33 In vitro studies showed that insulin and corticosteroids induce the expression of PPAR mRNA, 34 whereas TNF down-regulates the expression of PPAR
[131] [132] Species from the following genera and the following individual species are known to synthesize B 12 : Propionibacterium shermanii , Pseudomonas denitrificans , Streptomyces griseus , Acetobacterium , Aerobacter , Agrobacterium , Alcaligenes , Azotobacter , Bacillus , Clostridium , Corynebacterium , Flavobacterium , Lactobacillus , Micromonospora , Mycobacterium , Nocardia , Proteus , Rhizobium , Salmonella , Serratia , Streptococcus and Xanthomonas
Its exact connection with this pathway is still not fully understood
Studies have examined how these metabolic changes affect various cellular processes including energy metabolism and gene expression