Broadening the Gene Pool: The Value of the Humanities Future Success

Readers are asked, “How can we hope to imagine our future, and more importantly, address what it brings, if we do so using frameworks defined only by our present and most immediate needs?” Art historian Michael Grillo that study of the human­ities ensures our best chances of creative thought, cultural growth, and meaningful surviva

Autonomy, Identity and the Right to Die: A Qualitative Study of Medically Assisted Death Attitudes in the Canadian Context

In Canada, medically-assisted death has been legal since June 17th, 2016, when Bill C-14 received royal assent in the Canadian legislature. The legal proceedings around MAiD in Canada have been supported by non-governmental organizations and advocacy groups, for and against MAiD. The legalization of MAiD is the culmination of decades of organization and advocacy, supported by generally favourable public opinion. In this dissertation, the author develops a theory to explain why individuals increasingly identify with pro-MAiD beliefs. The study consequently makes two contributions to the sociological literature; 1) it reveals the connections between autonomy, care work, humanism, and pro-MAiD identities; 2) it features the development of a critical realist social psychology, focused on the reflexivity and the creation of personal moral identity. Specifically, the study is focused on how lived experiences of death including caregiving, bereavement, and/or serious illness, inform pro-MAiD beliefs for volunteers and other actors involved with pro-euthanasia organizations. The author theorizes that pro-MAiD identities are centred primarily on the principle of autonomy, which is couched within humanist and naturalist cultural frameworks, and enacted through care work. Specifically, over the course of care work, volunteers and other movement participants witnessed what they perceived as a fundamental loss of identity by the people for whom they were caring. The loss of identity witnessed by these carers motivated them to pursue greater autonomy over their own deaths, and to therefore avoid the deterioration they witnessed in others. It also motivated them to act as social carriers for the dissemination of norms associated with pro-MAiD political stances

Modulation of neuronal ryanodine receptor-mediated calcium signaling by calsenilin

A dissertation in Cell Biology and Biophysics and Molecular Biology and BiochemistryIncludes bibliographical references (pages 92-105)Calsenilin is calcium (Ca2+) ion Ca2+ binding protein found in the nucleus, plasma membrane, and endoplasmic reticulum of neuronal cells. Calsenilin was first found to interact with two proteins involved in early-onset familial Alzheimer disease (AD), presenilin 1 and presenilin 2. Several studies have shown overexpression of calsenilin to alter Ca2+ signaling and cell viability in several neuronal cell models of AD. In this study, we show that calsenilin directly interacts with the ryanodine receptor (RyR) modulating Ca2+ release from this intracellular Ca2+-activated Ca2+ release channel. Co-expression, co-localization, and protein-protein interaction of calsenilin and RyR in primary neurons and in central nervous system tissue were determined using immunoblotting, immunohistochemistry and co-immunoprecipitation. Mechanisms of intracellular Ca2+- signaling controlled by the interaction of calsenilin and RyR, including changes in the release of Ca2+ from intracellular stores, were measured with single channel electrophysiology and live-cell optical imaging techniques. Immunohistochemical studies showed a high degree of co-localization between calsenilin and the RyR in neurons of the central nervous system. Additionally, iv successful immunoprecipitation of a RyR-calsenilin protein complex from brain tissue provided evidence of a functional interaction. Using electrophysiological and Ca2+ imaging techniques the modulatory effects of calsenilin on Ca2+ release in a single RyR channel or in a cellular system with a population of RyR channels, respectively, whereby RyR-mediated intracellular Ca2+ release by calsenilin was determined under physiological and pathophysiological intracellular Ca2+ concentrations. Calsenilin directly interacts with the RyR, modulating Ca2+ induced Ca2+ release (CICR) pathways in neuronal cells. Further characterization of this interaction and its pharmacological and molecular biological control could provide insight into altered Ca2+ signaling in neurodegenerative and other diseases controlled by CICR and aid in developing novel alternative therapies using these newly identified mechanisms as targets.Introduction -- Materials and methods -- Results -- Discussion -- References -- Vit

Structure and spacing of cellulose microfibrils in woody cell walls of dicots

The structure of cellulose microfibrils in situ in wood from the dicotyledonous (hardwood) species cherry and birch, and the vascular tissue from sunflower stems, was examined by wide-angle X-ray and neutron scattering (WAXS and WANS) and small-angle neutron scattering (SANS). Deuteration of accessible cellulose chains followed by WANS showed that these chains were packed at similar spacings to crystalline cellulose, consistent with their inclusion in the microfibril dimensions and with a location at the surface of the microfibrils. Using the Scherrer equation and correcting for considerable lateral disorder, the microfibril dimensions of cherry, birch and sunflower microfibrils perpendicular to the [200] crystal plane were estimated as 3.0, 3.4 and 3.3 nm respectively. The lateral dimensions in other directions were more difficult to correct for disorder but appeared to be 3 nm or less. However for cherry and sunflower, the microfibril spacing estimated by SANS was about 4 nm and was insensitive to the presence of moisture. If the microfibril width was 3 nm as estimated by WAXS, the SANS spacing suggests that a non-cellulosic polymer segment might in places separate the aggregated cellulose microfibrils

