2 resultados para chickens

em Universidade Complutense de Madrid


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From the 1990s, through the first decade of the XXI century, the food industry has intensified its production in technologically and genetically sophisticated ways. It has introduced transgenic and genetically modified foods, taking into account an economical push to obtain higher quantities in less time. Today, the foods that we consume seem more like products created in a laboratory than ones that come from working directly with the earth and with animals. These changes in the food industry are just a part of a long and complicated story in which economical interests figure heavily. The single-crop farming era begins in the 1970s in The United States and Europe. In some regions in Spain having a strong agricultural tradition, small private and family-owned farms that provided food to surrounding populations started disappearing, being uprooted in favor of the creation of large, multi-national companies. The market would expand with the growth of production facilities housing large quantities of animals living numbered and crowded. They mainly house cows, chickens, and pigs from which we obtain different products like milk, eggs and meat. The way these “industrial animals” live today does not even come close to what we think of as a balanced ecosystem, seeing as they are surrounded by machines and by the general use of sophisticated techniques to achieve the best return possible...

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The Major Histocompatibility Complex (MHC) comprises the most polymorphic loci in animals. MHC plays an important role during the first steps of the immune response in vertebrates. In humans, MHC molecules (also named human leukocyte antigens, HLA) were initially regarded as class I or class II molecules. Each of them, presents to different T cells subsets. MHC class I molecules, are heterodimers in which the heavy chain (alpha) has three extracellular domains, two of which (alpha 1 and alpha 2) are polymorphic and conform the antigen recognition sites (ARS). The ARS is thought to be subjected to balancing selection for variability, which is the cause of the very high polymorphism of the MHC molecules. Different pathogenic epitopes would be the evolutionary force causing balancing selection. MHC class I genes have been completely sequenced (α1 and α2 protein domains) and thoroughly studied in Gallus gallus (chicken) as well as in mammals. In fact, the MHC locus was first defined in chicken, specifically in the highly consanguineous variety „Leghorn‟. It has been found that, in the case of chickens the MHC genetic region is considerably smaller than it is in mammals (remarkably shorter introns were found in chickens), and is organized quite differently. The noteworthy presence of short introns in chickens; supported the hypothesis that chicken‟s MHC represented a „minimal essential MHC‟. Until now, it has been assumed that chicken (order Galliformes) MHC was similar to all species included in the whole class Aves...