Cytochrome P-450 monooxygenase system and benzo(a)pyrene metabolism in echinoderms

A comparative study on mixed-function oxygenase (MFO) systems was carried out on four echinoderm species: the asteroidsAsterias rubens andMarthasterias glacialis, a holothurianHolothuria forskali and an echinoidEchinus esculentus. Cytochromes P-450 andb ₅ and the MFO system-associated NADH-ferricyanide reductases NADH-cytochromec reductase, NADPH-cytochromec reductase and benzo(a)pyrene (BP) hydroxylase activities were present in microsomal fractions of pyloric caeca ofA rubens andM. glacialis and in the haemal plexus ofH. forskali. In contrast, cytochrome P-450 and BP hydroxylase activity were not detectable in the gonads ofE. esculentus. The tissue and subcellular distribution of the MFO system was studied inA. rubens. MFO system components were found in the stomachs and gonads, although detection of cytochrome P-450 in the latter tissue was difficult. Sex-related differences were not significant. The contents of the MFO system components and BP hydroxylase activities were highest in the microsomal (100 000 ×g) fractions, but MFO system components were also found in the mitochondrial (12 000 ×g) and cytosolic fractions. The BP hydroxylase activity in pyloric caeca microsomes ofA. rubens was NADPH-dependent and was inhibited by several agents known to be inhibitors of vertebrate cytochromes P-450. In the former respect, the characteristics of the MFO system were more like those of vertebrates and crustaceans than that of molluscs.     

A Speaking Piglet Advertises Beef: An Ethical Analysis on Objectification and Anthropomorphism

The portrayal of animals in the media is often criticised for instrumentalising, objectifying and anthropomorphising animals (e.g. Hirschman and Sanders in Semiotica 115(1/2):53–79, 1997; Lerner and Kalof in Sociol Q 40(4):565–586, 1999; Stewart and Cole in Int J Multidiscip Res 12(4):457–476, 2009). Although we agree with this criticism, we also identify the need for a more substantiated approach to the moral significance of instrumentalisation, objectification and anthropomorphism. Thus, we propose a new framework which is able to address the morally relevant aspects of animal portrayal in the media. We closely examine the normative messages communicated by an unusual TV commercial in which an anthropomorphised piglet advertises organic beef. This serves as a case example to relate the philosophical and ethical concepts of objectification and anthropomorphism to each other and show how they can be applied. We conclude that the commercial conveys a message of animal instrumentalisation as being normatively correct within the constraint of good animal welfare. The depicted form of instrumentalisation is, nonetheless, associated with harm for the animals and thus, needs to overcome cognitive dissonance. To achieve this, animals are directly objectified by a trivialised and de-individualised portrayal. Moreover, animals are indirectly objectified even when they are anthropomorphised as they are granted significance only through being human-like. Thus, objectification and anthropomorphism are not opposing terms in our proposed framework. In addition, objectification, together with the reference to the dominant ideology, and combined with humorous anthropomorphism weakens scrutiny of these normative messages by the viewers. This eventually augments a decrease of moral concern for farmed animals in advertisement employing such portrayals.     

Effects of water temperature and mixed layer depth on zooplankton body size

Ecological consequences of global warming include shifts of species ranges toward higher altitudes and latitudes as well as temporal shifts in phenology and life-cycle events. Evidence is accumulating that increasing temperature is also linked to reduced body size of ectotherms. While temperature can act directly on body size, it may also act indirectly by affecting the timing of life-cycle events and the resulting population age and size structure, especially in seasonal environments. Population structure may, in turn, be influenced by temperature-driven changes in resource availability. In a field mesocosm experiment, we investigated how water temperature and mixed surface layer depth (a temperature-dependent determinant of light availability to phytoplankton) affected population dynamics, population age and size structure, and individual size at stage (size at first reproduction) of Daphnia hyalina during and after a phytoplankton spring bloom. Mixed layer depth was inversely related to the magnitudes of the phytoplankton spring bloom and the subsequent Daphnia peak, but had no effect on the body size of Daphnia. Conversely, temperature had no effects on abundance peaks but strongly affected the timing of these events. This resulted in at times positive, at other times negative, transient effects of temperature on mean body size, caused by asynchronous changes in population size structure in cold versus warm treatments. In contrast to mean body size, individual size at stage consistently decreased with increasing temperature. We suggest that size at stage could be used as an unbiased response parameter to temperature that is unaffected by transient, demographically driven changes in population size structure.     

Do wood mice (Apodemus sylvaticus L.) use food selection as a means to reduce heavy metal intake?

Food preference of wood mice from two with heavy metals polluted sites and two unpolluted sites was tested under laboratory and field conditions with two-way choice experiments. In the laboratory, wood mice preferred to eat acorns from unpolluted sites over acorns from polluted sites. Previous experience with polluted food had no influence on food choice. Preference was negatively related to acorn metal content. Furthermore, the nutrient content of the acorn endosperm was consistently lower in polluted sites. We therefore conclude that wood mice used absolute metal concentration in the acorn, nutrient content, or both as a food selection cue. The results of the laboratory experiment could not be confirmed under field conditions. We hypothesized that search time constraints due to the presence of predators, competitors and/or other stress factors in the field have prevented the mice to forage selectively.