The Central Symbiosis of Molecular Biology: Molecules in Mutualism.

As illustrated by the mitochondrion and the eukaryotic cell, little in biology makes sense except in light of mutualism. Mutualisms are persistent, intimate, and reciprocal exchanges; an organism proficient in obtaining certain benefits confers those on a partner, which reciprocates by conferring different benefits. Mutualisms (i) increase fitness, (ii) inspire robustness, (iii) are resilient and resistant to change, (iv) sponsor co-evolution, (v) foster innovation, and (vi) involve partners that are distantly related with contrasting yet complementary proficiencies. Previous to this work, mutualisms were understood to operate on levels of cells, organisms, ecosystems, and even societies and economies. Here, the concepts of mutualism are extended to molecules and are seen to apply to the relationship between RNA and protein. Polynucleotide and polypeptide are Molecules in Mutualism. RNA synthesizes protein in the ribosome and protein synthesizes RNA in polymerases. RNA and protein are codependent, and trade proficiencies. Protein has proficiency in folding into complex three-dimensional states, contributing enzymes, fibers, adhesives, pumps, pores, switches, and receptors. RNA has proficiency in direct molecular recognition, achieved by complementary base pairing interactions, which allow it to maintain, record, and transduce information. The large phylogenetic distance that characterizes partnerships in organismal mutualism has close analogy with large distance in chemical space between RNA and protein. The RNA backbone is anionic and self-repulsive and cannot form hydrophobic structural cores. The protein backbone is neutral and cohesive and commonly forms hydrophobic cores. Molecules in Mutualism extends beyond RNA and protein. A cell is a consortium of molecules in which nucleic acids, proteins, polysaccharides, phospholipids, and other molecules form a mutualism consortium that drives metabolism and replication. Analogies are found in systems such as stromatolites, which are large consortia of symbiotic organisms. It seems reasonable to suggest that 'polymers in mutualism relationships' is a useful and predictive definition of life

ACL Reconstruction Results in Alterations for Force Control Variability During Multidirectional Force Production

After anterior cruciate ligament (ACL) rupture most will undergo reconstructive surgery. Within the first year after surgery 25% of patients will re-tear their ACL. Most of those injured attempt to return to sports which include running and cutting. The ability to produce appropriate ground reaction forces may be crucial for the successful return to sports without re-injury. Understanding stability of multidirectional ground reaction force (mGRF) production in healthy and ACL reconstructed (ACL-r) patients can lend insight to the high instance of re-injury. Typically, stability has been measured using linear analyses, but these analyses cannot capture the subtle time varying changes that can occur. Recently, research using nonlinear techniques, such as the Lyapunov exponent (LyE), have been able to overcome these issues. Recent studies using this measure to quantify the stability of knee flexion during gait found that there are significant increases in LyE measured after ACL injury and reconstruction when compared to healthy control subjects. The purpose of this study was to understand the ability of those with ACL reconstruction to produce specific mGRFs stably. We hypothesized that there would be more instability, noted by greater LyE values, after ACL reconstruction when compared to healthy uninjured controls. Secondarily, we hypothesized that LyE values measured during the medial/lateral (ML) task would be greater compared to the anterior/posterior (AP) task. Our study included 7 (2M) healthy uninjured individuals and 2 (1M) who have undergone ACL reconstruction. We provided visual feedback of GRF production in the AP and ML direction to the subjects. LyE requires two input parameters time lag (tau) and embedding dimension (m), used to transform the AP and ML GRF into phase space. LyE was calculated using the Wolf algorithm. Largest LyE in bits/sec was reported as it indicates maximum divergence/instability of force production. ACL-r subjects had larger LyE values when compared to healthy uninjured controls. Additionally, the uninvolved limb of ACL-r subjects exhibited larger LyE values when compared to healthy uninjured controls. When comparing the ML and AP task there were no differences in all three limbs: healthy, involved, and uninvolved. While there was instability between groups there was no instability specific to direction of force production

Modeling Pine as a Carbon Sequestering Crop in Arkansas

Carbon Sequestration, Loblolly Pine, Carbon Offset, Carbon Policy, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy,

Increasing Profitability of Small Scale Orchard Producers through Optimizing Replacement Rate: The Case Study of Ghana

This study sets out to empirically estimate the optimum annual replacement rate and age of cocoa trees in order to maximize the net present value of four common cocoa production systems. The study examines the costs and returns of four common cocoa production systems in Ghana associated with changes in cocoa prices, fertilizer prices, inflation rates, and labor prices. While this study focuses on cocoa, the methodology is applicable to any perennial crop. This study uses empirical yield curves and cost of production data from Ghana to determine when and what percentage of a cocoa orchard should be replaced annually to maximize net present value of revenues over time. Successive versions of the model are solved to determine how input and output price changes affect optimal replacement rates and replacement ages. Producers in both high- and low-income countries are reluctant to cull still productive assets, such as trees that are diminishing in yield over time. The Excel based model developed in this study could provide extension personnel with a simple yet powerful tool to illustrate to producers the benefits of systematic tree replacement. This study provides strong evidence of the benefits of replacing trees at the optimal time and rate.Cocoa, Replacement Rate, Net Present Value (NPV), Production Economics, Q01, Q15, Q32,

