Minimizing Shear Stress in Cell Signaling Studies.

Cellular signal transduction comprises a complex series of biochemical reactions by which extracellular signals such as growth factors, hormones, cytokines, and neurotransmitters are translated into specific intracellular responses. Signal transduction is mediated by protein kinase phosphorylation cascades that culminate in the regulation of numerous cellular responses, including division, differentiation, migration, and survival. Importantly, signal relay pathways are dysregulated in human diseases, making the study of signal transduction important for both uncovering basic biology and understanding pathophysiology. Established laboratory cell culture models are useful for studying signal transduction mechanisms, but differences in sample handling procedures can introduce unwanted variability in experimental outcomes and conclusions. One such potential source of experimental variability is the introduction of fluid shear stress upon handling of tissue culture cells. Fluid shear stress triggers a wide range of cellular responses in adherent cell culture, including stimulating the production of cyclic AMP, potentiating the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), and ultimately inducing changes in the gene expression of growth and remodeling factors. Further, mechanical stress on cells is physiologically relevant to the development of many pathologies. Here, we describe a detailed protocol for cell lysis and protein extraction that minimizes shear stress induced by classical cell harvest protocols. We also highlight the impact of fluid shear stress by using immunoblotting to assess ERK pathway activation as a readout for this protocol. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Gentle cell lysis and protein extraction Basic Protocol 2: Immunoblotting for cell signaling readouts by SDS-PAGE.

PRO-Act: a healthcare provider workshop outlining the added value of implementing PROs in routine HIV practice.

Patient Reported Outcomes (PROs) are an evidenced way of adding value to routine clinical care. As a source of unique information on the effect of a medical condition and its treatment from the patients' perspective (Mercieca-Bebber et al. in Patient Relat Outcome Meas 9: 353-367, https://doi.org/10.2147/PROM.S156279 , 2018), PROs allow for an improved assessment in routine clinical care of symptoms, side effects, functional outcomes (physical, sexual, social, emotional, cognitive functioning), and health-related quality of life (HRQoL). By helping to align healthcare providers' interventions with what matters most to the patient, PROs contribute to the individualized choice of Anti-Retroviral Therapy (Carfora et al. in PLoS ONE 17(4): e0267030, https://doi.org/10.1371/journal.pone.0267030 , 2022) as a paramount component of tailored and person-centred care management, in routine clinical practice. This article outlines a practical framework and process tested in Portugal to raise awareness of PROs' added value, and to help guide first steps in the implementation and seamless integration of PROs, in routine HIV care.

Experiences of parents of children with hypoplastic left heart syndrome during their treatment: a qualitative study.

AIM: To investigate the opinion and personal experience of parents of children born with Hypoplastic Left Heart Syndrome and what advice they would give to other parents who have to decide between treatment options. METHODS: We conducted a qualitative, descriptive and retrospective study by means of a survey directed to parents of children born with Hypoplastic Left Heart Syndrome in a tertiary hospital in Buenos Aires (Argentina). Their answers and data regarding medical procedures were analysed. RESULTS: Parents of thirteen out of sixteen patients with Hypoplastic Left Heart Syndrome were surveyed. Norwood surgery had been performed in all the patients, many had received other procedures, and five had died. In relation to the decision-making process, sixty-one percent of parents would recommend other parents to remain at peace after having done everything possible and 54% would suggest to not feel guilt despite the final result. None of the parents would recommend rejecting surgical treatment and choosing comfort care. CONCLUSION: The majority of parents of children with Hypoplastic Left Heart Syndrome would recommend continuing with the therapeutic effort in order to feel at peace and reduce feelings of guilt.

