Hildegard E. Enesco

α-Tocopherol increases lifespan in the rotifer Philodina

Abstract The addition of α-tocopherol (vitamin E) to the culture medium at a concentration of 10 −4 was found to significantly extend the average lifespan of the rotifer Philodina . The oily α-tocopherol was solubilized in Tween-80 so that it would dissolve in the aqueous culture medium. Tween-80 alone had no effect on the lifespan or fecundity of the rotifers. Addition of α-tocopherol also caused a significant increase in the number of offspring per rotifer.

Influence of low tryptophan diet on survival and organ growth in mice.

Greater survival and reduced growth were found to characterize mice on a tryptophan deficient diet as compared to fully fed control mice. The 50% survival point was reached by the tryptophan restricted group at 683 days, and by the control group at 616 days. Measurements of body weight, organ weight, and DNA level were made at 8, 12, 24, 36, 52 and 78 weeks of age. Both whole body weight and organ weight of liver, kidney, heart and spleen were about 30% lower in the tryptophan restricted group as compared to the controls, so that the ratio of organ weight to body weight remained at a constant value for both groups. There was no significant change in cell number as determined by DNA measurements, as a result of the tryptophan restriction.

Dietary restriction reduces fluorescent age pigment accumulation in mice

Abstract The influence of dietary restriction of lipid peroxidation fluorescent products, or lipofuscin, was examined in brain and heart in male Swiss albino mice at 3, 5, 7 and 12 months of age. The level of fluorescent products was significantly lower in the brain of mice on the restricted diet as compared to control mice in all age groups. By 12 months of age, the level of lipid peroxidation fluorescent products was significantly lower in the heart tissue of mice on the restricted diet as compared to control mice. Dietary restriction may retard lipofuscin accumulation by reducing the level of free radical-reactions.

The effect of temperature and of dietary restriction on lifespan and reproduction in the rotifer Asplanchna brightwelli

In this study, the effects of different environmental temperatures and of dietary restriction on the lifespan, reproductive cycle, and fecundity of the rotifer Asplanchna brightwelli were examined. When temperature effects were analyzed, it was observed that the mean lifespan and the times at which the reproductive cycle started and ended all increased as environmental temperatures decreased. When dietary restriction was imposed by increasing the interval between feeding times from 12 to 36 hours, there was an increase both in the mean lifespan and in the length of the reproductive period in this rotifer.

Liver polyploidy: Influence of age and dietary restriction

Polyploidy increases with age in mammalian liver. Since dietary restriction increases lifespan, the question posed in this study was whether liver polyploidy would be influenced by dietary protein restriction. Restricted mice were fed a 4% protein diet, while control mice received a 26% protein diet. Polyploidy was determined from measurements of nuclear diameter on liver of 3 week, 1 1/2, 3, 10, 20 and 24-1/2 month old Swiss albino mice. The percentage of polyploid cells increased steadily with age. The rate of increase, expressed as the polyploidization index, was greater in the fully fed control animals as compared to the animals on protein restriction. Protein restriction thus retards the age associated process of polyploidization of liver nuclei. Nuclear diameter increased slightly with age, but was not influenced by protein restriction.

Rotifers in aging research: use of rotifers to test various theories of aging

Four theories of aging are discussed to examine how effectively they might explain the aging process in rotifers. One of the early theories, the rate of living theory of aging can perhaps be discounted. Although the theory predicts that increased biological energy expenditure, in the form of increased activity or reproduction, would lead to a shorter lifespan, these predictions are not born out by experimental evidence. At the whole animal level, a case can be made for a theory of programmed aging, where the end of reproduction signals the end of the lifespan. Support for this view comes from the observation that lifespan is positively correlated with reproductive parameters, that treatments that extend lifespan usually act to extend the reproductive period, and that the end of reproduction is associated with high mortality and senescent biochemical changes. Two molecular theories of aging are also discussed; the free radical theory of aging and the calcium theory of aging. These theories point to the fact that molecular damage accumulates and that calcium influx increases in the course of aging. When free radical buildup or calcium homeostasis is reduced, lifespan is extended. A molecular explanation of aging does not necessarily exclude the idea of programmed aging. It is probable that an eventual understanding of the aging process will rest on both a physiological and molecular basis.

Effect of antioxidants on rotifer lifespan and activity

The antioxidant thiazolidine-4-carboxylic acid (TCA) is a sulfhydryl radical scavenger. At concentrations of 400 or 800 uM it was found to significantly extend the mean lifespan of the rotifer Asplanchna brighwelli by 7.8%. Maximum lifespan of A. brighwelli was not influenced by this drug. Butylated hydroxytoluene (BHT), a true chain-breaking antioxidant, was toxic to the rotifers. Vitamin C, an antioxidant of the reducing agent category, had no effect on rotifer lifespan. Although TCA brought about a significant increase in mean rotifer lifespan, it did not significantly affect the activity level of the rotifers. The results presented here are consistent with the free radical theory of aging.

Life span and age-related changes in activity level of the rotifer Asplanchna brightwelli: Influence of curare

The rotifer Asplanchna brightwelli shows a continuous decline in swimming activity through the course of its 5-day life span. This activity loss occurs at a slower rate when rotifers are treated with very low dosages (0.00025% to 0.0005%) curare. Rotifers treated with these low dosages of curare have a significantly longer life span than that of untreated control rotifers.

A study of dietary restriction and lifespan in the rotifer Asplanchna brightwelli monitored by chronic neutral red exposure

The rotifer Asplanchna brightwelli could be exposed to concentrations of neutral red at 0.1 to 0.75 microgram/ml for two consecutive generations with no adverse effect on the lifespan or fecundity of either generation. Chronic exposure to higher concentrations of neutral red caused reductions in both lifespan and fecundity of the rotifers. Because neutral red stains the Paramecium which serve as a food source for the rotifers, the extent of red coloration in each rotifers gut gave an approximation of how much food that rotifer had consumed. The Paramecium concentration had to be reduced to 100 per ml before pale gut coloration provided clear evidence of reduced food intake or dietary restriction. The group of rotifers with reduced food intake had a significantly longer lifespan than any other group. Their lifespan was 14.2% longer than that of control rotifers.

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. This tendency toward greater activity in the longer-lived rotifers is not consistent with the rate of living theory of aging.