Differences on the level of hepatic transcriptome between two flatfish species in response to liver cancer and environmental pollution levels.

Environmental factors can cause cancer in both wild animals and humans. In ecological settings, genetic variation and natural selection can sometimes produce resilience to the negative impacts of environmental change. An increase in oncogenic substances in natural habitats has therefore, unintentionally, created opportunities for using polluted habitats to study cancer defence mechanisms.

Age-dependent expression of cancer-related genes in a long-lived seabird.

Studies of model animals like mice and rats have led to great advances in our understanding of the process of tumorigenesis, but this line of study has less to offer for understanding the mechanisms of cancer resistance. Increasing the diversity of nonmodel species from the perspective of molecular mechanisms of natural cancer resistance can lead to new insights into the evolution of protective mechanisms against neoplastic processes and to a wider understanding of natural cancer defense mechanisms. Such knowledge could then eventually be harnessed for the development of human cancer therapies.

Oxidative stress and life histories: unresolved issues and current needs.

Life-history theory concerns the trade-offs that mold the patterns of investment by animals between reproduction, growth, and survival. It is widely recognized that physiology plays a role in the mediation of life-history trade-offs, but the details remain obscure. As life-history theory concerns aspects of investment in the soma that influence survival, understanding the physiological basis of life histories is related, but not identical, to understanding the process of aging.

High feather corticosterone indicates better coccidian infection resistance in greenfinches.

Differential exposure or sensitivity to stressors can have substantial effects on the variation in immune responsiveness of animals. However, the questions about the causes and consequences of these processes have remained largely unclear, particularly as regards wild animals and their natural pathogens. Here we ask how a potential marker of stress responses, the feather corticosterone (CORT) content, reflects the resistance to an experimental infection with natural coccidian parasites in wild-caught captive greenfinches (Carduelis chloris).

Dexamethasone inhibits corticosterone deposition in feathers of greenfinches.

Corticosterone (CORT) content of feathers is a potent source of information about activation of hypothalamus-pituitary-adrenal (HPA) axis during feather growth, which is used for assessment of well-being and stress history of individuals and populations in avian studies. However, little is known about factors affecting deposition of CORT into feathers and how feather CORT covaries with other markers of stress imposed upon individuals during feather growth. We addressed these questions by measuring CORT levels in feathers of wild-caught greenfinches (Carduelis chloris) brought into captivity.

Effects of Endotoxin and Psychological Stress on Redox Physiology, Immunity and Feather Corticosterone in Greenfinches.

Assessment of costs accompanying activation of immune system and related neuroendocrine pathways is essential for understanding the selective forces operating on these systems. Here we attempted to detect such costs in terms of disruption to redox balance and interference between different immune system components in captive wild-caught greenfinches (Carduelis chloris). Study birds were subjected to an endotoxin-induced inflammatory challenge and temporary exposure to a psychological stressor (an image of a predator) in a 2*2 factorial experiment.

On the methodological limitations of detecting oxidative stress: effects of paraquat on measures of oxidative status in greenfinches.

Oxidative stress (OS) is widely believed to be responsible for the generation of trade-offs in evolutionary ecology by means of constraining investment into a number of components of fitness. Yet, progress in understanding the true role of OS in ecology and evolution has remained elusive. Interpretation of current findings is particularly hampered by the scarcity of experiments demonstrating which of the many available parameters of oxidative status respond most sensitively to and are relevant for measuring OS.

Coccidian infection causes oxidative damage in greenfinches.

The main tenet of immunoecology is that individual variation in immune responsiveness is caused by the costs of immune responses to the hosts. Oxidative damage resulting from the excessive production of reactive oxygen species during immune response is hypothesized to form one of such costs. We tested this hypothesis in experimental coccidian infection model in greenfinches Carduelis chloris.

Individual consistency and covariation of measures of oxidative status in greenfinches.

Oxidative stress results from a mismatch between production of reactive oxygen species (ROS) and the organism's capacity to mitigate their damaging effects by building up sufficient antioxidant protection and/or repair mechanisms. Because ROS production is a universal consequence of cellular metabolism and immune responses, evolutionary animal ecologists have become increasingly interested in involvement of oxidative stress as a proximate mechanism responsible for the emergence of trade-offs related to the evolution of life-history and signal traits. Among the most practical problems pertinent to ecological research on oxidative stress is finding a combination of biomarkers of oxidative status that can be applied to typical wild animal models such as small birds, mammals, and reptiles.

Heterophil/lymphocyte ratios predict the magnitude of humoral immune response to a novel antigen in great tits (Parus major).

Animals display remarkable individual variation in their capacity to mount immune responses against novel antigens. According to the life-history theory, this variation is caused by the costs of immune responses to the hosts. We studied one of such potential costs, depletion of somatic resources in wintering wild-caught captive passerines, the great tits (Parus major) by immune challenging the birds with a novel antigen, killed Brucella abortus (BA) suspension.

Carotenoid intake does not affect immune-stimulated oxidative burst in greenfinches.

Carotenoid-based integument colouration is extremely widespread in the animal kingdom. It has been hypothesized that carotenoid colouration is used for communicating the health status of the bearers because carotenoids are efficient immunomodulators or antioxidants. However, the latter argument has been recently debated and the mechanisms by which carotenoids modulate immunity or oxidative balance are poorly known.

Behavioural trait covaries with immune responsiveness in a wild passerine.

Immune system is highly integrated with the nervous and endocrine systems, which is thought to result in covariation between behavioural syndromes and stress- and immune-associated diseases. Very little is known about the associations between behaviour and immune traits in wild animals. Here we describe such an association in passerine birds, the greenfinches (Carduelis chloris).

Effects of chronic leptin administration on nitric oxide production and immune responsiveness of greenfinches.

Leptin and nitric oxide (NO) are both important messengers in intra- and intercellular communication systems in vertebrates. Several studies have demonstrated an involvement of both substances in the immune response. Here we tested the effects of chronic leptin and anti-leptin treatments on the NO production and phytohaemagglutinin- (PHA) induced cutaneous inflammatory response in a wild passerine, the greenfinch (Carduelis chloris).

Effects of carotenoids, immune activation and immune suppression on the intensity of chronic coccidiosis in greenfinches.

Allocation trade-offs of carotenoids between their use in the immune system and production of integumentary colouration have been suggested as a proximate mechanism maintaining honesty of signal traits. We tested how dietary carotenoid supplementation, immune activation and immune suppression affect intensity of coccidian infection in captive greenfinches Carduelis chloris, a passerine with carotenoid-based plumage. Immune activation with phytohaemagglutinin (PHA) decreased body mass among birds not supplemented with lutein, while among the carotenoid-fed birds, PHA had no effect on mass dynamics.

Oxidative stress and information content of black and yellow plumage coloration: an experiment with greenfinches.

Carotenoid and melanin pigments in the plumage of birds are hypothesized to be sensitive to oxidative stress. We manipulated oxidative status of captive greenfinches (Carduelis chloris L.) by the administration of buthionine sulfoximine (BSO), a selective inhibitor of the synthesis of glutathione (GSH), an intracellular antioxidant.

Hematological condition indexes in greenfinches: effects of captivity and diurnal variation.

Ecophysiological research aiming at explaining the causes and consequences of variation in individual condition, health state, and allostasis is traditionally performed on captive animals under controlled laboratory conditions. The question about how captivity per se affects studied parameters is therefore of central importance for generalizing the information gained from such studies. We addressed this question by comparing various indexes of physiological condition of wintering greenfinches sampled in the wild and kept in captivity for different time periods.