In vitro protein synthesis in Hymenolepis diminuta, a rat intestinal cestode

Helminth parasitic infestations are of great concern to the health of man and other animals. Limited studies have been carried out on the process of protein synthesis which, apart from having academic importance, could possibly provide a target for drug attack. In the present study distribution pattern of newly synthesized proteins in Hymenolepis diminuta, a rat intestinal cestode, has been worked out. The worms absorbed and incorporated about 21% and 3.8% of the amino acids added to the incubation medium, respectively. In other words, 18.3% of the absorbed amino acids was incorporated into proteins. Absorbed amino acids were distributed between washed cell debris (unbroken cells, nuclei, etc.) and crude extract in a ratio of 1:12. Cytosolic, microsomal and mitochondrial fractions received 72%, 3.2% and 6.6% amino acids, respectively. The mitochondrial membranes and the matrix shared equally the absorbed amino acids. The distribution pattern of amino acid incorporation was, however, different from that of absorption. The incorporation ratio between washed cell debris and crude extract was 1:3.7. The cytosolic, microsomal and mitochondrial fractions received 32.8%, 8.6% and 18.4% of the incorporated amino acids, respectively. Within mitochondria incorporation was more in membranes than in the matrix. The ratios of incorporated versus free-pool amino acids in different fractions varied widely from 1:0.54 to 1:11.