M. Kisiel

Aging in Caenorhabditis briggsae.

Caenorhabditis briggsae was used as a model to study aging of a metazoan under gnotobiotic conditions. At higher temperatures nematodes were shorter-lived and had a shorter generation time. Nematodes moved more slowly as they aged. Physiologic aging was marked by a decreased ability to withstand osmotic stress, a possible increase in the bodys internal solute concentration, and increased sensitivity to formaldehyde. These results suggest that the ability to osmoregulate and the permeability of the body wall are altered during senescence. The interchordal hypodermis, as well as the chordal hypodermis, contained fairly abundant structures having biosynthetic activity. During aging mitochondria of the hypodermis degenerated, some areas of the thin hypodermal band thickened and lysosome-like bodies formed in the interchordal hypodermis. Changes in osmoregulatory and excretory mechanisms are probably associated with deterioration of the hypodermis organelles.

Fine Structure Changes in the Cuticle of Adult Caenorhabditis Briggsae With Age 1)

The cuticle of young, adult Caenorhabditis briggsae contains seven layers. In old nematodes fine structure changes related to aging were observed in two layers. The outer osmiophilic membrane became more defined and in a few cases separated from the external cortical layer. Also, an electron-dense material and electron-dense balls occurred within the fluid-filled layer. The possible significance of these observations is discussed.

Effects of Dna Synthesis Inhibitors On Caenorhabditis Briggsae and Turbatrix Aceti

The effects of three DNA synthesis inhibitors on axenically grown Caenorhabditis briggsae and Turbatrix aceti were evaluated. Lower dosages of aminopterin sometimes prevented vagina formation and the eggs hatched within the oviduct. Concentrations of aminopterin, 5-fluorodeoxyuridine and hydroxyurea which prevented reproduction, caused significant growth inhibition, prevented maturation past the third larval stage, and reduced longevity. A difference in physiologic state was indicated by the inability of aminopterin treated Caenorhabditis briggsae to adjust to osmotic pressures tolerated by untreated nematodes. These studies indicate the difficulties inherent in utilizing age-synchronous nematode cultures produced by the application of DNA synthesis inhibitors.

Biogenic amines in the free-living nematode caenorhabditis briggsae

Abstract Dopamine, epinephrine, norepinephrine and serotonin were demonstrated from homogenates of Caenorhabditis briggsae by two-dimensional thin layer chromatography and the identifications confirmed by gas liquid chromatography. In Vitro studies with 14C precursors of these biogenic amines demonstrate the ability of C. briggsae to synthesize each compound. The results provide required preliminary data for studying the neurophysiology of aging utilizing the nematode as a model.

Age-related increase of cuticle permeability in the nematode Caenorhabditis briggsae.

The external cuticular surface of nematodes, which resembles cellular membranes in certain ways, appears to deteriorate with age. For example, when the permeabilities to radioactive water of young and old nematodes were compared, and the data were corrected for the different surface: volume ratios, the older nematodes were significantly more permeable. In both living and dead nematodes, the same rates of water exchange were observed, indicating that the major route of exchange was probably by passive diffusion through the cuticle rather than by active processes such as swallowing or excreting water.

Studies on ageing in Turbatrix aceti

Morphologic and physiologic changes which occur during senescence in the free-living nematode Turbatrix aceti are described. With age areas of the interchordal hypodermis containing nerve elements thickened, electron-dense aggregates formed within the pseudocoelom and age pigment granules accumulated within the intestinal epithelium. Specific gravity did not change with age. Old nematodes which had reproduced showed increased osmotic fragility, but this change was not observed in virgin females. The parameters characterizing senescence in T. aceti are compared with those of Caenorhabditis briggsae, another nematode being used as a model to study biological ageing.

Caenorhabditis briggsae: Effects of aminopterin

Abstract The characteristic features of senescence developed prematurely in Caenorhabditis briggsae treated with the DNA synthesis inhibitor aminopterin at the minimum dosage which inhibits gonad formation. In addition, aminopterin induced other changes which thus far have not been associated with normal aging of C. briggsae . Interpretations of these results are given based on current knowledge of the mode action of aminopterin and an extant theory of aging.

Surface Scanning Observations of Changes in Caenorhabditis Briggsae During Aging

SEM observations of adult Caenorhabditis briggsae females showed differences between young and old nematodes. In young nematodes the cuticle was generally smooth, whereas in old ones it was wrinkled. Deirids were located at the level of the excretory pore in the lateral field. They were distinct in young nematodes but indistinct in old ones. The oral opening was formed by six lips, which were closed in old nematodes and open in young ones. The vulva possessed two semi-circular lips and was bordered by two lateral flaps. These lips were smooth in young specimens and wrinkled in old ones. Cryofractures of old nematodes showed cavities in the intestinal epithelium corresponding to areas in which age pigment granules normally occur. No such cavities were seen in young nematodes.

Studies On the Effects of Two Procaine Preparations On Caenorhabditis Briggsae

Concentrations below 0.36 mM procaine had no significant effect on several developmental parameters of Caenorhabditis briggsae; growth, fecundity, time of inception of the reproductive period and duration of the reproductive period. In old C. briggsae, significant differences in osmotic fragility occurred to concentrations as low as 0.18 mM. Using cationized ferritin for evaluating membrane negative surface charge, at 33 mM partial lysis of the cuticle surface membrane occurred and negative charge was lost from unlysed areas. At 7.2 mM the negative charge was present in some areas of the membrane but not in others, while at 0.18 mM negative charge density did not differ significantly from that of untreated nematodes. Since the osmotic fragility effect persisted at procaine concentrations which did not affect surface charge, these results suggest two separate modes of action of procaine on membranes.

Studies On Aging of Turbatrix Aceti

Turbatrix aceti mated at day 7 after hatch, started to reproduce on day 8 and reproduction lasted for 11 days. When mating was delayed by segregating individual nematodes, the older the nematodes at mating, the longer the elapsed time prior to the start of reproduction and the shorter the reproductive period. Mating of progressively older females with young males or progressively older males with young females showed the degeneration of gonad function with age and demonstrated that the effects of aging of either the male or female gonad on reproduction are similar.