Effect of dietary restriction and aging on polyploidy in rat liver.

Liver polyploidy levels were compared as a function of age and diet in male Fischer 344 rats between 1 and 24 months of age. Dietary restriction was imposed on one group by reducing their food intake to 60% of ad libitum food intake. Histological sections of the livers of animals at each age and diet were examined.

The effects of UV radiation and antioxidants on life span and lipid peroxidation in the rotifer Asplanchna brightwelli.

Lipid peroxidation (LP) rates and life span were determined in control and in ulraviolet (UV) irradiated rotifers of the species Asplanchna brightwelli. UV irradiation administered at 6 h of life significantly increased the rate of LP as the rotifers aged; it also produced a significant shortening of rotifer life span. Pretreatment with 20 microg/ml of vitamin E blocked the increase in LP and the decrease in life span induced by UV radiation.

Spontaneous activity level and life span in rotifers: lack of support for the rate of living theory.

Spontaneous activity level was measured in rotifers of the species Asplanchna brightwelli on each day of their 5-day life span. No correlation was seen in group data between activity level and life span. However, data from individuals showed a positive correlation between life span and activity level in the latter half of the life span on 3 days out of 5.

Cortisone extends life span in the rotifer Asplanchna brightwelli.

Cortisone at 100 and 200 microM concentrations produced a significant increase in both life span and reproduction in the rotifer Asplanchna brightwelli. Two possible mechanisms are discussed to explain these results: (1) cortisone stabilization of lysosomal membranes, or (2) recognition of cortisone as a hormone capable of altering resource allocation by the rotifers.

The relationship between lifespan and reproduction in the rotifer Asplanchna brightwelli.

Lifespan is strongly correlated (0.7009) with the length of the reproductive period in the rotifer Asplanchna brightwelli. Lifespan is correlated to a lesser degree with the number of offspring produced (0.