Generation and manipulation of bright spatial bound-soliton pairs under the diffusion effect in photovoltaic photorefractive crystals

The generation and propagation characteristics of bright spatial bound-soliton pairs (BSPs) are investigated under the diffusion effect in photovoltaic photorefractive crystals by numerical simulation. The results show that two coherent solitons, one as the signal light and the other as the control light, can form a BSP when the peak intensity of the control light is appropriately selected. Moreover, under the diffusion effect, the BSP experiences a self-bending process during propagating and the center of the BSP moves on a parabolic trajectory. Furthermore, the lateral shift of the BSP at the output face of the crystal can be manipulated by adjusting the peak intensity of the control light. The research results provide a method for the design of all-optical switching and routing based on the manipulation of the lateral position of BSPs.

The chemical reprogramming of unipotent adult germ cells towards authentic pluripotency and de novo establishment of imprinting

Although somatic cells can be reprogrammed to pluripotent stem cells(PsCs)with pure chemicals,authentic pluripotency of chemically induced pluripotent stem celis(CipsCs)has never been achieved through tetraploid complementation assay.Spontaneous reprogramming of spermatogonial stem cells(ssCs)was another non-transgenic way to obtain PsCs,but this process lacks mechanistic explanation.Here,we reconstructed the trajectory of mouse SsC reprogramming and developed a five-chemical combination,boosting the reprogramming effciency by nearly 80-to 100-folds.More importantly,chemical induced germline-derived PsCs(5C-gPSCs),but not gpsCs and chemical induced pluripotent stem cells,had authentic pluripotency,as determined by tetraploid complementation.Mechanistically,ssCs traversed through an inverted pathway of in vivo germ ceil development,exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts.Besides,ssC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5c-gPsCs,which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles.Our work sheds ight on the unique regulatory network underpinning SsC reprogramming,providing insights to understand generic mechanisms for cell-fate decision and epigenetic-relateddisorders in regenerative medicine.

LES investigation of the tip vortex cavitating flow with special emphasis on the interaction between cavitation and vorticity by a modified cavitation model

Cavitation within the tip vortex(TV)flow remains a challenging issue in the design of high-speed and low-noise hydraulic machinery.In this paper,the TV cavitating flow around an elliptical hydrofoil is calculated by using large eddy simulation(LES)combined with a modified Schnerr-Sauer(S-S)cavitation model.The original S-S cavitation model is modified by taking into account the typical effect of vortex flow.The partial pressure term which can describe the vortex quantitatively and qualitatively is confirmed asρ_(m)ω^(2) x r _(c)^(2) ,and is considered into the R-P equation of the modified S-S cavitation model.Comparison between the numerical and experimental results shows good agreement in the form and evolution of cavities,including attached cavities(AC)and tip vortex cavities(TVC).The vorticity transport equation is utilized to investigate the dynamic mechanisms of the vortex development around the TVC.Further analyses indicate that cavitation in the TV flow influences the pressure in the core of the cavity and the local flow patterns.Typical vortex structures in the TV cavitating flow include TV,secondary vortex(SV)and wake vortex(WV).The direction and magnitude of the rotation effect can be described by axial vorticity which is drawn on the iso-surface of Q=1×105 s−2.The development of the TV cavitating flow can be divided into two stages:Stage I,the development and fusion of TV,SV,stage II,the dissipation of SV.The stretching term dominates the evolution of TV,and the dilatation term is the main reason in the mergence process of SV.

Rapid conversion of human ESCs into mouse ESC-like pluripotent state by optimizing culture conditions

The pluripotent state between human and mouse embryonic stem cells is different.Pluripotent state of human embryonic stem cells(ESCs)is believed to be primed and is similar with that of mouse epiblast stem cells(EpiSCs),which is different from the naïve state of mouse ESCs.Human ESCs could be converted into a naïve state through exogenous expression of defined transcription factors(Hanna et al.,2010).Here we report a rapid conversion of human ESCs to mouse ESC-like naïve states only by modifying the culture conditions.These converted human ESCs,which we called mhESCs(mouse ESC-like human ESCs),have normal karyotype,allow single cell passage,exhibit domed morphology like mouse ESCs and express some pluripotent markers similar with mouse ESCs.Thus the rapid conversion established a naïve pluripotency in human ESCs like mouse ESCs,and provided a new model to study the regulation of pluripotency.