Tratamiento de reposición enzimática en la insuficiencia pancreática exocrina asociada a la fibrosis quística. Grupo de trabajo de Fibrosis Quística de la Sociedad Latinoamericana de Gastroenterología, Hepatología y Nutrición Pediátrica (LASPHGAN) / Enzyme replacement treatment in exocrine pancreatic insufficiency associated with cystic fibrosis. Cystic fibrosis Working group of the Latin American Society of Pediatric Gastroenterology, Hepatology and Nutrition (LASPHGAN)

La fibrosis quística (FQ) es un trastorno hereditario, de las glándulas de secreción exocrina, considerada la causa más frecuente de insuficiencia pancreática exocrina (IPE) en la infancia. Esta revisión resume el panorama del tratamiento de reposición enzimática en la IPE asociada a la FQ, las formulaciones disponibles, su dosificación y modo de administración, así como las limitaciones y desafíos actuales y las posibles áreas del desarrollo futuro

Cystic fibrosis (CF) is an inherited disorder of the exocrine secretion glands, considered the most frequent cause of exocrine pancreatic insufficiency (EPI) in childhood. This review summarizes the landscape of enzyme replacement therapy in PEI associated with CF, the available formulations, their dosage and mode of administration, as well as the current limitations and challenges and potential areas for future development.

Relationship between structure and cytotoxicity of vanadium and molybdenum complexes with pyridoxal derived ligands.

In this work four vanadium complexes (compounds 1, 2, 3 and 4) and one molybdenum complex (compound 5) with hydrazone ligands derived from pyridoxal were synthesized and characterized. All compounds are mononuclear species, two of them (compounds 3 and 5) are dioxide complexes and the other three (compounds 1, 2 and 4) monoxide complexes. The vanadium atom of the compound 3 is five-coordinated and all the other compounds have a six coordinated environment polyhedron. The poses for the potential intercalation of the compounds 2 and 3 with DNA were obtained by using AutoDock software. Optimizations were also performed at PM6-D3H4 semi-empirical level whereas the study of the nature of the interaction was carried out by means of the Energy Decomposition Analysis and the Non-Covalent Interaction index by using in both cases Density Functional Theory computations. The cytotoxicity in lung cancer cells (A549 cell line) of all the compounds was also evaluated. After 24 h of treatment, vanadium complexes showed high values of IC50, between 419.93 ± 22.58 and 685.88 ± 46.55 µM. After 48 h, the results showed that the compound 3 had the lowest IC50 value, 65.32 ± 9.95 µM, and the compound 2 the highest value, 375.28 ± 32.09 µM. The molybdenum complex showed the lowest IC50 value at 48 h (11.22 ± 1.34 µM). The toxicity of the compounds 3, 4 and 5 was tested in vivo, using zebrafish model, and the molybdenum complex showed higher toxic effects than the studied vanadium complexes.

Real-World Characterization of the Portuguese Population Living with HIV who Initiated Raltegravir Based-Regimens: The REALITY Study.

INTRODUCTION: Although raltegravir has been available since 2007, data are lacking on the Portuguese population living with HIV who initiated this antiretroviral therapy. Hence, this study aimed to characterize the patients who initiated raltegravir-based regimens between January 2015 and December 2017, on sociodemographics, clinical features, and treatment satisfaction. MATERIAL AND METHODS: Observational, retrospective, multicentre study conducted at 11 reference sites. Sociodemographic and clinical data were collected retrospectively from hospital medical records. For participants continuing raltegravir at study inclusion, the HIV Treatment Satisfaction Questionnaire was administered to assess satisfaction with raltegravir-based therapy. Descriptive statistics were performed. Treatment-naïve and treatment-experienced subgroups were compared for demographic and clinical variables. RESULTS: A total of 302 patients were included; mostly men (69.5%) with a mean age of 49 years old. Approximately half of the patients had at least one non-AIDS-related comorbidity at baseline (53.3%), such as hypercholesterolemia, arterial hypertension, diabetes mellitus, and depression. Moreover, 52.3% were treatment-experienced patients with up to two treatments prior to raltegravir. Across the study time points, there was a reduction in the viral load and improvement in CD4 counts in both the treatment-naïve and treatment-experienced subgroups. Continuing users of raltegravir reported high treatment satisfaction (55.4 ± 7.2 points). CONCLUSION: Raltegravir-based regimens seem like a valid therapeutic option in heterogeneous populations of HIV-infected patients, in patients with previous ART experience and as part of first-line therapeutic options alongside with the latest generation of drugs from its class.

