Biology subjects

Vadopalas, B.

Publications and source records attributed to Vadopalas, B..

8 recordsLinked to original sources

bioRxiv2023

Triploid Pacific oysters exhibit stress response dysregulation and elevated mortality following marine heatwaves

Polyploidy has been shown to negatively impact environmental stress tolerance, resulting in increased susceptibility to extreme climate events such as marine heatwaves (MHWs). In this study, we used the response of the Pacific oyster Crassostrea gigas to MHWs as a model system to identify key ploidy-specific differences in the physiological and transcriptomic response of oysters to environmental stress. In this study, adult diploid (2n) and triploid (3n) oysters were exposed to elevated seawater temperature (single stressor; 30{degrees}C), elevated temperature followed by acute desiccation stress (multiple stressor; 30{degrees}C + emersion at an aerial temperature of 44{degrees}C for 4h), or a control (17{degrees}C) within a hatchery setting. Oyster mortality rate was elevated within stress treatments with respect to the control and was significantly higher in triploids than diploids following multiple stress exposure (36.4% vs. 14.8%). Triploids within the multiple stressor treatment exhibited signs of energetic limitation, including metabolic depression, a significant reduction in ctenidium Na+/K+ ATPase activity, and the dysregulated expression of key genes associated with heat tolerance, the inhibition of apoptosis, and mitochondrial function. Functional enrichment analysis of ploidy-specific gene sets identified that biological processes associated with metabolism, stress tolerance, and immune function were overrepresented within triploids across stress treatments. Our results demonstrate that triploidy impacts the transcriptional regulation of key metabolic processes that underly the environmental stress response of Pacific oysters, resulting in downstream shifts in physiological tolerance limits that may be detrimental to survival. The impact of chromosome set manipulation on the climate resilience of marine populations has important implications for the adaptability of marine populations and domestic food security within future climate scenarios, especially as triploidy induction becomes an increasingly popular tool to elicit reproductive control across a wide range of marine organisms used within marine aquaculture.

genomics↗

bioRxiv2022

Dynamic DNA methylation contributes to carryover effects and beneficial acclimatization in geoduck clams

Given the rapidly changing global climate, there is a growing need to understand the acclimatory basis of animal response to environmental change. To investigate the role of DNA methylation in environmental acclimatization, we generated a reference genome and surveyed the physiology and DNA methylomes of juvenile geoduck clams, Panopea generosa, under differing seawater pH regimes. Juveniles were initially exposed to one of three seawater pH conditions, followed by ambient common-garden conditions, then a second reciprocal exposure to ambient pH or pH 7.4. Within 10 days of the initial low pH exposure, juvenile clams showed decreased shell size relative to ambient pH with corresponding differential DNA methylation. Following four months of ambient common-garden conditions, juveniles initially exposed to low pH compensatorily grew larger, with DNA methylation indicative of these phenotypic differences, demonstrating epigenetic carryover effects persisted months after initial exposure. Functional enrichment analysis of differentially methylated genes revealed regulation of signal transduction through widespread changes in the Wnt signaling pathways that influence cell growth, proliferation, tissue and skeletal formation, and cytoskeletal change. After 10 days of secondary exposure to pH 7.4, naive juvenile clams were more sensitive to low pH compared to those initially exposed, showing reduced growth and having nearly a 2-fold greater change in DNA methylation. Collectively, this new genomic resource and coordinated phenotypic and methylomic response support that epigenetic mechanisms underlie acclimatization to provide beneficial phenotypes.

genomics↗

bioRxiv2020

Repeat exposure to hypercapnic seawater modifies performance and oxidative status in a tolerant burrowing clam

