Showing papers by "University of Oregon published in 2004"
TL;DR: For instance, this article argued that analytic reasoning cannot be effective unless it is guided by emotion and affect, and argued that rational decision making requires proper integration of both modes of thought.
Abstract: Modern theories in cognitive psychology and neuroscience indicate that there are two fundamental ways in which human beings comprehend risk. The “analytic system” uses algorithms and normative rules, such as probability calculus, formal logic, and risk assessment. It is relatively slow, effortful, and requires conscious control. The “experiential system” is intuitive, fast, mostly automatic, and not very accessible to conscious awareness. The experiential system enabled human beings to survive during their long period of evolution and remains today the most natural and most common way to respond to risk. It relies on images and associations, linked by experience to emotion and affect (a feeling that something is good or bad). This system represents risk as a feeling that tells us whether it is safe to walk down this dark street or drink this strange-smelling water. Proponents of formal risk analysis tend to view affective responses to risk as irrational. Current wisdom disputes this view. The rational and the experiential systems operate in parallel and each seems to depend on the other for guidance. Studies have demonstrated that analytic reasoning cannot be effective unless it is guided by emotion and affect. Rational decision making requires proper integration of both modes of thought. Both systems have their advantages, biases, and limitations. Now that we are beginning to understand the complex interplay between emotion and reason that is essential to rational behavior, the challenge before us is to think creatively about what this means for managing risk. On the one hand, how do we apply reason to temper the strong emotions engendered by some risk events? On the other hand, how do we infuse needed “doses of feeling” into circumstances where lack of experience may otherwise leave us too “coldly rational”? This article addresses these important questions.
2,847 citations
TL;DR: The Patient Activation Measure is a valid, highly reliable, unidimensional, probabilistic Guttman-like scale that reflects a developmental model of activation that has good psychometric properties indicating that it can be used at the individual patient level to tailor intervention and assess changes.
Abstract: Two significant emerging policy directions put patients and consumers in a key role for influencing health care quality and costs. First, consumer-directed health plans rely on informed consumer choices to contain costs and improve the quality of care. This approach assumes that consumers will make more prudent health and health care choices when they are given financial incentives along with access to comparative cost and quality information. This approach also assumes that the combination of financial incentives and relevant information will increase their “activation” (Gabel, Lo Sasso, and Rice 2002). Second, the Chronic Illness Care Model (Bodenheimer et al. 2002) emphasizes patient-oriented care, with patients and their families integrated as members of the care team. A critical element in the model is activated patients, with the skills, knowledge, and motivation to participate as effective members of the care team (Von Korff et al. 1997).
A key health policy question is, what would it take for consumers to become effective and informed managers of their health and health care? What skills, knowledge, beliefs, and motivations do they need to become “activated” or more effectual health care actors? These are essential questions if we hope to improve the health care process, the outcomes of care, and control costs. This is true especially with regard to the 99 million Americans with a chronic disease. Because those with chronic illness need ongoing care, account for a large portion of health care costs, and must play an important role in maintaining their own functioning, encouraging their activation should be a priority.
Even though patient activation is a central concept in both the consumer driven health care approach and the chronic illness care models, it remains conceptually and empirically underdeveloped. There has been a lack of conceptual clarity regarding “activation,” and thus a lack of adequate measurement. There are a number of existing methods for assessing different aspects of activation, such as health locus of control (Wallston, Stein, and Smith), self-efficacy in self-managing behaviors (Lorig et al. 1996), and readiness to change health-related behaviors (DiClemente et al. 1991; Prochaska, Redding, and Evers 1997), but these measures tend to focus on the prediction of a single behavior. Moreover, there is no existing measure that includes the broad range of elements involved in activation, including the knowledge, skills, beliefs, and behaviors that a patient needs to manage a chronic illness.
