Cloning of aroG, the gene coding for phospho-2-keto-3-deoxy-heptonate aldolase(phe), in Escherichia coli K-12, and subcloning of the aroG promoter and operator in a promoter-detecting plasmid

Defective transducing phages carrying aroG, the structural gene for phenylalanine (phe)-inhibitable phospho-2-keto-heptonate aldolase (EC 4.1.2.15; previously known as 3-deoxy-D-arabinoheptulosonate-7-phosphate synthetase[phe]), have been isolated, and DNA from two of these phages has been used to construct a restriction map of the region from att lambda to aroG. A 7.6-kb PstI-HindIII fragment from one of these phages was cloned into pBR322 and shown to contain aroG. The location of aroG within the 7.6 kb was established by subcloning and Tn3 transpositional mutagenesis. A fragment carrying the aroG promoter and operator has been cloned into a high copy number promoter-cloning vector (pMC489), and the resulting aroGpo-LacZ' (alpha) fusion subcloned in a low copy number vector. Strains with this fusion on the low copy number vector exhibit negative regulation of beta-galactosidase expression by both phenylalanine and tryptophan and positive regulation by tyrosine in a tyrR+ background.     

Activation of fatty acids by non-glyoxysomal peroxisomes

Ethylene treatment (approx. 20 mg src="/content/jq1705n664310m00/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">l ·1^-1 in air for 2 d) of tobacco (Nicotiana tabacum L. cv. Havana 425) plants markedly increases the endo-mg src="/content/jq1705n664310m00/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-1,3-glucanase (EC 3.2.1.39) content of leaves. The antigenic form of the enzyme induced is the same one whose production is blocked by treating cultured cells with combinations of auxin (1.1 · 10^-5 M mg src="/content/jq1705n664310m00/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-naphthaleneacetic acid) and cytokinin (1.4 · 10^-6 M kinetin). Evidence is presented that cultured tobacco cells require ethylene for mg src="/content/jq1705n664310m00/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-1,3-glucanase accumulation: i) ethylene treatment increased the accumulation of \-1,3-glucanase in callus tissues >10 d after subculturing and in cell-suspension cultures; ii) callus tissues can produce ethylene; iii) conditions known to inhibit ethylene production (1 mM CoCl₂; 33° C treatment) or ethylene action (approx. 1.6 mmol · 1^-1 norbornadiene in air) inhibited mg src="/content/jq1705n664310m00/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-1,3-glucanase accumulation by callus tissues treated for 4 d following subculturing; and, these inhibitory effects were prevented by exogenous ethylene. Combinations of auxin and cytokinin blocked ethylene-induced accumulation of mg src="/content/jq1705n664310m00/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-1,3-glucanase by cell-suspension cultures. The results favor a model in which ethylene induces results favor a model in which ethylene induces mg src="/content/jq1705n664310m00/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0"> 1,3-glucanase accumulation, and auxin and cytokinin inhibit this induction process.Abbreviations NAA mg src="/content/jq1705n664310m00/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-naphthaleneacetic acid - NDE norbornadiene     

Les régulateurs de croissance d'insectes (RCI), mimiques de l'hormone juvénile,en tant que moyen de lutte morphogénétique et ovicide contre les tordeuses des vergers

Résumé La métamorphose des insectes est régie par un équilibre hormonal complexe dans lequel l'hormone juvénile (HJ) joue un rôle important. Au dernier stade larvaire, la teneur en HJ est particulièrement faible dans le corps de l'insecte. Si un régulateur de croissance d'insectes (RCI)-un mimétique de l'HJ-est appliqué à ce moment-là, la mue nymphale est pertubée provoquant des déformations morphogénétiques caractéristiques. La teneur en HJ est également très faible dans les mg src="/content/x148030m3l175501/xxlarge339.gif" alt="oelig" align="BASELINE" BORDER="0">ufs fraîchement pondus. Les traitements aux RCI peuvent par conséquent perturber le développement embryonnaire de certaines espèces et produire ainsi un effet ovicide. Depuis quelques années deux RCI-le fenoxycarb et le CGA 45mg src="/content/x148030m3l175501/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0"> 128-ont été testés pour leur activité morphogénétique sur le dernier stade larvaire de quelques ravageurs tels qu'Adoxophyes orana F.v.R., ainsi que pour leur activité ovicide sur les mg src="/content/x148030m3l175501/xxlarge339.gif" alt="oelig" align="BASELINE" BORDER="0">ufs frais de Cydia pomonella L. et Grapholita funebrana Tr. Après quelques années d'expérimentation et de commercialisation des RCI dans les vergers européens, il s'avère que l'utilisation de ces produits peu toxiques, sélectifs et peu nocifs pour la faune utile, constitue une amélioration considérable pour l'aménagement de la lutte intégrée.

