RESUMO
The objective of this study was to evaluate the molecular characteristics of heat shock protein 70 (HSP70) gene, and document changes in HSP70 gene expression upon exposure of Perinereis aibuhitensis to aqueous Cu2+. Full length cDNA of HSP70 was sequenced and the characteristics of the translated protein were determined and compared both with other ragworms species and other invertebrates. The results showed that the cDNA was 2161 bp and consisted of a 5'-terminal untranslated region (UTR) of 48 bp, a 3'-termianl UTR of 142 bp with a canonical polyadenylation signal sequence AATAAA and a poly A tail, and an open reading frame (ORF) of 1971 bp. The HSP70 protein was 656 amino acids with a calculated molecular weight of 71.43 kD and theore-tical isoelectric point of 5.15. Sequence analysis of the protein showed that HSP70 of P. aibuhitensis contained three signature sequences IDLGTTYS, IFDLGGGTFDVSIL and IVLVGGSTRIPKIQK all belonging to the HSP70 family, a cytoplasm characteristic motif of EEVD, and the C-terminal repeats of GGMP. The molecular characteristics of P. aibuhitensis shared 94% identity with other ragworms and 79% identity with other invertebrates. In ragworms exposed to Cu2+, expression of HSP70 mRNA increased significantly with Cu2+ concentration (0.2-5.0 mg·L-1), and it reached the peak on 1-day exposure. In summary, the molecular characteristics of HSP70 of P. aibuhitensis were described, and its gene expression was inducible by exposure to aqueous Cu2+, suggesting HSP70 has potential to become a useful molecular biomarker of environmental pollution.
Assuntos
Proteínas de Choque Térmico HSP70/genética , Poliquetos/genética , Sequência de Aminoácidos , Animais , Clonagem Molecular , DNA Complementar , Filogenia , RNA MensageiroRESUMO
Ragworm (Polychaeta) is an ecologically important species in intertidal mudflats and estuaries and is recognized as a sentinel species for environmental monitoring. In the intertidal belt of China, the ragworm Perinereis aibuhitensis is frequently exposed to various toxicants including cadmium (Cd) and petroleum hydrocarbons (PHCs). The present study investigated the influence of PHCs on accumulation of Cd and the induction of metallothionein (MT) in P. aibuhitensis by means of chronic microcosm experiment in which the ragworms were exposed to Cd or combinations of Cd and PHCs. The accumulation of Cd in P. aibuhitensis increased significantly with the Cd exposure concentration when exposed to Cd alone. Further, the bioconcentration factors (BCFs) for Cd in P. aibuhitensis increased with the duration of exposure. The addition of PHCs in Cd exposure solutions significantly increased the accumulation of Cd in P. aibuhitensis, compared with the control. Exposure to Cd induced the expression of MT, and the expression increased with the concen- tration up to 180 mg · kg(-1) DM Cd at which point the level of induction did not increase. PHCs without Cd did not significantly induce MT in P. aibuhitensis, but the addition of PHCs with Cd did influence the induction of MT compared to Cd without PHCs. Results indicated that PHCs could modulate the expression of MT during co-exposure with Cd. The potential substances other than metals influencing the interpretation of MT expression in wild P. aibuhitensis must be recognized when MT is used as a monitoring index.
