El estado actual del estudio de florecimientos algales nocivos en México

This review presents an analysis of the state of knowledge of harmful algae studies in the marine environment in Mexico, in order to evaluate how we can optimize the available resources to study these events, identify unattended issues, and propose improvements in monitoring and/or research programs that could help to further understand the complexity of HAB in our coasts. An exhaustive bibliographic revision, from 1940 to 2011, was done consulting specialized data analyses, conference meetings, and specialized books and manuals. The number of researchers and institutions involved in HAB (harmful algal blooms) studies has increased significantly during the last decades, which is reflected in the number and quality of publications. However most of the existing HAB reports are based on sporadic sampling and short-term research programs. Monitoring programs and research activities have been focused in only a few HAB species; many toxic and harmful microalgal species have not been considered. To date, there is no laboratory with the capacity and techniques to analyze all the phycotoxins detected in Mexican coasts. Also, many research areas have not been attended adequately in Mexico such as cyst studies, allelophaty, exotic species, effect of climate change, use of molecular tools and teledetection, socioeconomic analyses, and mitigation strategies among others. This review shows that there has been a significantly improvement in the study of HAB in Mexico. However the studies are still addressed under an individual and disperse way and lack coordination. Greater achievements would be obtained if we concentrate the efforts of researchers and institutions were coordinated in order to optimize the available resources for HAB studies.Esta revisión da a conocer el estado de conocimiento de los estudios de Florecimientos Algales Nocivos (FAN) en el ámbito marino en México, con el objeto de evaluar la manera de optimizar los recursos destinados para el estudio de FAN en nuestro país, identificando líneas no abordadas y proponiendo mejoras en las actividades de monitoreo y de investigación que puedan aumentar nuestro conocimiento sobre la complejidad de FAN en nuestras costas. Se realizó una búsqueda bibliográfica de 1940 a 2011 consultando bases de datos, reuniones académicas y libros especializados. El número de investigadores e instituciones involucrados con el estudio de FAN se ha incrementado significativamente en las últimas décadas, lo cual se ve reflejado en el número y calidad de las publicaciones. Sin embargo, la mayoría de los programas y actividades de investigación están basados en muestreos puntuales y programas de investigación a corto plazo, enfocándose a pocas especies de FAN. Actualmente, varias líneas de investigación relacionadas con los FAN se han abordado pobremente o no se han considerado como son los estudios sobre quistes, alelopatía, transportación de especies por aguas de lastre, efecto del cambio climático, utilización de imágenes de satélite, uso de herramientas moleculares, análisis socioeconómicos y estrategias de mitigación, entre otros. Este análisis muestra que ha habido un avance significativo en el estudio de FAN en México, si bien la manera de abordar su estudio ha sido individualizada y dispersa. Se obtendría un mayor avance si se coordinaran los esfuerzos entre los diversos investigadores e instituciones para optimizar los recursos disponibles para el estudio de los FAN

Exploring marine toxins: comparative analysis of chemical reactivity properties and potential for drug discovery

Marine toxins, produced by various marine microorganisms, pose significant risks to both marine ecosystems and human health. Understanding their diverse structures and properties is crucial for effective mitigation and exploration of their potential as therapeutic agents. This study presents a comparative analysis of two hydrophilic and two lipophilic marine toxins, examining their reactivity properties and bioavailability scores. By investigating similarities among these structurally diverse toxins, valuable insights into their potential as precursors for novel drug development can be gained. The exploration of lipophilic and hydrophilic properties in drug design is essential due to their distinct implications on drug distribution, elimination, and target interaction. By elucidating shared molecular properties among toxins, this research aims to identify patterns and trends that may guide future drug discovery efforts and contribute to the field of molecular toxinology. The findings from this study have the potential to expand knowledge on toxins, facilitate a deeper understanding of their bioactivities, and unlock new therapeutic possibilities to address unmet biomedical needs. The results showcased similarities among the studied systems, while also highlighting the exceptional attributes of Domoic Acid (DA) in terms of its interaction capabilities and stability

Toxinas paralizantes en moluscos bivalvos durante una proliferación de Gymnodinium catenatum Graham en la Bahía de La Paz, México

