Dynamic Pax6 expression during the neurogenic cell cycle influences proliferation and cell fate choices of retinal progenitors

BACKGROUND: The paired homeobox protein Pax6 is essential for proliferation and pluripotency of retinal progenitors. However, temporal changes in Pax6 protein expression associated with the generation of various retinal neurons have not been characterized with regard to the cell cycle. Here, we examine the dynamic changes of Pax6 expression among chicken retinal progenitors as they progress through the neurogenic cell cycle, and determine the effects of altered Pax6 levels on retinogenesis. RESULTS: We provide evidence that during the preneurogenic to neurogenic transition, Pax6 protein levels in proliferating progenitor cells are down-regulated. Neurogenic retinal progenitors retain a relatively low level of Pax6 protein, whereas postmitotic neurons either elevate or extinguish Pax6 expression in a cell type-specific manner. Cell imaging and cell cycle analyses show that neurogenic progenitors in the S phase of the cell cycle contain low levels of Pax6 protein, whereas a subset of progenitors exhibits divergent levels of Pax6 protein upon entering the G2 phase of the cell cycle. We also show that M phase cells contain varied levels of Pax6, and some correlate with the onset of early neuronal marker expression, forecasting cell cycle exit and cell fate commitment. Furthermore, either elevating or knocking down Pax6 attenuates cell proliferation and results in increased cell death. Reducing Pax6 decreases retinal ganglion cell genesis and enhances cone photoreceptor and amacrine interneuron production, whereas elevating Pax6 suppresses cone photoreceptor and amacrine cell fates. CONCLUSION: These studies demonstrate for the first time quantitative changes in Pax6 protein expression during the preneurogenic to neurogenic transition and during the neurogenic cell cycle. The results indicate that Pax6 protein levels are stringently controlled in proliferating progenitors. Maintaining a relatively low Pax6 protein level is necessary for S phase re-entry, whereas rapid accumulation or reduction of Pax6 protein during the G2/M phase of the cell cycle may be required for specific neuronal fates. These findings thus provide novel insights on the dynamic regulation of Pax6 protein among neurogenic progenitors and the temporal frame of neuronal fate determination

A Descriptive Model of Robot Team and the Dynamic Evolution of Robot Team Cooperation

At present, the research on robot team cooperation is still in qualitative analysis phase and lacks the description model that can quantitatively describe the dynamical evolution of team cooperative relationships with constantly changeable task demand in Multi-robot field. First this paper whole and static describes organization model HWROM of robot team, then uses Markov course and Bayesian theorem for reference, dynamical describes the team cooperative relationships building. Finally from cooperative entity layer, ability layer and relative layer we research team formation and cooperative mechanism, and discuss how to optimize relative action sets during the evolution. The dynamic evolution model of robot team and cooperative relationships between robot teams proposed and described in this paper can not only generalize the robot team as a whole, but also depict the dynamic evolving process quantitatively. Users can also make the prediction of the cooperative relationship and the action of the robot team encountering new demands based on this model. Journal web page & a lot of robotic related papers www.ars-journal.co

The Metabolism of Baicalin in Rat and the Biological Activities of the Metabolites

Baicalin is one of the major bioactive constituents of Scutellariae Radix, but the biotransformation of it is poorly understood. In this paper, the metabolism of baicalin in rat was studied. Nine metabolites including one new compound were isolated and identified structurally. The plausible scheme for the biotransformation pathways of baicalin in the rats was deduced. And the main metabolites were evaluated for their antioxidation and anti-inflammation biological activities for the first time

Ballistic Thermal Rectification in Asymmetric Three-Terminal Mesoscopic Dielectric Systems

