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J Miquel

Publications and source records attributed to J Miquel.

At least 91 records · Page 5Linked to original sources
PubMed1981

Age-related activity changes in actomyosin ATPase and arginine phosphokinase in male Drosophila melanogaster Meig.

The specific activity of each of the two enzymes primarily concerned with the energy metabolism of flight muscle contraction was determined in male Drosophila melanogaster, from emergence through 5 weeks postemergence. Ca++-activated actomyosin ATPase activity rose rapidly from a minimum at emergence to a peak level at 4-5 days, falling gradually thereafter to a minimum level at 10-11 days postemergence, with no change thereafter. Arginine phosphokinase activity rose more gradually to a maximum at 11-12 days postemergence and then fell slowly to a minimum at 18-19 days. These data represent a sequential pattern of biochemical changes similar to those previously observed in other dipteran species, confirming the primary role of a genetic program for maturation and senescence of flight ability in holometabolous adult insects at the functional and underlying cellular, biochemical levels.

Actomyosin↗
PubMed1980

Usefulness of stochastic analysis of body weight as a tool in experimental aging research.

The statistical characteristics of body weight in a number of longitudinally studied mouse populations were examined. Frequency distribution of body weights appears to be rather "fluid" (though within a strict range), changing from symmetric to positively skewed to symmetric and finally to negatively skewed as the mice pass through the stages of early maturity, middle age, and senescence. Because body weight is a highly integrated physiological variable, it is postulated that various diets which affect survivorship would affect body weight frequency distribution similarly. The data from studies with an antioxidant diet and two toxic diets support this hypothesis. In general, the effects on body weight can be assessed in a relatively short time (6-9 months) after initiation of the experiment and 4-6 months before the effect of the experimental diet is manifested in the population's survivorship, thus offering an analytical tool for considerable shortening of the duration of such studies.

Adult↗
PubMed1979

Quantitative analysis of mating behavior in aging male Drosophila melanogaster.

Dynamic changes in quantitative aspects of mating behavior of the male fruit fly as its life unfolds, from eclosion through maturity (peak performance) and "physiological death" (loss of fertility followed by complete loss of ability to mate), towards actual death, have been identified in this work by observations and measurements on 28 male fruit flies of the Oregon R strain studied individually. At weekly sessions from the first day of their imaginal life until their natural death, each fly was given the opportunity to mate with up to three virgin females during a one-hour period. Length of the latency period of each accomplished mating and duration of copulation were recorded. After mating the females were allowed to lay eggs for 24 hours and the number of offspring was counted 26 days later. The period between 1 and 4 weeks of age is characterized by peak and fairly constant performance: multiple matings, short latencies, long durations of copulation, and high degree of fertility (number of offspring); then a decline sets in, in some measures slower than in others, as the flies age. Large intra- and inter-individual variabilities were, however, found which obscure possible correlations between individual measures of mating ability and length of life. At the individual level, a preliminary analysis showed a good correlation (r = 0.80 and 0.79) between life span and week of last mating (onset of impotence) or week of last fertile mating (onset of sterility). At the population level it was found that a number of measures, i.e. number of remaining maters at each age, number of remaining fertile maters and total number of matings, had an age-course similar to survivorship but anticipated it by 4--6 weeks. Other measures, such as number of multiple matings and number of offspring declined with age faster than survivorship.

Aging↗
PubMed1978

Spectrophotofluorometric and electron microscopic study of lipofuscin accumulation in the testis of aging mice.

Lipofuscin accumulation in the testis of C57BL/6J mice ranging in age from 4 to 39 mo. was investigated by spectrophotofluorometric and electron microscopic techniques. Chloroform-methanol extracts of the whole organ contained fluorescent substances which increased linearly until about 24 mo. Thereafter, no further increases could be observed. Electron microscopy showed spermatogonia which were completely free of lipofuscin, in striking contrast with both Sertoli and interstitial cells of Leydig, which, in old animals, had accumulated very large amounts of pigment. In the Sertoli cells, a process of mitochondrial vacuolation and densification was apparently linked with the genesis of lipofuscin. On the other hand, in the interstitial cells, densification of lipid droplets played a role in the formation of most pigment granules.

Aging↗
PubMed1976

Effects of high-LET particles (40A) on the brain of Drosophila melanogaster.

