Worm Breeder's Gazette 3(1): 22
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The principal aim of our study using nematode is to analyze the aging phenomenon taking the animal as an model system. The strain which we are using now is identified as Rhabditis sp. which was isolated from a rice farm near our school in 1975. Like C. elegans, it is free-living, but , contrary to the former, it is dioecious, a property, we think, which is more suitable for the study of aging since a synchronous culture is available without any pretreatment for preventing reproduction (sex ratio: female to male is 16:1 ). The size of our worm is somewhat smaller than that of C. elegans ( male, 580 m female, 830 m). It can grow and reproduce by nearly the same way as in the case of C. elegans.Life cycle: At 20 C, eggs hatch to yield larvae after about 24 hours and the latter comes to maturity in five days. A female lays 100 eggs once during her life span and it can survive thereafter, although the average life span seems to be shorter than in the case of virgin female.In some cases, very old females (for example, 100 days old) can lay egg; with the same number and hatchability as the eggs from young female. Age versus survival: Virgin females gave a typical sigmoidal survival curve. At 20 C and 25 C, survival begins to decrease at about 60th day from hatching and in an experiment the maximum and average life span was estimated to be about 190 and 90 days, respectively. At 30 C, the decrease in survival began earlier (at about 40th day). X-irradiation at 4 krads had no effect on the mortality curve. At 35 C, eggs can hatch perfectly, but females cannot lay eggs. We are now performing experiments to get knowledges for male worms and to examine factors influencing age-related mortality including radiations and chemicals. All of the above knowledges may be needed as the basis to go into the study on molecular level. In these experiments, worms are cultivated in a small volume of buffer put on an agar layer in a small petri dish. E. coli cells are given as food.