HB-EGF Is Necessary and Sufficient for Müller Glia Dedifferentiation and Retina Regeneration

SummaryMüller glia (MG) dedifferentiation into a cycling population of multipotent progenitors is crucial to zebrafish retina regeneration. The mechanisms underlying MG dedifferentiation are unknown. Here we report that heparin-binding epidermal-like growth factor (HB-EGF) is rapidly induced in MG residing at the injury site and that pro-HB-EGF ectodomain shedding is necessary for retina regeneration. Remarkably, HB-EGF stimulates the formation of multipotent MG-derived progenitors in the uninjured retina. We show that HB-EGF mediates its effects via an EGFR/MAPK signal transduction cascade that regulates the expression of regeneration-associated genes, like ascl1a and pax6b. We also uncover an HB-EGF/Ascl1a/Notch/hb-egfa-signaling loop that helps define the zone of injury-responsive MG. Finally, we show that HB-EGF acts upstream of the Wnt/β-catenin-signaling cascade that controls progenitor proliferation. These data provide a link between extracellular signaling and regeneration-associated gene expression in the injured retina and suggest strategies for stimulating retina regeneration in mammals

Graceful Degradation An Airborne Surveillance Radar Perspective

Active electronically scanned antenna (AESA)-based radars imbibe the desirable feature of ‘graceful degradation’. Such radars use miniaturised transmit-receive (TR) modules and a failure of few modules does not lead to failure of the mission. For example, in AESA-based ground MTI radar, failure of a few modules does not affect the array performance. In such a case, the static ground clutter is centred on zero frequency does not have a motion dependent Doppler spread. However, in airborne AESA radars, the ground clutter has an angle dependent Doppler frequency due to the platform motion and clutter leaking in through antenna side-lobes. Hence, the antenna side lobe levels dictate the side lobe clutter against which target detection is to be performed. The detection performance is governed by the signal to interference plus noise ratio (SINR). For Airborne surveillance radar the effect of random and systematic failures of TR modules and their effect on SINR is characterised. It is shown that single channel processing does not effectively provide the graceful degradation feature as the SINR loss due to failures is significant. However, the effect of systematic failure on SINR loss is less as compared to random failures. An effective scheme for feeding the array is also proposed

A Study on Stress Level, Happiness, Challenges, and Emotional Bonds of Parents having Children with Disabilities Availing Services at NIEPMD, Chennai

Being a parent is normally a joyous occasion and creating emotional bond between parents and their children is special, but in certain situations, lives of parents\u27 are plagued with challenges and are concerned about their ability to maintain their child\u27s physical, emotional, or economic well-being. It is very important to understand as how it is like to be a parent, because this helps to enhance the wellbeing of both parents and their children, especially if the child born is having disabilities. The study here consisting of equal distribution of male and female (N =100, Male = 50 and female = 50) coming to NIEPMD for rehabilitation services were taken as samples to find out stress level of parents of children having disabilities based on gender, based on age of the parent, based on the educational qualification of the parent, based the diagnosis of the children having disabilities. The Parental Stress Scale (PSS) questionnaire developed by Berry & Jones (1995) is a standardized scale and was used to assess parental stress. The researchers obtained due permission to use the scale from the author. The findings of the study revealed that 63% of the parents are having high level of stress in particular female parent are experiencing high level of stress (33%). Findings based on age shows that 35% of parents aged between 31-40 are having high level of stress, based on educational qualification of the parent 27% of the parents who completed under graduation are having high level of stress and based on the diagnosis of the children 25% of the parents having children diagnosed with Autism Spectrum Disorder are having high level of stress. The result implicated that parents having children with Autism Spectrum Disorder are having high level of stress. Understanding these fundamental results and trends allows practitioners and researchers to develop customized interventions and support methods to promote positive parenting experiences and improve the well-being of parents and children

Structural insights into the mechanisms of membrane binding and oligomerization of a bacterial pore-forming toxin

Perfringolysin O (PFO), a cytolytic toxin from by the pathogenic bacterium Clostridium perfringens, perforates mammalian cell membranes by forming large aqueous pores. Secreted as water-soluble monomers, the toxin molecules bind to cholesterol-containing membranes, form large, circular oligomeric complexes on the membrane surface and then insert into the bilayer to create pores with diameters near 300 Ã. Using multiple independent fluorescence techniques as primary tools, the mechanisms of PFO membrane binding and oligomerization have been identified. Domain 4 (D4) of the protein interacts first with the membrane and is responsible for cholesterol recognition. Remarkably, only the short hydrophobic loops at the tip of the D4 β-sandwich are exposed to the bilayer interior, while the remainder of D4 projects from the membrane surface. Thus, a very limited interaction of D4 with the bilayer core appears to be sufficient to accomplish cholesterol recognition and initial PFO binding to the membrane. Upon PFO membrane binding, a structural element in domain 3 (D3) of the molecule moves to expose the edge of a previously-hidden β-strand that forms the monomer-monomer interface. The β-strands that form the interface each contain a single aromatic residue, and these aromatics appear to stack to align the transmembrane β-hairpins of adjacent monomers in the proper register for insertion. Membrane-dependent structural rearrangements are thus required to initiate and regulate PFO oligomerization. Fluorescence resonance energy transfer measurements reveal that the elongated toxin monomer arrives at the membrane in an Âend-on orientation, with its long axis oriented nearly perpendicular to the plane of the membrane bilayer. This orientation is largely retained even after monomer association to form a prepore complex. In particular, the D3 polypeptide segments that form the transmembrane β-hairpins remain far above the membrane surface both at the membrane-bound monomer and prepore stages of pore formation. However, upon pore formation, the height of the oligomeric complex above the membrane surface is significantly reduced. The major topographical changes that occur during the prepore-to-pore transition of the PFO oligomer, therefore appears to result primarily from a collapsing of the extended domain 2 (D2) conformation in the monomer

