Animal Molecular Breeding, 2024, Vol.14, No.6, 354-361 http://animalscipublisher.com/index.php/amb 356 Figure 1CBD103gene expression in North American gray wolves (Adopted from Johnston et al., 2021) Image caption: (A) Coat color polymorphism in North American gray wolves in Yellowstone National Park, in which coat color can be gray or black (photo credit Dan Stahler/National Park Service photo). Black coat color is dominantly inherited, conferred by a 3 base pair coding deletion in CBD103. (B) CBD103 expression, relative to expression in dog testis, across tissues of a recently deceased pregnant female Kyy wolf. Error bars represent standard errors across RT-qPCR replicates (2–3 replicates per tissue). A single tissue sample was collected for each tissue except fetus and placenta, which each represent 2 tissue samples (i.e., from 2 fetuses). (C) Absolute expression of annotated beta defensins in epidermal keratinocytes (N = 23), fibroblasts (N = 6), and whole blood (N= 25) from North American gray wolves. Only CBD103 is highly expressed in keratinocytes (Adopted from Johnston et al., 2021) 3.2 Functional implications of TLRgenes in coyotes While specific studies on TLRgenes in coyotes are limited, insights can be drawn from related species and general TLR functionality. TLRs play a crucial role in recognizing pathogens and initiating immune responses. For instance, in other wild species, TLR genes exhibit significant polymorphism, which is maintained by pathogen-mediated selection. This polymorphism influences disease susceptibility and immune responses, as seen in studies on roe deer where TLR2 polymorphism is shaped by antagonistic selection pressures from different pathogens (Quéméré et al., 2021). Similar mechanisms are likely at play in coyotes, where TLR gene variability could influence their ability to respond to diverse pathogen challenges in their environment. 3.3 TLRgene adaptations in domestic dogs Domestic dogs have undergone significant genetic adaptations during domestication, including changes in TLR genes. Whole-genome sequencing of African dogs has revealed positive selection in genes linked to immunity, such as ADGRE1, which provides protective host defense against Plasmodium infections. This gene is also associated with severe malaria resistance in humans, highlighting the role of TLR-related genes in adapting to tropical environments (Liu et al., 2018). Additionally, structural variations in the dog genome, including insertions and deletions, have been linked to immune system functions, further illustrating the impact of domestication on TLRgene adaptations (Wang et al., 2018). 4 TLRGenes and Disease Resistance in Canids 4.1 Role of TLRs in bacterial and viral infections Toll-like receptors (TLRs) are crucial components of the innate immune system, recognizing pathogen-associated molecular patterns (PAMPs) and initiating immune responses against a variety of pathogens, including bacteria and viruses. TLRs such as TLR2, TLR4, and TLR7 have been shown to play significant roles in the immune
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