Resistive flow in a weakly interacting Bose-Einstein condensate

We report the direct observation of resistive flow through a weak link in a weakly interacting atomic Bose-Einstein condensate. Two weak links separate our ring-shaped superfluid atomtronic circuit into two distinct regions, a source and a drain. Motion of these weak links allows for creation of controlled flow between the source and the drain. At a critical value of the weak link velocity, we observe a transition from superfluid flow to superfluid plus resistive flow. Working in the hydrodynamic limit, we observe a conductivity that is 4 orders of magnitude larger than previously reported conductivities for a Bose-Einstein condensate with a tunnel junction. Good agreement with zero-temperature Gross-Pitaevskii simulations and a phenomenological model based on phase slips indicate that the creation of excitations plays an important role in the resulting conductivity. Our measurements of resistive flow elucidate the microscopic origin of the dissipation and pave the way for more complex atomtronic devices.Comment: Version published in PR

A Time Lord, a Timeline and Legal Instruction

From online embeds to interactive displays, timelines can serve many purposes and tell powerful stories. In this session librarians team up with an archivist and a clinician to bring history to life, engage students, and preserve the scholarly and institutional milestones. A variety of tools for creating digital timelines and gathering content will be shared including TikiToki, TimeToast, and Piktochart. Comparisons will be given based on cost, technical limitations, collaborative potential, and general ease of use. Potential applications for timelines will also be shared in the form of examples including: a TimeToast embedded timeline tribute for individual faculty scholarship as a part of research guides a TikiToki multi-media timeline celebrating the growth of clinical and experiential learning programs over the course of 50 years a Piktochart timeline for classroom slides or printed display illustrating a series of significant trials Time permitting, a live demo will guide attendees through the creation of a timeline with one of the tools. This session will be of interest to technologists, librarians and faculty alike. Attendees will walk away with an overview of the tools available for making timelines, ideas for how they could be used for instructional purposes, and a guide including examples and resources

Modulation of Natural Killer Cell Cytotoxicity in Human Cytomegalovirus Infection: The Role of Endogenous Class I Major Histocompatibility Complex and a Viral Class I Homolog

Natural killer (NK) cells have been implicated in early immune responses against certain viruses, including cytomegalovirus (CMV). CMV causes downregulation of class I major histocompatibility complex (MHC) expression in infected cells; however, it has been proposed that a class I MHC homolog encoded by CMV, UL18, may act as a surrogate ligand to prevent NK cell lysis of CMV-infected cells. In this study, we examined the role of UL18 in NK cell recognition and lysis using fibroblasts infected with either wild-type or UL18 knockout CMV virus, and by using cell lines transfected with the UL18 gene. In both systems, the expression of UL18 resulted in the enhanced killing of target cells. We also show that the enhanced killing is due to both UL18-dependent and -independent mechanisms, and that the killer cell inhibitory receptors (KIRs) and CD94/NKG2A inhibitory receptors for MHC class I do not play a role in affecting susceptibility of CMV-infected fibroblasts to NK cell–mediated cytotoxicity

A Novel and Safe Approach to Simulate Cutting Movements Using Ground Reaction Forces

Control of shear ground reaction forces (sGRF) is important in performing running and cutting tasks as poor sGRF control has implications for those with knee injuries, such as anterior cruciate ligament (ACL) ruptures. The goal of this study was to develop a novel and safe task to evaluate control or accurate modulation of shear ground reaction forces related to those generated during cutting. Our approach utilized a force control task using real-time visual feedback of a subject’s force production and evaluated control capabilities through accuracy and divergence measurements. Ten healthy recreational athletes completed the force control task while force control via accuracy measures and divergence calculations was investigated. Participants were able to accurately control sGRF in multiple directions based on error measurements. Forces generated during the task were equal to or greater than those measured during a number of functional activities. We found no significant difference in the divergence of the force profiles using the Lyapunov Exponent of the sGRF trajectories. Participants using our approach produced high accuracy and low divergence force profiles and functional force magnitudes. Moving forward, we will utilize this task in at-risk populations who are unable to complete a cutting maneuver in early stages of rehabilitation, such as ACL deficient and newly reconstructed individuals, allowing insight into force control not obtainable otherwise

Brn3a regulates neuronal subtype specification in the trigeminal ganglion by promoting Runx expression during sensory differentiation

The transcription factor Brn3a, product of the pou4f1 gene, is expressed in most sensory neurons throughout embryogenesis. Prior work has demonstrated a role for Brn3a in the repression of early neurogenic genes; here we describe a second major role for Brn3a in the specification of sensory subtypes in the trigeminal ganglion (TG). Sensory neurons initially co-express multiple Trk-family neurotrophin receptors, but are later marked by the unique expression of TrkA, TrkB or TrkC. Maturation of these sensory subtypes is known to depend on the expression of Runx transcription factors. Newborn Brn3a knockout mice fail to express TrkC, which is associated in the TG with mechanoreceptors, plus a set of functional genes associated with nociceptor subtypes. In embryonic Brn3a-/- ganglia, the normal expression of Runx3 is never initiated in TrkC+ neurons, and Runx1 expression is greatly attenuated in TrkA+ nociceptors. These changes are accompanied by expanded expression of TrkB in neurons that abnormally express multiple Trks, followed by the loss of TrkC and TrkA expression. In transgenic embryos expressing a Brn3a-VP16 dominant transactivator, Runx3 mRNA expression is increased, suggesting that it is a direct regulatory target of Brn3a. Chromatin immunoprecipitation confirms that Brn3a binds in vivo to a conserved upstream enhancer element within histone H3-acetylated chromatin in the Runx3 locus. Together these data show that Brn3a acts upstream of the Runx factors, which then repress TrkB expression to allow establishment of the non-overlapping Trk receptor profiles and correct terminally differentiated phenotypes