Gene Polymorphisms in African Buffalo Associated with Susceptibility to Bovine Tuberculosis Infection

<div><p>Bovine tuberculosis (BTB) is a chronic, highly infectious disease that affects humans, cattle and numerous species of wildlife. In developing countries such as South Africa, the existence of extensive wildlife-human-livestock interfaces poses a significant risk of <i>Mycobacterium bovis</i> transmission between these groups, and has far-reaching ecological, economic and public health impacts. The African buffalo (<i>Syncerus caffer</i>), acts as a maintenance host for <i>Mycobacterium bovis</i>, and maintains and transmits the disease within the buffalo and to other species. In this study we aimed to investigate genetic susceptibility of buffalo for <i>Mycobacterium bovis</i> infection. Samples from 868 African buffalo of the Cape buffalo subspecies were used in this study. SNPs (n = 69), with predicted functional consequences in genes related to the immune system, were genotyped in this buffalo population by competitive allele-specific SNP genotyping. Case-control association testing and statistical analyses identified three SNPs associated with BTB status in buffalo. These SNPs, SNP41, SNP137 and SNP144, are located in the SLC7A13, DMBT1 and IL1α genes, respectively. SNP137 remained significantly associated after permutation testing. The three genetic polymorphisms identified are located in promising candidate genes for further exploration into genetic susceptibility to BTB in buffalo and other bovids, such as the domestic cow. These polymorphisms/genes may also hold potential for marker-assisted breeding programmes, with the aim of breeding more BTB-resistant animals and herds within both the national parks and the private sector.</p></div

Hf isotope evidence for selective mobility of high-field-strength elements in a subduction setting: South Sandwich Islands

176Hf/177Hf isotopes provide information about the behaviour of so-called immobile elements in subduction environments. Early studies of Hf isotopes in subduction zones reached different conclusions regarding the mobility of high-field-strength elements during subduction-related processes. To test the behaviour of Hf during subduction, we have examined the young, intra-oceanic South Sandwich subduction system. Combined 176Hf/177Hf and trace element ratios reveal that Hf may behave as both immobile and mobile, depending upon the exact spatial relationship of the arc volcano to the slab. Throughout most of the arc, magmas show no detectable Hf transfer from the slab to the wedge, perhaps because enrichment of the wedge took place by Hf-deficient, fluid-dominated processes. On the basis of ΔεNd values, which describe the Nd isotope deviation from a local MORB-OIB array, we can discern that northern volcanoes of the arc require a source enriched by fluids that originated from the oceanic crust, whereas southern arc volcanoes have a source modified by a higher proportion of sediment-derived fluids. However, close to the southern slab edge and in rear-arc settings, arc magmas were derived from a source that had undergone Hf addition; we attribute this to element transfer via partial melts from sediment. This implies that Hf mobility from the slab is possible where temperatures are sufficiently high to induce sediment melting rather than fluid generation alone. The implication of this work, for the majority of the arc, is that sediment-derived fluids contribute to magmatism and that sediment-derived melt does not