ture; Calbiochem), amide-adenine 4 ml of nicotin- dinucleotide solution (10 mg/ml), 4 ml of phenazine methosulfate solution (0.2 mg/ml), and 20 mg of nitro blue tetrazolium. Gels incubated in this mixture for about 1 hour at 20°C begin to show purple formazan in areas of GDH activity. One fly has sufficient enzyme activity to give dark areas. To insure that minor components were detected, the gels were incubated overnight in this mixture. It was found that inbred strains of D. melanogaster may be divided into two types according to the did not observe this heterogeneity in her experiment; however, Hubby and Lewontin (8) observed two areas of GDH activity in all strains of D. pseudoobscura, Crosses between the two different types yield hybrids which have five visible components with GDH activity. There are three major components: the two parental ones and a hybrid with intermediate mobility (Fig. 1). The only minor components that are detectable duced by Gdh*/Gdh* heterozygotes. The -approximate cytological position of the Gdh locus is known from analysis of Df(2L)GdhA. This second chromosome deficiency was selected from x-irradiated chromosomes which lacked the wild-type allele of cl (clot eye color). In one case the irradiation induced a deficiency which included both ci+ and Gdh. The electrophoretic pattern of Df(2L)GdhA/Gdh® is like that of Gdh® homozygetes, and Df(2L) GdhA/ GdhFis like Gdh® homozygotes. are those of the slow-type parent. In salivary gland chromosomes there Other minor components in the hybrid are a few bands missing. On Bridges’ are obscured by the three major com(11) salivary chromosome maptheleft ponents. The presence of a hybrid break of Df(2L)GdhA is between 25El major component indicates that the and 25F1. The right break is between GDH molecule contains at least two 26B1 and 26C1. The locus of Gdh protein subunits. The parental major must therefore be between 25E1 and components contain two subunits that 26C1. are alike; the hybrid contains two unE. H. GRELL like subunits (J0), Flies trapped from Biology Division, nessee, are polytypic. The rapid, slow, Oak Ridge, Tennessee 37830 a wild population in Oak Ridge, Ten- and hybrid patterns of GDH are all found in this one population. . Genetic analysis shows that the differences in electrophoretic mobility of GDH are based on there being two alleles of a genetic locus. This locus (called Glycerophosphate dehydrogenase, symbol Gdh) is located on the second chromosome. On the standard linkage map of D. melanogaster (11) it has a genetic map position of about 17.8. It is between the loci of clot eye color (map position 16.5) and Sternopleural bristles (map position 22.0). Homozygotes of the allele Gdh*® have the rapid pattern. Homozygotes of the allele Gdh® have the slow pattern of GDH. The hybrid pattern is pro- Oak Ridge National Laboratory, References and Notes 1. B. Sactor and D. G. Cochran, Biochim. Biophys. Acta 25, 649 (1957). 2. E. Zebe and W. H. McShan, J. Gen. Physiol. 40, 779 (1957). 3. B. Sactor, in The Physiology of Insecta, M. Rockstein, Ed. (Academic Press, New York, ed, 2, 1965), 483. W. Chefurka, in ibid., p. 581. . C. R. Shaw, Science 149, 936 (1965). . M. Sims, Nature 207, 757 (1965). . J. L. Hubby and L. H. Throckmorton, Geneties 52, 203 (1965). J. L. Hubby and R. C. Lewontin, ibid. 54, 577 (1966). . 5. Raymond and Y.-J. Wang, Anal. Blochem. 1, 391 (1960). 10, D. Schwartz, Proc. Nat. Acad. Sci. U.S. 52, 222 (1964). 11. C. B. Bridges and K, §. Brehme, The Mutants of Drosophila melanogaster (Carnegie Inst. Wash., publ. No, 552, 1944). 12. Research sponsored by the AEC under contract with the Union Carbide Corporation. 20 September 1967 a electro- phoretic mobility of their GDH. When the procedures described above are used, it is found that one type contains GDH that migrates more rapidly to the anode than the other. CantonS, Samarkand, and Oregon-RC are examples of common wild-type strains that contain the more rapidly migrat- ing enzyme. Swedish-c and Oregon-R have the slower migrating enzyme (see Fig. 1). There appears to be a family of enzymes in each inbred. There is a Major component and two slower-moving minor components. The whole pattern is displaced when the slower and faster types are compared. Larvae, pupae, and adults have the same patterns. Whether these multiple forms are present in the living animal or are 1320 time. Sims (6) SNA tris buffer (0.05M, pH 8.5), 0.18 g of disodium dihydrogen ethylenediaminetetraacetate, 0.8 g of disodium glycerophosphate pentahydrate (a and 8 mix- artifacts cannot be determined at this oO within species. Hubby and Lewontin (8) surveyed manystrains of D. pseudoobscura and found no electrophoretic variants of GDH, although variants of some other enzymes were common. For this investigation, Sim’s (6) technique was used with modifications to accommodate flat-bed electrophoresis equipment (EC Apparatus Corp.). Strips of polyacrylamide gel (5 percent acrylamide) were cast according to the method of Raymond and Wang (9). Before use, the gels were equilibrated with buffer of 0.025M tris brought down to pH 6.0 with H,PO,. Buffer in electrode vessels was 0.05M trisphosphate, pH 6.0. Flies were squashed on small squares of filter paper and inserted between cut ends of the gel. The top and bottom of the apparatus were cooled with running tap water. A potential of 24 volt/cm and a current of about 45 ma was applied across the gel for 2 to 4 hours. The mixture to give color to regions of GDH activity contained 90 ml of Detergent-Solubilized RNA Polymerase from Cells Infected with Foot-and-Mouth Disease Virus Abstract. The foot-and-mouth disease virus RNA polymerase complex was dissociated from cellular membranes with deoxycholate in the presence of dextran sulfate. The soluble polymerase complex was active in the cell-free synthesis of virus-specific RNA; solubilization of the complex permitted direct analysis of the cell-free reaction mixtures without recourse to RNA extraction. A major RN4A-containing component found early during cell-free incubation ranged from approximately 140 to 3008. The final major products of the cell-free system were 37S virus RNA, 208 ribonuclease-resistant RNA, and a 50S component containing RNA. Detailed studies of replication of antmal virus RNA in ceil-free systems have been hindered by high levels of nuclease or membrane-bound polym- erase complexes, or of both (/, 2). The RNA polymerase induced by the foot-and-mouth disease virus (FMDV) is reportedly bound to cellular memSCIENCE, VOL. 158