In this paper we describe the development of the Patient Activation Measure (PAM), a measure of activation that is grounded in rigorous conceptualization and appropriate psychometric methods. The PAM was developed in four stages:
Stage 1.Conceptually defining activation involved a literature review, systematic consultation with experts using a “consensus method,” and consultation with individuals with chronic disease using focus groups.
Stage 2.Preliminary scale development began by building on the domains identified in stage one and operationalizing them with survey items within each domain. Steps included generating, refining, and testing a large item pool. We used Rasch psychometric methods to develop the scale and test the preliminary measure's psychometric properties.
Stage 3.Stage three involved exploring the possibility of extending the range of the measure, refining the response categories, and testing whether the measure could be used with respondents who had no chronic illnesses.
Stage 4.In the fourth and final stage a national probability sample was used to assess the performance of the measure across different subsamples in the population and to assess the construct validity of the measure.
2,085 citations
TL;DR: In this article, the authors present conditions under which community participation may be costly and ineffective and when it can thrive and produce the greatest gains in effective citizen governance, motivated by contextual problems encountered in a participatory watershed management initiative.
Abstract: It is widely argued that increased community participation in government decision making produces many important benefits. Dissent is rare: It is difficult to envision anything but positive outcomes from citizens joining the policy process, collaborating with others and reaching consensus to bring about positive social and environmental change. This article, motivated by contextual problems encountered in a participatory watershed management initiative, reviews the citizen-participation literature and analyzes key considerations in determining whether community participation is an effective policy-making tool. We list conditions under which community participation may be costly and ineffective and when it can thrive and produce the greatest gains in effective citizen governance. From the detritus of an unsuccessful citizen-participation effort, we arrive at a more informed approach to guide policy makers in choosing a decision-making process that is appropriate for a community's particular needs.
1,714 citations
TL;DR: This work provides electrophysiological evidence for lateralized activity in humans that reflects the encoding and maintenance of items in visual memory and provides a strong neurophysiological predictor of an individual's capacity, allowing a direct relationship between neural activity and memory capacity.
Abstract: Contrary to our rich phenomenological visual experience, our visual short-term memory system can maintain representations of only three to four objects at any given moment. For over a century, the capacity of visual memory has been shown to vary substantially across individuals, ranging from 1.5 to about 5 objects. Although numerous studies have recently begun to characterize the neural substrates of visual memory processes, a neurophysiological index of storage capacity limitations has not yet been established. Here, we provide electrophysiological evidence for lateralized activity in humans that reflects the encoding and maintenance of items in visual memory. The amplitude of this activity is strongly modulated by the number of objects being held in the memory at the time, but approaches a limit asymptotically for arrays that meet or exceed storage capacity. Indeed, the precise limit is determined by each individual's memory capacity, such that the activity from low-capacity individuals reaches this plateau much sooner than that from high-capacity individuals. Consequently, this measure provides a strong neurophysiological predictor of an individual's capacity, allowing the demonstration of a direct relationship between neural activity and memory capacity.
1,656 citations
TL;DR: In this paper, the authors make specific suggestions for conceptualizing and defining creativity to maximize its potential contributions to educational psychology, and make use of the fact that creativity appears to be an important component of problem-solving and other cognitive abilities, healthy social and emotional well-being.
Abstract: The construct of creativity has a great deal to offer educational psychology. Creativity appears to be an important component of problem-solving and other cognitive abilities, healthy social and emotional well-being, and scholastic and adult success. Yet the study of creativity is not nearly as robust as one would expect, due in part to the preponderance of myths and stereotypes about creativity that collectively strangle most research efforts in this area. The root cause of these stereotypes is the lack of adequate precision in the definition of creativity. The body of the article is devoted to specific suggestions for conceptualizing and defining creativity to maximize its potential contributions to educational psychology.
1,283 citations
TL;DR: An integrated Attention Network Test (ANT) to measure the efficiency of the three networks with adults was adapted to study the development of these networks during childhood and suggested that children like adults showed independence between theThree networks under some conditions.
