Department of Chemical Biology, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China.
Environ Toxicol Pharmacol. 2006 Sep;22(2):121-7. doi: 10.1016/j.etap.2005.12.011. Epub 2006 Mar 6.
Tetrahymena thermophila BF(5) produce heat by metabolism and movement. Using a TAM air isothermal microcalorimeter, the power-time curves of the metabolism of T. thermophila BF(5) during growth were obtained and the action on them by the addition of Cr(VI) were studied. The morphological change with Cr(VI) coexisted and biomass change during the process of T. thermophila BF(5) growth were studied by light microscope. Chromium has been regarded as an essential trace element for life. However, hexavalent chromium is a known carcinogen, mutagen, cytotoxicant and strong oxidizing agent. Cr(VI) of different concentration have different effects on T. thermophila BF(5) growth with the phenomenon of low dose stimulation (0-3×10(-5)molL(-1)) and high dose inhibition (3×10(-5) to 2.4×10(-4)molL(-1)). The relationship between the growth rate constant (k) and c is a typical U-shaped curve, which is a characteristic of hormesis. T. thermophila BF(5) cannot grow at all when the concentration of Cr(VI) is up to 2.4×10(-4)molL(-1). The microscopic observations agree well with the results obtained by means of microcalorimetry. And T. thermophila BF(5) had obviously morphological changes by the addition of Cr(VI).
嗜热四膜虫 BF(5) 通过代谢和运动产生热量。使用 TAM 空气等温微量热计，获得了嗜热四膜虫 BF(5)在生长过程中的代谢功率-时间曲线，并研究了 Cr(VI)对其的作用。通过光镜研究了 Cr(VI)共存时的形态变化和嗜热四膜虫 BF(5)生长过程中的生物量变化。铬被认为是生命必需的微量元素。然而，六价铬是一种已知的致癌物质、诱变剂、细胞毒性物质和强氧化剂。不同浓度的 Cr(VI)对嗜热四膜虫 BF(5)的生长有不同的影响，表现为低剂量刺激（0-3×10(-5)molL(-1))和高剂量抑制（3×10(-5)至 2.4×10(-4)molL(-1))。生长速率常数 (k) 与 c 之间的关系是典型的 U 形曲线，这是一种激素作用的特征。当 Cr(VI)的浓度达到 2.4×10(-4)molL(-1)时，嗜热四膜虫 BF(5)根本无法生长。显微镜观察结果与微量热计获得的结果非常吻合。并且 Cr(VI)的添加使嗜热四膜虫 BF(5)发生了明显的形态变化。
