Browsing by Author "Negrini, Riccardo"

Now showing 1 - 7 of 7
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    Combining Landscape Genomics and Ecological Modelling to Investigate Local Adaptation of Indigenous Ugandan Cattle to East Coast Fever
    (Frontiers in Genetics, 2018) Vajana, Elia; Barbato, Mario; Colli, Licia; Milanesi, Marco; Rochat, Estelle; Fabrizi, Enrico; Mukasa, Christopher; Del Corvo, Marcello; Masembe, Charles; Muwanika, Vincent B.; Kabi, Fredrick; Stewart Sonstegard, Tad; Huson, Heather Jay; Negrini, Riccardo; Consortium, NextGen; Joost, Stéphane; Ajmone-Marsan, Paolo
    East Coast fever (ECF) is a fatal sickness affecting cattle populations of eastern, central, and southern Africa. The disease is transmitted by the tick Rhipicephalus appendiculatus, and caused by the protozoan Theileria parva parva, which invades host lymphocytes and promotes their clonal expansion. Importantly, indigenous cattle show tolerance to infection in ECF-endemically stable areas. Here, the putative genetic bases underlying ECF-tolerance were investigated using molecular data and epidemiological information from 823 indigenous cattle from Uganda. Vector distribution and host infection risk were estimated over the study area and subsequently tested as triggers of local adaptation by means of landscape genomics analysis. We identified 41 and seven candidate adaptive loci for tick resistance and infection tolerance, respectively. Among the genes associated with the candidate adaptive loci are PRKG1 and SLA2. PRKG1 was already described as associated with tick resistance in indigenous South African cattle, due to its role into inflammatory response. SLA2 is part of the regulatory pathways involved into lymphocytes’ proliferation. Additionally, local ancestry analysis suggested the zebuine origin of the genomic region candidate for tick resistance.
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    Genomic diversity and disease prevalence in Ugandan cattle
    (ReColAd Workshop, 2015) Colli, Licia; Bomba, Lorenzo; Milanesi, Marco; Vajana, Elia; Negrini, Riccardo; Eufemi, Elisa; Capomaccio, Stefano; Mazza, Raffaele; Stella, Alessandra; Joost, Stephane; Stucki, Sylvie; Taberlet, Pierre; Pompanon, François; Kabi, Fred; Muwanika, Vincent; Masembe, Charles; Ajmone Marsan, Paolo
    Ugandan cattle are represented by three main types: the long-horned Ankole, the short-horned zebu, and the Ankole-zebu crosses called “Nganda”. In the course of the EU-funded project Nextgen, Ugandan cattle have been extensively sampled over the whole country to investigate the association between genotypes and resistance/tolerance to endemic diseases (e.g. tsetse fly- and tick-born diseases).
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    Genomic diversity and Population Structure of Ugandan Taurine and Zebuine Cattle Breeds
    (XXI ASPA Congress, 2015) Colli, Licia; Milanesi, Marco; Bomba, Lorenzo; Vajana, Elia; Negrini, Riccardo; Eufemi, Elisa; Capomaccio, Stefano; Mazza, Raffaele; Stella, Alessandra; Joost, Stephane; Stucki, Sylvie; Taberlet, Pierre; Pompanon, François; Kabi, Fred; Muwanika, Vincent; Masembe, Charles; Ajmone Marsan, Paolo
    An extensive sampling of Ugandan cattle was carried out in the course of the European project Nextgen to identify possible associations between geno types, livestock endemic diseases and environmental variables.
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    Geographic distribution of non-clinical Theileria parva infection among indigenous cattle populations in contrasting agro-ecological zones of Uganda: implications for control strategies
    (Parasites & vectors, 2014) Kabi, Fredrick; Masembe, Charles; Muwanika, Vincent B.; Kirunda, Halid; Negrini, Riccardo
    Non-clinical Theileria parva infection among indigenous cattle occurs upon recovery from primary disease during the first year of life. Continuous exposure to infection through contaminated tick infestations with absence of clinical disease gives rise to endemic stability. Endemic stable populations may become sources of infection if contaminated tick vectors are shared with susceptible exotic cattle. This study aimed at establishing a nationwide distribution of non-clinical T. parva infection among indigenous cattle populations to inform novel control strategies. Methods: The occurrence of non-clinical T. parva infection among apparently healthy 925 indigenous cattle from 209 herds spread out in 10 agro-ecological zones (AEZs) was determined using a nested PCR assay. The influence of AEZ, breed, sex, age and farmers’ ranking of ECF importance were interrogated for influence of non-clinical parasite occurrence. Results: The overall prevalence of non-clinical T. parva infection was 30% (278/925). A gradual increase of non-clinical T. parva infection was observed ranging from 17% (95% CI: 0.03 – 0.23) to 43% (95% CI: 0.3 – 0.55) in the North Eastern Savannah Grasslands (NESG) to the Western Highland Ranges (WHR) respectively. A similarly associated 18% (95% CI: 0.07 – 0.28) and 35% (95% CI: 0.3 – 0.39) non-clinical parasite prevalence was observed among the East African shorthorn Zebu (EASZ) and Ankole cattle respectively. Average herd level non-clinical T. parva prevalence was 28%, ranging from zero to 100%. The likelihood of non-clinical T. parva infection was 35.5% greater in the western highlands compared to the northeastern semi-arid AEZs. Conclusions: Non-clinical T. parva occurs countrywide, structured along patterns of AEZ and breed gradients. These findings may guide policy formulation, deployment of integrated control strategies and local cattle improvement programs.
