Effects of ammonia on fertilization, development, and larval survival in the Northern Pacific asteroid, Asterias amurensis.

For developing a complementary test organism to sea urchin during winter in Korea, sensitivities of sperm, embryo, and larvae of Asterias amurensis to un-ionized ammonia were evaluated. The EC50s (Mean ± SD, n = 3) for fertilization and development were 169 ± 62 and 70 ± 19 µg/L, respectively. The 48, 72, and 96-h LC50s for larval survival were 1,674 ± 583, 498 ± 221, and 336 ± 107 µg/L, respectively. The sensitivities of fertilization, development, and larval survival tests with A. amurensis are higher than or comparable to those of sea urchin and other taxonomic groups. Therefore, fertilization, development, and larval survival tests using A. amurensis are suitable for assessing pore water toxicity of marine sediments in Korea.

Effects of the Erika oil spill on the common starfish Asterias rubens, evaluated by field and laboratory studies.

Impacts of the Erika oil spill on the common starfish Asterias rubens were investigated in the field and using laboratory experiments based on contamination via food at different stages of the starfish reproductive cycle. Two months after the shipwreck, levels of hydrocarbons characteristic of Erika fuel were significantly higher in pyloric ceca and body wall of A. rubens from a contaminated site, compared with control animals from an unpolluted reference area. Concomitant immunological responses and detoxification enzyme activity (CYP1A) were enhanced in the impacted starfish, suggesting rapid biotransformation processes. This was confirmed by laboratory experiments which showed a fast PAH uptake during the 10 first days of contamination and the start of biotransformation processes from the third day. Our study confirms benzo(a)pyrene hydroxylase activity (BPH) in A. rubens and demonstrates the influence of CYP1A in the conversion of insoluble PAHs into soluble derivatives in this species for the first time. The rapidity of decontamination could explain why starfish growth, level of motile activity, reproductive investment, energy storage, and larval development were not significantly affected by these contaminants.

[Quantity of functionally changed cells as an identificator of the moment of the organizmus transfer to the next period of development].

As "the threshold gears are peculiar to all processes which are flowing past in the world", the problem of looking up of quantitative criterion determining transition of a biological system from one condition to another, is one of the main problems of natural sciences. For analysis of the given problem we investigated some stages of forwardness of marine aster Asterias rubens (mean and late blastula, early and late gastrula, early larva), dis- tinguishing among themselves by morphological characters. Change of structure of cell populations at each stage of development A. rubens analyzed with the help of method of quantitative assessment of functional condition of cells genome. The method is based on cytophotometryc analysis of cell populations coloured by Feulgen (quantifying of DNA in cell) and Naftol yellow S (quantifying of histones in a cell). As the criterion of estimation of functional condition of the cell was used the parameter CFAGEN, coefficient of functional activity of cell genome deduced from histone/DNA ratio after estimation of the absorbency of the nucleus coloured by two chromophores. The data obtained showed that at the moment of organism transition from one stage of development (late blastula) to another (early gastrula) the difference in CFAGEN values between these stages was statistically authentic. Thus comparison of cell distribution histograms has show that cell population conforming to the early gastrula contains 33 % cells with the level of genome functional activity that differs from this one in the cell population conforming to the late blastula. Just in the same moment, the transition of an organism from the stage of late gastrula to the stage of larva is accompanied by statistically authentic distinction in CFAGEN between these stages and availability of more than 1/3 cells (34 %) of the population at the larva stage showing genome functional activity different from that at the late gastrula stage. Thus, it is established, that the biological system passes to qualitatively new condition, if quantity of members of this system changes (increaser or decreases comparatively to a standard point of reference: the norm, previous system status and etc.) not less than on 1/3.

Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: a small scale perspective.

Sea stars (Asterias rubens L.) were collected in different stations distributed in the Southern Bight of the North Sea. Concentrations of four heavy metals and six PCB congeners were measured in two body compartments (body wall and pyloric caeca). In order to assess the potential harm of these contaminants, two biochemical parameters were measured in sea stars, viz. reactive oxygen species (ROS) production by amoebocytes and cytochrome P450 immunopositive protein (CYP1A IPP) induction in pyloric caeca. Sea stars from stations located in the plume of the Scheldt river showed the highest contamination levels. Other stations, similarly located, displayed lower levels. No simple relationship could be established between ROS production by sea star amoebocytes and contaminant levels measured in sea star tissues. CYP1A IPP induction displayed more contrasted responses, and highly significant regressions were found between PCB concentrations measured in pyloric caeca and CYP1A IPP. Both biological parameters were found to vary significantly over the study area. On the whole, data indicated that contamination levels and subsequent effects in sea stars were comparable to those described in previous large-scale studies, but that working at a smaller scale highlighted the existence of patterns of contamination which can blur general trends due to major contamination sources like contaminated rivers.

