Testing metabolic theories

Metabolism is the process by which individual organisms acquire energy and materials from their environment and use them for maintenance, differentiation, growth, and reproduction. There has been a recent push to build an individual-based metabolic underpinning into ecological theory—that is, a metabolic theory of ecology. However, the two main theories of individual metabolism that have been applied in ecology—Kooijman’s dynamic energy budget (DEB) theory and theWest, Brown, and Enquist (WBE) theory— have fundamentally different assumptions. Surprisingly, the core assumptions of these two theories have not been rigorously compared from an empirical perspective. Before we can build an understanding of ecology on the basis of individual metabolism, we must resolve the differences between these theories and thus set the appropriate foundation. Here we compare the DEB and WBE theories in detail as applied to ontogenetic growth and metabolic scaling, from which we identify circumstances where their predictions diverge most strongly. Promising experimental areas include manipulative studies of tissue regeneration, body shape, body condition, temperature, and oxygen. Much empirical work designed specifically with DEB and WBE theory in mind is required before any consensus can be reached on the appropriate theoretical basis for a metabolic theory of ecology

Communication Scholarship and the Quest for Open Access

The advent of black, green, and gold open access publication models poses unique questions for scholars of communication. Plato’s (1956) classic critique of writing in the legend of Theuth and Thamus warned that the printed word “rolls about all over the place, falling into the hands of those who have no concern with it” (pp. 69–70). More than two 2 millennia later, scholars and administrators at all levels of the discipline face just such a phenomenon. As scholars of cyberspace debate whether “information wants to be free” (Levy, 2014), a communication perspective involves consideration of the importance of authorship and attribution amid an ever-shifting array of digital publishing options and subversions. The purpose of this study is to investigate the ongoing transformation of academic publishing by examining black, green, and gold open access models, the responses of the communication discipline, and ongoing questions surrounding the nature and extent of accessibility. As access options for research and publication continue to evolve, this study hopes to provide coordinates for administrators seeking to navigate questions concerning the what, how, and why of communication scholarship in a digital age

Comparative microbiota of Rickettsia felis-uninfected and -infected colonized cat fleas, Ctenocephalides felis

Fleas serve as arthropod vectors for several emerging and re-emerging infectious disease causing agents including, Rickettsia felis. Although the prevalence of R. felis infection in colonies of fleas has been examined, the influence of the R. felis infection on flea microbiota has not been investigated. We identified three colonies of cat fleas, Ctenocephalides felis, with varying prevalence of R. felis infection (Louisiana State University (LSU), 93.8; Professional Laboratory and Research Services Inc. (PLRS), 16.4; Elward II (EL), 0) and subsequently utilized polymerase chain reaction amplification, restriction fragment length polymorphism analysis and sequencing of the 1.4-kb portions of 16S rRNA genes to examine the diversity of bacteria in the flea populations. A total of 17 different bacterial 16S rRNA gene sequences were identified among the C. felis colonies. The prevalence of two Wolbachia species that were identified in each flea colony differed between colonies and R. felis-uninfected and -infected fleas. Species richness was unchanged among the R. felis-uninfected (LSU, PLRS and EL colonies) and -infected (LSU and PLRS colonies) fleas; however, between R. felis-uninfected and -infected fleas within both the LSU and PLRS colonies, R. felis-uninfected fleas have greater species richness. Diversity indices did not identify a difference in diversity between any of the flea samples. The interaction of endosymbionts within arthropods can widely impact the dissemination of vertically transmitted pathogenic bacteria; and the reciprocal may be true. These results suggest that carriage of R. felis has an impact on the richness of flea microbiota. © 2007 International Society for Microbial Ecology All rights reserved

Molecular Characterization and Tissue-Specific Gene Expression of Dermacentor variabilis α-catenin in Response to Rickettsial Infection

