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T Faraggiana D Villari J Jagirdar J Patil 《The journal of histochemistry and cytochemistry》1986,34(6):811-816
Lung alveoli are coated by a thin layer of extracellular material rich in anionic charges. The nature of this acid layer and its relationship to the phospholipid surfactant are not known. We investigated the possible presence of sialic acid groups by light and electron microscopy in tissues from normal fetal and adult lungs, using neuraminidase treatment followed by staining with the galactose-binding lectin from peanut, labeled with peroxidase. Our results showed that adult lung does not bear peanut lectin-reactive sites but that a very thin and distinct reactive layer becomes evident after neuraminidase treatment, especially on type II pneumocytes. In fetal lung, the entire surface of the developing respiratory tree is outlined by a strongly peanut lectin-reactive layer even if neuraminidase digestion is not performed. We conclude that the acid coat of the alveolar lining is in part composed of sialic acid residues and that sialic acid is added to the fetal lung as the alveoli mature. 相似文献
3.
A child with normal growth and development and the abnormal karyotype 46,XY,17ps, was analyzed using molecular probes localized to 17p13. The results indicated the presence of two copies of the probes YNZ22.1 (D17S5) and YNH37.3 (D17S28), previously shown to be deleted in all Miller-Dieker (MDS) patients studied. However, the patient was hemizygous for probe p144D6 (D17S34), which is absent in approximately 75% of the MDS patients. As the patient is active at 9 months of age, with no clinical signs of MDS, the results confirm that the absence of locus D17S34 does not lead to the phenotypic expression of MDS. Furthermore, this deletion should assist in defining the distal limits of this contiguous gene syndrome. 相似文献
4.
Synthetic soluble (—)-dopa melanin was prepared in deuteriated buffer, pH 8, by autooxidation of the precursor. At 6 mM of the precursor, the incorporation was over 90%. The changes in the line width measurements of N-CH3 protons of enantiomers of ephedrine in the soluble melanin were quantified by NMR spectroscopy. The dissociation constants of (—)-1R,2S-ephedrine, (+)-1S,2R-ephedrine, (—)-1R,2R-ψ-ephedrine, and (+)-1S,2S-ψ-ephedrine were 11.7, 4.20, 3.60, and 4.80 mM, respectively. Since the concentration of (—)-dopa was known and since the conversion of (—)-dopa to indole units of melanin was considered as 1:1, the stoichiometry of the interaction between the drug and the indole unit was calculated. Based on the dissociation constants of the enantiomers, it appears that up to four molecules of (—)-ephedrine can interact with one indole unit of the melanin, while such a ratio for other isomers appear to be 2:1. The preference by indole units of melanin is stereoselective. © 1992 Wiley-Liss, Inc. 相似文献
5.
Redox titrations of the iron-sulphur clusters in fumarate reductase purified from Escherichia coli, monitored by ESR spectroscopy, identified three redox events, similar to those observed in other fumarate reductases and succinate dehydrogenases: Centre 1, a [2Fe-2S] cluster, at g = 2.03, 1.93, appeared on reduction with Em = -20 mV. Centre 3, probably a [3Fe-xS] cluster, at g = 2.02 appeared in the oxidized state with Em = -70 mV. Centre 2 has been observed as an increase in the electron-spin relaxation of Centre 1. It titrates as an n = 1 species with Em = -320 mV, but in our hands did not appear to contribute significant intensity to the g = 2.03, 1.93 signal. It therefore appears to be an additional centre which undergoes spin-spin interaction with Centre 1. The reduction of Centre 2 coincided with the appearance of an extremely broad ESR spectrum, observed at temperatures below 20 K, with features at g = 2.17, 1.9, 1.68. The broad signal was observed in both soluble and membrane-bound preparations. Its midpoint potential was -320 mV. Its integrated intensity was approximately equal to that of Centre 1, if its broad outer wings were taken into account. Consideration of the ESR properties of this signal, together with the amino acid sequence of the frdB subunit of the enzyme, indicates that Centre 2 is a [4Fe-4S] cluster which, in its reduced state, enhances the spin relaxation of the [2Fe-2S] Centre 1. 相似文献
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Total sugars, reducing sugars, and phenols were estimated in internodes of tolerant and highly susceptible sovhum genotypes to charcoal, ln tolerant genotypes the sugar level was 2 to 3 times higher than in susceptible ones; phenol concentration also was higher in tolerant genotypes. In tolerant genotypes, sugar and phenol concentration was high in the lower most and in the upper most mternode. This may be used to identify sources of resistance. 相似文献
8.
A purification of ;malic' enzyme from potato is described. The purified enzyme is specific for NADP and requires a bivalent cation for activity. At pH values below 7 the plot of rate versus malate concentration approximates to normal Michaelis-Menten kinetics. At pH values above 7 the plot of rate versus malate concentration is sigmoid. A number of dicarboxylic acids activate the enzyme and remove the sigmoidicity. The enzyme is inhibited by phosphate, triose phosphates and AMP. In general, effectors of the oxidative decarboxylation of malate behave in the same manner in the reductive carboxylation of pyruvate. The response of the enzyme to energy charge is reported and the physiological significance of the response to metabolites is discussed in relation to the proposed role of the enzyme in the control of pH. 相似文献
9.
Amino acid sequence of the regulatory-site glyoxylate peptide of biodegradative threonine dehydratase of Escherichia coli.
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Incubation of purified Escherichia coli biodegradative threonine dehydratase with glyoxylate resulted in covalent binding of 1 mol of glyoxylate per mol of protein with concomitant loss of enzyme activity. The glyoxylate-binding site was identified as a heptapeptide representing amino acid residues Ser-33-Asn-Tyr-Phe-Ser-Glu-Arg-39 in the protein primary structure. Addition of glyoxylate to a culture of E. coli cells led to time-dependent enzyme inactivation. Immunoprecipitation with anti-dehydratase antibody of extract from [14C]glyoxylate-treated cells revealed labeled dehydratase polypeptide. These results are interpreted to mean that enzyme inactivation by glyoxylate in E. coli cells is associated with covalent protein modification. 相似文献
10.
V. S. Gupta M. S. Dhar B. G. Patil G. S. Narvekar S. R. Ra Wat P. K. Ranjekar 《Journal of biosciences》1990,15(4):261-269
Rice long repetitive DNA (9–20 kbp) reassociating at Cot 50 M.s was cloned in pBR325. Out of several recombinants (Camr Ampr Tets), only a few were selected randomly for further characterization. The insert size in all these clones was 3–4 kbp. Restriction
enzyme analysis showed the absence ofEcoRI andBclI sites, presence of a singlePstI andPvuII site and multiple sites forAluI in 3 clones namely pRLl, pRL7 and pRL10.
TheBamHI-PstI fragment of about 0.4 kbp in the pRL7 insert DNA (pRL7-0.4 kbp) was subcloned in M13mpl8 and partially sequenced using Sanger’s
dideoxynucleotide chain termination method. Dot matrix comparison of this sequence with rice rDNA sequences revealed low homology
with the 25 S rDNA sequence of rice, however, hybridisation did not indicate any homology. 相似文献