MBIO 4600 Lecture Notes - Lecture 28: Selfish Dna, Antigenic Variation, Gene Duplication
25 Dec 2015
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Document Summary
Hypothesis #1 (cid:1) (cid:1: no selective advantage, dna segmentation and linearization by a selfish dna element resulted in a fully functional genome with a topology that is different, maybe some evolutionary advantage to reassortment of genetic material. Hypothesis #2: subtelomeric recombination-enriched environment for the expression of vlse locus of the antigenic variation system, vary surface antigens through gene conversion persistence in host. Role of genetic modification and exchange in pathogen evolution. Spontaneous mutations: insertions, deletions, single nucleotide exchanges. Recombination: gene duplication, deletion, and rearrangement. Inheritable mutation leading to altered gene function (e. g. activity, regulation, etc. ) Recombination between direct repeats on different molecules: unequal crossing over. One has duplication, one has a deletion. Recombination between direct repeats on the same molecule: looping out (cid:1) (cid:1) Recombination between inverted repeats: results in inversion of promoter sequences. Two antigenically distinct flagellin genes filc (h1 flagellin) and filb (h2 flagellin) that are alternatively expressed.
