Exposure to low pH induces molecular level changes in the marine worm, Platynereis dumerilii

© 2015 Elsevier Inc. Fossil fuel emissions and changes in net land use lead to an increase in atmospheric CO 2 concentration and a subsequent decrease of ocean pH. Noticeable effects on organisms' calcification rate, shell structure and energy metabolism have been reported in the literature. To date, little is known about the molecular mechanisms altered under low pH exposure, especially in non-calcifying organisms. We used a suppression subtractive hybridisation (SSH) approach to characterise differentially expressed genes isolated from Platynereis dumerilii, a non-calcifying marine polychaeta species, kept at normal and low pH conditions. Several gene sequences have been identified as differentially regulated. These are involved in processes previously considered as indicators of environment change, such as energy metabolism (NADH dehydrogenase, 2-oxoglutarate dehydrogenase, cytochrome c oxidase and ATP synthase subunit F), while others are involved in cytoskeleton function (paramyosin and calponin) and immune defence (fucolectin-1 and paneth cell-specific alpha-defensin) processes. This is the first study of differential gene expression in a non-calcifying, marine polychaete exposed to low pH seawater conditions and suggests that mechanisms of impact may include additional pathways not previously identified as impacted by low pH in other species

Microplastic contamination of drinking water: a systematic review.

BackgroundMicroplastics (MPs) are omnipresent in the environment, including the human food chain; a likely important contributor to human exposure is drinking water.ObjectiveTo undertake a systematic review of MP contamination of drinking water and estimate quantitative exposures.MethodsThe protocol for the systematic review employed has been published in PROSPERO (PROSPERO 2019, Registration number: CRD42019145290). MEDLINE, EMBASE and Web of Science were searched from launch to the 3rd of June 2020, selecting studies that used procedural blank samples and a validated method for particle composition analysis. Studies were reviewed within a narrative analysis. A bespoke risk of bias (RoB) assessment tool was used.Results12 studies were included in the review: six of tap water (TW) and six of bottled water (BW). Meta-analysis was not appropriate due to high statistical heterogeneity (I 2 >95%). Seven studies were rated low RoB and all confirmed MP contamination of drinking water. The most common polymers identified in samples were polyethylene terephthalate (PET) and polypropylene (PP), Methodological variability was observed throughout the experimental protocols. For example, the minimum size of particles extracted and analysed, which varied from 1 to 100 μm, was seen to be critical in the data reported. The maximum reported MP contamination was 628 MPs/L for TW and 4889 MPs/L for BW, detected in European samples. Based on typical consumption data, this may be extrapolated to a maximum yearly human adult uptake of 458,000 MPs for TW and 3,569,000 MPs for BW.ConclusionsThis is the first systematic review that appraises the quality of existing evidence on MP contamination of drinking water and estimates human exposures. The precautionary principle should be adopted to address concerns on possible human health effects from consumption of MPs. Future research should aim to standardise experimental protocols to aid comparison and elevate quality

Short-term effects of CO₂-induced low pH exposure on target gene expression in Platynereis dumerilii

Objective: Increasing atmospheric CO₂ concentration are causing changes to the seawater carbonate chemistry, lowering the pH and we study potential impacts of these changes at the molecular level in a non-calcifying, marine polychaete species Platynereis dumerilii. Methods: we investigate the relative expression of carbonic anhydrase (CA), Na+/H+ exchangers (NHE), and calmodulin (CaM) genes from P. dumerilii under acidified seawater conditions (pH 7.8) induced by CO₂ using qPCR. Results: mRNA expression of CA in the CO₂-induced worms was significantly up-regulated at low pH conditions (pH 7.8, 1h), suggesting changes in acid-base balance. In contrast, the expression of NHE and CaM showed no significant change. In addition, we compare these results to a previous study using inorganic acid (HCl)-induced pH changes. Conclusions: results suggest that carbonate chemistry has an impact on gene expression that differs from pH-associated change. To our knowledge, this is the first study that compares low pH exposure experiments using HCl and CO₂ as the inducing agents

Genetic alterations and cancer formation in a European flatfish at sites of different contamination burdens

Fish diseases are an indicator for marine ecosystem health since they provide a biological end-point of historical exposure to stressors. Liver cancer has been used to monitor the effects of exposure to anthropogenic pollution in flatfish for many years. The prevalence of liver cancer can exceed 20%. Despite the high prevalence and the opportunity of using flatfish to study environmentally induced cancer, the genetic and environmental factors driving tumor prevalence across sites are poorly understood. This study aims to define the link between genetic deterioration, liver disease progression, and anthropogenic contaminant exposures in the flatfish dab (Limanda limanda). We assessed genetic changes in a conserved cancer gene, Retinoblastoma (Rb), in association with histological diagnosis of normal, pretumor, and tumor pathologies in the livers of 165 fish from six sites in the North Sea and English Channel. The highest concentrations of metals (especially cadmium) and organic chemicals correlated with the presence of tumor pathology and with defined genetic profiles of the Rb gene, from these sites. Different Rb genetic profiles were found in liver tissue near each tumor phenotype, giving insight into the mechanistic molecular-level cause of the liver pathologies. Different Rb profiles were also found at sampling sites of differing contaminant burdens. Additionally, profiles indicated that histological “normal” fish from Dogger sampling locations possessed Rb profiles associated with pretumor disease. This study highlights an association between Rb and specific contaminants (especially cadmium) in the molecular etiology of dab liver tumorigenesis

Microplastic contamination of seafood intended for human consumption: a systematic review and meta-analysis

