Análise genômica estrutural e funcional em bovinos Holandês x Gir infestados pelo Rhipicephalus (Boophilus) microplus

• Autor(a) principal: Pinto, Ana Paula Gomes
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1799
• topic: Bovino de leite; Carrapato; Biblioteca de cDNA; Bioinformática; Bovine milk; Tick; cDNA libraries; Bioinformatics; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS

Rhipicephalus (Boophilus) microplus, the cattle tick, is a hematophagous ectoparasite that causes extensive damage in cattle of tropical and subtropical regions. That are differences in tick resistance between Bos taurus and Bos indicus, but the mechanisms remain poorly understood, despite decades of intensive research. The accomplishment of the present study had as objective: 1) to identify differentially expressed genes that may influence the status resistance/susceptibility to Rhipicephalus (Boophilus) microplus in the skin of Holstein x Gir cattle, 2) to map transcripts derived from two cDNA libraries derived from Holstein x Gir skin infested by ticks, and associate that information with data from a genome scan to detect QTL for resistance to that parasite, 3) to identify SNP and microsatellites markers from EST libraries derived from the cDNA libraries. As non-differentially expressed genes were detected using the Northern Digital technique, a set of 11genes was obtained from the analysis of the functional annotation of the transcripts and their ontological classification. It was possible to observe an up-regulated expression of MGST3, SOD1 and CYB5R1 in susceptible animals in the first 24 hours after infestation and CYB5R1 in the first 48 hours. In resistant animals, was observed an up-regulated expression of CFH and PCOLCE in the first 24 hours after infestation. This gene regulation indicates that the tick infestation induces a complex set of immune responses in the host. The analysis of the transcripts mapped within the QTL confidence intervals associated with resistance to ticks allowed the identification of nine genes (IL-1α, DEFB, DEFB1, DEFB4A, DEFB5, DEFB7, C2C4A, BLA-DQB and CD63) with potential influence on the level of resistance to this parasite. Further studies are needed to validate these genes as candidates. From the pipeline d2cluster/CAP3/MISA, analysis of 1292 unique sequences allowed the detection of 168 microsatellites. Disregarding the monomers, class detected in greatest abundance, success was obtained in the design of 19 primers for EST-SSR, and only five of them refer to the proteins transcribed regions. The mining for identification of SNP in cDNA libraries was carried out from the pipeline RepeatMasker/d2cluster/CAP3/AutoSnp and confirmation of polymorphisms was performed from the manual analysis of the quality file of the sequences. To increase the redundancy of the EST set, the enrichment procedure from sequences deposited in databases was carried out. 10 SNP could be detected from only a contig, this being composed of 27 sequences and have 652 bp. The results obtained in this study and shown in the different chapters are relevant and contribute to more information about the genomic involved in the resistance to cattle tick.