Coexisting fast–slow dendritic traveling waves in a 3D-array electric field coupled neuronal network

Coexistence of fast and slow traveling waves without synaptic transmission has been found in hhhippocampal tissues,which is closely related to both normal brain activity and abnormal neural activity such as epileptic discharge. However, the propagation mechanism behind this coexistence phenomenon remains unclear. In this paper, a three-dimensional electric field coupled hippocampal neural network is established to investigate generation of coexisting spontaneous fast and slow traveling waves. This model captures two types of dendritic traveling waves propagating in both transverse and longitude directions: the N-methyl-D-aspartate(NMDA)-dependent wave with a speed of about 0.1 m/s and the Ca-dependent wave with a speed of about 0.009 m/s. These traveling waves are synaptic-independent and could be conducted only by the electric fields generated by neighboring neurons, which are basically consistent with the in vitro data measured experiments. It is also found that the slow Ca wave could trigger generation of fast NMDA waves in the propagation path of slow waves whereas fast NMDA waves cannot affect the propagation of slow Ca waves. These results suggest that dendritic Ca waves could acted as the source of the coexistence fast and slow waves. Furthermore, we also confirm the impact of cellular spacing heterogeneity on the onset of coexisting fast and slow waves. The local region with decreasing distances among neighbor neurons is more liable to promote the onset of spontaneous slow waves which, as sources, excite propagation of fast waves. These modeling studies provide possible biophysical mechanisms underlying the neural dynamics of spontaneous traveling waves in brain tissues.

A new chloro-azaphilone derivative with pro-angiogenesis activity from the hadal trench-derived fungus Chaetomium globosum YP-106

A new chloro-azaphilone derivative chaetoviridin L(1)along with four known analogues,namely,chaetomugilin A(2),chaetoviridin E(3),chaetomugilin O(4),and chaephilone D(5),is isolated and identified from the culture extract of Chaetomium globosum YP-106,a deep-sea derived fungus obtained from the hadal zone seawater collected in the Yap Trench.Their structures were determined based on detailed interpretation of nuclear magnetic resonance(NMR)spectroscopic,mass spectrometry(MS)data analysis and comparison with the reported literature.The absolute configuration of the new compound was established by quantum chemical calculations of electronic circular dichroism(ECD).All the isolated compounds were evaluated for pro-angiogenesis activity using zebra fish model.Compounds 1,2,and 5significantly promoted the angiogenesis in a dose-dependent manner and thus,these compounds might be used as promising molecules for the treatment of cardiovascular disease.