O tratamento de pré-emergência com o 2, 4-D no milho

In order to study the action of herbicides - sodium salt, amine salt and ester of 2,4-D, TCA and 2,4,5-T a preliminary experiment for pre-emergence weed control was corried out, and the corresponding results are given in table I and II. The corn used in the experiments was of the flint type 1A 3531. The loam soil on which the experiment has been carried out is called "terra roxa". All treatments were highly significant when compared with the check plots, except the 2B one in the control of broad leaf weeds, and 4B in the control of grass weeds. Among these treatments there are no significant differences. But we note the following: (table I). a) treatments of higher concentrations were superior to lower ones. b) the treatments which gave the best control for broad leaf weeds were in the following decreasing order: 1A, 5A and 3A. For grass weeds, they were 5A, 1A and 3A. c) the amine 2,4-D (600 grs. per hectare) supplied very good control when we get into consideration that on the acid basis, it was in very low concentration. d) TCA in high concentration affected the germination, growth and yield, in the lower one it did not show good control of weeds, especially of grasses. It is not suitable for pre-emergence control in corn. e) 2,4,5-T was not better than the 2,4-D products. As it is much more expensive than the others, economically its use in pre-emergence weed control in corn is not praticable. f) all the products used controled grass weeds as well as broad leaf ones; this show the superiority of the pre-emergence treatment method over that of post-emergence. g) Even a dose as strong as the treatment 1A (3.400g. of 2,4-D acid per hectare) did not damage corn production (table II). h) the superiority noted in the production of all the treatments with the exception of 2A, which damaged the plants, we atribute to the lack of competion between corn and weeds; all chek-plots suffered this competition, because they were not Probably, there was, also, hormonial effect of 2,4-D on the corn plant. Not withstanding the fact that the present experiment has been successful, we think that new researches are necessary, especially with the purpose of studying factors as climate and soil which in other countries, interferred with the success of the pre-emergence weed control.

Efeito do ácido 2,4-diclorofenoxiacético (2,4-D) na absorção do fósforo (32p) pelo trigo (Triticum aestivum., L) e a sua distribuição na planta

O objetivo deste trabalho foi estudar o efeito de diferentes concentrações de 2,4-D na absorção de fósforo - pelo trigo (Triticum aestivum, L) no estado de 3 folhas e a sua distribuição na planta. Foram realizados quatro ensaios em vaso, conduzidos em casa de vegetação, com quatro repetições. As plantas foram cortadas 8 horas, 26 e 50 horas após a pulverização do herbicida. Em cada um dos ensaios foram aplicados 4 doses de 2,4-D: 0, 1000, 2000 e 4000 ppm e uma solução contendo 32p. Os dados obtidos mostraram que: - 0, 2,4-D afetou a absorção do fósforo e a distribuição deste na planta. - A tendência, nos quatro ensaios, foi de que as doses utilizadas estimularam a absorção do fósforo pelo trigo, a qual foi decrescendo com o decorrer do tempo. - A distribuição do fósforo foi, de modo geral, estimulada, decrescendo com o decorrer do tempo. No terceiro ensaio, quando as plantas foram pulverizadas com 2000 e 4000 ppm. de 24-D, a distribuição foi prejudicada, sendo maior naquelas plantas não tratadas com o herbicida.

Diseño y fabricación de una antena con diversidad en polarización para redes WIFI a 2,4 GHz

Existeixen diferents tecnologies de transmissió sense fils, però la més coneguda és la tecnologia WIFI (Wireless Fidelity) que opera a la banda dels 2,4 GHz a Europa. Aquest tipus de xarxes opera en entorns indoor, on el canal està sotmès a una aleatorietat i complexitat elevades degut a la presència d’una gran quantitat d’elements que poden fer que la senyal rebuda presenti variacions importants en les seves característiques (nivell de senyal, polarització...). Aquest fet motiva la necessitat de desenvolupar i implantar sistemes de comunicacions amb solucions per poder minimitzar els efectes provocats per l’entorn a la senyal. Per poder pal·liar aquestes variacions, en aquest projecte s’ha dissenyat i fabricat una antena formada per dos dipols disposats un ortogonal a l’altre de manera que existeixi diversitat en polarització. La freqüència de treball de la antena és de 2,4 GHz. Rebuda una senyal de RF, el circuit de commutació permetrà seleccionar el dipol pel qual es rep la senyal de RF amb una major potència.

