游仆虫信息素Er-1和Er-2对四膜虫的种间作用

信息素是生物体向外释放的化学物质,在细胞及生物体中具有种内信息传递的生理学功能。信息素这一类分子广泛分布于系统发生史中,它们的特异活性在单细胞生物、昆虫以及脊椎动物中均有报道。脊椎动物中信息素的信号传输已被证实是一嗅觉依赖过程,7TM-受体被认为是信号传输过程中的信号转换器。在低等单细胞生物(例如:来可夫游仆虫)的细胞膜上存在有信息素异构体,作为信息素分子的有效结合位点而行使其功能。本研究主要探讨单细胞的信息素(Er-1和Er-2)的基础细胞生理学作用是仅限于产生该信息素的物种,还是对其它的原生动物(例如:四膜虫)或对系统发育中分类地位较高的细胞(例如:MRC5成纤维细胞或J774巨噬细胞)均具有调节活性。研究结果表明,游仆虫的两种信息素对梨形四膜虫GL的生长调节有显著不同的作用:当信息素浓度为10-11M时,Er-1具有正调控作用,而Er-2具有抑制剂的作用。这两种配体的趋化作用也有很不同:Er-1具有一种广范的化学排斥特性,而Er-2具有一个双峰的化学吸引剂的性质。计算机检测发现,与Er-2的作用不同,Er-1可略微降低被测细胞的游动速率。趋化现象的选择特性表明Er-2信息素的受体有一种“短期”的特性;而Er-1是不能选择任何亚种群的,这也支持了我们先前的研究数据,即这两种信息素在四膜虫GL内产生两种不同的信号。四膜虫对信息素特异性的反应表明四膜虫能辨别非常近似但带有微小差异的配体(如Er-1和Er-2的电荷差异)。

Interspecific effect of Er-1 and Er-2 Euplotes pheromones in Tetrahymena

Pheromones are chemicals released externally by an organism that have intraspecific messenger effects on physiological functions of the cell/organism. Molecules belonging into this group are widely distributed in phylogeny; their specific activity has been described in unicellular organisms, insects and vertebrates. Pheromonal communication in vertebrates is proved to be an olfactory-dependent process and 7TM-receptors are considered as transducers in signalling. At the lower unicellular level (e. g. Euplotes raikovi ) membrane bound forms of the pheromone isoforms are working as effective binding sites of the molecule. The present study investigated whether basic cell-physiological effects of unicellular pheromones (Er-1 and Er-2) are limited to the species producing the pheromone or they can modulate activity of other protozoa (e.g. Tetrahymena ) or phylogenetically higher ranked models (MRC5 fibroblast or J774 macrophage). Results of investigation in Tetrahymena pyriformis GL show that the growth modulator effect of the two pheromones altered significantly: at 10-11 mol/L Er-1 had a positive effect, Er-2 an inhibitory one. Chemotactic effects of the two ligands were also distinct: Er-1 had a wide range chemorepellent character, while Er-2 had a two-peak chemoattractant character.Chemotactic selection with Er-2 showed that the receptor for this pheromone has a "short-term" character; Er-1 failed to select any subpopulation which supports our previous data, that signalling of the two pheromones is endogenously diverse in T. pyriformis GL. Pheromone-specificity of the elicited response indicates that Tetrahymena can distinguish small differences between closely related ligands (e.g.charges in Er-1 and Er-2) [Acta Zoologica Sinica 52 (6): 1125 - 1132,2006].