Response of the canine duodenum to intraluminal challenge with cholera exotoxin

In response to intraluminal challenge with crude cholera exotoxin, canine Thiry-Vella duodenal loops consistently produced isotonic fluid for a 24-36 hr period. Isotonic fluid production generally began within 15 min after challenge. Mean bicarbonate concentration of fluid produced by duodenal loops was 24+/-6 (SD) mEq/liter. Perfusion of exotoxin-treated duodenal loops with an isotonic electrolyte solution containing glucose 60 mOsm/liter caused a significant decrease in exotoxin-induced isotonic fluid output. The net effects of glucose on isotonic fluid absorption by perfused duodenal loops were not significantly different before and after administration of crude cholera exotoxin. The response of canine duodenal loops to challenge by cholera exotoxin differs from responses of jejunal and ileal loops in a) absence of a detectable "lag period" between administration of exotoxin and initiation of net fluid output; b) a longer period of fluid production following exotoxin administration; and c) a significantly greater net fluid output per unit length of gut. The mean bicarbonate concentration of the fluid produced by duodenum is less than that produced by ileum, but is not significantly different from that produced by jejunum. The duodenal response is similar to that of the more distal small bowel segments in that an effect on isotonic fluid movement is observed shortly after exotoxin administration and the maximum rate of exotoxin-induced isotonic fluid production is not reached until 4-5 hr after exotoxin administration. The basis for the consistent delay of 4-5 hr between intraluminal exotoxin administration and maximum gut fluid production has not yet been determined. Current data are consistent with the hypothesis that the rate of secretion of isotonic fluid induced by cholera exotoxin is not significantly different per unit length, in duodenum and ileum and that the lesser net fluid output in the ileum is due to the greater capacity for isotonic fluid absorption by the more distal small bowel segment.

Effects of penicillin and glycine on cell wall glycopeptides of the two varieties of Vibrio fetus

Actively growing strains of Vibrio fetus venerealis and V. fetus intestinalis, none of which produced penicillinase, were treated with inhibitory levels of penicillin or glycine, primarily to gain insight into the differential sensitivities of the two varieties to both of these compounds. Treatments induced the accumulation of uridine nucleotide glycopeptide precursors which contained amino sugars and amino acids in various molar ratios. Penicillin-induced nucleotides all contained muramic acid and sometimes glucosamine; they generally contained alanine, glutamic acid, diaminopimelic acid, and glycine. Approximately equimolar ratios of these components were observed in some compounds, but ratios varied considerably in others. Glycine-induced nucleotides contained muramic acid and, in some instances, glucosamine. Amino acids were detected only infrequently and usually in low molar ratios. The data suggest that penicillinase production, differences in the chemical composition of glycopeptide, and variations in modes of action of penicillin and glycine cannot individually account for the differential sensitivities of venereal and intestinal strains of V. fetus to these substances.

Intramolecular heterogeneity of the deoxyribonucleic acid of temperate bacteriophages

Spectral changes accompanying the thermal denaturation of phage deoxyribonucleic acid suggested that lambda is not unique in possessing large-scale intramolecular heterogeneity and nucleotide clustering; instead, lambda seems to share this property with other enteric phages.

A simple procedure for detecting the presence of cyclopropane fatty acids in bacterial lipids

Four gram-negative bacterial species, including Escherichia coli strain B, Serratia marcescens, Pseudomonas fluorescens, and Vibrio cholerae (comma) strain NIH 41, were investigated for fatty acid content by gas-liquid chromatography involving a preparatory technique which facilitated detection of cyclopropane fatty acids. Methyl esters of fatty acids were subjected to mild catalytic hydrogenation to eliminate unsaturates. Hydrogenation was followed by bromination which removed cyclopropane acids from chromatographic profile patterns. Lactobacillic acid (cis-11,12-methyleneoctanoate) and cis-9,10-methylenehexadecanoate, previously reported in lipids of E. coli and S. marcescens, were found in small amounts in P. fluorescens but were not detected in V. cholerae.

Aliphatic hydrocarbons and fatty acids of some marine and freshwater microorganisms

Gas chromatography and combined gas chromatography-mass spectrometry have been used to study the fatty acids and hydrocarbons of a bacterium from the Pacific Ocean, Vibrio marinus, a freshwater blue-green alga, Anacystis nidulans, and algal mat communities from the Gulf of Mexico. Both types of microorganisms (bacteria and algae) showed relatively simple hydrocarbon and fatty acid patterns, the hydrocarbons predominating in the region of C-17 and the fatty acids in the range of C-14 to C-18. The patterns of V. marinus were more comparable to those of the algal populations than to patterns reported for other bacteria. An incomplete correlation between fatty acids and hydrocarbons in both types of organisms was observed, making it difficult to accept the concept that the biosynthesis of hydrocarbons follows a simple fatty acid decarboxylation process.