Life History Traits in Two Drosophila Species Differently Affected by Microbiota Diversity under Lead Exposure

A new insight into Cd exposure-induced hemocyte reduction in Lymantria dispar larvae: Involvement of the ROS-ATF6-ER stress-apoptosis pathway

Hemocytes are important targets for heavy metal-induced immunotoxicity in insects. This study aimed to investigate the mechanism by which cadmium (Cd) exposure affects the hemocyte count in Lymantria dispar larvae. The results showed that the number of larval hemocytes was significantly decreased under Cd exposure, accompanied by a significant increase in the apoptosis rate and the expression of Caspase-3. The endoplasmic reticulum (ER) of hemocytes in the Cd-treated group showed irregular swelling. Expression levels of ER stress indicator genes (CHOP, Bip1, Bip2, Bip3, and Bip4) were significantly higher in the Cd-treated group. Among the three pathways that potentially mediate ER stress, only the key genes in the ATF6 pathway (ATF6, S1P-1, S1P-2, and WFS1) exhibited differential responses to Cd exposure. Cd exposure significantly increased the levels of reactive oxygen species (ROS) and the expression of oxidative stress-related genes (CNCC, P38, and ATF2) in hemocytes. Studies using inhibitors confirmed that apoptosis mediated the decrease in hemocyte count, ER stress mediated apoptosis, ATF6 pathway mediated ER stress, and ROS or oxidative stress mediated ER stress through the activation of the ATF6 pathway. Taken together, the ROS-ATF6-ER stress-apoptosis pathway is responsible for the reduction in the hemocyte count of Cd-treated L. dispar larvae.

Klebsiella pneumoniae in the intestines of Musca domestica larvae can assist the host in antagonizing the poisoning of the heavy metal copper

BACKGROUND

Musca domestica larvae are common saprophytes in nature, promoting the material-energy cycle in the environment. However, heavy metal pollution in the environment negatively affects their function in material circulation. Our previous research found that some intestinal bacteria play an important role in the development of housefly, but the responses of microbial community to heavy metal stresses in Musca domestica is less studied.

RESULTS

In this study, CuSO4, CuSO4-Klebsiella pneumoniae mixture and CuSO4-K. pneumoniae phage mixture were added to the larval diet to analyze whether K. pneumoniae can protect housefly larvae against Cu2+ injury. Our results showed that larval development was inhibited when were fed with CuSO4, the bacterial abundance of Providencia in the intestine of larvae increased. However, the inhibition effects of CuSO4 was relieved when K. pneumoniae mixed and added in larval diets, the abundance of Providencia decreased. Electron microscope results revealed that K. pneumoniae showed an obvious adsorption effect on copper ion in vitro.

CONCLUSIONS

Based on the results we assume that K. pneumoniae could adsorb Cu2+, reduce Cu2+ impact on gut community structure. Our study explains the role of K. pneumoniae antagonizing Cu2+, which could be applied as a probiotic to saprophytic bioantagonistic metal contamination.

Special Issue: Selected Papers from the 1st International Electronic Conference on Entomology

The 1st International Electronic Conference on Entomology (1IECE) was held between 1 and 15 July 2021 on the MDPI Sciforum platform organized and funded by the international journal Insects [...].