Language use in education and primary schooling attainment: evidence from a natural experiment in Ethiopia

The extensive use of foreign languages in schooling might have an important role to play in the poor educational outcomes observed on the African continent. Exploiting the Language policy change of 1994 in Ethiopia as a natural experiment, we estimate the effects of provision of mother tongue instruction on the largest ethnic group in the country. Our results suggest that provision of mother tongue education led to an increase of 0.75 to 1 year of primary schooling in the affected cohort. Moreover the entire increase in the years of schooling can be attributed to the intensive margin of education. The language policy change, conditional on enrolment, increased the percentage of people completing 6 years or more of schooling by 31%. Applying our findings to a set of African countries shows that even after accounting for the costs of provision, introduction of mother tongue instruction imply potentially large benefits and increases the percentage of population completing primary schooling by as much as 15% points. These finding have important policy implications at a time when surging enrolment rates and already stretched educational budgets in the African continent imply need for solutions which can increase the quality of education without requiring huge capital or infrastructural outlays

Effect of substrate stiffness on early human embryonic stem cell differentiation

Background: The pluripotency and self renewing properties of human embryonic stem cells (hESC) make them a valuable tool in the fields of developmental biology, pharmacology and regenerative medicine. Therefore, there exists immense interest in devising strategies for hESC propagation and differentiation. Methods involving simulation of the native stem cell microenvironment, both chemical and physical, have received a lot of attention in recent years. Equally important is evidence that cells can also sense the mechanical properties of their microenvironment. In this study, we test the hypothesis that hESCs accept mechanical cues for differentiation from the substrate by culturing them on flexible polydimethylsiloxane (PDMS) of varying stiffness. Results: PDMS substrates were prepared using available commercial formulations and characterized for stiffness, surface properties and efficiency of cell attachment and proliferation. Across different substrate stiffness, cell numbers, cell attachment and cell surface area were found to be similar. Expression of pluripotency markers decreased with increased time in culture across all PDMS substrates of varying stiffness. Analysis of gene expression of differentiation markers indicates that the differentiation process becomes less stochastic with longer culture times. Conclusions: We evaluated the utility of PDMS substrates for stem cell propagation and substrate mediated differentiation. The stiffness affected gene expression of pluripotent and differentiation markers with results indicating that these substrate systems could potentially be used to direct hESC fate towards early mesodermal lineages. This study suggests that coupled with soluble factors, PDMS substrates could potentially be useful in generating defined populations of differentiated cells.Engineering and Applied Science

In silico selection of an aptamer to estrogen receptor alpha using computational docking employing estrogen response elements as aptamer-alike molecules

Aptamers, the chemical-antibody substitute to conventional antibodies, are primarily discovered through SELEX technology involving multi-round selections and enrichment. Circumventing conventional methodology, here we report an in silico selection of aptamers to estrogen receptor alpha (ERα) using RNA analogs of human estrogen response elements (EREs). The inverted repeat nature of ERE and the ability to form stable hairpins were used as criteria to obtain aptamer-alike sequences. Near-native RNA analogs of selected single stranded EREs were modelled and their likelihood to emerge as ERα aptamer was examined using AutoDock Vina, HADDOCK and PatchDock docking. These in silico predictions were validated by measuring the thermodynamic parameters of ERα -RNA interactions using isothermal titration calorimetry. Based on the in silico and in vitro results, we selected a candidate RNA (ERaptR4; 5′-GGGGUCAAGGUGACCCC-3′) having a binding constant (Ka) of 1.02 ± 0.1 × 108 M−1 as an ERα-aptamer. Target-specificity of the selected ERaptR4 aptamer was confirmed through cytochemistry and solid-phase immunoassays. Furthermore, stability analyses identified ERaptR4 resistant to serum and RNase A degradation in presence of ERα. Taken together, an efficient ERα-RNA aptamer is identified using a non-SELEX procedure of aptamer selection. The high-affinity and specificity can be utilized in detection of ERα in breast cancer and related diseases