Contents Vol. 68, No. 3 March 1971

Phgsial Sciences ASTRONOMY Performance of an automated computezoed plate scanner ...... Willem J. Luyten 513-516 CHEMISTRY Effect of pressure on the electronic structure of ferric hydroxamates and ferrichrome A. . D. C. Grenoble and H. G. Drickamer 549-553 Photocatalytic production of organic compounds from CO and IO2 in a simulated Martian atmosphere

...... Jerry S. Hubbard, James P. Hardy, and N. H. Horowitz 574-578 MATHEMATICS Subordinate quadratic forms and their complementary forms ...... Marston Morse 579 The Weierstras&PiLaguerre transform ...... H. M. Srivastava 554-556 PHYSICS One- and two-fluid van der Waals theories of liquid mixtures, II. 6:12 molecules.

...... Douglas Henderson and Peter J. Leonard 632-635 -e APPLIED PHY5It vidence of widespread effects of cloud seeding at two Arizona experiments ......

SCIENCES...... Jerzy Neyman and Herbert B. Osborn 649-652 .iologicsal S ~eas 'WHE IIsTRY Mammalian peptide chain termination, II. Codon specificity and GTPase activity of release factor

...... Arthur L. Beaudet and C. T. Caskey 619-624 Adenyl cyclase as a link between photon capture and changes in membrane permeability of frog photo- receptors ...... Mark W. Bitensky, Ronnie E. Gorman, and William H. Miller 561-562 Light-induced electron. transfer reactions.between chlorophyll a and hydrogenated pteridine derivatives in

solution. . A. M. Bobst 541-543 On the concept of orbital steering in catalytic reactions ...... Thomas.. . C. Bruice, Allister Brown, and David 0. Harris 658-661 The question of histidine content in c-type cytochromes ...... M. A. Cusanovich, T. Meyer, S. M. Tedro, and M. D. Kamen- 629-631 The leader sequence from the 5'-termninus,,to the A-protein initiation codon in MS2-virus RNA. ....B...... R. De Wachter, A. Vandenberghe, J. Merregaert, R. Contreras, and W. Fiers 585-589 Compounds I of cata1hse and horse radish peroxidase: r-cation radicals ...... D. Dolphin, A. Forman, D. C. Borg, J. Fajer, and R. H. Felton 614-618 Heme binding and transport-a spectrophotometric study of plasma glycoglobulin hemochromogens

- ,f ...... DavidL. Drabkin 609-613 The yeast phenylalanyl transfer RNA synthetase recognition site: the region adjacent to the dihydrouri- -!.t "'., dine ...... B. C. K. and R. Reszelbach 681-684 I loop Dudock, DiPeri, Scileppi, I,- Control of translation by the conformation of messenger RNA Hiroichi Fukami and Kazuto Imahori 570-573e i. 'o The carboxyl transferase component of acetyl CoA carboxylase: Structural evidence for intersubunit trans- locationrof the biotin prosthetic group Ras B. Guchhait, Joel Moss, Walter Sokolski, and M. Daniel Lane 653-657 Optical activity of human lysozyme . . . . . J. P. Halper, N. Latovitzki, H. Bernstein, and S. Beychok 517-522 Direction of chain elongation in the formation of Escherichia coli ribosomal protein...... Sunao Iwata and Hideko, Kaji 690-694' Absence of histones from the chromosomal proteins of fungi ...... T. J. Leighton, B. C. Dill, J. J. Stock, and Cornell Phillips 677-680 Specific transformylation of one methionyl-tRNA from cotton seedling chloreplasts by endogenous and

Escherichia coli transformylases ...... William C. Merrick and L. S. Dure III 641-644 The mechanism of protein synthesis activation after fertilization of sea urchin eggs...... S. Metafora, L. Felicetti, and RB Gambino 600604 Electron spin resonance of chlorophyll and the origin of signal I in photosynthesis. s...... J. R. Norris, R. A. Uphaus, H. L. Crespi, and J. J. Katz 625-628 -r Biochemical studies on adenovirus multiplication, XIX. Resolution of late viral RNA species in the nucleus and cytoplasm .. . . . J. Thomas Parsons, Jacqueline Gardner, and Maurice Green 557-560 Substrate anchoring and the catalytic power of enzymes ...... Jacques Reuben 563-565 Putrescine and spermidine biosynthesis in the development.of normal and anucleolate mutants of Xenopus

laevis ...... Diane H. Rustell 523-527 Inhibition of the metabclism of 25-hydroxycholecalciferol by actinomycin D and cycloheximide ...... Y. Tanaka and H. F. DeLuca 605-608 The gramicidin A trafismembrane channel: a proposed T(L,D) helix ...... D. W. Urry 672-676 BOTANY Pat.hasrnicit.vV%.1 reoiflt.inf from mtitsit.inn at the, h nloeq nf rLtilannn aleiiq-- ...... : . . P. R. Day, S. L. Anagnostakis, and J. W. Puhalla 533-535 Isolation of glucanase-containing particles from budding Saccharomyces cerevisiae. P. M. A. and A. 636-640 ...... Matile, Cortat, Wjemken, Frey-Wyssling

GENETICS Cytological and biochemical correlation of late X-chromosome replication and gene inactivation in the

mule ...... Maimon M. Cohen and Mario C. Rattazzi 544-548 (Continuedon inside back cover) Contents (Continued from outside back cover)

IMMUNOLOGY Amino acid sequences of two mouse immunoglobulin lambda chains .E...... t.ttore. Appella 590-594 Expression of H-2 and Moloney leukemia virus-determined cell-surface antigens in synchronized cultures of a mouse cell line...... Matko Cilkes and Sten Friberg, Jr. 566-569 MEDICAL Effects of L-dopa on norepinephrine metabolism in the brain. SCIENCES J. P. Chalmers, R. J. Baldessarini, and R. J. Wurtman 662-666 MICROBIOLOGY Use of monkey-mouse hybrid cells for the study of the cellular regulation of interferon production and action ...... R. Cassingena, C. Chany, M. Vignal, H. Suarez, S. Estrade, and P. Lazar 580-584 Serum factor requirements of normal and simian virus 40-transformed 3T3 mouse fibroblasts...... DieterPaul, Allan Lipton, and Ingrid Klinger 645-648 PHYSIOLOGY A mechanochemical mechanism for muscle contraction ...... William F. Harrington 685-689 Kinetics of insulin release from the perfused rat pancreas caused by glucose, glucosamine, and galactose

...... Raidiger Landgraf, Janina Kotler-Brajtburg, and Franz M. Matschinsky 536-540 ZOOLOGY Chromosomal aberrations and mortality of x-irradiated mammalian cells: emphasis on repair...... W. C. Dewey, H. H. Miller, and D. B. Leeper 667-671 Absence of adaptive modification in developing retinotectal connections in frogs after visual deprivation or disparate stimulation of the eyes ...... Marcus Jacobson 528-532 Hour-glass behavior of the circadian clock controlling eclosion of the silkmoth Antheraea pernyi.

...... James...... W. Truman 595-596