Paul et la Loi : le retournement (Philippiens 3,2-4,1)

(Résumé de l'ouvrage) L'apôtre Paul est au centre d'une intense interrogation aujourd'hui. Quel fut son rapport au judaïsme ? Que sait-il de Jésus ? Comment s'est construite sa théologie, d'une épître à l'autre ? Dix-huit biblistes suisses, français, italiens, allemands et américains ont été invités à explorer la question. Leurs analyses sont précises, rigoureuses et documentées. On trouvera ici une synthèse unique en français des plus récentes avancées de la recherche paulinienne.

More about the role of 2,6-dichlorophenol in tick courtship: identification and olfactometer bioassay in Amblyomma cajennense and Rhipicephalus sanguineus

This study aimed to identify 2,6-dichlorophenol (2,6-DCP) in Amblyomma cajennense and to evaluate its role in A. cajennense and Rhipicephalus sanguineus courtship. Hexanic extract from attractive females was purified by solid phase extraction and the phenol was identified by the single ion monitoring method using GC/MS. In an olfactometer, the responses of A. cajennense and R. sanguineus males to females, control rubber septa or rubber septa impregnated with 2,6-DCP at 50, 500, and 5000 ng, respectively, were studied. 2,6-DCP was identified in A. cajennense extract and the males oriented themselves toward the concentration of 500 ng. These septa and the females were recognized as copula partners. The septa treated with 2,6-DCP did not attract and were not even recognized by the R. sanguineus males, whereas the females were recognized. Due to the presence of 2,6-DCP in A. cajennense and the results of biological bioassays, it was concluded that this compound acts as an attractant and mounting sex pheromone in this tick, but it does not play any role in R. sanguineus courtship.

Species differences in the response of liver drug-metabolizing enzymes to (S)-4-O-tolylsulfanyl-2-(4-trifluormethyl-phenoxy)-butyric acid (EMD 392949) in vivo and in vitro.

Induction of drug-metabolizing enzymes (DMEs) is highly species-specific and can lead to drug-drug interaction and toxicities. In this series of studies we tested the species specificity of the antidiabetic drug development candidate and mixed peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist (S)-4-O-tolylsulfanyl-2-(4-trifluormethyl-phenoxy)-butyric acid (EMD 392949, EMD) with regard to the induction of gene expression and activities of DMEs, their regulators, and typical PPAR target genes. EMD clearly induced PPARalpha target genes in rats in vivo and in rat hepatocytes but lacked significant induction of DMEs, except for cytochrome P450 (P450) 4A. CYP2C and CYP3A were consistently induced in livers of EMD-treated monkeys. Interestingly, classic rodent peroxisomal proliferation markers were induced in monkeys after 17 weeks but not after a 4-week treatment, a fact also observed in human hepatocytes after 72 h but not 24 h of EMD treatment. In human hepatocyte cultures, EMD showed similar gene expression profiles and induction of P450 activities as in monkeys, indicating that the monkey is predictive for human P450 induction by EMD. In addition, EMD induced a similar gene expression pattern as the PPARalpha agonist fenofibrate in primary rat and human hepatocyte cultures. In conclusion, these data showed an excellent correlation of in vivo data on DME gene expression and activity levels with results generated in hepatocyte monolayer cultures, enabling a solid estimation of human P450 induction. This study also clearly highlighted major differences between primates and rodents in the regulation of major inducible P450s, with evidence of CYP3A and CYP2C inducibility by PPARalpha agonists in monkeys and humans.

Gm(1,2,4,10,21) and Km(1) factors in vitreous humor.

The presence of Gm(1,2,4,10,21) and Km(1) factors in vitreous humor taken from human corpses was investigated. The results revealed a good agreement between the factors detected in this biological material and in blood. Their presence in vitreous humor is independent of the secretor type.

Is the ability of biocontrol fluorescent pseudomonads to produce the antifungal metabolite 2,4-diacetylphloroglucinol really synonymous with higher plant protection?

The antifungal compound 2,4-diacetylphloroglucinol (Phl) contributes to biocontrol in pseudomonads, but whether or not Phl(+) biocontrol pseudomonads display higher plant-protecting activity than Phl(-) biocontrol pseudomonads remains to be demonstrated. This issue was addressed by assessing 230 biocontrol fluorescent pseudomonads selected from a collection of 3132 bacterial isolates obtained from 63 soils worldwide. One-third of the biocontrol pseudomonads were Phl(+) and almost all Phl(+) isolates also produced hydrogen cyanide (HCN). The only Phl(+) HCN(-) strain did harbor hcn genes, but with the deletion of a 134 bp hcnC fragment corresponding to an ADP-binding motif. Statistical analysis of biocontrol isolate distributions indicated that Phl production ability was associated with superior disease suppression activity in the Pythium-cucumber and Fusarium-tomato pathosystems, but this was also the case with HCN production ability. However, HCN significance was not as strong, as indicated both by the comparison of Phl(-) HCN(+) and Phl(-) HCN(-) strains and by correlation analyses. This is the first population-level demonstration of the higher plant-protecting activity of Phl(+) biocontrol pseudomonads in comparison with Phl(-) biocontrol pseudomonads.

