taeie es4 eh Pam “ Mii akon na aa ce AnaanEe tedte = tein ot Focne Ree Electrophoretic Variants of a-Glycerophosphate Dehydrogenase in Drosophila melanogaster Abstract. Two alleles of Gdh, the locus specifying the electrophoretic mobility of a-glycerephosphate dehydrogenase, are found in Drosophila melano- gaster. The gene is located on the sec- ond chromosome at a map position of 17.8. Hybrid enzyme molecules are found in heterozygotes. The enzyme aq-glycerophosphate de- hydrogenase (GDH) catalyzes the oxi- dation of «-glycerophosphate to dihydroxyacetone phosphate and the reverse reaction. Extraordinarily high activity of this enzyme is found in thoracic muscle of insects (7, 2), where it plays an important role in the rapid production of energy from carbohydrate [see reviews by Sacktor (3) and Chef- urka (4)]. Electrophoretic variants of at least 12 enzymes are known in Drosophila melanogaster [see review by Shaw (5)]. More than one electrophoretic type of an enzyme is more the rule Fig. 2. Globigerina bulloides (d’Orbigny); Recent, Scotian Shelf at 50 m. Note narrow elongate spines over entire surface, concentration of spines in apertural region, and absence of any form of bilamellar or secondary thickening (x 400). The secondary layers can be counted by focusing on individual pores. Both bilamellar and secondary thickening support the hypothesis (3) that shell thickening occurs at depth in adult stages of planktonic Foraminifera. Spinal development in G. bulloides at depth is contrary to findings of Bé and Hamlin (4), who found spines only in juveniles living at or near the surface of the ocean. I have also investigated differences in microstructure of other foraminiferal species (5). Globoquadrina dehiscens dehiscens (Chapman, Parr, and Collins) differs radically from Globigerina in wall structure as well as in having prominent apertural flaps covering each aperture. Globigerinoides trilobus trilobus (Ruess) displays a heavy cancel- late pore pattern, characteristic of the Globigerinoides group. However, Globigerinoides trilobus immaturus LeRoy, considered by many to be a member within the G, trilobus (s.1.) evolutionary sequence, has a surface cov- ered with irregularly spaced knobs and small circular pores; this wall structure resembles that of Globigerina. I have mentioned only a few morpho8 DECEMBER 1967 logic characteristics. Many detailed features of various microorganisms, hither- to unavailable, are being investigated and will now add greatly to the determination of evolutionary sequences and specific. generic, and familial relations; they will enable more natural than the exception in this species. The genetic loci responsible for the variations have in most cases been located on the linkage map of Drosophila. A method for acrylamide gel electrophoresis of a-glycerophosphate dehydrogenase of Drosophila has been described by Sims (6). Hubby and Throckmorton (7) examined GDH electrophoretic patterns of several spe- cies of the virilis group of Drosophila and found differences between but not classification of these microorganisms. This new insight can be attributed to the scanning electron microscope. GRANT A. BARTLETT Micropaleontology, Bedford Institute of Oceanography, P.O. Box 1006, Dartmauth, Nova Scotia References and Notes 1.C. W. Oatley, Sci. Progr. Oxford 54, 483 (1966); , W. C, Nixon, R. F. W. Pease, Advan. Electron. Electron Phys. 21, 181 (19653; T. L. Hayes, R. F. W. Pease, L. W. McDonald. Lab. Invest. 15, 1320 (1966). 2, R. F. W. Pease, T. L. Hayes, A. S. Camp, N. M. Amer, Science 154, 1185 (1966). 3. A. W. H. Bé, Micrapaleontology WU, 1 (1965); and L, Lott, Science 145, 823 (1964); A. W. H. Bé, A. Mcintyre, D. L. Breger, Ecol. Geol, Helv. 89, 2 (1966). 4. A. W. H. Bé and W. H. Hamlin, Micropaleontology, 13, 1, 87 (1967). 5. G. A. Bartlett, Can. J. Earth Sei., in press. 6. I thank Charles Godden, Marine Geology Division, Bedford Institute of Gceanography, for his active interest and the photographs {taken with the aid of the Jeoleo scanning electron microscope: Jeolco (U.S.A.) Inc., 477 Riverside Drive. Medford. Mass.]. 2! August 1967 convear corvcar® —carPoar? Fig. 1. Acrylamide-gel electrophoresis of - a-glycerophosphate dehydrogenases of Drosophila melanogaster. On the left is the homozygote of the rapid type of GDH. On the right is the homozygote of the slow type of GDH. In the center are two heterozygotes of the two alleles. 1319