Amino acid requirements for growth of two isolates of Chlamydia pneumoniae were studied and compared with those for one strain of Chlamydia trachomatis in a HeLa 229 cell culture. It was shown that among 13 amino acids in Eagle minimum essential medium, C. pneumoniae required all amino acids except lysine. A true requirement for arginine, isoleucine, leucine, threonine, and valine could not be ...

Previous work with growing swine indicated that the lysine requirement, expressed as a percentage of the diet, decreased by .02 percentage units with each 1% reduction in dietary protein level. Thus, the dietary lysine needed for optimal performance may be less than the reported requirement when a portion of the soybean meal in a corn-soybean meal diet is replaced with crystalline lysine. An ex...

A mutant of Esckch ia coZi waa isolated which showed a requirement for methionine + lysine when a fairly large inoculum of washed organisms was used. Cystathionine or homocysteine replaced methionine, and diaminopimelic acid replaced lysine; no other amino acid or growth factor was active. The amounts of the amino acids required to promote growth were only about one-tenth of the quantity of met...

Experiments (Exp.) were conducted with Cornish Rock males (4 to 14 or 15 d of age) to determine the Lys requirement (Exp. 1) and the optimum ratio of TSAA:Lys for chicks fed adequate or inadequate Lys (Exp. 2). In Exp. 1, 180 chicks were allotted on the basis of BW to six treatments with six replications of five chicks each in a completely randomized design (CRD). Average initial and final BW w...

Accumulation of tricarboxylic acids related to lysine biosynthesis has been demonstrated in a yeast mutant, Ly,,, which requires lysine as a growth factor in synthetic medium but can substitute a-aminoadipic acid for the nutritional requirement of lysine. Both radioactive and nonradioactive intermediates have been isolated from the growth medium under appropriate conditions and have been identi...

The processes of natural selection shape the efficiency of nutrient use by animals, with some being especially thrifty while others are wasteful. An examination of the widely divergent amino acid economies of different species vividly illustrates this basic nutritional principle. The domestic cat evolved as a carnivore and has a very high maintenance requirement for dietary amino acids. The cat...