Megazol and its bioisostere 4H-1,2,4-triazole: comparing the trypanocidal, cytotoxic and genotoxic activities and their in vitro and in silico interactions with the Trypanosoma brucei nitroreductase enzyme

Megazol (7) is a 5-nitroimidazole that is highly active against Trypanosoma cruzi and Trypanosoma brucei, as well as drug-resistant forms of trypanosomiasis. Compound 7 is not used clinically due to its mutagenic and genotoxic properties, but has been largely used as a lead compound. Here, we compared the activity of 7 with its 4H-1,2,4-triazole bioisostere (8) in bloodstream forms of T. brucei and T. cruzi and evaluated their activation by T. brucei type I nitroreductase (TbNTR) enzyme. We also analysed the cytotoxic and genotoxic effects of these compounds in whole human blood using Comet and fluorescein diacetate/ethidium bromide assays. Although the only difference between 7 and 8 is the substitution of sulphur (in the thiadiazole in 7) for nitrogen (in the triazole in 8), the results indicated that 8 had poorer antiparasitic activity than 7 and was not genotoxic, whereas 7 presented this effect. The determination of Vmax indicated that although 8 was metabolised more rapidly than 7, it bounds to the TbNTR with better affinity, resulting in equivalent kcat/KM values. Docking assays of 7 and 8 performed within the active site of a homology model of the TbNTR indicating that 8 had greater affinity than 7.

3-amino-1,2,4-triazole inhibits macrophage NO synthase.

Murine macrophages activated by interferon-gamma and lipopolysaccharide become leishmanicidal through a process involving L-arginine-derived nitrogen oxidation products. Both nitrite secretion and parasite killing by activated macrophages were inhibited by 3-amino-1,2,4-triazole as well as the related compound, 3-amino-1,2,4-triazine. Moreover, NO synthase activity in cytosolic extracts of activated cells was inhibited by both compounds. 4-amino-1,2,4-triazole, an isomer of 3-amino-1,2,4-triazole, was without effect. Our results suggest that besides its known inhibitory effect on catalases and peroxidases, 3-amino-1,2,4-triazole is an inhibitor of NO synthase. The resemblance between the tautomeric form of 3-amino-1,2,4-triazole and the guanidino group of L-arginine, the natural substrate for NO synthase, might be responsible for the observed inhibition.

Biotic Factors Affecting Expression of the 2,4-Diacetylphloroglucinol Biosynthesis Gene phlA in Pseudomonas fluorescens Biocontrol Strain CHA0 in the Rhizosphere.

ABSTRACT Production of the polyketide antimicrobial metabolite 2,4-diacetyl-phloroglucinol (DAPG) is a key factor in the biocontrol activity of Pseudomonas fluorescens CHA0. Strain CHA0 carrying a translational phlA'-'lacZ fusion was used to monitor expression of the phl biosynthetic genes in vitro and in the rhizosphere. Expression of the reporter gene accurately reflected actual production of DAPG in vitro and in planta as determined by direct extraction of the antimicrobial compound. In a gnotobiotic system containing a clay and sand-based artificial soil, reporter gene expression was significantly greater in the rhizospheres of two monocots (maize and wheat) compared with gene expression in the rhizospheres of two dicots (bean and cucumber). We observed this host genotype effect on bacterial gene expression also at the level of cultivars. Significant differences were found among six additional maize cultivars tested under gnotobiotic conditions. There was no difference between transgenic maize expressing the Bacillus thuringiensis insecticidal gene cry1Ab and the near-isogenic parent line. Plant age had a significant impact on gene expression. Using maize as a model, expression of the phlA'-'lacZ reporter gene peaked at 24 h after planting of pregerminated seedlings, and dropped to a fourth of that value within 48 h, remaining at that level throughout 22 days of plant growth. Root infection by Pythium ultimum stimulated bacterial gene expression on both cucumber and maize, and this was independent of differences in rhizosphere colonization on these host plants. To our knowledge, this is the first comprehensive evaluation of how biotic factors that commonly confront bacterial inoculants in agricultural systems (host genotype, host age, and pathogen infection) modulate the expression of key biocontrol genes for disease suppression.