Extraction of Endogenous Ethylene and Ethane from Leaves of Phaseolus vulgarisL.

A procedure to recover small volumes of gases from plant tissuesby vacuum extraction is described. Changes in the volume ofthe gases and the concentrations of ethylene and ethane recoveredfrom Phaseolus leaves were observed when the evacuation conditionsduring extraction were altered. These changes were differentin the primary leaves and in the second trifoliate leaves. Thus,estimates of internal ethylene and ethane concentrations appearto be influenced both by the morphology of the tissue and theevacuation conditions employed. There was a positive correlationbetween the concentrations of ethylene and ethane in the gaseousextracts. The internal ethylene concentrations in the primary,first trifoliate, and second trifoliate leaves, considered together,were correlated with their respective rates of ethylene emanation.     

Aspects of petroleum hydrocarbon metabolism in marine animals

Studies on hydrocarbon composition of Black Sea musselsMytilus galloprovincialis sampled from different habitats indicate that the quantity and composition of hydrocarbons distributed in the molluscs depend on season and sea-water quality. The data obtained under experimental conditions testify to the possibility of hydrocarbon concentration in mussel tissues after death. During filtration in sea water containing oil and oil products, these pollutants are bound into faeces and pseudofaeces which contain a greater percentage of aromatic compounds than the oil initially present in sea water. Quantitative data are presented on hydrocarbon changes in mussel excretory products during transfer from oil-polluted to clean sea water. When Black Sea crabsEriphia verrucosa are fed with mussels containing fuel-oil components accumulated from sea water, the pollutants concentrate in the whole body of the crab. This is in contrast to parenteral oil uptake, which leads to a concentration of most of the hydrocarbon in the muscles.     

Immobilization of microbial cells in crosslinked,prepolymerized, linear polyacrylamide gels: Antibiotic production by immobilized Streptomyces clavuligerus cells

A mild new method for the immobilization whole microbial cells has been developed. Cells were suspended in a solution of preformed, linear, water-soluble Polyacrylamide chains, partially substituted with acylhydrazide groups. The Prepolymerized backbone polymer was crosslinked, in the presence of viable cells, by stoichiometric amounts of dialdehydes such as glyoxal, glutardialdehyde, and period ate-oxidized polyvinyl alcohol. The crosslinking reaction, carried out in cold, neutral physiological conditions resulted in cells entrapped in gels with physical properties similar to those of the common Polyacrylamide gels. However, cell damage generally caused by the acrylamide monomer was avoided. Resting Streptomyces clavuligerus cells, possessing a high capacity for antibiotic production, were entrapped according to this procedure. These immobilized cells produced cephalosporins continuously for 96 h with yields similar to those of free resting cells. The same cells, when immobilized by direct polymerization acrylamide monomers, yielded significantly lower amount of antibiotics.     

Predicted mode of intercalation of doxorubicin with dinucleotide dimers

Intermolecular molecular mechanics energy calculations have been carried out for doxorubicin interacting with two dinucleotide dimer sequences. The preferred mode of intercalation is in the minor groove with the anthraquinone ring of the drug nearly perpendicular to the base pairs for the (CpG) sequence having alternate C3′ endo-C2′ endo sugar ring puckering. The preferred intercalation conformation of the drug is nearly identical to the N-bromacetyldaunomycin crystal structure. This prediction is qualitatively consistent with the recently reported crystal structure of a d(CpGpCpGpCpG) dimer-daunomycin complex. For the other dinucleotide sequence, (TpC-ApG), minor groove intercalation is also preferred, but the drug conformation can be changed.     

Size of vasopressin receptors from rat liver and kidney

Specific vasopressin receptors in rat liver membranes were recently characterized [Cantau et al., Journal of Receptors Research, in the press]. They differ from the receptors characterized earlier in kidney membranes as regards coupling with adenylate cyclase and specificity towards vasopressin structural analogues [Rajerison et al. (1974) J. Biol. Chem. 249, 6390-6400; Butlen et al. (1978) Mol. Pharmacol. 14, 1006-1017]. The object of the present work was to see whether these differences reflect a difference in the molecular size of liver and kidney vasopresin receptors. For this purpose, rat liver and kidney membranes were incubated with [3H]vasopressin and solubilized with Triton X-100 (0.3%). The properties of the macromolecular components of soluble extracts to which labelled vasopressin remained bound were observed to resemble those of the intact membrane receptors as regards binding reversibility at 30-37 degrees C and sensitivity to guanyl nucleotides. The hydrodynamic parameters of the soluble hormone-receptor complexes were estimated from Utrogel column filtration experiments and from sucrose density gradient ultracentrifugation experiments. The following values were obtained for liver and kidney receptors respectively: Stokes' radii: 5.4 and 5.6 nm; standard sedimentation coefficients: 3.7 and 3.7 S; partial specific volumes: 0.75 and 0.78 ml x g-1; molecular weight: 83000 and 80000. These results indicate that the marked functional differences between liver and kidney receptors are not accompanied by appreciable differences in molecular size.     

Earthworm (Pheretima communissima and Pheretima hilgendorfi) hemoglobins: giant assemblies and subunits

The molecular architecture of hemoglobins and their subunits of the earthworms Pheretima communissima and Pheretima hilgendorfi was investigated. In both species, their s0.20,w of 60.8 S and D020,w of 1.80 . 10(-7) cm2 . s-1 corresponded to a molecular weight of 3.07 . 10(6). From electron microscopic observations, the overall structure of the hemoglobins was shown to be two superimposed hexagonal discs, each composed of six-membered constituents. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of both hemoglobins revealed the presence of five species of subunits with molecular weights of 13,000-14,000 (subunit 1), 27,000-28,000 (subunit 2), 30,000-31,000 (subunit 3), 33,000-34,000 (subunit 4) and approx. 52,000 (subunit 5), respectively, and the molar ratio of these subunits 1:2, 3, 4:5 was 2:3:3. If we consider this set of the subunits 1 to 5 as one unit, the molecular weight of this unit should be 2.7-2.8 . 10(5). This one unit, therefore, should be considered to represent one-twelfth the whole molecule with molecular weight of 3.07 . 10(6).