Nelson Mandela Metropolitan University, Coastal and Marine Research, South Campus, University Way, Port Elizabeth, 6001, South Africa.
University of KwaZulu-Natal, Life Sciences, Westville Campus, Durban 4000, South Africa.
Sci Rep. 2017 Mar 27;7:45162. doi: 10.1038/srep45162.
Feathers do not have to be especially strong but they do need to be stiff and at the same time resilient and to have a high work of fracture. Syncitial barbule fibres are the highest size-class of continuous filaments in the cortex of the rachis of the feather. However, the rachis can be treated as a generalized cone of rapidly diminishing volume. This means that hundreds of syncitial barbule fibres of the rachis may have to be terminated before reaching the tip - creating potentially thousands of inherently fatal crack-like defects. Here I report a new microstructural architecture of the feather cortex in which most syncitial barbule fibres deviate to the right and left edges of the feather rachis from far within its borders and extend into the barbs, side branches of the rachis, as continuous filaments. This novel morphology adds significantly to knowledge of β-keratin self-assembly in the feather and helps solve the potential problem of fatal crack-like defects in the rachidial cortex. Furthermore, this new complexity, consistent with biology's robust multi-functionality, solves two biomechanical problems at a stroke. Feather barbs deeply 'rooted' within the rachis are also able to better withstand the aerodynamic forces to which they are subjected.
羽毛不必特别强壮，但需要坚硬、同时具有弹性，并具有较高的断裂功。合胞羽小枝纤维是羽轴皮质中连续长丝的最高尺寸级。然而，羽轴可以被视为一个体积迅速减小的广义圆锥体。这意味着数百根羽轴的合胞羽小枝纤维可能必须在到达尖端之前终止，从而产生数千个潜在的致命裂纹状缺陷。在这里，我报告了一种新的羽毛皮质微观结构，其中大多数合胞羽小枝纤维从羽轴的边界内部向羽轴的左右边缘偏离，并延伸到羽轴的羽枝、侧枝中，作为连续长丝。这种新的形态结构显著增加了对羽毛中β-角蛋白自组装的了解，并有助于解决羽轴皮质中潜在的致命裂纹状缺陷问题。此外，这种新的复杂性与生物学的稳健多功能性一致，一次性解决了两个生物力学问题。深深地“扎根”在羽轴内的羽枝也能够更好地承受它们所承受的空气动力。
