Physiological and morphological responses to simultaneous cold exposure and parasite infection by wild‐derived house mice

Abstract

Summary 1.Many animals respond to environmental demands with phenotypic plasticity of morphology and physiology. We examined the effects of ambient temperature and parasitism on morphology and physiology of wild-derived house mice ( Mus musculus ) that were exposed to cold and/or experimentally infected with a naturally occurring intestinal nematode ( Heligmosomoides polygyrus ). 2. Parasitized mice had changes in some organ masses, decreased ability to digest food, and lower rates of glucose transport but similar total glucose transport capacity as unparasitized mice. Wild-derived house mice did not use fat stores to respond to parasitism but did increase mucosal mass in the small intestine enough to maintain glucose acquisition at a similar level to unparasitized mice. 3. Cold-exposed mice showed increased masses of some organs, lower rates of glucose transport but similar total capacity to transport glucose as warm acclimated mice. 4. The effects of cold exposure and parasite infection were largely independent of each other for the morphological and physiological parameters we measured. 5. The more recent exposure of wild-derived house mice to fluctuating temperatures and to parasite infection may help to explain the subtle differences that we observed in how wild-derived mice respond to environmental demands compared to their laboratory mouse counterparts.

Morphological plasticity varies with duration of infection: evidence from lactating and virgin wild-derived house mice (Mus musculus) infected with an intestinal parasite (Heligmosomoides polygyrus;Nematoda)

“…Ingesta may have been passed through the small intestine more quickly (perhaps using more frequent peristalsis) for parasitized than unparasitized mice and thereby contributed to changes in mass of the serosal layer throughout the entire small intestine. Indeed, wild-derived house mice infected with H. polygyrus can have a slight (2%) but significantly diminished ability to digest food (but see present study; Kristan and Hammond, 2003), which is consistent with faster passage of food through the gut. The effect of H. polygyrus on host food passage time remains to be tested.…”

“…increased small intestine mass; Hammond et al, 1994Hammond et al, , 1996Kristan, 2002) would be diminished in parasitized mice because energy normally used to respond to lactation would be diverted to respond to parasitism. H. polygyrus infection in wild-derived mice is associated with a diminished digestive efficiency and decreased rate of glucose transport by the small intestine (Kristan and Hammond, 2003). Therefore, energy demands on the host during H. polygyrus infection are measurable and have the potential to be substantial enough to affect energy needed for lactation unless mice can increase energy acquisition enough to meet both demands.…”

Effects of life‐history traits on parasite load in grey squirrels

“…intestinal tract, spleen and liver) increase while energy (fat) stores decrease in response to helminth infection thereby resulting in similar body masses but different body compositions for parasitized and unparasitized individuals (e.g. Kristan & Hammond, 2000, 2003; Schwanz, 2006). While our data allow us to exclude increases of spleen mass as a factor affecting the body condition index and there is evidence that body mass is a good predictor of body fat in squirrels (Becker, 1992; Humphries & Boutin, 1996) we cannot reject the possibility that other organs or fat stores were also affected.…”

Ecophysiology of mammals

“…Similar to predator-prey relationships, mammals are involved in host-parasite relationships (always as the host), and research continues on the associated physiological costs of parasitism (Schwanz 2006;Olifiers et al 2015;Simpson et al 2016), and how this might change throughout the year (Kristan and Hammond 2003;Cizauskas et al 2015). Some work on immune function, mostly in regard to parasites, has also been conducted recently, including models of immune function (Garnier et al 2013;Jolles et al 2015), host-parasite interactions (Lopez-Romero et al 2015;Zhang et al 2017), and how social factors affect immune function (Flies et al 2016).…”