Sunday, July 31, 2011
The United States has just honored two biochemists, an evolutionary biologist, and some other scientist by issuing stamps to commemorate their achievements [American Scientists (Forever)].
Melvin Calvin (1911-1997) is famous for working out an important pathway of carbon fixation known today as the Calvin cycle. This pathway is prominent in photosynthetic bacteria and in chloroplasts. It is often considered to be a fundamental part of photosynthesis, although some workers prefer to maintain the distinction. Calvin won the Nobel Prize in Chemistry in 1961.
Severo Ochoa (1905-1993) received the Nobel Prize in Physiology or Medicine in 1959 along with Arthur Kornberg. Ochoa demonstrated that RNA could be synthesized in vitro using purified RNA polymerase. Later on he helped create synthetic polynucleotides that helped crack the genetic code.
Asa Gray (1810-1888) is best known today as a friend of Charles Darwin and one of the early supporters of evolution in America. He was a botanist at Harvard for most of his career. The website says he "... became the principal American advocate of evolutionary theory in the mid-nineteenth century." I think it would be much more fair to say that Asa Gray was a strong supporter of evolution. He and Darwin had many discussions (by letter) on the mechanisms of evolution.
Thursday, July 28, 2011
Kalliopi Monoyios is a science illustrator who works at the University of Chicago. She's the artist behind Your Inner Fish and Why Evolution Is true. She has a blog called Symbiartic where she writes about the trials and tribulations of
I was especially interested in her recent article about The DNA Hall of Shame.
Confession time. Illustrators are people, too. And by that I mean they bring assumptions to the table at the outset of every project. There’s no avoiding it – no matter how educated and experienced you are, you can’t know it all. That is why it is so critical for researchers and editors to be intimately involved in every draft of the drawings they commission and publish. This may sound like a mega no-brainer, especially if you’re an editor or art director in a field other than in the sciences who is accustomed to working intimately with illustrators to get what you want. But in my experience illustrating two popular non-fiction science books, illustrations are treated as icing on the cake and are glossed over by fact checkers and editors who otherwise comb manuscripts for errors. Illustrating Your Inner Fish is a prime example. The manuscript went through four drafts of revisions with at least two specialized scientific editors. And yet this gaffe made it through:I know exactly how she feels but even multiple expert reviewers won't save you. When we're writing a textbook we take care to review the text and figures together and we pay just as much attention to the figures as we do to the text. For the most recent edition—about to be sent to the printer—the pages were reviewed by me, my coauthor Marc Perry, our developmental editor Michael Sypes (University of Arizona), content reviewer Barry Ganong (Mansfield University), and accuracy reviewers Scott Lefler (Arizona State University) & Kathleen Nolta (University of Michigan). That's six pairs of expert eyes that look at every page.
All the previous editions went through the same intensive review. Nevertheless, the following incorrect figure—originally drawn by me back in 1992— has been published in four books. It wasn't until Barry Ganong looked at it a few months ago that he recognized the error. Can you spot it? It's subtle, and it may only be apparent to experts on DNA structure, but it's an error nevertheless.1
I add it to The DNA Hall of Shame.
1. I'll post the correct version in a few days.
Wednesday, July 27, 2011
MaRS stands for "Medical and Related Sciences." It's a large complex of buildings kitty-corner from where I work, also known as the MaRS Discovery District. Work has now re-started on Phase II—the tallest building in the image below. That image is the view from my building. The Ontario legislature (Parliament Buildings) is just off to the left.
The new building will house dozens of tenants including some research labs associated with my department and our sister departments. The idea is to bring together various researchers in the university community with private companies who might benefit from their research.
When completed, the extra space will make Toronto one of the largest focused centers of medical research in the world. We have MaRS, the University of Toronto, and four major research hospitals within two blocks of one another. In my particular field of biochemistry and molecular biology there are over 200 active research labs with about 500 graduate students in four departments.
I just hope they have a nice cafeteria.
Monday, July 25, 2011
The next Carnival of Evolution (#38) will be posted right here on Sandwalk. You have only one week to submit your best work on evolution—or recommend something you read that just has to be included!
