n e w s of t h e
week Research International is considering commercialization of NRL's flow immunosensor technology. "There is a need for sensors to do [explosives] monitoring very cheaply," says David A. McCrae, Research International's vice president and chemistry director. "We think we can get to the point where we have a technology package—NRL's chemistry and our hardware—that will be a sellable item." Maureen Rouhi
Antifreeze glycoproteins look alike, evolved independently Ligler: sensor outperforms EPA method
Evidence of a rare example of convergent evolution at the molecular level which buffer continuously flows. Samples comes from scientists at the University of are injected into the flowing stream. Illinois, Urbana-Champaign, who show When no explosive is present, the fluores- that genes that encode almost identical cent analogs remain bound to the antibod- antifreeze glycoproteins in two unrelated ies. Any explosive in the sample, however, fish have different ancestral genes. displaces the fluorescent analog, which Graduate student Iiangbiao Chen, prothen is measured by a fluorescence detec- fessor of physiology Arthur L. DeVries, tor downstream. and senior research scientist Chi-Hing C. Ligler and coworkers have tested the Cheng demonstrate, in two related pabiosensor at military facilities in Oregon pers, that the antifreeze glycoprotein and Washington. Some of the sites are so (AFGP) gene in Antarctic notothenioid fish heavily contaminated "you can actually evolved from a gene that encodes trypsee explosives that have recrystallized— sinogen, a digestive enzyme. The AFGP pink rocks that are basically TNT," she gene in Arctic cod, however, shares no sesays. "You wanted to make sure you quence identity with the trypsinogen gene were wearing sneakers if you were walk- [Proa Natl Acad. Sci USA, 94, 3811 and ing around." 3817(1997)]. Analysis of groundwater samples durIn the late 1960s, DeVries discovered ing the field tests validated the biosen- that Antarctic fish are protected from sor's performance, says Ligler. Results subzero temperatures by AFGPs in their correlated highly with those from the blood serum. These glycoproteins typiEPA-approved laboratory method: "Our cally consist of repeating alanine-alanineflow sensor actually had better reproduc- threonine tripeptide units with disacchaibility than the EPA method." She adds ride groups extending from the threothat the device also compared well with nines (C&EN, March 3, page 36). The other methods being field-tested, such as threonines in Arctic cod AFGPs are ocimmunoassay kits. casionally substituted by arginine. OthThe team has looked at soil samples erwise, there is no difference between as well. Soil is shaken in acetone, the AFGPs in the two fish. mixture is filtered, and a small amount of AFGPs from the two fish are not identhe filtrate is diluted and injected directly tical twins, but rather look-alikes from into the device. Ligler says soil data from two different parents, Cheng tells C&EN. the biosensor also correlate well with "The evidence strongly points to a rare data from the EPA-approved method. and elegant case of protein sequence ligler and coworkers have been col- convergence from two different genomic laborating with Research International, a loci," she says. The work is significant, says Joseph contract R&D company based in Woodinville, Wash., to develop a portable ver- T. Eastman, professor of anatomy at sion of the biosensor. NRL received the Ohio University, Athens, because it anfirst prototype last month and will be swers three important questions in molecular evolution. "It tells us which moltesting it in the field this summer. 10 APRIL 21, 1997 C&EN
ecule was the progenitor of the antifreeze in the Antarctic fish. That was completely unknown before. It also provides an estimate of the time of appearance of antifreeze based on sequence divergence from trypsinogen, the ancestral molecule. Andfinally,it is a clear demonstration of molecular convergence," he says. Postdoctoral fellow John M. Logdson Jr. and biochemistry professor W. Ford Doolittle at Dalhousie University, Halifax, Nova Scotia, suggest in a commentary in the same issue of PNAS that the work likely will be cited as a textbook example of molecular evolution in the years to come. "Demonstrations of this sort at the molecular level are rare and noteworthy," they write. The Antarctic notothenioid and the Arctic cod belong to two different orders of fish that diverged some 40 million years ago, long before the polar oceans froze. The Illinois team demonstrates that the nucleotide sequence in the notothenioid gene that encodes trypsinogen differs by only 4 to 7% from the fish's AFGP gene. This indicates that the trypsinogen gene transformed into a new ice-binding protein gene as recently
DeVries (left) and technician Richard Wiiiis display an Antarctic notothenioid.
