High-throughput screening reveals small molecule modulators inhibitory to Acidovorax citrulli

Acidovorax citrulli is a seed-transmitted gram-negative bacterium that can cause substantial economic yield loss in watermelon and melon production worldwide. Four small-molecule libraries containing 4,952 compounds were selected for high-throughput screening against A. citrulli wild-type strain Xu3-14 by evaluation of growth inhibition. One hundred and twenty-seven molecules (2.5% hit rate) were identified as bactericidal or bacteriostatic against A. citrulli at 100 μM. Secondary screens indicated that 27 candidate compounds were more effective against A. citrulli Group II strains than Group I strains (classified using repetitive element PCR). Several compounds were inhibitory to other pathogenic bacteria, including Clavibacter michiganensis subsp. michiganensis and Xanthomonas campestris pv. campestris, but did not affect the growth of plant beneficial bacteria Pseudomonas fluorescens and Bacillus subtilis. More than half of the compounds did not inhibit germination of Arabidopsis or watermelon seeds. The effect of small molecules on A. citrulli seed-to-seedling transmission was evaluated by applying each compound to inoculated watermelon seeds and assessing seedling infection. Nine compounds were chosen for further investigation based on their reduction of percentage seedling infection and compiling scores on their specificity, sensitivity, and phytotoxicity obtained in the secondary screens. The five best compounds were selected (thiamphenicol, nadifloxacin, pipemidic acid, ciclopirox, and zinc pyrithione) for greenhouse tests and were found to effectively reduce the seed-to-seedling transmission of A. citrulli in both artificially and naturally infested seeds. These top five compounds provide a basis for future development of an A. citrulli-specific bactericide.     

Mycological studies on the wood-borerstromatium fulvum vill. (Col., cerambycidae) infestingcasuarina glauca (casuarinaceae) III. Effect of inoculation with the fungal isolates on lignin and extractive content of wood

Wood specimens of Casuarina glauca were inoculated withChaetomium spp. andTrichoderma spp., alone or in combination in the presence or abscence of larvae ofStromatium fulvum. All fungal inoculates caused deterioration to the lignin of the wood specimens. The infestation with larvae alone caused the same. The extractive content decreased to a little extent.

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Zusammenfassung Bäume von Casuarina glauca wurden mitChaetomium spp. undTrichoderma spp. inokuliert, allein oder in Kombination sowie in Abwesenheit oder Gegenwart der Larven vonStromatium fulvum. Alle Pilz-Inokulate verusachten einen Abbau von Lignin in den Bäumen. Denselben Effekt hatte die Tätigkeit vonStromatium-Larven ohne Pilz-Inokulation. Der extraktive Anteil verminderte sich nur wenig.

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With 2 tables     

Molybdate sorption by oxides of aluminium and iron

The sorption of molybdate by goethite, hematite, bayerite and α-Al₂O₃ was studied as a function of molybdate concentration and pH. The sorption isotherms exhibited double sorption plateaus in which the amount of Mo sorbed in the second plateau was double that in the first. This was attributed to the polymerization of molybdates as the concentration increases. Furthermore Mo sorption was found to be associated with a cosorption of Na cations, probably present to maintain electroneutrality in the surface zone. The sorption showed high sensitivity towards the pH, attaining a maximum at pH 4. For the iron oxides the decrease in sorption was much less pronounced on the acid side of the pH maximum and occured at lower pH values than that of the Al oxides. Molybdate sorption is explained in terms of a ligand exchange reaction between molybdate and surface hydroxyls.     

Effect of suspension concentration on quinoline adsorption onto Ca-montmorillonite

Quinoline adsorption onto Ca-montmorillonite was studied as a function of quinoline and clay concentrations. At constant quinoline concentration, the adsorption decreased as the clay concentration increased in the suspensions. This decrease was attributed to the increase in calcium concentration in solution, associated with the increase in clay concentration, and its effect on the Ca-quinoline exchange equilibria. The results were described by a Langmuir type adsorption equation expanded to cover exchange sorption of cation quinoline.     

Ultrasonographic study of early embryonic loss induced by Actinomyces pyogenes in cattle.

Four cows were inoculated into the uterus with Actinomyces pyogenes between 30 and 41 days of gestation. Gross morphological changes were monitored by rectal palpation and with a realtime B-mode two-dimensional scanner with a 7.5 MHz transrectal linear transducer, shortly before infection and afterwards at three to 12 hours intervals. Two control groups of cows 27 to 50 days pregnant were used: two cows were inoculated with 6 ml of sterile saline into the uterine lumen and four cows were treated with cloprostenol (prostaglandin F2 alpha analogue). There was a change in the uterine fluid from a black, non-echogenic image before infection to a grey or cloudy echogenic image as early as 21 hours after infection. There was an increase in the thickness of the endometrium of the horns and body of the uterus. The embryonic membranes thickened and separated from the endometrium as early as four hours after infection, followed by cessation of the embryonic heart beat, opening of the cervix and abortion. Abortion was followed by an increase in the amount of echogenic intrauterine fluid leading to an increase in the size of the uterus, and the cervix remained open for at least eight days. The area of the corpus luteum remained greater than 2 cm2 throughout the whole period. Intrauterine inoculation with sterile saline had no effects, but the administration of cloprostenol was followed by the death of the embryo and abortion within 72 hours, and the regression of the corpus luteum from greater than 2 cm2 at treatment to 0.4 cm2, 24 hours after abortion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of ginger against the reproductive toxicity of aluminium chloride in albino male rats

