Accumulation and distribution of lead in the archiacanthocephalan Moniliformis moniliformis from experimentally infected rats

It recently became clear that adult eo- and palaeacanthocephalans parasitiz ing fish can bioconcentrate several heavy metals to significantly higher co ncentrations than the tissues of their definitive hosts. Following this dis covery the lead accumulation of the archiacanthocephalan Moniliformis monil iformis was investigated using experimentally infected male Wistar rats of the CD-M-strain. The worms were allowed Co grow up for 4 weeks post-infecti on followed by a 3 weeks oral lead exposure of the rats. After the exposure period the rats were killed and the metal levels were determined in muscle , liver, intestine and kidney of the rats as well as in different organs of female and male acanthocephalans. Lead concentrations were found to be hig hest in female M. moniliformis followed by the kidneys of the rats. Male wo rms contained approximately the same lead concentration as the hosts' kidne ys. Lead analysis of the worms' organs revealed the highest lead concentrat ion in the eggs of female acanthocephalans, followed by the cement gland of male Worms. Whilst the lead burden of the presoma was higher than that det ected in the kidneys of the rats, the lead content of the metasoma was even lower than in the kidneys. A lead uptake of M. moniliformis from the intes tinal lumen of the host became apparent as the faeces of infected rats cont ained significantly less lead compared to the uninfected conspecifics. Thus , this study reveals that lead accumulation also occurs in archiacanthoceph alans parasitizing mammals. But the degree of metal bioconcentration is con siderably lower compared to eo- and palaeacanthocephalans in fish. Anyway, due to a lack of adequate sentinel species in terrestrial biotopes the host -parasite system rat- M. moniliformis appears to be a useful and promising bioindication system especially in urban ecosystems in temperate regions.