MHC genes and oxidative stress in sticklebacks: an immuno-ecological approach

Abstract

Individual variation in the susceptibility to infection may result from the varying ability of hosts to specifically recognize different parasite strains. Alternatively, there could be individual host differences in fitness costs of immune defence. Although, these two explanations are not mutually exclusive, they have so far been treated in separate experimental approaches. To analyse potential relationships, we studied body condition and oxidative stress, which may reflect costs of immunity, in three-spined sticklebacks that had been experimentally exposed to three species of naturally occurring parasite. These sticklebacks differed in a trait, which is crucial to specific parasite defence, i.e. individual genetic diversity at major histocompatibility complex (MHC) class IIB loci. Oxidative stress was quantified as tissue acrolein, a technique that has been applied to questions of immuno-ecology for the first time. We measured gene expression at the MHC and other estimates of immune activation. We found that fish with high levels of MHC expression had poor condition and elevated oxidative stress. These results indicate that MHC-based specific immunity is connected with oxidative stress. They could, thus, also be relevant in the broader context of the evolution of sexually selected signals that are based on carotenoids and are, thus supposed to reflect oxidative stress resistance.

Heat and immunity: an experimental heat wave alters immune functions in three‐spined sticklebacks (Gasterosteus aculeatus)

“…In the present study, stream sticklebacks showed extremely high respiratory burst activity during the heat wave. Such high levels of respiratory burst activity are potentially harmful for the host itself, as oxygen radicals might lead to increased oxidative stress and self-tissue damage (Kurtz et al 2006(Kurtz et al , 2007.…”

The nutritional background of the host alters the disease course in a fish–myxosporean system

“…Oxidative stress is intimately linked to parasite resistance and fitness (Kurtz et al, 2006) and the removal of these free radicals is achieved through non-enzymatic and enzymatic reactions. The primary enzymatic antioxidant defence system is the glutathione redox system that reduces hydrogen peroxide and lipid hydroperoxides at the expense of oxidizing GSH to its disulfide form (GSSG).…”

Carotenoid intake does not mediate a relationship between reactive oxygen species and bright colouration: experimental test in a lizard

“…This has contributed to the unclear role of ROS as moderators of sexually selected traits, and of carotenoids in countering their systemic effects on health in general and colour in particular (Hartley and Kennedy, 2004;Isaksson et al, 2007). The summed negative effects of ROS on aspects of immunocompetence have previously been measured (Kurtz et al, 2006), and one study has assessed the effects of lipid peroxidation in the context of sexual signalling (McGraw et al, 2005b). However, not a single study has to the best of our knowledge measured the circulating levels of ROS subsequent to antioxidant treatment and concomitant effects on colouration.…”