BackgroundNotch may behave as an oncogene or a tumor suppressor gene in lung cancer cells. Notch receptor undergoes cleavage by enzymes, including γ-secretase, generating the active Notch intracellular domain (NICD). The aim of the present study was to investigate the effect of DAPT, a γ-secretase inhibitor, in non-small cell lung cancer (NSCLC) cells, as well as the impact of epidermal growth factor (EGF) that is over-expressed by NSCLC cells, on Notch signaling. H23, A549, H661 and HCC827 human NSCLC cell lines were used, expressing various NICD and EGF receptor (EGFR) protein levels.ResultsDAPT decreased the number of H661 cells in a concentration-dependent manner, while it had a small effect on H23 and A549 cells and no effect on HCC827 cells that carry mutated EGFR. Notch inhibition did not affect the stimulatory effect of EGF on cell proliferation, while EGF prevented DAPT-induced NICD decrease in H23 and H661 cells. The type of cell death induced by DAPT seems to depend on the cell type.ConclusionsOur data indicate that inhibition of Notch cleavage may not affect cell number in the presence of EGFR mutations and that EGFR may affect Notch signalling suggesting that a dual inhibition of these pathways might be promising in NSCLC.Electronic supplementary materialThe online version of this article (doi:10.1186/s12929-015-0196-1) contains supplementary material, which is available to authorized users.

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Aim of study: To assess the role of polyphenol oxidase (PPO), peroxidase (POD) and indole-3-acetic acid oxidase (IAAox) during adventitious rooting (Ar) in semi-hardwood cuttings of the easy-to-root olive cv. ‘Arbequina’ and the difficult-to-root cv. ‘Kalamata’. Simultaneously, a histological study was carried out in both cultivars to investigate the tissue related with Ar development.Area of study: The rooting experiments were carried out in ‘Kostelenos’ nurseries (Troizinia, Greece) and in Agricultural University of Athens.Material and methods: Plant material to set up the experiment was collected from current year shoots from 15-year-old mother plants of ‘Arbequina’ and ‘Kalamata’ at three different seasons (summer, autumn and spring). The auxin indole-3-butyric acid (IBA) at 2000 mg L-1 was used as rooting inducer.Main results: Analysis revealed that ‘Kalamata’ had significantly higher enzymatic activities before experiment onset and during Ar compared to ‘Arbequina’. Control cuttings of both cultivars exhibited increased enzymatic activities compared to IBA treated ones. IAAox was on average three times higher in ‘Kalamata’ than in ‘Arbequina’ and exhibited significant peaks during Ar. Similar peaks of POD and PPO activities were also detected. Histological analyses in ‘Kalamata’ revealed a continuous sheath of sclerenchyma ring and increased cortex thickness. Significant cell proliferation occurred in the phloem region in ‘Arbequina’ 15 days after planting and afterwards the root initials started developing in the secondary phloem from cambial cells.Research highlights: The differences in enzymatic activities as well as in stem anatomy could partly justify the different rooting ability of both cultivars.

An in situ localization method for Peach latent mosaic viroid (PLMVd) that is highly sensitive, has low background signal, has a short specimen processing time and is simple and inexpensive compared to other similar methods, is described. The method is based on SYBR Green reverse transcription-polymerase chain reaction (RT-PCR) amplification of pepsin, DNase I pre-treated and FAA-fixed peach leaf sections. The leaves used were derived from healthy and PLMVd infected peach plants, including a plant infected by a Peach Calico variant of the viroid. All steps of the assay, except for the signal detection, were carried out in liquid phase in 0AE2 mL PCR tubes instead of on microscope slides, as usually used. Epifluorescence microscopy to detect PLMVd or rbcL (the positive control gene) amplified products revealed a bright signal in the leaf part corresponding to the palisade parenchyma, with sub-cellular localization of the signals in the chloroplasts, the organelles where PLMVd is known to replicate and accumulate. Although the method proved to be effective for the green peach PLMVd infected tissues, a yellow-green background fluorescent signal, sometimes more intense due to overexposure, was observed, presumably due to chlorophyll auto-fluorescence. In contrast, no auto-fluorescence signal was observed in the calico infected albino tissues. This is the first report of using liquid phase in situ RT-PCR for the cellular localization of a plant pathogen.

2 The susceptibility of eleven Prunus rootstocks to iron (Fe) deficiency was studied in hydroponics by growing them with 20 µM Fe, 0 µM Fe or 3 µM Fe+10 mM sodium bicarbonate. Based on the intensity of leaf chlorosis, the peach-almonds PR 204/84, Stylianidis K and KID2, produced at the Pomology Institute of Naoussa (Greece), showed the same or even greater tolerance than GF 677, the Greek peach-almond Retsou x Nemaguard, the plum-almond Myrandier 617 and the peaches GF 305, IDS 37, Greek wild peach seedling the greatest susceptibility whereas the plums St. Julien GF655/2 and Myrobalan 29C intermediate. Rootstocks without Fe presented significantly lower nitrogen and Fe whereas with bicarbonate significantly lower nitrogen, phosphorus, Fe and zinc.Root ferric chelate reductase activity was significantly increased in −Fe rootstocks but negatively correlated with their tolerance; physiological and morphological changes were observed along a zone of a few centimeters length, 1-2 mm behind the root tip.