The August 1st carnival is shaping up to be one of the best ever so get your submissions in right now so I can prepare the posting.
There's going to be a surprise category so watch this space next Monday.
Sunday, July 24, 2011
It often seems as though Cornelius Hunter can't read any news article about science without spinning it into an attack on evolution. His latest attempt is a misreading of an article in New Scientist that reminds us of the complexity of some modern bacterial species. According to Hunter this information refutes a major prodiction of evolution [New Scientist: Not so Simple—Bugs That Break all the Rules].
It seems that first born cell of evolution must have been quite complex, including a vast proteome of hundreds of different proteins. This is just one of many scientific falsifications of evolution’s prediction of simple beginnings.Most intelligent people can see the flaws in Hunter's logic so I won't bother pointing them out. However, I would like to highlight the first comment on Hunter's blog. Thorton said ...
We know you hit the bottom of the barrel with your anti-science nonsense some time ago CH. Now we discover your barrel had a trap door.Very clever. And very appropriate. Well said Thorton.
Back in the olden days of talk.origins there was a bright young student named "deaddog" who posted frequently. His speciality was The origin of life.
Deaddog became Professor Andy Ellington at the University of Texas at Austin and he's still interested in the origin of life [The Ellington Lab] and the creation of new life forms [Dr. Andy Ellington].
Deaddog (Andy) has testified before in front of the Texas board of education in an attempt to educate them about science. As you might imagine, given his interests, he concentrated on showing that Jonathan Wells and the IDiots are dead wrong about origin of life research. This is about as hard as shooting fish in a barrel but somebody has to do it.
Last week he was back at the meetings to testify in favor of adopting good biology textbooks. Here's what he said on Andy Ellington's Blog: On the Circus.
Today I’m at the State Board of Education hearings on textbook adoption. Or, in other words, the once every-so-often meeting that helps to determine whether or not Texas makes itself a laughingstock with respect to the teaching of evolution. I guess this is sort of my first “live blog,” which is just weird.This provoked a response from some of the main IDiots like Casey Luskin [University of Texas Evolutionary Biologist Andy Ellington Mocks Fellow Texans as "Idiots" and "Laughingstocks" for Doubting Darwin] and Denise O'Leary [Tax dollar alert: Who pays this Texas biology profs salary?]. Don't you just love it when the IDiots voluntarily supply us with evidence of their reasoning ability?
I continue my love / hate relationship with Texas. On the one hand, this board meeting is democracy in action (not necessarily a good thing in a Republic): every idiot gets their say. On the other, their say means very little. The larger forces at work will drive both curriculum and the impact of that curriculum.
They should have been careful about who they tried to pick on. Here's Andy's response [On Idiocy].
The Discovery Institute, largely a spent force both intellectually and politically since Dover, has chosen to take issue with my comments at the State Board of Education. This is especially amusing as the original disputation of their idiocy came many years ago, and has been published via a NSCE publication for quite some time. Indeed, I refer to this publication in my previous testimony, which was and is available to the Discovery Institute. From this, we can conclude that the Discovery Institute is woefully behind the times not only in terms of science, but even in terms of their own shallow attempts to provide a revisionary context to science. Guys, this just can’t be good for your funding posture. Try to keep up.I miss deaddog.
So, when the DI has a vague, anonymous scientist (apparently the only kind that the DI employs) point out, as they do in their current idiot posting (please note the use of the word ‘idiot,’ as it absolutely applies to the DI for their complete lack of understanding of the extant scientific literature) ...
The DI claims this all as a teachable moment, saying that “What we see evidence of here is a scientific debate over the origin of life ….” No, actually, the problem with that claim is that science for the most part requires experimentation. You guys don’t do experiments. We do. You guys just carp about our experiments, and you don’t even do that very well.
Which would you rather see helping to set policies relating to teaching biology, literally millions of scientists who spend their entire careers doing experiments, or a handful of folks at a faith-based think tank whose jobs largely depend on trying to make inconvenient facts go away?
Well, Casey, I hope this gets your page hit count up somehow. God knows you need it. But really I don’t think that picking a fight about the facts is going to help you guys much in your further, currently grossly unsuccessful attempts to show your relevance. You didn’t even have boots on the ground at the Texas SBOE hearings this time, you just sent a 80 page screed that in the end didn’t change one word in one textbook up for consideration. Sad, really. But, there ya go. Happy trails.
