Photochemical effect of silver nanoparticles on flesh fly larval biological system.

With the progress of nanoscience and its applications, silver nanoparticles (AgNPs) have become one of the most interesting nanoparticles owing to their use in different fields. However, the excessive use of AgNPs and its products may cause toxicity in both the environment and in human health. The main goal of this research is to study the toxic and photochemical effects of AgNPs against Sarcophaga argyrostoma larvae through ultrastructure, morphological change, and DNA damage. Treating midgut epithelium with AgNPs led to many alterations in dark conditions, disintegrated epithelium, swollen cells, and shrunken nucleus. Organelles appeared in a loose manner and mitochondria were without cristae, endoplasmic reticulum had dark spots, and peritrophic membrane was loose in appearance. Fatty tissues were vacuolized and muscle fibers lacked normal striations and had many gaps and lysosomal bodies. In the light conditions, the epithelium appeared with detached cells and many vacuoles, organelles were ruptured with many gaps in between, and secretory vesicles were scattered. Peritrophic membrane disappeared. Muscles collapsed and vacuolized loosed fatty tissues were detected. On the other hand, control larvae epithelium appeared regularly distinct, with organelles intact and muscles had clear normal striations. Data showed that AgNPs caused ultrastructural and morphological changes of the external cuticle of the 4th instar larvae along with a significant effect on DNA damage that occurred after the larval treatment, reflecting the toxicity of AgNPs.

Enzyme activity modification in adult beetles (Agelastica coerulea) inhabiting birch trees in an ozone-enriched atmosphere.

Tropospheric ozone (O3) is a naturally occurring gas in the atmosphere. However, the concentration of O3 increased in the twentieth century. Although the effects of O3 on vegetation have been extensively studied since the 1950s, limited information exists regarding the effects of O3 on insect herbivores. In particular, evidence is lacking regarding the effects of O3 on the biology of insect herbivores. Agelastica coerulea Baly (1874) is a coleopteran species that grazes on Betulaceae plants. In this study, to investigate the effects of O3 on A. coerulea biology for the first time, female adult insects were collected from Japanese white birch trees grown in a Free Air Controlled Exposure System (FACE) in Sapporo, Japan. These beetles inhabited trees exposed either to ambient or to elevated O3 for 23 days. After collection, the enzyme activities in the beetles were measured. Elevated O3 led to a greater total antioxidant activity and lower α- and ß-esterase activities, a phenomenon that may suggest an increased resistance of the beetles to stress. Our results are further discussed with regard to biological and toxicological aspects. Collectively, our findings indicate that total antioxidants and α- and ß-esterase activities can serve as effective O3 biomarker systems in this beetle species. This adaptive response of the beetle, which was induced by moderate O3 exposure, should be further tested across generations and for its protection against greater exposure.