Introdução: Apesar de o raltegravir estar disponível desde 2007, os dados na população portuguesa com VIH que iniciou esta terapêutica antirretroviral são escassos. Deste modo, este estudo teve por objetivo caracterizar os doentes que iniciaram um regime terapêutico baseado em raltegravir entre janeiro de 2015 e dezembro de 2017, relativamente a dados sociodemográficos, características clínicas e satisfação com o tratamento. Material e Métodos: Estudo observacional, retrospetivo, multicêntrico conduzido em 11 centros de referência. Os dados sociodemográficos e clínicos foram recolhidos retrospetivamente nos processos clínicos. Os participantes que continuaram o regime com raltegravir após a inclusão no estudo preencheram o HIV Treatment Satisfaction Questionnaire para avaliar a satisfação com a terapêutica. Foram efetuadas análises de estatística descritiva e comparações para as variáveis sociodemográficas e clínicas nos subgrupos de doentes naïve de tratamento e de doentes com experiência terapêutica. Resultados: Foram incluídos 302 doentes, maioritariamente do sexo masculino (69,5%) com idade média de 49 anos. Aproximadamente metade dos doentes tinha pelo menos uma comorbilidade não relacionada com SIDA no início do estudo (53,3%), tais como hipercolesterolemia, hipertensão arterial, diabetes mellitus ou depressão. Adicionalmente, 52,3% eram doentes com experiência terapêutica com até dois tratamentos anteriores ao raltegravir. Ao longo do estudo verificou-se uma redução na carga viral e uma melhoria nas contagens de CD4 em ambos os subgrupos de doentes (doentes naïve de tratamento e doentes com experiência terapêutica). Os doentes com uso continuado de raltegravir reportaram uma elevada satisfação com o tratamento (55,4 ± 7,2 pontos). Conclusão: Os regimes terapêuticos baseados em raltegravir parecem ser uma opção terapêutica válida em populações heterogéneas de doentes infetados com VIH, em doentes com experiência em ART e como tratamento de primeira linha, em paralelo com outras terapêuticas de última geração.

H3.1K27me1 maintains transcriptional silencing and genome stability by preventing GCN5-mediated histone acetylation.

Epigenetic mechanisms play diverse roles in the regulation of genome stability in eukaryotes. In Arabidopsis thaliana, genome stability is maintained during DNA replication by the H3.1K27 methyltransferases ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6, which catalyze the deposition of K27me1 on replication-dependent H3.1 variants. The loss of H3.1K27me1 in atxr5 atxr6 double mutants leads to heterochromatin defects, including transcriptional de-repression and genomic instability, but the molecular mechanisms involved remain largely unknown. In this study, we identified the transcriptional co-activator and conserved histone acetyltransferase GCN5 as a mediator of transcriptional de-repression and genomic instability in the absence of H3.1K27me1. GCN5 is part of a SAGA-like complex in plants that requires the GCN5-interacting protein ADA2b and the chromatin remodeler CHR6 to mediate the heterochromatic defects in atxr5 atxr6 mutants. Our results also indicate that Arabidopsis GCN5 acetylates multiple lysine residues on H3.1 variants, but H3.1K27 and H3.1K36 play essential functions in inducing genomic instability in the absence of H3.1K27me1. Finally, we show that H3.1K36 acetylation by GCN5 is negatively regulated by H3.1K27me1 in vitro. Overall, this work reveals a key molecular role for H3.1K27me1 in maintaining transcriptional silencing and genome stability in heterochromatin by restricting GCN5-mediated histone acetylation in plants.

Genetic variability in Ruditapes decussatus clam combined with Perkinsus infection level to support founder population selection for a breeding program.