Synaptic boutons sizes are tuned to best fit their physiological performances

To truly appreciate the myriad of events which relate synaptic function and vesicle dynamics, simulations should be done in a spatially realistic environment. This holds true in particular in order to explain as well the rather astonishing motor patterns which we observed within in vivo recordings which underlie peristaltic contractionsas well as the shape of the EPSPs at different forms of long-term stimulation, presented both here, at a well characterized synapse, the neuromuscular junction (NMJ) of the Drosophila larva (c.f. Figure 1). To this end, we have employed a reductionist approach and generated three dimensional models of single presynaptic boutons at the Drosophila larval NMJ. Vesicle dynamics are described by diffusion-like partial differential equations which are solved numerically on unstructured grids using the uG platform. In our model we varied parameters such as bouton-size, vesicle output probability (Po), stimulation frequency and number of synapses, to observe how altering these parameters effected bouton function. Hence we demonstrate that the morphologic and physiologic specialization maybe a convergent evolutionary adaptation to regulate the trade off between sustained, low output, and short term, high output, synaptic signals. There seems to be a biologically meaningful explanation for the co-existence of the two different bouton types as previously observed at the NMJ (characterized especially by the relation between size and Po), the assigning of two different tasks with respect to short- and long-time behaviour could allow for an optimized interplay of different synapse types. We can present astonishing similar results of experimental and simulation data which could be gained in particular without any data fitting, however based only on biophysical values which could be taken from different experimental results. As a side product, we demonstrate how advanced methods from numerical mathematics could help in future to resolve also other difficult experimental neurobiological issues

Synaptic bouton sizes are tuned to best fit their physiological performances : poster presentation from Twentieth Annual Computational Neuroscience Meeting: CNS*2011, Stockholm, Sweden, 23 - 28 July 2011

Poster presentation from Twentieth Annual Computational Neuroscience Meeting: CNS*2011 Stockholm, Sweden. 23-28 July 2011. To truly appreciate the myriad of events which relate synaptic function and vesicle dynamics, simulations should be done in a spatially realistic environment. This holds true in particular in order to explain the rather astonishing motor patterns presented here which we observed within in vivo recordings which underlie peristaltic contractions at a well characterized synapse, the neuromuscular junction (NMJ) of the Drosophila larva. To this end, we have employed a reductionist approach and generated three dimensional models of single presynaptic boutons at the Drosophila larval NMJ. Vesicle dynamics are described by diffusion-like partial differential equations which are solved numerically on unstructured grids using the uG platform. In our model we varied parameters such as bouton-size, vesicle output probability (Po), stimulation frequency and number of synapses, to observe how altering these parameters effected bouton function. Hence we demonstrate that the morphologic and physiologic specialization maybe a convergent evolutionary adaptation to regulate the trade off between sustained, low output, and short term, high output, synaptic signals. There seems to be a biologically meaningful explanation for the co-existence of the two different bouton types as previously observed at the NMJ (characterized especially by the relation between size and Po),the assigning of two different tasks with respect to short- and long-time behaviour could allow for an optimized interplay of different synapse types. As a side product, we demonstrate how advanced methods from numerical mathematics could help in future to resolve also other difficult experimental neurobiological issues

Hemicellulose binding and the spacing of cellulose microfibrils in spruce wood

Cellulose microfibrils in conifers, as in other woody materials, are aggregated into loose bundles called macrofibrils. The centre-to-centre spacing of the microfibrils within these macrofibrils can be estimated from the position of a broad diffraction peak in small-angle neutron scattering (SANS) after deuteration. A known spacing of 3.0 nm, increasing with moisture content, is consistent with direct microfibril to microfibril contact. However recent evidence indicates that conifer microfibrils are partially coated with bound xylan chains, and possibly with lignin and galactoglucomannan, implying a wider centre-to-centre spacing as found in angiosperm wood. Delignification of spruce wood allowed a weak SANS peak to be observed without measurable change in spacing. By deuterating spruce wood in mildly alkaline D2O and then re-equilibrating with ambient H2O, deuterium atoms were trapped in a position that gave a 3.8 nm microfibril spacing under dry conditions as in angiosperm wood, instead of the 3.0 nm spacing normally observed in conifers. After conventional vapour deuteration of spruce wood a minor peak at 3.8 nm could be fitted in addition to the 3.0 nm peak. These observations are consistent with some microfibril segments being separated by bound xylan chains as in angiosperms, in addition to the microfibril segments that are in direct contact

