Combined and independent effects of hypoxia and tributyltin on mRNA expression and physiology of the Eastern oyster (Crassostrea virginica)

© 2020, The Author(s). Oyster reefs are vital to estuarine health, but they experience multiple stressors and globally declining populations. This study examined effects of hypoxia and tributyltin (TBT) on adult Eastern oysters (Crassostrea virginica) exposed either in the laboratory or the field following a natural hypoxic event. In the laboratory, oysters were exposed to either hypoxia followed by a recovery period, or to hypoxia combined with TBT. mRNA expression of HIF1-α and Tβ-4 along with hemocyte counts, biomarkers of hypoxic stress and immune health, respectively, were measured. In field-deployed oysters, HIF1-α and Tβ-4 expression increased, while no effect on hemocytes was observed. In contrast, after 6 and 8 days of laboratory-based hypoxia exposure, both Tβ-4 expression and hemocyte counts declined. After 8 days of exposure to hypoxia + TBT, oysters substantially up-regulated HIF1-α and down-regulated Tβ-4, although hemocyte counts were unaffected. Results suggest that hypoxic exposure induces immunosuppression which could increase vulnerability to pathogens

Combined and Independent Effects On Hypoxia and Tributylin On mRNA Expression and Physiology of the Eastern Oyster (\u3ci\u3eCrassostrea virginica\u3c/i\u3e)

Oyster reefs are vital to estuarine health, but they experience multiple stressors and globally declining populations. This study examined effects of hypoxia and tributyltin (TBT) on adult Eastern oysters (Crassostrea virginica) exposed either in the laboratory or the field following a natural hypoxic event. In the laboratory, oysters were exposed to either hypoxia followed by a recovery period, or to hypoxia combined with TBT. mRNA expression of HIF1-α and Tβ-4 along with hemocyte counts, biomarkers of hypoxic stress and immune health, respectively, were measured. In field-deployed oysters, HIF1-α and Tβ-4 expression increased, while no effect on hemocytes was observed. In contrast, after 6 and 8 days of laboratory-based hypoxia exposure, both Tβ-4 expression and hemocyte counts declined. After 8 days of exposure to hypoxia + TBT, oysters substantially up-regulated HIF1-α and down-regulated Tβ-4, although hemocyte counts were unaffected. Results suggest that hypoxic exposure induces immunosuppression which could increase vulnerability to pathogens

Exposure to Oil and Hypoxia Results In Alterations of Immune Transcriptional Patterns In Developing Sheepshead Minnows (\u3ci\u3eCyprinodon variegatus\u3c/i\u3e)

The area and timing of the Deepwater Horizon oil spill highlight the need to study oil and hypoxia exposure in early life stage fishes. Though critical to health, little research has targeted the effect of oil and hypoxia exposure on developing immune systems. To this end, we exposed sheepshead minnows (Cyprinodon variegatus) at three early life stages: embryonic; post-hatch; and post-larval, to a high energy water accommodated fraction (HEWAF) of oil, hypoxia, or both for 48 hours. We performed RNAseq to understand how exposures alter expression of immune transcripts and pathways. Under control conditions, the embryonic to post-hatch comparison (first transition) had a greater number of significantly regulated immune pathways than the second transition (post-hatch to post-larval). The addition of oil had little effect in the first transition, however, hypoxia elicited changes in cellular and humoral immune responses. In the second transition, oil exposure significantly altered many immune pathways (43), and while hypoxia altered few pathways, it did induce a unique signature of generally suppressing immune pathways. These data suggest that timing of exposure to oil and/or hypoxia matters, and underscores the need to further investigate the impacts of multiple stressors on immune system development in early life stage fishes

Dispersed Crude Oil Induces Dysbiosis In the Red Snapper \u3ci\u3eLutjanus campechanus\u3c/i\u3e External Microbiota

