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SummaryA study in young rats (weanling to 7 weeks of age) has shown that: (1) Liver mitochondria from rats with induced hyperthyroidism were less efficient as energy transducers than controls, as judged by lower P/O ratios. (2) Liver mitochondria from hyperthyroid rats contained more coenzyme Q than did controls. (3) Accordingly, coenzyme Q probably is not involved as an intermediate for phosphorylation; but rather, in the hyperthyroid state is in an alternate pathway of electron transport by-passing phosphorylation. (4) Methionine, under the conditions of the study, exerted no antithyrotoxic effect in terms of coenzyme Q content or P/O ratios of liver mitochondria.

SummaryFeeding cockerels depleted of Vit. B12 from the second to fourth weeks of age on a 70% sesame meal diet deficient in Vit. B12 and lysine resulted in a failure of morphological differentiation of testicular tissue accompanied by a decrease in comb growth. Supplementation with Vit. B12 and lysine produced markedly greater testicular growth and differentiation over that in the normal controls.

INTRODUCTION IN EARLIER work it was observed that vitamin B12 supplementation of deficient basal diets led to reduced blood levels of certain free amino acids. The chicks given vitamin B12, with lower blood levels of these amino acids grew faster, and made more efficient utilization of their feed than did the controls. This finding led to the provisional hypothesis that vitamin B12 enhances anabolic utilization of amino acids in the chick (Charkey et al., 1950); confirmed by Menge and Combs (1950). The present paper reports a further study in which that hypothesis has been put to more comprehensive test. EXPERIMENTAL Plan of Experiment. It was desired first of all to repeat, in essence, the earlier work in which effects had been observed on an ad libitum feeding basis. These effects had not been large, however, and it was thought that they might be increased by resampling all treatments after putting …

SummaryDietary iodinated casein led in chicks given dietary vit. B12 to higher cecal contents of vit. B12 and in chicks not given dietary vit. B12 to lower liver contents of vit. B12 than those found in respective controls. It is suggested that the ability of iodinated casein to increase the sensitivity of chicks to dietary vit. B12 is due in part to an interference with intestinal absorption of the vitamin.

GLUTATHIONE (GSH) is widely distributed in living tissue and is maintained therein in relatively large amounts, as compared to most other soluble low molecular weight components of tissues. It appears to be primarily an intracellular substance, being present, if at all, in undetectable amounts in extracelllular fluids (Jocelyn, 1959; Long, 1961). Erythrocytes on the other hand contain, in common with cells in general, considerable amounts (Long, 1961). Owing to its thiol group GSH functions in oxidation-reduction reactions in tissues (Jocelyn, 1959; Mapson, 1959). It is capable of interaction in various ways with disulfide bridges of proteins (Jensen, 1959; Boyer et al., 1959); a function which is potentially of the utmost importance, as in mitosis (Rapkine, 1931; Mazia, 1954), and in the functioning of hormones (Ressler, 1958; Lazarow, 1954) and of thiol-dependent enyzmes (Vollmer, 1954; Boyer et al., 1959; Mapson, 1959), for instance. Ever since its isolation from yeast by Sir…