IDENTIFICATION OF HEAVY-METAL INDUCED CHANGES IN THE EXPRESSION PATTERNS OF THE TRANSLATIONALLY CONTROLLED TUMOR PROTEIN (TCTP) IN THE EARTHWORM LUMBRICUS-RUBELLUS

Heavy metal contaminated soils are assessed for specific human health and ecological risk by governmental regulatory agencies utilizing the abundant soil invertebrate, the earthworm, in a biomonitoring process. Fingerprinting the molecular genetic responses resulting from heavy m etal exposure facilitates the identification of biomarkers for assessi ng the impact of such pollution on individual organisms. This paper re ports the identification of a novel translationally controlled tumour protein (TCTP) in the earthworm Lumbricus rubellus. In addition to the standard molecular biological technique of differential Southern blot ting, a fully quantitative approach (fluorescent microvolume PCR) was performed to assess the specific expression profiles of TCTP in earthw orms exposed to different heavy metal regimes. After normalizing with actin as an invariant control, the results showed that TCTP was upregu lated by at least a factor of 4 in the population originating from a P b/Zn/Cd polluted mine, compared to an unpolluted control population. A n even more pronounced increase was identified in earthworms native to a Cu polluted mine, where TCTP increased 335-fold. TCTP copies in ear thworms exposed to artificial soil with a single stressor (Cd) were 14 times higher than in the appropriate control earthworms (maintained o n artificial soil without Cd). The data presented are novel in two way s: first, they provide evidence for an upregulation that is induced by heavy metals (especially copper); second, they show that TCTP can als o be under transcriptional control, therefore upregulation is not limi ted to translational modifications as TCTP's nomenclature suggests. (C ) 1998 Elsevier Science B.V. All rights reserved.