H_(2)S promotes developmental brain angiogenesis via the NOS/NO pathway in zebrafish

Background Hydrogen sulphide(H_(2)S)is considered as the third member of the gasotransmitter family,along with nitric oxide(NO)and carbon monoxide.H_(2)S has been reported to induce angiogenesis by promoting the growth,migration and tube-like structure formation of endothelial cells.Those studies were conducted in conditions of cell culture,mouse Matrigel plug assay model,rat wound healing model or rat hindlimb ischaemia model.Recent in vivo studies showed the physiological importance of H_(2)S in muscle angiogenesis.However,the importance of endogenous H_(2)S for brain angiogenesis during development remains unknown.We therefore aimed at determining the role of H_(2)S in brain vascular development.Methods and results Both knockdown and knockout of H2S-producing enzymes,cystathionineβ-synthase(cbs)and cystathionineγ-lyase(cth),using morpholino oligonucleotides and clustered regularly interspaced short palindromic repeats/Cas9-mediated mutation,impaired brain vascular development of larval zebrafish.Incubation with the slow-releasing H_(2)S donor GYY4137 alleviated the defects of brain vascular development in cbs and cth morphants.Quantitative analysis of the midbrain vascular network showed that H_(2)S enhances angiogenesis without affecting the topological structure of the brain vasculature.Mechanically,nitric oxide synthase 2a(nos2a)expression and NO production were decreased in both cbs and cth morphants.Overexpression of nos2a by coinjection of cbs or cth MO with full-length zebrafish nos2a mRNA alleviated the brain vascular developmental defects in cbs and cth morphants.Conclusion We conclude that H_(2)S promotes brain developmental angiogenesis via the NOS/NO pathway in zebrafish.

Retinal bipolar cells——A model for the study of neuronal signal integration

Being the functional basis of neural networks, neuronal signal integration has been currently becoming a hot point of neuroscience research. Active and passive membrane properties of retinal bipolar cells, temporal and spatial distribution of synaptic inputs to these cells are described, and modulation of signal integration characteristics of these cells under different reti-

Optic tecta I superficial inter neurons detect motion in larval zebrafish

Detection of moving objects is an essential skill for animals to hunt prey,recognize conspecifics and avoid predators.The zebrafish,as a vertebrate model,primarily uses its elaborate visual system to distinguish moving objects against background scenes.The optic tectum(OT)receives and integrates inputs from various types of retinal ganglion cells(RGCs),including direction-selective(DS)RGCs and size-selective RGCs,and is required for both prey capture and predator avoidance.However,it remains largely unknown how motion information is processed within the OT.Here we performed in vivo whole-cell recording and calcium imaging to investigate the role of superficial interneurons(SINs),a specific type of optic tecta I neurons,in motion detection of larval zebrafish.SINs mainly receive excitatory synaptic inputs,exhibit transient ON-or OFF-type of responses evoked by light flashes,and possess a large receptive field(RF).One fifth of SINs are DS and classified into two subsets with separate preferred directions.Furthermore,SINs show size-dependent responses to moving dots.They are efficiently activated by moving objects but not static ones,capable of showing sustained responses to moving objects and having less visual adaptation than periventricular neurons(PVNs),the principal tecta I cells.Behaviorally,ablation of SINs impairs prey capture,which requires local motion detection,but not global looming-evoked escape.Finally,starvation enhances the gain of SINs'motion responses while maintaining their size tuning and DS.These results indicate that SINs serve as a motion detector for sensing and localizing sized moving objects in the visual field.

Theoretical self-consistency in nonextensive statistical mechanics with parameter transformation

Self-consistency in nonextensive statistical mechanics is studied as a recourse to parameter transformation,where different nonextensive parameters are presented for various theoretical branches.The unification between the first and third choices of the average definition and that between the normal and escort distributions are both examined.The problem of parameter inversion in the generalized H theorem is also investigated.The inconsistency between the statistical ensemble pressure and molecular dynamics pressure can be eliminated.This work also verifies the equivalence of physical temperature and gravitational temperature in nonextensive statistical mechanics.In these parameter transformations,the Tsallis entropy form is observed to remain invariant.

The collision frequency of electron-neutralparticle in weakly ionized plasmas with non-Maxwellian velocity distributions

The collision frequencies of electron-neutral-particle in weakly ionized complex plasmas with the non-Maxwellian velocity distributions are studied.The average collision frequencies of electron-neutral-particle in plasmas are accurately derived.We find that these collision frequencies are significantly dependent on the power-law spectral indices of non-Maxwellian distribution functions and so they are generally different from the collision frequencies in plasmas with a Maxwellian velocity distribution,which will affect the transport properties of the charged particles in plasmas.Numerically analyses are made to show the roles of the spectral indices in the average collision frequencies respectively.

Efficient replacement of long DNA fragments via non-homologous end joining at norrcoding regions

Targeted double-strand breaks(DSBs)in genomes can be introduced efficiently by endonucleases(Umov et al.,2010;Jinek et al.,2012;Joung and Sander,2013),including zinc-finger nucleases,tran scription activator-like effector nu cleases,and clustered regularly in terspaced palindromic repeats(CRISPR)/Cas9.After DSBs,DNA repair is mainly via homology-directed repair(HDR)and/or non-homologous end joining(NHEJ)(Hustedt and Durocher,2016).It was reported that genomic DNA replacement can be achieved via HDR at the site of DSBs in multiple organisms(Dickinson et al.,2013;Yang et al.,2013;Zu et al.,2013),but the efficiency is still not enough for general application,in particular for replacing long DNA fragment that is more than hundreds of base pairs(bps).As NHEJ is 10-fold more active than HDR at DSB sites(Mao et al.,2008),we speculated that NHEJ can be utilized to implement long genomic DNA replacement with high efficiency.