Microbial transformations of galanthamin-precursors

Summary Galanthamin is a medical important alkaloid. Its chemical synthesis gives a racemic product in low yields. Starting with a belladinderivative an enzymatic ring closure should lead exclusively to a chiral product possibly with the native structure. Although this reactions type is unknown in preparative biotransformations a large number of microorganisms were tested, unfortunately without success. On the other hand in the screen transformation products were found resulting from specific dealkylations of the subtrate. The type of metabolite formed was dependent on the fungi utilized for the transformation. Additionally two N-oxides were formed by Septomyxa affinis, one in good yield. It is possible that the chirality of this compound can direct the ring closure preferentially or exclusively to the desired stereoisomer of narwedine.     

Fusion-mediated injection of SV40-DNA : Introduction of SV40-DNA into tissue culture cells by the use of DNA-loaded reconstituted Sendai virus envelopes

Sendai virus envelopes can be solubilized by non-ionic detergents such as Triton X-100. Removal of the detergent from a supernatant containing the solubilized viral envelope glycoproteins results in the formation of reconstituted fusogenic viral envelopes. When SV40-DNA is added to the reconstitution system, it is trapped within the viral envelope. Incubation of SV40-DNA-loaded Sendai virus envelopes with permissive cells (CV1 and TC7 cells) resulted in fusion-mediated injection of the trapped DNA, as was demonstrated by the ability of the injected cells to synthesize SV40-T-antigen. Quantitative estimation revealed that up to 20% of the injected cells were able to synthesize T-antigen. Loaded viral envelopes were able to inject SV40-DNA and to promote synthesis of T-antigen also in cells which are resistant to infection by intact SV40 viruses, such as F1' 1-4 cells. In addition, it is shown that reconstituted envelopes of Sendai virus are able to transfer membrane fragments from SV40 receptor-positive into SV40 receptor-negative cells, such as F1' 1-4 cells. After implantation of SV40 receptors, the F1' 1-4 cells became susceptible to infection by intact SV40 viruses.     

Correlative changes in sucrose uptake, ATPase activity and membrane fluidity in carnation petals during senescence

Apparent sucrose uptake. ATPase activity and membrane fluidity changes were studied during the development and senescence of carnation flowers ( Dianthus caryophyllus L., cv. Cerise Royallette). Typical changes associated with senescence of a cut flower, such as respiration, ethylene production and fresh weight, were measured. Concomitant with a rise in respiration and ethylene production and a decline in fresh weight, a sharp decrease in apparent sucrose uptake was observed. Sucrose uptake was pH dependent (pH optimum, 5.5) and influenced by membrane integrity. Apparently, the activity of ATPase is related to sucrose uptake, because similar changes occurred during flower development. In addition, the activity of ATPase was well correlated with membrane fluidity.
It is suggested that sucrose uptake is controlled by ATPase activity, which in turn is modulated by membrane lipid fluidity. The decline in membrane fluidity associated with senescence leads to a corresponding reduction in ATPase activity and sucrose uptake. Further evidence supporting this view comes from experiments in which senescence was enhanced by 1-aminocyclopropane-l-carboxylic acid. It shortened the time to decline in fresh weight, rise in respiration and ethylene production. In parallel, reduction in membrane fluidity, ATPase activity and sucrose uptake were observed.     

Temperature sensitivity of complementation at the Maroonlike eye color locus in Drosophila melanogaster

Summary In contrast to the wild-type eye color seen when Drosophila melanogaster heterozygous for mal ¹/mal ^F1 are cultured at 25 C, a mutant eye color is observed in heterozygotes cultured at 29–30 C throughout development. Furthermore, heterozygotes have wild-type eyes upon emergence provided development proceeds at 25 C during either of two critical periods: 1) The third quarter of the 3rd larval instar or 2) an imprecisely defined pupal period beginning less than 12 hours before the visual appearance of brown eye pigment and terminating about the time pigment appears in the wings.     

Isolation and Characterization of Rifampin-Resistant and Streptolydigin-Resistant Mutants of Bacillus subtilis with Altered Sporulation Properties

Mutants of Bacillus subtilis with altered deoxyribonucleic-dependent ribonucleic acid polymerase activity have been isolated and characterized. These mutants, selected as strains resistant to rifampin or streptolydigin, demonstrate drug-resistant in vitro ribonucleic acid synthesis. Sporeforming ability and support of phage infection are altered in many of the mutants. Mutations to rifampin and streptolydigin resistance have been located on the B. subtilis chromosome and ordered relative to the markers cysA14 and str.     

Dosage Compensation of Genes on the Left and Right Arms of the X Chromosome of DROSOPHILA PSEUDOOBSCURA and DROSOPHILA WILLISTONI

We have investigated the occurrence of dosage compensation in D. willistoni and D. pseudoobscura, two species whose X chromosome is metacentric with one arm homologous to the X and the other homologous to the left arm of chromosome 3 of D. melanogaster. Crude extracts were assayed for isocitrate dehydrogenase (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?), and α-glycerophosphate dehydrogenase (chromosome 2) in D. willistoni, and for esterase-5 (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?) and amylase (chromosome 3) in D. pseudoobscura. Our results indicate that a mechanism for dosage compensation is operative in both arms of the X chromosome of these two species.     

Attraction and attachment of zoospores of the parasitic chytridRozella allomycis in response to host-dependent factors

Summary This study examined the behavior of populations of zoospores of the obligately parasitic, endobiotic chytridRozella allomycis towards young, vegetative thalli of various saprophytic fungi, in order to identify host-dependent factors which control the development ofRozella. An inverted microscope was employed for continuous observation of parasite-host interaction in petri dishes of broth or agar medium. Two factors appear to control the initial stages of invasion byRozella of both susceptible and resistant species of the host genus,Allomyces: (i) a soluble exudate which attractsRozella zoospores, (ii) a receptor on the cell-wall surface which causesRozella zoospores to adhere, and to encyst and to germinate immediately thereafter. A related, nonsusceptible species,Blastocladiella emersonii, also attractsRozella zoospores, but supports very limited attachment.Rozella zoospores neither accumulate around, nor adhere to young thalli of non-blastocladialean fungi. This host-specific behavior pattern is compared with that of saprophytic and facultatively parasitic Phycomycetes, whose zoospores show nonspecific chemotactic responses and require no receptor for attachment, encystment and germination.     

Conformational changes in the extracellular β-lactamase I from Bacillus cereus 569/H/9

1. The thermal denaturation and precipitation of beta-lactamase I from Bacillus cereus 569/H/9 at 60 degrees C are reversible, a soluble and almost fully active enzyme being obtained after solution of the precipitate in 5m-guanidinium chloride or 8m-urea and subsequent removal of the denaturing agent. 2. Inactivation of beta-lactamase I occurs rapidly between 50 degrees and 55 degrees C and is shown by circular-dichroism spectra to be accompanied by an extensive conformational change. 3. A change to a different conformation occurs in 6m-urea. This change is also reversible; refolding with almost complete recovery of enzymic activity occurs within 5min of dilution of the denaturing agent. 4. Inactivation of beta-lactamase I at pH3.0 and 11.0 is also associated with conformational changes, since a proportion of the lost activity is recovered within 5min of adjustment of the pH to 7.0.