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.

Biogenic amines in the Caenorhabditis briggsae.

Dopamine, epinephrine, norepinephrine and serotonin were demonstrated from homogenates of Caenrohabditis briggsae by two-dimensional thin layer chromotography and the identification confirmed by gas liquid chromtography. 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.

Fine structure of the esophagus of Pratylenchus penetrans.

The fine structure of the esophagus of Pratylenchus penetrans is described. The gland lobe is syncytial and contains two types of nuclei: three large nuclei with little chromatin, and more numerous smaller nuclei with large amounts of chromatin. Some of the smaller nuclei are associated only with glandular tissue, whereas others are part of nerve ceils within the esophagus. Clusters of free ribosomes, rough endoplasmic reticulum, and numerous mitochondria occur in the lobe region where the secretory granules are formed. No Golgi bodies were observed. On the basis of these observations, possible differences in the mechanism of secretory granule formation between plant-parasitic nematodes are discussed. Several other minor differences between the fine structure of other plant-parasitic nematodes previously examined and that of P. penetrans are also noted.

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.