A Cryptic Modifier Causing Transient Self-Incompatibility in Arabidopsis thaliana

SummaryBreakdown of the pollination barrier of self-incompatibility (SI) in older flowers, a phenomenon known as pseudo-self-compatibility or transient SI, has been described as an advantageous reproductive assurance strategy that allows selfing after opportunities for out-crossing have been exhausted [1–9]. Pseudo-self-compatibility is quite prevalent as a mixed mating strategy in nature, but the underlying molecular mechanisms are not known. We had previously shown that Arabidopsis thaliana exhibits cryptic natural variation for pseudo-self-compatibility, which is uncovered by transformation of different accessions with SI specificity-determining SRK and SCR genes from its self-incompatible sister species A. lyrata [10, 11]. Here, by using this transgenic A. thaliana model, we show that pseudo-self-compatibility is caused by a hypomorphic allele of PUB8, an S-locus-linked gene encoding a previously uncharacterized ARM repeat- and U box-containing protein that regulates SRK transcript levels. This is the first gene underlying pseudo-self-compatibility to be identified and the first report in which cryptic natural variation unveiled by a transgene enabled the cloning of a gene for a complex trait

Multicenter prevalence of anaphylaxis in clinic-based oral food challenges

Background Although previous single-center studies report the rate of anaphylaxis for oral food challenges (OFCs) as 9% to 11%, little is known regarding the epidemiology of clinical OFCs across multiple centers in the United States. Objective To examine the epidemiology, symptoms, and treatment of clinical low-risk OFCs in the nonresearch setting. Methods Data were obtained from 2008 to 2013 through a physician survey in 5 food allergy centers geographically distributed across the United States. Allergic reaction rates and the association of reaction rates with year, hospital, and demographics were determined using a linear mixed model. Meta-analysis was used to pool the proportion of reactions and anaphylaxis with inverse-variance weights using a random-effects model with exact confidence intervals (CIs). Results A total of 6,377 OFCs were performed, and the pooled estimate of anaphylaxis was 2% (95% CI, 1%-3%). The rate of allergic reactions was 14% (95% CI, 13%-16%) and was consistent during the study period (P = .40). Reaction rates ranged from 13% to 33%. Males reacted 16% more frequently than females (95% CI, 4%-37.5%; P = .04). Foods challenged in 2013 varied geographically, with peanut as the most challenged food in the Northeast, Midwest, and West and egg as the most challenged in the South. Conclusion As the largest national survey of allergic reactions of clinical open OFCs in a nonresearch setting in the United States, this study found that performing clinical nonresearch open low-risk OFCs results in few allergic reactions, with 86% of challenges resulting in no reactions and 98% without anaphylaxis

Human Rights in the Context of Environmental Conservation on the US-Mexico Border

At Cabeza Priesta National Wildlife Refuge, a wilderness area on the US-Mexico border in Arizona, conflicting policies permit the provision of supplementary water for wildlife but not for undocumented immigrants passing through the area. Federal refuge environmental policy prioritizes active management of endangered and threatened species. Vast systems of water resources have been developed to support wildlife conservation in this extremely hot and dry environment. At the same time, humanitarian groups are not allowed to supply water to undocumented border crossers in the park. Human border-crossers must utilize non-potable wildlife water guzzlers for survival and face risk of illness or death by dehydration. This article analyzes human rights via an ethnographic lens. From this perspective, water policy at the wildlife refuge brings into question the value of human life in a border conservation context, especially for those entering the site illegally

Cardiorespiratory fitness is associated with hard and light intensity physical activity but not time spent sedentary in 10–14 year old schoolchildren: the HAPPY study

Sedentary behaviour is a major risk factor for developing chronic diseases and is associated with low cardiorespiratory fitness in adults. It remains unclear how sedentary behaviour and different physical activity subcomponents are related to cardiorespiratory fitness in children. The purpose of this study was to assess how sedentary behaviour and different physical activity subcomponents are associated with 10–14 year-old schoolchildren's cardiorespiratory fitness

Trajectories for the Wave Function of the Universe from a Simple Detector Model

Inspired by Mott's (1929) analysis of particle tracks in a cloud chamber, we consider a simple model for quantum cosmology which includes, in the total Hamiltonian, model detectors registering whether or not the system, at any stage in its entire history, passes through a series of regions in configuration space. We thus derive a variety of well-defined formulas for the probabilities for trajectories associated with the solutions to the Wheeler-DeWitt equation. The probability distribution is peaked about classical trajectories in configuration space. The ``measured'' wave functions still satisfy the Wheeler-DeWitt equation, except for small corrections due to the disturbance of the measuring device. With modified boundary conditions, the measurement amplitudes essentially agree with an earlier result of Hartle derived on rather different grounds. In the special case where the system is a collection of harmonic oscillators, the interpretation of the results is aided by the introduction of ``timeless'' coherent states -- eigenstates of the Hamiltonian which are concentrated about entire classical trajectories.Comment: 37 pages, plain Tex. Second draft. Substantial revision

