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31.
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K S Yeung M Hoare N F Thornhill T Williams J D Vaghjiani 《Biotechnology and bioengineering》1999,63(6):684-693
This article describes the calibration of a spectroscopic scanning instrument for the measurement of selected contaminants in a complex biological process stream. Its use is for the monitoring of a process in which contaminants are to be removed selectively by flocculation from yeast cell homogenate. The main contaminants are cell debris, protein, and RNA. A low-cost instrument has been developed for sensitivity in the region of the NIR spectrum (from 1900 to 2500 nm) where preliminary work found NIR signatures from cell debris, protein, and RNA. Calibration models have been derived using a multivariate method for concentrations of these contaminants, such as would be found after the flocculation process. Two strategies were compared for calibrating the NIR instrument. In one case, samples were prepared by adding materials representative of the contaminants to clarified yeast homogenate so the contaminant levels were well known but outside the range of interest. In the other case, where samples were like those from the process stream after flocculation and floc removal, there was uncertainty of analysis of contaminant level, but the calibration was in the range of interest. Calibration using process stream samples gave results close to those derived from traditional assays. When the calibration models were used to predict the contaminant concentrations in previously unseen samples, the correlation coefficients between measurements and predictions were above 90% in all cases but one. The prediction errors were similar to the errors in the traditional assays. 相似文献
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Harder David B.; Capeless Christopher G.; Maggio John C.; Boughter John D. Jr; Gannon Kimberley S.; Whitney Glayde; Azen Edwin A. 《Chemical senses》1992,17(4):391-401
Mice have been characterized as either tasters or non-tastersof the bitter compound sucrose octa-acetate(SOA). However, 11of 17 supposedly non-taster inbred strains were found to avoid1 mM SOA. All 17 strains were indifferent to 0.1 mM SOA. Tasterstrains avoided both concentrations. The intermediate phenotypewas dubbed demitaster. A consistent phenotypic dominance orderwas found in crosses among both inbred and outbred strains (taster> non-taster > demitaster). Demitasters were found (withtasters) in an outbred strain showing monogenic segregationfor SOA avoidance. This, plus monogenic segregation in a back-crossof taster to demitaster inbred strains, suggested a third alleleat the Soa locus (Soac). Demitaster allelism was supported bythe strong associations found in 15 strains between the threeSOA phenotypes and HindIII restriction fragment patterns forthe closely linked Prp (proline rich protein) loci. SOA demitasterstrains were also intermediate in raffinose undeca-acetate (RUA)avoidance. Furthermore, B6.SW-Soa2 congenic mice avoided notonly SOA, but RUA and eight other acetylated sugars. A previouslyproposed separate RUA-sensitivity gene (Rua) thus appeared tobe redundant. 相似文献
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James E. Boggan Julian T. Hoff Edwin B. Boldrey William M. Wara 《The Western journal of medicine》1980,133(2):108-114
Thirty cases of intraspinal neoplasms occurring during the first two decades of life are reviewed. Histologic examination showed 13 of these to be astrocytomas, 6 neuroblastomas, 5 sarcomas, 3 ependymomas, 2 neurofibromas and 1 a schwannoma. Orthopedic deformities developed or worsened in 60 percent of patients surviving longer than a year after diagnosis. In five patients some form of endocrine deficiency developed after irradiation. For treatment of radiosensitive extradural malignant lesions, biopsy followed by irradiation is advocated. 相似文献
39.
David G. Reid David M. Doddrell Dudley H. Williams Keith R. Fox 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,798(1):111-114
Uniformly 15N-labelled triostin A and echinomycin have been prepared by growing the producing organisms on enriched media and their 15N nuclear magnetic resonance spectra partially assigned by a combination of nuclear Overhauser effect and scalar coupling constant measurements. Selective feeding experiments using unlabelled L-tryptophan-supplemented media have shown that N-1 and N-4 of the quinoxaline rings have their origins in the indole and amino groups of tryptophan, respectively. 相似文献
40.
The role of duplication in the expression of a variable surface glycoprotein gene of Trypanosoma brucei 总被引:1,自引:0,他引:1
The variable surface glycoprotein (VSG) genes of Trypanosoma brucei have been classified into two groups depending upon whether or not duplication of the genes is observed when they are expressed. We report here the observation of duplication apparently linked to expression of the ILTaT 1.3 gene in the ETaR 1 trypanosome stock. In the ILTaR 1 stock, expression of the ILTaT 1.3 VSG did not involve a new duplication, but instead activation of a preexisting gene copy that had been apparently generated earlier by a duplication event analogous to that directly observed in the ETaR 1 trypanosomes. The results suggest that the well-characterised gene duplications found with other VSG genes are common to all VSG genes but are not directly responsible for controlling expression. All currently available data can be accommodated by a model that assumes that gene duplication and replacement occurs independently of antigenic switching. 相似文献