[Delay and cessation of aging processes by manipulation of reproduction, food intake and development in insects]. / Verzögerung und Stillstand von Alterungsprozessen durch Manipulation von Fortpflanzung, Nahrungsaufnahme und Entwicklungsvorgängen bei Insekten.

Insects can serve as excellent models to show that the genetically determined life span of organisms as well as that of other traits is characterized by high phenotypic plasticity. Depending on different environmental conditions the life cycle strategy can therefore be highly variable. Thus developmental and aging processes are subjected to delaying or accelerating influences or can even be interrupted. Availability of protein to fulfill reproductive requirements, intermittent starvation, and the photoperiodic induction of reproductive diapause were taken as examples for the study of selected abiotic factors which influence the life history of the blowfly Phormia terraenovae and the beetle Gastroidea viridula.

Fifteen years of Phormia - on the value of an insect for the study of aging.

The blowfly Phormia is currently used for studying various aspects of aging. In the context of comparative life history studies this fly can be characterized as an example of an 'r' selected type with a short life span and explosive reproduction. This is in contrast to the mecopteran fly Panorpa which shows senescence even under free living conditions and represents the 'K' selected type. A sudden drop of flight performance, low levels of enzyme activities at the end of life and specific kinetic adaptations of single enzymes are part of the 'aging syndrome' of Phormia. In the context of general aging investigations Phormia proved to be a suitable model system. This is shown in several examples covering the age variation of oscillating glycolysis, the influence of the cell redox state on purified enzymes, and treatment with geriatrics.

[Insects as models in aging research?]. / Insekten als Modelle der Alternsforschung?

The multiplicity of different life forms in the world of organisms contrast strikingly with the uniformity of aging mechanisms. For this reason, even insects may be employed as model organisms for aging processes. Ultrastructural changes in aging mitochondria, for example, are also known in insect physiology. Further examples are changes in biochemical rhythms in old age and in the redox state of tissue; the latter may be of importance for an analysis of the efficacy of exogenous antioxidants.

Effects of age and physical performance capacity on distribution and composition of high-density lipoprotein subfractions in men.

The influences of age and maximal aerobic capacity (VO2max) on serum lipoproteins with special regard to the concentration, composition and distribution of high density lipoprotein (HDL) subfractions were investigated in 51 healthy males of different characteristics: younger than 35 years, untrained (n = 14, mean age 28.2 years, SD 6.0; VO2max, 47.9 ml.kg-1.min-1, SD 5.8) and trained (n = 11, mean age 27.9 years, SD 4.3; VO2max, 61.1 ml.kg-1.min-1, SD 5.1), older than 50 years untrained (n = 14, mean age 58.9 years, SD 5.9, VO2max, 29.3 ml.kg-1.min-1, SD 5.3) and trained (n = 12, mean age 59.3 years, SD 7.2, VO2max, 45.7 ml.kg-1.min-1, SD 7.7). The fasting-state serum concentrations of total cholesterol, tri-acylglycerol and lipoprotein-cholesterol were measured. The HDL-subfractions were separated by density (rho) gradient ultracentrifugation. Concentrations of cholesterol, cholesterylester, tri-acylglycerol, phospholipids, apolipoprotein (apo) A-I and A-II were measured in the subfractions HDL2b: rho = 1.063-1.100 g.ml-1; HDL2al: rho = 1.00-1.110 g.ml-1; HDL2a2: rho = 1.110-1.150 g.ml-1; HDL3: rho = 1.150-1.210 g.ml-1. Elderly untrained subjects showed increased serum concentrations of total-, very low- and low density lipoprotein-cholesterol and elevated tri-acylglycerol levels. The HDL-cholesterol concentration was decreased, due to reduced concentrations of HDL2-subfractions. Significant changes in the composition of HDL2-subfractions were found in elderly untrained subjects. The HDL2-subfractions had more protein, a decreased apoA-I:A-II ratio and less phospholipids in comparison to HDL2-subfractions from younger untrained and trained, and elderly trained subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Age dependent changes of a biochemical rhythm--the glycolytic oscillator of the blowfly Phormia terraenovae.

1. By monitoring changes of fluorescence of NADH the frequencies, amplitudes and maximum slopes of the glycolytic oscillator of Phormia were analyzed in 5, 9, 15 and 21-day-old male flies. 2. In order to evaluate the possible existence of circadian rhythms within the oscillatory system, all determinations were repeated eight times/day. 3. In addition, the activities of three key enzymes of glycolysis, PFK, GAPDH and PK, which are central to the glycolytic oscillator were measured with respect to age and day time. 4. With increasing age the amplitudes of oscillations increased together with the maximum slopes of the oscillatory waves. The frequency appeared to be independent of age. 5. Variations of enzyme activities over the day indicated an age dependent circadian rhythm which, due to the simultaneous activity changes of the three measured enzymes, was not reflected in the whole oscillatory system. 6. The results suggest that modifications in the allosteric regulation of enzymes are responsible for the age dependent changes of the glycolytic oscillator.

The quantitative relationship between life span, food ingestion, egg production, mating, and flight-activity of protein-fed blowfly Phormia terrae novae females.

The age-dependent variations in the amount of food ingestion, egg production, and flight activity of protein-fed female Phormia terrae novae were analyzed. Also the influence of mating and forced physical performance on the time course of these parameters and on life span were tested. In virgin females, the life span with the investigated factors is generally delayed, together with mean and maximum life span. In comparison to mated females virgin females exhibit a 40% prolongation of mean life span and ingest more sugar with a later intake maximum. Their egg production starts 5 days later (Day 10) but reaches only half the amount occurring in mated females. Flight performance is generally higher in virgin females, reaching its maximum 2 days later (Day 14), with a more gradual decline instead of the sudden drop in flight performance seen in mated flies. Females receiving their food by flight only ("forced fliers") show a shorter mean life span (which is more pronounced in virgin flies). The maximum of sugar intake shifts forward to an earlier point after eclosion, and the amount is reduced by about 30% over the entire life span. Similarly, the egg production rate reaches lower values and tends to have an earlier maximum in comparison to corresponding groups that had access to sugar on the cage floor. The results further support the hypothesis that Phormia exhibits a strictly programmed aging pattern. Its time course depends on reproduction sufficiency and physical performance. Both factors act to shorten life expectation.