Moderate oxidative stress is a hypothesized driver of enhanced stress tolerance and lifespan. Whereas thermal stress, irradiance, and dietary restriction show evidence of dose-dependent benefits for many taxa, stress acclimation remains understudied in marine invertebrates, despite being threatened by climate change stressors such as ocean acidification. To test for life-stage and stress-intensity dependence in eliciting enhanced tolerance under subsequent stress encounters, we initially conditioned pediveliger Pacific geoduck (Panopea generosa) larvae to (i) ambient and moderately elevated pCO2 (920 atm and 2800 atm, respectively) for 110 days, (ii) secondarily applied a 7-day exposure to ambient, moderate, and severely elevated pCO2 (750 atm, 2800 atm, and 4900 atm, respectively), followed by 7 days in ambient conditions, and (iii) implemented a modified-reciprocal 7-day tertiary exposure to ambient (970 atm) and moderate pCO2 (3000 atm). Initial conditioning to moderate pCO2 stress followed by secondary and tertiary exposure to severe and moderate pCO2 stress increased respiration rate, organic biomass, and shell size suggesting a stress-intensity-dependent effect on energetics. Additionally, stress-acclimated clams had lower antioxidant capacity compared to clams under initial ambient conditions, supporting the hypothesis that stress over postlarval-to-juvenile development affects oxidative status later in life. We posit two subcellular mechanisms underpinning stress-intensity-dependent effects on mitochondrial pathways and energy partitioning: i) stress-induced attenuation of mitochondrial function and ii) adaptive mitochondrial shift under moderate stress. Time series and stress intensity-specific approaches can reveal life-stages and magnitudes of exposure, respectively, that may elicit beneficial phenotypic variation. Summary statementHypercapnic conditions during postlarval development improves physiological performance and oxidative status. This novel investigation of adaptive stress acclimation highlights the plasticity of bioenergetic and subcellular responses in Panopea generosa.

physiology↗

bioRxiv2020

Temporal proteomic profiling reveals insight into critical developmental processes and temperature-influenced physiological response differences in a bivalve mollusc

BackgroundProtein expression patterns underlie physiological processes and phenotypic differences including those occurring during early development. The Pacific oyster (Crassostrea gigas) undergoes a major phenotypic change in early development from free-swimming larval form to sessile benthic dweller while proliferating in environments with broad temperature ranges. Despite the economic and ecological importance of the species, physiological processes occurring throughout metamorphosis and the impact of temperature on these processes have not yet been mapped out. ResultsTowards this, we comprehensively characterized protein abundance patterns for 7978 proteins throughout metamorphosis in the Pacific oyster at different temperature regimes. We used a multi-statistical approach including principal component analysis, ANOVA-simultaneous component analysis, and hierarchical clustering coupled with functional enrichment analysis to characterize these data. We identified distinct sets of proteins with time-dependent abundances generally not affected by temperature. Over 12 days, adhesion and calcification related proteins acutely decreased, organogenesis and extracellular matrix related proteins gradually decreased, proteins related to signaling showed sinusoidal abundance patterns, and proteins related to metabolic and growth processes gradually increased. Contrastingly, different sets of proteins showed temperature-dependent abundance patterns with proteins related to immune response showing lower abundance and catabolic pro-growth processes showing higher abundance in animals reared at 29{degrees}C relative to 23{degrees}C. ConclusionAlthough time was a stronger driver than temperature of metamorphic proteome changes, temperature-induced proteome differences led to pro-growth physiology corresponding to larger oyster size at 29{degrees}C, and to altered specific metamorphic processes and possible pathogen presence at 23{degrees}C. These findings offer high resolution insight into why oysters may experience high mortality rates during this life transition in both field and culture settings. The proteome resource generated by this study provides data-driven guidance for future work on developmental changes in molluscs. Furthermore, the analytical approach taken here provides a foundation for effective shotgun proteomic analyses across a variety of taxa.

developmental biology↗

bioRxiv2019

Metabolic recovery and compensatory shell growth of juvenile Pacific geoduck Panopea generosa following short-term exposure to acidified seawater

While acute stressors can be detrimental, environmental stress conditioning can improve performance. To test the hypothesis that physiological status is altered by stress conditioning, we subjected juvenile Pacific geoduck, Panopea generosa, to repeated exposures of elevated pCO2 in a commercial hatchery setting followed by a period in ambient common garden. Respiration rate and shell length were measured for juvenile geoduck periodically throughout short-term repeated reciprocal exposure periods in ambient (~550 {micro}atm) or elevated (~2400 {micro}atm) pCO2 treatments and in common, ambient conditions, five months after exposure. Short-term exposure periods comprised an initial 10-day exposure followed by 14 days in ambient before a secondary 6-day reciprocal exposure. The initial exposure to elevated pCO2 significantly reduced respiration rate by 25% relative to ambient conditions, but no effect on shell growth was detected. Following 14 days in common garden, ambient conditions, reciprocal exposure to elevated or ambient pCO2 did not alter juvenile respiration rates, indicating ability for metabolic recovery under subsequent conditions. Shell growth was negatively affected during the reciprocal treatment in both exposure histories, however clams exposed to the initial elevated pCO2 showed compensatory growth with 5.8% greater shell length (on average between the two secondary exposures) after five months in ambient conditions. Additionally, clams exposed to the secondary elevated pCO2 showed 52.4% increase in respiration rate after five months in ambient conditions. Early exposure to low pH appears to trigger carry-over effects suggesting bioenergetic re-allocation facilitates growth compensation. Life stage-specific exposures to stress can determine when it may be especially detrimental, or advantageous, to apply stress conditioning for commercial production of this long-lived burrowing clam. Lay summaryCommercial shellfish hatcheries provide essential food security, but often production can be hampered by sensitivity of shellfish at early life stages. Repeated short-term exposures can increase tolerance and performance of the geoduck clam with implications for sustainable aquaculture.

