Honolulu Chapter

Archive for February, 2015

 

Enzyme Families–Shared Evolutionary History or Shared Design? A Study of the GABA-Aminotransferase Family

 

Mariclair A. Reeves, Ann K. Gauger, Douglas D. Axe

 

Abstract

 

The functional diversity of enzyme families is thought to have been caused by repeated recruitment events–gene duplications followed by conversions to new functions. However, mathematical models show this can only work if beneficial new functions are achievable by just one or two base changes in the duplicate genes. Having found no convincing demonstration that this is feasible, we previously chose a highly similar pair of E. coli enzymes from the GABA-aminotransferase-like (GAT) family, 2-amino-3-ketobutyrate CoA ligase (Kbl2) and 8-amino-7-oxononanoate synthase (BioF2), and attempted to convert the first to perform the function of the second by site-directed mutagenesis. In the end we were unable to achieve functional conversion by that rational approach. Here we take a complementary approach based on random mutagenesis. Focusing first on single mutations, we prepared mutated libraries of nine genes from the GAT family and tested for BioF2 function in vivo. None of the singly mutated genes had this function. Focusing next on double mutations, we prepared and tested 70% of the 6.5 million possible mutation pairs for Kbl2 and for BIKB, an enzyme described as having both Kbl2 and BioF2 activities in vitro. Again, no BioF2 activity was detected in vivo. Based on these results, we conclude that conversion to BioF2 function would require at least two changes in the starting gene and probably more, since most double mutations do not work for two promising starting genes. The most favorable recruitment scenario would therefore require three genetic changes after the duplication event: two to achieve low-level BioF2 activity and one to boost that activity by overexpression. But even this best case would require about 10^15 years in a natural population, making it unrealistic. Considering this along with the whole body of evidence on enzyme conversions, we think structural similarities among enzymes with distinct functions are better interpreted as supporting shared design principles than shared evolutionary histories.

 

Reeves.

“Just how far some [Obama] administration officials were willing to take the idea that science should override ethical concerns became apparent with the disclosure of a multiyear experiment funded by the National Institutes of Health (NIH) involving more than 1,300 premature infants. As part of the experiment, premature infants were randomly assigned to receive higher or lower levels of oxygen. Those receiving lower levels of oxygen were more likely to die, while those receiving higher levels of oxygen suffered serious eye damage that could lead to blindness. Parents were not informed of the possible increased risk of death for infants enrolled in the study. Nor were most of them informed that researchers recalibrated oxygen equipment to generate false readings, thus preventing medical staff from adjusting oxygen levels based on the individual needs of the infants in their care.

Medical ethicists were appalled. “The word ‘unethical’ doesn’t even begin to describe the egregious and shocking deficiencies in the informed-consent process for this study,” said Michael Carome, MD, the director of the Health Research Group at the nonprofit (and politically liberal) group Public Citizen. “Parents of the infants who were enrolled in this study were misled about its purpose. … They were misled to believe everything being done was in the ‘standard of care’ and therefore posed no predictable risk to the babies.”

via John West has updated Darwin Day in America (read free excerpt!) | Uncommon Descent.

Some of the facts West reveals are astonishing:

“Just how far some [Obama] administration officials were willing to take the idea that science should override ethical concerns became apparent with the disclosure of a multiyear experiment funded by the National Institutes of Health (NIH) involving more than 1,300 premature infants. As part of the experiment, premature infants were randomly assigned to receive higher or lower levels of oxygen. Those receiving lower levels of oxygen were more likely to die, while those receiving higher levels of oxygen suffered serious eye damage that could lead to blindness. Parents were not informed of the possible increased risk of death for infants enrolled in the study. Nor were most of them informed that researchers recalibrated oxygen equipment to generate false readings, thus preventing medical staff from adjusting oxygen levels based on the individual needs of the infants in their care.”

via WORLD | From science to scientism in the Obama era | John G. West | Feb. 7, 2015.

“During its development the nervous system undergoes remarkable changes to attain its complex organization. In order to produce the estimated 1 trillion neurons present in the mature brain, an average of 2.5 million neurons must be generated per minute during the entire prenatal life. This includes the formation of neuronal circuits comprising 100 trillion synapses, as each potential neuron is ultimately connected with either a selected set of other neurons or specific targets such as sensory endings. Moreover, synaptic connections with other neurons are made at precise locations on the cell membranes of target neurons. The totality of these events is not thought to be the exclusive product of the genetic code, for there are simply not enough genes to account for such complexity.”

A Granddaughter Is Born | Counting to God.

The “frog in the endothermic beaker”; sheer objective evil hiding in plain sight:

“Half of Americans think it’s permissible to abort children with mental or physical impairments, according to a 2011 Gallup poll. Pre-born children with diseases diagnosed in the womb are aborted at a high rate. The American Spectator reports that, according to a 2012 review of seventeen international studies, “once prenatal diagnosis is made, anencephaly has an abortion rate of 83 percent and spina bifida of 63 percent.” Another earlier review of twenty studies found that the abortion rate is almost 100 percent for children with spina bifida or anencephaly, 74 percent for Turner syndrome, and 92 percent for Down syndrome.”

Truthbomb Apologetics: Dangerous Thinking.