UPDATE: How many have heard that old saying about what you're supposed to do when you've dug yourself into a deep hole?1 Here's a couple of examples of what you're NOT supposed to do. These postings attacked real science and they were the ones that provoked Andy's response. Why do so many non-scientist IDiots think they can successfully debate with an expert in the field?2
Casey Luskin, the lawyer, says Andy Ellington's Citation Bluffs and the Scientific Debate Over the Miller-Urey Experiment
Denyse O'Leary, the jounralist, says Texas school board hearings: Startling gains in the hard science of citation bluffing are now widely noted.
1. Stop digging.
2. It's a rhetorical question. They are IDiots and that's exactly what IDiots do.
Friday, July 22, 2011
Science Daily published a press release from the University of North Carolina School of Medicine: Researchers Identify Seventh and Eighth Bases of DNA. The news was so extraordinary that the article was copied on RichardDawkins.net. Here's the opening paragraphs from the press release ...
ScienceDaily (July 21, 2011) — For decades, scientists have known that DNA consists of four basic units -- adenine, guanine, thymine and cytosine. Those four bases have been taught in science textbooks and have formed the basis of the growing knowledge regarding how genes code for life. Yet in recent history, scientists have expanded that list from four to six.Speaking of textbooks, this amazing discovery couldn't have come at a better time since I'm just wrapping up the final chapters of my introductory biochemistry book. I'd better review what I wrote to see if I can include the 7th and 8th bases. Here's what I've got so far ...
Now, with a finding published online in the July 21, 2011, issue of the journal Science, researchers from the UNC School of Medicine have discovered the seventh and eighth bases of DNA.
These last two bases -- called 5-formylcytosine and 5 carboxylcytosine -- are actually versions of cytosine that have been modified by Tet proteins, molecular entities thought to play a role in DNA demethylation and stem cell reprogramming.
Much is known about the "fifth base," 5-methylcytosine, which arises when a chemical tag or methyl group is tacked onto a cytosine. This methylation is associated with gene silencing, as it causes the DNA's double helix to fold even tighter upon itself.
Last year, Zhang's group reported that Tet proteins can convert 5 methylC (the fifth base) to 5 hydroxymethylC (the sixth base) in the first of a four step reaction leading back to bare-boned cytosine.
DNA and RNA contain a number of modified nucleotides. The ones present in transfer RNA are well known (Section 21.8B) but the modified nucleotides in DNA are just as important. Some of the more common modified bases in DNA are shown in Figure 18.17. Most of them are only found in a few species or in bacteriophage while others are more widespread.Oh dear. Looks like I've made a serious mistake. I've shown bases #5, #6, #7, #8, #9, and #10 but everyone knows that up until yesterday only six bases were known.
We will encounter N6-methyladenine in the next chapter when we discuss restriction endonucleases. 5-Methylcytosine is a common modified base in mammalian DNA because it plays a role in chromatin assembly and the regulation of transcription. About 3% of all deoxycytidylate residues in mammalian DNA are modified to 5-methylcytidine.
Where did I go wrong? Can anyone help me out before I have to send this chapter to the printer?1
(The original Science paper is Ito et al. (2011). The authors really do imply that there are only six known modified nucleotides but they add an important qualifier that seems to have been played down the press release.)
1. One of my sources is Gomers-Apt and Borst (1995). In addition to the modified bases I've shown above they describe three forms of glycosylated hydroxymethyl cytosine (#11, #12, #13), uracil (#14), α-putrescinylthymine (#15), two different sugar substituted forms of 5-dihydroxypentyluracil (#16, #17), a-glutamylthymine (#18), 7-methylguanine (#19), N6-carbamoylmethyladenine (#20), N6-methylcytosine (#21), three versions of glycosylated 5-hydroxycytosine (#22, #23, #24) and β-D-hydroxymethyluracil (#25).