The fish external microbiota competitively excludes primary pathogens and prevents the proliferation of opportunists. A shift from healthy microbiota composition, known as dysbiosis, may be triggered by environmental stressors and increases host susceptibility to disease. The Deepwater Horizon (DWH) oil spill was a significant stressor event in the Gulf of Mexico. Despite anecdotal reports of skin lesions on fishes following the oil spill, little information is available on the impact of dispersed oil on the fish external microbiota. In this study, juvenile red snapper (Lutjanus campechanus) were exposed to a chemically enhanced water-accommodated fraction (CEWAF) of Corexit 9500/DWH oil (CEWAF) and/or the bacterial pathogen Vibrio anguillarum in treatments designed to detect changes in and recovery of the external microbiota. In fish chronically exposed to CEWAF, immunoglobulin M (IgM) expression significantly decreased between 2 and 4 weeks of exposure, coinciding with elevated liver total polycyclic aromatic hydrocarbons (PAHs). Dysbiosis was detected on fish chronically exposed to CEWAF compared to seawater controls, and addition of a pathogen challenge altered the final microbiota composition. Dysbiosis was prevented by returning fish to clean seawater for 21 days after 1 week of CEWAF exposure. Four fish exhibited lesions during the trial, all of which were exposed to CEWAF but not all of which were exposed to V. anguillarum. This study indicates that month-long exposure to dispersed oil leads to dysbiosis in the external microbiota. As the microbiota is vital to host health, these effects should be considered when determining the total impacts of pollutants in aquatic ecosystems

Queen Conch (Strombus gigas) Testis Regresses during the Reproductive Season at Nearshore Sites in the Florida Keys

BACKGROUND: Queen conch (Strombus gigas) reproduction is inhibited in nearshore areas of the Florida Keys, relative to the offshore environment where conchs reproduce successfully. Nearshore reproductive failure is possibly a result of exposure to environmental factors, including heavy metals, which are likely to accumulate close to shore. Metals such as Cu and Zn are detrimental to reproduction in many mollusks. METHODOLOGY/PRINCIPAL FINDINGS: Histology shows gonadal atrophy in nearshore conchs as compared to reproductively healthy offshore conchs. In order to determine molecular mechanisms leading to tissue changes and reproductive failure, a microarray was developed. A normalized cDNA library for queen conch was constructed and sequenced using the 454 Life Sciences GS-FLX pyrosequencer, producing 27,723 assembled contigs and 7,740 annotated transcript sequences. The resulting sequences were used to design the microarray. Microarray analysis of conch testis indicated differential regulation of 255 genes (p<0.01) in nearshore conch, relative to offshore. Changes in expression for three of four transcripts of interest were confirmed using real-time reverse transcription polymerase chain reaction. Gene Ontology enrichment analysis indicated changes in biological processes: respiratory chain (GO:0015992), spermatogenesis (GO:0007283), small GTPase-mediated signal transduction (GO:0007264), and others. Inductively coupled plasma-mass spectrometry analysis indicated that Zn and possibly Cu were elevated in some nearshore conch tissues. CONCLUSIONS/SIGNIFICANCE: Congruence between testis histology and microarray data suggests that nearshore conch testes regress during the reproductive season, while offshore conch testes develop normally. Possible mechanisms underlying the testis regression observed in queen conch in the nearshore Florida Keys include a disruption of small GTPase (Ras)-mediated signaling in testis development. Additionally, elevated tissue levels of Cu (34.77 ng/mg in testis) and Zn (831.85 ng/mg in digestive gland, 83.96 ng/mg in testis) nearshore are similar to reported levels resulting in reproductive inhibition in other gastropods, indicating that these metals possibly contribute to NS conch reproductive failure

A review of the toxicology of oil in vertebrates : what we have learned following the Deepwater Horizon oil spill