as 5 million to 14 million years ago. The time frame correlates well with the freez ing of the Antarctic Ocean, estimated to have occurred 10 million to 14 million years ago. "The work not only sheds light on the paleoclimate of the Antarctic Ocean, but also directly links the evolution of a new protein to the environmental driving force," says Cheng. The researchers show that the anti freeze gene in the notothenioids evolved
by the recruitment and repeated duplica tion of a nine-nucleotide segment of cod ing and noncoding DNA in the trypsinogen gene. The conversion to the AFGP gene in the Antarctic fish "is the first clear example of how an old protein gene spawned a new gene for an entire ly new protein with a new function," state the researchers. The origin of the Arctic cod AFGP gene has yet to be determined, says DeVries, "but it's certainly not tripsino
gen because the gene structures and cod ing sequences are drastically different in the two genes." Logsdon and Doolittle consider that the source of this gene and the evolu tionary events that led to its birth should be within easy reach. "It will be quite in teresting to compare the molecular mechanisms that have resulted in such a striking case of convergent evolution," they write. Michael Freemantle
Texas City recalls devastating blast
was carrying ammonium nitrate and couldn't be moved to safety—exploded. Flying debris struck, among other things, refinery and chemical storage tanks, ig niting fires that burned for days. At the time, little was understood about the explosive properties of ammo nium nitrate (C&EN, May 12, 1947, page 1334), even though shortly after World War I a warehouse full of the chemical
Sterling Chemicals. The company, which still operates the plant, held a private cere mony there last week. Other chemical companies in the city—which include Amoco, International Specialty Products, and Union Carbide—also participated in the three days of ceremonies and celebra tions, emphasizing safety, the environ ment, and community involvement. Ann Thayer
Texas City, Texas, officials and chemical companies commemorated the 50th anni versary last week of the worst industrial accident in U.S. history—fires and explo sions that killed nearly 600 people and left more than 3,000 injured.
Sites scarred by fire and devastation are now home to thriving chemical complexes.
City officials used the milestone to celebrate the area's continuing evolution as a major petrochemical manufacturing and shipping site, and as a residential community. The disaster on Galveston Bay took place on the morning of April 16, 1947, when a French freighter, the Grandcamp— carrying cotton, peanuts, and oil-well ma chinery, and in the process of loading about 2,500 tons of ammonium nitrate fertil izer—caught fire. About an hour later, the ship exploded. Many of those who died in the town of 16,000 had come down to the waterfront to watch the firefighting. The 1947 blast devastated a Monsanto styrene plant adjacent to the docks, kill ing about 230 workers. A tidal wave washed 150 feet inland.. That night, a nearby ship, the High Flyer—which also
exploded at a BASF plant and killed sev eral thousand people in Ludwigshafen, Germany. Ammonium nitrate fertilizers mixed with fuel oil are now common in dustrial explosives as well as a tool of choice by terrorist bombers. Robert G. Potter, who heads Monsanto's chemical operations, in a letter to Texas City's mayor called the disaster "unequaled before or since in Monsanto's history." Calling the event both trag ic and heroic, he said Monsanto's histori cal records "describe a community, even though stunned and reeling, which ral lied around its people." Monsanto decided to rebuild the plant that had been constructed in 1943 to help supply the government's synthetic rubber needs during World War Π. In 1986, Gor don Cain bought the plant and created
From the ACS meeting
New membership campaign kicked off in San Francisco Registration for last week's American Chemical Society national meeting in San Francisco came agonizingly close to a record: At 14,846 people registered as of April 16, the figure was just 201 people shy of the 15,047 registered for the fall 1957 national meeting in New York City. Nonetheless, the meeting boasted some firsts. ACS President Paul S. Ander son points out that a record 7,745 techni cal papers were submitted for presentaAPRIL 21, 1997 C&EN 11