Alpha catenin is a cytoskeleton protein that acts as a regulator of actin rearrangement by forming an E-cadherin adhesion complex. In Dermacentor variabilis, a putative α-catenin (Dvα-catenin) was previously identified as differentially regulated in ovaries of ticks chronically infected with Rickettsia montanensis. To begin characterizing the role(s) of Dvα-catenin during rickettsial infection, the full-length Dvα-catenin cDNA was cloned and analysed. Comparative sequence analysis demonstrates a 3069-bp cDNA with a 2718-bp open reading frame with a sequence similar to Ixodes scapularis α-catenin. A portion of Dvα-catenin is homologous to the vinculin-conserved domain containing a putative actin-binding region and β-catenin-binding and -dimerization regions. Quantitative reverse-transcription PCR analysis demonstrated that Dvα-catenin is predominantly expressed in tick ovaries and is responsive to tick feeding. The tissue-specific gene expression analysis of ticks exposed to Rickettsia demonstrates that Dvα-catenin expression was significantly downregulated 12 h after exposure to R. montanensis, but not in Rickettsia amblyommii-exposed ovaries, compared with Rickettsia-unexposed ticks. Studying tick-derived molecules associated with rickettsial infection will provide a better understanding of the transmission dynamics of tick-borne rickettsial diseases

Factors associated with profitability in pasture-based systems of milk production

peer-reviewedThe global dairy industry needs to reappraise the systems of milk production that are operated at farm level with specific focus on enhancing technical efficiency and competitiveness of the sector. The objective of this study was to quantify the factors associated with costs of production, profitability, and pasture use, and the effects of pasture use on financial performance of dairy farms using an internationally recognized representative database over an 8-yr period (2008 to 2015) on pasture-based systems. To examine the associated effects of several farm system and management variables on specific performance measures, a series of multiple regression models were developed. Factors evaluated included pasture use [kg of dry matter/ha and stocking rate (livestock units/ha)], grazing season length, breeding season length, milk recording, herd size, dairy farm size (ha), farmer age, discussion group membership, proportion of purchased feed, protein %, fat %, kg of milk fat and protein per cow, kg of milk fat and protein per hectare, and capital investment in machinery, livestock, and buildings. Multiple regression analysis demonstrated costs of production per hectare differed by year, geographical location, soil type, level of pasture use, proportion of purchased feed, protein %, kg of fat and protein per cow, dairy farm size, breeding season length, and capital investment in machinery, livestock, and buildings per cow. The results of the analysis revealed that farm net profit per hectare was associated with pasture use per hectare, year, location, soil type, grazing season length, proportion of purchased feed, protein %, kg of fat and protein per cow, dairy farm size, and capital investment in machinery and buildings per cow. Pasture use per hectare was associated with year, location, soil type, stocking rate, dairy farm size, fat %, protein %, kg of fat and protein per cow, farmer age, capital investment in machinery and buildings per cow, breeding season length, and discussion group membership. On average, over the 8-yr period, each additional tonne of pasture dry matter used increased gross profit by €278 and net profit by €173 on dairy farms. Conversely, a 10% increase in the proportion of purchased feed in the diet resulted in a reduction in net profit per hectare by €97 and net profit by €207 per tonne of fat and protein. Results from this study, albeit in a quota limited environment, have demonstrated that the profitability of pasture-based dairy systems is significantly associated with the proportion of pasture used at the farm level, being cognizant of the levels of purchased feed

A manipulative test of competing theories for metabolic scaling

The reasons why metabolic rate (B) scales allometrically with body mass (M) remain hotly debated. The field is dominated by correlational analyses of the relationship between B and M; these struggle to disentangle competing explanations because both B and M are confounded with ontogeny, life history, and ecology. Here, we overcome these problems by using an experimental approach to test among competing metabolic theories. We examined the scaling of B in size-manipulated and intact colonies of a bryozoan and show that B scales with M. To explain this, we apply a general model based on the dynamic energy budget theory for metabolic organization that predicts B on the basis of energy allocation to assimilation, maintenance, growth, and maturation. Uniquely, this model predicts the absolute value of B, emphasizes that there is no single scaling exponent of B, and demonstrates that a single model can explain the variation in B seen in nature

Effector memory differentiation increases detection of replication-competent HIV-l in resting CD4+ T cells from virally suppressed individuals.