This research was made possible by a grant from The Gulf of Mexico Research Initiative. This publication is UMCES contribution No. 6045 and Ref. No. [UMCES] CBL 2022-008. This is National Marine Mammal Foundation Contribution #314 to peer-reviewed scientific literature.In the wake of the Deepwater Horizon (DWH) oil spill, a number of government agencies, academic institutions, consultants, and nonprofit organizations conducted lab- and field-based research to understand the toxic effects of the oil. Lab testing was performed with a variety of fish, birds, turtles, and vertebrate cell lines (as well as invertebrates); field biologists conducted observations on fish, birds, turtles, and marine mammals; and epidemiologists carried out observational studies in humans. Eight years after the spill, scientists and resource managers held a workshop to summarize the similarities and differences in the effects of DWH oil on vertebrate taxa and to identify remaining gaps in our understanding of oil toxicity in wildlife and humans, building upon the cross-taxonomic synthesis initiated during the Natural Resource Damage Assessment. Across the studies, consistency was found in the types of toxic response observed in the different organisms. Impairment of stress responses and adrenal gland function, cardiotoxicity, immune system dysfunction, disruption of blood cells and their function, effects on locomotion, and oxidative damage were observed across taxa. This consistency suggests conservation in the mechanisms of action and disease pathogenesis. From a toxicological perspective, a logical progression of impacts was noted: from molecular and cellular effects that manifest as organ dysfunction, to systemic effects that compromise fitness, growth, reproductive potential, and survival. From a clinical perspective, adverse health effects from DWH oil spill exposure formed a suite of signs/symptomatic responses that at the highest doses/concentrations resulted in multi-organ system failure.Publisher PDFPeer reviewe

Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Simultaneous Exposure to Chronic Hypoxia and Dissolved Polycyclic Aromatic Hydrocarbons Results in Reduced Egg Production and Larval Survival in the Sheepshead Minnow (\u3ci\u3eCyprinodon variegatus\u3c/i\u3e)

Estuarine fish in the northern Gulf of Mexico are exposed annually to hypoxic conditions. In addition to hypoxia, fish located throughout the northern Gulf of Mexico were potentially exposed to oil released during the Deepwater Horizon incident. Therefore, the interaction between oil exposure and hypoxia is worth investigating. To examine this interaction, the authors exposed adult and larval sheepshead minnow (Cyprinodon variegatus) to crude or dispersed oil under both normoxic and hypoxic conditions. The authors examined total egg production, egg hatching success, and larval survival post hatch. The authors\u27 results indicate that co-exposure to crude or dispersed oil and hypoxia resulted in a significant decrease in egg production, as well as a significant decrease in both egg hatch success and larval survival post hatch. The significant impact on reproductive success following crude or dispersed oil and hypoxia exposure indicates the importance of including environmental parameters such as hypoxia when evaluating the impact of an oil spill. (c) 2015 SETA

Oil and Hypoxia Alter DNA Methylation and Transcription of Genes Related To Neurological Function In Larval \u3ci\u3eCyprinodon variegatus\u3c/i\u3e

DNA methylation is an important epigenetic mark involved in modulating transcription. While multiple studies document the ability of environmental stressors to alter methylation patterns, there is little information regarding the effects of oil and hypoxia on the methylome. Oil and hypoxic stress are threats in coastal ecosystems, which act as nursery habitats for developing fish. To explore the methylation altering effects of oil and hypoxia on developing fish, we exposed larval Cyprinodon variegatus to oil, hypoxia, or both for 48 h followed by 48 h of depuration in clean, normoxic conditions. We then used immunoprecipitation coupled with high-throughput sequencing (MeDIP seq) to evaluate genome-wide methylation changes. We also performed RNA seq to associate methylation and altered transcription. Oil and hypoxia together elicited greater impacts to methylation than either stressor individually. Additionally, the oil+hypoxia treatment exhibited an overlap between differentially methylated regions and differential gene expression at 20 loci. Functional analyses of these loci revealed enrichment of processes related to neurological function and development. Two neurological genes (slc1a2, asxl2) showed altered methylation of promoter CpG islands and transcriptional changes, suggesting epigenetic modulation of gene expression. Our results suggest a possible mechanism explaining altered behavior patterns noted in fish following oil exposure