Pyridoxine requirements

Aspergillus sp. CH-Y-1043 was used as the prototrophic parental strain. The auxotrophic mutants A200 ade- (an adenine-requiring mutant) and A400 pyr (a pyridoxine requiring mutant) were isolated from the parental strain by treatment with N-methyl-N -nitro-nitrosoguanidina (NTG) as described previously (10). 

Pyridoxine has been used to counteract nausea during pregnancy. Mothers who use pyridoxine supplements give birth to babies with higher pyridoxine requirements. Pyridoxine dependency has been reported in some newborns with seizures and pyridoxine treatment reverses the seizure activity in these infants (Bernstein,... 

It was suggested that the tests may indicate pyridoxine requirement... 

The discrepancies between the amount of pyridoxine required to suppress abnormal xanthurenic acid excretion and to eliminate the convulsions in these infants suggests that an aberrant metabolism of trypto-... 

These studies indicate an intimate relation between the magnesium level of the diet and the pyridoxine requirement. It is suggested (A6) that, insofar as growth and urinary excretion of citrates, oxalates, and xanthurenic acid are concerned, high levels of magnesium appear to have a sparing effect on very low dietary levels of pyridoxine. 

With the exception of glycogen phosphorylase (Chapter 15), and kynureninase, all of the pyridoxine-requiring... 

Contraceptive steroids, especially estrogens, produce abnormalities in tryptophan metabolism in the great majority of women who use them. Evidence of absolute Bo deficiency is much less common, and the amount of pyridoxine required to correct urinary output of tryptophan metabolites is much higher than what is found in normal diets. The studies reviewed provide at least a partial understanding of the biochemical basis for these phenomena. 

Many mutant microorganisms are known to require, as a supplement to the medium in which they are grown, a substance that is synthesized by the corresponding wild-type organism (the normal strain). An example is the pyridoxine-requiring mutant of Neurospora sitophila reported by G. W. Beadle and E. L. Tatum in their first... 

The observed rate of growth of a pyridoxine-requiring Neurospora mutant (Beadle and Tatum, 1941), as function of the concentration of pyridoxine in the medium. 

Pappenheimer, Jr., and Hottle (277) observed another relation between pyridoxin requirements and cultural conditions with Streptococcus hemo-Note added in proof. 

Whether the CO was needed for purine synthesis or whether the purine played a part in producing CO, which was needed for growth, was not determined. With many bacteria, CO is essential at least for the initiation of growth (c/. 106). These observations should be compared with the relation between pyridoxin requirement and 0 tension observed by Boho-nos, Hutchings, and Peterson (15) (see Section IV, 3) and the uracil-0 effect found by Richardson with Staph, aureus (293). 

---