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Climate change accelerates coral reef decline and jeopardizes recruitment essential for ecosystem recovery. Adult corals rely on a vital nutritional exchange with their symbiotic algae (Symbiodiniaceae), but the dynamics of reliance from fertilization to recruitment are understudied. We investigated the physiological, metabolomic, and transcriptomic changes across 13 developmental stages of Montipora capitata, a coral in Hawaiʻi that inherits symbionts from parent to egg. We found that embryonic development depends on maternally provisioned mRNAs and lipids, with a rapid shift to symbiont-derived nutrition in late developmental stages. Symbiont density and photosynthesis peak in swimming larvae to fuel pelagic dispersal. By contrast, respiratory demand increases significantly during metamorphosis and settlement, reflecting this energy-intensive morphological reorganization. Symbiont proliferation is driven by symbiont ammonium assimilation in larval stages with little evidence of nitrogen metabolism in the coral host. As development progresses, the host enhances nitrogen sequestration, regulating symbiont populations, and ensuring the transfer of fixed carbon to support metamorphosis, with both metabolomic and transcriptomic indicators of increased carbohydrate availability. Although algal symbiont community composition remained stable, bacterial communities shifted with ontogeny, associated with holobiont metabolic reorganization. Our study reveals extensive metabolic changes during development with increasing reliance on symbiont nutrition. Metamorphosis and settlement emerge as critical periods of energetic vulnerability to projected climate scenarios that destabilize symbiosis. This highly detailed characterization of symbiotic nutritional exchange during sensitive early life stages provides essential knowledge for understanding and forecasting the function of nutritional symbioses and, specifically, coral survival and recruitment in a future of climate change. 

Coral reefs, one of the most diverse ecosystems in the world, face increasing pressures from global and local anthropogenic stressors. Therefore, a better understanding of the ecological ramifications of warming and land-based inputs (e.g., sedimentation and nutrient loading) on coral reef ecosystems is necessary. In this study, we measured how a natural nutrient and sedimentation gradient affected multiple facets of coral functionality, including endosymbiont and coral host response variables, holobiont metabolic responses, and percent cover of Pocillopora acuta colonies in Mo'orea, French Polynesia. We used thermal performance curves to quantify the relationship between metabolic rates and temperature along the environmental gradient. We found that algal endosymbiont % nitrogen content, endosymbiont densities, and total chlorophyll a content increased with nutrient input, while endosymbiont nitrogen content cell−1 decreased, likely representing competition among the algal endosymbionts. Nutrient and sediment loading decreased coral metabolic responses to thermal stress in terms of their thermal performance and metabolic rate processes. The acute thermal optimum for dark respiration decreased, along with the maximal performance for gross photosynthetic and calcification rates. Gross photosynthetic and calcification rates normalized to a reference temperature (26.8 °C) decreased along the gradient. Lastly, percent cover of P. acuta colonies decreased by nearly two orders of magnitude along the nutrient gradient. These findings illustrate that nutrient and sediment loading affect multiple levels of coral functionality. Understanding how local-scale anthropogenic stressors influence the responses of corals to temperature can inform coral reef management, particularly on the mediation of land-based inputs into coastal coral reef ecosystems. 

Abstract Genetic mutations to the Lamin A/C gene (LMNA) can cause heart disease, but the mechanisms making cardiac tissues uniquely vulnerable to the mutations remain largely unknown. Further, patients withLMNAmutations have highly variable presentation of heart disease progression and type.In vitropatient-specific experiments could provide a powerful platform for studying this phenomenon, but the use of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) introduces heterogeneity in maturity and function thus complicating the interpretation of the results of any single experiment. We hypothesized that integrating single cell RNA sequencing (scRNA-seq) with analysis of the tissue architecture and contractile function would elucidate some of the probable mechanisms. To test this, we investigated five iPSC-CM lines, three controls and two patients with a (c.357-2A>G) mutation. The patient iPSC-CM tissues had significantly weaker stress generation potential than control iPSC-CM tissues demonstrating the viability of ourin vitroapproach. Through scRNA-seq, differentially expressed genes between control and patient lines were identified. Some of these genes, linked to quantitative structural and functional changes, were cardiac specific, explaining the targeted nature of the disease progression seen in patients. The results of this work demonstrate the utility of combiningin vitrotools in exploring heart disease mechanics.