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61.
The mycotoxin aflatoxin M1 (AfM1) is a serious food safety hazard for which the European Commission has already established a maximum permissible level of 0.05 μg/kg AfM1 in milk and products thereof. For control analysis laboratories are increasingly asked to submit full uncertainties of their analytical results.The evaluation of measurement uncertainties of an analytical method for the determination of AfM1 in milk and milk powder on the basis of ‘in-house’ validation data in compliance with the ‘Guide to the Expression of Uncertainty in Measurement (GUM)’ [1] and the ‘EURACHEM Guide’ [2] is described. A similar approach will be used to assess the performance of methods employed by laboratories participating in the certification of reference materials for AfM1 in milk powder. 相似文献
62.
1. Many fish stocks have declined, because of overharvesting, habitat destruction and introduced species. Despite efforts to rehabilitate some of these stocks, not all are responding or are recovering only slowly. 2. In freshwater systems, introduced crayfish are often problematic, and it has been suggested that their egg predation could reduce recruitment in depleted stocks of native fish. 3. Here, we report the results of a field experiment, using experimental cages, on the extent of predation on eggs of great Arctic charr (Salvelinus umbla) in Lake Vättern, Europe’s fifth largest lake. Here, the great Arctic charr has declined dramatically and is listed as critically endangered. 4. We were able to partition the total loss rate of eggs into background mortality, predation by introduced signal crayfish (Pacifastacus leniusculus) and predation by native fish. The mortality rate of charr eggs because of crayfish was estimated at more than five times that because of native fish. Of the total loss of eggs, 80% is believed to be caused by crayfish and 14% by fish, with 6% being natural background mortality. 5. In a worst case scenario, our data infer that only 25% of the original number of eggs would survive, compared with 75% in the absence of crayfish. This could impair recovery of the stock of the endangered great Arctic charr in Lake Vättern. 6. Contrary to earlier claims that crayfish predation on eggs of great Arctic charr is insignificant, our results indicate that crayfish predation may exceed fish predation and suggest that the abundance of signal crayfish on the spawning sites of great Arctic charr should be managed. 相似文献
63.
64.
Abstract A multidisciplinary field study investigating the fate and transport of petroleum hydrocarbons commonly associated with jet-fuel contamination is currently underway at Columbus Air Force Base (AFB), Mississippi. Sixty sediment cores from 12 boreholes were recovered from the study aquifer. The goal of this initial sampling was to characterize the potential microbial activity using 14C-labeled substrates, as well as the presence, abundance, and distribution of specific hydrocarbon degrading genotypes using DNA:DNA hybridization. Enumeration of total microbial abundance using a 16S rDNA universal oligonucleotide probe was compared to traditional enumeration methods. Total culturable populations determined by spread plate analysis ranged from a low of 10(4) to more than 10(6) organisms per gram sediment. Microbial abundance estimated by DNA hybridization studies with 16S rDNA genes ranged from 10(7) to 10(8) organisms per gram sediment. Molecular analysis of aquifer samples using DNA probes targeting genes encoding the degradative enzymes alkane hydroxylase (alkB), catechol 2,3-dioxygenase (nahH), naphthalene dioxygenase (nahA), toluene dioxygenase (todC1C2), toluene monooxygenase (tomA), and xylene monooxygenase (xylA), as well as two probes measuring methanogenic microorganisms, codh (carbon monoxide dehydrogenase) and mcr (methyl coenzyme reductase), revealed that each target gene sequence was present in nearly all 60 samples. The presence of organisms demonstrating the phenotype to degrade BTEX and naphthalene was further supported using mineralization assays with 14C-labeled benzene, toluene, naphthalene, and phenanthrene. Minimal activity occurred during the first 24 hours. After a period of 5-7 days, greater than 40% of the target compounds were mineralized in aquifer sediments. 相似文献
65.