From February to March 2007 a harmful algae bloom of Gymnodinium catenatum Graham ocurred in Bahía de La Paz, Mexico, with cell densities from 6 x 105 to 2,39 x 106 cells L-1. During this event the toxin concentration and toxin profile of paralytic shellfish toxins in mollusks (Pinna rugosa, Modiolus capax, Megapitaria squalida, Periglypta multicostata, Dosinia ponderosa, and Megapitaria aurantiaca), and in phytoplankton samples were determined. Some physicochemical data were obtained. The average values of the surface temperature and dissolved oxygen were 20.9 ± 0.7 °C and 6.9 ± 0.3 mg L-1. The average concentrations of nitrites, nitrates, ammonium, phosphates, and silicates were 0.22 ± 0.05, 1.04 ± 0.33, 0.89 ± 0.88, 0.81 ± 0.76, and 8.85 ± 1.60 µM, respectively. The concentration of paralytic shellfish toxins in the net phytoplankton samples varied from 4.32 to 79.60 ng saxitoxin equivalents filter-1, identifying 8 toxins, the most abundant being C1 and C2. The highest toxin concentration found in mollusks were 31.14, 37.74, and 25.89 µg STXeq 100 g-1 in M. capax, P. rugosa, and M. aurantiaca, respectively. The variations in the paralytic toxin profile in the different mollusks species are given.De febrero a marzo de 2007, se presentó una proliferación de Gymnodinium catenatum Graham en la Bahía de La Paz (México), con densidades de 6 x 105 a 2,39 x 106 cél. L-1. Durante este evento se determinó la concentración y el perfil de toxinas paralizantes en moluscos bivalvos (Pinna rugosa, Modiolus capax, Megapitaria squalida, Periglypta multicostata, Dosinia ponderosa y Megapitaria aurantiaca) y en muestras de fitoplancton. También se obtuvieron algunos parámetros físicos y químicos. Los valores promedios de la temperatura superficial y del oxígeno disuelto fueron de 20.9 ± 0.7 °C y 6.9 ± 0.3 mg L-1, respectivamente. Las concentraciones promedios de nitritos, nitratos, amonio, fosfatos y silicatos fueron de 0.22 ± 0.05, 1.04 ± 0.33, 0.89 ± 0.88, 0.81 ± 0.76 y 8.85 ± 1.60 µM, respectivamente. El contenido de toxinas paralizantes en las muestras de arrastres de red variaron de 4.32 a 79.60 ng saxitoxina equivalente filtro-1, identificándose 8 toxinas, siendo la C1 y C2 las dominantes. Las máximas concentraciones de toxinas paralizantes en los moluscos fueron de 31.14, 37.74 y 25.89 µg STXeq. 100 g-1 en M. capax, P. rugosa y M. aurantiaca, respectivamente. Se dan a conocer las variaciones en el perfil de toxinas paralizantes en las diversas especies de moluscos

Population Dynamics of Benthic-Epiphytic Dinoflagellates on Two Macroalgae From Coral Reef Systems of the Northern Mexican Caribbean

In the present study the abundance of epiphytic dinoflagellates was evaluated at two coral reef sites of the natural protected areas, Arrecife de Puerto Morelos and Isla Contoy, located in the northern Mesoamerican Reef System of the Mexican Caribbean. Abundances were monitored from April to December, 2015 on two genera of macroalga belonging to different functional groups: Dictyota and Amphiroa. In general, the total abundance of dinoflagellates was higher in Puerto Morelos on both macroalgae. Ostreopsis cf. marina and O. heptagona were the dominant species. Relative abundance of these species varied from 8 to 99% of total epiphytic dinoflagellates. Maximum abundances at Puerto Morelos were registered in April, with 33,801 cells·g−1 on Dictyota and 6,264 cells·g−1 on Amphiroa. In Isla Contoy the maximum abundance was 16,006 cells·g−1 and it was detected on Dictyota during December. Other dinoflagellate genera were more abundant during the warmer period (May–September) in both locations. Prorocentrum was the second most abundant genus and was represented by six species (P. hoffmannianum, P. lima, P. belizeanum, P. elegans, P. emarginatum, and P. rathymum). The maximum pooled abundance of Prorocentrum species was 4,144 cells·g−1 on Dictyota in August. Coolia spp. did not reach abundances higher than 1,000 cells·g−1 and Gambierdiscus spp. only exceeded 100 cells·g−1 during August. Mean water temperature in Isla Contoy was significantly lower than that of Puerto Morelos during the entire study period. There was a negative correlation between the water temperature and the abundance of O. cf. marina. The dominance of Ostreopsis in the Caribbean is significant because of its capability to produce palytoxin analogs and its potential role in ciguatera fish poisoning outbreaks in the region. This is the first study that reports blooms of Ostreopsis in Mexican Caribbean coral reefs, a fact that emphasizes the significance of this genus at global scale