Gommers-Ampt, J.H. and Borst, A.P. (1995) Hypermodified bases in DNA. FASEB 9: 1034-1042 [FASEB]
Ito, S., Shen, L., Dai, Q., Wu, S.C., Collins, L.B., Swenberg, J.A., He, C., and Zhang, Y. (2011) Tet Proteins Can Convert 5-Methylcytosine to 5-Formylcytosine and 5-Carboxylcytosine. Science Published Online 21 July 2011 [doi:10.1126/science.1210597]
Wednesday, July 20, 2011
Sunday, July 17, 2011
Horace Freeland Judson died on May 6, 2011. He is best known as the author of The Eighth Day of Creation first published in 1979 and later re-published in an expanded edition in 1996. This is a "must-read" book for all students of biochemistry and molecular biology.
Mark Ptashne has published an obituary in PLoS Biology [Horace Judson (1931 - 2011)]. Ptashne raises an issue that should be of concern to all biological scientists; namely, the fact that modern molecular biologists seem to be completely unaware of the history of their field and of all the fundamental work done with bacteria and bacteriophage. This was a problem that Judson tried hard to rectify before it was too late but it's beginning to look like he was not successful.
Here's Ptashne's take on it.
The Eighth Day, first published in 1979, is a gift that keeps on giving. It is not the completeness of his history, nor even the vivid prose that imparts its lasting effect. Rather, Judson had the drive and wit to probe until he understood not just who did what, and with what quirks of personality, but why they did it, and how they did it. At each stage he reveals what was at stake, what the crucial alternatives were, and how the problems were solved (or not, as the case may be). Who cares about this past, you might ask, we scientists being neither artists nor composers?Shortly after I read this obituary I was browsing Biology News Net and came across this remarkable opening statement in a press release from Stowers Institute for Medical Research in Kansas City, Missouri, USA.
Could it be that—for scientists as well as composers and artists—the past can be a source of inspiration, and that we ignore it at our peril? Consider the question of how states of gene expression are conveyed from mother to daughters as cells divide. Are instructions passed along by regulatory proteins present in the cytoplasm (so-called “cytoplasmic determinants”), or is the information somehow built into, or attached to, the DNA and transferred along with it? Experiments performed by Francois Jacob and Jacques Monod and their colleagues at the Institut Pasteur in the 1960s distinguish between the models, strikingly supporting the first of these possibilities. These experiments (including the famous “zygotic induction” and “PaJaMa” experiments—see Judson's book) were, of course, performed with bacteria.
I recently spoke with an editor of a major journal that regularly publishes sensational papers on the question as it applies to higher organisms, and learned that s/he, like many of the journal's authors, had never heard of these bacterial experiments! You realize, reading Judson's book, that the challenge is to engage the thought processes of these French scientists, ponder their approaches and results, and design experiments of comparable power and clarity to confirm or refute their conclusions in a different setting. Without that engagement, the new answers are apt to be (and in my opinion usually are) baloney.
Look up “transcription”—the copying of a gene’s DNA into RNA intermediaries—in any old molecular biology text book, and it all seems very simple: RNA polymerase II, the enzyme that catalyzes the reaction, assembles at the start site and starts motoring down the strand, cranking out the RNA ribbon used to construct proteins. But researchers now know that RNA polymerase II often stalls on DNA strands where it was once assumed to just barrel down.This is a very misleading statement. Back in 1989 I wrote an extensive section on "RNA Polymerase Pauses While Transcribing Some Sequences" in my first textbook. I described the effects of sequence and secondary structure on the rate of elongation and explained how a protein component of the the transcription complex (NusA) promotes pausing in order to enhance transcription termination. The idea that rates of elongation were NOT constant was an important part of most molecular biology textbooks.
A report from the Conaway lab at the Stowers Institute for Medical Research in the July 8, 2011, edition of the journal Cell identifies a switch that allows RNA polymerase to shift gears from neutral into drive and start transcribing. This work sheds light on a process fundamental to all plant or animal cells and suggests how transcriptional anomalies could give rise to tumors.
