Impact of honey-enriched mulberry diet on the energy metabolism of the silkworm, Bombyx mori

Abstract

The present study was taken-up with a view to clearly define the role of oxidative phosphorylation vis-a-vis transdeamination in Bombyx mori metamorphosis, under the influence of honey-enriched mulberry diet. Therefore, the study examined the accumulation and utilization patterns of carbohydrate (glycogen, trehalose, glucose) and non-carbohydrate energy reserves (proteins, amino acids) in its fat body during larval, pupal and adult stages. In accordance with Hutchinson’s investment principle, the energy reserves invested during larval stage are partly used in pupal stage and those invested during larval and pupal stages are used in adult stage. Their utilization patterns are correlated with the activity levels of succinate (SDH) and glutamate (GDH) dehydrogenases and aspartate (AAT) and alanine (ALAT) aminotransferases and changes thereof were interpreted in terms of glycolytic oxidative phosphorylation and non-glycolytic transdeamination.  The trends in mass incorporation rates vis-à-vis enzyme activities indicated that the metabolism-related energy needs of all metamorphic events are majorly met through a gluconeogenetic mechanism called transdeamination, while the behavioural-related energy demands of larval and pupal stages are fulfilled through glycolytic-based oxidative phosphorylation. The activity trends further indicated that AAT plays major role in meeting the energy needs of larva and pupa, while GDH predominantly meets the energy requirements of reproduction in adults. The honey-enriched mulberry diet showed stage-specific and pathway-specific impacts on energy metabolism. It positively reinforced the energy metabolism in larval stage, but showed no significant effect in pupal and adult stages. Similarly, it showed more promising effect on glycolytic-oxidative phosphorylation and null or neutral effect on transdeamination.