Expression and trans-specific polymorphism of self-incompatibility RNases in Coffea (Rubiaceae)

Self-incompatibility (SI) is widespread in the angiosperms, but identifying the biochemical components of SI mechanisms has proven to be difficult in most lineages. Coffea (coffee; Rubiaceae) is a genus of old-world tropical understory trees in which the vast majority of diploid species utilize a mechanism of gametophytic self-incompatibility (GSI). The S-RNase GSI system was one of the first SI mechanisms to be biochemically characterized, and likely represents the ancestral Eudicot condition as evidenced by its functional characterization in both asterid (Solanaceae, Plantaginaceae) and rosid (Rosaceae) lineages. The S-RNase GSI mechanism employs the activity of class III RNase T2 proteins to terminate the growth of "self" pollen tubes. Here, we investigate the mechanism of Coffea GSI and specifically examine the potential for homology to S-RNase GSI by sequencing class III RNase T2 genes in populations of 14 African and Madagascan Coffea species and the closely related self-compatible species Psilanthus ebracteolatus. Phylogenetic analyses of these sequences aligned to a diverse sample of plant RNase T2 genes show that the Coffea genome contains at least three class III RNase T2 genes. Patterns of tissue-specific gene expression identify one of these RNase T2 genes as the putative Coffea S-RNase gene. We show that populations of SI Coffea are remarkably polymorphic for putative S-RNase alleles, and exhibit a persistent pattern of trans-specific polymorphism characteristic of all S-RNase genes previously isolated from GSI Eudicot lineages. We thus conclude that Coffea GSI is most likely homologous to the classic Eudicot S-RNase system, which was retained since the divergence of the Rubiaceae lineage from an ancient SI Eudicot ancestor, nearly 90 million years ago.United States National Science Foundation [0849186]; Society of Systematic Biologists; American Society of Plant Taxonomists; Duke University Graduate Schoolinfo:eu-repo/semantics/publishedVersio

Time-dependent bending rigidity and helical twist of DNA by rearrangement of bound HU protein

HU is a protein that plays a role in various bacterial processes including compaction, transcription and replication of the genome. Here, we use atomic force microscopy to study the effect of HU on the stiffness and supercoiling of double-stranded DNA. First, we measured the persistence length, height profile, contour length and bending angle distribution of the DNA–HU complex after different incubation times of HU with linear DNA. We found that the persistence and contour length depend on the incubation time. At high concentrations of HU, DNA molecules first become stiff with a larger value of the persistence length. The persistence length then decreases over time and the molecules regain the flexibility of bare DNA after ~2 h. Concurrently, the contour length shows a slight increase. Second, we measured the change in topology of closed circular relaxed DNA following binding of HU. Here, we observed that HU induces supercoiling over a similar time span as the measured change in persistence length. Our observations can be rationalized in terms of the formation of a nucleoprotein filament followed by a structural rearrangement of the bound HU on DNA. The rearrangement results in a change in topology, an increase in bending flexibility and an increase in contour length through a decrease in helical pitch of the duplex.Singapore-MIT Alliance for Research and Technolog

Harmonising data on the correlates of physical activity and sedentary behaviour in young people: Methods and lessons learnt from the international Children's Accelerometry database (ICAD).

BACKGROUND: Large, heterogeneous datasets are required to enhance understanding of the multi-level influences on children's physical activity and sedentary behaviour. One route to achieving this is through the pooling and co-analysis of data from multiple studies. Where this approach is used, transparency of the methodology for data collation and harmonisation is essential to enable appropriate analysis and interpretation of the derived data. In this paper, we describe the acquisition, management and harmonisation of non-accelerometer data in a project to expand the International Children's Accelerometry Database (ICAD). METHOD: Following a consultation process, ICAD partners were requested to share accelerometer data and information on selected behavioural, social, environmental and health-related constructs. All data were collated into a single repository for cataloguing and harmonisation. Harmonised variables were derived iteratively, with input from the ICAD investigators and a panel of invited experts. Extensive documentation, describing the source data and harmonisation procedure, was prepared and made available through the ICAD website. RESULTS: Work to expand ICAD has increased the number of studies with longitudinal accelerometer data, and expanded the breadth of behavioural, social and environmental characteristics that can be used as exposure variables. A set of core harmonised variables, including parent education, ethnicity, school travel mode/duration and car ownership, were derived for use by the research community. Guidance documents and facilities to enable the creation of new harmonised variables were also devised and made available to ICAD users. An expanded ICAD database was made available in May 2017. CONCLUSION: The project to expand ICAD further demonstrates the feasibility of pooling data on physical activity, sedentary behaviour and potential determinants from multiple studies. Key to this process is the rigorous conduct and reporting of retrospective data harmonisation, which is essential to the appropriate analysis and interpretation of derived data. These documents, made available through the ICAD website, may also serve as a guide to others undertaking similar projects