Studies on the Structure and Function of Autotomy Promoting Factor in Sea Stars

据了解，生活在日本沿海地区的几种小行星，如Asterias amurens、Coscinasterias acutispina、Distolasterias nippon和Aphelasterias Japan，在受到捕食者攻击或手臂受伤时会截断手臂。这种现象被称为自体切割，同样的过程可以通过物理、电击或热休克来人工产生。通过人工自体切开获得的体液，在注射到体腔中时，可以促进同一物种的手臂截肢。这种液体中的物质被命名为自切促进因子(APF)，但APF的化学结构尚未阐明。在本研究中，我们研究了自体切断的生物学过程和APF的结构。将热休克获得的体液注射到同一物种中，观察到注射的手臂被截断。本研究采用生物测定法。东京湾的山杨比木通湾的山杨更敏感。自体切断始于腹侧的软化，同时在自体切断平面上收缩并分离出活动板间的肌肉。然后用管脚将注射的手臂固定在底部，其余的四只手臂向相反的方向移动，撕下注射的手臂。利用东京湾采集的烫伤的山艾虫体液研究APF的分离。体液用大小排斥柱分离，然后重复高效液相色谱法。有一组分检测到自体切割的促进作用，呈单峰。这种物质是一种极其微小的成分，为了获得足够的量来测量^1H和^&lt；13&gt；C核磁共振谱，多次重复进行了高效液相色谱分离。虽然最终的结构仍在鉴定中，但这种物质被发现是烟酰胺的衍生物。

A few species of asteroids living in the coast area of Japan, such as Asterias amurensis, Coscinasterias acutispina, Distolasterias nippon and Aphelasterias japonica, are known to amputate their arms when they are attacked by predators or physically wounded on arms. This phenomenon is called autotomy, and the same process can be artificially generated by physical, electric or thermal shock. The body fluid, obtained by the artificial autotomy, promoted the amputation of an arm of the same species when injected in a coelom. The substance in this fluid was named as autotomy promoting factor (APF), but the chemical structure of APF has not been elucidated. In this study, we investigated the biological process of autotomy and structure of APF.Body fluids obtained by thermal shock were injected in the same species and observed an amputation of the injected arms. This bioassay was used for the study. A. amurensis of Tokyo Bay were more sensitive than those of Mutsu Bay. Autotomy began with softening of aboral side, and simultaneously, the muscles between ambulacral plates were contracted and separated at the autotomy plane. The injected arm was then settled on the bottom by tube feet and the rest of four arms moved toward the opposite direction to tear off the injected arm.Isolation of APF was studied using scalded body fluids of A. amurensis collected in Tokyo Bay. Body fluids were separated by a size exclusion column followed by repeated HPLC. Promotion of autotomy was detected for one fraction, which showed a single peak. This substance is an extremely minor component, and HPLC separation was repeated many times to obtain enough amounts to measure the ^1H and ^<13>C NMR spectra. Although the final structure is still under identification, this substance is revealed to be a derivative of nicotinamide.