Changes in activity of hepatic xenobiotic-metabolizing enzymes of tiger puffer (Takifugu rubripes) exposed to paralytic shellfish poisoning toxins.

Attempts were made to examine the effect of paralytic shellfish poisoning toxins (PSP) on hepatic xenobiotic-metabolizing enzymes (XMEs) of tiger puffer (Takifugu rubripes). Two groups of nontoxic tiger fish were analyzed, and one group was fed with a PSP-containing diet (PSP group), and another with a PSP-free diet (control group). After 60 days of feeding, they were compared to each other mainly in terms of the activity of XMEs. Both groups did not differ from each other significantly in body weight gain, hepatosomatic index, and condition factor Hepatic level of cytochrome P450 was lower in PSP group than control group. NADPH-cytochrome P450 reductase, NADH-cytochrome b5 reductase, and ethoxyresorufin-O-deethylase (EROD) exhibited a reduced activity in PSP group than control group. Statistical analysis found that the activity or concentration of those enzymes correlated with the hepatic level of PSR with r2=0.497-0.611.

Acute toxicity effect of the venom of the marine snail, Conus zeylanicus.

Acute toxicity of the venom of Conus zeylanicus was studied to evaluate its risk and toxic factors in view of human safety The lethality of the crude venom (LD50 -60 mg/kg via i.p.) in mice was associated with increased heart rate and strong muscular hind limb paralysis, skeletal muscle paralysis, dyspnea, loss of spontaneous activity followed by respiratory failure. The effect on vital tissues revealed liver tissues were disrupted with hemorrhagic necrosis and the lung showed the pathogenic changes of diffused inflammation of the parenchyma and obliteration of the alveolar space. In brain, edema was observed throughout the parenchyma and the kidney shows the tubules with cloudyswelling of the lining cells and the parenchyma inflammation and few inflammatory cells infiltration.

Human intoxication with paralytic shellfish toxins: clinical parameters and toxin analysis in plasma and urine

This study reports the data recorded from four patients intoxicated with shellfish during the summer 2002, after consuming ribbed mussels (Aulacomya ater) with paralytic shellfish toxin contents of 8,066 n 61.37 mg/100 gr of tissue. Data associated with clinical variables and paralytic shellfish toxins analysis in plasma and urine of the intoxicated patients are shown. For this purpose, the evolution of respiratory frequency, arterial blood pressure and heart rate of the poisoned patients were followed and recorded. The clinical treatment to reach a clinically stable condition and return to normal physiological parameters was a combination of hydration with saline solution supplemented with Dobutamine (vasoactive drug), Furosemide (diuretic) and Ranitidine (inhibitor of acid secretion). The physiological condition of patients began to improve after four hours of clinical treatment, and a stable condition was reached between 12 to 24 hours. The HPLC-FLD analysis showed only the GTX3/GTX2 epimers in the blood and urine samples. Also, these epimers were the only paralytic shellfish toxins found in the shellfish extract sample.

Blooms of Cochlodinium polykrikoides (Gymnodiniaceae) in the Gulf of California, Mexico

Cochlodinium polykrikoides was the species responsible for the discoloration that occurred between September 15th and 27th , 2000 in a shallow coastal lagoon located in the southern part of the Bahía de La Paz, on the west side of the Gulf of California. Blooms of C. polykrikoides were observed four days after two rainy days with a seawater temperature of 29 to 31°C. Nutrient concentration ranges during the bloom were 0.165- 0.897 µM NO2 +NO3 , 0.16-3.25 µM PO4 , and 1.0-35.36 µM SiO4 . Abundance of C. polykrikoides ranged from 360 x 103 to 7.05 x 106 /cells l-1 . Biomass expressed in terms of chlorophyll a was high, ranging from 2.7 to 56.8 mg/m3 . A typical dinoflagellate pigment profile (chlorophyll a and c, peridinin, diadinoxantin, and b -carotene) was recorded. In this study, the red tide occurred in front of several fish and shrimp-culture ponds. No PST toxins were found in the samples. However, 180 fish were found dead in the infected fish-pond; the gills were the most affected part. C. polykrikoides is a cyst-forming species that recurs in this area. New blooms were observed in November 2000 and September-November 2001 in the same area. Anthropogenic activities, such as eutrophication caused by water discharge in this shallow lagoon, and nutrient enrichment in the culture ponds, as well as effects from precipitation and wind stress, could have favored the outbreak of this dinoflagellate

Durante el desarrollo de una marea roja ocurrida del 15 al 27 de septiembre del año 2000 en la Ensenada de La Paz, B.C.S. se tomaron muestras de agua con una botella Van Dorn para determinar la temperatura, la especie causante y la cantidad de nutrientes y pigmentos fotosintéticos. Se hicieron análisis de toxinas de Cochlodinium polykrikoides, la especie responsable de esta marea roja. La mayoría de los especimenes formaron cadenas de cuatro células y raramente de dos. La abundancia fue de 360 x 103 a 7.05 x 106 /cels l-1 . Los florecimientos de C. polykrikoides ocurrieron cuatro días después de dos días lluviosos; el intervalo de temperatura fue de 29 a 31°C. La concentración de nutrientes registrada durante este fenómeno fue 0.165-0.897 µM NO2 +NO3 , 0.16-3.25 µM PO4 , y 1.0-35.36 µM SiO4 . El perfil pigmentario reveló la presencia de clorofila a y c, peridinina, diadinoxantina, y b -caroteno. La biomasa total expresada en clorofila a fue alta, oscilando entre 2.7 y 56.8 mg/m3 , mientras que la biomasa de Cochlodinium, expresada en peridinina, varió entre 0.68 y 32.03 mg/m3 . En este estudio, la marea roja se desarrolló cerca de varios estanques de cultivo de peces y camarón. En uno de ellos proliferó C. polykrikoides. Los análisis de toxinas PST fueron negativos; sin embargo, durante el incremento de las proliferaciones algunos estanques fueron alcanzados y murieron 180 peces, principalmente pargos (Lutjanus argentiventis, Pomadasys macracantus). Las branquias fueron las partes más afectadas. En condiciones desfavorables C. polykrikoides forma quistes, lo cual ha provocado su recurrente proliferación en el área, registrándose nuevas proliferaciones en noviembre del 2000 y en septiembre-noviembre del 2001. Actividades antropogénicas como la eutroficación causada por la descarga de aguas residuales y de nutrientes de los estanques de cultivo, pudieran estar favoreciendo la proliferación de este dinoflagelado

