Relationship of prodigiosin condensing enzyme activity to the biosynthesis of prodigiosin and its precursors in Serratia marcescens

Prodigiosin condensing enzyme (PCE) activities were present in Serratia marcescens wild type 08, mutants OF, WF and 9-3-3. Their specific activities exhibited different maxima and at different times during the late log phase or the early stationary phase of cell growth. The levels of prodigiosin and its precursors also showed a significant increase at this period. The results support that prodigiosin and/or its precursors are secondary metabolites. The ubiquity of the PCE activity in mutants deficient in prodigiosin biosynthesis suggest that this particular enzyme may also be present in non-pigmented clinical isolates.     

Dominance for enzyme activity inDrosophila melanogaster

Summary A regulatory element tightly linked to theGpdh locus inDrosophila melanogaster has been isolated from a natural population. Flies homozygous for second chromosomes bearing the element,H31, have half the GPDH activity of normal homozygotes. Heterozygotes betweenH31 andF orS alleles exhibit dominance in GPDH activity. Heterozygotes betweenH31, F orS andDf(2L) GdhA have half the diploid level. The contribution of theS allele to the activity inS/H31 heterozygotes is more than four times that ofH31. The regulatory element distinguishingH31 is tightly linked to theGpdh ⁺ locus.     

Cyanobacterial symbiont biosynthesis of chlorinated metabolites fromDysidea herbacea (Porifera)

The tropical marine spongeDysidea herbacea contains large numbers of a symbiotic filamentous cyanobacterium identified on the basis of a detailed ultrastructural study asOscillatoria spongeliae. We report the flow-cytometric separation of the symbiont from the sponge cells, and demonstrate by chemical analyses that a unique group of polychlorinated compounds isolated from the whole sponge tissue is limited to the cyanobacterial filaments, whereas the accompanying sesquiterpenoids are found only in the sponge cells. This is the first demonstration that secondary metabolites ascribed to a sponge are localized in prokaryotic symbiont cells.     

New tamjamine class alkaloids from the marine ascidianAtapozoa sp. and its nudibranch predators. Origin of the tambjamines inAtapozoa

Summary Two new tambjamine class alkaloids, possessing ichthyodeterrent properties, have been isolated from the organic extracts of the marine ascidianAtapozoa sp. and its nudibranch predators. The structure of the new metabolites were elucidated through interpretation of their physical and spectral data and by comparison with spectral data for related compounds. Microscopic examination ofAtapozoa considering the yellow color of the tambjamines suggested thatAtapozoa is capable of the de novo biosynthesis of these metabolites.     

Variation in regulation of aflatoxin biosynthesis among isolates ofAspergillus flavus

Two new phenotypes ofAspergillus flavus which exhibit novel patterns of aflatoxin production have been identified and characterized. In one of the new variants ofA. flavus, aflatoxin is made in the absence of carbohydrate and concomitantly with growth, without a lag period. A second variant did not produce aflatoxin in the presence or absence of carbohydrate. Chemical mutagenesis of this nonaflatoxigenic strain resulted in mutant strains which produced aflatoxin on carbohydrate-containing media. The aflatoxin production pattern observed in these mutants resembled the typical production scheme, with a lag period through log phase growth.     

Relationship between the absolute configuration and the biological activity of juvenile hormone III

Summary The activity of the pure 10R (=natural) and 10S enantiomers of juvenile hormone III (JH III) was determined in 3 different bioassays, and the relative binding affinity of the 2 enantiomers to the haemolymph JH-binding protein of the cockroachNauphoeta cinerea was measured. In theGalleria wax test, a local morphogenetic assay, the 10R enantiomer was 5240 times more active than, the 10S enantiomer, 1Galleria unit corresponding to 0.42 pg of 10R-JH III as compared to 2.2 ng for 10S-JH III. In a systemic morphogenetic assay with the cockroachNauphoeta cinerea 380 times less 10R enantiomer was necessary in order to induce detectable juvenilisation (58 ng 10R and 22 g 10S) and in a systemic gonadotropic assay withNauphoeta cinerea 255 times less 10R was needed to induce vitellogenin synthesis in 50% of the insects (6.7 ng 10R and 1710 ng 10S). In the JH-binding protein assay 10R-JH III had an affinity for the JH-binding protein (lipophorin) which was approximately 46 times higher than that of 10S-JH III.     

