Effect of vitamin B12 and folate on biosynthesis of methionine from homocysteine in the nematode Caenorhabditis briggsae.
(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.
D000818:Animals; D002794:Choline / Q000494:pharmacology; D005492:Folic Acid / Q000494:pharmacology*; D006710:Homocysteine / Q000378:metabolism; D008715:Methionine / Q000096:biosynthesis*; D009348:Nematoda / Q000254:growth & development / Q000378:metabolism*; D014805:Vitamin B 12 / Q000494:pharmacology*
D006710:Homocysteine; D005492:Folic Acid; D008715:Methionine; D002794:Choline; D014805:Vitamin B 12