RESUMO
The free-living, hermaphroditic nematode Caenorhabditis briggsae has a nutritional requirement for sterols. It will reproduce indefinitely in a liquid medium containing only bacterial cells (Escherichia coli) and salts if various sterols are present. Several other lipid-soluble materials are ineffective in supporting reproduction.
Assuntos
Nematoides/metabolismo , Reprodução , Esteróis/metabolismo , Animais , Meios de Cultura , Transtornos do Desenvolvimento Sexual , Escherichia coli , Vitamina D/metabolismoRESUMO
The free-living hermaphroditic nematode Caernorhabditis briggsae has a nutritional requirement for heme. The organism can be subcultured repeatedly in a chemically defined axenic medium that contains autoclaved bacterial cells (Escherichia coli) and sterols if a hemeprotein-containing fraction from liver is present. Pure myoglobin, hemoglobin, cytochrome c, and hemin, respectively, can substitute effectively for the liver fraction.
Assuntos
Heme/farmacologia , Nematoides/crescimento & desenvolvimento , Reprodução/efeitos dos fármacos , Animais , Meios de Cultura , Citocromos/farmacologia , Hemoglobinas/farmacologia , Fígado , Mioglobina/farmacologia , Extratos de Tecidos/farmacologiaRESUMO
Ellsworth Dougherty (1921-1965) was a man of impressive intellectual dimensions and interests; in a relatively short career he contributed enormously as researcher and scholar to the biological knowledge base for selection of Caenorhabditis elegans as a model organism in neurobiology, genetics, and molecular biology. He helped guide the choice of strains that were eventually used, and, in particular, he developed the methodology and understanding for the nutrition and axenic culture of nematodes and other organisms. Dougherty insisted upon a concise terminology for culture techniques and coined descriptive neologisms that were justified by their linguistic roots. Among other contributions, he refined the classification system for the Protista.
Assuntos
Caenorhabditis elegans/genética , Genética/história , Modelos Animais , Animais , História do Século XX , Estados UnidosRESUMO
(i) Omission of L-methionine from the medium resulted in an 80% population reduction. Substitution of D,L-homocysteine corrected methionine deficiency in C. briggsae in the presence of supraoptimal vitamin B12 and folic acid. (ii) An absolute vitamin B12 requirement in C. briggsae developed in the medium containing homocysteine at the second subculture. Concentration of 6 ng/ml of vitamin B12 (at 100 ng/ml of folic acid) was sufficient to support maximum growth of C. briggsae in the medium containing homocysteine. (iii) It was found that either supraoptimal folic acid (2000 ng/ml) or supraoptimal vitamin B12 (3750 ng/ml), with homocysteine, supported very little population growth of C. briggsae. However, supraoptimal folic acid and supraoptimal vitamin B12 together supported a maximum population growth. Therefore, it was concluded that both vitamin B12 and folic acid were required for the biosynthesis of methionine from homocysteine. Studies also showed that the two vitamins spared each other for population growth in the medium containing homocysteine.