Evolution of cytochrome P-450 proteins [published erratum appears in Mol Biol Evol 1988 Mar;5(2):199]

Thirty-four cytochrome P-450 sequences from one bacterial and six vertebrate species have been aligned with the aid of a computer alignment algorithm. Phylogenetic trees were constructed using the unweighted-pair-group and neighbor-joining methods. The two trees differed at only a single branch point near the base of the tree. The cytochrome P-450 superfamily of proteins clustered into eight families and contained 16 gene-duplication events. The first gene duplication occurred approximately 1,360 Myr before the present (Mybp) and gave rise to cytochrome P-450s found in two different cellular organelles, the mitochondria and the endoplasmic reticulum. Both groups utilize cholesterol or its metabolites as substrates, implying that cholesterol existed greater than 1,360 Mybp. The fourth gene duplication (approximately 900 Mybp) gave rise to the drug-metabolizing P-450s. These proteins aid in the detoxification of foreign chemicals, as opposed to the metabolism of endogenous compounds. The importance of the capacity to metabolize drugs is reflected in 11 further gene duplications occurring in this lineage. The first occurred approximately 800 Mybp and gave rise to the two major P-450 families, the phenobarbital and 3-methylcholanthrene families. An apparent increase in the rate of cytochrome P-450 evolution is noted between the bird-mammal divergence (300 Mybp) and the mammalian radiation (75 Mybp).      

Natural occurrence of aflatoxin B<Subscript>1</Subscript> in some Indonesian food and feed products in Yogyakarta in year 1998–1999

A survey was conducted between 1998–1999 to evaluate the level of aflatoxin B₁ (AfB₁) contamination in some selected Indonesian food products, mainly peanuts and peanut products for sale in supermarkets or traditional markets in Yogyakarta, Indonesia. Quantitative analysis was carried out on 118 samples using the ELISA (Enzyme-Linked Immunosorbent Assay) technique. The results indicate that (61.1%) samples were contaminated with AfB₁ at range 2.0 to 249.0 μg/kg. Approximately 50% of the baby food products analysed were contaminated with AfB₁ and the maximum level found was 7.0 μg/kg. In corn products and fermented products, AfB₁ was detected in 66.7 and 50.0% of samples, respectively. A level as high as 5.6 μg/kg of AfB₁ was found in the corn and 6.0 μg/kg in fermented product. AfB₁ was also detected in all rice products, feed products, and other processed products at levels of up to 7.0, 27.0, and 26.0 μg/kg, respectively.