1,199 citations
TL;DR: Functional magnetic resonance imaging is used to identify the neural systems involved in keeping unwanted memories out of awareness and establish a neurobiological model for guiding inquiry into motivated forgetting.
Abstract: Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.
952 citations
TL;DR: By substitution of surface-exposed residues on the Aequorea victoria green fluorescent protein with cysteines in appropriate positions to form disulfide bonds, reduction-oxidation-sensitive GFPs (roGFPs) have been created and targeted to the mitochondria in HeLa cells.
916 citations
Northern Arizona University1, United States Geological Survey2, Loughborough University3, University of Washington4, University of Colorado Boulder5, University of Oregon6, University of New Brunswick7, Bates College8, Geological Survey of Canada9, Norwegian University of Science and Technology10, University of Cincinnati11, University of Ottawa12, University of Iceland13, University of Illinois at Urbana–Champaign14, University of Edinburgh15, University of Denver16, University of California, Los Angeles17, University of South Carolina18, National Center for Atmospheric Research19, California State University, Long Beach20, Queen's University21, Wilfrid Laurier University22
TL;DR: In this paper, a spatio-temporal pattern of peak Holocene warmth (Holocene thermal maximum, HTM) is traced over 140 sites across the Western Hemisphere of the Arctic (0−180°W; north of ∼60°N).
838 citations
TL;DR: The data show that the defective mitochondrial system described in cancer cells can be dramatically improved by solely changing substrate availability and that HeLa cells can adapt their mitochondrial network structurally and functionally to derive energy by glutaminolysis only.
Abstract: Comparative analysis of cytoplasmic organelles in a variety of tumors relative to normal tissues generally reveals a strong diminution in mitochondrial content and in oxidative phosphorylation capacity. However, little is known about what triggers these modifications and whether or not they are physiologically reversible. We hypothesized that energy substrate availability could play an important role in this phenomenon. The physiological effects of a change in substrate availability were examined on a human cancer cell line (HeLa), focusing specifically on its ability to use glycolysis versus oxidative phosphorylation, and the effect that energy substrate type has on mitochondrial composition, structure, and function. Changes in oxidative phosphorylation were measured in vivo by a variety of techniques, including the use of two novel ratiometric green fluorescent protein biosensors, the expression level of oxidative phosphorylation and some glycolytic enzymes were determined by Western blot, mitochondrial DNA content was measured by real-time PCR, and mitochondrial morphology was monitored by both confocal and electron microscopy. Our data show that the defective mitochondrial system described in cancer cells can be dramatically improved by solely changing substrate availability and that HeLa cells can adapt their mitochondrial network structurally and functionally to derive energy by glutaminolysis only. This could also provide an explanation for the enhancement of oxidative phosphorylation capacity observed after tumor regression or removal. Our work demonstrates that the pleomorphic, highly dynamic structure of the mitochondrion can be remodeled to accommodate a change in oxidative phosphorylation activity. We compared our finding on HeLa cells with those for nontransformed fibroblasts to help distinguish the regulatory pathways.
782 citations
TL;DR: The response of the redox probes under physiological redox changes during superoxide bursts in macrophage cells, hyperoxic and hypoxic conditions, and in responses to H2O2-stimulating agents, e.g. epidermal growth factor and lysophosphatidic acid is investigated.
University of California, Riverside1, California State Polytechnic University, Pomona2, Hebrew University of Jerusalem3, University of Oregon4, University of California, Los Angeles5, University of Edinburgh6, University of Göttingen7, Wright State University8, University of Minnesota9, University of Missouri–Kansas City10, Bio-Rad Laboratories11, University of Düsseldorf12, Technische Universität München13, University of Alberta14, University of Leeds15, Massachusetts Institute of Technology16, Dartmouth College17, Flinders University18, Saitama University19, Oregon Health & Science University20, Ohio State University21, University of California, Irvine22, Texas A&M University23, Anschutz Medical Campus24
TL;DR: An analysis of over 1,100 of the ∼10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa reveals potential new targets for antifungals as well as loci implicated in human and plant physiology and disease.
