title: Dihydrofolate reductase and aminopterin resistance in Pneumococcus.
mesh_terms: D000630:Aminopterin / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D008040:Genetic Linkage; D005827:Genetics, Microbial; D006358:Hot Temperature; D009154:Mutation; D011995:Recombination, Genetic; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000201:enzymology*; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism*
chemical_list: D013762:Tetrahydrofolate Dehydrogenase; D000630:Aminopterin