But this was in bacteria (E. coli), where most of these fundamental discoveries were first made. The press release refers specifically to eukaryotic RNA polymerase II. In the second edition of my textbook (1994) I talked about RNA polymerase II elongation factors (eukaryotes) and specifically mentioned that "TFIIS may play a role in pausing and transcription termination that is similar to the role of NusA in bacteria." The point is that older molecular biology textbooks were well aware of the fact that even the eukaryotic transcription elongation complexes did not move at a constant rate. The press release is quite incorrect.
The actual paper is not about transcription elongation but transcription initiation and how various factors assist in the transfer from the initiation complex to the elongation complex. All this was known for transcription in E. coli back in the 1970s. The old molecular biology textbooks explain abortive initiation and how RNA polymerase can stall at initiation sites until sigma factors are replaced by elongation factors. None of that is new in spite of what the press release implies.
How does this happen? I think it's because modern researchers are completely unaware of the history of their field. That's partly because the work on bacteria and bacteriophage—where the basic concepts were often discovered—is no longer taught in biochemistry and molecular biology courses. This leads to the false idea, as expressed in the press release, that all new discoveries in eukaryotes are truly new concepts that nobody ever thought of before.
The solution to this problem is to make all students read The Eighth Day of Creation.
Saturday, July 16, 2011
Friday, July 15, 2011
The National (USA) Center for Science Education (NCSE) has just endorsed a four-year-old statement on teaching evolution from the Canadian Society for Ecology and Evolution [Canadian Society for Ecology and Evolution adds its voice for evolution]. Here's the text from the CSEE website [CSEE/SCEE President's Forum].
There is overwhelming evidence that life has evolved over thousands of millions of years. The ancestors of modern organisms, as well as whole groups that are now completely extinct, have been found in great abundance as fossils. The main processes responsible for evolutionary change, such as variation and natural selection, have been repeatedly observed and verified in natural populations and in laboratory experiments. All the features of living organisms, including those discovered in the recent advances in molecular biology, are readily explained by the principles of evolution. Any scientific theory that provides a clear mechanism, offers a broad explanation of natural phenomena, receives strong support from observation and experiment and that is never refuted by careful investigation is usually called a “fact”. The cell theory of organisms, the germ theory of infection, the gene theory of inheritance and the theory of evolution are all facts. Teaching alternative theories as though they had equivalent scientific status is a perversion of education that damages children’s ability to understand the natural world. In particular, creationism is a religious doctrine long since known to be a fallacious account of Earth history that has no scientific standing and cannot be represented as a credible alternative to evolution. Evolution is the single most important principle of modern biology and the foundation of any sound biology curriculum.I don't like this statement because: (1) it implies that the "theory of evolution" is only about variation and natural selection, (2) it confuses evolutionary theory with the facts of evolution, and (3) it confuses creationism with Young Earth Creationism.
President, Canadian Society for Ecology and Evolution
If you are going to claim that your version of evolutionary theory is correct then you would be well-advised to define it. And if you are going to claim that it's a fact then what's the point of calling it "evolutionary theory"? The "theory" part of evolution is an explanatory model that's used to understand and interpret various facts about the history of life.
With respect to point #3, one of the main threats to science these days comes from Intelligent Design Creationism and there are many IDiots who do not subscribe to an obviously "fallacious account of Earth's history."
Tuesday, July 12, 2011
Denise O'Leary has discovered a paper that was written up in Science
I couldn't make head nor tail of the posting on Uncommon Descent [Most life forms show S pattern in chromosome lengths, guess which one doesn’t?] but that didn't surprise me because, after all, it was written by an IDiot. However, I was a bit surprised by the Science News report because I couldn't understand it either.
So I looked at the original paper. Here's the reference and abstract.
Li, X., Zhu, C., Lin, Z., Wu, Y., Zhang, D., Bai, G., Song, W., Ma, J., Muehlbauer, G.J., Scanlon, M.J., Zhang, M., and Yu, J. (2011) Chromosome Size in Diploid Eukaryotic Species Centers on the Average Length with a Conserved Boundary. Mol. Biol. Evol. 28: 1901-1911. [doi: 10.1093/molbev/msr011]Here's the challenge. Read the abstract and try and guess what important scientific point the authors are making that deserves publication in a molecular evolution journal. For extra points, read the entire article and see if you can improve your guess. You'll be impressed when you read the discussion and it all becomes clear (not!)
