Palatability of the tissues of the holothurian Thyone briareus (Lesueur) to fish

The evolutionary adaptations of Thyone briareus (Lesueur) for predator repulsion were investigated. Killifish, Fundulus diaphanus (Lesueur) were fed bite-sized pieces of the integument, gonads, stomach, intestines, longitudinal muscle bands, and retractor muscles of Thyone briareus to determine palatability. Of the tissues tested, gravid ovaries and integument were least palatable to the fish.Noxiousness of the integument and gonads of T. briareus would enhance the survival of sea cucumbers more than noxiousness of other tissues. This indicates that the mechanisms involved in the repulsion of fish predators have evolved as antipredator adaptations.     

Schaubalz und geschlechtliche Auslese beim Kampfl?ufer(Philomachus pugnax)

Ohne ZusammenfassungAus dem Englischen mit freundlicher Genehmigung des Verfassers frei übertragen von H. Culemann, durchgesehen von F. Steinbacher.Observations tending to throw light on the question of sexual selection in birds, including a day-to-day diary on the breeding habits of the Ruff (Machetes pugnax); The Zoologist 1906 und 1907.     

A calcium-stimulated, ouabain-inhibited ATPase in a myocardial fraction enriched with sarcolemma

An active intracellular to extracellular Ca²⁺ efflux has been proposed in heart muscle. A myocardial sarcolemmal ATPase stimulated by an intracellular pCa and serving as a Ca²⁺ pump has been postulated. A recently developed myocardial sarcolemmal preparation has not permitter a search for such an enzymatic activity. In these studies, an ATPase has been demonstrated in the sarcolemma which is activated by Mg²⁺, stimulated as the Ca²⁺ is raised to a pCa of 6, and is inhibited by ouabain. These findings suggest a mechanism by which Ca²⁺ within the myocardium may be modulated and thus how the force of contraction may be altered by cardiac glycosides.     

Plasma electrolyte concentrations in captive and free‐ranging African penguins (Spheniscus demersus) maintained with and without dietary salt supplements

African penguins (Spheniscus demersus) are common display animals in North American zoos and aquariums. At present, 43 American Zoo and Aquarium Association (AZA)‐accredited institutions maintain over 700 of these birds. A survey of facilities found that only seven institutions maintain their birds in “saltwater habitats” (natural, brine, or artificial seawater systems), while the remaining institutions provide freshwater habitats. Penguins maintained in freshwater habitats commonly receive dietary salt supplements, though evidence is lacking as to the value of this practice. This study was designed to evaluate the necessity of salt supplementation in African penguins. We report the results of a randomized, 10‐month comparison of plasma electrolytes (Na, Cl, and K) between groups of 10 salt‐supplemented and nonsupplemented birds living in a freshwater environment. The results showed no significant differences between the two groups. An interfacility comparison at the same time points revealed temporal pattern differences in analyte values between the facilities; however, the absolute concentrations did not exceed clinical ranges found in healthy birds. Furthermore, single time‐point comparisons between wild and captive African penguins indicated similar sodium concentrations, while potassium and chloride concentrations varied between groups. Finally, the plasma electrolyte levels in 20 birds remained statistically unchanged after a 60‐day withdrawal from salt supplementation. This study provides experimental evidence that African penguins maintained in freshwater exhibits on a herring‐, capelin‐, and squid‐based diet do not require salt supplementation. In addition to the practical implications regarding the need for salt supplementation for captive birds, the results also have theoretical significance. They provide evidence that penguins do not need to ingest high salt concentrations to remain in electrolyte balance. In this regard, the ion regulatory mechanisms in penguins are similar to those in terrestrial mammals and birds. Zoo Biol 23:397–408, 2004. © 2004 Wiley‐Liss, Inc.