Study on the chromosomal proteins of Fasciola hepatica

ABSTRACT

In attempt to investigate histone fractions and non-histones of parasites, nuclei were isolated from Fasciola hepatica by the procedure of Pogo et al. (1966). Histone fractions H1, H2a, H2b, H3 and H4 were prepared from isolated nuclei by the procedure of Johns (1964 and l967). The five histone fractions found in most tissues were also present in the Fasciola hepatica histones. These histone fractions were characterized by amino acid analysis and by polyacrylamide disc gel electrophoresis. Non-histone proteins were extracted from isolated Fasciola hepatica nuclei and separated by SDS-polyacrylamide gel electrophoresis. The results of the experiment were summarized as follows The yield of whole histone recovered was 2.47 mg per 1 g of Fasciola hepatica. The yield of DNA was 1.02 mg per gm of tissues. Consequently the DNA to histone ratio was 12.44. The relative amounts of five fractions, i.e., Hl, H2a, H2b, H3 and H4 were 19.96 percent, 26.48 percent, 29.60 percent, 12.56 percent and 14.37 percent, respectively. Amino acid analysis of the individual histone fractions showed that the over-all compositions were similar but not identical to those of corresponding fraction from calf thymus. It was found that histone H2b fraction of Fasciola hepatica contained detectable amounts of epsilon-N-monomethyllysine. No evidence for the presence of methylated lysine or other side-chain derivatives was reported on this histone fraction. In SDS-polyacrylamide disc gel, it showed that 17 protein bands of nuclear acidic protein can be identified visually.