Locomotion and righting behavior of sea stars: a study case on the bat star Asterina stellifera (Asterinidae) / Comportamiento de locomoción y enderezamiento en estrellas de mar: un caso de estudio sobre la estrella Asterina stellifera (Asterinidae)

Introduction: The locomotion behavior of an organism involves the integration of aspects like body symmetry, sensory and locomotor systems. Furthermore, various ecological factors seem to be related to locomotion characteristics, such as foraging strategy, migration trends, response to predators and competitors, and environmental stress. Objective: To analyze locomotion and the influence of body symmetry in the crawling and righting movements of the sea star Asterina stellifera. Methods: We carried out laboratory experiments in aquariums in the presence/absence of water current and on a horizontal and vertical surface. Results: The speed is similar to speed in other species of similar size. Both the speed and linearity of displacement were independent of individual body size. A water current leads to faster crawling and straight paths, but there is no rheotaxis: streams do not affect locomotion. Speed and linearity of displacement were independent of individual body size. The displacement pattern described here may be an adaptation of organisms that present dense populations in communities with high prey abundance, as is the case of A. stellifera. Conclusions: Like other asteroids, this species did not show an Anterior/Posterior plane of symmetry during locomotion, or righting movement: it does not tend to bilaterality.

Introducción: El comportamiento de locomoción de un organismo implica la integración de aspectos como la simetría corporal, los sistemas sensorial y locomotor. Además, varios factores ecológicos parecen estar relacionados con las características de la locomoción, como la estrategia de alimentación, las tendencias migratorias, la respuesta a los depredadores y competidores y el estrés ambiental. Objetivo: Analizar el patrón general de locomoción y la influencia de la simetría corporal en la locomoción y enderezamiento de la estrella de mar Asterina stellifera. Métodos: Realizamos experimentos de laboratorio en acuarios en presencia / ausencia de corriente de agua y en superficie horizontal y vertical. Resultados: La velocidad es similar a la velocidad en otras especies de tamaño similar. Tanto la velocidad como la linealidad del desplazamiento fueron independientes del tamaño corporal individual. Una corriente de agua conduce a una velocidad de desplazamiento mayor y a trayectorias más rectas, pero no hay reotaxis: una corriente de agua no afecta el patrón de locomoción. La velocidad y la linealidad del desplazamiento fueron independientes del tamaño corporal individual. El patrón de desplazamiento aquí descrito puede ser una adaptación de organismos que presentan densas poblaciones en comunidades con alta abundancia de presas, como es el caso de A. stellifera. Conclusiones: Al igual que otros asteroides, esta especie no mostró un plano de simetría Anterior / Posterior durante la locomoción o el movimiento de enderezamiento: no tiende a la bilateralidad.

Adhesive papillae on the brachiolar arms of brachiolaria larvae in two starfishes, Asterina pectinifera and Asterias amurensis, are sensors for metamorphic inducing factor(s).

It has been hypothesized by Barker that starfish brachiolaria larvae initiate metamorphosis by sensing of metamorphic inducing factor(s) with neural cells within the adhesive papillae on their brachiolar arms. We present evidence supporting Barker's hypothesis using brachiolaria larvae of the two species, Asterina pectinifera and Asterias amurensis. Brachiolaria larvae of these two species underwent metamorphosis in response to pebbles from aquaria in which adults were kept. Time-lapse analysis of A. pectinifera indicated that the pebbles were explored with adhesive papillae prior to establishment of a stable attachment for metamorphosis. Microsurgical dissections, which removed adhesive papillae, resulted in failure of the brachiolaria larvae to respond to the pebbles, but other organs such as the lateral ganglia, the oral ganglion, the adhesive disk or the adult rudiment were not required. Immunohistochemical analysis with a neuron-specific monoclonal antibody and transmission electron microscopy revealed that the adhesive papillae contained neural cells that project their processes towards the external surface of the adhesive papillae and they therefore qualify as sensory neural cells.

Experimental approaches to evaluating the point of biological system bifurcation.

Any system transforms into a qualitatively new state if the number of its elements changes (increases or decreases in comparison with the standard checkpoint: norm, previous status of the system, etc.) by at least 1/3.