Clam farmers worldwide face several challenges, including irregular seed supply and high mortalities due to pathogenic organisms such as Perkinsus olseni. In Europe, there is a high unmet consumer demand for native clam species such as Ruditapes decussatus. The high market value of R. decussatus makes the culture of this species potentially more attractive than that culture of the alien species Ruditapes philippinarum. Thus, there is a market opportunity in breeding and producing R. decussatus at an industrial scale. A selective breeding program to improve R. decussatus performance will be carried out in Portugal; and the first critical step to develop such a breeding program is the establishment of a founder population. In this study, intra- and interpopulation genetic diversity was assessed using 13 microsatellite markers in eight natural beds located in Portugal, Spain and Italy. Also, allele and genotypic frequencies of each microsatellite locus were assessed discriminating between clams infected and non-infected by P. olseni. All locations showed similar values for several genetic diversity parameters. Analyses of population differentiation (F ST, Bayesian clustering and AMOVAs) revealed five genetically differentiated regions: Rías Altas and Rías Baixas (NW Spain), North/Central Coast of Portugal, Gulf of Cadiz and Adriatic Sea. Significant differences in the allelic and genotypic frequency distribution between infected clams and non-infected ones at four microsatellite loci are reported suggesting that resistance to the disease could have a genetic basis. Moreover, a positive or negative relationship between the frequency of certain alleles and the parasite infection was inferred. Further studies should confirm the potential use of those alleles as genetic markers for P. olseni infection. Integrating results of genetic diversity within and between populations and Perkinsus infection levels, a founder population for a R. decussatus breeding program is proposed, composed by individuals from Barallobre (Rías Altas), Pontevedra or Cangas (Rías Baixas), Óbidos (North/Central Coast of Portugal), Algarve (Gulf of Cadiz) and Venice (Adriatic Sea).

Oral ulcer as presentation of cavitating pulmonary tuberculosis.

Tuberculosis is an indolent infection that can invade any organ. Although the most frequent form of presentation is pulmonary, it can have an extra-pulmonary presentation, including rare cases of oral tuberculosis. We present a clinical case of a 44 year-old man, active smoker, with an ulcerated lesion on the posterior third of the tongue, initially interpreted as a probable neoplasm. The pathological study of the biopsy performed on the lesion, showed alterations compatible with a chronic granulomatous process and the presence of acid-fast bacilli. The concomitant diagnosis of pulmonary tuberculosis was made in a subsequent study. The patient started therapy with isoniazid, rifampin, pyrazinamide and ethambutol with complete resolution of the oral lesion and pulmonary tuberculosis. This case exemplifies the importance of including tuberculosis in the differential diagnosis of ulcerated and neoformative lesions and the value of performing a microbiological study alongside the pathological one.

Chronic hepatitis C treatment in HIV co-infection in Portugal: Results from a cohort OF 2133 patients presented by GEPCOI (Portuguese Coinfection Study Group).

Direct-acting antiviral drugs (DAAs) have recently changed the paradigm of hepatitis C therapy, significantly improving treatment response rates, patient life expectancy and quality of life. In Portugal, sofosbuvir (SOF) and SOF/ledipasvir (SOF/LDV) were fully reimbursed by the National Health System since early 2015 and generalized use of interferon-free DAA based regimens became current practice. During 2016, the remaining DAAs were sequentially added and covered by the same health access policy. The Portuguese Study Group of Hepatitis and HIV Co-infection (GEPCOI) collected data from 15 clinical centres in Portugal, pertaining to the HCV treatment experience with DAA regimens. A cohort of 2133 patients was analysed, representing one of the largest DAA treated HCV/HIV co-infected individuals. The global sustained virologic response (SVR) achieved was 95% in this real-life cohort setting. Linear regression analysis showed significant differences in treatment response rates when using SOF plus ribavirin (RBV) combination in genotype 2 or 3 infected individuals (P < .002) and in those with liver cirrhosis (P < .002). These findings corroborate that early treatment is mandatory in HIV/HCV co-infected patients, as response rates may be negatively influenced by higher fibrosis stages and suboptimal DAA regimens. The current national Portuguese health policy should continue to promote wider treatment access and individualized therapy strategies, aiming at the elimination of HCV infection in this high-risk co-infected population.

