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2.
Bioaccessibility measurements have the potential to improve the accuracy of risk assessments and reduce the potential costs of remediation when they reveal that the solubility of chemicals in a matrix (e.g., soil) differs markedly from that in the critical toxicity study (i.e., the key study from which a toxicological or toxicity reference value is derived). We aimed to apply this approach to a brownfield site contaminated with chromium, and found that the speciation was CrIII, using a combination of alkaline digestion/diphenylcarbazide complexation and X-ray absorption near edge structure analysis. The bioaccessibility of Cr2O3, the compound on which a reference dose for CrIII is based, was substantially lower (<0.1%) than that of the CrIII in the soils, which was a maximum of 9%, giving relative bioaccessibility values of 13,000% in soil. This shows that the reference dose is based on essentially an insoluble compound, and thus we suggest that other compounds be considered for toxicity testing and derivation of reference dose. Two possibilities are CrCl3·6H2O and KCr(SO4)2·12H2O, which have been used for derivation of ecological toxicity reference values and are soluble at a range of dosing levels in our bioaccessibility tests. 相似文献
3.
Mirjam Frischknecht Vidhya Jagannathan Philippe Plattet Markus Neuditschko Heidi Signer-Hasler Iris Bachmann Alicja Pacholewska Cord Dr?gemüller Elisabeth Dietschi Christine Flury Stefan Rieder Tosso Leeb 《PloS one》2015,10(10)
The identification of quantitative trait loci (QTL) such as height and their underlying causative variants is still challenging and often requires large sample sizes. In humans hundreds of loci with small effects control the heritable portion of height variability. In domestic animals, typically only a few loci with comparatively large effects explain a major fraction of the heritability. We investigated height at withers in Shetland ponies and mapped a QTL to ECA 6 by genome-wide association (GWAS) using a small cohort of only 48 animals and the Illumina equine SNP70 BeadChip. Fine-mapping revealed a shared haplotype block of 793 kb in small Shetland ponies. The HMGA2 gene, known to be associated with height in horses and many other species, was located in the associated haplotype. After closing a gap in the equine reference genome we identified a non-synonymous variant in the first exon of HMGA2 in small Shetland ponies. The variant was predicted to affect the functionally important first AT-hook DNA binding domain of the HMGA2 protein (c.83G>A; p.G28E). We assessed the functional impact and found impaired DNA binding of a peptide with the mutant sequence in an electrophoretic mobility shift assay. This suggests that the HMGA2 variant also affects DNA binding in vivo and thus leads to reduced growth and a smaller stature in Shetland ponies. The identified HMGA2 variant also segregates in several other pony breeds but was not found in regular-sized horse breeds. We therefore conclude that we identified a quantitative trait nucleotide for height in horses. 相似文献
4.
d-Aspartate in Human Brain 总被引:3,自引:3,他引:0
Eugene H. Man George H. Fisher Iris L. Payan Rodolfo Cadilla-Perezrios Nancy M. Garcia Radhika Chemburkar Georgine Arends William H. Frey II 《Journal of neurochemistry》1987,48(2):510-515
The presence of the biologically uncommon D-aspartic acid (D-aspartate) in human brain white matter has been previously reported. The earlier study has now been expanded to include D/L-aspartate ratios from 67 normal brains. The data show that the D-aspartate content increases rapidly from 1 year to approximately 35 years of age, levels off in middle age, and then appears to decrease somewhat. The D-aspartate content in gray matter remains at a consistently low level (half of that found in white matter) throughout the human life span. Within the limitations of current analytical methods, there was no detectable difference in D/L-aspartate ratios in white and gray matter of brains with Alzheimer's disease and several other pathologies when compared with brains of normal subjects. However, the presence of a significant D-aspartate level in white matter during the adult life span may lead to changes in protein configuration related to dysfunctions associated with the aging brain. 相似文献
5.
Iris Maldener Wolfgang Lockau Yuping Cai C. Peter Wolk 《Molecular & general genetics : MGG》1991,225(1):113-120
Summary It has been suggested that a calcium-dependent intracellular protease of the cyanobacterium, Anabaena sp., participates in the differentiation of heterocysts, cells that are specialized for fixation of N2. Clones of the structural gene (designated prcA) for this protease from Anabaena variabilis strain ATCC 29413 and Anabaena sp. strain PCC 7120 were identified via their expression in Escherichia coli. The prcA gene from A. variabilis was sequenced. The genes of both strains, mutated by insertion of a drug resistance cassette, were returned to these same strains of Anabaena on suicide plasmids. The method of sacB-mediated positive selection for double recombinants was used to achieve replacement of the wild-type prcA genes by the mutated forms. The resulting mutants, which lacked Ca2+-dependent protease activity, were not impaired in heterocyst formation and grew on N2 as sole nitrogen source. 相似文献
6.
Summary Aerobic spore-forming bacteria were isolated from plant tissue cultures from a commercial plant cultivation station. Bacillus circulans was found to be a detrimental infectant as a serious consequence of the heat-resistance of the endospores of these bacteria. They were extremely motile, utilized several growth-promoting factors, and could be eliminated by early microscopical identification, killing by heat treatment, or by using antibiotics or disinfecants.Dedicated to Professor Dr. Gustav Kortüm on the occasion of his 80th birthday 相似文献
7.
