No abstract

The nucleotide sequence has been determined of a 2,500 base pair segment of the E. coli chromosome located between 3.75 and 6.25 kb counterclockwise of the origin of replication at 83.5 min. The sequence contains the atp genes coding for subunits a-, b-, c-, delta- and part of the alpha-subunit of the membrane bound ATP synthase. The precise start positions of the atpE (c), atpF (b), atpH (delta) and atpA (alpha) genes have been defined by comparison of the potential coding sequences with the known amino acid sequence of the c-subunit and the determined N-terminal amino acid sequences of the respective subunits. The genes are expressed in the counterclockwise direction. Their order (counterclockwise) is: atpB (a), atpE (c), atpF (b), atpH (delta) and atpA(alpha). The coding sequences for subunits b and delta yield polypeptides of 156 and 177 amino acids, respectively, in accordance with the established sizes of these subunits; the one for the c-subunit, the DCCD binding protein, fits perfectly with its known sequence of 79 amino acids. The a-subunit is comprised within a coding sequence yielding a polypeptide of 271 amino acids. It is suggested, however, that the a-subunit (atpB) contains only 201 amino acids, in accordance with its known size, starting from a translation initiation site within the larger coding sequence. The stoichiometry of the F0 sector subunits is discussed and a model is proposed for the functioning of the highly charged b-subunit of the F0 sector as the actual proton conductor.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This content downloaded from 142.58.129.109 on Fri, 01 Jan 2016 01:30:03 UTC All use subject to JSTOR Terms and Conditions COPEIA, 1986, NO. 1 COPEIA, 1986, NO. 1 bat. A multi-disciplinary approach to animal behavior requires close collaboration with a variety of specialists and a feature of Ryan's work is the significant input made by such people as Stanley Rand, Merlin Tuttle and GeorgeBartholomew to specific aspects of the study. This book should be required reading for any aspiring student setting out on a major study in behavioral ecology. It presents an ideal model of a careful, well thought-out research strategy, with a good blend of observational work and field experiment, securely founded in a thorough understanding of relevant theory. The only danger, so high a standard has Mike Ryan set, is that some students may be deterred by the enormity of the task from ever setting out to try to emulate him.-TIM HALLIDAY, Department

Large displacement flows in granular solids occur whenever silos are discharged. Measurements of pressures during flow, combined with visual observations of flow patterns and control tests on the ensiled solids, have revealed several phenomena contributing to pressure variations during flow. Not only are the pressure variations time dependent within a single silo, but significant systematic differences are found between one silo and another, even when the two are superficially identical and contain similar ensiled materials. One serious outcome is that silo pressures are quite unsymmetrical even in symmetrical silos, and this is a most dangerous phenomenon for the safety of the silo structure.The loss of symmetry can largely be traced to inhomogeneity and anisotropy in the ensiled material, developed by the initial packing during filling. Thus, unless the mechanism of packing is understood, the mechanics of these solids cannot be modelled. The sensitivity of granular materials to stress history and the role of geometrically imperfect boundaries present other complications in interpreting observations and understanding the mechanics of silo pressures and flow regimes.No current theory of silo loads covers these phenomena, which themselves are only illustrative examples of current shortcomings. More comprehensive constitutive models are needed for application to silos and large-scale granular solids flows.

The genes for the eight subunits of the membrane bound ATP synthase of Escherichia coli (Ca++, Mg++ dependent ATPase, EC 3.6.1.3) were mapped through genetic, physical and functional analysis of specialized transducing phages lambda asn (von Meyenburg et al. 1978). The ATP synthase genes, designated atp1, are located at 83.2 min in a segment of the chromosome between 3.5 and 11.3 kb left (counterclockwise) of the origin of replication oriC. The counterclockwise order of the genes for the eight subunits, the expression of which starts from a control region at 3.5 kb-L, was found to be: a, (c, b, delta), alpha, gamma, (epsilon, beta) which in the notation of Downie el al. (1981) reads atp B (EFH) A G (C D). The analysis was in part based on the isolation of new types of atp (unc, Suc-) mutations. We made use of the fact that specialized transducing phages lambda asn carrying oriC can establish themselves as minichromosomes rendering asnA cells Asn+, and that the resulting Asn+ cells grow slowly if the lambda asn carries part or all of the atp operon. Selecting for fast growing strains mutations were isolated on the lambda asn which either eliminated atp genes or affected their expression ("promoter" mutations). The relationship between these atp mutations and the cop mutations of Ogura et al. (1980), which also appear to map in front of or within the atp genes, is discussed.