Abstract: We present an analysis of over 1,100 of the approximately 10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa. Seven major areas of Neurospora genomics and biology are covered. First, the basic features of the genome, including the automated assembly, gene calls, and global gene analyses are summarized. The second section covers components of the centromere and kinetochore complexes, chromatin assembly and modification, and transcription and translation initiation factors. The third area discusses genome defense mechanisms, including repeat induced point mutation, quelling and meiotic silencing, and DNA repair and recombination. In the fourth section, topics relevant to metabolism and transport include extracellular digestion; membrane transporters; aspects of carbon, sulfur, nitrogen, and lipid metabolism; the mitochondrion and energy metabolism; the proteasome; and protein glycosylation, secretion, and endocytosis. Environmental sensing is the focus of the fifth section with a treatment of two-component systems; GTP-binding proteins; mitogen-activated protein, p21-activated, and germinal center kinases; calcium signaling; protein phosphatases; photobiology; circadian rhythms; and heat shock and stress responses. The sixth area of analysis is growth and development; it encompasses cell wall synthesis, proteins important for hyphal polarity, cytoskeletal components, the cyclin/cyclin-dependent kinase machinery, macroconidiation, meiosis, and the sexual cycle. The seventh section covers topics relevant to animal and plant pathogenesis and human disease. The results demonstrate that a large proportion of Neurospora genes do not have homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The group of unshared genes includes potential new targets for antifungals as well as loci implicated in human and plant physiology and disease.
TL;DR: In this paper, school districts throughout the country are encouraged to implement school-wide positive behavior support (PBS) procedures as a way to improve their behavioral climate, safety, and social culture.
Abstract: Schools throughout the country are now encouraged to implement school-wide positive behavior support (PBS) procedures as a way to improve their behavioral climate, safety, and social culture. Resea...
TL;DR: The ASTRAL Compendium provides several databases and tools to aid in the analysis of protein structures, particularly through the use of their sequences, and all SCOP domains are now made available as PDB-style coordinate files as well as sequences.
Abstract: The ASTRAL Compendium provides several databases and tools to aid in the analysis of protein structures, particularly through the use of their sequences. Partially derived from the SCOP database of protein structure domains, it includes sequences for each domain and other resources useful for studying these sequences and domain structures. The current release of ASTRAL contains 54,745 domains, more than three times as many as the initial release 4 years ago. ASTRAL has undergone major transformations in the past 2 years. In addition to several complete updates each year, ASTRAL is now updated on a weekly basis with preliminary classifications of domains from newly released PDB structures. These classifications are available as a stand-alone database, as well as integrated into other ASTRAL databases such as representative subsets. To enhance the utility of ASTRAL to structural biologists, all SCOP domains are now made available as PDB-style coordinate files as well as sequences. In addition to sequences and representative subsets based on SCOP domains, sequences and subsets based on PDB chains are newly included in ASTRAL. Several search tools have been added to ASTRAL to facilitate retrieval of data by individual users and automated methods. ASTRAL may be accessed at http://astral.stanford. edu/.
TL;DR: It is shown that maximum likelihood and BMCMC can become strongly biased and statistically inconsistent when the rates at which sequence sites evolve change non-identically over time.
