Soils of Contrasting pH Affect the Decomposition of Buried Mammalian (Ovis aries) Skeletal Muscle Tissue

Abstract:  Little is known about the effect of edaphic conditions on the decomposition of buried mammalian tissues. To address this, we set up a replicated incubation study with three fresh soils of contrasting pH: a Podsol (acidic), a Cambisol (neutral), and a Rendzina (alkaline), in which skeletal muscle tissue (SMT) of known mass was allowed to decompose. Our results clearly demonstrated that soil type had a considerable effect on the decomposition of SMT buried in soil. Differences in the rate of decomposition were up to three times greater in the Podsol compared with the Rendzina. The rate of microbial respiration was correlated to the rate of soft tissue loss, which suggests that the decomposition of SMT is dependent on the microbial community present in the soil. Decompositional by-products caused the pH of the immediate soil environment to change, becoming more alkaline at first, before acidifying. Our results demonstrate the need for greater consideration of soil type in future taphonomic studies.     

铜对肉鸡肝细胞线粒体膜通透性及呼吸的影响

为进一步了解铜对生物体的生物学效应,选用硫酸铜作为铜源,向即时分离的肉鸡肝细胞线粒体培养液内加入终浓度分别为5、10、20μmol/L的铜(以铜计),孵育10 min后,观察肝细胞线粒体膜通透性及呼吸的变化。结果显示,铜对线粒体膜通透性转换孔有较显著的影响,造成线粒体不同程度的肿胀,表现为线粒体悬液在540 nm处的吸光值下降,且铜浓度越高,吸光值下降越明显,在孵育6 min后3种浓度的吸光值下降百分比差异显著(P<0.05)。随着铜浓度的升高,线粒体呼吸逐渐减弱,RCR、P/O、OPR均显著降低(P<0.05),这些变化可能是微量元素铜对生物机体产生毒害作用的本质原因之一。     

体位性窒息对心、肺功能影响的实验研究

通过从股静脉将漂浮导管插入肺动脉的方法 ,检测悬挂前、悬挂期间和临终阶段呼吸、肺动脉压、心输出量的变化,探讨体位性窒息对心、肺功能影响及其在死亡中所起作用。结果:(1)悬挂前呼吸频率平稳 ,悬挂期间逐渐加快 ,临终前呈无规律状态 ;(2)悬挂期间及临终时肺动脉压比悬挂前明显升高;(3)悬挂前及悬挂期间的心输出量基本平稳 ,临终时比悬挂前及悬挂期间明显下降。本研究发现 ,悬挂可致呼吸失调 ,机体缺氧 ,导致心、肺功能障碍 ,属肺性死亡。其特征为呼吸停止是原发性的 ,心跳停止是继发的。