to measure the concentrations of vitellogenin in plasma
from a wide variety of cyprinids. 相似文献
932.
Solveig Persson-Sjögren Sture Forsgren Pål Rooth Inge-Bert Täljedal 《Cell and tissue research》1996,284(3):391-400
Collagenase-isolated pancreatic islets from C57BL/6J mice were cultured overnight and transplanted under the kidney capsule of non-diabetic syngeneic hosts. Cryostat sections of grafts and fresh islets were stained for acetylcholinesterase (AChE) and vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI). Immediately after isolation, as well as 2-5 days after transplantation, VIP-LI- and AChE-positive nerve cell bodies were clearly seen in the periphery of the islets. Grafts 3-5 days old exhibited a transient and marked increase in VIP-LI nerve cell bodies and fibers. Seven days after transplantation VIP-LI nerve structures began to decrease in number and after 26-52 weeks they were no longer detectable. In contrast, AChE-positive nerve cell bodies and fibers, which showed a relatively constant pattern of distribution, were observed throughout the entire observation period. Restaining experiments demonstrated the coexistence of VIP-LI and AChE activity in the neurons. It is concluded that the grafts were extensively equipped with an intrinsic VIP-ergic and AChE-positive innervation. The initial, transient enhancement of VIP-LI expression probably reflects an adaptation of the neuro-insular complex to the preganglionic denervation, or to the ectopic environment, or both. 相似文献
933.
934.
Charles H. A. Snijders Rob A. Samson Ellen S. Hoekstra Thérèse Quellet J. David Miller Petra C. E. M. de Rooij-van der Goes A. J. M. Baar A. E. J. Dubois Henk F. Kauffman 《Mycopathologia》1996,135(2):119-128
In the European coastal dunes, marram grass (Ammophila arenaria) is planted in order to control sand erosion. In the years 1986 to 1991, workers on the Wadden islands in the Netherlands planting marram grass showed lesions of skin and mucous membranes, suggesting a toxic reaction. Fusarium culmorum dominated the mycoflora of those marram grass culms that were used for planting. This plant material had been cut and stored for more than one week in the open. The Fusarium toxin deoxynivalenol (DON) was detected in the suspect marram grass culms. Isolated F. culmorum strains were able to produce DON in vitro in liquid culture as well as in experimentally inoculated wheat heads. Pathogenicity tests, toxin test as well as RAPD analysis showed that the F. culmorum strains were not specialized for marram grass but may form part of the West-European F. culmorum population infecting cereals and grasses. Storage on old sand-dunes with plant debris may have led to the high occurrence of F. culmorum and contamination with DON. Marram grass culms should be obtained from young plantings on dunes on the seaward slopes and cut culms should not be stored. 相似文献
935.
The electric dichroism of alpha-chymotrypsin has been measured in a buffer containing 0.1 M Na(+), 10 mM Mg(2+) and 25 mM Tris-cacodylate pH 7.2. The reduced dichroism as a function of the electric field strength can be represented by the orientation function for permanent dipoles and is not consistent with the orientation function for induced dipoles. After correction for the internal directing field, the dipole moment is 1.1 x 10(-27) Cm (+/- 10%), corresponding to 340 D, at 20 degrees C. The assignment of the permanent dipole moment is confirmed by the shape of the dichroism rise curves, which require two exponentials with amplitudes of opposite sign for fitting. The dichroism decay time constants measured in the range of temperatures between 2 and 30 degrees C indicate a temperature induced change of the structure, which is equivalent to an increase of the hydrodynamic radius from r = 26.6 A at 2 degrees C to 28.5 A at 30 degrees C. Our results demonstrate that electrooptical investigations of proteins with a high time resolution can be extended to physiological salt concentrations without serious problems by use of appropriate instruments. 相似文献
936.
Gabriele Bierbaum Friedrich Götz Andreas Peschel Thomas Kupke Mart van de Kamp Hans-Georg Sahl 《Antonie van Leeuwenhoek》1996,69(2):119-127
Lantibiotics are antibiotic peptides that contain the rare thioether amino acids lanthionine and/or methyllanthionine. Epidermin, Pep5 and epilancin K7 are produced by Staphylococcus epidermidis whereas gallidermin (6L-epidermin) was isolated from the closely related species Staphylococcus gallinarum. The biosynthesis of all four lantibiotics proceeds from structural genes which code for prepeptides that are enzymatically modified to give the mature peptides. The genes involved in biosynthesis, processing, export etc. are found in gene clusters adjacent to the structural genes and code for transporters, immunity functions, regulatory proteins and the modification enzymes LanB, LanC and LanD, which catalyze the biosynthesis of the rare amino acids. LanB and LanC are responsible for the dehydration of the serine and threonine residues to give dehydroalanine and dehydrobutyrine and subsequent addition of cysteine SH-groups to the dehydro amino acids which results in the thioether rings. EpiD, the only LanD enzyme known so far, catalyzes the oxidative decarboxylation of the C-terminal cysteine of epidermin which gives the C-terminal S-aminovinylcysteine after addition of a dehydroalanine residue.Abbreviations Dha
2,3-didehydroalanine
- Dhb
2,3-didehydrobutyrine
- Lan
lanthionine
- Melan
methyllanthionine 相似文献
937.