ASHG activities relative to education: Human genetics as a component of medical school curricula: A report to the American society of human genetics 总被引:1,自引:7,他引:1 下载免费PDF全文
In recent years, there has been a remarkable increase in both the rate of acquiring new information about human genetics and the importance of human genetics for modern health care. As a result, human genetics educators have queried whether the teaching of human genetics in North-American medical schools has kept pace with these increases. To address this question, a survey of these medical schools was undertaken to assess how human geneticists perceive the teaching of human genetics in their respective institutions. The results of the survey, begun and completed in 1985, indicate the following: (1) the teaching of human genetics in medical schools is extremely variable from one institution to another, with some schools having no identifiable human genetics teaching at all; (2) the relevance of human genetics to other basic science and clinical disciplines apparently leads to noncategorical or fragmented teaching of human genetics, which may also contribute to the absence of a specific medical school course in the subject; and (3) there is a need for closer collaboration between human genetics educators and their respective medical school administrators and curriculum committees. 相似文献
66.
Kerstin Brinkmann Paul Waring Stefan P Glaser Verena Wimmer Denny L Cottle Ming Shen Tham Duong Nhu Lachlan Whitehead Alex RD Delbridge Guillaume Lessene Ian M Smyth Marco J Herold Gemma L Kelly Stephanie Grabow Andreas Strasser 《The EMBO journal》2020,39(24)
Studies of gene‐targeted mice identified the roles of the different pro‐survival BCL‐2 proteins during embryogenesis. However, little is known about the role(s) of these proteins in adults in response to cytotoxic stresses, such as treatment with anti‐cancer agents. We investigated the role of BCL‐XL in adult mice using a strategy where prior bone marrow transplantation allowed for loss of BCL‐XL exclusively in non‐hematopoietic tissues to prevent anemia caused by BCL‐XL deficiency in erythroid cells. Unexpectedly, the combination of total body γ‐irradiation (TBI) and genetic loss of Bcl‐x caused secondary anemia resulting from chronic renal failure due to apoptosis of renal tubular epithelium with secondary obstructive nephropathy. These findings identify a critical protective role of BCL‐XL in the adult kidney and inform on the use of BCL‐XL inhibitors in combination with DNA damage‐inducing drugs for cancer therapy. Encouragingly, the combination of DNA damage‐inducing anti‐cancer therapy plus a BCL‐XL inhibitor could be tolerated in mice, at least when applied sequentially. 相似文献
67.
Microfilaments and tropomyosin of cultured mammalian cells: isolation and characterization 总被引:4,自引:3,他引:4 下载免费PDF全文
Microfilaments were isolated from cultured mammalian cells, utilizing procedures similar to those for isolation of "native" thin filaments from muscle. Isolated microfilaments from rat embryo, baby hamster kidney (BHK- 21), and Swiss mouse 3T3 cells appeared structurally similar to muscle thin filaments, exhibiting long, 6 nm Diam profiles with a beaded, helical substructure. An arrowhead pattern was observed after reaction of isolated microfilaments with rabbit skeletal muscle myosin subfragment 1. Under appropriate conditions, isolated microfilaments will aggregate into a form that resembles microfilament bundles seen in situ cultured cells. Isolated microfilaments represent a complex of proteins including actin. Some of these components have been tentatively identified, based on coelectrophoresis with purified proteins, as myosin, tropomyosin, and a high molecular weight actin-binding protein. The tropomyosin components of isolated microfilaments were unexpected; polypeptides comigrated on SDS-polyacrylamide gels with both muscle and nonmuscle types of tropomyosin. In order to identify more specifically these subunits, we isolated and partially characterized tropomyosin from three cell types. BHK-21 cell tropomyosin was similar to other nonmuscle tropomyosins, as judged by several criteria. However, tropomyosin isolated from rate embryo and 3T3 cells contained subunits that comigrated with both skeletal muscle and nonmuscle types of myosin, whereas the BHK cell protein consistently contained a minor muscle-like subunit. The array of tropomyosin subunits present in a cell culture was reflected in the polypeptide chain pattern seen on SDS-polyacrylamide gels of microfilaments isolated from that culture. These studies provide a starting point for correlating changes in the ultrastructural organization of microfilaments with alterations in their protein composition. 相似文献
68.