Background: Microplastics (MPs) have contaminated all compartments of the marine environment including biota such as seafood; ingestion from such sources is one of the two major uptake routes identified for human exposure.Objectives: The objectives were to conduct a systematic review and meta-analysis of the levels of MP contamination in seafood, and to subsequently estimate the annual human uptake.Methods: MEDLINE, EMBASE and Web of Science were searched from launch (1947, 1974 and 1900, respectively) up to October 2020 for all studies reporting MP content in seafood species. Mean, standard deviations (SD) and ranges of MPs found were collated. Studies were appraised systematically using a bespoke Risk of Bias (RoB) assessment tool.Results: Fifty studies were included in the systematic review and 19 in the meta-analysis. Evidence was available on four phyla; molluscs, crustaceans, fish and echinodermata. The majority of studies identified MP contamination in seafood and reported MP content below 1MPs/g (microplastics per gram), with 26% of studies rated as having high RoB, mainly due to analysis or reporting weaknesses. Molluscs collected off the coasts of Asia were the most heavily contaminated, coinciding withreported trends of MP contamination in the sea. According to the statistical summary, MP content was 0-10.5 MPs/g in molluscs, 0.1-8.6 MPs/g in crustaceans, 0-2.9 MPs/g in fish and 1MPs/g in echinodermata. Maximum annual human MP uptake was estimated to be close to 55,000 MP particles. Statistical, sample and methodological heterogeneity was high.Discussion: This is the first systematic review, to our knowledge, to assess and quantify MP contamination of seafood and human uptake from its consumption, suggesting that action must be considered in order to reduce human exposure via such consumption. Further high-quality research using standardized methods is needed to cement the scientific evidence on MP contamination and human exposures

Microplastic contamination of salt intended for human consumption: a systematic review and meta-analysis

Microplastics (MPs) are an emerging contaminant ubiquitous in the environment. There is growing concern regarding potential human health effects, a major human exposure route being dietary uptake. We have undertaken a systematic review (SR) and meta-analysis to identify all relevant research on MP contamination of salt intended for human consumption. Three thousand nine hundred and nineteen papers were identified, with ten fitting the inclusion criteria. A search of the databases MEDLINE, EMBASE and Web of Science, from launch date to September 2020, was conducted. MP contamination of salt varied significantly between four origins, sea salt 0–1674 MPs/kg, lake salt 8–462 MPs/kg, rock and well salt 0–204 MPs/kg. The majority of samples were found to be contaminated by MPs. Corresponding potential human exposures are estimated to be 0–6110 MPs per year (for all origins), confirming salt as a carrier of MPs. A bespoke risk of bias (RoB) assessment tool was used to appraise the quality of the studies, with studies demonstrating moderate to low RoB. These results suggest that a series of recurring issues need to be addressed in future research regarding sampling, analysis and reporting to improve confidence in research findings

Intersex related gene expression profiles in clams Scrobicularia plana : molecular markers and environmental application

Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction

PVC Does Not Influence Cadmium Uptake or Effects in the Mussel (Mytilus edulis)

Microplastics have become a global concern in recent years. In this study, we studied (i) whether the presence of polyvinyl chloride (PVC) microparticles may affect cadmium (Cd) uptake in mussel (Mytilus edulis); and (ii) the biological effects of PVC microparticles exposure alone or in combination with Cd. Significant Cd uptake in digestive gland was observed following Cd exposure. However, PVC did not significantly increase Cd uptake compared with Cd alone treatment. In terms of biological impacts, significantly lower neutral red retention (NRR) time and elevated expression of Metallothionein isoform 20-IV (MT-20) were observed in mussels exposed to Cd alone, or combined with microplastics, yet there was no significant difference between them. catalase (CAT) expression only showed a significant increase in mussels exposed to Cd alone. This work provides an insight into the relationship on resulting biological impacts between these two contaminants

The role of ras gene in the development of haemic neoplasia in Mytilus trossulus

Disseminated neoplasia has been reported in mussels (Mytilus spp) from numerous locations worldwide. This condition is progressive and fatal and the aetiology is unknown. In vertebrates, oncogenes such as ras, and tumour suppressor genes such as p53, play important roles in carcinogenesis. We have cloned a Mytilus trossulus homologue of the vertebrate ras gene, which shows conserved sequence in regions of functional importance. Neoplastic hemolymph samples derived from M. trossulus have been investigated for the presence of ras gene mutations and changes in expression

Hepatocellular adenoma in a European flatfish (Limanda limanda) : genetic alterations in laser-capture microdissected tissue and global transcriptomic approach

Liver tumours in flatfish have been diagnosed using histopathology for decades to monitor the impacts of marine pollution. Here we describe the application of specific gene (retinoblastoma, Rb) profiling in laser capture micro-dissected samples, and a suppression subtractive hybridization (SSH) approach to isolate differentially expressed genes in hepatocellular adenoma (HCA) samples from dab, Limanda limanda. The Rb profiles from apparently normal and HCA micro-dissected samples of fish from the North Sea showed no significant difference, and genotypic heterogeneity within defined histological phenotypes was observed. In the SSH, sequences associated with cell signalling, cell cycle, gene expression regulation, protein transport and protein degradation were isolated. These included up-regulation of arrestin domain containing 3 (arrdc3), Rac-1 and tribbles, and down-regulation of ankyrin repeat/sterile alpha-motif domain-containing protein 1B-like (ANKS1B-like), c-fos, CDKN1B and RhoA-like sequences, previously implicated in mammalian HCA. This study offers new candidates involved in fish liver tumour development