Characterization of the extracellular lipase of Bacillus subtilis and its relationship to a membrane-bound lipase found in a mutant strain

Bacillus subtilis CMK33 is a mutant that is more osmotically fragile than the wild type when it is converted to the protoplast form. The protoplasts of this mutant contain a membrane-bound lipase, which is not found in protoplasts of the wild type. Hydrolysis of the membrane lipid of mutant protoplasts by the lipase is the cause of their fragility. A protein found in the wild type organism specifically inhibits the lipase (Kent, C., and Lennarz, W. J. (1972) Proc. Natl. Acad. Sci. U. S. A. 69, 2793-2797). This paper reports that cultures of both mutant and wild type cells contain an extracellular lipase which accumulates during the logarithmic phase of growth. The extracellular activity appears to be induced by a component of the growth medium. The membrane-bound lipase of the mutant has been partially purified and its properties have been compared to those of the extracellular lipase of the wild type. Their properties and sensitivity to the wild type inhibitor are similar, which suggests that the two molecules are closely related. The subcellular location of the lipase in the mutant has been investigated and compared to the location of the membrane-bound portion of the lipase inhibitor in the wild type. The lipase is located almost exclusively in the cytoplasmic membrane and not in mesosomal vesicles. In contrast, the lipase inhibitor is located in both types of membranes and is more concentrated in mesosomal vesicles. Under appropriate conditions, the appearance of new extracellular lipase activity in mutant cultures is paralleled by the loss of an equivalent amount of lipase activity from protoplasts prepared from the cells. This suggests that the membrane-bound lipase may be an intermediate in the secretion of the extracellular lipase. Because of the mutation in B. subtilis CMK33, which results in the absence of the lipase inhibitor, this intermediate can be found in protoplasts of the mutant, although it is not detectable in the wild type. Consequently, the mutant may be useful in studies of the mechanism of secretion of exoenzymes by Bacilli

Barbaetis: A New Genus of Eastern Nearctic Mayflies (Ephemeroptera: Baetidae)

The new genus Barbaetis Waltz and McCafferty, and new species Barbaetis benfieldi Kennedy are described from larvae collected from the New River, Virginia. Barbaetis is easily told from Baetis by the presence of procoxal osmobranchia. Cladistics of B. benfieldi, related Pseudocloeon species, and the lutheri and pavidus complexes of Baetis are presented and indicate the need for further taxonomic revision. The habitat of B. benfieldi is described in terms of several ecological parameters. The new species demonstrates a univoltine life history with postembryonic development restricted to a short springtime period

Opening of an interface flaw in a layered elastic half-plane under compressive loading

A static analysis is given of the problem of an elastic layer perfectly bonded, except for a frictionless interface crack, to a dissimilar elastic half-plane. The free surface of the layer is loaded by a finite pressure distribution directly over the crack. The problem is formulated using the two dimensional linear elasticity equations. Using Fourier transforms, the governing equations are converted to a pair of coupled singular integral equations. The integral equations are reduced to a set of simultaneous algebraic equations by expanding the unknown functions in a series of Jacobi polynomials and then evaluating the singular Cauchy-type integrals. The resulting equations are found to be ill-conditioned and, consequently, are solved in the least-squares sense. Results from the analysis show that, under a normal pressure distribution on the free surface of the layer and depending on the combination of geometric and material parameters, the ends of the crack can open. The resulting stresses at the crack-tips are singular, implying that crack growth is possible. The extent of the opening and the crack-top stress intensity factors depend on the width of the pressure distribution zone, the layer thickness, and the relative material properties of the layer and half-plane

Letter from W. J. Kennedy

Letter of recommendation for W. T. McDonal

Frog foams and natural protein surfactants

Foams and surfactants are relatively rare in biology because of their potential to harm cell membranes and other delicate tissues. However, in recent work we have identified and characterized a number of natural surfactant proteins found in the foam nests of tropical frogs and other unusual sources. These proteins, and their associated foams, are relatively stable and bio-compatible, but with intriguing molecular structures that reveal a new class of surfactant activity. Here we review the structures and functional mechanisms of some of these proteins as revealed by experiments involving a range of biophysical and biochemical techniques, with additional mechanistic support coming from more recent site-directed mutagenesis studies

Preliminary work toward the development of a dimensional tolerance standard for rapid prototyping

Rapid prototyping is a new technology for building parts quickly from CAD models. It works by slicing a CAD model into layers, then by building a model of the part one layer at a time. Since most parts can be sliced, most parts can be modeled using rapid prototyping. The layers themselves are created in a number of different ways - by using a laser to cure a layer of an epoxy or a resin, by depositing a layer of plastic or wax upon a surface, by using a laser to sinter a layer of powder, or by using a laser to cut a layer of paper. Rapid prototyping (RP) is new, and a standard part for use in comparing dimensional tolerances has not yet been chosen and accepted by ASTM (the American Society for Testing Materials). Such a part is needed when RP is used to build parts for investment casting or for direct use. The objective of this project was to start the development of a standard part by using statistical techniques to choose the features of the part which show curl - the vertical deviation of a part from its intended horizontal plane

