Microfluidic systems: A new toolbox for pluripotent stem cells

Conventional culture systems are often limited in their ability to regulate the growth and differentiation of pluripotent stem cells. Microfluidic systems can overcome some of these limitations by providing defined growth conditions with user-controlled spatiotemporal cues. Microfluidic systems allow researchers to modulate pluripotent stem cell renewal and differentiation through biochemical and mechanical stimulation, as well as through microscale patterning and organization of cells and extracellular materials. Essentially, microfluidic tools are reducing the gap between in vitro cell culture environments and the complex and dynamic features of the in vivo stem cell niche. These microfluidic culture systems can also be integrated with microanalytical tools to assess the health and molecular status of pluripotent stem cells. The ability to control biochemical and mechanical input to cells, as well as rapidly and efficiently analyze the biological output from cells, will further our understanding of stem cells and help translate them into clinical use. This review provides a comprehensive insignt into the implications of microfluidics on pluripotent stem cell research.     

A general modeling and visualization tool for comparing different members of a group: application to studying tau-mediated regulation of microtubule dynamics

Background  

Innumerable biological investigations require comparing collections of molecules, cells or organisms to one another with respect to one or more of their properties. Almost all of these comparisons are performed manually, which can be susceptible to inadvertent bias as well as miss subtle effects. The development and application of computer-assisted analytical and interpretive tools could help address these issues and thereby dramatically improve these investigations.     

Argonaute-CLIP delineates versatile,functional RNAi networks in Aedes aegypti,a major vector of human viruses

1. Download : Download high-res image (207KB)
2. Download : Download full-size image

     

Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomised trial

Objective To assess whether exclusive and prolonged breast feeding reduces the risk of childhood asthma and allergy by age 6.5 years.Design Cluster randomised trial.Setting 31 Belarussian maternity hospitals and their affiliated polyclinics.Participants A total of 17 046 mother-infant pairs were enrolled, of whom 13 889 (81.5%) were followed up at age 6.5 years.Intervention Breastfeeding promotion intervention modelled on the WHO/UNICEF baby friendly hospital initiative.Main outcome measures International study of asthma and allergies in childhood (ISAAC) questionnaire and skin prick tests of five inhalant antigens.Results The experimental intervention led to a large increase in exclusive breast feeding at 3 months (44.3% v 6.4%; P<0.001) and a significantly higher prevalence of any breast feeding at all ages up to and including 12 months. The experimental group had no reduction in risks of allergic symptoms and diagnoses or positive skin prick tests. In fact, after exclusion of six sites (three experimental and three control) with suspiciously high rates of positive skin prick tests, risks were significantly increased in the experimental group for four of the five antigens.Conclusions These results do not support a protective effect of prolonged and exclusive breast feeding on asthma or allergy.Trial registration Current Controlled Trials ISRCTN37687716.     

Cytoskeletal confinement of CX3CL1 limits its susceptibility to proteolytic cleavage by ADAM10

CX₃CL1 is a unique chemokine that acts both as a transmembrane endothelial adhesion molecule and, upon proteolytic cleavage, a soluble chemoattractant for circulating leukocytes. The constitutive release of soluble CX₃CL1 requires the interaction of its transmembrane species with the integral membrane metalloprotease ADAM10, yet the mechanisms governing this process remain elusive. Using single-particle tracking and subdiffraction imaging, we studied how ADAM10 interacts with CX₃CL1. We observed that the majority of cell surface CX₃CL1 diffused within restricted confinement regions structured by the cortical actin cytoskeleton. These confinement regions sequestered CX₃CL1 from ADAM10, precluding their association. Disruption of the actin cytoskeleton reduced CX₃CL1 confinement and increased CX₃CL1–ADAM10 interactions, promoting the release of soluble chemokine. Our results demonstrate a novel role for the cytoskeleton in limiting membrane protein proteolysis, thereby regulating both cell surface levels and the release of soluble ligand.     

Information is a fitness enhancing resource

Here we provide a biologically relevant proof of the well‐known result from economics and statistical decision theory that having more information never reduces the expected payoff to a decision‐making agent. We then go on to illustrate this with an ecologically motivated example based on a model of growth under uncertain predation risk. Throughout we use the central result that the fitness (reproductive) value of information can never be negative to highlight conceptual inconsistencies in the ecological literature on information use.     

Organization of ‘special’ parenchymal cells underlying the midgut in some Barnacles

The layer of cells immediately underlying the midgut in the Balanidae contains unusual structural features which distinguish it from the remaining parenchyma. The cells, in general, are expanded at their distal end (away from the midgut), narrow at the proximal end (towards the midgut) and are referred to in this study as morphologically polarized cells. The narrow portion contains numerous aligned microtubules which pass through holes in perpendicularly oriented membranous sacs. This portion of the cell continues toward the midgut between layers of muscle across hemolymphatic space and terminates within infolding at the basal end of the intestinal epithelial cells. The distal, expanded portion of the cell contains many dense, lamellar bodies. S.E.M. X-ray spectra of the lamellar bodies show predominant peaks for zinc and phosphorus. Some functional implications of the organization and location of these cells are discussed.     

The ecology of information: an overview on the ecological significance of making informed decisions

Information is characterized as the reduction of uncertainty and by a change in the state of a receiving organism. Thus, organisms can acquire information about their environment that reduces uncertainty and increases their likelihood of choosing a best‐matching strategy. We define the ecology of information as the study of how organisms acquire and use information in decision‐making and its significance for populations, communities, landscapes and ecosystems. As a whole, it encompasses the reception and processing of information, decision‐making, and the ecological consequences of making informed decisions. The first two stages constitute the domains of, e.g. sensory ecology and behavioral ecology. The exploration of the consequences of information use at larger spatial and temporal scales in ecology has lagged behind these other disciplines. In our overview we characterize information, discuss statistical decision theory as a quantitative framework to analyze information and decision‐making, and discuss potential ecological ramifications. Rather than attempt a cursory review of the enormity of the scope of information we highlight information use in development, breeding habitat selection, and interceptive eavesdropping on alarm calls. Through these topics we discuss specific examples of ecological information use and the emerging ecological consequences. We emphasize recurring themes: information is collected from multiple sources, over varying temporal and spatial scales, and in many cases links heterospecifics to one another. We conclude by breaking from specific ecological contexts to explore implications of information as a central organizing principle, including: information webs, information as a component of the niche concept, and information as an ecosystem process. With information having such an enormous reach in ecology we further cast a spotlight on the potential harmful effects of anthropogenic noise and info‐disruption.