By coupling the asymmetric three-terminal mesoscopic dielectric system with a temperature probe, at low temperature, the ballistic heat flux flow through the other two asymmetric terminals in the nonlinear response regime is studied based on the Landauer formulation of transport theory. The thermal rectification is attained at the quantum regime. It is a purely quantum effect and is determined by the dependence of the ratio $\tau_{RC}(\omega)/\tau_{RL}(\omega)$ on $\omega$, the phonon's frequency. Where $\tau_{RC}(\omega)$ and $\tau_{RL}(\omega)$ are respectively the transmission coefficients from two asymmetric terminals to the temperature probe, which are determined by the inelastic scattering of ballistic phonons in the temperature probe. Our results are confirmed by extensive numerical simulations.Comment: 10 pages, 4 figure

A Study of Lateral Bearing Capacity of Pile by Dynamic Test

In order to improve the knowledge of the Lateral Loading behavior of artificially drilled cast-in-place concrete piles, the full-scale lateral static and dynamic loading tests of eleven piles had been carried out by the authors in Louyang, China. In this paper, the principle of laterally dynamic pile test is discussed. The results of the static and dynamic tests performed in the light of different diameter piles are analyzed comparatively. It is found that the critical loads defined by the dynamic testing are almost identical with results of the static testing ones. Thus we come to a conclusion that the lateral critical loading of the single pile in the area can be determined by dynamic testing method

Making reputation system traceable without losing privacy

U postojećim čvorovima sustava ugleda obično se prihvaćaju redoviti pseudonimi umjesto pravog identiteta radi postizanja anonimnosti. Međutim, potpuna anonimnost će uzrokovati prekretnicu i Sybil napad, koji bi sustav ugleda stavio izvan kontrole i razbio pravičnost sustava ugleda. Ovaj rad predstavlja uvjetni mehanizam anonimnosti za provjeru vrednovanja između anonimnosti čvorova, vrednovanja između dva čvora ako se ne ponavlja nekoliko puta, ne može se vrednovati između dva pseudonima koji pripadaju istoj razini. On će biti učinkovit, ako će pravi identitet čvora biti izložen, ako je broj napada iste razine unutar vremena koje prelazi d vremena, čvorovi u procjeni i transakciji će biti praćeni. Analiza pokazuje da ovaj mehanizam ne samo da može zaštititi identitet istorazinske anonimnosti, već će identificirati i pratiti zlonamjerne napadače.In existing reputation system nodes usually adopt regular pseudonyms instead of true identities to gain the anonymity. However complete anonymity will cause watershed and Sybil attack, which look on system be out of control and break the fairness of the reputation system. This paper introduces the conditional anonymity mechanism to check the evaluation between anonymity nodes, evaluation between two nodes if not more than the several times, but not be evaluated between two pseudonyms belong to the same peer. It will be effective, otherwise, the node true identity will be exposed, if number of attacks of the peer within the time exceeds d times, nodes in the evaluation and transaction will be tracked. Analysis shows that this mechanism cannot only protect the identity of peer\u27s anonymity, but identify and track malicious attackers

The effective field theory approach to the strong coupling issue in f(T)f(T) gravity with a non-minimally coupled scalar field

The Hamiltonian analysis for $f(T)$ gravity implies the existence of at least one scalar-type degree of freedom (DoF). However, this scalar DoF of $f(T)$ gravity does not manifest in linear perturbations around a cosmological background, which indicates an underlying strong coupling problem. In this work we expand the scope by introducing an extra scalar field non-minimally coupled to $f(T)$ gravity, aiming to address or alleviate the aforementioned strong coupling problem. Employing the effective field theory (EFT) approach, we provide a class of torsional EFT forms up to second order operators, avoiding the Ostrogradsky ghost. To illustrate this phenomenon, we study a simple model and perform a detailed analysis of its linear scalar perturbations. The results demonstrate that the coupling terms in this toy model are necessary to avoid the initial degenerate situation. The complete avoidance of new constraints requires more coupling terms. Once this vanishing scalar DoF starts propagating in cosmological background at linear level, this phenomenon will demand a revisit of the strong coupling issue that arises in $f(T)$ gravity, particularly in the presence of matter coupling