Multiplexing information flow through dynamic signalling systems

We consider how a signalling system can act as an information hub by multiplexing information arising from multiple signals. We formally define multiplexing, mathematically characterise which systems can multiplex and how well they can do it. While the results of this paper are theoretical, to motivate the idea of multiplexing, we provide experimental evidence that tentatively suggests that the NF-κB transcription factor can multiplex information about changes in multiple signals. We believe that our theoretical results may resolve the apparent paradox of how a system like NF-κB that regulates cell fate and inflammatory signalling in response to diverse stimuli can appear to have the low information carrying capacity suggested by recent studies on scalar signals. In carrying out our study, we introduce new methods for the analysis of large, nonlinear stochastic dynamic models, and develop computational algorithms that facilitate the calculation of fundamental constructs of information theory such as Kullback–Leibler divergences and sensitivity matrices, and link these methods to a new theory about multiplexing information. We show that many current models such as those of the NF-κB system cannot multiplex effectively and provide models that overcome this limitation using post-transcriptional modifications

Continuous lithium mining from aqueous resources by an adsorbent filter with a 3D polymeric nanofiber network infused with ion sieves

© 2016 Elsevier B.V. Electrospun composite nanofiber (NF) was fabricated and employed as an adsorbent membrane filter in a continuous Li+ mining process from seawater. The filter was composed of a hydrophilic polyacrylonitrile (PAN) matrix infused with lithium ion sieves (LIS) H1.6Mn1.6O4. Characterization of the LIS/PAN NF confirmed its favorable structural and surface properties for effective Li+ adsorption. The LIS/PAN NF was mechanically suitable as a microfiltration membrane with high water flux and low pressure requirement. Breakthrough experiments at varied feed concentrations (Cf), seawater flowrates (F), and NF thicknesses (Z) revealed the dynamic adsorption behavior of the filter. The seawater residence time was most critical and must be kept ⩾0.12 min at any given Cf and Z to maximize the Li+ capacity of the filter. This can be conveniently achieved by adjusting the F of the process. Analogous to a packed bed system, the predictive power of nine breakthrough models were determined through non-linear regression analyses. Results reveal that bed-depth-space-time, Bohart-Adams (BA) and Thomas models adequately predicted the performance of the filter albeit BA exhibited the best agreement. Meanwhile, Wolborska failed to converge with any of the experimental results while Yoon-Nelson, Wang, Clark, dose-response, and modified dose-response were too simple to provide any meaningful information. Cycled Li+ adsorption-desorption runs successfully collected and concentrated Li+ in a mild acid stripping solution. After ten cycles, Li+ was separated 155–1552 times more efficiently than Na+, K+, Mg2+ and Ca2+. Overall results demonstrate the potential of LIS/PAN NF as an adsorbent membrane filter for continuous Li+ mining from aqueous resources

Antagonic activities of Trypanosoma cruzi metacaspases affect the balance between cell proliferation, death and differentiation

Metacaspases are distant relatives of animal caspases present in plants, fungi and protozoa. At variance with caspases, metacaspases exhibit stringent specificity for basic amino-acid residues and are absolutely dependent on millimolar concentrations of calcium. In the protozoan parasite Trypanosoma cruzi, metacaspases have been suggested to be involved in an apoptosis-like phenomenon upon exposure of the parasite to fresh human serum (FHS). Nuclear relocalization of metacaspases was observed after FHS treatment and overexpression of metacaspase-5 led to enhanced sensitivity to this stimulus. Here we report some biochemical properties of T. cruzi metacaspases. Performing fluorescent-activated cell sorting (FACS) analysis of epimastigotes inducibly overexpressing metacaspase-3, we demonstrate a role for this metacaspase in cell cycle progression, protection of epimastigotes from naturally occurring cell death and differentiation to infective metacyclic trypomastigotes. We also show that regulation of metacaspase-3 activity is important for cell cycle completion inside the mammalian host. On the other hand, inducible overexpression of metacaspase-5 lacking its C-terminal domain caused an apoptotic-like response. These results suggest that the two T. cruzi metacaspases could play an important role in the life cycle and bring to light the close relationship between cell division, death and differentiation in this ancient unicellular eukaryote. © 2012 Macmillan Publishers Limited All rights reserved.Fil: Laverriere, Marc. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Cazzulo, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Alvarez, Vanina Eder. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin