A spiral microfluidic device for rapid sorting,trapping,and long-term live imaging of Caenorhabditis elegans embryos

Caenorhabditis elegans embryos have been widely used to study cellular processes and developmental regulation at early stages.However,most existing microfluidic devices focus on the studies of larval or adult worms rather than embryos.To accurately study the real-time dynamics of embryonic development under different conditions,many technical barriers must be overcome;these can include single-embryo sorting and immobilization,precise control of the experimental environment,and long-term live imaging of embryos.This paper reports a spiral microfluidic device for effective sorting,trapping,and long-term live imaging of single C.elegans embryos under precisely controlled experimental conditions.The device successfully sorts embryos from a mixed population of C.elegans at different developmental stages via Dean vortices generated inside a spiral microchannel and traps the sorted embryos at single-cell resolution through hydrodynamic traps on the sidewall of the spiral channel for long-term imaging.Through the well-controlled microenvironment inside the microfluidic device,the response of the trapped C.elegans embryos to mechanical and chemical stimulation can be quantitatively measured.The experimental results show that a gentle hydrodynamic force would induce faster growth of embryos,and embryos developmentally arrested in the high-salinity solution could be rescued by the M9 buffer.The microfluidic device provides new avenues for easy,rapid,high-content screening of C.elegans embryos.

Factors attracting Chinese Generation Y in the smartphone application marketplace

Smartphone applications （apps） are becoming in- creasingly popular all over the world, particularly in the Chi- nese Generation Y population; however, surprisingly, only a small number of studies on app factors valued by this im- portant group have been conducted. Because the competition among app developers is increasing, app factors that attract users＇ attention are worth studying for sales promotion. This paper examines these factors through two separate studies. In the first study, i.e., Experiment 1, which consists of a survey, perceptual rating and verbal protocol methods are employed, and 90 randomly selected app websites are rated by 169 expe- rienced smartphone users according to app attraction. Twelve of the most rated apps （six highest rated and six lowest rated） are selected for further investigation, and 11 influential fac- tors that Generation Y members value are listed. A second study, i.e., Experiment 2, is conducted using the most and least rated app websites from Experiment 1, and eye tracking and verbal protocol methods are used. The eye movements of 45 participants are tracked while browsing these websites, providing evidence about what attracts these users＇ attention and the order in which the app components are viewed. The results of these two studies suggest that Chinese Generation Y is a content-centric group when they browse the smart- phone app marketplace. Icon, screenshot, price, rating, and name are the dominant and indispensable factors that influ- ence purchase intentions, among which icon and screenshot should be meticulously designed. Price is another key fac- tor that drives Chinese Generation Y＇s attention. The recom- mended apps are the least dominant element. Design sugges- tions for app websites are also proposed. This research has important implications.

Pyk2 suppresses contextual fear memory in an autophosphorylation-independent manner

Clustered protocadherins(Pcdhs)are a large family of cadherin-like cell adhesion proteins that are central for neurite selfavoidance and neuronal connectivity in the brain.Their downstream nonreceptor tyrosine kinase Pyk2(proline-rich tyrosine kinase 2,also known as Ptk2b,Cakb,Raftk,Fak2,and Cadtk)is predominantly expressed in the hippocampus.We constructed Pyk2-null mouse lines and found that these mutant mice showed enhancement in contextual fear memory,without significant change in auditory-cued and spatial-referenced learning and memory.In addition,by preparing Y402F mutant mice,we observed that Pyk2 suppressed contextual fear memory in an autophosphorylation-independent manner.Moreover,using high-throughput RNA sequencing,we found that immediate early genes,such as Npas4,cFos,Zif268/Egr1,Arc,and Nr4a1,were enhanced in Pyk2-null mice.We further showed that Pyk2 disruption affected pyramidal neuronal complexity and spine dynamics.Thus,we demonstrated that Pyk2 is a novel fear memory suppressor molecule and Pyk2-null mice provide a model for understanding fearrelated disorders.These findings have interesting implications regarding dysregulation of the Pcdh–Pyk2 axis in neuropsychiatric disorders.