To investigate the effects of galactic heavy particles on nervous tissue, Drosophila melanogaster flies were exposed to 40A from the Super-HILAC accelerator at the Lawrence Berkeley Laboratory. The energy of the particles reaching the Drosophila neurons was 4-8 MeV/nucleon, and the fluence ranged from 6 X 10(4) to 8 X 10(7) particles/cm2. Thirty-five days after irrdiation at the higher fluences, extensive tissue fragmentation and cysts were found. At fluences as low as one hit/two cell bodies (about 5 X 10(6)) and one hit/90 cell bodies (about 9 X 10(4) particles/cm2 or 21 rad average dose) swelling of neuronal cytoplasm and focally fragmented membranes were noted; at fluences ranging from one hit/six to one hit/135 cell bodies, there was frequently a marked increase in glial lamellae around nerve-cell processes, which often had degenerative features. These findings support the view that single hits by heavy particles may injure nervous tissue.

Animals↗
PubMed1975

A fine structural study of degenerative changes in the dorsal column nuclei of aging mice. Lack of protection by vitamin E.

The dorsal column nuclei of young, old, and vitamin E-supplemented old mice were examined by light and electron microscopy. Evidence of neuroaxonal dystrophy (NAD) was found in young (3-mo.-old) mice and increased with age. Vitamin E, added to the diet in the amount of 0.3%, did not protect the nuclei from age-associated degeneration. The NAD was characterized by enlarged profiles containing patches of smooth reticular networks and groups of vesicles. Various stages of mitochondrial alteration, producing multivesicular bodies as intermediate stages, were found, and other unusual forms of dense bodies were also observed. Axons, synaptic terminals, and possibly glial cells were affected, and, by 23 mo. of age, a large number of nerve fibers in nucleus gracilis were dystrophic, while nucleus cuneatus was affected to a lesser extent.

Aging↗
PubMed1975

An electron microscopic investigation of age-dependent changes in the flight muscle of Musca domestica L.

The thoracic flight muscle from adult male NAIDM house flies was examined, from emergence to very old age. Thin sections stained with uranyl acetate and bismuth showed no myofibrillar or mitochondrial degeneration from 1 day to 19 days post-emergence, contrary to earlier reports. Some progressive loss in glycogen content and increase in mitochondrial size were observed for muscle from young to very old flies. However, there was no conclusive evidence of fusion of smaller mitochondria into larger ones with advancing age, despite exhaustive examination of representative sections of muscle samples of adult males of different ages.

Aging↗
PubMed1975

The effects of cosmic Particle radiation on pocket mice aboard Apollo XVII: V. Preflight studies on tolerance of pocket mice to oxygen and heat. Part I. physiological studies.

Tests were carried out on pocket mice to ascertain their tolerance to elevated oxygen pressures alone and to a combination of hyperoxta and heat in excess of that expected during the flight of the mice on Apollo XVII. the mice withstood oxygen partial pressures up to 12 pst at normal room temperature (24 degrees C, 75 degrees F) over a period of 7 days. A few mice previously exposed to increased PO2 died in the course of exposure to an oxygen pressure of 10 pst or 12 psi (517 mm or 620 mm Hg) for 13 d in ambient heat of 32 degrees C (90 degrees F). Supplemental vitamin E and physiological saline loading given prior to exposure had no apparent protective effect. The overall conclusion was that the pocket mice which were to go on Apollo XVII could readily survive the ambient atmosphere to which they would be exposed.

Adaptation, Physiological↗
PubMed1975

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: IX Results of examination of the nasal mucosa.

The olfactory epithelium, but not the nasal respiratory epithelium, of the four pocket mice (Perognathus longimembris) that survived their flight on Apollo XVII showed both diffuse alterations and numerous disseminated focal lesions. The olfactory mucosa of the mouse that died during flight was also affected, but to a minor degree insofar as could be determined. All this was in contrast to the normal appearance of the olfactory mucosa of the numerous control animals. A number of possible causes were considered: systemic or regional infection; inhaled particulate material (seed dust); by-products from the KO2 bed in aerosol or particulate form; gas contaminants originating in the flight package; volatile substances from the dead mouse; weightlessness; and cosmic ray particle radiation. Where feasible, studies were conducted in an effort to rule in or rule out some of these potentially causative factors. No definitive conclusions were reached as to the cause of the lesions in the flight mice.

Aerosols↗