Didugu Brinda Goda Lakshmi, Mamillapalli Anitha
Department of Life Sciences, GITAM School of Science, GITAM (Deemed to Be University), Visakhapatnam, Andhra Pradesh, 530 045, India.
Amino Acids. 2025 Jun 13;57(1):33. doi: 10.1007/s00726-025-03462-5.
Silk glands are modified labial glands that produce silk which has immense commercial importance. Silk is extruded out in liquid form after which the glands undergo autophagy and apoptosis during larval to pupal transition. Biogenic amines, specially spermidine and γ-aminobutyric acid (GABA) are known to play an important role in autophagy. Yet, GABA is not identified in the silk glands till now and therefore its role in autophagy remains unknown. Current study aimed to evaluate role of biogenic amines in the autophagy of silk glands. Fifth instar silkworms were fed with control and spermidine supplemented mulberry leaves under controlled conditions. Qualitative and quantitative analysis of biogenic amines were analyzed in silk glands of control and spermidine fed groups at the end of feeding stage, spinning and pre-pupal stages. Biogenic amines were significantly decreased in the silk glands from feeding stage to non-feeding prepupal stages. Elevated levels of biogenic amines; putrescine, spermidine, and spermine were observed in silk glands at pre-pupal stage in the spermidine fed group. The unknown biogenic amine whose levels were significantly elevated during silk gland degeneration in both control and spermidine fed groups was identified as GABA by spectroscopic techniques. This is the first report of the identification of GABA in the silk glands of Bombyx mori which increased significantly following spermidine supplementation, resulting in elevated levels of calcium deposits, contributing to the early degeneration of the silk glands.
丝腺是经过改造的唇腺，能产生具有巨大商业价值的丝。丝以液体形式挤出，之后在幼虫向蛹转变的过程中，丝腺会经历自噬和凋亡。已知生物胺，特别是亚精胺和γ-氨基丁酸（GABA）在自噬中起重要作用。然而，到目前为止在丝腺中尚未鉴定出GABA，因此其在自噬中的作用仍然未知。当前的研究旨在评估生物胺在丝腺自噬中的作用。在可控条件下，给五龄蚕喂食对照桑叶和添加了亚精胺的桑叶。在喂食阶段结束、吐丝阶段和预蛹阶段，对对照和喂食亚精胺组的丝腺中的生物胺进行定性和定量分析。从喂食阶段到不进食的预蛹阶段，丝腺中的生物胺显著减少。在喂食亚精胺组的预蛹阶段，丝腺中腐胺、亚精胺和精胺等生物胺水平升高。通过光谱技术鉴定出在对照和喂食亚精胺组的丝腺退化过程中水平显著升高的未知生物胺为GABA。这是在家蚕丝腺中鉴定出GABA的首次报道，补充亚精胺后GABA显著增加，导致钙沉积水平升高，促成丝腺的早期退化。