RNA-Seq Analysis for Assessing the Early Response to DSP Toxins in Mytilus galloprovincialis Digestive Gland and Gill.

The harmful effects of diarrhetic shellfish poisoning (DSP) toxins on mammalian cell lines have been widely assessed. Studies in bivalves suggest that mussels display a resistance to the cytogenotoxic effects of DSP toxins. Further, it seems that the bigger the exposure, the more resistant mussels become. To elucidate the early genetic response of mussels against these toxins, the digestive gland and the gill transcriptomes of Mytilus galloprovincialis after Prorocentrum lima exposure (100,000 cells/L, 48 h) were de novo assembled based on the sequencing of 8 cDNA libraries obtained using an Illumina HiSeq 2000 platform. The assembly provided 95,702 contigs. A total of 2286 and 4523 differentially expressed transcripts were obtained in the digestive gland and the gill, respectively, indicating tissue-specific transcriptome responses. These transcripts were annotated and functionally enriched, showing 44 and 60 significant Pfam families in the digestive gland and the gill, respectively. Quantitative PCR (qPCR) was performed to validate the differential expression patterns of several genes related to lipid and carbohydrate metabolism, energy production, genome integrity and defense, suggesting their participation in the protective mechanism. This work provides knowledge of the early response against DSP toxins in the mussel M. galloprovincialis and useful information for further research on the molecular mechanisms of the bivalve resistance to these toxins.

Sequence characterization of the 5S ribosomal DNA and the internal transcribed spacer (ITS) region in four European Donax species (Bivalvia: Donacidae).

BACKGROUND: The whole repeat unit of 5S rDNA and the internal transcribed spacer (ITS) of four European Donax species were analysed. After amplifying, cloning and sequencing several 5S and ITS units, their basic features and their variation were described. The phylogenetic usefulness of 5S and ITS sequences in the inference of evolutionary relationships among these wedge clams was also investigated. RESULTS: The length of the 5S repeat presented little variation among species, except D. trunculus that differed from the rest of the Donax species in 170-210 bp. The deduced coding region covered 120 bp, and showed recognizable internal control regions (ICRs) involved in the transcription. The length of non-transcribed spacer region (NTS) ranged from 157 bp to 165 bp in Donax trunculus and from 335 bp to 367 bp in the other three species. The conservation degree of transcriptional regulatory regions was analysed revealing a conserved TATA-like box in the upstream region. Regarding ITS sequences, the four Donax species showed slight size differences among clones due to the variation occurring in the ITS1 and ITS2, except Donax variegatus did not display size differences in the ITS2. The total length of the ITS sequence ranged between 814 and 1014 bp. Resulting phylogenetic trees display that the two ribosomal DNA regions provide well-resolved phylogenies where the four European Donax species form a single clade receiving high support in nodes. The topology obtained with 5S sequences was in agreement with Donax evolutionary relationships inferred from several sequences of different nature in previous studies. CONCLUSIONS: This is not only a basic research work, where new data and new knowledge is provided about Donax species, but also have allowed the authentication of these wedge clams and offers future applications to provide other genetic resources.

Cytomegalovirus acute infection with pulmonary involvement in an immunocompetent patient.