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Insect growth regulators (IGR), mimics of juvenile hormone, as morphological and ovicidal means of control against orchard tortricids

Summary Metamorphosis is regulated by a complex hormonal balance in which juvenile hormone (JH) plays an important part. At the last larval instar the content of JH is particularly low in the insect body. If an insect growth regulator (IGR) — a mimic of JH-is applied at this time, the pupal moult may be disturbed with the characteristic morphogenetical deformations. The JH content is also very low in freshly laid eggs. Therefore IGR treatments may disturb the embryonic development of some species and produce an ovicidal activity. During a few years two IGR-fenoxycarb and CGA 45mg src="/content/x148030m3l175501/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">128-were evaluated for their morphogenetical effect on the last larval instar of Adoxophyes orana F.v.R. and their ovicidal effect on freshly laid eggs of Cydia pomonella L. and Grapholita funebrana Tr. After a few years of experimentation with both compounds and of commercialisation of fenoxycarb in European orchards, IGR confirmed to present a considerable improvement in integrated pest management due to selectivity, and low mammal toxicity.

     

Core substructure in Mastigocladus laminosus phycobilisomes

A native high molecular complex (M_r 850000) containing about 50% of the allphycocyanin of the phycobilisome but lacking allophycocyanin B was separated from isolated phycobilisomes by gel electrophoresis. It was designated AP_CM since the large linker polypeptide L_CM was exclusively localized in this complex. The complex exhibited a ?196°C fluorescence emission maximum at 673 nm (671 nm at 25°C). In addition, a core complex (designated AP_C, M_r≥1000000) consisting of both AP_CM and AP 680 was isolated by combined gel filtration and linear gradient centrifugation. At 25°C this complex showed dual emission peaks at 670 and 680 nm demonstrating functional independence of the terminal emitters. A complex similar to AP_CM can be isolated from phycobilisomes of m>Anabaena variabilism>. This is evidence that AP_CM is the constitutive center of the tricylindrical core of hemidiscoidal cyanobacterial phycobilisomes. Two models summarizing the structural and functional consequences of the results are presented in the discussion.     

Role of the N-terminal region of the A chain in beta 1-bungarotoxin from the venom of Bungarus multicinctus (Taiwan-banded krait)

The N-terminal mg src="/content/u0130747188m342r/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-amino groups of mg src="/content/u0130747188m342r/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-bungarotoxin (mg src="/content/u0130747188m342r/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-Bgt) fromBungarus multicinctus venom were modified with trinitrobenzene sulfonic acid and the modified derivative was separated by high performance liquid chromatography. The trinitrophenylated (TNP) derivative contained two TNP groups at the mg src="/content/u0130747188m342r/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-amino groups of A chain and B chain and showed a marked decrease in enzymatic activity. Methionine residues at positions 6 and 8 of the A chain were oxidized with chloramine T or cleaved with cyanogen bromide to remove the N-terminal octapeptide. Oxidation of methionine residues and removal of the N-terminal octapeptide caused a precipitous decrease in enzymatic activity, whereas antigenicity remained unchanged. The presence of dihexanoyllecithin influenced the interaction between mg src="/content/u0130747188m342r/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-Bgt and 8-antilinonaphthalene sulfonate (ANS) and revealed that mg src="/content/u0130747188m342r/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-Bgt consists of two types of ANS-binding sites, one at the substrate binding site of the A chain and the other might be at the B chain. The modified derivatives still retained their affinity for Ca²⁺ and ANS, indicating that the N-terminal region is not involved in Ca²⁺ and substrate binding. A fluorescence study revealed that the mg src="/content/u0130747188m342r/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-amino group of the A chain was in the vicinity of substrate binding site and that the TNP mg src="/content/u0130747188m342r/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-amino groups were in proximity to Trp-19 of the A chain. In addition, the study showed that the N-terminal region is important for stabilizing the architectural environment of Trp-19. The results, together with the proposal that Trp-19 of the A chain is involved in substrate binding, suggest that the N-terminal region of the A chain plays a crucial role in maintaining a functional active site for mg src="/content/u0130747188m342r/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">₁-Bgt.     

