Spatially and temporally fluctuating selection at non-MHC immune genes: evidence from TAP polymorphism in populations of brown trout (Salmo trutta, L.)

Abstract

Temporal samples of Danish brown trout (Salmo trutta) from populations representing varying geographical scales were analysed using eight putatively neutral microsatellite loci and two microsatellite loci embedded in TAP genes (Transporter associated with Antigen Processing). These genes encode molecules that are central to the major histocompatibility complex (MHC) class I restricted antigen presentation and thus integral components in the adaptive immune system. As such, they could be influenced by selection, driven by pathogens and parasites in a manner similar to MHC genes. Analysis of allele frequencies at presumably neutral microsatellite loci revealed a temporally unstable population structure within regions, while the population structure was stable over time among regions. Analyses of the two TAP markers indicated an effect of selection at both a regional and micro-geographical spatial scale. Moreover, signals of divergent selection among temporal samples within localities suggest that selection also might fluctuate at a temporal scale. These results suggest that immune genes other than the classical MHC class I and II might be subject to selection and warrant further studies of functional polymorphism of such genes in natural populations.

Isolation over 35 years in a heated biotest basin causes selection on MHC class IIß genes in the European perch (Perca fluviatilis L.)

“…2005), and for non-MHC immune genes, (TAP) in brown trout Salmo trutta (Jensen et al. 2008). However, our analysis is the first to our knowledge indicating that environmental change, in this case most probably heating, may strongly impact the pattern of allele frequency change.…”

MHC class II DQA gene variation across cohorts of brown hares (Lepus europaeus) from eastern Austria: Testing for different selection hypotheses

“…Note that tests involving temporal samples from the same populations are not strictly valid, as they do not represent separate demes. Therefore, we interpreted these outliers as if the temporal samples had corresponded to different populations (see also Hansen et al, 2007;Jensen et al, 2008). We assumed a total of 30 demes.…”

Immunogenetic Factors Affecting Susceptibility of Humans and Rodents to Hantaviruses and the Clinical Course of Hantaviral Disease in Humans

“…It mainly focused on genes of the major histocompatibility complex ( Mhc , equivalent of Hla — human leukocyte antigen —in humans) until the need for more candidate immune target genes had been pointed out [8]. For example, gene candidate approaches related to innate immunity e.g., toll-like receptors or cytokines, [9,10] as well as genomic approaches [11,12,13] have recently been developed on wild birds, fishes and rodents to evaluate the influence of molecular mechanisms on susceptibility to infectious diseases. Investigating spatio-temporal variations of allele/single nucleotide polymorphism (SNP) frequencies at these genes/loci provided further insight into the potential role of these polymorphisms in the susceptibility to infectious diseases [14], the epidemiological consequences of this variability [15] and the evolutionary mechanisms (selection, migration, drift) maintaining immune gene diversity [16,17].…”