The latent dedifferentiation capacity of newt limb muscles is unleashed by a combination of metamorphosis and body growth.

Newts can regenerate their limbs throughout their life-span. Focusing on muscle, certain species of newts such as Cynops pyrrhogaster dedifferentiate muscle fibers in the limb stump and mobilize them for muscle creation in the regenerating limb, as they grow beyond metamorphosis. However, which developmental process is essential for muscle dedifferentiation, metamorphosis or body growth, is unknown. To address this issue, we tracked muscle fibers during limb regeneration under conditions in which metamorphosis and body growth were experimentally shifted along the axis of development. Our results indicate that a combination of metamorphosis and body growth is necessary for muscle dedifferentiation. On the other hand, ex vivo tracking of larval muscle fibers revealed that newt muscle fibers have the ability to dedifferentiate independently of metamorphosis and body growth. These results suggest that newt muscle fibers have an intrinsic ability to dedifferentiate, but that metamorphosis and body growth are necessary for them to exhibit this hidden ability. Presumably, changes in the extracellular environment (niche) during developmental processes allow muscle fibers to contribute to limb regeneration through dedifferentiation. This study can stimulate research on niches as well as gene regulation for dedifferentiation, contributing to a further understanding of regeneration and future medical applications.

[Isolation and identification of Suavissimoside R1 from roots of Rubus parvifollus used for protecting dopaminergic neurons against MPP+ toxicity].

OBJECTIVE: Suavissimoside R1 was isolated and identified as an active ingredient from Roots of Rubus parvifollus L, which exhibited protective effect on dopaminergic neurons against MPP+ toxicity. METHODS: The protective effects of crude extracts were investigated after mice were treated with 1-methyl4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). According to the protective effects of crude extracts, suavissimoside R1, one kind of triterpenoid saponin, was separated. It was investigated that whether Suavissimoside R1 can protect DA neurons from toxicity induced by MPP+ in rat mesencephalic cultures. RESULTS: Suavissimoside R1 was isolated from Roots of Rubus parvifollus L. Moreover, Suavissimoside R1, in dose of 100 micromol/L, alleviated the death of DA neurons induced by MPP+ obviously. CONCLUSION: These results suggest that suavissimoside R1 possesses potent neuroprotective activity and can be developed to be a potential anti-Parkinson's disease drug worthy for further study.