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Genes Must Be Expressed in the Right Order

A team of scientists in Switzerland made neural cells switch on a transcription factor earlier during the embryo’s development.  The result?  Axons (long branches of nerve cells) refused to grow to the spinal cord and to the peripheral target.  To the mice, this meant they couldn’t feel things on the skin due to stunted nerves.  […]

Your Linemen at Work: DNA Search and Rescue Machine Imaged in Action

DNA is amazing enough, but its automatic error-correction utilities are enough to stagger the imagination.  There are dozens of repair mechanisms to shield our genetic code from damage; one of them was portrayed in Nature1 March 31 (see also analysis by Sheila David in the same issue2) in terms that should inspire awe.     […]

How to Get Something from Nothing: Genetic Code, Syntax Explained?

Two articles in recent science literature attempt to show that complex entities, like the genetic code and the syntax of human language, are no big deal.  They can emerge from precursors by chance.     In PNAS recently,1 veteran researcher Harold J. Morowitz (George Mason U) and two colleagues proposed a new theory for the […]

Introns Engineered for Genetic Repair

Scientists at Purdue University are using bacterial machines to treat cancer and other diseases.  These machines, called Group I introns, were thought to be useless: Once thought of as genetic junk, introns are bits of DNA that can activate their own removal from RNA, which translates DNA’s directions for gene behavior.  Introns then splice the […]

Selecting Corn Oil Genes Produces More Corn Oil, but What Else?

Breeders have been trying to squeeze more corn oil out of corn for over a century, one of the longest-running scientific experiments ever.  They have made pretty dramatic gains in yield, from 5% to 20%, in 100 generations, says William G. Hill in Science.1  Now also, geneticists have the tools to look for which genes […]

Genes Evolving Downward

Those assuming the evolution of eukaryotic genomes has progressed upward in complexity may find the following abstract from PNAS1 startling: We use the pattern of intron conservation in 684 groups of orthologs from seven fully sequenced eukaryotic genomes to provide maximum likelihood estimates of the number of introns present in the same orthologs in various […]

Ribosome Unties the Messenger-RNA Gordian Knot

Cells needing to translate their DNA into proteins have a problem.  The messenger RNAs, the molecules that carry the genetic code from the nucleus to the translating machine called the ribosome, get tied up in knots.  How does the ribosome untie them before they can begin translating?  Takyar et al., writing in Cell,1 explored this […]

Simple Darwinian Theories Have to Be Abandoned

Mutate one gene and a cascade of changes can result.  This effect is called pleiotropy (see 10/01/2003 entry).  According to an article by Stephen Strauss reporting for the Canadian newspaper Globe and Mail, “The emerging richness of pleiotropy means that any simple Darwinian notion of what is going on during natural selection has to be […]

DNA Translators Cannot Tolerate Editor Layoffs

We’ve explained elsewhere about the family of molecular machines called aminoacyl-tRNA synthetases (see 05/26/2004 entry and its embedded links).  Their job is to associate each word of DNA code (codon) with its corresponding piece of a protein (amino acid).  In a very real sense, they translate the DNA code into the protein code.  One amazing […]

DNA Coding Multiplies in Complexity

As if the discovery that DNA is a language translation system was not enough to challenge evolutionary theories, it is becoming increasing clear that DNA is a code operated by another code.  Science on Oct. 221 had a feature on gene regulation, which writer Elizabeth Pennisi termed “Genome’s Second Code.”  She began, “The genome has […]

Stupid Evolution Quote of the Week

This week’s entry has a little jargon in it, but if you remember what we’ve said about the tRNA synthetase family of proteins (see 05/26/2004, 07/21/2003 and 06/09/2003 headlines), you’ll get it.  Paul Schimmel and Karla Ewalt comment in Cell1 on new discoveries by Sampath et al.2 that two of these synthetases fuse together to […]

Genome of Diatom Reveals Unanticipated Complexity

“Let’s play 20 questions.”: “OK, I’m game.  Animal, vegetable or mineral?” “Yes.” “I give up.” The answer is: a diatom.  Some of the most abundant one-celled organisms in the sea, and essential for regulating the global carbon cycle, diatoms seem to be part animal, vegetable and mineral.  Scientists aren’t sure how to classify them.  They […]

Arrow Worms Miss the Mark in Darwin’s Tree

Nature this week1 claims that “The origins of the arrow worms have long been obscure, but molecular studies are finally bringing the true evolutionary position of these beautiful marine predators into sharper focus.” (Emphasis added in all quotes.)  Arrow worms, or Chaetognatha, are “strikingly beautiful marine animals.” writes Maximilian J. Telford.  “Their transparent, slender bodies […]

Discovery of Transfer RNA Recounted

In the Sept. 16 issue of Nature,1 Mahlon Hoagland recounts how he did the key experiment in 1957 that proved DNA used “soluble RNA” intermediates, later named transfer RNA (tRNA), on the way to protein synthesis in the ribosome, only to find that Francis Crick had predicted the existence of such intermediates. By this time […]

Salamander Genes Give Darwinists a Wake-Up Call

A press release from UC Berkeley says that the evolutionary family tree of salamanders, once thought secure, has been turned topsy-turvy by a study of the genes.  The opening paragraph is reminiscent of an irritating alarm clock going off in a comfy bedroom: Biologists take for granted that the limbs and branches of the tree […]
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