First description of the fish-killing raphidophyceae Chattonella marina complex in Argentina: From genetics to ichthyotoxicity unveiled.

Species of the harmful algal bloom (HAB)-forming genus Chattonella (Raphidophyceae) are responsible for massive fish kills worldwide. Despite this, the genus remains still unexplored in Argentinean waters in the Southwestern Atlantic. Three Chattonella strains (LPCc045, LPCc046, and LPCc047) were isolated and cultured as part of a harmful phytoplankton monitoring program in the marine coastal waters of Buenos Aires Province to determine: 1) taxonomic and genetic identification, 2) pigment compositions, and 3) ichthyotoxic potency and ROS production.

Allelopathic Effect of a Chilean Strain of (Gymnodiniales, Dinoflagellata) on Phytoplankton Species.

Blooms of the dinoflagellate in Chile, often associated with massive fish kills, have been noted alongside other species from the Kareniaceae family, such as spp. and spp. However, the potential allelopathy impact of Chilean on other phytoplankton species remains unexplored.

Identification of bacteria in potential mutualism with toxic Alexandrium catenella in Chilean Patagonian fjords by in vitro and field monitoring.

The dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms, repeatedly causing damage to Chilean coastal waters. The causes and behavior of algal blooms are complex and vary across different regions. As bacterial interactions with algal species are increasingly recognized as a key factor driving algal blooms, the present study identifies several bacterial candidates potentially associated with Chilean Alexandrium catenella.

Evidence of plastic pollution from offshore oceanic sources in southern Chilean Patagonian fjords.

The Chilean Patagonian fjords are globally renowned as one of the few remaining pristine environments on Earth; however, their ecosystems are under significant threat from climatic and anthropogenic pressures. Of particular concern is the lack of research into the impact of plastic pollution on the waters and biodiversity of these fjords. In this study, the marine environment of a secluded and sparsely populated fjord system in southern Patagonia was sampled to assess microplastics in seawater, beaches, bottom sediment, and zooplankton.

Emerging phycotoxins in the Chilean coast: First localized detection of the neurotoxic cyclic imine Pinnatoxin-G in shellfish banks.

Pinnatoxins (PnTXs) produced by the cosmopolitan dinoflagellate Vulcanodinium rugosum are highly potent cyclic imines that represent a risk for seafood consumers, artisanal fisheries, and the local aquaculture industry. Among the eight known PnTXs, pinnatoxin-G (PnTX-G) is the most frequent toxin analog detected in shellfish. Despite PnTX-G is still not internationally regulated, the French Agency for Food, Environmental and Occupational Health and Safety established that a risk for human consumers may exist when the accumulation of PnTX-G in shellfish exceeds 23 μg kg.

Mitigation of Marine Dinoflagellates Using Hydrogen Peroxide (HO) Increases Toxicity towards Epithelial Gill Cells.

Hydrogen peroxide (HO) has been shown to efficiently remove toxic microalgae from enclosed ballast waters and brackish lakes. In this study, in vitro experiments were conducted to assess the side effects of mitigating toxic and non-toxic dinoflagellates with HO. Five HO concentrations (50 to 1000 ppm) were used to control the cell abundances of the toxic dinoflagellates and and the non-toxic dinoflagellates and Photosynthetic efficiency and staining dye measurements showed the high efficiency of HO for mitigating all dinoflagellate species at only 50 ppm.

in Patagonian Fjords: Genetics, Growth, Pigment Signature and Role of PUFA and ROS in Ichthyotoxicity.

Heterosigma akashiwo is the only raphidophyte described for Chilean waters. A recent 2021 fish-killing bloom event of this raphidophyte ignited scientific research, but the ichthyotoxic mechanism and environmental conditions that promote its growth are still unclear. This is the first study confirming the occurrence of H.

The effect of iron on Chilean Alexandrium catenella growth and paralytic shellfish toxin production as related to algal blooms.

The dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms (HABs) worldwide. Blooms of this species have repeatedly brought severe ecological and economic impacts to Chile, especially in the southern region, where the shellfish and salmon industries are world-famous. The mechanisms of such HABs have been intensively studied but are still unclear.

Toxic Alexandrium catenella expanding northward along the Chilean coast: New risk of paralytic shellfish poisoning off the Bío-Bío region (36° S).