Effect of tingenone,a quinonoid triterpene,on growth and macromolecule biosynthesis inTrypanosoma cruzi

Summary Tingenone and horminone, two natural quinonoid substances, inhibited the in vitro growth ofTrypanosoma cruzi, 30 M drug concentration producing total inhibition of growth. Tingenone inhibited total uptake and incorporation of [³H]thymidine, [³H]uridine, L-[³H]leucine into parasite macromolecules. Other quinonoids assayed were either less effective (abruquinone A) or even quite inactive (visminone B and ferruginin B). Investigation of several mechanisms for the cytotoxic action of tingenone pointed to the interaction with DNA as the most likely factor involved. Tingenone also inhibited the growth ofCrithidia fasciculata, but the drug was significantly less active on this organism than onT. cruzi.This work was supported by grants of UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases, Organization of American States (Multinational Programme of Biochemistry) and Programa Nacional de Enfermedades Endémicas (SECYT), República Argentina. A preliminary account was given at the Workshop on Oxidative Damage and Related Enzymes, Frascatti (Italy), 1983.     

Two classes of metabolites fromTheonella swinhoei are localized in distinct populations of bacterial symbionts

The marine spongeTheonella swinhoei (lithistid Family Theonellidae, Order Astrophorida) has yielded many important, bioactive natural products, most of which share structural features with bacterial natural products. The presence of microbial symbionts inT. swinhoei has been reported, and it was originally suggested that the cytotoxic macrolide swinholide A and many of the bioactive cyclic peptides fromT. swinhoei were all produced by symbiotic cyanobacteria. By transmission electron microscopy, we found four distinct cell populations to be consistently present inT. swinhoei: eukaryotic sponge cells, unicellular heterotrophic bacteria, unicellular cyanobacteria and filamentous heterotrophic bacteria. Purification and chemical analyses of each cell type showed the macrolide swinholide A to be limited to the mixed population of unicellular heterotrophic bacteria, and an anti-fungal cyclic peptide occurred only in the filamentous heterotrophic bacteria. Contrary to prior speculation, no major metabolites were located in the cyanobacteria or sponge cells.     

Identification of a new predaceous stink bug pheromone and its attractiveness to the eastern yellowjacket

Summary Males ofPodisus fretus (Hemiptera: Pentatomidae) release a long-range attractant pheromone containing linalool (49.0%), (E)-2-hexenal (34.5%), benzyl alcohol (12.0%), nerolidol (2.0%),-terpineol (1.1%), and traces of several other compounds. The eastern yellowjacket,Vespula maculifrons (Hymenoptera: Vespidae), is attracted to artificial pheromones forP. fretus and for the sympatric species,Podisus maculiventris.The authors thank Mr T.J. Henry of the USDA Systematic Entomology Laboratory and Dr J.E. McPherson, Southern Illinois University, for examining the pentatomid species and Dr A.S. Menke, USDA-SEL, for determining the yellowjacket species. We also thank S. Wilzer for technical assistance. Mention of a company name does not imply endorsement by the US Department of Agriculture.     

Elucidation of the relationship between enzyme activity and internal motion using a lysozyme stabilized by cavity-filling mutations

We investigated the activity and the internal motions of a stabilized mutant hen lysozyme (HEL) in which the residues M12 and L56 were mutated to L and F, respectively (LF mutant HEL). The result of the activity measurements against glycol chitin at various temperatures suggested that the temperature dependence of the activity of LF mutant HEL shifted to the high-temperature side compared with that of wild-type HEL. The detailed internal motions of LF mutant HEL in the absence and presence of a substrate analogue, (NAG)₃, were examined by model-free analysis at 35°C. The results showed that the internal motions of LF mutant HEL in the presence of (NAG)₃ were drastically restricted compared with those in wild-type HEL. Our findings thus suggested that the mutation to the stabilized lysozyme restricted internal motions required for the enzymatic reaction.Received 8 February 2005; accepted 10 March 2005Y. Yoshida and T. Ohkuri contributed equally to this work.     

