Uptake and Excretion of Amino Acids and Utilization of Glucose by Schistosoma Japonicum Eggs

Abstract

SUMMARY: The utilization of amino acids and glucose in the external nutrients and the excretion of nitrogenous compounds by Schistosoma japonicum eggs were investigated with the eggs cultured in a chemically defined medium (MEMSE-J). Of the 15 amino acids in MEMSE-J, arginine and glutamine markedly decreased in concentration during cultivation of S. japonicum eggs. The nitrogenous excretory products of developing eggs were demonstrated to be at least four amino acids (alanine, proline, glutamic acid and ornithine), urea and ammonia. Glucose was consumed at an estimated rate of 32 ng/living egg/day during the period of egg growth and differentiation. When 14C-labelled glucose was included in the culture medium, the radioactivity was incorporated into three amino acids (alanine, proline and glutamic acid), which were excreted by Sm japonicum eggs. The results were discussed with reference to the possible role in stimulating fibrosis in the granuloma of schistosomiasis.

Comparative real-time PCR and enzyme analysis of selected gender-associated molecules inSchistosoma japonicum

“…The up-regulation of Contig 8420 (arginase) in females compared with males by microarray analysis (Table 1) and real-time PCR (Table 3) shown here was not confirmed by enzyme activity measurements of SJC extracts, which suggests the presence and activity of multiple types of the gene. The presence of multiple forms of this gene is also supported by the low copy/reaction number shown in SJC eggs (Table 3), as previous studies have suggested that ornithine is a nitrogenous excretory product of this life-cycle stage (Kawanaka et al 1986). Further protein sequence analysis and expression data together with a detailed study of this enzyme in S. japonicum may provide an explanation of the observed differential expression among the males, females and eggs of S. japonicum.…”

“…Although the SjARG gene has been identified in adult S. japonicum (Li et al . 2006) and ornithine production has been reported in this species (Kawanaka et al . 1986; Fan et al .…”

“…In mammals, 2 arginase genes, types I and II, have been identified ; type I occurs in liver cells and type II has a wide tissue distribution. Although the SjARG gene has been identified in adult S. japonicum (Li et al 2006) and ornithine production has been reported in this species (Kawanaka et al 1986 ;Fan et al 2002) and S. mansoni (Cesari et al 2000), the arginase enzyme has not been studied in schistosomes in any detail. The up-regulation of Contig 8420 (arginase) in females compared with males by microarray analysis (Table 1) and real-time PCR (Table 3) shown here was not confirmed by enzyme activity measurements of SJC extracts, which suggests the presence and activity of multiple types of the gene.…”