Suitable reference genes for accurate gene expression analysis in Papaver rhoeas under 2,4-D herbicide stress

Resistance to 2,4-D (2,4-diclorophenoxyacetic acid) herbicide is increasing in various dicotyledonous weed species, including Papaver rhoeas, a weed infesting Southern European wheat crops. Non-target-site resistance to this herbicide is governed by a range of genes involved in herbicide stress response. To enable reliable measurement of gene expression levels in herbicide-resistant and susceptible plants it is necessary to normalize qPCR data using internal control genes with stable expression. In an attempt to find the best reference genes, the stability of seven candidate reference genes was assessed in plants resistant and susceptible to 2,4-D, subjected or not to herbicide stress. Using three statistical algorithms (geNorm, BestKeeper and NormFinder), the overall results revealed that glyceraldehyde-3-phosphate dehydrogenase, actin and ubiquitin were the most stable reference genes. The normalization expression levels of GH3 (indole-3-acetic acid amido synthetase) and GST3 (glutathione S-transferase) which are two genes up-regulated following 2,4-D treatment, were determined to verify the stability of these selected reference genes. A sudden increase in GH3 and GST3 expression was already detected 5h after herbicide application, confirming their involvement in plant response to 2,4-D. The validation results confirmed the applicability and accuracy of these reference genes. This study identified and validated reference genes in the non-model weed species P. rhoeas and these will facilitate gene expression analysis studies aimed at identifying functional genes associated with non-target-site resistance.

Plerixafor (P) plus G-CSF (G) in previous peripheral blood progenitor cell (HPC) mobilization failures (MF)

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Background: Successful autologous stem cell transplantation (AT) requires harvesting sufficient HPC to ensure reliable engraftment, which cannot be accomplished in ∼10% of previously treated patients. Methods: MF was defined as the inability to collect at least 2 x106 CD34+ cells/kg with growth factor alone (GF) (n=38) or in combination with chemotherapy (GF-CT) (n=27). Of 65 patients reported here, 45 were enrolled in a compassionate use program and 20 were part of a clinical trial (AMD3100–2102); 55 had MM, 9 had lymphoma and 1 had primary amyloidosis. All patients had been treated previously and included prior AT in 26 patients, 15 of whom had 2 AT and 2 had ≥3 AT. The P+G regimen started with G (10 μg/kg) for 4 days, P (240 μg/kg) was added on the evening of day 4; both P and G were continued until completion of collection. In the case of MM, all collected products were analyzed for tumor contamination by DNA/cIg flow cytometry. Results: Of all 65 patients, 63 initiated apheresis which yielded a median 3.6x106 CD34/ kg (range, 0.3–17.8) during a median of 5 days (d) of collection (range, 2–7), with successive median daily CD34 yields of 1.1, 0.9, 0.6, 0.5, 0.3, 0.4 and 0.5 x106/kg. MM cells were mobilized in only 2/55 patients. Additional collection was undertaken in 25 patients, using GF or GF-CT in 19 (median, 3.2x106 CD34 cells; range, 0–8.5), further P+G in 5 (median, 1.7x106 CD34 cells/kg; range, 0.9–3.5), and 1 patient received P+G on a third occasion (2.2x106 CD34 cells /kg). Of 63 patients, 51 (81%) and 24 (38%), respectively, collected ≥2.0 and ≥5.0x106 CD34 /kg. AT was supported with P+G derived products in 43 patients including 7 who received 2 AT. With median infused CD34+cells of 3.6x106 / kg (range, 1.0–7.7), the median times to neutrophils > 500/μl and platelets >20,000/ μl were 14 d (range, 11–35) and 15 d (range, 9–253). Conclusions: P+G ensures collection of an adequate HPC product after MF in 81% that affords durable engraftment even though 40% had prior AT.

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