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Biomedical subjects

Indrek Ots

Publications and source records attributed to Indrek Ots.

5 recordsLinked to original sources
PubMed2006

Antioxidant protection, carotenoids and the costs of immune challenge in greenfinches.

Costs accompanying immune challenges are believed to play an important role in life-history trade-offs and warranting the honesty of signal traits. We performed an experiment in captive greenfinches (Carduelis chloris L.) in order to test whether and how humoral immune challenge with non-pathogenic antigen [sheep red blood cells (SRBC)] affects parameters of individual condition including intensity of coccidian infection, estimates of total antioxidant protection, plasma carotenoids and ability to mount a cell-mediated immune response. We also asked whether the potential costs of immune challenge can be alleviated by dietary carotenoid supplementation. None of the treatments affected intensity of coccidiosis. Humoral immune challenge suppressed the cell-mediated response to phytohemagglutinin (PHA), suggesting a trade-off between the uses of different arms of the immune system. Immune challenge reduced body-mass gain, but only among the carotenoid-depleted birds, indicating that certain somatic costs associated with immune system activation can be alleviated by carotenoids. No evidence for oxidative stress-induced immunopathological damages could be found because immune activation did not affect total antioxidant protection or carotenoid levels. Carotenoid supplementation inclined birds to fattening, indicating that lutein interfered with lipid metabolism. Altogether, our results support the hypotheses of biological importance of carotenoids and exemplify the overwhelming complexity of their integrated ecophysiological functions.

Animals↗
PubMed2006

When not to avoid inbreeding.

Avoidance of incestuous matings is widely reported across many animal taxa, and the adaptive value of such behavior is explained through inbreeding depression. However, an old and somewhat neglected theoretical result predicts that inbred matings offer another, positive effect on the inclusive fitness of parents: an individual who mates with a relative will help that relative to spread genes identical by descent. This benefit can be substantial, if the additional mating achieved by the relative does not harm his mating success otherwise, and in the context of selfing in plants the phenomenon is well known. Here, we develop a model that derives expected values of inbreeding tolerance, that is, the magnitude of inbreeding depression that is required to make individuals avoid inbreeding, for different animal life histories and parental investment patterns. We also distinguish between simultaneous and sequential mate choice, and show that inbreeding tolerance should often be remarkably high in the latter scenario in particular, although egalitarian parental care will lead to lower tolerance. There is a mismatch between theory and data: the almost complete lack of cases where individuals prefer to mate incestuously is at odds with a large overlap between the predicted range of inbreeding tolerance and estimates of inbreeding depression found in nature. We discuss four different solutions to this enigma, and suggest that inbreeding tolerance, where it is found, should not always be attributed to a simple constraint that has prevented finding any other mate.

Animals↗
PubMed2003

Immune response is energetically costly in white cabbage butterfly pupae.

Parasite-driven coevolution has led hosts to develop a complicated and potentially costly defence machinery, consisting mainly of the immune system. Despite the evidence for the trade-offs between immune function and life-history traits, it is still obscure how the costs of using and maintaining the immune function are paid. We tested whether immune challenge is energetically costly for white cabbage butterfly (Pieris brassicae L.) diapausing pupa. Individuals challenged with nylon implant raised their standard metabolic rate nearly 8% compared to the controls. Hence, costs of activation of immune system in insect pupa can be expressed in energetic currency.

Analysis of Variance↗
PubMed2003

Carotenoid-based plumage coloration of male greenfinches reflects health and immunocompetence.

Hypotheses of parasite-mediated sexual selection (PMSS) propose that elaborate male ornaments have evolved due to female preferences. Females would benefit from mating with more ornamental males if males' ornamentation signals their health status and ability to provide parasite resistance genes for the offspring. Carotenoid-based plumage coloration of birds has been hypothesised to honestly reflect an individual's health status due to trade-off in allocation of carotenoids between maintenance and signalling functions. The prediction of this hypothesis, namely that individuals with brighter plumage are able to mount stronger immune responses against novel antigens and reveal generally better health state, was tested in captive male greenfinches (Carduelis chloris). Greenfinches with brighter yellow breast feathers showed stronger humoral immune response against novel antigen (SRBC) while no relationship between plumage coloration and an estimate of cell-mediated immune responsiveness (PHA response) was detected. Elaborately ornamental individuals had better general health state as indicated by the negative correlations between plumage brightness and heterophil haemoconcentration. Consistent with the concept of PMSS, these results suggest that carotenoid-based plumage coloration in greenfinches honestly signals immunocompetence and health status.

Animal Welfare↗