Introduction: Cytomegalovirus (CMV) infection in healthy adults is usually asymptomatic or causes a mild mononucleosis syndrome, while severe infections are rare in immunocompetent patients and poorly documented. When described, gastrointestinal tract and the central nervous systems are the most frequent sites of severe CMV infection. Lung disease can occur, but it's rare. Clinical case: A 29 years old man presenting with a 2-weeks history of fever, headache, malaise, dry non-productive cough and thoracic pleuritic pain, without improvement after one-week therapy with levofloxacin. Blood exams showed lymphocytosis of almost 50%, nine percent of atypical lymphocytes and elevated transaminases. Thoracic CT-scan showed bilateral infiltrate with internal air bronchogram. Blood serology showed positivity for CMV IgG and IgM, with low CMV IgG avidity. Serum and bronchoalveolar detection of CMV by polymerase chain reaction (PCR) technique was also positive. Cultures were all negative. The patient became increasingly hypoxemic and the liver transaminases worsening, the reason for which ganciclovir was started. He made a full recovery and was discharged seven days later with oral valganciclovir, completing a 3 weeks antiviral course at home. Discussion: CMV pneumonia is a rare condition, however it's one of the three most common cause of severe viral community acquired pneumonia (CAP), along with influenza and adenovirus. CMV pneumonia should be considered in patients with atypical lymphocytes and mildly elevated serum transaminases. Conclusion: In immunocompetent hosts, even with severe CMV-CAP, the prognosis is good. However, antiviral treatment should be considered in the rare occasion of severe CMV infection. Nevertheless, more studies are needed to clarify the clinical benefit of antiviral treatment.

Increased efficiency of targeted mutagenesis by CRISPR/Cas9 in plants using heat stress.

The CRISPR/Cas9 system has greatly improved our ability to engineer targeted mutations in eukaryotic genomes. While CRISPR/Cas9 appears to work universally, the efficiency of targeted mutagenesis and the adverse generation of off-target mutations vary greatly between different organisms. In this study, we report that Arabidopsis plants subjected to heat stress at 37°C show much higher frequencies of CRISPR-induced mutations compared to plants grown continuously at the standard temperature (22°C). Using quantitative assays relying on green fluorescent protein (GFP) reporter genes, we found that targeted mutagenesis by CRISPR/Cas9 in Arabidopsis is increased by approximately 5-fold in somatic tissues and up to 100-fold in the germline upon heat treatment. This effect of temperature on the mutation rate is not limited to Arabidopsis, as we observed a similar increase in targeted mutations by CRISPR/Cas9 in Citrus plants exposed to heat stress at 37°C. In vitro assays demonstrate that Cas9 from Streptococcus pyogenes (SpCas9) is more active in creating double-stranded DNA breaks at 37°C than at 22°C, thus indicating a potential contributing mechanism for the in vivo effect of temperature on CRISPR/Cas9. This study reveals the importance of temperature in modulating SpCas9 activity in eukaryotes, and provides a simple method to increase on-target mutagenesis in plants using CRISPR/Cas9.

First complete female mitochondrial genome in four bivalve species genus Donax and their phylogenetic relationships within the Veneroida order.

BACKGROUND: Four species of the genus Donax (D. semistriatus, D. trunculus, D. variegatus and D. vittatus) are common on Iberian Peninsula coasts. Nevertheless, despite their economic importance and overexploitation, scarce genetic resources are available. In this work, we newly determined the complete mitochondrial genomes of these four representatives of the family Donacidae, with the aim of contributing to unveil phylogenetic relationships within the Veneroida order, and of developing genetic markers being useful in wedge clam identification and authentication, and aquaculture stock management. PRINCIPAL FINDINGS: The complete female mitochondrial genomes of the four species vary in size from 17,044 to 17,365 bp, and encode 13 protein-coding genes (including the atp8 gene), 2 rRNAs and 22 tRNAs, all located on the same strand. A long non-coding region was identified in each of the four Donax species between cob and cox2 genes, presumably corresponding to the Control Region. The Bayesian and Maximum Likelihood phylogenetic analysis of the Veneroida order indicate that all four species of Donax form a single clade as a sister group of other bivalves within the Tellinoidea superfamily. However, although Tellinoidea is actually monophyletic, none of its families are monophyletic. CONCLUSIONS: Sequencing of complete mitochondrial genomes provides highly valuable information to establish the phylogenetic relationships within the Veneroida order. Furthermore, we provide here significant genetic resources for further research and conservation of this commercially important fishing resource.

Characterization of mussel H2A.Z.2: a new H2A.Z variant preferentially expressed in germinal tissues from Mytilus.

