Amylases during different stages of seed development in wheat

The β-Amylase activity was high in seeds of pre-Milk and milk stages but low in seeds of half seed and dough stages and very low at fully ripe stage of seed development. Zymogen (latent β-Amylase) was absent in half seed stage but appeared at pre-Milk stage. The content of zymogen increased progressively with advance in ripening time. No α-Amylase activity was detected at any stages of seed development in wheat.     

Population biology of Avena XI. Variation in peripheral isolates of A. barbata

Data on genetic polymorphism, scored at two morphological loci, showed peripheral, isolated roadside colonies of slender oat (Avena barbata) to be significantly less polymorphic than the large central populations in continuous stands. The role of random drift (founder effect) was evident in the genetic structure of such roadside colonies which were, however, not monomorphic. Multilocus associations also suggested large Hill-Robertson effect in generating gametic disequilibria. Such isolates with varying amounts of elapsed time since the founder events could offer useful material for a study of evolutionary processes including the selection-drift balance.     

Action of phospholipase A2 on unmodified phosphatidylcholine bilayers: Organizational defects are preferred sites of action

Summary The hydrolytic action of the bee venom phospholipase A₂ on phosphatidylcholine bilayers is studied under a variety of conditions that introduce alterations in the packing, such as those induced by sonication, gel to liquid crystalline phase transition, and osmotic shock. Two phases of hydrolysis could be resolved under a wide range of experimental conditions. With the various forms of the bilayers one observes only a partial hydrolysis of the total available substrate during the first phase. However, the fraction of the substrate hydrolyzed in the first phase changes with the form of the available substrate, with the amount of the enzyme added, with the temperature, with the phase transition characteristics of the substrate, and by the sonication of the substrate. The second phase of hydrolysis is generally observed when a certain concentration of the products has been produced during the first phase of hydrolysis. These observations are interpreted to suggest that the bee venom phospholipase A₂ preferentially catalyzes hydrolysis of the substrate available at or near the defects in the organization of the substrate in the bilayers.     

Removal of diacetyl from beer by adsorbants and diacetyl reductase

Removal of diacetyl from beer with adsorbants like cellulose, silica gel, activated charcoal, calcium phosphate gel, anion- and cation-exchange resins, and silicylic acid black soil bed (SABSB) was attempted in comparison with the enzyme diacetyl reductase (EC 1.1.1.5). Diacetyl could be removed from beer by the adsorbants but they had undesirable effect on the beer quality such as color, pH, and alcohol levels. These adverse effects were not observed with the use of diacetyl reductase. The results favor the enzymatic removal of diacetyl from beer as a superior approach.     

Variation inLimnanthes alba: A biosystematic survey of germ plasm resources1

Sixteen populations ofLimnanthes alba Bent ham are described for variation in plant growth, floral morphology, and reproductive traits in terms of a biosystematic survey of inter population differentiation. Earlier discussions of two varieties by other botanists are reviewed in relation to our findings of several overlapping and polymorphic population clusters (“races”). Afield evaluation of seed yield at Davis suggested that variability inL. alba be fully described for its use in crop improvement by hybridization and selection.     

Interaction of fluorinated ether anesthetics with artificial membranes.

Fluorine-19 nuclear magnetic resonance spectroscopy is applied to the study of the environment of dipalmitoyl phosphatidylcholine-bound fluorinated ether anesthetics (enflurane, fluoroxene and methoxyflurane) both below and above the lipid gel to liquid crystal phase transition temperature. Line widths and spin-lattice relaxation time (T1) measurements are consistent with substantial immobilization of the lipid-bound anesethetic molecules. Heating anesthetic/lipid mixtures above the lipid transition temperature leads to narrowing of the lipid-bound anesthetic fluorine resonances accompanied by little or no change in anesthetic fluorine-19 chemical shifts, suggesting that although the mobility of the bound anesthetic increases at the higher temperature, the nature of the anesthetic-lipid interaction changes little as a result of this phase change. Differential scanning calorimetric studies of the effects of these anesthetics on the phase transition behavior of the phospholipid indicate that the regions of the bilayer in which volatile anesthetics partition at lower concentrations are different from the regions in which they partition at higher concentrations.     

Population biology of avena. VI. The role of genetic polymorphisms in the outcome of interspecific competition

Three different series of population samples of two Avena species cooccurring in California were grown for an analysis of the role of genetic variation in interspecies competition: I, samples from mixed fatua-barbata sites in nature, grown in mixed stands; II, samples from pure sites and grown in pure stands, and III, the same sites as in II but grown in mixed stands. Four macroenvironments and four densities were used giving a total of sixteen entries for each genetic/competitive unit in order to measure both mean and variance of survival and reproductive rates as fitness characters. Sites used in each series included low versus high levels of genetic polymorphism within each species. In general, high polymorphism favored A. fatua in competition with monomorphic A. barbata, and high polymorphism in A. barbata allowed it to compete better with monomorphic A. fatua observation fits well into the pattern of reduced polymorphism in natural mixed stands. Mean performance of polymorphic mixed stands was not consistently higher than the monomorphic combinations or pure stands but the greater relative stability over environments seemed to favor polymorphisms in one or both of the competitors. A relatively less regular pattern of density or competitive response in series III was interpreted as evidence for the lack of coadaptedness between samples drawn from pure sites. Several limitations characteristic of such controlled studies were briefly discussed; however, the tentative conclusions from laboratory studies provided several promising clues for more critical field studies.This work was supported in part by a grant from the National Science Foundation (GB 8627).