Do bacteria mutate randomly, and acquire antibiotic resistance, or do they mutate when exposed to antibiotics?

A post from The Conversation reminds us of the classic experiments conducted by Salvador Luria and Max Delbrück, who showed, in 1943, that bacteria mutate randomly, producing antibiotic-resistant organisms without exposure to the antibiotics. See the Wikipedia article on this Nobel prize winning research.

Thanks for reading!

Sunspots 889

Things I have recently spotted that may be of interest to others*:

Politics: The Conversation writes that school hardening isn't very effective.

Science: CNN reports on a male mastodon, who was killed by another one, and also reports that study of the killed mastodon has enabled scientists to study migration patterns in these extinct animals.

The Scientist reports that scientists have been able to find Arthropod (insects, spiders, etc.) DNA in tea bags. Much of this probably was left on the tea leaves when insects bit into the leaves.

Nature discusses the Long-Term Evolution Experiment, which has tracked about 40,000 generations of bacteria (so far), and has found some interesting things, most prominently that mutation has led to a new ability to get energy from citrate.

Gizmodo reports that isolated populations of polar bears have been identified in Greenland.

*I try not to include items that require a password or fee to view.

Thanks for reading.

Mutation produces a new enzymatic function - evolution of new traits

Some people claim that mutations can only cause the loss of function, not the addition of new functions. However, in an exceptionally well-designed experiment, using thousands of generations of Escherichia coli bacteria, Lenski and co-workers have been able to observe a new function appear, by which E. coli can use citrate as an energy source (which normal E. coli cannot do). See here for more on this experiment and the results.

This is not a new result, but it seemed wise to point toward it again in this blog. Thank you for reading!

Sunspots 869

Things I have recently spotted that may be of interest to others*:

Christianity:  (sort of) Christianity Today on Jerry Falwell, Jr.'s, hypocrisy, and sin.

A church in Oregon has filed a lawsuit, complaining that feeding the hungry and homeless is a right under freedom of religion. (They have been doing that for years.)

Environment:  Gizmodo reports that QAnon followers have attacked a butterfly sanctuary.

ListVerse shows us videos of 10 areas that are, scenically, on a par with the National Parks.

Health: NPR reports that Malawi, and perhaps some other poor countries in Africa, have mostly beaten COVID, and how this has happened.

Politics: Christianity Today reports that Florida's governor DeSantis is taking action to present charitable groups from helping care for migrant children, which action is legal in the US (including Florida).

Science: The Scientist reports that mutation rates of especially important genes are lower than for genes in general.

Gizmodo reports that peat bogs in the UK, which are a source of archaeological material, are being lost to global climate change.

Gizmodo also reports on all-female termite colonies.

The graphic used in these posts is from NASA, hence, it is free to use like this.

*I try not to include items that require a password or fee to view.

Thanks for reading.

"We don't have a single example of a mutation resulting in a net gain of information. Not one" (But we do)

The title of this post quotes Eric Metaxas, and is part of a post, by him, on BreakPoint: "We don't have a single example of a mutation resulting in a net gain of information. Not one."

I appreciate Mr. Metaxas. I have read a couple of excellent books by him, and have previously posted about his writing, here and here. However, Mr. Metaxas, who has many gifts, and has done a great deal of good, is not an expert in genetics. He seems to be repeating a statement that he has heard from the Discovery Institute, an organization which argues that mutations did not bring about new functions in organisms. Please note that it is always possible to argue that any difference, however small, between two organisms is the result of God's specific miraculous intervention, and this cannot be experimentally disproved. (It has not been proved, either, and probably couldn't be, even if true.) But it can be doubted, and alternative mechanisms for the rise of new genetic information have been found.The Discovery Institute promotes the idea that God has, indeed, caused all changes in the DNA of two related species, because random changes cannot produce new functions. However, most scientists, Christian and otherwise, believe that most, or all, of such differences have come about through random mutation, followed by selection. Many Christian scientists believe that God has allowed random mutation and selection to exist, as a means of bringing about the diversity of organisms present on earth.

I'm not completely clear as to what Mr. Metaxas means by information. That is a complex subject, and different experts define it in different ways. But it seems clear that he is claiming that living things have never added a function as a result of a mutation. Sorry, but we do have such examples.

The first comment on Mr. Metaxas's post proposes that frameshift mutations have been a common means for the arrival of new functions, and provides a URL, which leads to this article, which is quite technical. The article claims that searching the genome of mice and humans has led to the discovery of several hundred genes that must have arisen by this type of mutation. The first two sentences of this article (after the abstract) are as follows:
"Several mechanisms, such as exon shuffling and alternative splicing, are responsible for novel gene functions, but they generate homologous domains and do not usually lead to drastic innovation. Major novelties can potentially be introduced by frameshift mutations and this idea can explain the creation of novel proteins."
The authors, then, believe that there are "several" mechanisms for the origin of novel gene functioning, including frameshift mutations.

The matter of the rise of new information has been discussed, in six posts in the BioLogos forum, by Dennis Venema. I briefly summarize these posts:
In the first, Venema discusses the position of the Discovery Institute, and the Intelligent Design Movement, and is related to the second paragraph of this post.
He says: "... describing how specified information can arise through natural means does not in any way imply God’s absence from the process. After all, natural processes are equally a manifestation of God’s activity as what one would call supernatural events."

In the second post, Venema describes the Long-Term Evolution Experiment. During this experiment, a colony of sexually reproducing bacteria experienced a mutation which allowed them to use citrate as an energy source, when, prior to that mutation, or series of mutations, they had not been able to do so.

In the third post, Venema discusses evidence that genes for hormone receptor proteins developed, in vertebrates, from duplication, and subsequent alteration, of an ancestral gene.

The fourth post argues, with evidence, that even the DNA responsible for complexly folded proteins may change so that a new function comes about, and that this has happened many times.

In his fifth post, Venema summarizes evidence that the entire vertebrate genome was duplicated, in an ancestor in the distant past, and that some of the "extra" copies of the genes thus formed have gone on to be responsible for new functions in vertebrates:
"This evidence is a strong indication that the modern vertebrate genome went through two rounds of [Whole Genome Duplication] early in its evolution, and that these events provided substantial 'raw material' for the acquisition of new information through gene divergence and neofunctionalization."

In his sixth, and last, post, Venema discusses the differences between the genes of humans and our closest relatives, the chimpanzees.

Thanks for reading. Mr. Venema, nor I, doubt that God is able to create, and change His creations, by any way He sees fit, including the miraculous. However we, and many other Christian scientists, believe that God designed the world so that random mutations, of various types, and natural selection, have given rise to much of the variety that is found in God's good creation. The assertion by Mr. Metaxas that forms the title of this post does not stand up the the evidence.

Added April 8, 2016: A later post on this blog refers to two other examples of recently arising functional genes.

describing how specified information can arise through natural means does not in any way imply God’s absence from the process. After all, natural processes are equally a manifestation of God’s activity as what one would call supernatural events. - See more at: https://biologos.org/blogs/dennis-venema-letters-to-the-duchess/evolution-and-the-origin-of-biological-information-part-1-intelligent-design#sthash.baHk5Eyt.dpuf

describing how specified information can arise through natural means does not in any way imply God’s absence from the process. After all, natural processes are equally a manifestation of God’s activity as what one would call supernatural events. - See more at: https://biologos.org/blogs/dennis-venema-letters-to-the-duchess/evolution-and-the-origin-of-biological-information-part-1-intelligent-design#sthash.baHk5Eyt.dpuf