Histones are the fundamental constituents of the eukaryotic chromatin, facilitating the physical organization of DNA in chromosomes and participating in the regulation of its metabolism. The H2A family displays the largest number of variants among core histones, including the renowned H2A.X, macroH2A, H2A.B (Bbd), and H2A.Z. This latter variant is especially interesting because of its regulatory role and its differentiation into 2 functionally divergent variants (H2A.Z.1 and H2A.Z.2), further specializing the structure and function of vertebrate chromatin. In the present work we describe, for the first time, the presence of a second H2A.Z variant (H2A.Z.2) in the genome of a non-vertebrate animal, the mussel Mytilus. The molecular and evolutionary characterization of mussel H2A.Z.1 and H2A.Z.2 histones is consistent with their functional specialization, supported on sequence divergence at promoter and coding regions as well as on varying gene expression patterns. More precisely, the expression of H2A.Z.2 transcripts in gonadal tissue and its potential upregulation in response to genotoxic stress might be mirroring the specialization of this variant in DNA repair. Overall, the findings presented in this work complement recent reports describing the widespread presence of other histone variants across eukaryotes, supporting an ancestral origin and conserved role for histone variants in chromatin.

Early Genotoxic and Cytotoxic Effects of the Toxic Dinoflagellate Prorocentrum lima in the Mussel Mytilus galloprovincialis.

Okadaic acid (OA) and dinophysistoxins (DTXs) are the main toxins responsible for diarrhetic shellfish poisoning (DSP) intoxications during harmful algal blooms (HABs). Although the genotoxic and cytotoxic responses to OA have been evaluated in vitro, the in vivo effects of these toxins have not yet been fully explored. The present work fills this gap by evaluating the in vivo effects of the exposure to the DSP-toxin-producing dinoflagellate Prorocentrum lima during the simulation of an early HAB episode in the mussel Mytilus galloprovincialis. The obtained results revealed that in vivo exposure to this toxic microalgae induced early genotoxicity in hemocytes, as a consequence of oxidative DNA damage. In addition, the DNA damage observed in gill cells seems to be mainly influenced by exposure time and P. lima concentration, similarly to the case of the oxidative damage found in hemocytes exposed in vitro to OA. In both cell types, the absence of DNA damage at low toxin concentrations is consistent with the notion suggesting that this level of toxicity does not disturb the antioxidant balance. Lastly, in vivo exposure to growing P. lima cell densities increased apoptosis but not necrosis, probably due to the presence of a high number of protein apoptosis inhibitors in molluscs. Overall, this work sheds light into the in vivo genotoxic and cytotoxic effects of P. lima. In doing so, it also demonstrates for the first time the potential of the modified (OGG1) comet assay for assessing oxidative DNA damage caused by marine toxins in marine invertebrates.

Unbiased high-throughput characterization of mussel transcriptomic responses to sublethal concentrations of the biotoxin okadaic acid.