B Kempter J Markl M Brenowitz C Bonaventura J Bonaventura 《Biological chemistry Hoppe-Seyler》1985,366(1):77-86
The hemocyanins of the horseshoe crab Limulus polyphemus (48-mer), the tarantula Eurypelma californicum (24-mer), and the lycosid spider Cupiennius salei (dodecamer, hexamer) were dissociated into subunits, the subunits isolated and studied by two-dimensional immunoelectrophoresis for interspecific cross-reactivities. Among the subunits a to g of Eurypelma on the one side, and I to VI of Limulus on the other, a number of cross-reactions were obtained which agree with the topologic subunit positions in the published models of quaternary structure: a = II, b-c = V-VI, d = IV, e = I, f = IIIb, g = IIIa (IIa). However, cross-reactivity was only strong in the following combinations: a/II, d/IV, b-c/V-VI (the monomers of the two heterodimers could not be correlated individually). A rather weak cross-reaction was obtained in the case of e/I and g/IIIa (IIa); a cross-reaction between f and IIIb was almost undetectable. On the other hand, f/IV clearly cross-reacted, and so did e/IIIa (IIa), which apparently is not in agreement with the two models of quaternary structure. These unexpected relationships, however, indicate the possible phylogeny of the subunits. Antiserum against Cupiennius hemocyanin precipitated subunit f of Eurypelma and subunit IV of Limulus and, moreover, revealed common antigen determinants present on these subunits. Denaturation of hemocyanin subunits of the three species with 8M urea yielded a completely different immunological behavior in that in all intra- and interspecific combinations the reaction of immunological identity was obtained. The published models of quaternary structure and a possible subunit phylogeny of cheliceratan hemocyanins is discussed in view of the present results and the results of the preceding paper. [Markl, J. et al. (1984) Hoppe-Seyler's Z. Physiol. Chem. 365, 619-631.] 相似文献
8.
We have isolated adenovirus origins of DNA replication from both the right and left ends of the genome, which are functional on linear autonomously replicating mini-chromosomes. The mini-chromosomes contain two cloned inverted adenovirus termini and require non-defective adenovirus as a helper. Replicated molecules are covalently attached to protein, and DNA synthesis is initiated at the correct nucleotide even when the origins are not located at molecular ends. The activity of embedded origins leads to the generation of linear minichromosomes from circular or linear molecules. These observations therefore suggest that sequences within the adenovirus origin of replication position the protein priming event at the adenovirus terminus. Experiments investigating the regeneration of deleted viral inverted terminal repeat sequences show a sequence-independent requirement for inverted sequences in this process. This result strongly suggests that repair results from the formation of a panhandle structure by a displaced single strand. On the basis of these observations we propose a model for the generation of adenovirus mini-chromosomes from larger molecules. 相似文献
9.
Summary The distribution and characterization of the opioid octapeptide met5-enkephalin-arg6-gly7-leu8 (met5-enk-arg6-gly7-leu8) within the gastrointestinal tract of the rat has been determined by immunohistochemistry and radioimmunoassay by use of a newly developed antibody to met5-enk-arg6-gly7-leu8. With both techniques, met5-enk-arg6-gly7-leu8-immunoreactivity (met5-enk-arg6-gly7-leu8IR) was detected in all regions of the gastrointestinal (GI) tract except the esophagus. The highest concentration of immunoreactive met5-enk-arg6-gly7-leu8 was observed in the colon, while intermediate concentrations were found in the stomach, duodenum, jejunum, and ileum. Immunostained somata were observed chiefly in the myenteric plexus; immunostained processes were present primarily in the myenteric plexus and the circular muscle layer. This distribution pattern is similar to that previously observed with antiserum to met5-enkephalin-arg6-phe7 (met5-enk-arg6phe7). Chromatographic analysis of met5-enk-arg6-gly7leu8-immunoreactive peptides extracted from the GI tract revealed the presence of an immunoreactive peptide of high molecular weight which accounted for approximately three-quarters of met5-enk-arg6-gly7-leu8-IR in both stomach and colon. These findings suggest a role for peptides related to the octapeptide met5-enk-arg6-gly7-leu8 in the regulation of GI function. 相似文献
10.
Iris D. Zellmer 《Hydrobiologia》1996,319(2):87-92
UV-B (290 nm) tolerance of Daphnia pulex, conditioned to four different food levels (Chlorophyta), was tested under standardized conditions with an artificial radiation source. Parameters measured were survival, percentage of egg bearing Daphnia and the number of juveniles produced after irradiation. UV-B tolerance of Daphnia pulex was found to be significantly improved with increasing food concentrations at all three parameters. The impact of the four different food concentrations on the photoreactivation system was tested with simultanous UV-B and white-light irradiation of Daphnia. Survival rate improved significantly with increasing food levels compared to solely UV-B irradiation. Photoreactivation had no effect on the reproductive parameters. 相似文献