Effect of foliar‐applied potassium silicate on coffee leaf infection by Hemileia vastatrix

Coffee leaf rust, caused by Hemileia vastatrix, is the most devastating disease of coffee. Since limited information is available in the literature on silicon (Si) affecting plant diseases in coffee, this study was designed to investigate foliar application of potassium silicate (PS), a source of soluble (Si), on infection process of coffee leaf rust at the microscopic level. The foliar Si concentration for plants sprayed with water and PS has no significant difference (0.24 and 0.30 dag kg^?1, respectively). X‐ray microanalysis indicated that the deposition of Si on the leaves of the plants that were sprayed with PS was greater in comparison to the leaf samples from the plants sprayed with water. Rust severity on leaves of plants sprayed with water or sprayed with PS reached 44% and 32%, respectively, at 36 days after inoculation (dai). Plates of polymerised PS were observed on the leaf surfaces of the plants sprayed with the product, in contrast to its absence on the leaf surfaces of plants sprayed with water. At 36 dai, a greater number of uredia were observed on the leaf surfaces of plants sprayed with water in comparison to the leaf surfaces of plants sprayed with PS. On fractured leaf tissues that were sprayed with PS, less fungal colonisation was observed in comparison to the leaves of plants sprayed with water. In conclusion, the results of this study suggest that the effect of foliar‐applied Si on the control of the coffee leaf rust development may be attributed to the physical role of the polymerised PS, its osmotic effect against urediniospores germination, or both.     

β-adrenoceptors in human tracheal smooth muscle: characteristics of binding and relaxation

Specific binding of [¹²⁵I]-(−)-cyanopindolol to human tracheal smooth muscle membranes was saturable, stereo-selective and of high affinity (K_d=5.3±0.9 pmol/l and R_T=78±7fmol/g tissue). The β₁-selective antagonists atenolol and LK 203-030 inhibited specific [¹²⁵I]-(−)-cyanopindolol binding according to a one binding site model with low affinity in nearly all subjects, pointing to a homogeneous β₂-adrenoceptor population. In one subject using LK 203-030 a small β-adrenoceptor subpopulation could be demonstrated. The beta-mimetics isoprenaline, fenoterol, salbutamol and terbutaline recognized high and low affinity agonist binding sites. Isoprenaline's pK_H- and pK_L- values for the high and low affinity sites were 8.0±0.2 and 5.9±0.3 respectively. In functional experiments isoprenaline relaxed tracheal smooth muscle strips having intrinsic tone with a pD₂-value of 6.63±0.19.     

Imidazole antimycotics: selective inhibitors of steroid aromatization and progesterone hydroxylation

Econazole, imazalil, and prochloraz, which have broad spectrum antimycotic activity, are shown to be potent inhibitors of steroid aromatase activity of human placental microsomes. The IC50 values for the inhibition of aromatase activity by econazole, imazalil, miconazole, prochloraz, clotrimazole, ketoconazole, and aminoglutethimide are 0.03, 0.15, 0.6, 0.7, 1.8, 60, and 45 microM, respectively. Econazole and 4-hydroxyandrostenedione also inhibit the steroid aromatase activity of human fetal liver, a finding which suggests that extraplacental aromatase may have many similarities to the placental enzyme. Econazole is a more effective inhibitor of placental aromatization of 19-hydroxyandrostenedione than of androstenedione. This observation is consistent with the competitive nature of the inhibition of aromatase by imidazole antimycotic agents and the reduced affinity of the placental aromatase enzyme for 19-hydroxyandrostenedione compared to androstenedione. The effectiveness of these imidazole antimycotic agents to inhibit the multiple hydroxylations of progesterone which are catalyzed by human fetal adrenal microsomes is also defined. While all of the imidazole antimycotic agents are potent inhibitors of the 16 alpha-, 17 alpha-, and 21-hydroxylations of progesterone, selective inhibitory profiles are apparent. Ketoconazole is a most potent inhibitor of human fetal adrenal progesterone 16 alpha- and 17 alpha-hydroxylases while clotrimazole and imazalil are the most potent inhibitors of progesterone 21-hydroxylase. These results are strongly supportive that imidazole drugs are selective inhibitors not only of steroid aromatase but also of other microsomal steroid hydroxylases.     

Immunoaffinity-purified opiate receptor specifically binds the delta-class opiate receptor ligand, cis-(+)-3-methylfentanylisothiocyanate, SUPERFIT

Using an antibody generated against the opiate receptor on NG108-15 cells, we recently purified the putative receptor from this hybrid cell line. We herein report that the purified receptor complex specifically binds tritiated cis-(+)-3-methylfentanylisothiocyanate (SUPERFIT), with the predominant binding associated with a 58 kDa polypeptide chain. Consistent with these findings is the in situ labeling of a 58 kDa protein with [3H]SUPERFIT on NG108-15 cells.     

Methods of hatching the eggs and rearing the fundatrices of the English grain aphid, Sitobion avenae

Several methods for hatching the eggs and rearing individuals of the first generation (fundatrices) of Sitobion avenae were investigated. The most successful methods were incubation of the eggs on grass seedlings at 2°C and rearing the fundatrices on grass seedlings (overall survival 66%) and incubation of the eggs in plastic boxes at 2°C and rearing the fundatrices on wheat seedlings (overall survival 62%).

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Résumé L'éclosion des oeufs de S. avenae peut être induite par le transfert à 10°C ou 12°C, après une incubation de 75–120 jours à 2°C. Le pourcentage le plus élevé d'éclosions a été obtenu quand les oeufs avaient incubé pendant 100 à 110 jours à 2°C (67% at 71.5% respectivement) dans des petites boîtes de plastique, ou pendant 100 jours à 2°C sur des pousses de graminées (73.5%). Si les oeufs sont pondus sur blé, la plante ne peut pas tolérer la période d'incubation, mais cet obstacle peut être surmonté en obligeant les ovipares à pondre leurs oeufs sur de pousses de graminées, comme Poa annua, hôte convenable pour les fondatrices. Les ovipares peuvent aussi pondre sans difficultés sur autre chose que des végétaux, et des récipients peuvent ètre mis à incuber sans contenir du matériel végétal.

     

Localization and cloning of Xp21 deletion breakpoints involved in muscular dystrophy

Summary Twenty-nine deletion breakpoints were mapped in 220 kb of the DXS164 locus relative to potential exons of the Duchenne and Becker muscular dystrophy gene. Four deletion junction fragments were isolated to acquire outlying Xp21 loci on both the terminal and centromere side of the DXS164 locus. The junction loci were used for chromosome walking, searches for DNA polymorphisms, and mapping against deletion and translocation breakpoints. Forty-four unrelated deletions were analyzed using the junction loci as hybridization probes to map the endpoints between cloned Xp21 loci. DNA polymorphisms from the DXS164 and junction loci were used to follow the segregation of a mutation in a family that represents a recombinant. Both the physical and genetic data point to a very large size for this X-linked muscular dystrophy locus.