Paralytic Toxin Producing Dinoflagellates in Latin America: Ecology and Physiology

In this review we summarize the current state of knowledge regarding taxonomy, bloom dynamics, toxicity, autoecology, and trophic interactions, of saxitoxin producing dinoflagellates in this region. The dinoflagellates Gymnodinium catenatum, Pyrodinium bahamense and several species of Alexandrium are saxitoxin producers, and have been responsible of paralytic shellfish poisoning in different regions of Latin America, causing intoxications and important fisheries losses. The species distribution differ; most harmful algal blooms of G. catenatum are from the northern region, however this species has also been reported in central and southern regions. Blooms of P. bahamense are mostly reported in North and Central America, while blooms of Alexandrium species are more common in South America, however this genus is widely spread in Latin America. Species and regional differences are contrasted, with the aim to contribute to future guidelines for an international scientific approach for research and monitoring activities that are needed to increase our understanding of paralytic toxin producing dinoflagellates in this region

Toxicity of Cultured Bullseye Puffer Fish Sphoeroides annulatus

The toxin content in various life cycle stages of tank-cultivated bullseye puffer (Sphoeroides annulatus) were analyzed by mouse bioassay and ESI-MS spectrometry analysis. The presence of toxin content was determined in extracts of sperm, eggs, embryo, larvae, post-larvae, juvenile, pre-adult, and adult fish, as well as in food items used during the cultivation of the species. Our findings show that only the muscle of juveniles, the viscera of pre-adults, and muscle, liver, and gonad of adult specimens were slightly toxic (<1 mouse unit). Thus, cultivated S. annulatus, as occurs with other cultivated puffer fish species, does not represent a food safety risk to consumers. This is the first report of toxin analysis covering the complete life stages of a puffer fish under controlled conditions

Ecological and Physiological Studies of Gymnodinium catenatum in the Mexican Pacific: A Review

This review presents a detailed analysis of the state of knowledge of studies done in Mexico related to the dinoflagellate Gymnodinium catenatum, a paralytic toxin producer. This species was first reported in the Gulf of California in 1939; since then most studies in Mexico have focused on local blooms and seasonal variations. G. catenatum is most abundant during March and April, usually associated with water temperatures between 18 and 25 ºC and an increase in nutrients. In vitro studies of G. catenatum strains from different bays along the Pacific coast of Mexico show that this species can grow in wide ranges of salinities, temperatures, and N:P ratios. Latitudinal differences are observed in the toxicity and toxin profile, but the presence of dcSTX, dcGTX2-3, C1, and C2 are usual components. A common characteristic of the toxin profile found in shellfish, when G. catenatum is present in the coastal environment, is the detection of dcGTX2-3, dcSTX, C1, and C2. Few bioassay studies have reported effects in mollusks and lethal effects in mice, and shrimp; however no adverse effects have been observed in the copepod Acartia clausi. Interestingly, genetic sequencing of D1-D2 LSU rDNA revealed that it differs only in one base pair, compared with strains from other regions

Superoxide dismutase activity in juvenile Litopenaeus vannamei and Nodipectensubnodosus exposed to the toxic dinoflagellate Prorocentrum lima

