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The seasquirt Ciona robusta and its co-generic Ciona savignyi , are two long-divergent species, sharing the same habitat and competing for the same spaces and resources. Their very similar morphology has been responsible for the misidentification of the two organisms, and, consequently, for the underestimation of their geographic distributions and new areas of co-occurrence. In spite of the large amount of knowledge built up by developmental biologists, few data are available regarding the morpho-physiology of the two sea squirts. The comparison of morphological and physiological features carried out in the present study (i.e. length-body weight correlation, tunic/organ ratio, tissue-specific retained water and metabolic rate), highlighted slight, but significant, differences strongly supporting the hypothesis of different ecological strategies for the two species. More precisely, C. savignyi invests more energy in growing faster and taller, likely to improve the quality and concentration of the filtered food, and sustains a faster metabolic/growth rate. Conversely, C. robusta invests more into tunic thickness, reducing the risk of predation, even if this likely means a slower metabolic/growth rate. In addition it was noted that in both species, the tunic absorbs more water than the other tissues, a peculiarity that may allow them to better counteract sudden fluctuations in environmental salinity.

This study was designed to investigate the short-term effects of cortisol and 17-beta-estradiol on the intact coronary tree of rainbow trout (Oncorhynchus mykiss). A non-working, isolated, and perfused heart preparation was used. The coronary pressure was monitored together with the coronary flow in order to calculate the coronary resistance. The drug effects were expressed as percent change in coronary resistance. At concentrations higher than 10(-5) mol l(-1), cortisol elicited a significant vasoconstriction (p

There is lack of information concerning species diversification in the Non-Antarctic Nototheniid fish both in relation with their variation in organismal performance and in the morphofunctional characteristics underlying this variation. This work was designed to study in three Sub-Antarctic Nototheniids, Eleginops maclovinus, Patagonotothen tessellata, and Paranotothenia magellanica, cardiocirculatory features that may reflect interspecific differences in organismal performance, which in rum may explain aspects of evolutionary and ecological diversity. Haematocrit values were similar in all three species (between 28 and 3?), being in the range of that observed in other red-blooded Notothenioids. In all species, the heart ventricle was fully trabeculated (Type I ventricle) with P. tessellata and P. magellanica having higher relative ventricle weights than E. maclovinus. The latter species was characterized by unique spindle-shaped ventricle, apparently caused by the insertion of a pair of respiratory muscles on either side of the pericardial cavity. Intrinsic cardiac performance was assessed using an in vitro isolated and perfused heart preparation working under loading conditions. Common trends in the three species were a) the intrinsic heart rate higher than that shown by the Antarctic counterparts, b) stroke volume positively related to preload and inversely to afterload, c) pressure work exhibiting higher cost (in terms of oxygen consumption) than volume work, and d) higher mechanical efficiency under volume loading than under pressure loading. There were clearly defined interspecific differences in cardiac mechanical performance between the two Nototheniinae and E. maclovinus. The heart of the latter differed from those of the Nototheniinae, particularly in its incapacity to maintain constant stroke volume and cardiac output under pressure loading. This finding may be relevant for evaluating organismal performance in light of Notothenioid diversification. (C) 1997 Elsevier Science Inc.

Despite the great interest of Cephalopods in learning studies, behavioral pharmacological experiments using these animals are scanty. The purpose of this study was to find an appropriate method of injection of substances for studying their effects on the behavior of octopuses. We injected into the branchial heart a known volume of seawater to test the effect of cold anaesthesia and of different types of manipulation on the predatory performance of Octopus vulgaris. An injection procedure that is simple, reliable, and does not require anaesthesia is proposed. The article also addresses ethical and manipulation requirements of modern behavioral pharmacology.

1. 1. An in vitro preparation of the intact heart of the frog Rana esculenta was set up. 2. 2. The isolated heart, perfused at constant pressure, was spontaneously beating and able to generate physiological values of output pressure, cardiac output, ventricle work and power. It showed the typical phenomenon of the “hypodynamic state” after a relatively constant time from the onset of the perfusion. 3. 3. Perfusion with air-saturated saline and 99.5% oxygen-saturated saline did not show significant differences in the recorded parameters. 4. 4. This experimental model represents a useful tool for physiological and pharmacological studies, especially when the direct analysis of the effects of hormones, mediators or drugs requires an intact heart preparation.