Influences of Domestication and Island Evolution on Dental Growth in Sheep

Funder: Department of Zoology, University of CambridgeFunder: Leverhulme Trust; doi: http://dx.doi.org/10.13039/501100000275Abstract: Domestication and island evolution can lead to changes of life history along the slow-fast gradient. Shifts of life history patterns, in turn, are potentially related to alterations of patterns and timing of tooth eruption. Schultz’s rule predicts an earlier eruption of molars relative to premolars as fecundity increases during the domestication process. On the other hand, evolution on a predator-free, resource limited island might lead to a generally slow life history and delayed tooth eruption, as in the Plio-Pleistocene Balearic caprine Myotragus. In this study, we investigate tooth eruption and its relation to life history in a unique sheep population that is an example of both domestication and island evolution: the ancient and feral Soay sheep (Ovis aries) of the St. Kilda archipelago, Scotland. Tooth eruption timing and sequence is investigated in a comparative framework featuring new data on other domestic sheep (O. aries), including European mouflon (O. a. musimon), as well as wild sheep (O. vignei, O. cycloceros, O. arkal, O. orientalis, O. ammon). These data indicate that the order of eruption is similar in wild and domestic sheep, despite the fundamental life history changes that came about with domestication. However, in contrast to other domestic sheep breeds, Soay sheep erupt their teeth at an absolute older age and also tend to grow more slowly, which resembles the evolutionary trend in island-adapted Myotragus. Despite these similarities, Soay sheep do not share the slow life history pattern inferred for Myotragus, highlighting the distinctive nature of tooth eruption in Soay sheep

<i>Toll-like</i> receptors 2, 4, and 9 expressions over the entire clinical and immunopathological spectrum of American cutaneous leishmaniasis due to <i>Leishmania</i> <i>(V.) braziliensis</i> and <i>Leishmania (L.) amazonensis</i>

<div><p><i>Leishmania (V</i>.<i>) braziliensis</i> and <i>Leishmania(L</i>.<i>) amazonensis</i> are the most pathogenic agents of American Cutaneous Leishmaniasis in Brazil, causing a wide spectrum of clinical and immunopathological manifestations, including: localized cutaneous leishmaniasis (LCL^DTH+/++), borderline disseminated cutaneous leishmaniasis (BDCL^DTH±), anergic diffuse cutaneous leishmaniasis (ADCL^DTH-), and mucosal leishmaniasis (ML^DTH++++). It has recently been demonstrated, however, that while <i>L</i>. (<i>V</i>.) <i>braziliensis</i> shows a clear potential to advance the infection from central LCL (a moderate T-cell hypersensitivity form) towards ML (the highest T-cell hypersensitivity pole), <i>L</i>. (<i>L</i>.) <i>amazonensis</i> drives the infection in the opposite direction to ADCL (the lowest T-cell hypersensitivity pole). This study evaluated by immunohistochemistry the expression of <i>Toll-like</i> receptors (<i>TLRs</i>) 2, 4, and 9 and their relationships with CD4 and CD8 T-cells, and TNF-α, IL-10, and TGF-β cytokines in that disease spectrum. Biopsies of skin and mucosal lesions from 43 patients were examined: 6 cases of ADCL, 5 of BDCL, and 11 of LCL caused by<i>L</i>. (<i>L</i>.) <i>amazonensis</i>; as well as 10 cases of LCL, 4 of BDCL, and 6 of ML caused by<i>L</i>. (<i>V</i>.) <i>braziliensis</i>. CD4⁺ T-cells demonstrated their highest expression in ML and, in contrast, their lowest in ADCL. CD8⁺ T-cells also showed their lowest expression in ADCL as compared to the other forms of the disease. TNF-α⁺showed increased expression from ADCL to ML, while IL-10⁺and TGF-β⁺ showed increased expression in the opposite direction, from ML to ADCL. With regards to <i>TLR</i>2, 4, and 9 expressions, strong interactions of <i>TLR</i>2 and 4 with clinical forms associated with <i>L</i>. (<i>V</i>.) <i>braziliensis</i> were observed, while <i>TLR</i>9, in contrast, showed a strong interaction with clinical forms linked to <i>L</i>. (<i>L</i>.) <i>amazonensis</i>. These findings strongly suggest the ability of <i>L</i>. (<i>V</i>.) <i>braziliensis</i> and <i>L</i>. (<i>L</i>.) <i>amazonensis</i> to interact with those <i>TLRs</i> to promote a dichotomous T-cell immune response in ACL.</p></div