The toxic effect of the dinoflagellate Prorocentrum lima on juvenile American whiteleg shrimp Litopenaeus vannamei and giant lion-paw scallop Nodipecten subnodosus was evaluated. Organisms were exposed to three densities (500, 2000, or 5000 cells mL-1), superoxide dismutase activity and soluble protein in the hepatopancreas and muscle were determined at 1, 6, 24 and 48 h after challenge. Shrimp exposed at 5000 cells mL-1 significantly increased SOD activity in the hepatopancreas at 1 h post-challenge, whereas enzymatic activity in muscle significantly increased at 24 h at all densities. Scallops exposed to 500 and 2000 cells mL-1 showed significant SOD activity increase in hepatopancreas at 24 and 12 h, respectively. Mortality at 48 h was 100% in scallops exposed to 5000 cells mL-1. Shrimp showed higher levels of SOD activity than scallops. Soluble protein content in the shrimp hepatopancreas was significantly higher at densities of 500 and 2000 cells mL-1 at 6 and 1 h, respectively. Soluble protein content in the scallop hepatopancreas was higher than control values at 1 h after challenge. In this study, 500 cells mL-1 was enough to trigger SOD activity in two benthic species exposed to the toxic dinoflagellate P. lima

Grazing of the dinoflagellate Noctiluca scintillans on the paralytic toxin-producing dinoflagellate Gymnodinium catenatum: Does grazing eliminate cells during a bloom?

Temperature and nutrient concentrations were measured during a mixed bloom of Noctiluca scintillans and Gymnodinium catenatum in La Paz Bay, Gulf of California. Under laboratory conditions, we offered three concentrations of G. catenatum (312, 625, or 1015 cells mL–1) to 0.53 N. scintillans cells mL–1 to study predation rates. Experiments were carried out with 750 mL of culture during a fiveday period. Sea surface temperature clearly showed a transitional period from colder to warmer water during the bloom. Field and laboratory data showed that N. scintillans fed on G. catenatum. During the trial, more than 70% of N. scintillans cells contained G. catenatum cells in their vacuoles. Ingestion rates varied; the highest ranged from 30 to 40 G. catenatum cells h–1 in each N. scintillans cell. A clear relation to the concentration of the diet was not evident. Low values of 1 to 3 G. catenatum cells h–1 in each N. scintillans cell were typical at the end of the trial. Noctiluca scintillans doubled in concentration about every 48 h; however, numerous trophonts were observed leaving the cytoplasmic membrane, suggesting cell damage. These data indicate that N. scintillans ingests G. catenatum cells but the prey appears to damage predator cells in a relatively short time.

Effect of dissolved metabolites of the dinoflagellate Gymnodinium catenatum (Graham, 1943) on the white shrimp Litopenaeus vannamei (Boone, 1931): A histological study

Harmful algae blooms (HABs) are a conspicuous phenomenon that affect the coastal zone worldwide. Aquaculture industry zones are not excluded from being affected by HAB that cause organism mortality and jeopardize their innocuity due to the contamination by phytotoxins with the concomitant economic losses. Direct ingestion of metabolites from HAB species or organisms contaminated with phycotoxins together with dermal absorption of dissolved metabolites (DM), including toxins, are the two main routes of poisoning. From these poisoning routes, the effect of DM, particularly paralytic shellfish toxins (PST), has been relatively understudied. This intoxication route can be conspicuous and could be involved in many significant mortalities of cultivated marine organisms. In this study, white shrimp juveniles (2.1 g wet weight) of Litopenaeus vannamei were exposed to extracts of 104, 105 and 106 cells/L of the dinoflagellate Gymnodinium catenatum, a PST producer. The experiment ended after 17 h of exposure when shrimps exposed to 106 cells/L extract started to die and the rest of the shrimps, from this and other treatments, did not respond to gentle physical stimulus and their swimming activity was low and erratic. Toxin concentrations were determined using high performance liquid chromatography while qualitative and quantitative histological damages were assessed on the tissues. In general, most toxins were accumulated in the hepatopancreas where more than 90% were found. Other tissues such as intestine, muscle, and gills contained less than 10% of toxins. Compared to the control, the main significative tissue damages were, loss of up to 80% of the nerve cord, 40% of the muscle coverage area, and reduction of the gill lamella width. Also, atrophy in hepatopancreas was observed, manifested by a decrease in the height of B cells, lumen degeneration and thinning of tubules. Some damages were more evident when shrimps were exposed to higher concentrated extracts of G. catenatum, however, not all damages were progressive and proportional to the extract concentration. These data confirm that PST dissolved enter the shrimp, possibly via the gills, and suggest that dissolved metabolites, including PST, may cause tissue damage. Other dissolved metabolites produced by G. catenatum, alone or in synergy, may also be involved. These results also pointed out the importance of dissolved molecules produced for this dinoflagellate and the potential effect on cultured shrimp