Studies have demonstrated that intensive ART alone is not capable of eradicating HIV-1, as the virus rebounds within a few weeks upon treatment interruption. Viral rebound may be induced from several cellular subsets; however, the majority of proviral DNA has been found in antigen experienced resting CD4+ T cells. To achieve a cure for HIV-1, eradication strategies depend upon both understanding mechanisms that drive HIV-1 persistence as well as sensitive assays to measure the frequency of infected cells after therapeutic interventions. Assays such as the quantitative viral outgrowth assay (QVOA) measure HIV-1 persistence during ART by ex vivo activation of resting CD4+ T cells to induce latency reversal; however, recent studies have shown that only a fraction of replication-competent viruses are inducible by primary mitogen stimulation. Previous studies have shown a correlation between the acquisition of effector memory phenotype and HIV-1 latency reversal in quiescent CD4+ T cell subsets that harbor the reservoir. Here, we apply our mechanistic understanding that differentiation into effector memory CD4+ T cells more effectively promotes HIV-1 latency reversal to significantly improve proviral measurements in the QVOA, termed differentiation QVOA (dQVOA), which reveals a significantly higher frequency of the inducible HIV-1 replication-competent reservoir in resting CD4+ T cells

Cast versus functional brace in the rehabilitation of patients treated non-operatively for a rupture of the Achilles tendon: protocol for the UK study of tendo achilles rehabilitation (UK STAR) multi-centre randomised trial

INTRODUCTION Achilles tendon rupture affects over 11 000 people yearly in the UK, and the incidence is increasing. Controversy remains with regard to the best rehabilitation strategy for these patients. In operatively treated patients, functional bracing provides better outcomes compared with plaster casts. However, the role of functional bracing in non-operatively managed patients is unclear. This is the protocol for a multicentre randomised trial of plaster cast immobilisation versus functional bracing for patients with a non-operatively managed Achilles tendon rupture. METHODS AND ANALYSIS All adults presenting with a primary rupture of the Achilles tendon will be screened. Non-operatively treated patients will be eligible to take part in the trial. Broad eligibility criteria will ensure that the results of the study can be generalised to the wider patient population. Randomisation will be on a 1:1 basis. Both rehabilitation strategies are widely used within the National Health Service. Standardised protocols will be followed, and details of plaster material and brace will be as per the site's usual practice.A minimum of 330 patients will be randomised to obtain 90% power to detect a difference of 8 points in Achilles Tendon Total Rupture Score at 9 months. Quality of life and resource use will be collected at 3, 6 and 9 months. The differences between treatment groups will be assessed on an intention-to-treat basis. The results of the trial-based economic evaluation will be expressed in terms of incremental cost per quality-adjusted life-year gained. ETHICS AND DISSEMINATION The National Research Ethic Committee approved this study on 18 March 2016 (16/SC/0109).The National Institute for Health Research Health Technology Assessment monograph and a manuscript to a peer-reviewed journal will be submitted on completion of the trial (summer 2019). The results of this trial will substantially inform clinical practice on the clinical and cost-effectiveness of the treatment of this injury. This study has been registered on the International Standard Randomised Controlled Trial Number registry with reference no ISRCTN62639639

Color change for Thermoregulation versus camouflage in free-ranging lizards

Animal coloration has multiple functions including thermoregulation,camouflage, and social signaling, and the requirementsof each function may sometimes conflict. Many terrestrial ectothermsaccommodate the multiple functions of color through color change.However, the relative importance of these functions and how colorchangingspecies accommodate themwhen they do conflict are poorlyunderstood because we lack data on color change in the wild. Here, weshow that the color of individual radio-tracked bearded dragon lizards,Pogona vitticeps, correlates strongly with background color andless strongly, but significantly, with temperature. We found no evidencethat individuals simultaneously optimize camouflage and thermoregulationby choosing light backgrounds when hot or dark backgroundswhen cold. In laboratory experiments, lizards showed both UV-visible(300–700 nm) and near-infrared (700–2,100 nm) reflectance changesin response to different background and temperature treatments, consistentwith camouflage and thermoregulatory functions, respectively,but with no interaction between the two. Overall, our results suggestthat wild bearded dragons change color to improve both thermoregulationand camouflage but predominantly adjust for camouflage, suggestingthat compromising camouflage may entail a greater potentialimmediate survival cost