Hymenolepis diminuta: The Microbial Fauna, Nutritional Gradients, and Physicochemical Characteristics of the Small Intestine of Uninfected and Parasitized Rats

1971 ◽  
Vol 49 (11) ◽  
pp. 972-984 ◽  
Author(s):  
D. F. Mettrick
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Small Intestine ◽  
Trichloroacetic Acid ◽  
Inverse Correlation ◽  
Physicochemical Characteristics ◽  
Hymenolepis Diminuta ◽  
Soluble Carbohydrate ◽  
Molar Ratios ◽  
Number Of Microorganisms

In uninfected rats the amount of trichloroacetic acid (TCA) soluble and insoluble carbohydrate in the small intestine declined steadily from duodenum to ileum. In rats infected with 10 16-day-old Hymenolepis diminuta these gradients were reversed and there was a 54% increase in the amount of TCA-soluble carbohydrate, and a 110% increase in the amount of glucose present in the luminal contents.In uninfected rats the amounts of TCA-soluble and -insoluble nitrogen and of total lipid in the small intestine were considerably more than in the intestine of infected rats. The differences may represent utilization by the worms of these nutrients.In parasitized rats the concentrations and molar ratios of the amino acids of the intestinal amino acid pool were significantly different (P < 0.001) in every region of the gut from those in uninfected animals.The intestinal pH of parasitized rats was lower than that in uninfected rats, and the pH gradient showed an inverse correlation with worm biomass and lactic acid distribution.The number of microorganisms present in the small intestine and colon of parasitized rats was less than half that in uninfected animals. Escherichia coli and the coliforms showed the greatest decrease in numbers. Other common aerobes were also markedly reduced in number. Anaerobic enterococci and yeasts were absent in the parasitized animals; anaerobic streptococci and micrococci were restricted to the ileum.

scholarly journals Association of nascent polypeptide with 30S ribosomal subunits

1973 ◽  
Vol 136 (4) ◽  
pp. 859-863 ◽  
Author(s):  
Michael Cannon ◽  
M. Amin A. Mirza ◽  
Margaret L. M. Anderson
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Trichloroacetic Acid ◽  
Sucrose Gradient ◽  
Gradient Centrifugation ◽  
Ribosomal Subunits ◽  
Nascent Polypeptide ◽  
Sucrose Gradient Centrifugation ◽  
Crude Extracts

1. Crude extracts of Escherichia coli were used to synthesize nascent peptides under the direction of endogenous mRNA and in the presence of radioactive amino acids. Analysis of such extracts by sucrose-gradient centrifugation in low Mg2+concentration has shown that after 2min of incubation approximately 14% of the total labelled protein recovered on the gradient, in association with whole ribosomes, sediments with 30S ribosomal subunits; this value rises to approximately 24% after 30min of incubation. The labelled protein associated with 30S ribosomal subunits is insoluble in hot trichloroacetic acid. 2. Similar results were also obtained in extracts that synthesized polypeptides under the direction of either of the synthetic polyribonucleotides poly(A) or poly(A,G,C,U). In contrast, however, analysis of crude extracts programmed in protein synthesis by poly(U) has indicated that under these conditions 30S ribosomal subunits have no associated polyphenylalanine; similarly there is little associated peptide after programming of extracts by poly(U,C).

Chemotaxis and methionine metabolism in Escherichia coli

1972 ◽  
Vol 18 (5) ◽  
pp. 591-596 ◽  
Author(s):  
John B. Armstrong
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Trichloroacetic Acid ◽  
Methionine Metabolism ◽  
Methionine Biosynthesis ◽  
Normal Cells ◽  
Active Product ◽  
The Third ◽  
Soluble Compound ◽  
Low Levels

