AbstractsBiology & Animal Science

A biochemical study of aging was conducted on mitochondria from the embryo axes of germinating new and old soybean seeds. Differential phosphorylative efficiency, an average P/O ratio of 3.03 of the new material compared to 1.44 of the old, was obtained when all the co-factors and substrate were provided. No difference in oxygen consumption of both materials was observed. In an attempt to delineate some of the changes that took place in the mitochondria of naturally aged soybean seed, the effects of serum albumin, naF, and 2, 4-dinitrophenol as well as the permeability of mitochondria membranes under different sucrose osmotic concentrations were examined. The highest P/O ratios of mitochondria from new and old materials were obtained in the presence of serum albumin. The effect of albumin was mainly in increasing phosphorylation with no change in oxygen uptake. The addition of 0.013M NaF per flask produced no change in oxygen consumption and phosphorylation on cashed mitochondria of both materials. However, the same concentration of NaF did improve the PIO ratio in the unwashed mitochondria in a preliminary experiment of the embryo axes of the new material. 2, 4-dinitrophenol used at the concentration of 0.001M per flask reduced slightly the oxygen uptake of the old but had no effect on that of the new material. The PIO ratios of both materials were reduced practically to the same level; namely, to 1.09 and 0.95 in the new and old, respectively. The conductivity of the leachate from the old material, based on any known quantity of mitochondria, was always higher than that of the new in 0.25M, 0.50M and 0.75M sucrose concentrations. Maximum difference in conductivity measured in μ mhos between the new and old was obtained in the 0.5M osmotic concentration. The experimental results indicate that mitochondrial phosphorylative efficiency of old but germinative soybeans are reduced to 48 percent of the new. This reduction is not because of higher content of adenosine triphosphatase in old material, but because of degradation in the integrity of mitochondrial membrane. This kind of degradation might result in uncoupling of electron transporting and phosphorylative systems.