Abstract: All inferences in comparative biology depend on accurate estimates of evolutionary relationships. Recent phylogenetic analyses have turned away from maximum parsimony towards the probabilistic techniques of maximum likelihood and bayesian Markov chain Monte Carlo (BMCMC). These probabilistic techniques represent a parametric approach to statistical phylogenetics, because their criterion for evaluating a topology--the probability of the data, given the tree--is calculated with reference to an explicit evolutionary model from which the data are assumed to be identically distributed. Maximum parsimony can be considered nonparametric, because trees are evaluated on the basis of a general metric--the minimum number of character state changes required to generate the data on a given tree--without assuming a specific distribution. The shift to parametric methods was spurred, in large part, by studies showing that although both approaches perform well most of the time, maximum parsimony is strongly biased towards recovering an incorrect tree under certain combinations of branch lengths, whereas maximum likelihood is not. All these evaluations simulated sequences by a largely homogeneous evolutionary process in which data are identically distributed. There is ample evidence, however, that real-world gene sequences evolve heterogeneously and are not identically distributed. Here we show that maximum likelihood and BMCMC can become strongly biased and statistically inconsistent when the rates at which sequence sites evolve change non-identically over time. Maximum parsimony performs substantially better than current parametric methods over a wide range of conditions tested, including moderate heterogeneity and phylogenetic problems not normally considered difficult.
TL;DR: In this article, a review of the late Quaternary vegetation history in northern and eastern North America across levels of ecological organization from individual taxa to biomes, and apply the insights gained from this review to critically examine the biome maps generated from the pollen data.
Abstract: This paper integrates recent efforts to map the distribution of biomes for the late Quaternary with the detailed evidence that plant species have responded individual- istically to climate change at millennial timescales. Using a fossil-pollen data set of over 700 sites, we review late-Quaternary vegetation history in northern and eastern North America across levels of ecological organization from individual taxa to biomes, and apply the insights gained from this review to critically examine the biome maps generated from the pollen data. Higher-order features of the vegetation (e.g., plant associations, physiog- nomy) emerge from individualistic responses of plant taxa to climate change, and different representations of vegetation history reveal different aspects of vegetation dynamics. Veg- etation distribution and composition were relatively stable during full-glacial times (21 000- 17 000 yr BP) (calendar years) and during the mid- to late Holocene (7000-500 yr BP), but changed rapidly during the late-glacial period and early Holocene (16 000-8 000 yr BP) and after 500 yr BP. Shifts in plant taxon distributions were characterized by individ- ualistic changes in population abundances and ranges and included large east-west shifts in distribution in addition to the northward redistribution of most taxa. Modern associations such as Fagus-Tsuga and Picea-Alnus-Betula date to the early Holocene, whereas other associations common to the late-glacial period (e.g., Picea-Cyperaceae-Fraxinus-Ostrya/ Carpinus) no longer exist. Biomes are dynamic entities that have changed in distribution, composition, and structure over time. The late-Pleistocene suite of biomes is distinct from those that grew during the Holocene. The pollen-based biome reconstructions are able to capture the major features of late-Quaternary vegetation but downplay the magnitude and variety of vegetational responses to climate change by (1) limiting apparent land-cover change to ecotones, (2) masking internal variations in biome composition, and (3) obscuring the range shifts and changes in abundance among individual taxa. The compositional and structural differences between full-glacial and recent biomes of the same type are similar to or greater than the spatial heterogeneity in the composition and structure of present-day biomes. This spatial and temporal heterogeneity allows biome maps to accommodate in- dividualistic behavior among species but masks climatically important variations in taxo- nomic composition as well as structural differences between modern biomes and their ancient counterparts.
TL;DR: The authors argue that focus group discussions are shaped by multiple social contexts, such as associational, status (especially gender), conversational, and relational contexts, and they make focus groups an excellent site for analyzing the processes of social interaction.
Abstract: This article argues that focus group discussions are shaped by multiple social contexts, a fact that is often ignored by researchers. Using data from a focus group study of the effects of violence on everyday life, this article provides an analysis of four such contexts: the associational, status (especially gender), conversational, and relational contexts. These multiple and overlapping contexts foster both problematic silences (lack of disclosure) and problematic speech (strategic shaping of comments) in group discussions. These processes limit the usefulness of focus groups as a tool for understanding individual thoughts, feelings, or experiences. However, they make focus groups an excellent site for analyzing the processes of social interaction. The article concludes with suggestions for improving the implementation and interpretation of focus groups in light of this analysis.
TL;DR: These results appear consistent with a body of research that demonstrates a relationship between limbic theta activity and action regulation, including error monitoring and learning.