System configuration and executive requirements specifications for reusable shuttle and space station/base

System configuration and executive requirements specifications for reusable shuttle and space station/bas

Cenomanian ammonites from Santander (Cantabria) and Sopeira (Aragón, southcentral Pyrenees), northern Spain

Ammonites del Cenomaniense de Santander (Cantabria) y de Sopeira (Aragón, Pirineos centro-meridionales), España septentrional. Se describen por primera vez ammonites del Cenomaniense superior (Cretácico) de los alrededores de Santander y de Sopeira (provincia de Huesca), España septentrional. Las siguientes especies están presentes: Tetragonites subtimotheanus Wiedmann, 1962, Calycoceras ( Newboldiceras) asiaticum asiaticum (Jimbo, 1894), Calycoceras ( Newboldiceras) planecostatum (Kossmat, 1897), Eucalycoceras pentagonum (Jukes-Browne, 1896), Eucalycoceras jeanneti Collignon, 1937 y Thomelites sornayi (Thomel, 1966). Esta asociación es típica de la parte inferior del Cenomaniense superior de la zona de Calycoceras (Proeucalycoceras) guerangeri a excepción de E. jeanneti, conocido solamente de Madagascar.Upper Cenomanian (Cretaceous) ammonites are described for the first time from the environs of Santander (Cantabria) and Sopeira (Aragón, Huesca province) in northern Spain. The following species are present: Tetragonites subtimotheanus Wiedmann, 1962, Calycoceras( Newboldiceras) asiaticum asiaticum(Jimbo, 1894), Calycoceras( Newboldiceras) planecostatum(Kossmat, 1897), Eucalycoceras pentagonum(Jukes-Browne,1896), Eucalycoceras jeannetiCollignon, 1937, and Thomelites sornayi(Thomel, 1966). This assemblage is typical of the lower Upper Cenomanian Calycoceras ( Proeucalycoceras) guerangeriZone, with the exception of E. jeanneti, previously known only from Madagascar.Ammonites del Cenomaniense de Santander (Cantabria) y de Sopeira (Aragón, Pirineos centro-meridionales), España septentrional. Se describen por primera vez ammonites del Cenomaniense superior (Cretácico) de los alrededores de Santander y de Sopeira (provincia de Huesca), España septentrional. Las siguientes especies están presentes: Tetragonites subtimotheanus Wiedmann, 1962, Calycoceras ( Newboldiceras) asiaticum asiaticum (Jimbo, 1894), Calycoceras ( Newboldiceras) planecostatum (Kossmat, 1897), Eucalycoceras pentagonum (Jukes-Browne, 1896), Eucalycoceras jeanneti Collignon, 1937 y Thomelites sornayi (Thomel, 1966). Esta asociación es típica de la parte inferior del Cenomaniense superior de la zona de Calycoceras (Proeucalycoceras) guerangeri a excepción de E. jeanneti, conocido solamente de Madagascar

Cenomanian ammonites from the condensed deposits of the Helvetic Domain (western Alps, France and Switzerland)

The Cenomanian ammonites of the Helvetic Domain (French-Swiss Western Alps) are revised and illustrated for the first time since the middle of the Nineteenth Century. The faunas occur in remarkable condensed hemipelagic glauconite-rich biomicrites that also contain planktic foraminifera and small stromatolites. Thirty-three ammonite species referred to 15 genera are described; the assemblage extends from the lower part of the Lower Cenomanian Mantelliceras mantelli Zone (Neostlingoceras carcitanense Subzone) to the lower part of the Middle Cenomanian Acanthoceras rhotomagense Zone (Turrilites costatus Subzone). The assemblage comprises 57 percent trachyostracous forms, 41 percent heteromorphs of the standard N.W. European sequence, and 2 percent leiostracous forms, which inhabited an external shelf biome. The biogeographic affinity of this fauna is essentially cosmopolitan (69 percent), but 31 percent of the specimens belong to the European Boreal biota, with no Tethyan tax

Aqueous solubilization of C60 fullerene by natural protein surfactants, latherin and ranaspumin-2

C60 fullerene is not soluble in water and dispersion usually requires organic solvents, sonication or vigorous mechanical mixing. However, we show here that mixing of pristine C60 in water with natural surfactant proteins latherin and ranaspumin-2 (Rsn-2) at low concentrations yields stable aqueous dispersions with spectroscopic properties similar to those previously obtained by more vigorous methods. Particle sizes are significantly smaller than those achieved by mechanical dispersion alone, and concentrations are compatible with clusters approximating 1:1 protein:C60 stoichiometry. These proteins can also be adsorbed onto more intractable carbon nanotubes. This promises to be a convenient way to interface a range of hydrophobic nanoparticles and related materials with biological macromolecules, with potential to exploit the versatility of recombinant protein engineering in the development of nano-bio interface devices. It also has potential consequences for toxicological aspects of these and similar nanoparticles