Evolutionary line

Barrett, A.J. and Rawlings, N.D. (2001) Evolutionary lines of cysteine peptidases. Biological Chemistry 382, 727-733. 

Biosimulation may also contribute to better animal models and improved animal data. A better understanding of the basis of disease together with in silico simulations of disease processes and/or drug intervention could lead to better animal models. Developing better animal models includes the need to select appropriate species. In this context, biosimulation could also help find appropriate models down the so-called evolutionary line . 

Zamocky M, Dunand C (2006) Divergent evolutionary lines of fungal cytochrome c peroxidases belonging to the superfamily of bacterial, fungal and plant heme peroxidases. FEBS... 

There were, in other words, two possible reactions to the alimentary crisis produced by dwindling organic sources, and the descendants of the first cells explored both of them, thus giving rise to two divergent evolutionary lines. The interesting thing is that we can reach this conclusion even by a totally different route. 

The appearance of bilateral symmetry (two halves which are mirror images of each other) was an important evolutionary breakthrough. The most primitive bilaterally symmetrical animals are the flatworms (phylum Platyhelminthes). Platyhelminthes gave rise to the coelo-mates, which have a coelom, or internal body cavity. The coelomates split into two evolutionary lines, the proto-stomes (molluscs, annelids, and arthropods) and the deuterostomes (echinoderms and chordates). A few phyla, such as the phylum Bryozoa, are intermediate between the two lines. Of the nearly 20,000 species of bry-ozoans known, only 3,500 are stUl living. 

Comparison of sequences of the same protein in different species yields a wealth of information about evolutionary pathways. Genealogical relations between species can be inferred from sequence differences between their proteins. We can even estimate the time at which two evolutionary lines diverged, thanks to the clocklike nature of random mutations, For example, a comparison of serum albumins found in primates indicates that human beings and African apes diverged 5 million years ago, not 30 million years ago as was once thought. Sequence analyses have opened a new perspective on the fossil record and the pathway of human evolution. 

Fig. 6.1. The Ig chains and their domains. Domains are segments of polypeptide chains, consisting of about 110 amino acids, and have striking similarities in structure and sequence homologies. All chains have an amino-terminal variable domain (V) involved in the recognition of antigen. Some chains have an extra tail piece (tp) or lack the hinge region (hr — ) which confers structural flexibilities on the other heavy chains. Murine IgD, in contrast to human IgD, lack the Q2 domain pointing to an evolutionary divergence in the S gene after the separation of the human from the rodent evolutionary lines (Blattner and Tucker, 1984).

A detailed study of horse hemoglobin has shown that the alpha chains differ from those of human hemoglobin by about 18 amino acid substitutions, as do also the beta chains of the two hemoglobins. If we accept 130,000,000 years as the time that has passed since the evolutionary lines of horse and human separated, as estimated by paleontologists, we conclude that each chain has on the average suffered an evolutionarily effective mutation every 14.5 million years. We may then use this value to discuss other evolutionary epochs. 

Figure 1.11. The three tribes of Fabaceae with quinolizidine alkaloids. The Sophoreae are close to the original stock of all Fabaceae. The more advanced tribes (Phaseoleae, Vicieae, and Trifolieae) are either entirely alkaloid-free or accumulate alkaloids of different origin, as in some species of Phaseoleae, Loteceae, Hedysaraceae, and Galegeae, although more primitive, are without alkaloids of the quinolizidine type. Probably an independent evolutionary line of the Fabaceae evolved which was not directly related to Sophoreae, Genisteae, and Podalyrieae tribes (Nowacki, 1960). Courtesy of the journal.

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