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    Modeling the spatial distribution of Theileriaparva(Theiler 1904), causative agent of East Coast Fever disease in cattle
    (NEXTGEN Consortium, 2015) Vajana, Elia; Colli, Licia; Milanesi, Marco; Bomba, Lorenzo; Negrini, Riccardo; Capomaccio, Stefano; Eufemi, Elisa; Kabi, Fred; Muwanika, Vincent; Masembe, Charles; Ajmone-Marsan, Paolo
    The ileriaparvais a protozoan emo-parasite affecting sub-Saharan Bostaurusand Bosindicuspopulations. It is the causative agent of East Coast Fever, a major cattle disease causing the death of ~1.1∙106 animals per year and an annual loss of ~168∙106USD (Norvalet. al., 1992). T. parvageographical occurrence is bound to the presence of susceptible bovine host populations, the main tick vector Rhipicephalusappendiculatus(Neumann 1901), as well assuitable ecological conditions for the survival of both the vector and the parasite. While tick habitat requirements have been extensively investigated (see e.g. Cumming, 2002), studies focusing solely on the environmental conditions determining the parasite occurrence are still lacking.
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    Patterns of indigenous female cattle morphometric traits variations in Uganda: Evidence for farmers’ selection to enhance agro-ecological fitness
    (Animal Genetic Resources, 2015) Kabi, Fredrick; Masembe, Charles; Negrini, Riccardo; Muwanika, Vincent B.
    Globally, rural cattle keeping communities actively select and breed indigenous cattle to satisfy their interests and enhance adaptation to local landscapes. This study investigated how traditional systems in Uganda have shaped the morphometric population structure of indigenous cattle breeds. Ten linear morphometric traits were interrogated amongst 801 female cattle, comprising 46 Nganda (Bos indicus), 368 Ankole (B. taurus indicus) and 387 East African shorthorn zebu (EASZ, B. indicus). The study cattle were obtained evenly at random from 209 herds in their agro-ecological zones (AEZs) where they have been nurtured by traditional cattle keeping communities throughout Uganda. Age, AEZs and breed significantly influenced the variation of linear morphometric traits exhibiting a gradient of low, intermediate and high dimensions among the EASZ, Nganda and Ankole cattle, respectively. Likewise, the linear morphometric trait (Mahalanobis squared distance) diversity was significantly different exhibiting a gradient of low, intermediate and high variation between Nganda and EASZ, Ankole and Nganda, and Ankole and EASZ cattle, respectively. These findings demonstrate the role of agro-ecological fitness in the evolution of indigenous cattle morphometric population structure in Uganda. The study outcomes further provide a motivation to search for genes associated with the diverse morphometric features
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    SamBada in Uganda: landscape genomics study of traditional cattle breeds with a large SNP dataset
    (n The IALE 2013 European Congress, 2013) Sylvie, Stucki; Orozco-terWengel, Pablo; Colli, Licia; Kabi, Fredrick; Masembe, Charles; Negrini, Riccardo; Bruford, Michael W.; NEXTGEN, Consortium; Joost, Stéphane
    Since its introduction [9], landscape genomics has developed quickly with the increasing availability of both molecular and topoclimatic data. The current challenges involve processing large numbers of models and disentangling selection from demography. Several methods address the latter, either by estimating a neutral model from population structure [3] or by inferring simultaneously environmental and demographic effects [6]. Here we present Sam ada, an integrated software for landscape genomic analysis of large datasets. This tool was developed in the framework of NextGen with the objective of characterising traditional Ugandan cattle breeds using single nucleotide polymorphisms (SNPs) data.