[
Exp Gerontol,
1975]
A technique is described for the continuous growth of an age-synchronized population of Caenrohabditis elegans. After initial isolation of newly hatched individuals from a mixed age culture, synchrony through the reproductive phase was sufficiently well maintained to ensure that over 90% of the post-reproductive population belonged to the original generation. The technique is based on culturing the nematodes on the upper surface of a fine stainless steel mesh through which only larvae, but not adults, are small enough to burrow. It largely overcomes serious disadvantages of the two previously used methods for maintaining synchrony which were based on the use of inhibitors or the manipulation of individual worms. Supplementary techniques are described for the handling and initial synchronization of the worms which are cultured in a sterile completely defined medium. General features of the development and senescence of the worms under our conditions are reported. Mean life span (50% survival) was approx. 58 days and maximum longevity in excess of 80 days. Reproduction lasted from the 5th to about the 26th day of age and its termination coincided with a short period of high mortality. Growth in size of the worms ceased during the reproductive period but recommenced for about 25 days in worms surviving the post-reproductive mortality.
[
Water Res,
2009]
Nematodes, which occur abundantly in granular media filters of drinking water treatment plants and in distribution systems, can ingest and transport pathogenic bacteria and provide them protection against chemical disinfectants. However, protection against UV disinfection had not been investigated to date. In this study, Caenorhabditis elegans nematodes (wild-type strain N2) were allowed to feed on Escherichia coli OP50 and Bacillus subtilis spores before being exposed to 5 and 40 mJ/cm(2) UV fluences, using a collimated beam apparatus (LP, 254 nm). Sonication (15 W, 60s) was used to extract bacteria from nematode guts following UV exposure in order to assess the amount of ingested bacteria that resisted the UV treatment using a standard culture method. Bacteria located inside the gut of C. elegans were shown to benefit from a significant protection against UV. Approximately 15% of the applied UV fluence of 40 mJ/cm(2) (as typically used in WTP) was found to reach the bacteria located inside nematode guts based on the inactivation of recovered bacteria (2.7 log reduction of E. coli bacteria and 0.7 log reduction of B. subtilis spores at 40 mJ/cm(2)). To our knowledge, this study is the first demonstration of the protection effect of bacterial internalization by higher organisms against UV treatment, using the specific case of E. coli and B. subtilis spores ingested by C. elegans.