Understanding genome and chromosome evolution is important for understanding genetic inheritance and evolution. Universal events comprising DNA replication, transcription, repair, mobile genetic element transposition, chromosome rearrangements, mitosis, and meiosis underlie inheritance and variation of living organisms. Although the genome of a species as a whole is important, chromosomes are the basic units subjected to genetic events that coin evolution to a large extent. Now many complete genome sequences are available, we can address evolution and variation of individual chromosomes across species. For example, “How are the repeat and nonrepeat proportions of genetic codes distributed among different chromosomes in a multichromosome species?” “Is there a general rule behind the intuitive observation that chromosome lengths tend to be similar in a species, and if so, can we generalize any findings in chromosome content and size across different taxonomic groups?” Here, we show that chromosomes within a species do not show dramatic fluctuation in their content of mobile genetic elements as the proliferation of these elements increases from unicellular eukaryotes to vertebrates. Furthermore, we demonstrate that, notwithstanding the remarkable plasticity, there is an upper limit to chromosome-size variation in diploid eukaryotes with linear chromosomes. Strikingly, variation in chromosome size for 886 chromosomes in 68 eukaryotic genomes (including 22 human autosomes) can be viably captured by a single model, which predicts that the vast majority of the chromosomes in a species are expected to have a base pair length between 0.4035 and 1.8626 times the average chromosome length. This conserved boundary of chromosome-size variation, which prevails across a wide taxonomic range with few exceptions, indicates that cellular, molecular, and evolutionary mechanisms, possibly together, confine the chromosome lengths around a species-specific average chromosome length.
Monday, July 11, 2011
Polaris 25 will take place this coming Friday, Saturday, and Sunday (July 15-17) at the Sheraton Parkway Toronto North in Richmond Hill, just north of Toronto. It will celebrate the 45th anniversary of Star Trek. Three of the actors from Stargate SG-1/Stargate Atlantis will be there—that's my favorite TV series (now in re-runs).
The Centre For Inquiry and its Committee for the Advancement of Scientific Skepticism (CASS) has been invited to present a Skeptical Track at the convention. The four speakers are ....
- Me (Larry Moran): "What’s the Difference Between Science and Science Fiction?"
- Jeffrey Shallit: "Misinformation Theory: How Creationists Abuse Mathematics."
- Chris Hassall: "The Evolution of Superstition: People, PCs and Pigeons."
- Alex Manafu: "Could Science Prove the Existence of God? (Or, Must Science Be Naturalistic?)"
Tuesday, July 05, 2011
This month's Carnival of Evolution (37th version) is hosted by William, a 13 year old budding evolutionist who lives in Petawawa, Ontario, Canada [Carnival of Evolution #37-Happy Canada Day!]. His blog is The Lessons of Evolution.
The next edition will be hosted right here on Sandwalk! (Canadians are taking over the world.) Email me if you have posted something on evolution that deserves to be in the next carnival. Or just send me a link if you come across something posted by someone else. (l(dot)moran(at)utoronto(dot)ca)
I even accept postings from adaptationists and (maybe) evolutionary psychologists. I also promise to give serious consideration to postings from (some) philosophers.
There will be a new surprise category in next month's carnival—watch for it!
Today marks the launch of another blog network. This one is The Scientific American Blog Newtork. Bora Zivkovic is the man behind it.
I read about thirty blogs on a regular basis. Some of them have migrated two or three times over the past five years and I always follow them because they are good blogs. I really don't care whether the blogs I follow are part of a network or not. I don't read the other blogs in a network because my aggregator gives me a direct feed.
What's the purpose behind belonging to a blog network? Does it provide something that you can't get by being an independent blogger? Is it money? Are there any downsides other than the fact that you are lending your name to support for a profit making corporation? If you're supporting a magazine like Discover, Seed (now dead), Nature, or Scientific American does it mean that you stand behind whatever they print?
The thing I find most annoying about commercial blogs is the advertising—some of which is contrary to what's being posted. Is the "profit" to the blogger really significant enough? Maybe it is for PZ Myers but the income for someone like me was peanuts when I last explored that option.