News of the Week
Rat growth hormone gene works in mice Efforts to transfer between two species working genes that are maintained under well-defined control have moved forward another step. A group of scientists from four research centers in the U.S. have moved the gene for growth hormone from rats into mice where it's active but also under the partial control of a mouse genetic element, known as a gene promoter. This research, published in the British weekly, Nature, was led by Richard Palmiter from the University of Washington, Seattle; Ralph Brinster of the University of Pennsylvania, Philadelphia; Michael G. Rosenfeld from the University of California, San Diego; and Ronald M. Evans from the Salk Institute for Biological Studies, also of San Diego, and the effort was joined by colleagues from those institutions. The transfer technology extends techniques pioneered by Brinster and Palmiter (C&EN, Oct. 11, page 28) in which refined microinjection procedures are used to place modified genetic materials into fertilized mouse eggs, which are carried to term in "foster" mothers. This procedure allows the researchers temporarily to remove DNA from cells, change it chemically and biochemically, and then put it back into mice to see whether those manipulations are successful in a biological sense. The DNA from rats, coding for growth hormone, will not work by itself in mice. Thus, in the current research, t h a t gene was attached biochemically to part of a mouse gene, namely the control region of the metallothionein gene. This gene, which ordinarily is responsive to certain hormones and heavy metals and is involved in the metabolism of those metals, was used as a means of controlling the foreign rat gene. The mouse control gene element works for the rat growth hormone gene, judging from the accelerated growth of some of the recipient mice to about twice their normal size, the researchers say. "This was confirmed by chemical analyses of their [the mice] blood, which showed that the rapidly growing mice contained unusually large amounts of growth hormone," the researchers add. The hormone is produced mainly in the livers of the animals, the organ where the metallothionein gene ordinarily is active. Growth hormone ordinarily is made by the pituitary gland. 8
C&EN Dec. 20, 1982
Not all of the genetic control problems are solved, however. It's still uncertain whether the growth-hormone-linked metallothionein element responds to metals, as it ordinarily can. When recipient mice were fed zinc to see whether the metallothionein element responded, results were ambiguous, and mice grew rapidly even without the supplement, the researchers report. Moreover, the number of copies of the transferred gene and their location on the mouse chromosomes varied among the recipient mice, pointing out that the injection procedure still is fairly unspecific. One other perplexing problem is t h a t many of the recipient mice are sterile, which suggests that other genes may be affected by the procedures. And, finally, it's not known what other organs may be affected or how many copies of the transferred genes are working in the recipient animals. D
Carbide restarting Taft plant following fire An explosion and fire Dec. 11 in a tank farm at Union Carbide's Taft, La., complex caused all production units to be shut down. At the middle of last week, Carbide officials expected to restart most units by the end of the week. No one was hurt in the accident. At press time, the cause of the explosion had not been determined. Apparently, the explosion occurred
in a tank containing acrolein, a poisonous and highly reactive liquid with a choking odor. (Carbide uses the chemical as an intermediate in making various products such as an algaecide and animal feed supplements.) Other tanks containing acrolein also burned. The explosion and fire damaged to varying degrees some other tanks nearby. Because of the fire, local government officials in the area about 20 miles west of New Orleans ordered evacuation of residents within a fivemile radius of the Taft plant. Based on population estimates, some 17,000 people obeyed the order, according to press reports. The evacuation began at 5 AM, and was called off the following morning. Carbide officials say that no process units in the Taft plant were damaged by the accident, but all were shut down as a precaution. Loss of the tankage was not expected to interfere with any plant operation or shipping from the plant. Fires burned in the acrolein tank area for most of the day of the explosion. Firemen allowed the fires to burn to consume the acrolein to prevent loss of it into the atmosphere. Testing by the Louisiana Air Quality Control Commission indicated that no acrolein or toxic fumes were escaping from the plant site about 12 hours after the explosion. Once the fires were out, inspection teams went into the tank farm and found the remaining tanks in secure and stable condition, according to a company spokesman. G
Charred remains of tanks ( left) following explosion and fire at Carbide plant
