Bombyx mori (B. mori) is often subjected to
phoxim poisoning in China due to
phoxim exposure, which leads to a decrease in
silk production. Nanoparticulate (NP)
titanium dioxide (nano-TiO2) has been shown to attenuate damages in B. mori caused by
phoxim exposure. However, little is known about the molecular mechanisms of midgut injury due to organophosphorus
insecticide exposure and its repair by
nano-TiO2 pretreatment. In this study,
phoxim exposure for 36 h led to significant decreases in
body weight and survival and increased oxidative stress and midgut injury. Pretreatment with
nano-TiO2 attenuated the
phoxim-induced midgut injury, increased
body weight and survival, and decreased oxidative stress in the midgut of B. mori. Digital gene-expression data showed that exposure to
phoxim results in significant changes in the expression of 254 genes in the
phoxim-exposed midgut and 303 genes in phoxim + nano-TiO2-exposed midgut. Specifically,
phoxim exposure led to upregulation of Tpx, α-
amylase,
trypsin, and
glycoside hydrolase genes involved in digestion and absorption.
Phoxim exposure also led to the downregulation of Cyp450 and Cyp4C1 genes involved in an
antioxidant capacity. In contrast, a combination of both
phoxim and
nano-TiO2 treatment significantly decreased the change in α-
amylase,
trypsin, and
glycoside hydrolases (GHs), which are involved in digestion and absorption. These results indicated that Tpx, α-
amylase,
trypsin, GHs, Cyp450, and Cyp4C1 may be potential
biomarkers of midgut toxicity caused by
phoxim exposure and the attenuation of these toxic impacts by
nano-TiO2.