70 research outputs found
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Investigating complex larval traits in a reef-building coral
Dispersal of the majority of large benthic marine invertebrates relies on a planktonic phase of the life cycle dispersed by ocean currents. Patterns and spatial scales of larval dispersal drive biogeographic distributions, genetic connectivity and population and community dynamics. Biological parameters that drive dispersal potential include larval traits such as the onset and length of competence, the ability of larvae to metamorphose in response to a specific environmental cue, and the rate of energetic storage depletion. This dissertation examines complex larval traits of a reef-building coral, Acropora millepora, giving insight into how larval trait variation and molecular pathways may contribute to the propensity to disperse. First, I examined whether or not light color (wavelength) acts as a cue to influence the likelihood of settlement and metamorphosis in two species of reef-building coral. I found that exposure to different colored lights impacts the propensity to metamorphose when exposed to chemical settlement cues, and these differences in behavior reflect wavelengths of light roughly associated with their respective habitats. Second, I characterized gene expression differences between three larval fluorescent color morphs in order to elucidate the functional significance of color variation in larvae. I found that red fluorescent larvae have gene expression profiles that correlate with gene expression profiles associated with coral larval thermal tolerance and diapause in other organisms. This suggests that red fluorescent larvae may be physiologically able to exist in the water column longer, potentially dispersing longer distances. Third, I described patterns of gene expression through development and correlated these patterns to competence and fluorescence. This revealed that larval maturation associated with competence is correlated with gene expression of neuropeptide signaling, ion transport and GPCR signaling. Environmental perturbation, such as temperature, may affect these pathways, which could alter larval dispersal dynamics in the sea. Finally, to complement these correlative studies, I developed the first method of genomic manipulation in reef-building corals. Utilizing the CRISPR/Cas9 system induced targeted mutagenesis in candidate genes associated with larval dispersal traits. This work is foundational to study gene functions in an ecological context, which will greatly improve our understanding of coral biology.Ecology, Evolution and Behavio
Effects of Thermal Stress on Amount, Composition, and Antibacterial Properties of Coral Mucus
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, United States of America ABSTRACT The surface mucus layer of reef-building corals supports feeding, sediment clearing, and protection from pathogenic invaders. As much as half of the fixed carbon supplied by the corals\u27 photosynthetic symbionts is incorporated into expelled mucus. It is therefore reasonable to expect that coral bleaching (disruption of the coralfialgal symbiosis) would affect mucus production. Since coral mucus serves as an important nutrient source for the entire reef community, this could have substantial ecosystemwide consequences. In this study, we examined the effects of heat stress-induced coral bleaching on the composition and antibacterial properties of coral mucus. In a controlled laboratory thermal challenge, stressed corals produced mucus with higher protein (D 2:1, p \u3c 0:001) and lipid content (D 15:7, p D 0:02) and increased antibacterial activity (likelihood ratio D 100, p \u3c 0:001) relative to clonal controls. These results are likely explained by the expelled symbionts in the mucus of bleached individuals. Our study suggests that coral bleaching could immediately impact the nutrient flux in the coral reef ecosystem via its effect on coral mucus
Relationship between Acropora millepora juvenile fluorescence and composition of newly established Symbiodinium assemblage
Coral-dinoflagellate symbiosis is the key biological interaction enabling existence of modern-type coral reefs, but the mechanisms regulating initial hostâsymbiont attraction, recognition and symbiont proliferation thus far remain largely unclear. A common reef-building coral, Acropora millepora, displays conspicuous fluorescent polymorphism during all phases of its life cycle, due to the differential expression of fluorescent proteins (FPs) of the green fluorescent protein family. In this study, we examine whether fluorescent variation in young coral juveniles exposed to natural sediments is associated with the uptake of disparate Symbiodinium assemblages determined using ITS-2 deep sequencing. We found that Symbiodinium assemblages varied significantly when redness values varied, specifically in regards to abundances of clades A and C. Whether fluorescence was quantified as a categorical or continuous trait, clade A was found at higher abundances in redder juveniles. These preliminary results suggest juvenile fluorescence may be associated with Symbiodinium uptake, potentially acting as either an attractant to ecologically specific types or as a mechanism to modulate the internal light environment to control Symbiodinium physiology within the host
Effects of thermal stress on amount, composition, and antibacterial properties of coral mucus
The surface mucus layer of reef-building corals supports feeding, sediment clearing, and protection from pathogenic invaders. As much as half of the fixed carbon supplied by the coralsâ photosynthetic symbionts is incorporated into expelled mucus. It is therefore reasonable to expect that coral bleaching (disruption of the coralâalgal symbiosis) would affect mucus production. Since coral mucus serves as an important nutrient source for the entire reef community, this could have substantial ecosystem-wide consequences. In this study, we examined the effects of heat stress-induced coral bleaching on the composition and antibacterial properties of coral mucus. In a controlled laboratory thermal challenge, stressed corals produced mucus with higher protein (ÎČ = 2.1, p < 0.001) and lipid content (ÎČ = 15.7, p = 0.02) and increased antibacterial activity (likelihood ratio = 100, p < 0.001) relative to clonal controls. These results are likely explained by the expelled symbionts in the mucus of bleached individuals. Our study suggests that coral bleaching could immediately impact the nutrient flux in the coral reef ecosystem via its effect on coral mucus
Building consensus around the assessment and interpretation of Symbiodiniaceae diversity