Dinámica espacio-temporal de organismos precursores de marea roja en la costa Pacífica de América del Norte y Centroamérica / Spatial-temporal dynamics of red tide precursor organisms at the Pacific coast of North and Central America

La región costera del Pacífico de Centro y Norte America ha sido afectada de manera frecuente por fenómenos que se denominan proliferaciones algales nocivas o en inglés, "Harmful Algal Blooms" (HAB). A pesar de la gran cantidad de efectos en la salud pública, las actividades económicas y el medio ambiente, aún existe una abrumadora carencia de información en el tema. Esto no permite establecer si las causas principales de este evidente aumento en el número e intensidad de los eventos son naturales o antropogénicas. La incrementada utilización de las zonas costeras para actividades humanas encuentra paralelo en el denominado cambio climático, lo que dificulta discriminar entre la posible influencia de estos dos fenómenos. Series de datos de larga duración en regiones reducidas, así como las observaciones esporádicas realizadas cuando se presenta algún evento, nos permite comparar regímenes climáticos, condiciones geográficas, disponibilidad de nutrientes (incluyendo la eutroficación) y parámetros oceanográficos que promueven o permiten el desarrollo y mantenimiento de las proliferaciones, haciendo evidentes cambios drásticos en la biodiversidad y la biogeografía de los organismos productores de HAB

The Pacific coast of Central and North America has long been and still is impacted by the flourishing of microalgal populations known as Harmful Algal Blooms (HABs). The organisms that have caused recent HABs episodes in the region are among others, Gymnodinium catenatum, Pyrodinium bahamense var. compressum, and recently Cochlodinium cf. catenatum. In spite of the accumulated effects on the human health, the economic activities and the environment, scarce information is available on the subject. The augmented use of coastal zones for human activities is also paralleled by increased awareness of global climate changes. Thus, it is not an easy task to discriminate anthropogenic or natural phenomena, or both, as the major driving forces. The long-term data sets available for limited regions, as well as some sporadic observations during notorious blooms, allowed us to discriminate major changes in the biodiversity and biogeography of HAB organisms. Main changes refer to number of events, covered area, duration and frequency, number of blooming species and appearance of not previously reported harmful taxa. The variables more clearly related to these dynamic phenomena, seems to be sea surface temperature and wind force, but it is not yet possible to weight their contributions. The participation of rain is not fully evaluated to date. The collaborative communication among small-budget monitoring operations in the region allowed to "pass the voice" about peaking concentrations of HAB organisms, diminishing the risk of poisoning

Mechanism of cardiotoxicity induced by a marine toxin isolated from Ptychodiscus brevis.

An organophosphate toxin of marine origin isolated from red tide dinoflagellate P. brevis produced a dose-dependent dual effect on rat atria, i.e. positive inotropic effect at low concentrations (2.8 x 10(-8) to 8.4 x 10(-7) M) and negative inotropic and chronotropic responses at an elevated dose (4.8 x 10(-6) to 7.2 x 10(-4) M). The negative chronotropic and inotropic responses of the toxin were potentiated with physostigmine and ouabain whereas antagonized by atropine and hemicholinium-3 pretreatments and those effects remained unaltered by isoproterenol, phenylephrine and ouabain pretreatments. The results indicate that the toxin induced negative inotropic and chronotropic effects are mediated through release of acetylcholine from the nerve endings and consequent activation of muscarinic receptor. In atria exposed to guanethidine, bretylium, propranolol and tyramine tachyphylaxis, the positive inotropic response of the toxin was not modified. However, the response was antagonized by EGTA, nifedipine, ryanodine, calcium-free ringer and potentiated with caffeine and amiloride pretreatments. The results suggest that the positive inotropic effect of the toxin is mediated through Ca2+ influx and impairment of Na+/Ca2+ exchange process.

Brevetoxin-3 (PbTx-3) on mouse liver slices: a histological study

Brevetoxin-3 (PbTx-3) is a marine toxin produced by the dinoflagellate Ptychodiscus brevis. Its effects on excitable tissues have been the main subject of studies, but little is known about how it affects non-excitable tissues. To study possible non-neural effects of PbTx-3 (78nM), its effects on hepatic cell structure in vitro were evaluated. PbTx-3 caused hypertrophy and increased vacuolation of hepatocytes, and an increase in basophilia in the perivenous area of the lobules. Ultrastructurally, it was evident that the vacuolation was related to swelling of the endoplasmic reticulum, changes that probably account for the increased basophilic reaction of the cells. The swelling in smooth endoplasmic reticulum, degranulation of rough endoplasmic reticulum, the deformities and lytic cristae in the mitochondria, and the presence of active lysosomes are evidence of the PbTx-3 effects upon liver cells. These responses are probably caused by the liver's detoxification role on the PbTx-3.