节肢动物肠道及腹神经索的降解实验

Experimental taphonomy on the degradation of guts and ventral nerve cords of arthropods

节肢动物的内部器官组织,如消化系统和神经系统等精细结构在寒武纪化石中的保存特征对探索早期生命和地球环境的演化具有重要意义。近年来,其原始形态与保存机理被广泛讨论,说明此类型软躯体组织的保存行为还需多方面的实验和理论探索。实验埋藏学作为埋藏学的分支,为解释生物化石化过程中解剖结构的变化及相应特异埋藏化石库的形成提供了重要理论支撑和实验技术手段。本文以节肢动物南美白对虾的肠道和腹神经索为材料,在不同温度及组合条件下进行埋藏学实验,以观察此类生物软组织的降解过程。实验结果显示,肠道和腹神经索在不同温度下的降解趋势相似,但降解速率不同:肠道和腹神经索在25℃条件下的降解速率和降解程度明显大于其在10℃条件。同一温度条件下,肠道与腹神经索的降解程度存在早期差异;10℃条件下,反应产生的微生物膜形态及规模有所不同,肠道-腹神经索组合产生的微生物膜规模远大于肠道、腹神经索的单独处理组,且难以辨认。由此可见,温度是影响肠道和腹神经索降解速度和程度的重要因素。此外,微生物在生物内部器官组织降解过程中起到了重要的生化作用。生物器官组织的降解过程,以及不同条件下微生物膜的形成对化石的形态特征尤其是内部精细结构的保存解释具有重要影响。

The delicate internal organs of the Cambrian arthropods,such as the digestive and nervous systems,provide significant insights into the evolution of early life and the Cambrian ecosystems.As such,their original morphology and preservation mechanisms have been the focus of research in recent years,indicating that the exploration on the preservation mechanisms of soft tissues requires a variety of textural experiments and theories.As a branch of taphonomy,the experimental taphonomy provides important theoretical supports and empirical means for interpreting anatomical structures during fossilization of dead bodies and the formation of a Lagerst?tte.We present this experimental means on the guts and ventral nerve cords of the arthropod Penaeus vannamei under different temperatures and combined conditions in order to observe the degradation process of these soft tissues.The result shows that the degradation trends of guts and ventral nerve cords are similar at different temperatures,but at different rates.The rate and degree of degradations of gut and ventral nerve cord materials at 25℃are significantly higher than those at 10℃.At the same temperature,the degradations of guts and ventral nerve cords are different in the early stage.The morphology and the amount of biofilms produced by the degradation at 10℃are totally different.The amount of biofilms produced by the combination of guts and ventral nerve cords is much higher than those produced separately by guts and ventral nerve cords.It is also difficult to distinguish the biofilms produced by the guts and ventral nerve cords.Therefore,temperature is an important factor affecting the speed and degree of gut and ventral nerve cord degradation.In addition,microorganisms play an important biochemical role during the degradation process of biological organs and tissues.The degradation process of biological organs and tissues,associated with the formation of biofilm,has a great influence on the morphological characteristics of fossils,especially the preservation and interpretation of delicate internal structures.