Individual variation in the compromise between social group membership and exposure to preferred temperatures.

Group living is widespread among animal species, and comes with a number of costs and benefits associated with foraging, predator avoidance and reproduction. It is largely unknown, however, whether individuals sacrifice exposure to their own preferred or optimal environmental conditions so they can remain part of a social group. Here, we demonstrate that individual three-spine sticklebacks vary in the degree to which they forego exposure to their preferred ambient temperature so they can associate with a group of conspecifics. Individual fish varied widely in preferred temperature when tested in isolation. When the same individuals were presented with a choice of a warm or cold thermal regime in the presence of a social group in one of the environments, fish spent more time with the group if it was close to their own individually preferred temperature. When a group was in a relatively cool environment, focal individuals that were more social deviated most strongly from their preferred temperature to associate with the group. Standard and maximum metabolic rate were not related to temperature preference or thermal compromise. However, individuals with a higher standard metabolic rate were less social, and so energetic demand may indirectly influence the environmental costs experienced by group members. The reduced tendency to engage with a social group when there is a large difference between the group temperature and the individual's preferred temperature suggests a role for temperature in group formation and cohesion that is mediated by individual physiology and behaviour. Together, these data highlight exposure to non-preferred temperatures as a potential cost of group membership that probably has important but to date unrecognized implications for metabolic demand, energy allocation, locomotor performance and overall group functioning.

Context dependency of trait repeatability and its relevance for management and conservation of fish populations.

Repeatability of behavioural and physiological traits is increasingly a focus for animal researchers, for which fish have become important models. Almost all of this work has been done in the context of evolutionary ecology, with few explicit attempts to apply repeatability and context dependency of trait variation toward understanding conservation-related issues. Here, we review work examining the degree to which repeatability of traits (such as boldness, swimming performance, metabolic rate and stress responsiveness) is context dependent. We review methods for quantifying repeatability (distinguishing between within-context and across-context repeatability) and confounding factors that may be especially problematic when attempting to measure repeatability in wild fish. Environmental factors such temperature, food availability, oxygen availability, hypercapnia, flow regime and pollutants all appear to alter trait repeatability in fishes. This suggests that anthropogenic environmental change could alter evolutionary trajectories by changing which individuals achieve the greatest fitness in a given set of conditions. Gaining a greater understanding of these effects will be crucial for our ability to forecast the effects of gradual environmental change, such as climate change and ocean acidification, the study of which is currently limited by our ability to examine trait changes over relatively short time scales. Also discussed are situations in which recent advances in technologies associated with electronic tags (biotelemetry and biologging) and respirometry will help to facilitate increased quantification of repeatability for physiological and integrative traits, which so far lag behind measures of repeatability of behavioural traits.

Less is more: density influences the development of behavioural life skills in trout.

Theory suggests that habitat structure and population density profoundly influence the phenotypic development of animals. Here, we predicted that reduced rearing density and increased structural complexity promote food search ability, anti-predator response and the ability to forage on novel prey, all behavioural skills important for surviving in the wild. Brown trout were reared at three densities (conventional hatchery density, a fourth of conventional hatchery density and natural density) in tanks with or without structure. Treatment effects on behaviour were studied on trout fry and parr, whereupon 20 trout from each of the six treatment groups were released in an enclosed natural stream and recaptured after 36 days. Fry reared at natural density were faster to find prey in a maze. Moreover, parr reared at natural density were faster to eat novel prey, and showed more efficient anti-predator behaviour than fish reared at higher densities. Furthermore, parr reared at reduced densities were twice as likely to survive in the stream as trout reared at high density. In contrast, we found no clear treatment effects of structure. These novel results suggest that reduced rearing densities can facilitate the development of behavioural life skills in captive animals, thereby increasing their contribution to natural production.

Apical ballooning of the left ventricle: first series in white patients.

BACKGROUND: A cardiac syndrome of "apical ballooning" was recently described, consisting of an acute onset of transient extensive akinesia of the apical and mid portions of the left ventricle, without significant stenosis on the coronary angiogram, accompanied by chest symptoms, ECG changes, and a limited release of cardiac markers disproportionate to the extent of akinesia. Until now, this syndrome has been reported only in Japanese patients. OBJECTIVE: To describe 13 white patients who presented with this syndrome over the previous four years. RESULTS: All but one of the patients were women with a mean age of 62 years. Eight of them presented with chest pain, of whom six had cardiogenic shock. In nine patients a triggering factor was identified: emotional stress in three, trauma in one, pneumonia in one, asthma crisis in one, exercise in two, and cerebrovascular accident in one. In all patients left ventriculography showed very extensive apical akinesia ("apical ballooning") in the absence of a significant coronary artery stenosis, not corresponding with the perfusion territory of a single epicardial coronary artery. Mean maximal creatine kinase MB and troponin rise were 27.4 microg/l (range 5.2-115.7 microg/l, median 16.6 microg/l) and 18.7 microg/l (range 2.0-97.6 microg/l, median 14.5 microg/l), respectively. Six patients were treated with intra-aortic balloon counterpulsation. One patient died of multiple organ failure. On necropsy, no myocardial infarction was found. In the 12 survivors, left ventricular systolic function recovered completely within three weeks. CONCLUSIONS: This is the first series of "apical ballooning" to be reported in white patients. Despite dramatic initial presentation, left ventricle function recovered completely within three weeks in the survivors.

Hepatotoxicity related to itraconazole: report of three cases.

BACKGROUND: The antimycotic synthetic azole compounds are known to lead to toxic liver injury. The occurrence of acute hepatitis is best known for ketoconazole. With itraconazole, hepatotoxic reactions have only very rarely been reported, and histologic data are lacking. We report on three patients who developed acute liver damage during therapy with itraconazole, and in whom liver biopsy specimens were obtained. METHODS: Three patients with apparent itraconazole-induced liver injury were studied. Clinical, laboratory, serologic, and histologic data of all three cases were analyzed. RESULTS: All three patients developed a biochemical-histologic pattern of cholestatic liver injury with damage to the interlobular bile ducts. Beginning ductopenia was present in two, suggesting that itraconazole might be responsible for the occurrence of prolonged drug-induced cholangiopathy. Jaundice was the presenting symptom in all three. It was not accompanied by clinical hallmarks of hypersensitivity, which is suggestive for metabolic rather than for immunoallergic idiosyncrasy. CONCLUSIONS: Itraconazole-induced liver injury presents with a cholestatic pattern of injury with damage to the interlobular bile ducts, possibly leading to ductopenia. We suggest that itraconazole should be added to the list of drugs that may be responsible for a drug-induced vanishing bile duct syndrome. Further histologic documentation in other cases is necessary to strengthen our current findings.