TL;DR: Examination of the relative contributions of two aspects of executive function-inhibitory control and planning ability-to theory of mind in 49 3- and 4-year-olds indicated that two inhibition tasks were significantly related to theory ofMind after accounting for age, receptive vocabulary, and planning.
TL;DR: In this paper, the authors constructed accurate, high-resolution DEMs from airborne laser altimetry (LIDAR) data to characterize a large landslide complex and surrounding terrain near Christchurch, New Zealand.
TL;DR: The field of work motivation has received much attention over the past several decades in both research journals and management periodicals as mentioned in this paper, and it is not surprising, therefore, that this topic has received so much attention.
Abstract: The topic of employee motivation plays a cen tral role in the field of management?both prac tically and theoretically. Managers see motiva tion as an integral part of the performance equation at all levels, while organizational re searchers see it as a fundamental building block in the development of useful theories of effective management practice. Indeed, the topic of motivation permeates many of the sub fields that compose the study of management, including leadership, teams, performance man agement, managerial ethics, decision making, and organizational change. It is not surprising, therefore, that this topic has received so much attention over the past several decades in both research journals and management periodicals. Whereas several recent articles have exam ined how far we have come in researching work motivation, this special forum focuses on where we are going.1 That is, we ask the questions: What is the future of work motivation theories? What are the critical questions that must be addressed if progress in the field is to be made? What is the future research agenda? How can we extend or modify current models of work motivation so they continue to be relevant in the future? And where are entirely new models of motivation needed to further our understanding of employee behavior and job performance in contemporary organizations? To understand where the field is going, how ever, we must first understand where it has been. This introduction represents an overview of the field of work motivation from a theoretical
TL;DR: The authors used the theories of Weber and Bourdieu to advance an alternative view of departmental prestige, which is an effect a department's position within networks of association and social exchange, that is, it is a form of social capital.
Abstract: The prestige of academic departments is commonly understood as rooted in the scholarly productivity of their faculty and graduates. I use the theories of Weber and Bourdieu to advance an alternative view of departmental prestige, which I show is an effect a department's position within networks of association and social exchange—that is, it is a form of social capital. The social network created by the exchange of PhDs among departments is the most important network of this kind. Using data on the exchange of PhDs among sociology departments, I apply network analysis to investigate this alternative conception of departmental prestige and to demonstrate its superiority over the conventional view. Within sociology, centrality within interdepartmental hiring networks explains 84 percent of the variance in departmental prestige. Similar findings are reported for history and political science. This alternative understanding of academic prestige helps clarify anomalies—e.g., the variance in prestige unconnected...
TL;DR: This paper considers the possibility that persistent poverty may arise from a high incidence of mortality, which is introduced in a two-period overlapping generations model and depends upon health capital that can be augmented through public investment.
TL;DR: Loss of ventricular muscle cell lineage specification into trabecular and conduction system myocytes is a new mechanistic pathway for progressive cardiomyopathy and Conduction defects in congenital heart disease.
TL;DR: Evidence is examined for an ancient whole-genome duplication (tetraploidization) event that probably occurred just before the teleost radiation, which could have contributed to the genetic isolation of populations, to lineage-specific diversification of developmental programs, and ultimately to phenotypic variation among teleost fish.
TL;DR: In predicting late adolescent problem behaviour, there was a statistically reliable interaction between family management degradation and deviant peer involvement in adolescence in support of the premature autonomy hypothesis.
TL;DR: The analysis of the N. crassa genome sequence reveals a complete absence of intact mobile elements and reveals that RIP has impacted genome evolution significantly through gene duplication, which is considered to be crucial for the evolution of new functions.