physiology↗

bioRxiv2019

Dynamic Response in the Larval Geoduck Clam Proteome to Elevated pCO2

Pacific geoduck clams (Panopea generosa) are found along the Northeast Pacific coast where they are significant components of coastal and estuarine ecosystems and the basis of a growing and highly profitable aquaculture industry. The Pacific coastline, however, is also the sight of rapidly changing ocean habitat, including significant reductions in pH. The impacts of ocean acidification on invertebrate bivalve larvae have been widely documented and it is well established that many species experience growth and developmental deficiencies when exposed to low pH. As a native of environments that have historically lower pH than the open ocean, it is possible that geoduck larvae are less impacted by these effects than other species. Over two weeks in larval development (days 6-19 post-fertilization) geoduck larvae were reared at pH 7.5 or 7.1 in a commercial shellfish hatchery. Larvae were sampled at six time points throughout the period for a in-depth proteomics analysis of developmental molecular physiology. Larvae reared at low pH were smaller than those reared at ambient pH, especially in the prodissoconch II phase of development. Competency for settlement was also delayed in larvae from the low pH conditions. A comparison of proteomic profiles over the course of development reveal that these differing phenotypic outcomes are likely due to environmental disruptions to the timing of molecular physiological events as suites of proteins showed differing profiles of abundance between the two pH environments. Ocean acidification likely caused an energetic stress on the larvae at pH 7.1, causing a shift in physiological prioritization with resulting loss of fitness.

molecular biology↗

bioRxiv2018

Characterization of Pacific oyster (Crassostrea gigas) proteomic response to natural environmental differences

Global climate change is rapidly altering coastal marine ecosystems important for food production. A comprehensive understanding of how organisms will respond to these complex environmental changes can come only from observing and studying species within their natural environment. To this end, the effects of environmental drivers -- pH, dissolved oxygen content, salinity, and temperature -- on Pacific oyster (Crassostrea gigas) physiology were evaluated in an outplant experiment. Sibling juvenile oysters were outplanted to eelgrass and unvegetated habitat at five different estuarine sites within the Acidification Nearshore Monitoring Network in Washington State, USA to evaluate how regional environmental drivers influence molecular physiology. Within each site, we also determined if eelgrass presence that buffered pH conditions changed the oysters expressed proteome. A novel, two-step, gel-free proteomic approach was used to identify differences in protein abundance in C. gigas ctenidia tissue after a 29 day outplant by 1) identifying proteins in a data independent acquisition survey step and 2) comparing relative quantities of targeted environmental response proteins using selected reaction monitoring. While there was no difference in protein abundance detected between habitats or among sites within Puget Sound, C. gigas outplanted at Willapa Bay had significantly higher abundances of antioxidant enzymes and molecular chaperones. Environmental factors at Willapa Bay, such as higher average temperature, may have driven this protein abundance pattern. These findings generate a suite of new hypotheses for lab and field experiments to compare the effects of regional conditions on physiological responses of marine invertebrates.

ecology↗

bioRxiv2016

Integrating proteomics and selected reaction monitoring to develop a non-invasive assay for geoduck reproductive maturation

Geoduck clams (Panopea generosa) are an increasingly important fishery and aquaculture product along the eastern Pacific coast from Baja California, Mexico to Alaska. These long-lived clams are highly fecund, though sustainable hatchery production of genetically diverse larvae is hindered by the lack of sexual dimorphism, resulting in asynchronous spawning of broodstock, unequal sex ratios, and low numbers of breeders. Development of assays of gonad physiology could indicate sex and maturation stage, as well as be used to assess the status of natural populations. Proteomic profiles were determined for three reproductive maturation stages in both male and female clams using data dependent acquisition (DDA) of gonad proteins. Gonad proteomes became increasingly divergent between males and females as maturation progressed. The DDA data was used to develop targets analyzed with selected reaction monitoring (SRM) in gonad tissue as well as hemolymph. The SRM assay yielded a suite of indicator peptides that can be used as an efficient assay to determine geoduck gonad maturation status. Application of SRM in hemolymph samples demonstrates this procedure could effectively be used to assess reproductive status in marine mollusks in a non-lethal manner.

physiology↗