快速学习英语免疫细胞如何检测感染.docVIP

How do immune cells manage to sort through vast numbers of similar-looking proteins within the body to detect foreign invaders and fight infections? For immune cells, singling out foreign proteins is like looking for a needle in a?haystack（干草堆）?-- where the needle may look very much like a straw, and where some straws may also look very much like a needle, notes McGill University physics professor Paul Fran?ois. ? Understanding how immune cells tackle this formidable challenge is important, because it could provide crucial insights into the understanding of immune diseases, from AIDS to auto-immune disorders. ? In a study published May 21 in the journal Physical Review Letters, Fran?ois and McGill graduate student Jean-Beno?t Lalanne used computational tools to examine what kind of solutions immune systems may use to detect small concentrations of foreign antigens (characteristic of potentially harmful infections) in a sea of self-antigens normally present at the surface of cells. ? The researchers computer simulations yielded a surprisingly simple solution related to the well-known phenomenon of biochemical adaptation -- a general biochemical mechanism that enable organisms to cope with varying environmental conditions. ? To find solutions, the computer uses an algorithm inspired by Darwinian evolution. This algorithm, designed previously within the Fran?ois research group, randomly generates mathematical models of biochemical networks. It then scores them by comparing properties of these networks to predefined properties of the immune system. Networks with best scores are duplicated in the next generation and mutated, and the process is iterated over many simulated generations until networks reach a perfect score. ? In this case, almost all solutions found were very similar, sharing a common core structure ormotif（主题，动机）. ? Our approach provides a simpler theoretical framework and understanding of what happens as immune cells sort through the haystack to detect