Lourdes Segura-Puertas

A venom extract from the sea anemone Bartholomea annulata produces haemolysis and lipid peroxidation in mouse erythrocytes

The haemolytic and peroxidative effects of crude extracts from Bartholomea annulata, a common Caribbean sea anemone, were investigated in erythrocytes isolated from NIH male albino mice. Significant concentration-dependent effects were found on both haemolysis (evaluated as release of haemoglobin) and lipid peroxidation (as a common index of oxidative damage to membrane lipids) in red blood cells. Moreover, the incubation of erythrocytes in the presence of either a general antioxidant, reduced glutathione (GSH, 50 microM), or an iron chelator, desferrioxamine (DFA, 10 microM), resulted in a significant attenuation of haemolysis in both cases. In light of these findings, the in vitro toxicological characterization of the venom, as well as the involvement of oxygen radical-mediated membrane damage as a potential mechanism of toxicity associated with haemolysis are discussed.

Some toxinological aspects of Aurelia aurita (Linné) from the Mexican Caribbean

Aurelia aurita is a scyphozoan, abundant in the Mexican Caribbean during summer. Although usually innocuous, there is evidence of it causing harm to humans. This work investigates the biological activities of crude and fractionated extracts of A. aurita. Live specimens were collected between July and September 1999 from the Mexican Caribbean. The tentacular margin was dissected immediately and frozen at -50oC. A nematocyst suspension was prepared, discharged, and the supernatants lyophilized. Hemolytic assay was performed with lyophilized crude extract on bovine, sheep, and human red blood cells. Erythrocyte sensitivity to the toxin was ranked in descending order: human, sheep, and bovine. Toxic activity on Artemia nauplii was evaluated using the same crude extract for different exposure periods (3, 5, and 10 hours); only 48 and 72 hour old Artemia nauplii showed 50% mortality. Partial toxin purification was completed by sequential liquid chromatography using three gels (Sephadex G-200, DEAE Sephadex A-50, and Sephadex G-100). Intramuscular neuroactivity was detected in the crab Ocypode quadrata for two partially purified fractions. These fractions were found to have molecular weight components of 66 and 45 kDa, respectively.

Summer composition and distribution of the jellyfish (Cnidaria: Medusozoa) in the shelf area off the central Mexican Pacific

Se estudio la composicion, distribucion y abundancia de la comunidad de medusas de la plataforma continental en el Pacifico mexicano durante agosto 1988. Las muestras de zooplancton provienen de transectos en las zonas externa e interna de la plataforma para determinar la estructura de la comunidad de medusas y su variacion durante la epoca de lluvias. Se identificaron 23 especies; las mas abundantes fueron Aglaura hemistoma, Solmundella bitentaculata, Liriope tetraphylla, Pelagia noctiluca y Rhopalonema velatum. La abundancia total de las medusas y la de las especies mas abundantes fue estadisticamente independiente de la profundidad y de la distancia a la costa. Por tanto, la abundancia total de las medusas, la de las especies mas abundantes y la diversidad de Shannon tuvieron una distribucion uniforme en ambas zonas, interna y externa de la plataforma. Adicionalmente, las formas neritico-oceanicas y las plenamente oceanicas se presentaron de manera indistinta a traves de la plataforma. En la parte externa de la plataforma A. hemistoma y S. bitentaculata fueron las especies mas abundantes; por su parte, la primera de estas, junto con L. tetraphylla, caracterizaron aunque debilmente, la comunidad de medusas de la parte interna de la plataforma. La estrechez de la plataforma, la amplia distribucion de las especies mas abundantes y los posibles efectos locales de procesos advectivos desde la zona oceanica ocultaron un gradiente definido a traves de la plataforma. Se encontraron 3 especies que no habian sido registradas previamente en el Pacifico mexicano: Amphinema dinema (Peron and Lesueur, 1810), Sarsia coccometra Bigelow, 1909, y Clytia mccradyi (Brooks, 1888). La presencia de A. dinema representa el primer registro de esta especie en el Pacifico oriental.

Antimicrobial, Antiprotozoal, and Toxic Activities of Cnidarian Extracts from the Mexican Caribbean Sea

Abstract Antimicrobial, antiprotozoal, and toxic activities of crude extracts obtained from six cnidarian species [Cassiopea xamachana. (R.R. Bigelow, 1892), Carybdea marsupialis. (Linné, 1758), Linuche unguiculata. (Swartz, 1788), Bartholomea annulata. (Leseur, 1817), Lebrunia danae. (Duchassaing and Michelotti, 1860), and Stichodactyla helianthus. (Ellis, 1768)] from the Mexican Caribbean Sea were studied. The extract obtained from Linuche unguiculata. was found to be the most active against the yeast Candida albicans. and the protozoan Giardia lamblia. with 24 mm of inhibition zone diameter and an IC50 of 63.2 µg mL−1, respectively. Additionally, in an effort to assess the effects caused by the treatment of cnidarians toxins in vertebrates, we used tilapias (Oreochromis niloticus.) as a laboratory model. The results showed that only 44 mg kg−1 of jellyfish (Carybdea marsupialis.) toxin were necessary to cause significant mortality in fish. Tilapias treated with the Stichodactyla. toxin demonstrated hemolytic damage and cellular abnormalities.

Hemiurid Metacercariae (Trematoda) in Chaetognaths from the Mexican Caribbean Sea

Abstract Examination of coelomic cavities of 22,508 chaetognaths revealed the presence of 19 hemiurid metacercariae representing 3 genera as follows: Brachyphallus sp. from Serratosagitta serratodentata, Ectenurus sp. from Parasagitta friderici, and Lecithochirium sp. from Flaccisagitta enflata, S. serratodentata, Sagitta bipunctata, and Sagitta helenae. Samples were collected along the Mexican coast of the Caribbean Sea from 50 m depth to surface during February, March, May, and August 1991. Overall prevalence and mean infection intensity were 0.084% and 1.0, respectively. Serratosagitta serratodentata and S. helenae represent new host records for hemiurids.

An Accacoeliid Metacercaria Parasitizing the Arrow Worm Flaccisagitta enflata (Grassi, 1881) from the Mexican Caribbean Sea

Abstract Trematode larvae of the family Accacoeliidae were obtained from Flaccisagitta enflata collected in the Mexican Caribbean Sea during February, March, May, and August 1991. Two parasites were found in the coeloms of 2 chaetognaths of 14,583 examined (prevalence = 0.014%; intensity = 1). The parasites have 5 or 6 branches on each side of the anterior intestinal ceca and 2 deeply stained zones, 1 internal on the posterior edge of the acetabulum and the other a glandular structure around the cloacal pore in the posterior part of the body. Two tegumental folds are present on the anterior and posterior parts of the parasite. These trematode larvae, their host, and their occurrence in the Mexican Caribbean Sea are reported for the first time.

Figure 11 In First Inventory Of Sea Anemones (Cnidaria: Actiniaria) Of The Mexican Caribbean

FIGURE 11. — Ragactis lucida. (A) Live specimen in natural habitat. (B) Oral view