Marine organisms are rich sources of natural products that, among other activities, help to maintain the species equilibrium. Samples of the marine brown alga Canistrocarpus cervicornis (Kützing) De Paula & De Clerck were collected in Búzios, Rio de Janeiro, Brazil, in June 2006. The extract was obtained in CH2Cl2 and subjected to fractionation by chromatographic methods in order to isolate and purify the compound (4R, 7R, 14S)-4α, 7α-diacethoxy-14-hydroxydolastane-1(15), 8-dien. Then, the effects of the extract and the dolastane diterpene on zygotes and gametes of the sea urchin Lytechinus variegatus were evaluated. The exposure of male and female gametes to the C. cervicornis extract promoted, respectively, a reduction of 10-30% in fertilization and a 20 to 70% decrease in the number of eggs. Furthermore, the exposure of zygotes to the extract inhibited their development up to 86.7 ± 1.6% (at a concentration of 250 µg mL-1), as well as generating abnormalities in 39-50% of zygotes. The results of the dolastane diterpene showed no evidence of inhibition in the zygotes' development, thought it was proved to induce anomalies. At higher concentrations (25 and 50 µg mL-1), it was possible to observe cell lyses.

Los organismos marinos son fuentes ricas en productos naturales que, entre otras actividades, ayudan a mantener el equilibrio entre las especies. Se colectaron muestras de Canistrocarpus cervicornis (Kützing) De Paula & De Clerck en Armação de Búzios, Estado de Rio de Janeiro, Brasil, durante junio de 2006 y se sometieron a extracción en CH2Cl2 hasta obtener un extracto bruto. Mediante técnicas tradicionales de fitoquímica se aisló y purificó el producto natural mayoritario dolastano (4R, 7R, 14S)-4α, 7α-diacetoxi-14-hidroxidolasta-1(15),8-dieno. Posteriormente, se evaluaron los efectos en diferentes concentraciones del extracto bruto en gametos y del extracto bruto y dolastano en cigotos del erizo de mar Lytechinus variegatus. Los resultados sugieren que cuando los gametos son expuestos al extracto bruto se promueve una disminución en las tasas de fecundación, 10 a 30% (espermatozoides) y de 20 a 70% (óvulos). Además, cuando los cigotos fueron expuestos al extracto bruto se inhibió el desarrollo en un 86,7% ± 1,6 (250 µg mL-1) y se generaron cigotos anormales que variaron entre 39 y 50%. Los resultados de los experimentos con el dolastano no mostraron evidencias de inhibición del desarrollo embrionario. Sin embargo, se constató la inducción de anomalías y en las mayores concentraciones (25 y 50 µg mL-1) se registró el evento de lisis en los cigotos.

The ability of crude extracts of the brown seaweed Spatoglossum schröederi to counteract some of the biological activities of Lachesis muta snake venom was evaluated. In vitro assays showed that only the extract of S. schröederi prepared in ethyl acetate was able to inhibit the clotting of fibrinogen induced by L. muta venom. On the other hand, all extracts were able to inhibit partially the hemolysis caused by venom and those prepared in dichloromethane or ethyl acetate fully neutralized the proteolysis and hemorrhage produced by the venom. Moreover, the dichloromethane or ethyl acetate extracts inhibited the hemolysis induced by an isolated phospholipase A2 from L. muta venom, called LM-PLA2-I. In contrast, the hexane extract failed to protect mice from hemorrhage or to inhibit proteolysis and clotting. These results show that the polarity of the solvent used to prepare the extracts of S. schröederi algae influenced the potency of the inhibitory effect of the biological activities induced by L. muta venom. Thus, the seaweed S. schröederi may be a promising source of natural inhibitors of the enzymes involved in biological activities of L. muta venom.

Four extracts from the marine red alga Plocamium brasiliense (Greville) M.A.Howe & W.R.Taylor were prepared to identify and characterize their potential allelopathic effects on seed germination, radicle elongation and hypocotyl development of the weeds Mimosa pudica L. and Senna obtusifolia (L.) Irwin & Barneby. The four extracts were prepared in a sequence of solvents of increasing polarity: n-hexane, dichloromethane, ethyl acetate and ethanol/water (7:3). The germination bioassay was carried out at 25 °C with a 12 h photoperiod and the radicle elongation and hypocotyl development at 25 °C with a 24 h photoperiod. The dichloromethane extract showed inhibitory effects on seed germination of both plants (35 and 14%, respectively, in M. pudica and S. obtusifolia), radical germination (52 and 41.7%, respectively) and hypocotyl development (17.1 and 25.5%, respectively). Given the high sensitivity of this parameter to the potential allelopathic effects and the insufficient number of references found in the literature, these results are expected to stimulate new tests with other species of marine algae. Given the high sensitivity of the method for the detection of allelopathic potential, the species P. brasiliense emerges as a possible source of allelopathic substances against weed species. The results are attributed to the chemical composition, especially in relation to the presence of halogenated monoterpenes.

Courtship and fertilization processes and embryonic development of Antennarius striatus were observed under controlled conditions after the capture of two adult specimens in Bahía Gaira (Santa Marta - Colombian Caribbean). The objective was to describe the reproduction mechanisms as well as the different stages of embryonic development, to characterize the behavior and diagnostic features of this species in its first life stages, useful for ichthyoplankton samples identification. Some of the more important events that happened during these processes were: 1) change of coloration, 2) male dance previous to fecundation, and 3) death of the female. Soon after egg-laying, samples were taken periodically; meristic and morphometric data were taken from eggs and larvae. Egg diameter ranged between 566 and 586 μm and notochordal length varied between 1169 and 1252 μm. Estimated time of development from gastrula to early postlarvae for this species is 122 HPF

Se efectuó la observación de los procesos de cortejo, fecundación y desarrollo embrionario de Antennarius striatus, fenómenos que se presentaron bajo condiciones controladas luego de la captura de dos ejemplares adultos en la región de bahía Gaira (Santa Marta - Caribe colombiano). El objetivo fue describir los mecanismos de reproducción y los diferentes estadios del desarrollo embrionario encontrados en este caso de estudio, con el fin de aportar características diagnósticas y de comportamiento de esta especie en sus primeros estadios de vida, útiles en los estudios de identificación de ictioplancton. Las observaciones de los adultos se realizaron directamente a través de un acuario; algunos de los eventos que ocurren durante este proceso son: 1) cambio de coloración, 2) danza del macho antes de la fecundación y, 3) muerte de la hembra. Luego del desove se tomaron muestras periódicamente, a las cuales se les realizaron diferentes medidas de morfometría y merística tanto a huevos como a larvas. El diámetro de los huevos osciló entre 566 y 586 μm y la longitud notocordal de las larvas, entre 1169 y 1252 μm. El tiempo estimado de desarrollo desde el estadio de gástrula a una postlarva temprana es de 122 HPF para esta especie