In Chile, the toxic dinoflagellate A. catenella shows an apparent oceanic range expansion from south to the north since its first detection in 1972 in the Magallanes Region (56° S). Until 2017, A.

Development of an absolute quantification method for ribosomal RNA gene copy numbers per eukaryotic single cell by digital PCR.

Recent increase of Harmful Algal Blooms (HAB) causes world-wide ecological, economical, and health issues, and more attention is paid to frequent coastal monitoring for the early detection of HAB species to prevent or reduce such impacts. Use of molecular tools in addition to traditional microscopy-based observation has become one of the promising methodologies for coastal monitoring. However, as ribosomal RNA (rRNA) genes are commonly targeted in molecular studies, variability in the rRNA gene copy number within and between species must be considered to provide quantitative information in quantitative PCR (qPCR), digital PCR (dPCR), and metabarcoding analyses.

Disentangling the environmental processes responsible for the world's largest farmed fish-killing harmful algal bloom: Chile, 2016.

The dictyochophyte microalga Pseudochattonella verruculosa was responsible for the largest farmed fish mortality ever recorded in the world, with losses for the Chilean salmon industry amounting to US$ 800 M in austral summer 2016. Super-scale climatic anomalies resulted in strong vertical water column stratification that stimulated development of a dynamic P. verruculosa thin layer (up to 38 μg chl a L) for several weeks in Reloncaví Sound.

Unraveling the Karenia selliformis complex with the description of a non-gymnodimine producing Patagonian phylotype.

Karenia selliformis is a bloom-forming toxic dinoflagellate known for production of gymnodimines (GYMs) and causing mass mortalities of marine fauna. Blooms have been reported from coastal waters of New Zealand, Mexico, Tunisia, Kuwait, Iran, China and Chile. Based on molecular phylogeny, morphology, toxin production, pigment composition and cell growth of Chilean K.

Pelagic harmful algal blooms and climate change: Lessons from nature's experiments with extremes.

Time series now have sufficient duration to determine harmful algal bloom (HAB) responses to changing climate conditions, including warming, stratification intensity, freshwater inputs and natural patterns of climate variability, such as the El Niño Southern Oscillation and Pacific Decadal Oscillation. Against the context of time series, such as those available from phytoplankton monitoring, dinoflagellate cyst records, the Continuous Plankton Recorder surveys, and shellfish toxin records, it is possible to identify extreme events that are significant departures from long-term means. Extreme weather events can mimic future climate conditions and provide a "dress rehearsal" for understanding future frequency, intensity and geographic extent of HABs.

Interannual Variability of and in a Chilean Fjord: Insights from the Realized Niche Analysis.

Here, we present the interannual distribution of and over a 10-year period in the Reloncaví Fjord, a highly stratified fjord in southern Chile. A realized subniche approach based on the Within Outlying Mean Index (WitOMI) was used to decompose the species' realized niche into realized subniches (found within subsets of environmental conditions). The interannual distribution of both and summer blooms was strongly influenced by climatological regional events, i.

Fish gill damage by harmful microalgae newly explored by microelectrode ion flux estimation techniques.

Harmful algal blooms (HAB) are responsible for massive mortalities of wild and aquacultured fish due to noticeable gill damage, but the precise fish-killing mechanisms remain poorly understood. A non-invasive microelectrode ion flux estimation (MIFE) technique was successfully applied to assess changes in membrane-transport processes in a model fish gill cell line exposed to harmful microplankton. Net Ca, H, K ion fluxes in the rainbow trout cell line RTgill-W1 were monitored before and after addition of lysed cells of this Paralytic Shellfish Toxins (PST) producer along with purified endocellular dinoflagellate PST.

Role of resting cysts in Chilean Alexandrium catenella dinoflagellate blooms revisited.

The detection of sparse Alexandrium catenella-resting cysts in sediments of southern Chilean fjords has cast doubts on their importance in the recurrence of massive toxic dinoflagellate blooms in the region. The role of resting cysts and the existence of different regional Chilean populations was studied by culturing and genetic approaches to define: (1) cyst production; (2) dormancy period; (3) excystment success; (4) offspring viability and (5) strain mating compatibility. This study newly revealed a short cyst dormancy (minimum 69 days), the role of key abiotic factors (in decreasing order salinity, irradiance, temperature and nutrients) controlling cyst germination (max.

Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids.

Quantification of the role of reactive oxygen species, phycotoxins and fatty acids in fish toxicity by harmful marine microalgae remains inconclusive. An in vitro fish gill (from rainbow trout Oncorhynchus mykiss) assay was used to simultaneously assess the effect in superoxide dismutase, catalase and lactate dehydrogenase enzymatic activities caused by seven species of ichthyotoxic microalgae (Chattonella marina, Fibrocapsa japonica, Heterosigma akashiwo, Karenia mikimotoi, Alexandrium catenella, Karlodinium veneficum, Prymnesium parvum). Quantification of superoxide production by these algae was also performed.

T-lymphocyte phenotype and function triggered by Aggregatibacter actinomycetemcomitans is serotype-dependent.

Background And Objective: Based on lipopolysaccharide (LPS) antigenicity, different Aggregatibacter actinomycetemcomitans serotypes have been described. Serotype b strains have demonstrated a stronger capacity to trigger cytokine production on dendritic cells (DCs). As DCs regulate the development of T-lymphocyte lineages, the objective of this investigation was to study the response of T lymphocytes after being stimulated with autologous DCs primed with different bacterial strains belonging to the most prevalent serotypes of A.

[Long term follow up of patients consulting in a Chest Pain Unit].

Background: chest pain (CT) constitutes an important cause of consultation and diagnostic dilemma in the emergency room, especially due to the possible presence of coronary disease. Its presentation, diagnosis and prognosis are different between men and women.

Aim: to report a follow-up of patients attended at a Chest Pain Unit (CPU), evaluating gender differences.

Monocyte chemotactic protein-3: possible involvement in apical periodontitis chemotaxis.

Aim: To study the expression of monocyte chemotactic protein-3 (MCP-3, also known as chemokine CCL-7) in tissue from apical lesions (AL) and to associate MCP-3 expression with symptomatic or asymptomatic apical periodontitis.

Methodology: To determine the expression of MCP-3 in AL, biopsies obtained during tooth extraction procedures were fixed, subjected to routine processing and diagnosed as apical granuloma (AG) (n = 7) or radicular cyst (RC) (n = 5). As controls, apical periodontal ligament (PDL) specimens from healthy premolars extracted for orthodontics reasons were included (n = 7).

[Chest pain unit: first experience in Chile].

Background: In large series, nearly 60% of admissions for suspected acute coronary syndrome (ACS) had a non-coronary etiology of the pain. However, short term mortality of non recognized ACS patients, mistakenly discharged from the emergency room is at least twice greater than the expected if they would had been admitted. The concept of a chest pain unit (CPU) is a methodological approach developed to address these issues.

Andes Hantavirus as possible cause of disease in travellers to South America.

Background: Hantaviruses in Europe and Asia cause haemorrhagic fever with renal syndrome and epidemic nephritis (mortality rate <1-15%). New strains of Hantaviruses cause Hantavirus pulmonary syndrome (HPS) from Canada to South America. Andes virus mortality rate is about 30% in Chile.

Prevalence of antibodies to hantavirus among family and health care worker contacts of persons with hantavirus cardiopulmonary syndrome: lack of evidence for nosocomial transmission of Andes virus to health care workers in Chile.

Nosocomial transmission of Andes virus has been documented in Argentina, but has not yet been proven in Chile. We studied 215 contacts (106 family member contacts and 109 health care worker contacts) of 20 index cases of hantavirus cardiopulmonary syndrome (HCPS) in Chile. The seroprevalence of IgG antibodies against Andes virus was 1.

[Prevalence of anti-hantavirus antibodies in health care personnel in direct contact with patients with hantavirus pulmonary syndrome in Temuco, Chile 1997 to 1999].

Background: An outbreak of Hantavirus Cardiopulmonary Syndrome (HVCS) caused by the Andes virus, affected Chile since 1995. Antibodies to Hantavirus in health care workers who had cared patients with HVCS in Coybaique, Argentinean reports and familial clustering of bantaviral illness, raised the possibility of person to person transmission. Familial clustering could occur secondary to a similar exposure to a common infected environment of more than one member of the family.