E. D. Goldsmith

Aminopterin and Response of Frog Oviducts to Estradiol. II. Histological Studies and Mitotic Counts.

Summary Maeroscopically and microscopically, oviducts of frogs receiving aminopterin (4-amino pteroylglutamic acid) failed to respond to the growth stimulating action of estradiol. However, a significantly greater number of mitotic figures were visible in these oviducts, Evidence is presented to suggest that the folic acid antagonists may exert their growth inhibitory action by interfering with folic acid utilization in the organism, with a consequent reduction in nucleic acid synthesis, and a retardation of the rate of cell division.

Growth responses in Allium Cepa. Studies with 4-aminopteroylglutamic acid.

SUMMARYAminopterin, 4-amino-pteroylglutamic acid, was tested on root tips, root primordia and the seedlings of the onion, Allium Cepa, in concentrations varying from 4–5 × 10−4M to 2.3×10−8M (20 mgm to 0.001 mgm per 100 cc). The effects produced were not specific and may be listed as cytological, morphogenetic, necrotic and probably physiological.Aminopterin in varying concentrations apparently did not interfere with differentiation of tissues but affected mitosis by suppressing or slowing down the process of cell division. There was no indication that these effects were related to a change in nucleic acid content in cells of treated plants.It seemed that the stimulatory action of Aminopterin was mainly related to the phase of growth concerned with cell elongation, since linear growth equaling that of the controls was achieved by treated seedlings in which mitosis was completely or partly suppressed. These mitosis-inhibiting effects disappeared, however, upon prolonged treatment.The stunting effect of 0.0...

Effects of Thiouracil and Sodium 5, 5-Diphenyl Hydantoinate (Dilantin Sodium) on Resistance to Lowered Barometric Pressures.∗

Summary 1. Both dilantin and thiouracil prolong the survival time of rats subjected to reduced barometric pressures (148 mm Hg). 2. The combination is considerably more effective than either one acting alone. 3. The combination tends to reduce the extent of lung hemorrhage in rats subjected to decompression but has no effect on the development of lens cataract.

Effect of water-miscible preparation of vitamin D2 on metamorphosis of thiourea and citrate treated Rana pipiens larvae.

Summary An immersion experiment using hind-limb length increase of R. pipiens tadpoles has shown that although Vit. D2 enhances metamorphosis it does not counteract the effect of thiourea. Addition of citrate reduces the Vit. D2 effect.