The aim of the current study was to evaluate reproductive disorders concomitant with aluminium chloride (AlCl₃) toxicity in Albino male rats. Attention was also directed to study the protective influence of ginger against this toxicity. Forty‐five mature Albino Wistar male rats were equally divided into three groups; the first group was served as control group while those of the second group (AlCl₃) were daily treated with 34 mg/kg bw. AlCl₃ orally. The third group (AlCl₃ + ginger) was treated daily with AlCl₃ as in group 2 in combination with ginger (40 mg/kg bw), which started 2 weeks prior to AlCl₃. Five animals from each group were sacrificed on days 30, 45 and 60 of treatment. AlCl₃ administration significantly decreased serum testosterone levels, increased testicular homogenate malondialdehyde and deteriorated semen picture with increased testicular DNA fragmentation. Histopathological examination revealed degenerative changes of the seminiferous tubules with focal areas of necrosed spermatogenic cells, marked degeneration and desquamation of the lining epithelial cells of epididymis as well as multiple calcified material in prostate gland following 60 days of aluminium treatment. Ginger treatment started to improve significantly all studied parameters after 60 days as compared with AlCl₃‐treated group. In the current study, it was concluded that AlCl₃ had a destructive effect on all the studied reproductive parameters. Treatment with ginger has an ameliorating effect against AlCl₃ toxicity after 60 days post‐treatment.     

Natural diversity of inflorescence architecture traces cryptic domestication genes in barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.)

Many-grained mutants occurring spontaneously among their less well-endowed field mates may have appeared to early farmers as fortunate twists of fate foreboding wealth and abundance. In domesticated barley, the number of kernel rows in spike can be tripled by recessive mutant alleles at the Six-rowed spike 1 (vrs1) locus that abolish the suppression of lateral spikelet fertility. In another barley row-type, so called intermedium-spike (int), lateral floret size is often intermediate between six-and two-rowed types. Phenotypic and sequence analyses of our intermedium-spike collection revealed that other genes can increase the size of florets and even stimulate occasional grain setting in lateral spikelets. Here, we show that a complete six-rowed phenotype occurs in a diverse panel of intermedium-spike barley carrying wildtype Vrs1 in the presence of the Int-c.a allele of the intermedium spike-c (int-c) gene, previously considered only as a modifier of lateral spikelet fertility. Int-c.a-type alleles had arisen before domestication and are associated with the enlargement of lateral florets in wild barley, suggesting that natural selection/evolution acts towards reduced lateral floret size. Since Int-c.a cannot overcome the suppression of lateral florets in the genomic background of wild barleys, we infer the existence of other gene loci, at which novel alleles or allelic combinations were selected for after domestication, to increase grain number of barley independently of Vrs1.     

How Effective is Reduced Tillage–Cover Crop Management in Reducing N2O Fluxes from Arable Crop Soils?

Field management is expected to influence nitrous oxide (N₂O) production from arable cropping systems through effects on soil physics and biology. Measurements of N₂O flux were carried out on a weekly basis from April 2008 to August 2009 for a spring sown barley crop at Oak Park Research Centre, Carlow, Ireland. The soil was a free draining sandy loam typical of the majority of cereal growing land in Ireland. The aims of this study were to investigate the suitability of combining reduced tillage and a mustard cover crop (RT?CCC) to mitigate nitrous oxide emissions from arable soils and to validate the DeNitrification?CDeComposition (DNDC) model version (v. 9.2) for estimating N₂O emissions. In addition, the model was used to simulate N₂O emissions for two sets of future climate scenarios (period 2021?C2060). Field results showed that although the daily emissions were significantly higher for RT?CCC on two occasions (p?<?0.05), no significant effect (p?>?0.05) on the cumulative N₂O flux, compared with the CT treatment, was found. DNDC was validated using N₂O data collected from this study in combination with previously collected data and shown to be suitable for estimating N₂O emissions (r ²?=?0.70), water-filled pore space (WFPS) (r ²?=?0.58) and soil temperature (r ²?=?0.87) from this field. The relative deviations of the simulated to the measured N₂O values with the 140?kg N ha^?1 fertiliser application rate were ?36?% for RT?CCC and ?19?% for CT. Root mean square error values were 0.014 and 0.007?kg N₂O?CN ha^?1 day^?1, respectively, indicating a reasonable fit. Future cumulative N₂O fluxes and total denitrification were predicted to increase under the RT?CCC management for all future climate projections, whilst predictions were inconsistent under the CT. Our study suggests that the use of RT?CCC as an alternative farm management system for spring barley, if the sole objective is to reduce N₂O emissions, may not be successful.     

Quality indices of Jew's mallow and spinach during frozen storage

In this study, Jew's mallow and spinach were heat treated and kept frozen, at –18°C, for 3 months. Analysis of some chemical components and enzymatic activities as well as a sensory evaluation were undertaken. At the end of the storage period, blanched spinach showed no PPO (polyphenyloxidase) activity at all, but still contained PO (peroxydase) and LO (lipoxygenase) activities. The untreated spinach stored under the same conditions showed high activities of PO, PPO and LO. The heat treated mallow still contained high enzyme activities which decreased slowly during frozen storage. Statistical analysis of the chemical composition and the sensory evaluation results indicated that heat treatments of mallow caused significant differences in total solids, pH, chlorophylla and total chlorophyll, while frozen storage, of samples of the same treatment for 3 months caused no significant differences in moisture, ash, oxalic acid, pH, chlorophylla and total chlorophyll. No significant differences could be noticed in the overall acceptability between mallow samples mixed with hot water and those mixed in the overall acceptability between mallow samples mixed with hot water and those mixed with a hot 0.1% MgCO₃ solution. Significant differences were found between the heat treated and the untreated mallow. Changes of the chemical composition and the overall acceptability of blanched spinach during frozen storage showed almost the same trend noticed for the Jew's mallow.