Mapping chemical gradients within and along a fibrous structural tissue, mussel byssal threads
Mapping chemical gradients within and along a fibrous structural tissue, mussel byssal threads
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DOI：
10.1074/jbc.m508674200
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发表时间：
2005-11-25
影响因子：
4.8
通讯作者：
Waite, JH
中科院分区：
文献类型：
--
作者：
Sun, CJ;Waite, JH
贻贝的贝丝是一种器官外结缔组织，在机械性能方面表现出惊人的端到端梯度，从而为研究梯度是如何形成的提供了独特的机会。Mfp-1（贻贝足蛋白-1）是深海丝的保护性外角质层的显著组分，因为其高的3，4-二羟基苯丙氨酸（多巴）含量为10- 15mol%。mfp-1提取的连续脚部分的贻贝galloprovincialis的氨基酸分析揭示了一个post-acidtionally介导的梯度与最高的多巴水平存在于mfp-1从附属腺附近的脚的尖端逐渐减少向基地。多巴含量的连续段的深海线程减少从远端到近端，从而反映了mfp-1的脚的趋势。电感耦合等离子体分析表明，某些金属离子，包括铁遵循多巴沿着线程的趋势。能量色散X射线光谱分析表明，铁，当存在时，集中在角质层的线程，但稀疏的核心。轴向铁梯度似乎与多巴梯度最密切相关。贻贝和深海丝在Fe 3+补充海水中的直接孵化表明，深海丝不能从海水中螯合铁。相反，颗粒/可溶性铁是积极采取的贻贝在过滤器喂养和纳入深海线程在其分泌过程中。我们的研究结果表明，贻贝可能利用多巴和金属之间的相互作用，以定制特定的机械性能线程的不同部分。
The byssal thread of a mussel is an extraorganismic connective tissue that exhibits a striking end-to-end gradient in mechanical properties and thus provides a unique opportunity for studying how gradients are made. Mfp-1 ( Mytilus foot protein-1) is a conspicuous component of the protective outer cuticle of byssal threads given its high 3,4-dihydroxyphenylalanine ( Dopa) content at 10-15 mol%. Amino acid analysis of mfp-1 extracted from successive foot sections of Mytilus galloprovincialis reveals a post-translationally mediated gradient with highest Dopa levels present in mfp-1 from the accessory gland near the tip of the foot decreasing gradually toward the base. The Dopa content of successive segments of byssal threads decreases from the distal to the proximal end and thus reflects the trend of mfp-1 in the foot. Inductively coupled plasma analysis indicates that certain metal ions including iron follow the trend in Dopa along the thread. Energy-dispersive x-ray spectrometry showed that iron, when present, was concentrated in the cuticle of the threads but sparse in the core. The axial iron gradient appears most closely correlated with the Dopa gradient. The direct incubation of mussels and byssal threads in Fe3+ supplemented seawater showed that byssal threads are unable to sequester iron from the seawater. Instead, particulate/soluble iron is actively taken up by mussels during filter feeding and incorporated into byssal threads during their secretion. Our results suggest that mussels may exploit the interplay between Dopa and metals to tailor the different parts of threads for specific mechanical properties.