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41.
An informative family, in which parents shared HLA-Dw and Ia-like DRw (Ly-Li) antigens, was used to produce PLTs between members either phenoidentical for both Dw and DRw determinants or incompatible for Dw specificities only. These PLTs were restimulated by members of the family: two PLTs, although in DRw identity, reacted against members of the family bearing one maternal (c) and/or one paternal (a) haplotype. A third PLT also developed in DRw identity reacted with members bearing the other maternal (d) haplotype. Population studies with one of these PLTs did not show any correlation with Dw or DRw specificities. Family studies are in keeping, but do not demonstrate an HLA linkage. The data suggest that, along with the stimulating products (PLA) identical or closely related to the DRw determinants, other stimulating products (PLB), also probably HLA-linked, exist. Furthermore, one of the PLTs was produced without a primary MLR. 相似文献
42.
Two glucoamylases (I and II) were produced during solid-state culture of Aspergillus hennebergi (A. niger group) on cassava meal, whereas one glucoamylase and one alpha-amylase were synthesized by the mould in liquid culture. These glucoamylases were acidic proteins with thermotolerant activities. Glucoamylase I was not a glycoprotein, but glucoamylase II and the glucoamylase from liquid cultures contained 15% of sugars. The alpha-amylase was significantly less thermotolerant and of smaller molecular weight. The influence of culture conditions on the production of different amylases by the same Aspergillus strain on the same substrate is discussed. 相似文献
43.
Polymer motion in solution can be studied by 13CNMR relaxation methods, which provide information about the correlation time for C-H vectors. 13C-Relaxation and Nuclear Overhauser Enhancement (NOE) data may frequently be combined to determine the dipole-dipole relaxation contribution. An alternative method is proposed based on a comparison of the proton spin-lattice relaxation rates of the centre proton resonances of an unlabelled molecule with the relaxation rates of the 13C satellites (from 13C labelled molecules).Selectively labelled nigeran which is an alternating has been investigated. The discussion in terms of the occurrence of different motions for each of the two units of the polymer requires an unambiguous assignment of the two anomeric carbons. For this reason a detailed assignment of the 1H and 13C Nuclear Magnetic Resonance (NMR) spectra of nigeran in dimethylsulphoxide-d6 is described, based on T1 and NOE measurements in addition to selective homonuclear and heteronuclear spin decoupling experiments. These values are correlated with a conformation estimated by HSEA hard-spheres calculation. The measurements of the relaxation parameters for labelled and unlabelled compounds which provide an alternative determination of the 13C-1H dipole-dipole relaxation contribution in a macromolecule agree well with 13C-{1H} NOE experiments. 相似文献
44.
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Summary Papain was able to catalyze the one-step synthesis of Gly-Gly-PheNH2, from N-unprotected amino acid derivatives. Maximum synthetic activity was obtained for a pH value of 6.5 and for a ]PheNH2]/[Gly-GlyOEt] ratio of 6. The presence of an organic cosolvent, such as ethylene glycol, influenced the synthetic activity. Synthetic yield was higher than 65% for a 12.5 M cosolvent concentration. 相似文献
46.
Arques Didier G.; Michel Christian J.; Orieux Karine 《Bioinformatics (Oxford, England)》1992,8(1):5-14
The software AGE (Analysis of Gene Evolution) has been developedboth to study a genetic reality, i. e. the identification ofstatistical properties in genes (e.g. periodicities), and tosimulate this observed genetic reality, by models of molecularevolution. AGE has two types of models: (i) models of sequencecreation from oligonucleotides: concatenation model in seriesof an oligonucleotide, independent (or Markov) mixing modelof oligonucleotides according to given probabilities (or a Markovmatrix); (ii) models of sequence evolution from created sequences:insertion/deletion process of (mono, di, tri)nucleot-ides, basemutation process. The study of a reality and the developmentof simulation models are based on several new algorithms: approximatedsimulation and exact calculus to compute various autocorrelationfunctions, Fourier transformation of autocorrelation curves,recognition of a curve form, etc. AGE is implemented on IBMor compatible microcomputers and can be used by biologists withoutany computer knowledge to identify statistical properties intheir newly determined DNA sequence and to explain them by modelsof molecular evolution. 相似文献
47.
A four-year study showed a clear seasonal succession of species within the cladoceran community of the large, oligotrophic Sainte-Croix reservoir (S.E. France). Diaphanosoma brachyurum and Ceriodaphnia pulchella were strictly limited to the warm stratified period (July to October), whereas Bosmina longirostris and Bosmina coregoni were dominant during spring and autumn. Daphnia longispina was the only species to occur throughout the year with higher densities in spring.In spring and late autumn, the discharge of the inflowing river Verdon was high and the abundance of all species showed a gradient over the whole lake with lower densities close to the inflow. During the stratified period, water inflow was very low and species showed different patterns. Densities of the small form Ceriodaphnia pulchella were similar all along the long axis of the lake, whereas Daphnia densities were significantly higher near the dam. The distribution pattern of Diaphanosoma, an intermediate-sized species, showed similar trends to that of Daphnia. The only planktivorous fish in the pelagic zone, the bleak (Alburnus alburnus), fed mostly on large-bodied species (> 1.0 mm) and was more abundant close to the inflow current. A comparison between the length frequency distributions of cladocera upstream and downstream provided a clear demonstration of the effects of size-selective predation on prey populations. Finally, the interactions between spatial heterogeneity and long-term development of the zooplankton community and the indirect effects of predation are discussed. 相似文献
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49.
Selective, double irradiation allows the assignment of most 13C-n.m.r. signals in a series of per-O-acetyl disaccharides composed of two D-glucose residues linked α-(1→3), β-(1→3), α-(1→4), β-(1→4), α-(1→6), β-(1→6), and α,α-(1→1). The main influences that affect the chemical shifts are discussed and the spectra of β-cellobiose octaacetate and β-maltose octaacetate are compared to those of cellulose and amylose triacetate, respectively, to show the possibilities and limitations of a disaccharide model for the interpretation of the 13C-spectrum of a polymer. 相似文献
50.