Nitrite reduction in Bacteroids of Rhizobium “hedysari” strain HCNT 1

Ex planta, bacteroids of the sulla-symbiont Rhizobium mg src="/content/m66472w104718766/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">hedysarimg src="/content/m66472w104718766/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> strain HCNT 1 terminated reduction of nitrite at nitrous oxide irrespective of the presence or absence of acetylene. Nitrate was not reduced during the experimental period, but slight nitrate reductase activity occurred if incubation with nitrate was prolonged (up to 15 h). As was observed in free-living cells, exposure of the bacteroids to the metal chelator, diethyldithiocarbamate, prevented reduction of nitrite, indicating the presence of a copper-containing nitrite reductase. Pulses of 10–75 mg src="/content/m66472w104718766/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M nitrite transiently impeded O₂ uptake in bacteroids, which resumed consumption of O₂ when the nitrite had been reduced. Exposure to >1.0 mM nitrite for 24h greatly inhibited nitrogenase activity (assayed as acetylene reduction activity) of bacteroids in planta. Exposure to the same concentrations of nitrite after 1h of incubation in the presence of acetylene almost completely stopped ongoing ethylene production in bacteroids of strain HCNT 1 extracted from nodules. Free cells of the non-nitrite-reducing R. mg src="/content/m66472w104718766/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">hedysarimg src="/content/m66472w104718766/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> strain CC 1335 were lacking in nitrogenase (acetylene-reduction) activity, whereas identically cultured (low-oxygen) strain HCNT 1 cells reduced both nitrite and acetylene.Abbreviations PMS phenazine methosulfate - DDC diethyldithiocarbamate     

Proteolytic specificity of chicken cathepsin L on bovineβ-casein

The proteolytic specificity of chicken cathepsin L was studied using bovine mg src="/content/h5n4453m0v362702/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-casein as substrate. The peptide mixtures obtained after various times of hydrolysis were separated by RP-HPLC and ten peptides were identified. Chicken cathepsin L accepts proline residues in all positions except P ₁ ^{mg src="/content/h5n4453m0v362702/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">} . Looking at the amino acid residues on the amino side of the scissile bond we found three times the Tyr-Pro pair at P ₁ ^{mg src="/content/h5n4453m0v362702/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">} –P ₂ ^{mg src="/content/h5n4453m0v362702/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">} positions and that the S ₁ ^{mg src="/content/h5n4453m0v362702/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">} subsite can interact with modified amino acids such as phosphoserine.Abbreviations RP-HPLC reverse phase high performance liquid chromatography - NMec N-methyl coumarylamide - TEA triethylamine - TFA trifluoroacetic acid     

The flight and landing of tsetse (Glossina) in response to components of host odour in the field

ABSTRACT. Studies were conducted in Zimbabwe of the responses of Glossina morsitans morsitans Westwood and Glossina pallidipes Austen to various host odours using either arrangements of electrocuting nets or visual observations. Tsetse flying upwind in a plume of carbon dioxide, acetone and octenol turned downwind upon flying into a plume of acetone or octenol, but did not turn upon flying into a plume of carbon dioxide. They also turned in response to a transient decline in odour concentration. Tsetse landed on the ground in the vicinity of a source of natural odour or artificial odour containing carbon dioxide but not at sources of acetone or octenol only. The proportion of female G.pallidipes caught at a source of natural odour (37%) was significantly different from that caught at a source of synthetic odour (17%). Resting tsetse stimulated by natural odour took off sooner than non-stimulated flies and had a strong upwind bias in the direction of take off. Tsetse stimulated with artificial odour did not take off sooner than non-stimulated flies. It is suggested that there is an unidentified components) of ox odour that activates resting tsetse.     

The intrinsic rates of increase of insects of different sizes

ABSTRACT.

• 1 A negative relationship between intrinsic rate of increase, r, and body size has only clearly been shown using data for species drawn from a number of phyla and covering several orders of magnitude in size. Analyses for more closely related species are equivocal.
• 2 Data for ninety-one species of insects, from nine orders, were used to examine the correlation between intrinsic rate of increase and size.
• 3 Intrinsic rate of increase was negatively correlated with both length and weight across orders, but no relationship could be shown within orders.
• 4 Generation times were positively related to body size, but there was no relationship between net reproductive rate (R_Q) and size.
• 5 These results support the hypothesis that documented relationships between species size and colonization success in insects could be a consequence of the scaling of intrinsic rate of increase with size.

     

Correlation of physical maps and some genetic functions in the genomes of the kappa-theta phage family of Bacillus licheniformis

Summary Natural recombinant genomes between several, phenotypically distinct forms of phages mg src="/content/m4850g254163206m/xxlarge954.gif" alt="kappa" align="BASELINE" BORDER="0"> and mg src="/content/m4850g254163206m/xxlarge977.gif" alt="thetav" align="BASELINE" BORDER="0"> were isolated and characterized by DNA restriction fragment mapping and electron microscopic heteroduplex analysis. The phenotypes of the recombinants were correlated with the physical maps of the genomes, and several genetic functions were therfore defined and mapped. All genes necessary for the assembly of infectious virus particles map in a contiguous tract of DNA comprising about 20 kb, or nearly one third of the genome length. No DNA homology occurs within these domains of the two genomes, so that homologous recombination does not take place here and phenotypic mixing of the phages is eo ipso excluded. Other regions of heterology contain regulatory genes responsible for the lytic or temperate character of the phages, and for exclusion of phage mg src="/content/m4850g254163206m/xxlarge954.gif" alt="kappa" align="BASELINE" BORDER="0"> by mg src="/content/m4850g254163206m/xxlarge977.gif" alt="thetav" align="BASELINE" BORDER="0">.