University of Wyoming1, University of Oregon2, Oak Ridge National Laboratory3, Northern Arizona University4, Marine Biological Laboratory5, University of Nevada, Reno6, Oregon State University7, University of Oklahoma8, Smithsonian Environmental Research Center9, Lund University10, Colorado State University11
TL;DR: In this article, the current status of below-ground responses to elevated CO2 and temperature and potential feedback effects, methodological challenges, and approaches to integrating models and measurements are discussed, as well as approaches to integrate models and data to predict long-term, net carbon storage in ecosystems.
Abstract: Rising atmospheric CO2 and temperatures are probably altering ecosystem carbon cycling, causing both positive and negative feedbacks to climate. Below-ground processes play a key role in the global carbon (C) cycle because they regulate storage of large quantities of C, and are potentially very sensitive to direct and indirect effects of elevated CO2 and temperature. Soil organic matter pools, roots and associated rhizosphere organisms all have distinct responses to environmental change drivers, although availability of C substrates will regulate all the responses. Elevated CO2 increases C supply below-ground, whereas warming is likely to increase respiration and decomposition rates, leading to speculation that these effects will moderate one another. However, indirect effects on soil moisture availability and nutrient supply may alter processes in unexpected directions. Detailed, mechanistic understanding and modelling of below-ground flux components, pool sizes and turnover rates is needed to adequately predict long-term, net C storage in ecosystems. In this synthesis, we discuss the current status of below-ground responses to elevated CO2 and temperature and potential feedback effects, methodological challenges, and approaches to integrating models and measurements.
TL;DR: An inverse distribution of two sequentially acting miRNAs in two bilaterally symmetric neurons controls laterality of the nematode chemosensory system.
Abstract: Animal microRNAs (miRNAs) are gene regulatory factors that prevent the expression of specific messenger RNA targets by binding to their 3' untranslated region. The Caenorhabditis elegans lsy-6 miRNA (for lateral symmetry defective) is required for the left/right asymmetric expression of guanyl cyclase (gcy) genes in two chemosensory neurons termed ASE left (ASEL) and ASE right (ASER). The asymmetric expression of these putative chemoreceptors in turn correlates with the functional lateralization of the ASE neurons. Here we find that a mutation in the die-1 zinc-finger transcription factor disrupts both the chemosensory laterality and left/right asymmetric expression of chemoreceptor genes in the ASE neurons. die-1 controls chemosensory laterality by activating the expression of lsy-6 specifically in ASEL, but not in ASER, where die-1 expression is downregulated through two sites in its 3' untranslated region. These two sites are complementary to mir-273, a previously uncharacterized miRNA, whose expression is strongly biased towards ASER. Forced bilateral expression of mir-273 in ASEL and ASER causes a loss of asymmetric die-1 expression and ASE laterality. Thus, an inverse distribution of two sequentially acting miRNAs in two bilaterally symmetric neurons controls laterality of the nematode chemosensory system.
TL;DR: Rapid and repeated armor loss in Alaskan stickleback populations appears to be occurring through the fixation of large-effect variants in the same genes, implicating the same Mendelian armor reduction genes.
Abstract: Most adaptation is thought to occur through the fixation of numerous alleles at many different loci. Consequently, the independent evolution of similar phenotypes is predicted to occur through different genetic mechanisms. The genetic basis of adaptation is still largely unknown, however, and it is unclear whether adaptation to new environments utilizes ubiquitous small-effect polygenic variation or large-effect alleles at a small number of loci. To address this question, we examined the genetic basis of bony armor loss in three freshwater populations of Alaskan threespine stickleback, Gasterosteus aculeatus, that evolved from fully armored anadromous populations in the last 14,000 years. Crosses between complete-armor and low-armor populations revealed that a single Mendelian factor governed the formation of all but the most anterior lateral plates, and another independently segregating factor largely determined pelvic armor. Genetic mapping localized the Mendelian genes to different chromosomal regions, and crosses among these same three widely separated populations showed that both bony plates and pelvic armor failed to fully complement, implicating the same Mendelian armor reduction genes. Thus, rapid and repeated armor loss in Alaskan stickleback populations appears to be occurring through the fixation of large-effect variants in the same genes.