Auxotrophic strains of Escherichia coli generally are motile and chemotactic in the absence of those amino acids needed for growth. Methionine auxotrophs, however, require low levels of methionine for chemotaxis. A prototroph, grown in the presence of methionine so as to repress methionine biosynthesis, also requires methionine for chemotaxis. In the absence of methionine the bacteria are still actively motile, and thus phenotypically resemble nonchemotactic mutants.A continuous supply of methionine is necessary for a normal chemotactic response, indicating the active product is labile. Under the conditions used to demonstrate chemotaxis, the major trichloroacetic acid (TCA) soluble metabolites of methionine are spermidine, S-adenosylmethionine (SAM), and a third, as yet unidentified, compound. Spermidine is readily taken up by the bacteria, but does not replace methionine for chemotaxis. S-adenosylmethionine cannot be tested directly, as it is not taken up by normal cells. However, it is rapidly turned over and thus meets the requirement for lability. The third acid-soluble compound appears to be relatively stable metabolically.

Inhibition of the induced synthesis of protocatechuate oxygenase by o-nitrobenzoic acid

1970 ◽  
Vol 16 (7) ◽  
pp. 609-614
Author(s):  
Karen F. Montgomery ◽  
Norman N. Durham
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Trichloroacetic Acid ◽  
Protocatechuic Acid ◽  
Viable Cell ◽  
Insoluble Fraction ◽  
Nitrobenzoic Acid ◽  
Cell Counts ◽  
Oxygenase Activity

The synthesis of protocatechuate oxygenase (EC. 1.13.1.3), an inducible enzyme, by Pseudomonas fluorescens was inhibited by o-nitrobenzoic acid. The inhibitor did not alter the oxygenase activity of induced cells. Viable cell counts indicated that o-nitrobenzoic acid, in the concentrations used in these experiments, did not kill the cells. The inhibitor decreased the incorporation of L-tryptophan-14C and DL-glutamic-14C acid into the hot trichloroacetic acid insoluble fraction of the cell, but had no effect on the uptake of either radioactive amino acids or the inducer, protocatechuic acid. The synthesis of β-galactosidase by Escherichia coli was also inhibited by o-nitrobenzoic acid. The results establish that one site of o-nitrobenzoic acid inhibition is associated with protein synthesis in the cell.

Common modifications of selenocysteine in selenoproteins

2019 ◽  
Vol 64 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Elias S.J. Arnér
Keyword(s):  
Amino Acids ◽  
Covalent Binding ◽  
Physicochemical Characteristics ◽  
Redox Active

Abstract Selenocysteine (Sec), the sulfur-to-selenium substituted variant of cysteine (Cys), is the defining entity of selenoproteins. These are naturally expressed in many diverse organisms and constitute a unique class of proteins. As a result of the physicochemical characteristics of selenium when compared with sulfur, Sec is typically more reactive than Cys while participating in similar reactions, and there are also some qualitative differences in the reactivities between the two amino acids. This minireview discusses the types of modifications of Sec in selenoproteins that have thus far been experimentally validated. These modifications include direct covalent binding through the Se atom of Sec to other chalcogen atoms (S, O and Se) as present in redox active molecular motifs, derivatization of Sec via the direct covalent binding to non-chalcogen elements (Ni, Mb, N, Au and C), and the loss of Se from Sec resulting in formation of dehydroalanine. To understand the nature of these Sec modifications is crucial for an understanding of selenoprotein reactivities in biological, physiological and pathophysiological contexts.

scholarly journals ANTIPODAL SPECIFICITY IN THE INHIBITION OF GROWTH OF ESCHERICHIA COLI BY AMINO ACIDS

1948 ◽  
Vol 174 (2) ◽  
pp. 391-398
Author(s):  
Yutaka. Kobayashi ◽  
Marguerite. Fling ◽  
Sidney W. Fox
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Inhibition Of Growth

scholarly journals Fimbriae in Escherichia Coli Isolated from the Small Intestine of Piglets

1986 ◽  
Vol 27 (2) ◽  
pp. 235-242
Author(s):  
Berit Κ. Djønne ◽  
Eivind Liven
Keyword(s):  
Escherichia Coli ◽  
Small Intestine
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