Archive for March, 2005

Photoaffinity labeling analysis of the interaction of pituitary adenylate-cyclase-activating polypeptide (PACAP) with the PACAP type I receptor

March 28, 2005

Photoaffinity labeling analysis of the interaction of pituitary adenylate-cyclase-activating polypeptide (PACAP) with the PACAP type I receptor — Cao et al. 244 (2): 400 — FEBS Journal: “YJ Cao, E Kojro, G Gimpl, M Jasionowski, F Kasprzykowski, L Lankiewicz and F Fahrenholz

Max-Planck-Institut fur Biophysik, Frankfurt am Main, Germany.

To identify residues and domains of the peptide hormone pituitary adenylate-cyclase-activating polypeptide (PACAP) that interact with the type I receptor, two photoreactive analogues of PACAP-(1-27)-peptide were synthesized using solid-phase peptide synthesis. Phe6 or Tyr22 within the PACAP sequence were replaced by p-benzoyl-L-phenylalanine (Bz-Phe) thus creating two PACAP derivatives with a photoreactive amino acid in either the disordered N-terminal or the helical C-terminal part of the peptide. The ligand-binding properties and the efficiencies of these peptide analogues as photolabels were tested for pig brain PACAP receptors. [Bz-Phe6]-PACAP-(1-27)-peptide (Kd 1.3 nM) retained the high binding affinity of PACAP-(1-27)-peptide (Kd 0.5 nM), wheras Bz-Phe substitution of Tyr22 reduced the affinity about tenfold (Kd 4.4 nM) thus demonstrating the importance of Tyr22 for receptor binding. Monoiodination of the photoreactive analogues did not change the binding affinity of the photoreactive analogues. Photoaffinity labeling using pig brain membrane demonstrated that the 125I-labeled photoreactive analogues specifically label a 66000-Mr protein band. Photoaffinity labeling of the rat brain PACAP receptor expressed in COS cells resulted in two specifically photolabeled proteins: a major band of Mr 58000 and a minor band of Mr 78000. By treatment of photolabeled membranes with N-glycosidase F, both of the polypeptide bands were converted to a single polypeptide band of Mr 54000, which corresponds to the deglycosylated PACAP receptor. Despite its lower receptor affinity, [Bz-Phe22]-PACAP-(1-27)-peptide labeled the PACAP type I receptor in pig brain membranes and the rat receptor expressed in COS cells with much higher efficiency (20-fold for the pig receptor) than [Bz-Phe6]-PACAP-(1-27)-peptide. These findings suggest that Tyr22 in PACAP-(1-27)-peptide is located in or close to the hormone-binding site of the PACAP type I receptor. The results provide evidence that the alpha-helical C-terminal region of PACAP is directly involved in receptor binding.”

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I need to look into photoaffinity labeling more. Combine that with engineered protien crystallization, and hmmm….

Soft Tissues From T. rex Fossil

March 25, 2005

AAAS – AAAS News Release: “A recently discovered Tyrannosaurus rex fossil appears to contain elastic soft tissues, blood vessels and cells, researchers report in the 25 March 2005 issue of the journal Science.

Tissues other than bone can be preserved in the fossil record, but it’s usually difficult to determine their original form and composition in fossils more than a few million years old. These findings show that soft tissues can be clearly preserved for much longer, since this T. rex specimen, known as MOR 1125, is roughly 70 million years old.

Mary Higby Schweitzer and colleagues noticed unusual tissue fragments lining the marrow cavity of the MOR 1125 femur. When they dissolved the mineral deposits in the tissues, the authors were left with a flexible, stretchy material threaded with what looked like blood vessels. The treatment also released some thin, transparent soft tissue vessels that floated freely in the solution. These vessels resemble vessels from modern-day ostrich bone, the authors report.

Both the dinosaur and ostrich vessels also contained small, reddish brown dots that might be nuclei of the ‘endothelial’ cells that line blood vessels. Certain portions of the T. rex bone also contained fibril-like structures that looked virtually identical to bone cells called ‘osteocytes’ seen among collagen fibers in the ostrich bone.

The exquisite preservation of this tissue, which does not challenge the timing of dinosaur evolution, may open up avenues for studying dinosaur physiology and perhaps some aspects of their biochemistry, especially if researchers can identify soft tissues in other fossils as well.”

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That is pretty wild. Imagine this plot, scientist clone dinosaurs, grow them on a tropical island, and then they run amok, causing a blockbuster trilogy of movies. Oh wait, someone did that already.

Yahoo! News – Senate Votes to Open Alaskan Oil Drilling

March 16, 2005

Yahoo! News – Senate Votes to Open Alaskan Oil Drilling: “By H. JOSEF HEBERT, Associated Press Writer

WASHINGTON – Amid the backdrop of soaring oil and gasoline prices, a sharply divided Senate on Wednesday voted to open the ecologically rich Alaska wildlife refuge to oil drilling, delivering a major energy policy win for President Bush.”

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Great. If we want to get off of foreign oil, why aren’t we increasing fuel efficiency? Oh right, we’re short sighted and profit driven. The easy, Republican-friendly plot is enviro terrorists doing something to stop it but the FBI prevents it. Better is for the bad guys to be foreign oil agents, or perhaps they are in cahoots, or even one group is playing the other.

Even better is to have it happen and then show the long term economic and environmental impact. The setting of a near future novel could be scientists trying to recover from the damage, or a world where Korea took over as the dominant source for vehicles since we failed to pursue the new technology.

Yahoo! News – Large Plume Billows From Mount St. Helens

March 8, 2005

Yahoo! News – Large Plume Billows From Mount St. Helens: “MOUNT ST. HELENS, Wash. – Mount St. Helens released a towering plume of ash Tuesday, its most significant emission in months but one that seismologists did not believe heralded any major eruption.”

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Remember that movie Dante’s Peak with Pierce Brosnan and that serious off road Suburban? Great thriller that didn’t get much recognition.

Yahoo! News – Few Clues on Dolphin Deaths in Florida Keys

March 8, 2005

Yahoo! News – Few Clues on Dolphin Deaths in Florida Keys: “By Laura Myers

SUMMERLAND KEY, Fla. (Reuters) – Biologists are investigating whether sonar used in U.S. Navy (news – web sites) submarine exercises or red tide bacteria contributed to the deaths of more than 30 rough-toothed dolphins in a mass stranding in the Florida Keys last week.”

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Sad and weird. It sounds like the opening of a thriller. Hopefully they will figure it out, though I didn’t think you could get decompression sickness unless you breathe compressed air at depth. Skin diving, which the dolphins do, can’t result in it. Unless I missed something.

Yahoo! News – Tiny Early ‘Hobbit’ Human Was Smart, Skull Shows

March 3, 2005

Yahoo! News – Tiny Early ‘Hobbit’ Human Was Smart, Skull Shows: “By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) – Tiny pre-humans who lived on an Indonesian island until about 12,000 years ago had brains so surprisingly sophisticated that the creatures may represent a previously unrecognized species of early humans, or hominids, scientists reported on Thursday.”

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OK, no plot here, but I have to put a news article about real hobbits on the blog. I think it was in the small print somewhere (ha ha).