State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China.
State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Engineering and Technology Research Center for Novel Silk Materials, Chongqing 400716, China.
Biochim Biophys Acta Gen Subj. 2018 May;1862(5):1148-1156. doi: 10.1016/j.bbagen.2018.02.007. Epub 2018 Feb 13.
Bombyx mori silk fibers with thin diameters have advantages of lightness and crease-resistance. Many studies have used anti-juvenile hormones to induce trimolters in order to generate thin silk; however, there has been comparatively little analysis of the morphology, structure and mechanical properties of trimolter silk.
This study induced two kinds of trimolters by appling topically anti-juvenile hormones and obtained thin diameter silk. Scanning electron microscope (SEM), FTIR analysis, tensile mechanical testing, chitin staining were used to reveal that the morphology, conformation and mechanical property of the trimolter silk.
Cocoon of trimolters were highly densely packed by thinner fibers and thus had small apertures. We found that the conformation of trimolter silk fibroin changed and formed more β-sheet structures. In addition, analysis of mechanical parameters yielded a higher Young's modulus and strength in trimolter silk than in the control. By chitin staining of silk gland, we postulated that the mechanical properties of trimolters' silk was enhanced greatly during to the structural changes of silk gland.
We induced trimolters by anti-juvenile hormones and the resulting cocoons were more closely packed and had smaller silk fiber diameters. We found that the conformation of trimolters silk fibroin had a higher content of β-sheet structures and better mechanical properties.
Our study revealed the structures and mechanical properties of trimolter silk, and provided a valuable reference to improve silk quality by influencing molting in silkworms.
桑蚕丝纤维直径较细，具有轻盈、抗皱的优点。许多研究利用抗保幼激素诱导三眠蚕以产生细丝，但对三眠蚕丝的形态、结构和力学性能的分析相对较少。
本研究通过局部应用抗保幼激素诱导两种三眠蚕，获得了细直径丝。扫描电子显微镜（SEM）、傅里叶变换红外分析（FTIR）、拉伸力学测试、几丁质染色用于揭示三眠蚕丝的形态、构象和力学性能。
三眠蚕的茧由更细的纤维高度密集排列而成，因此孔径较小。我们发现三眠蚕丝丝素的构象发生了变化，形成了更多的β-折叠结构。此外，力学参数分析表明，三眠蚕丝的杨氏模量和强度均高于对照。通过丝腺几丁质染色，我们推测丝腺结构的变化使三眠蚕丝的力学性能得到了极大的增强。
我们通过抗保幼激素诱导三眠蚕，得到的茧更加紧密，丝纤维直径更小。我们发现三眠蚕丝丝素的构象具有更高含量的β-折叠结构和更好的力学性能。
本研究揭示了三眠蚕丝的结构和力学性能，为通过影响蚕的蜕皮来提高蚕丝质量提供了有价值的参考。