Generation of tetraploid complementation mice from embryonic stem cells cultured with chemical defined medium

Mouse embryonic stem cells(mESCs)derived from inner cell mass(ICM)of pre-implantation embryos,can maintain undifferentiated state when cultured in N2B27 medium supplemented with GSK3inhibitor CHIR99021 and MEK inhibitor PD0325901(‘‘2i’’)and leukemia inhibitor factor(LIF).Compare to conventional culture medium,all components of this medium are defined.With the N2B27 medium,‘‘2i’’and LIF,mESCs can contribute to the germline of the chimeric embryos,however,whether the‘‘all-ES cells’’mice can been generated by tetraploid complementation is unclear yet,while the tetraploid complementation serve as a golden standard to assess the pluripotency of ES cells.Here,our study showed that mESCs derived and cultured with the N2B27 complete medium could generate fertile mice by tetraploid complementation.In addition,the survival rate of tetraploid complementation mice produced by inbred mES cell lines is higher than the conventional culture condition,and increased the percentage of Oct4 positive cells contrast to conventional medium either.Therefore,the N2B27 medium supplemented with‘‘2i’’and LIF is an alternative choice forthe derivation and long-term culture of mouse embryonic stem cells.

Derivation of Non-Integration Induced Pluripotent Stem Cells from Fibroblast of Severe Deafness Patients with GJB2 Mutation

In all the connexin-associated human diseases, deafness is one of the most important diseases with high frequency. The mu- tations of GJB2 （gap junction protein β2, also called connexin 26, Cx26） gene link with nonsyndromic or syndromic senso- rineural hearing loss and were shown to account for a large proportion of congenital deaf cases in many studied populations （del Castillo and del Castillo, 2011）. For example, the 235de1C mutation in GJB2 shows the frequency of approximately 1% and is the most frequent mutation in East Asian population （Yan et al., 2003）. Many efforts have been put to study the function of Gjb2 gene in both mouse model and human. In mouse, extensive deletion of Gjb2 causes embryo lethal due to the decreased transplacental glucose uptake, which was not found in human （Takata and Hirano, 1997; Gabriel et al., 1998）. In human, GJB2 deficiency is not able to cause embryo lethal （D＇Andrea et al., 2002）. However, the study of GJB2-associated hearing loss is hampered by many difficulties, such as unobtainable human cochlea and acoustic nerve tissues, and therefore the GJB2-associated hearing loss are underlying mechanisms of still remaining unclear.

Pluripotency of Induced Pluripotent Stem Cells

Induced pluripotent stem （iPS） cells can be generated by forced expression of four pluripotency factors in somatic cells. This has received much attention in recent years since it may offer us a promising donor cell source for cell transplantation therapy. There has been great progress in iPS cell research in the past few years. However, several issues need to be further addressed in the near future before the clinical application of iPS cells, like the immunogenieity of iPS cells, the variability of differentiation potential and most importantly tumor formation of the iPS derivative cells. Here, we review recent progress in research into the pluripotency of iPS cells.

Durable pluripotency and haploidy in epiblast stem cells derived from haploid embryonic stem cells in vitro

Haploid pluripotent stem cells,such as haploid embryonic stem cells(haESCs),facilitate the genetic study of recessive traits.In vitro,fish haESCs maintain haploidy in both undifferentiated and differentiated states,but whether mammalian haESCs can preserve pluripotency in the haploid state has not been tested.Here,wereport thatmousehaESCs can differentiate in vitro into haploid epiblast stem cells(haEpiSCs),which maintain an intact haploid genome,unlimited self-renewal potential,and durable pluripotency to differentiate into various tissues in vitro and in vivo.Mechanistically,the maintenance of self-renewal potential depends on the Activin/bFGF pathway.We further show that haEpiSCs can differentiate in vitro into haploid progenitor-like cells.When injected into the cytoplasm of an oocyte,androgenetic haEpiSC(ahaEpiSCs)can support embryonic development until midgestation(E12.5).Together,these resultsdemonstrate durable pluripotency inmousehaESCs andhaEpiSCs,aswell asthe valuable potential of using these haploid pluripotent stem cells in high-throughput genetic screening.

RNA Guided Genome Editing in Mouse Germ-Line Stem Cells

Spermatogonial stem cells （SSCs） reside on the basement membrane of the seminiferous tubules in mammalian testes （Nagano et al., 1998）. After isolation and purification of SSCs from mouse testis, SSCs can be cultured in vitro to derive germ-line stem cells （GSCs） which have the ability of proliferation over 2 years （Kanatsu-Shinohara et al.. 2003;