Homeostatic Regulation of the Duox-ROS Defense System: Revelations Based on the Diversity of Gut Bacteria in Silkworms (Bombyx mori)

Abstract

The Duox-ROS defense system plays an important role in insect intestinal immunity. To investigate the role of intestinal microbiota in Duox-ROS regulation herein, 16S rRNA sequencing technology was utilized to compare the characteristics of bacterial populations in the midgut of silkworm after different time-periods of treatment with three feeding methods: 1–4 instars artificial diet (AD), 1–4 instars mulberry leaf (ML) and 1–3 instars artificial diet + 4 instar mulberry leaf (TM). The results revealed simple intestinal microbiota in the AD group whilst microbiota were abundant and variable in the ML and TM silkworms. By analyzing the relationship among intestinal pH, reactive oxygen species (ROS) content and microorganism composition, it was identified that an acidic intestinal environment inhibited the growth of intestinal microbiota of silkworms, observed concurrently with low ROS content and a high activity of antioxidant enzymes (SOD, TPX, CAT). Gene expression associated with the Duox-ROS defense system was detected using RT-qPCR and identified to be low in the AD group and significantly higher in the TM group of silkworms. This study provides a new reference for the future improvement of the artificial diet feeding of silkworm and a systematic indicator for the further study of the relationship between changes in the intestinal environment and intestinal microbiota balance caused by dietary alterations.

Changes in the bacterial communities of Harmonia axyridis (Coleoptera: Coccinellidae) in response to long-term cold storage and progressive loss of egg viability in cold-stored beetles

“…For example, low temperature can induce an increased production of antioxidant enzymes in H. axyridis adults ( Awad et al, 2021 ). However, it should be noted that a high activity of antioxidant enzymes may create an unfavorable environment for the growth of some specific bacteria, such as the intestinal microbiota in Bombyx mori L. ( Shu et al, 2023 ). Functionally, these three aforementioned bacterial phyla have been demonstrated to play crucial roles in energy metabolism and nutrient absorption, thereby contributing to the successful growth and reproduction of their hosts ( Schrempf, 2001 ; Reid et al, 2011 ; Flint et al, 2012 ; Colston and Jackson, 2016 ).…”