Abstract
In this thesis, the principles of molecular evolution and phylogeny are introduced in Chapter 1, while the subsequent chapters deal with the three topics mentioned in the title. Part I: Birds, reptiles and mammals are Amniota, organisms that have an amnion during their embryonal development. Even though these organisms have been studied for centuries, their interrelationships remain debated in some cases. In Chapter 2, the molecular phylogenetic position of the egg-laying mammals (Monotremata) is analysed, and Chapter 3 presents an example of rare genomic changes - in this case deletions in protein-coding DNA - that are very useful to distinguish relationships between the orders of placental mammals. Part II: The molecules that constitute the eye lens are stable, transparant proteins termed crystallins. In this part we report some typical examples of the origin and molecular evolution of the vertebrate eye lens crystallins. We present the (-crystallin genes from the platypus (Chapter 4) and the discovery in this species of a novel lens protein, upsilon-crystallin, which turns out to be overexpressed lactate dehydrogenase A (Chapter 5). We further present a paper on the evolution of regulatory sequences of the (B-crystallin gene, which are located in the bidirectional promoter between the head-to-head arranged (B-crystallin and HspB2 genes (Chapter 6). The (-crystallins originated evolutionarily from the family of small heat shock proteins. Some data about the evolution of this protein family in vertebrates and lower chordates are included in General Discussion and Summary (Chapter 8). Part III: Chapter 7 addresses the evolutionary aspects of the mammalian prion protein and touches on the evolution of the prion protein gene family. Specifically, the evolution of a repeat region in the vertebrate prion is discussed. The remarkable finding of a deviating prion gene in the squirrel is presented in General Discussion and Summary (Chapter 8).
