The negative effect of the PI3K inhibitor 3-methyladenine on planarian regeneration via the autophagy signalling pathway

Neurotoxicological mechanisms of carbon quantum dots in a new animal model Dugesia japonica

As luminescent nanomaterials, the carbon quantum dots (CQDs) research focused on emerging applications since their discovery. However, their toxicological effects on the natural environment are still unclear. The freshwater planarian Dugesia japonica is distributed extensively in aquatic ecosystems and can regenerate a new brain in 5 days after amputation. Therefore it can be used as a new model organism in the field of neuroregeneration toxicology. In our study, D. japonica was cut and incubated in medium treated with CQDs. The results showed that the injured planarian lost the neuronal ability of brain regeneration after treatment with CQDs. Its Hh signalling system was interfered with at Day 5, and all cultured pieces died on or before Day 10 due to head lysis. Our work reveals that CQDs might affect the nerve regeneration of freshwater planarians via the Hh signalling pathway. The results of this study improve our understanding of CQD neuronal development toxicology and can aid in the development of warning systems for aquatic ecosystem damage.

Using autophagy, apoptosis, cytoskeleton, and epigenetics markers to investigate the origin of infertility in ex-fissiparous freshwater planarian individuals (nomen nudum species) with hyperplasic ovaries

The origin of the sterility observed in ex-fissiparous freshwater planarians with hyperplasic ovaries has yet to be explained. To improve our understanding of this enigmatic phenomenon, immunofluorescence staining and confocal microscopy examination were used the assess autophagy, apoptosis, cytoskeleton, and epigenetics markers in the hyperplasic ovaries of ex-fissiparous individuals and the normal ovaries of sexual individuals. Immunofluorescence positivity for the autophagic marker microtubule-associated protein1 light chain 3 (LC3) was significantly lower in the hyperplasic ovary than in the normal ovary. Compared with the normal ovary, the hyperplasic ovary exhibited significantly higher immunofluorescence positivity for the apoptotic marker caspase 3, suggesting that autophagy and apoptosis are closely associated in this pathogenicity. Furthermore, the level of global DNA (cytosine-5)-methyltransferase 3A (DNMT3) protein expression was significantly higher in the normal ovary than in the hyperplasic ovary, suggesting that DNA methylation is involved in the infertility phenomenon. The cytoskeleton marker actin also exhibited relatively higher immunofluorescence intensity in the normal ovary than in the hyperplasic ovary, consistent with previous findings on the role of cytoskeleton architecture in oocyte maturation. These results help improve our understanding of the causes of infertility in ex-fissiparous planarians with hyperplasic ovaries and provide new insights that will facilitate future studies on this mysterious pathogenicity.