1,720,966 research outputs found
Downregulation of ethylene production and biosynthetic gene expression is associated to changes in putrescine metabolism in shoot-forming tobacco thin layers.
No full textThe effect of aminoethoxyvinylglycine (AVG), an inhibitor of 1-aminocyclopropane-1-carboxylate synthase (ACS) activity, on
ethylene emission and biosynthetic gene expression, on gene expression and/or activity of polyamine (putrescine, spermidine and spermine) biosynthetic enzymes, and on diamine oxidase (DAO, EC 1.4.3.6) activity was evaluated in tobacco (Nicotiana tabacum L. cv. Samsun) thin layers cultured on a shoot-forming medium (1 mM indol-3-acetic acid (IAA) plus 10 mM benzyladenine (BA)). Northern analyses showed that ACS and 1-aminocyclopropane-1-carboxylate oxidase (ACO) transcripts were present throughout culture with a maximum accumulation on day 7. Besides ethylene emission, AVG (0.5 mM) increasingly reduced ACS and ACO messages. The time course of labelled methionine incorporation into spermidine and spermine, which share with ethylene the common precursor S-adenosylmethionine (SAM), as well as SAM decarboxylase (SAMDC, EC 4.1.1.21) activity and gene expression, were not affected by AVG treatment. On the contrary, labelled putrescine incorporation into the higher polyamines
(spermidine and spermine) and into trichloroacetic acid (TCA)-soluble polyamine conjugates was enhanced early in culture (day 2) by the drug. Putrescine biosynthetic enzyme activities, arginine decarboxylase (ADC, EC 4.1.1.19) and ornithine decarboxylase (ODC, EC 4.1.1.17), were also increased in AVG-treated explants. Moreover, inhibition of ethylene synthesis by AVG led to a strong reduction in diamine oxidising activity, especially the one associated with a cell wall-enriched fraction. Changes in putrescine biosynthesis, oxidation and flux into higher polyamines are discussed in the light of the rejuvenating effect of AVG
Challeng test per Escherichia coli verocitotossinogeni in carni macinate:utilizzo della PCR real-time
No full textL'identificazione dei ceppi patogeni di E. coli in alimenti puo' essere effettuata sia con metodi colturali (uso di terreni cromogenici o test immunoenzimatici), sia mediante analisi molecolari. Obiettivo del lavoro è valutare l'utilizzo e comparare la sensibilità del metodo molecolare (real-time PCR) rispetto a quello immunoenzimatico
Il metilgiasmonato riduce la cauologenesi in strati sottili di Nicotiana tabacum deregolando la divisione e l'espansione cellulare e inducendo modificazioni di parete
No full textThe involvment of polyamines in phytoplasma-infected periwinkle (Catharantus roseus L.) plants
No full textDe Novo Root Formation in Tobacco Thin Layers is Affected by Inhibition of Polyamine Biosynthesis
No full textThe effect of various inhibitors of polyamine biosynthesis on free and bound polyamine accumulation and on rhizogenesis was followed in thin layers excised from the stem of Nicotiana tabacum L. cv. Samsun. Trichloroacetic acid-soluble (TCA-soluble) free, TCA-soluble bound, and TCA-insoluble bound putrescine and spermidine accumulated throughout the culture period in control explants, reaching a peak on days 15-18. All the inhibitors tested depressed the rhizogenic process, though to a different extent, while leaving most of the explants viable. DL-alpha-difluoromethylornithine plus DL-alpha-difluoromethylarginine (DFMO + DFMA), specific irreversible inhibitors of ornithine- and arginine decarboxylases, respectively, almost totally inhibited rhizogenesis and polyamine accumulation. DFMO alone allowed a certain concentration of putrescine and spermidine to accumulate and rhizogenesis to occur in 20% of the explants. Cyclohexylamine (CHA), a competitive inhibitor of spermidine synthesis, did not have a strong inhibitory effect on root formation but depleted free and bound spermidine almost totally. Methylglyoxal-bis(guanyl)hydrazone (MGBG), an inhibitor of spermidine synthesis, caused a strong reduction in rhizogenesis but an accumulation of polyamines at the end of the culture period. No noticeable reversion of the rooting inhibition was observed by supplying the drug together with the polyamine whose synthesis was inhibited. The uptake and accumulation of exogenously supplied polyamines throughout the culture period was followed. The involvement of the three classes of polyamines in rhizogenic response is discussed in relation to the effect of the inhibitors of their biosynthesis
Polyamine conjugate levels and ethylene biosynthesis: inverse relationship with vegetative bud formation in tobacco thin layers
No full text
Real-time PCR and enzyme-linked fluorescent assay methods for detecting Shiga-toxin-producing Escherichia coli in mincemeat samples
No full textThis work aimed to compare real-time polymerase chain reaction (PCR) with the commercially available enzyme-linked fluorescent assay (ELFA) VIDAS ECOLI O157 for detecting Escherichia coli O157 in mincemeat. In addition, a PCR-based survey on Shiga-toxin-producing E. coli (STEC) in mincemeat collected in Italy is presented. Real-time PCR assays targeting the stx genes and a specific STEC O157 sequence (SILO157, a small inserted locus of STEC O157) were tested for their sensitivity on spiked mincemeat samples. After overnight enrichment, the presence of STEC cells could be clearly determined in the 25 g samples containing 10 bacterial cells, while the addition of five bacteria provided equivocal PCR results with Ct values very close to or above the threshold of 40. The PCR tests proved to be more sensitive than the ELFA-VIDAS ECOLI O157, whose detection level started from 50 bacterial cells/25 g of mincemeat. The occurrence of STEC in 106 mincemeat (bovine, veal) samples collected from September to November 2004 at five different points of sale in Italy (one point of sale in Arezzo, Tuscany, central Italy, two in Mantova, Lombardy, Northern Italy, and two in Bologna, Emilia-Romagna, upper-central Italy) was less than 1%. Contamination by the main STEC O-serogroups representing a major public health concern, including O26, O91, O111, O145, and O157, was not detected. This survey indicates that STEC present in these samples are probably not associated with pathogenesis in humans
- …