ORSOLYA SZOKOLÓCZI RICHÁRD SCHWAB ISTVÁN PETÁK LÁSZLÓ ÖRFI ÁKOS PAP ALEX N. EBERLE 《Journal of receptor and signal transduction research》2013,33(4-6):217-235
TT-232 is a structural analogue of somatostatin exhibiting strong and selective growth-inhibitory effects, inhibition of neurogenic inflammation, as well as general anti-inflammatory and analgesic potential without the wide-ranging endocrine side effects of the parent hormone and its “traditional” analogues. The anti-inflammatory action of TT-232 is mediated through the SSTR4 receptor, and its antitumor activity is mediated through the SSTR1 receptor and by the tumor-specific isoform of pyruvate kinase. Its mechanism of action is in line with a new era of molecular medicine called signal transduction therapy, where “false” intracellular or intercellular communication is inhibited or corrected without interfering with basic cell functions and machinery. TT232 has passed phase I clinical trials without toxicity and significant side effects, and phase II studies are running for oncological and anti-inflammatory indications, respectively. This compound has the perspective to become the first drug in molecularly targeted therapy of inflammation where a combined effect of anti-inflammatory, analgesic, and neurogenic inflammation-inhibiting activity can be achieved. 相似文献
69.
The acidic glycolipid fraction (AF) of the porcine, parasitic nematode,
Ascaris suum , consisted of two subfractions. The major component AF II
reacted with orcinol-sulfuric acid and molybdate, while the minor component
AF I gave a positive reaction with azure-A, a cationic dye specific for
sulfatides. Sugar constituent analysis, methanolysis, methylation analysis,
matrix-assisted laser desorption/ionization time- of-flight mass
spectrometry, liquid secondary-ion mass spectrometry, and gas-liquid
chromatography/mass spectrometry specified AF II to be an unusual
phosphoinositolglycosphingolipid (Galalpha1-Ins-P-1ceramide) and the minor
component AF I to be a 3-sulfogalactosylcerebroside (HSO3-
3Galss1-1ceramide). The ceramide moiety of both components consisted of
lignoceric (C24:0) and cerebronic (C24h:0) acids and mainly C17 iso-
branched sphingosine. Immunohistochemical localization studies of the
glycolipid-bound antigenic determinants with a polyclonal antiserum against
AF II and an anti-sulfatide monoclonal antibody against AF I revealed the
presence of the AF II-epitope in the intestine, whereas the AF I-epitope
was found in the hypodermis, contractile zone of somatic muscle cells and
the external musculature of the uterus. To our knowledge, this is the first
report of the presence of a sulfatide in an invertebrate.
相似文献
70.
Molecular cloning and characterization of an alpha1,3 fucosyltransferase, CEFT-1, from Caenorhabditis elegans 总被引:1,自引:1,他引:1
We report on the identification, molecular cloning, and characterization of
an alpha1,3 fucosyltransferase (alpha1,3FT) expressed by the nematode,
Caenorhabditis elegans . Although C. elegans glycoconjugates do not express
the Lewis x antigen Galbeta1-- >4[Fucalpha1-->3]GlcNAcbeta-->R,
detergent extracts of adult C.elegans contain an alpha1,3FT that can
fucosylate both nonsialylated and sialylated acceptor glycans to generate
the Lexand sialyl Lexantigens, as well as the lacdiNAc-containing acceptor
GalNAcbeta1-->4GlcNAcbeta1-- >R to generate GalNAcbeta1-->4
[Fucalpha1-->3]GlcNAcbeta1-->R. A search of the C.elegans genome
database revealed the existence of a gene with 20-23% overall identity to
all five cloned human alpha1,3FTs. The putative cDNA for the C.elegans
alpha1,3FT (CEFT-1) was amplified by PCR from a cDNA lambdaZAP library,
cloned, and sequenced. COS7 cells transiently transfected with cDNA
encoding CEFT-1 express the Lex, but not sLexantigen. The CEFT-1 in the
transfected cell extracts can synthesize Lex, but not sialyl Lex, using
exogenous acceptors. A second fucosyltransferase activity was detected in
extracts of C. elegans that transfers Fuc in alpha1,2 linkage to Gal
specifically on type-1 chains. The discovery of alpha-fucosyltransferases
in C. elegans opens the possibility of using this well-characterized
nematode as a model system for studying the role of fucosylated glycans in
the development and survival of C.elegans and possibly other helminths.
相似文献