Within microeukaryotes, genetic variation and functional variation sometimes accumulate more quickly than morphological differences. To understand the evolutionary history and ecology of such lineages, it is key to examine diversity at multiple levels of organization. In the dinoflagellate family Symbiodiniaceae, which can form endosymbioses with cnidarians (e.g., corals, octocorals, sea anemones, jellyfish), other marine invertebrates (e.g., sponges, molluscs, flatworms), and protists (e.g., foraminifera), molecular data have been used extensively over the past three decades to describe phenotypes and to make evolutionary and ecological inferences. Despite advances in Symbiodiniaceae genomics, a lack of consensus among researchers with respect to interpreting genetic data has slowed progress in the field and acted as a barrier to reconciling observations. Here, we identify key challenges regarding the assessment and interpretation of Symbiodiniaceae genetic diversity across three levels: species, populations, and communities. We summarize areas of agreement and highlight techniques and approaches that are broadly accepted. In areas where debate remains, we identify unresolved issues and discuss technologies and approaches that can help to fill knowledge gaps related to genetic and phenotypic diversity. We also discuss ways to stimulate progress, in particular by fostering a more inclusive and collaborative research community. We hope that this perspective will inspire and accelerate coral reef science by serving as a resource to those designing experiments, publishing research, and applying for funding related to Symbiodiniaceae and their symbiotic partnerships.journal articl
Building consensus around the assessment and interpretation of Symbiodiniaceae diversity
Within microeukaryotes, genetic variation and functional variation sometimes accumulate more quickly than morphological differences. To understand the evolutionary history and ecology of such lineages, it is key to examine diversity at multiple levels of organization. In the dinoflagellate family Symbiodiniaceae, which can form endosymbioses with cnidarians (e.g., corals, octocorals, sea anemones, jellyfish), other marine invertebrates (e.g., sponges, molluscs, flatworms), and protists (e.g., foraminifera), molecular data have been used extensively over the past three decades to describe phenotypes and to make evolutionary and ecological inferences. Despite advances in Symbiodiniaceae genomics, a lack of consensus among researchers with respect to interpreting genetic data has slowed progress in the field and acted as a barrier to reconciling observations. Here, we identify key challenges regarding the assessment and interpretation of Symbiodiniaceae genetic diversity across three levels: species, populations, and communities. We summarize areas of agreement and highlight techniques and approaches that are broadly accepted. In areas where debate remains, we identify unresolved issues and discuss technologies and approaches that can help to fill knowledge gaps related to genetic and phenotypic diversity. We also discuss ways to stimulate progress, in particular by fostering a more inclusive and collaborative research community. We hope that this perspective will inspire and accelerate coral reef science by serving as a resource to those designing experiments, publishing research, and applying for funding related to Symbiodiniaceae and their symbiotic partnerships
Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTICâHF: baseline characteristics and comparison with contemporary clinical trials
Aims:
The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTICâHF) trial. Here we describe the baseline characteristics of participants in GALACTICâHF and how these compare with other contemporary trials.
Methods and Results:
Adults with established HFrEF, New York Heart Association functional class (NYHA)ââ„âII, EF â€35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokineticâguided dosing: 25, 37.5 or 50âmg bid). 8256 patients [male (79%), nonâwhite (22%), mean age 65âyears] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NTâproBNP 1971âpg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTICâHF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressureâ<â100âmmHg (n = 1127), estimated glomerular filtration rate <â30âmL/min/1.73 m2 (n = 528), and treated with sacubitrilâvalsartan at baseline (n = 1594).
Conclusions:
GALACTICâHF enrolled a wellâtreated, highârisk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation
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The graying of America and outdoor recreation planning: Providing accessible outdoor recreation for older persons
As baby boomers age, the population of the United States moves toward a higher proportion of elderly than ever before. These seniors retire earlier, have more discretionary income, active lifestyles and education. They also have a growing interest in fitness--challenging future outdoor recreation planning. Providers of public outdoor recreation, including the U.S.D.A. Forest Service, are under pressure to accommodate all population groups--including seniors. An emerging problem for recreation planners is how to address the special needs generated by this important demographic shift. To explore this issue, the author studied the retirement community Green Valley, Arizona's influence on the Forest Service's Madera Canyon Recreation Area. The study identified Madera Canyon as a model for successful recreation planning by enlisting volunteers, encouraging user participation, providing trails with different experiences, benches, wildlife viewing, and educational opportunities in natural areas, to meet senior's needs. The author provides planning guidelines
Reproductive histology and energetics in Acropora hyacinthus in response to the 2019 Moorea bleaching event.
Dataset: Acropora hyacinthus energetics and reproductionThe French Polynesian island of Moâorea experienced a severe mass bleaching event in 2019 accompanied by widespread coral mortality. At the most heavily impacted sites, Acropora hyacinthus individuals that were resistant to bleaching were observed alongside colonies that bleached but showed signs of symbiont recovery shortly after the bleaching event. Fragments of healthy A. hyacinthus colonies five months post-bleaching were sampled for energetic assays and histological measurements. Despite healthy appearances in both resistant and recovered corals, recovered colonies had significantly reduced energy reserves compared to resistant colonies. In addition, compound effects of stress on reproduction were observed: recovered colonies displayed both a lower probability of containing gametes and lower fecundity per polyp.
For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/876072NSF Division of Ocean Sciences (NSF OCE) OCE-1935308, NSF Division of Ocean Sciences (NSF OCE) OCE-193530
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