spectrometer. This year the amount was about $70,000—"some general grants, a couple of specific programs, and a little bit of equipment." Central Michigan has requested a meeting, Dow says, and the issue "likely will be resolved very soon." The school con firms that negotiations are under way. So far, however, it hasn't accepted Oreffice's offer to speak. D
PPG to close chlorine, caustic, soda ash units An era is passing away for P P G In dustries as the company leaves the soda ash business, which brought it originally into chemicals in 1899. Last week, PPG said it plans to shut down soda ash, chlorine, and caustic soda production at Corpus Christi, Tex., by March 31,1978. The company still will produce chrome chemicals at this site and may expand this capacity. It was a soda ash plant at Barberton, Ohio, started up at the close of the 19th century as Columbia Chemical Co. and closed down in 1973, that began PPG's involvement in chemicals. The plant supplied material for glass operations owned by the same outfit and called Pitts burgh Plate Glass. PPG started up the Corpus Christi soda ash plant in 1931 as a pioneer alkali operation on the Gulf Coast. Until 1951, the plant was a joint venture with American Cyanamid. The pioneering plant of the 1930's has now become an economic dropout because of disadvantages in technol ogy and operating costs. The Corpus Christi soda ash plant, with capacity of 800 tons per day, is one of the three remaining Solvay-process plants in the U.S. (the other two being BASF Wyandotte's south of Detroit and Allied Chemical's in Syracuse). These plants have suffered greatly compet ing with the big natural soda ash de velopment in Wyoming. Unlike Al lied, P P G decided not to invest in natural soda ash. The chlorine-caustic unit at Corpus Christi has capacity of 250 tons per day of chlorine and a bit more of caustic soda. PPG is effectively re placing this capacity with a 750 tonper-day addition coming on stream shortly at Lake Charles, La. The closing at Corpus Christi will reduce PPG's employment at the site from 660 to 270. The company says that some technical employees will be involved but few of the 70 profes sionals at the technical center will be affected. Retirements and transfers will be used wherever possible. PPG plans a job assistance program to re locate employees being let go. D 6
C&ENNov. 7, 1977
Silent DNA found within iimal gene When the genetic code was cracked, some scientists thought it was simple because it was linear. The code has stayed linear, but that hasn't kept it from proving to be complicated in unexpected ways. National Institutes of Health scientists, led by Dr. Philip A. Leder, have found that certain DNA contains an intervening se quence of nucleotide bases that isn't subsequently expressed in either the RNA or the protein made from it. "Nature may have chosen to build this complex [animal] genome as a mechanism for creating a variety of genes from linear sequences," Leder told an overflow audience at NIH in Bethesda, Md., last week. Hemoglobin, the protein t h a t carries oxygen in blood, contains two pairs of chains, called alpha and beta. Leder and colleagues recently cloned mouse β-globin genes. Much to their surprise, they found that β-globin DNA carries a large stretch of "silent" DNA couched within it. This "inter vening sequence" runs for about 550 nucleotide bases and interrupts the /3-globin between the sites that code for amino acids 104 and 105. Another, but smaller, intervening sequence
probably exists in the β-globin gene, "so β-globin probably is divided into three discrete sequences." The intervening sequence appears neither in the β-globin protein nor in its messenger RNA (the intermediate made from the DNA and used by the cell to make the protein). Leder speculates that the cell employs "a bight and splice mechanism" to re move such intervening sequences before they're turned into protein. Though their purpose is not known, Leder speculates that such intervening sequences offer great potential for variations within genes. For example, immunoglobulins might come from just such a variable mechanism within the genes. Immu noglobulins are the million or so proteins that the body uses as part of its defense against foreign substances. Each immunoglobulin contains a constant and a variable region of amino acids. Leder has preliminary evidence that these two regions are separated by an intervening DNA sequence. That sequence might be involved in designating the shift from one type of immunoglobulin to an other. D
Methagens called new fo m of life The microorganisms that produce methane by oxidizing hydrogen and reducing carbon dioxide may not be bacteria at all, but a distinct form of life that began a separate evolution more than 3.4 billion years ago. Such are the conclusions of a team of geneticists and microbiologists at the University of Illinois, Urbana, headed by Dr. Carl R. Woese and Dr. George E. Fox. These scientists examined the nu cleic acid sequence of a ribosomal subunit in 10 different strains of these organisms—which they call metha gens. Because the subunit plays a key role in synthesizing proteins neces sary to the organism, its nucleic acid sequence is thought to have been "locked in" early in the organism's evolution. The scientists find that the se quence in methagens is very different from that found in either bacteria or in higher forms of life. In addition, methagens have a different cell wall chemistry and a unique enzyme sys tem. These differences make them a separate life form. Evolutionary geneticists consider the number of differences in the nu cleic acid sequence of a fundamental cell component like the ribosome to be an indicator of how long ago two
species branched off from each other in their evolutionary development. By this measure, the methagens sep arated from bacteria at least as early as did the blue-green algae, the sci entists say, probably more than 3.4 billion years ago. "This ties in beautifully with the concept of chemical evolution," says Dr. Cyril Ponnamperuma, a specialist in chemical evolution at the Univer sity of Maryland. Before 2 billion years ago, the earth's atmosphere would have contained essentially no oxygen and larger amounts of hy drogen and carbon dioxide than now, according to chemical evolutionists —precisely the environment that methagens flourish in. Another indicator that the metha gens developed very early in evolution is that their base pairing is different from that in bacteria. Their transfer RNA lacks a common sequence found in all other previously characterized major groups of organisms. "Now we see there were some things [that evolved] before the universal genetic code was firmly established," Pon namperuma explains. He thinks this finding is also consistent with the changing chemical environment of the earth during the early evolution of life. D