Pretreatment of wheat straw using combined wet oxidation and alkaline hydrolysis resulting in convertible cellulose and hemicellulose 总被引:12,自引:0,他引:12
Bjerre AB Olesen AB Fernqvist T Plöger A Schmidt AS 《Biotechnology and bioengineering》1996,49(5):568-577
The wet oxidation process of wheat straw has been studied as a pretreatment method to attain our main goal: To break down cellulose to glucose enzymatic, and secondly, to dissolve hemicellulose (e.g., for fermentation) without producing microbial inhibitors. Wet oxidation combined with base addition readily oxidizes lignin from wheat straw facilitating the polysaccharides for enzymatic hydrolysis. By using a specially constructed autoclave system, the wet oxidation process was optimized with respect to both reaction time and temperature. The best conditions (20 g/L straw, 170 degrees C, 5 to 10 min) gave about 85% w/w yield of converting cellulose to glucose. The process water, containing dissolved hemicellulose and carboxylic acids, has proven to be a direct nutrient source for the fungus Aspergillus niger producing exo-beta-xylosidase. Furfural and hydroxymethyl-furfural, known inhibitors of microbial growth when other pretreatment systems have been applied, were not observed following the wet oxidation treatment. (c) 1996 John Wiley & Sons, Inc. 相似文献
938.
Kinetics of excited states of pigment clusters in solubilized light-harvesting complex II: photon density-dependent fluorescence yield and transmittance. 下载免费PDF全文
R Sch?del F Hillmann T Schr?tter J Voigt K D Irrgang G Renger 《Biophysical journal》1996,71(6):3370-3380
Relative fluorescence yield, phi F, and transmittance, T, were measured in solubilized light-harvesting complex II (LHCII) as a function of photon density, Ip, of monochromatic 645-nm laser pulses (duration: approximately 2.5 ns). Special efforts were made in constructing an optical set-up that allows the accurate determination of the fluorescence from an area of constant Ip, phi F(Ip) starts to decline at approximately 10(14) and drops to values below 0.01% at maximum Ip (approximately 10(19) photons cm-2 pulse-1). T(Ip) decreases only slightly at photon densities of approximately 10(15) but increases steeply at values of > 10(17) photons cm-2 pulse-1. The interpretation of the phi F(Ip) data using the saturation limit of Mauzerall's multiple hit model leads to a unit size of about 10-15 chlorophyll molecules. One interpretation is to attribute this result to a very fast exciton-exciton annihilation of multiple excited states generated within this small domain. Alternatively, based on the assumption that delocalized cluster states within the monomeric/trimeric subunit of LHCII exist, the results can be consistently described by a kinetic model comprising ground, monoexcitonic, and biexcitonic states of clusters and a triplet state that is quenched by carotenoids in LHCII. Within the framework of this model the annihilation of multiple excitations is explained as ultrafast radiationless relaxation of higher excited cluster states. Comparative measurements in diluted acetonic Chl a solution are consistently described by the depletion of the ground state, taking the absorption cross section at the used wavelength. 相似文献
939.
Sabine Kölle Fred Sinowatz Gudrun Boie Ines Totzauer Werner Amselgruber Johnna Plendl 《The Histochemical journal》1996,28(6):441-447
Summary The mRNA of the zona pellucida glycoprotein ZP3 was localized in frozen sections of pig ovaries, isolated oocytes and early embryos byin situ hybridization using biotinylated oligonucleotide probes. In follicles, the distribution of mRNA for ZP3 was correlated with the developmental stage: in primordial and primary follicles, the mRNA was shown to be predominantly localized in the oocyte. In secondary follicles, mRNA was found in both the oocyte and follicle cells. In tertiary and preovulatory follicles, the follicle cells showed distinct staining, whereas the oocyte was labelled weakly. In the early embryo, i.e. 2 days after fertilization, mRNA for ZP3 could not be demonstrated. Our results suggest that, in the pig, the zona pellucida protein ZP3 is synthesized by the oocyte and the follicle cells in sequence. After fertilization, synthesis of ZP3 is terminated. 相似文献
940.
The karyotype of male and female Hemilepistus elongatus was investigated by means of C-banding. The diploid chromosome number in both sexes is 2n = 50. By scrutinizing general morphology and localization of the constitutive heterochromatin, no heteromorphic sex chromosomes were found. All chromosome pairs in males are well paired during diakinesis. Hybridization of genomic DNA with (GACA)4 and (GATA)4 oligonucleotides revealed no sex-specific patterns. Key words : karyotype, C-banding, sex determination, simple DNA-repeats, Isopoda. 相似文献