POLYOL ACCUMULATION IN IN VITRO SYSTEMS OF BOMBYX EGGS

Area of Science:

• Biochemistry
• Insect Physiology
• Developmental Biology

Background:

• Diapause is a state of suspended development in insects, crucial for surviving adverse conditions.
• Polyols, such as sorbitol and glycerol, are known cryoprotectants in various organisms.
• Understanding polyol metabolism in diapausing insects is key to insect survival strategies.

Purpose of the Study:

• To investigate the biochemical mechanisms of polyol accumulation in diapausing Bombyx eggs.
• To determine the conversion pathways of glucose-6-phosphate into polyols and neutral sugars in vitro.
• To compare polyol synthesis rates between diapausing and developing Bombyx eggs.

Main Methods:

• In vitro incubation of Bombyx egg homogenates and press juices with [6-14C]glucose-6-phosphate.
• Analysis of labelled products, including trehalose, sorbitol, and glycerol, using radiolabeling techniques.
• Quantitative assessment of 14C-sorbitol formation in different developmental stages and diapause states.

Main Results:

• Incubation with [6-14C]glucose-6-phosphate resulted in the accumulation of labelled trehalose, sorbitol, and glycerol.
• Developing Bombyx eggs showed initial 14C-sorbitol presence, which rapidly decreased during embryonic development.
• Diapausing Bombyx eggs exhibited 3-5 times greater 14C-sorbitol formation compared to developing eggs, especially in early diapause stages.

Conclusions:

• Bombyx eggs actively synthesize polyols from glucose-6-phosphate, with significant accumulation during diapause.
• The rate of sorbitol synthesis is markedly higher in diapausing eggs, suggesting a role in cryoprotection.
• These findings elucidate key metabolic adaptations in Bombyx eggs for overwintering survival.