Protein-based materials are considered versatile biomaterials, and their biodegradability is an advantage for sustainable development. Bagworm produces strong silk for use in unique situations throughout its life stages. Rigorous molecular analyses of Eumeta variegata suggested that the particular mechanical properties of its silk are due to the coexistence of poly-A and GA motifs. However, little molecular information on closely related species is available, and it is not understood how these properties were acquired evolutionarily or whether the motif combination is a conserved trait in other bagworms. Here, we performed a transcriptome analysis of two other bagworm species (Canephora pungelerii and Bambalina sp.) belonging to the family Psychidae to elucidate the relationship between the fibroin gene and silk properties. The obtained transcriptome assemblies and tensile tests indicated that the motif combination and silk properties were conserved among the bagworms. Furthermore, our analysis showed that C. pungelerii produces extraordinarily strong silk (breaking strength of 1.4 GPa) and indicated that the cause may be the C. pungelerii -specific balance of crystalline/amorphous regions in the H-fibroin repetitive domain. This particular H-fibroin architecture may have been evolutionarily acquired to produce strong thread to maintain bag stability during the relatively long development period of Canephora species relative to other bagworms.

中文翻译：

---

丝心蛋白结构中结晶和无定形区域的平衡支撑着蚕丝的拉伸强度

蛋白质基材料被认为是多功能生物材料，其生物降解性是可持续发展的优势。袋虫生产结实的丝，用于其整个生命阶段的独特情况。对 Eumeta variegata 的严格分子分析表明，其丝的特殊机械性能是由于 poly-A 和 GA 基序的共存。然而，关于密切相关物种的分子信息很少，并且不了解这些特性是如何通过进化获得的，或者基序组合是否是其他袋虫的保守性状。在这里，我们对属于 Psychidae 科的另外两种袋虫（Canephora pungelerii 和 Bambalina sp.）进行了转录组分析，以阐明丝心蛋白基因与蚕丝特性之间的关系。获得的转录组组装和拉伸测试表明，袋虫中的基序组合和丝特性是保守的。此外，我们的分析表明，C. pungelerii 产生非常强的丝（断裂强度为 1.4 GPa），并表明原因可能是 C. pungelerii 特定的 H-丝心蛋白重复结构域中结晶/无定形区域的平衡。这种特殊的 H-丝心蛋白结构可能是进化获得的，以产生强线，以在 Canephora 物种相对于其他袋虫相对较长的发育期间保持袋子的稳定性。pungelerii 产生异常坚固的丝（断裂强度为 1.4 GPa），并表明原因可能是 C. pungelerii 特定的 H-丝心蛋白重复结构域中结晶/无定形区域的平衡。这种特殊的 H-丝心蛋白结构可能是进化获得的，以产生强线，以在 Canephora 物种相对于其他袋虫相对较长的发育期间保持袋子的稳定性。pungelerii 产生异常坚固的丝（断裂强度为 1.4 GPa），并表明原因可能是 C. pungelerii 特定的 H-丝心蛋白重复结构域中结晶/无定形区域的平衡。这种特殊的 H-丝心蛋白结构可能是进化获得的，以产生强线，以在 Canephora 物种相对于其他袋虫相对较长的发育期间保持袋子的稳定性。