Below is the entire text of the three links you gave as "proof" that mutations add information. In all the articles all we see are could be's perhapses, may be's. In not a single case do we see an experiment which added a new working gene. In none of the cases do we see a mutation adding additional information. All we see is mutations perhaps replacing existing amino acids to enable the processing of lactose. Note on the first one how exact the changes have to be "Experimental studies suggested that in the 3126 bp coding region those two substitutions were the only mutations capable of increasing activity toward lactose sufficiently to permit growth." There was no new DNA created by these experiments, all they show is that IF (big if) the differences seen between the genes were due to evolutionary mutation, the mutations were favorable. It does not show that new genes were created, that these new genes mutated, that these new genes were added to the genome of the species.
Clearly the articles you refer to do not answer the question, no wonder you did not post the articles where all could see them and instead linked to them hoping no one would look at exactly what they said. Experimental evolution of Ebg enzyme provides clues about the evolution of catalysis and to evolutionary potential.
Hall BG.
Biology Dept., University of Rochester, NY 14627, USA. drbh@uhura.cc.rochester.edu
The ebg (evolved beta-galactosidase) operon of Escherichia coli has been used since 1974 as a model system to dynamically study the evolutionary processes which have led to catalytic efficiency and substrate specificity in enzymes. Wild-type ebg beta-galactosidase, encoded by ebgA, is a catalytically feeble enzyme that does not hydrolyze lactose or other beta-galactosidase efficiently enough to permit growth on those substrates. Each of two specific base substitutions at widely separated sites increases catalytic activity sufficiently to permit growth, and the combination of the two mutations further increases catalytic effectiveness and expands the substrate range of the enzyme in a non-additive fashion. Experimental studies suggested that in the 3126 bp coding region those two substitutions were the only mutations capable of increasing activity toward lactose sufficiently to permit growth. Alignment of EbgA with the LacZ beta-galactosidase showed that both mutations were in active site amino acids. Multiple alignment and phylogenetic analysis of EbgA, LacZ, and 12 other related beta-galactosidases showed that EbgA and LacZ diverged from a common ancestor at least 2.2 billion years ago, that they belonged to different subclasses of the family of 14 beta-galactosidases, that the two subclasses differed at 12 of the 15 active site residues, and confirmed that the two previously identified mutations in ebgA are the only ones that can lead to enzyme with sufficient activity on lactose to permit growth. Studies of the catalytic mechanism of Ebg beta-galactosidase have allowed the widely accepted Albery and Knowles model for the evolution of catalysis to be rejected.
Publication Types:
PMID: 10234816 [PubMed - indexed for MEDLINE]
Determining the evolutionary potential of a gene.
Hall BG, Malik HS.
Biology Department, University of Rochester, New York 14627. drbh@uhura.cc.rochester.edu
In addition to information for current functions, the sequence of a gene includes potential information for the evolution of new functions. The wild-type ebgA (evolved beta-galactosidase) gene of Escherichia coli encodes a virtually inactive beta-galactosidase, but that gene has the potential to evolve sufficient activity to replace the lacZ gene for growth on the beta-galactoside sugars lactose and lactulose. Experimental evidence, which has suggested that the evolutionary potential of Ebg enzyme is limited o two specific amino acid replacements, is limited to examining the consequences of single base-substitutions. Thirteen beta-galactosidases homologous with the Ebg beta-galactosidase are widely dispersed, being found in gram-negative and gram-positive eubacteria and in a eukaryote. A comparison of Ebg beta-galactosidase with those 13 beta-galactosidases shows that Ebg is part of an ancient clade that diverged from the paralogous lacZ beta-galactosidase over 2 billion years ago. Ebg differs from other members of its clade at only 2 of the 15 active-site residues, and the two mutations required for full Ebg beta-galactosidase activity bring Ebg into conformity with the other members of its clade. We conclude that either these are the only acceptable amino acids at those positions, or all of the single-base-substitution replacements that must arise as intermediates on the way to other acceptable amino acids are so deleterious that they constitute a deep selective valley that has not been traversed in over 2 billion years. The evolutionary potential of Ebg is thus limited to those two replacements.
PMID: 9718732 [PubMed - indexed for MEDLINE]
Changes in the substrate specificities of an enzyme during directed evolution of new functions.
Hall BG.
Wild-type ebg enzyme, the second beta-galactosidase of Escherichia coli K12, does not permit growth on lactose. As part of a study of the evolution of new enzymatic functions, I have selected, from a lacZ deletion strain, a variety of spontaneous mutants that grow on lactose and other beta-galactoside sugars. Single point mutations in the structural gene ebgA alter the enzyme so that it hydrolyzes lactose or lactulose effectively; two mutations in ebgA permit galactosylarabinose hydrolysis, while three mutations are required for lactobionic acid hydrolysis. Wild-type ebg enzyme and 16 functional mutant ebg enzymes were purified and analyzed kinetically to determine how the substrate specificities had changed during the directed evolution of these new functions. The specificities for the biologically selected substrates generally increased by at least an order of magnitude via increased Vmax and decreased Km for the substrate. These changes were very specific for the selected substrate, often being accompanied by decreased specificities for other related substrates. The single, double, or triple substitutions in the enzymes did not detectably alter the thermal stability of ebg enzyme.
PMID: 6793063 [PubMed - indexed for MEDLINE]
Ahh yes, the typical Gore3000 tactic of deliberately misrepresenting information. I am left wondering how someone so blatantly dishonest dares to call himself Christian.
Of course they sequenced the DNA, compared the mutants to the wild types and performed the appropriate enzymatic activity assays. The FEMS Micro review article (free on the web) summarizes these studies carried out over the last 20 years on the mutant ebg genes (Table 1, page 2).
In none of the cases do we see a mutation adding additional information.
This is exactly what the study shows. Spontaneous mutations gave rise to those changes within the ebgA gene which were not present in the original population. Spontaneous random mutation changed the information content in a favorable manner – the genetic content (the DNA) changed . The ebgA gene found in the lactose metabolizing bacteria now encodes for an enzyme that can utilize lactose.
We know Gore3000 doesn’t like to read, but for the benefit of everyone else, here is an excerpt from the FEMS review:
How many different genes could evolve to replace the -galactosidase function encoded by lacZ? The answers to several of those questions are now known. Selection for spontaneous lactose utilizing mutants from lacZ ebgR- (constitutive) strains always results in mutations in ebgA [10]; thus within the limits of this experimental system there is only one gene that can evolve to replace lacZ. Among hundreds of independent ebg+ mutants, selection has produced only two classes of ebg+ mutants [10]. Class I mutants grow well on lactose with a first order growth rate constant of 0.4 h-1, while Class II mutants grow more slowly, with a rate constant of 0.2 h-1 on lactose [11]. All Class I mutants have a G to A mutation in ebgA that results in an Asp-92Asn substitution, while all Class II mutants have a G to(T or C) mutation in ebgA that results in a Trp-977Cys substitution [5, 10].
After his rant on how no there were no mutations, Gore3000 clearly contradicts himself in this sentence (referencing the nature of the ebg changes)...
Note on the first one how exact the changes have to be "Experimental studies suggested that in the 3126 bp coding region those two substitutions were the only mutations capable of increasing activity toward lactose sufficiently to permit growth."
So what? Beneficial mutations are rare. But they do occur. In this system several beneficial mutations were observed in different genes controlling the lactose utilization pathway.