Formation and structure of slightly anionically charged nanoemulsions obtained by the phase inversion concentration (PIC) method

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.While nanoemulsions (10–200 nm) are not thermodynamically stable systems they can exhibit quite long term stability. In this paper oil/surfactant mixtures, containing diethylhexyl carbonate/phenoxyethanol/parabens as oil and polyglyceryl-4 laurate/dilauryl citrate as surfactant, form nanoemulsions simply by dilution with water, i.e. by means of the phase inversion concentration (PIC) method. In order to study this highly interesting phenomenon an investigation at constant oil-to-surfactant (O/S) ratio was done by means of viscosity, conductivity, and UV/Vis-transmittance measurements. This phase study as a function of the dilution by water shows that at an intermediate water content a two-phase system of bicontinuous structure is formed, which exhibits a very pronounced viscosity and conductivity maximum shortly before the homogeneous nanoemulsion phase is reached. In the same region SANS shows a high degree of ordering of this bicontinuous structure. SANS and cryo-TEM investigations of the nanoemulsion regime show an increasing average size with dilution and, more interestingly, the presence of two populations with different average particle sizes around 10–15 nm and 25–40 nm. The relative proportion of each population depends on the amount of added water, leading to an average growth of the particle size with increasing dilution

Discordant Population Structure Among Rhizobium Divided Genomes and Their Legume Hosts

Symbiosis often occurs between partners with distinct life history characteristics and dispersal mechanisms. Many bacterial symbionts have genomes comprising multiple replicons with distinct rates of evolution and horizontal transmission. Such differences might drive differences in population structure between hosts and symbionts and among the elements of the divided genomes of bacterial symbionts. These differences might, in turn, shape the evolution of symbiotic interactions and bacterial evolution. Here we use whole genome resequencing of a hierarchically structured sample of 191 strains of Sinorhizobium meliloti collected from 21 locations in southern Europe to characterize population structures of this bacterial symbiont, which forms a root nodule symbiosis with the host plant Medicago truncatula. S. meliloti genomes showed high local (within-site) variation and little isolation by distance. This was particularly true for the two symbiosis elements, pSymA and pSymB, which have population structures that are similar to each other, but distinct from both the bacterial chromosome and the host plant. Given limited recombination on the chromosome, compared to the symbiosis elements, distinct population structures may result from differences in effective gene flow. Alternatively, positive or purifying selection, with little recombination, may explain distinct geographical patterns at the chromosome. Discordant population structure between hosts and symbionts indicates that geographically and genetically distinct host populations in different parts of the range might interact with genetically similar symbionts, potentially minimizing local specialization

Live Imaging of Type I Collagen Assembly Dynamics in Osteoblasts Stably Expressing GFP and mCherry-Tagged Collagen Constructs

Type I collagen is the most abundant extracellular matrix protein in bone and other connective tissues and plays key roles in normal and pathological bone formation as well as in connective tissue disorders and fibrosis. Although much is known about the collagen biosynthetic pathway and its regulatory steps, the mechanisms by which it is assembled extracellularly are less clear. We have generated GFPtpz and mCherry-tagged collagen fusion constructs for live imaging of type I collagen assembly by replacing the α2(I)-procollagen N-terminal propeptide with GFPtpz or mCherry. These novel imaging probes were stably transfected into MLO-A5 osteoblast-like cells and fibronectin-null mouse embryonic fibroblasts (FN-null-MEFs) and used for imaging type I collagen assembly dynamics and its dependence on fibronectin. Both fusion proteins co-precipitated with α1(I)-collagen and remained intracellular without ascorbate but were assembled into α1(I) collagen-containing extracellular fibrils in the presence of ascorbate. Immunogold-EM confirmed their ultrastuctural localization in banded collagen fibrils. Live cell imaging in stably transfected MLO-A5 cells revealed the highly dynamic nature of collagen assembly and showed that during assembly the fibril networks are continually stretched and contracted due to the underlying cell motion. We also observed that cell-generated forces can physically reshape the collagen fibrils. Using co-cultures of mCherry- and GFPtpz-collagen expressing cells, we show that multiple cells contribute collagen to form collagen fiber bundles. Immuno-EM further showed that individual collagen fibrils can receive contributions of collagen from more than one cell. Live cell imaging in FN-null-MEFs expressing GFPtpz-collagen showed that collagen assembly was both dependent upon and dynamically integrated with fibronectin assembly. These GFP-collagen fusion constructs provide a powerful tool for imaging collagen in living cells and have revealed novel and fundamental insights into the dynamic mechanisms for the extracellular assembly of collagen