Phosphinothricin stimulates somatic embryogenesis in grape (Vitis sp. L.)

The effect of phosphinothricin concentration on embryo production from an embryogenic callus of Chancellor (Vitis L. complex interspecific hybrid) was tested. Embryogenic callus was cultured on medium supplemented with nine phosphinothricin concentrations (0, 0.1, 0.5, 1, 1.5, 2, 3, 5, and 10 mg/l). The highest number of embryos per plate was observed at 0.5 mg/l phosphinothricin. The use of phosphinothricin to stimulate embryo production did not affect embryo germination and plantlet formation. Three germination techniques were compared. Embryo dehydration or growth on Transfergelsolidified medium gave higher germination rates than chilling treatments. Most germinated somatic embryos produced secondary embryos from the hypocotyl after a few weeks of culture. Regardless of the germination technique, the plantlet conversion rate was very low.Abbreviations AC activated charcoal - 2,4-D 2,4-dichlorophenoxyacetic acid - BA 6-benzylaminopurine - MS Murashige and Skoog (1962) basal medium - NN Nitsch and Nitsch (1969) medium - PPT phosphinothricin     

Bacterial leader peptidase,a membrane protein without a leader peptide,uses the same export pathway as pre-secretory proteins

Leader peptidase typifies a group of proteins of the plasma membrane of E. coli which span the membrane and are synthesized without a cleaved amino-terminal leader (signal) sequence. The membrane assembly properties of these proteins have not been previously reported. We find that the membrane electrochemical potential is necessary for the insertion of a large domain of leader peptidase across the membrane. In the absence of potential, the peptidase accumulates inside the cell in tight association with the. plasma membrane. Upon restoration of the potential, accumulated peptidase inserts across the membrane, indicating that this insertion is not mechanistically coupled to polypeptide chain growth. The normal, trans-bilayer peptidase and that which accumulates in the absence of potential have different conformations, as shown by the relative resistance of the trans-bilayer enzyme to digestion by trypsin or chymotrypsin in cell lysates. Membrane insertion is accompanied by this conformational change. This assembly reaction has several features predicted by the hypothesis of membrane-triggered folding.     

Production of penicillins and cephalosporins in an immobilized enzyme reactor

Summary Four enzymes required for the biosynthesis of pencillins and cephalosporins by Streptomyces clavuligerus have been immobilized on an anion exchange resin. The capabilities of the system have been studied by circulation of reaction mixtures through the immobilized enzyme reactor. Within 30 min, all of the substrate -(l--aminoadipyl)-l-cysteinyl-d-valine is consumed and converted to a mixture of penicillins and cephalosporins. After 60 min the major antibiotic products are (iso)penicillin N and desacetylcephalosporin C. The activity of the immobilized enzyme reactor activity is stable to storage at temperatures below 4°C but activity is lost on repeated use.     

Protamines in plant sperm

Sperm protamines have been isolated from representatives of three major plant groups: algae (Chara corallina ), bryophytes ( Marchantia polymorpha), and ferns ( Marsilea vestitia ). We previously reported the complete displacement of histones by protamines in Marchantia (Reynolds W F & Wolfe, S L, Exp cell res 116 (1978) 269 [8] ). Marchantia protamines appear as four components on acid-urea gels, whereas Chara and Marsilea protamines comigrate as a single band with a mobility comparable to salmon protamine. The amino acid compositions of the plant protamines show these to be arginine-rich, highly basic (35-42%) proteins which display overall similarity in amino acid composition (84-91%). The molecular weights of Chara and Marsilea protamines are approx. 4700-5300 D.     

Determination of the solution conformation of adenosein 2':3'-monophosphate by nuclear magnetic resonance with lanthanide probes.

The aqueous solution conformation of adenosine 2':3'-monophosphate at pH 2.5 has been determined by a nuclear magnetic resonance method utilizing lanthanide ions as shift and relaxation probes. The ribose conformation is best described as a rapid equilibrium of 2'-endo(3'-exo) and 3'-endo(2'-exo) conformations in a ratio of approximately 2 to 1. The orientation of the base relative to ribose is restricted to a narrow range about chiCN=-70 degrees.     

Identification of tomato bushy stunt virus in cherry and plum trees showing fruit pitting symptoms

The fruit pitting symptoms on cherries, plums and prunes were investigated from the standpoint of their etiology. Tomato bushy stunt virus (TBSV) was isolated from pitted fruits of these plants and from their leaves and identified by means of biological and serological methods. Both isolates reacted with antisera againstPetunia and artichoke strain of this virus. In addition, the etiology of pseudopox disease of plum and that of cherry detrimental canker is discussed.     

Isolation of a cytomegalovirus from salivary glands of white-lipped marmosets (Saguinus fuscicollis).

Minced salivary glands from seven white-lipped marmosets (Saguinus fuscicollis and Saguinus nigricollis) and one cotton-topped marmoset (Saguinus oedipus) were cocultivated with marmoset cell cultures. A viral agent, designated SSG, was isolated from two Saguinus fuscicollis. Slowly progressing foci of rounded, vacuolated, refractile cells were first observed at 40-43 days incubation. Electron microscopy revealed intranuclear herpesvirus nucleocapsids and intracytoplasmic and extracellular enveloped particles. Infected cells stained with hematoxylin and eosin contained eosinophilic intranuclear and cytoplasmic inclusion bodies. SSG could be passaged in cell cultures only using viable whole cells; infectious cell-free virus was not detected in either culture supernatants or cell lysates. SSG replicated in marmoset fibroblastic but not in marmoset epithelioid or human fibroblastic cell cultures. Plasma antibodies to SSG were detected by indirect immunofluorescence assays in 16 of 56 (28.6%) adult wild-caught marmosets but were absent in 40 colony-born, hand-reared marmosets. Antigenic cross-reactivity of SSG with a rhesus monkey (Macaca mulatta) cytomegalovirus (bidirectional) and with a human cytomegalovirus (unidirectional) was also demonstrated by indirect immunofluorescence assays. SSG was identified as a herpesvirus by morphology and was classified as a cytomegalovirus by its site of isolation, biologic properties in vitro, and antigenic characteristics.     

Acetogenium kivui,a new thermophilic hydrogen-oxidizing acetogenic bacterium

Hydrogen-oxidizing acetogenic bacteria in pure culture are presently represented by the two mesophilic species, Acetobacterium woodii and Clostridium aceticum. From Lake Kivu we have isolated a Gram negative, chemolithotrophic, thermophilic anaerobe (LKT-1) that oxidizes hydrogen and reduces carbon dioxide to acetic acid. It is a non-motile, non-sporeforming rod, about 0.7m in width and 2–7.5m in length, often occuring in pairs or chains. The cell wall has a banded appearance; the surface layer contains a regular array of particles with six-fold rotational symmetry. No outer membrane is present. The temperature optimum for growth is 66°C, and the pH optimum is 6.4. Organic growth substrates include glucose, mannose, fructose, pyruvate, and formate; acetate is the principal product. The doubling time for growth on hydrogen and carbon dioxide is about 2h. Vitamins are neither required nor stimulatory. Yeast extract and Trypticase enhance the final yield but do not affect the growth rate. Cysteine or sulfide are required and cannot be replaced by thioglycolate or dithiothreitol. LKT-1 was mass cultured on hydrogen and carbon dioxide in a 24.1 fermentor with a yield of 34g (wet weight) of cells. The DNA base composition as determined by buoyant density is 38 mol % guanine plus cytosine. LKT-1 appears only distantly related to physiologically similar bacteria. A new genus Acetogenium is proposed, and the species is Acetogenium kivui.