Background. Harmful Algal Blooms (HABs) responsible for Diarrhetic Shellfish Poisoning (DSP) represent a major threat for human consumers of shellfish. The biotoxin Okadaic Acid (OA), a well-known phosphatase inhibitor and tumor promoter, is the primary cause of acute DSP intoxications. Although several studies have described the molecular effects of high OA concentrations on sentinel organisms (e.g., bivalve molluscs), the effect of prolonged exposures to low (sublethal) OA concentrations is still unknown. In order to fill this gap, this work combines Next-Generation sequencing and custom-made microarray technologies to develop an unbiased characterization of the transcriptomic response of mussels during early stages of a DSP bloom. Methods. Mussel specimens were exposed to a HAB episode simulating an early stage DSP bloom (200 cells/L of the dinoflagellate Prorocentrum lima for 24 h). The unbiased characterization of the transcriptomic responses triggered by OA was carried out using two complementary methods of cDNA library preparation: normalized and Suppression Subtractive Hybridization (SSH). Libraries were sequenced and read datasets were mapped to Gene Ontology and KEGG databases. A custom-made oligonucleotide microarray was developed based on these data, completing the expression analysis of digestive gland and gill tissues. Results. Our findings show that exposure to sublethal concentrations of OA is enough to induce gene expression modifications in the mussel Mytilus. Transcriptomic analyses revealed an increase in proteasomal activity, molecular transport, cell cycle regulation, energy production and immune activity in mussels. Oppositely, a number of transcripts hypothesized to be responsive to OA (notably the Serine/Threonine phosphatases PP1 and PP2A) failed to show substantial modifications. Both digestive gland and gill tissues responded similarly to OA, although expression modifications were more dramatic in the former, supporting the choice of this tissue for future biomonitoring studies. Discussion. Exposure to OA concentrations within legal limits for safe consumption of shellfish is enough to disrupt important cellular processes in mussels, eliciting sharp transcriptional changes as a result. By combining the study of cDNA libraries and a custom-made OA-specific microarray, our work provides a comprehensive characterization of the OA-specific transcriptome, improving the accuracy of the analysis of expresion profiles compared to single-replicated RNA-seq methods. The combination of our data with related studies helps understanding the molecular mechanisms underlying molecular responses to DSP episodes in marine organisms, providing useful information to develop a new generation of tools for the monitoring of OA pollution.

In Vitro Analysis of Early Genotoxic and Cytotoxic Effects of Okadaic Acid in Different Cell Types of the Mussel Mytilus galloprovincialis.

Okadaic acid (OA) is the predominant biotoxin responsible for diarrhetic shellfish poisoning (DSP) syndrome in humans. While its harmful effects have been extensively studied in mammalian cell lines, the impact on marine organisms routinely exposed to OA is still not fully known. Few investigations available on bivalve molluscs suggest less genotoxic and cytotoxic effects of OA at high concentrations during long exposure times. In contrast, no apparent information is available on how sublethal concentrations of OA affect these organisms over short exposure times. In order to fill this gap, this study addressed for the first time in vitro analysis of early genotoxic and cytotoxic effects attributed to OA in two cell types of the mussel Mytilus galloprovincialis. Accordingly, hemocytes and gill cells were exposed to low OA concentrations (10, 50, 100, 200, or 500 nM) for short periods of time (1 or 2 h). The resulting DNA damage, as apoptosis and necrosis, was subsequently quantified using the comet assay and flow cytometry, respectively. Data demonstrated that (1) mussel hemocytes seem to display a resistance mechanism against early genotoxic and cytotoxic OA-induced effects, (2) mussel gill cells display higher sensitivity to early OA-mediated genotoxicity than hemocytes, and (3) mussel gill cells constitute more suitable systems to evaluate the genotoxic effect of low OA concentrations in short exposure studies. Taken together, this investigation provides evidence supporting the more reliable suitability of mussel gill cells compared to hemocytes to evaluate the genotoxic effect of low short-duration exposure to OA.

Characterization of nineteen microsatellite markers and development of multiplex PCRs for the wedge clam Donax trunculus (Mollusca: Bivalvia).

The wedge clam Donax trunculus is an Atlantic-Mediterranean warm-temperate species found from Senegal to the northern coast of France, including the Mediterranean and Black Sea. It is commercially exploited in several European countries and constitutes an important fishing resource due to its high economical value. To contribute to its conservation and management, nineteen microsatellite markers were isolated from two enriched genomic libraries. These loci were characterized in 30 clams from a single population from northwest Spain. The number of alleles per locus ranged from 2 to 17 and observed and expected heterozygosity varied from zero to 0.714 and from 0.078 to 0.950, respectively. Linkage disequilibrium was not detected and nine loci were in agreement with Hardy-Weinberg equilibrium. Fifteen polymorphic markers were arranged into three multiplex PCR sets to reduce both time and cost of microsatellite genotyping. This is the first time that polymorphic microsatellite markers have been reported for D. trunculus. These new markers provide a valuable resource for future population genetics studies and management and culture of this species.