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31.
I A Bochkov M Kravi A I Tse?tlina A Kh Ka?tmazov M S Shevchuk G S Barsukova 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1991,(10):19-22
The formation of microflora on the laryngeal mucosa in newborn infants during the first 5 days of their life was studied in one of the maternity hospitals of Moscow. In this work modern methods of the isolation and identification of aerobic and anaerobic microorganisms were used, and the results thus obtained were computer-processed. In the maternity hospital of the "mother-child" type the microbial colonization of the laryngeal mucosa by normal and opportunistic microorganisms was noted in newborn infants. A wave-like course of the formation of laryngeal microflora, indicative of microbial succession occurring in the child, was revealed. The attempt to establish the cases of microbial interference between the species colonizing the laryngeal mucosa revealed that it was very rarely observed in 5-day-old newborns. This feature was seemingly the cause of low resistance of the larynx to colonization in newborn infants, which determined frequent colonization of their laryngeal mucosa with Staphylococcus aureus and Klebsiella. 相似文献
32.
Liquid extraction is one means of removing metabolic products continuously during a fermentation and so reducing product inhibition. It is known that microbial organisms are attracted to liquid-liquid interfaces, and it is important for the design of extraction systems to establish if this has a detrimental effect on the rate of extraction. The extraction of ethanol from aqueous suspensions of yeast (Saccharomyces cerevisiae) using n- decanol is described in this paper. It was found that the presence of the yeast cells severely reduced the rate of ethanol extraction. The overall mass transfer coefficient was reduced from 5.0 x 10(-6) to 0.7 x 10(-6) m/s. This reduced overall mass transfer coefficient was unaffected by yeast concentration in the range 0.1-20 kg/m(3). The results are consistent with the yeast cells adsorbing to the interface in closely packed layers and preventing mass transfer by simply reducing the available interfacial area. Optical microscope observations confirmed that a yeast layer several cell diameters thick rapidly built up at the interface when a small decanol droplet was added to a yeast suspension. 相似文献
33.
Addition of 2-(3-chloro-4-trifluoromethyl)anilino-3,5-dinitrothiophene (ANT2p) to detergent-solubilised Photosystem II (PS II) particles results in the photo-oxidation of carotenoid and inhibition of the steady-state oxygen-evolution rate. It has been proposed that ANT2p may modify the water-splitting reactions by mediating the transfer of reducing equivalents from endogenous electron donors, such as carotenoid, to the S2 and S3 oxidation states of PS II. In this paper we present evidence indicating that ANT2p can interact with PS II at two separate loci. The water-splitting complex is shown to be the primary site of attack by ANT2p, since artificial electron donors, such as 1,5-diphenylcarbazide (DPC), can restore PS II photochemical activity by feeding reducing equivalents directly to the reaction centre. The ANT2p interaction at this site is light-intensity dependent. A second inhibitory site close to the reaction centre P-680 chlorophyll is detected at slightly higher ANT2p concentrations. The inhibition at this site is unaffected either by changes in the actinic light intensity or by the addition of electron donors. The flash-induced oxidation of carotenoid has an ANT2p concentration dependence and an insensitivity to DPC which suggests that it results from the inhibition of the reaction centre and not with that of the water-splitting complex. 相似文献
34.
Nigel L. Brown Tapan K. Misra Joseph N. Winnie Annette Schmidt Michael Seiff Simon Silver 《Molecular & general genetics : MGG》1986,202(1):143-151
Summary The DNA sequences of the mercuric resistance determinants of plasmid R100 and transposon Tn501 distal to the gene (merA) coding for mercuric reductase have been determined. These 1.4 kilobase (kb) regions show 79% identity in their nucleotide sequence and in both sequences two common potential coding sequences have been identified. In R100, the end of the homologous sequence is disrupted by an 11.2 kb segment of DNA which encodes the sulfonamide and streptomycin resistance determinants of Tn21. This insert contains terminal inverted repeat sequences and is flanked by a 5 base pair (bp) direct repeat. The first of the common potential coding sequences is likely to be that of the merD gene. Induction experiments and mercury volatilization studies demonstrate an enhancing but non-essential role for these merA-distal coding sequences in mercury resistance and volatilization. The potential coding sequences have predicted codon usages similar to those found in other Tn501 and R100 mer genes. 相似文献
35.
Astrid G. Chapman Michael J. Halsey Geneen P. Hart Nigel P. Luff Brian S. Meldrum Bridget Wardley-Smith 《Journal of neurochemistry》1986,47(1):314-317
Regional amino acid concentrations were measured in rat brain fixed by microwave irradiation at three levels of elevated atmospheric pressure corresponding to different phases of the high-pressure neurological syndrome [20 atmospheres absolute (ATA), no clinical signs; 60 ATA, tremor; 85 ATA, severe tremor and myoclonic jerks]. No changes in amino acid content occurred at 20 or 60 ATA. At 85 ATA glutamine content increased in hippocampus, striatum, cerebellum, and substantia nigra, and gamma-aminobutyric acid content increased in hippocampus. It is suggested that enhanced glutamate release in various subcortical structures contributes to the myoclonic activity observed at 85 ATA. 相似文献
36.
The major sesquiterpenes in the foliage of Dacrydium cupressinum are α-longipinene, longifolene, longibornyl acetate, caryophyllene, caryophyllene oxide, humulene, α- and β-selinene, β- and δ-elemene, aromadendrene and the rare 9βH-caryophyllene. Sesquiterpene levels vary greatly from tree to tree. As this variation is largely independent of environmental factors, genetic control is proposed. Longifolene and α-longipinene levels are closely correlated, as are those of caryophyllene and humulene. The biosynthetic implications of these correlations are discussed. 相似文献
37.
The Thy-1 glycoprotein is a very abundant cell surface molecule of rat thymocytes and neuronal cells with the properties of a molecule that inserts into the lipid bilayer. The hydrophobicity is due to a glycophospholipid component covalently attached to the carboxy group of the C-terminal cysteine residue. The mature glycoprotein does not contain a stretch of hydrophobic amino acids that could traverse the membrane bilayer. These findings present a new mode of membrane attachment for a cell surface molecule that can mediate lymphokine release and cell division after cross-linking by antibodies. 相似文献
38.
Histochemical demonstration of calcium ions in the respiratory part of the rabbit lungs has revealed that the greatest amount of the reaction granules is localized in type II alveolocytes. "Calcium packs" have been discovered, on the basis of which osmiophilic laminar bodies are formed. Cooling of the body entails an increase in the number of osmiophilic laminar bodies with calcium oxalate granules in type II alveolocytes. 相似文献
39.
A method is described which allows a large number of bacterial strains to be rapidly and easily screened for the presence of site-specific endonucleases. The method involves selective permeabilization of the bacterial cell and analysis of the exuded material. Type II restriction endonucleases from cyanobacteria and Gram-negative eubacteria have been detected and new enzymes have been found. The method should be widely applicable and easy to modify for use in genera other than those tested. Three-site-specific endonuclease activities, detected by this method in Aphanothece halophytica PCC 7412, were purified and their recognition and cleavage specificities were determined AhaI and AhaII recognise and cleave the same DNA sequences as CauII and AcyI respectively; the specificity of AhaIII (TTTAAA) has been reported previously (Whitehead and Brown, 1982, FEBS Letters 143:296–300).Abbreviations Brij-58
20 cetyl ether
- Pu
purine nucleoside
- Py
pyrimidine nucleoside 相似文献
40.
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