Sweeting C J, Polunin N V C, Jennings S
School of Marine Science and Technology, University of Newcastle, Newcastle Upon Tyne NE1 7RU, UK.
Rapid Commun Mass Spectrom. 2004;18(21):2587-92. doi: 10.1002/rcm.1661.
Carbon and nitrogen stable isotope analyses are routinely used to investigate aquatic food webs, and have potential application in retrospective investigations using archived materials. However, such analyses assume that storage does not alter isotopic signatures of materials preserved, or that changes in isotopic composition during storage are predictable. Here we examine preservation shifts on cod (Gadus morhua) muscle, roe and liver tissue over 21 months following preservation in 80% ethanol, in 4% formaldehyde, and by freezing. Preservation shifts were not consistent among tissues. High protein tissues exhibited greater delta(15)N shifts than low protein tissues in 4% formaldehyde, while greater delta(13)C shifts occurred in relatively higher fat tissues when preserved in alcohol. Freezing did not change isotopic signatures. Responses of delta(15)N and delta(13)C are explained by differences in the preservative's isotopic signature and the reaction properties and biochemical composition of the tissues preserved. The results clarify some of the processes that lead to isotopic change during preservation.
碳和氮稳定同位素分析通常用于研究水生食物网，并且在利用存档材料进行回顾性调查中具有潜在应用价值。然而，此类分析假定储存不会改变所保存材料的同位素特征，或者假定储存期间同位素组成的变化是可预测的。在此，我们研究了鳕鱼（大西洋鳕）的肌肉、鱼卵和肝脏组织在分别保存在80%乙醇、4%甲醛中以及冷冻保存21个月后的保存变化。不同组织间的保存变化并不一致。在4%甲醛中，高蛋白组织比低蛋白组织表现出更大的δ(15)N变化，而保存在酒精中时，相对高脂肪组织出现更大的δ(13)C变化。冷冻未改变同位素特征。δ(15)N和δ(13)C的变化可通过防腐剂的同位素特征以及所保存组织的反应特性和生化组成差异来解释。这些结果阐明了一些导致保存期间同位素变化的过程。