In vitro biosynthesis of juvenile hormone III by the corpora allata ofCalliphora vomitoria and its role in ovarian maturation and sexual receptivity

Summary JH III is the only JH detected by GLC-MS in medium from in vitro incubations of corpora allata of adult females ofCalliphora vomitoria. When corpora allata were removed from females at various times during the reproductive cycle and the JH III produced by the glands in vitro measured by a JH III radioimmunoassay, an increase in the level of synthesis was found to occur before previtellogenesis (0–24 h). A second increase appeared at the onset of vitellogenesis (72–83 h) and continued until the end of vitellogenesis (96 h) and the occurrence of chorionation (120 h). Since sexual receptivity develops with vitellogenesis, the significantly higher levels of JH III biosynthesis in vitro at this time supports a possible role for JH in the acquisitive of receptivity.     

Chromosome-breaking activity of extracts of the mushroomPaxillus involutus Fries ex Batsch

Summary Dry and presoaked seeds ofNigella damascena were treated with aqueous extracts of the mushroomPaxillus involutus. At the first mitosis after the onset of germination, metaphase chromosomes showed damage independent of the origin of the mushrooms. The damaging substance(s) is (are) thermostable. Except a few achromatic gaps, all the lesions observed are of the chromosome type, i.e. are induced at the pre-synthetic G1 stage.     

Recent observations on the structure and the properties of yeast NMN adenylyltransferase

Summary A homogeneous preparation of yeast NMN adenylyltransferase (EC 2.7.7.1) showed microheterogeneity, which was revealed by FPLC (Fast Protein Liquid Chromatography) ion exchange chromatography. The resolved components have been characterized with respect to electrophoretic behavior and adenine content. The results led to a hypothesis about a possible role of poly(ADP-ribosylation) in modulating the enzyme activity.     

Secondary metabolites of the chemically rich ascoglossanCyerce nigricans

Summary Two new metabolites of an apparent propionate origin have been isolated from the organic extract of the ascoglossan molluscCyerce nigricans. The proposed structures for the new natural products are based on interpretation of their physical and spectral properties. The new compounds isolated lacked the potent ichthyodeterrent properties of the whole animal extract suggesting that other molecules are involved in the defense of this shell-less mollusc.     

Partial purification and characterization of acid phosphatase from sporulated oocysts ofEimeria tenella

Summary Acid phosphatase ofEimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and V_max values for (Peak II) were 25 mM and 1.57 mol/min/mg protein, respectively. The enzyme (Peak II) ist strongly inhibited by Hg⁺⁺, Cu⁺⁺, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.     

Carbohydrase and esterase activity in the gut of larvalCallosobruchus maculatus

Summary Carbohydrase activity has been demonstrated in homogenates of the alimentary tracts of late instar larvae ofC. maculatus:-D galactosidase, -D glucosidase and N-acetyl-D glucosaminidase activities were comparable and significantly greater than -D galactosidase,-D glucosidase and -D mannosidase. The effects of pH and substrate concentration are reported. The presence and changes in pattern of non-specific esterase activity in larval and adult gut homogenates is also described.     

Aberrant,canavanyl protein formation and the ability to tolerate or utilize L-canavanine

Summary L-Canavanine, 2-amino-4-(guanidinooxy)butyric acid, and L-arginine incorporation into de novo synthesized proteins was compared in six organisms. Utilizing L-[guanidinooxy¹⁴C]canavanine and L-[guanidino¹⁴C]arginine at substrate saturation, the canavanine to arginine incorporation ratio was determined in de, novo synthesized proteins.Caryedes brasiliensis andSternechus tuberculatus, canavanine utilizing insects;Canavalia ensiformis, a canavanine storing plant; and to a lesser extentHeliothis virescens, a canavanine resistant insect, failed to accumulate significant canavanyl proteins. By contrast,Manduca sexta, a canavanine-sensitive insect, andGlycine max, a canavanine free plant, readily incorporated canavanine into newly synthesized proteins. This study supports the contention that the incorporation of canavanine into proteins in place of arginine contributes significantly to canavanine's antimetabolic properties.     

Transfer of secondary metabolites from the spongesDysidea fragilis andPleraplysilla spinifera to the mantle dermal formations (MDFs) of the mudibranchHypserlodoris webbi

The opisthobranch molluscHypselodoris webbi is able to select, among its potential preys, sponges chemically rich in furanosesquiterpenoids. The sequestered secondary metabolites act as defensive allomones against predators and are accumulated in some dorsal glands (MDFs). This transfer from sponges to MDFs has been proven by maintainingH. webbi together with some selected sponges in an aquarium for a prolonged period.