Peroxidases during adventitious rooting in cuttings of <Emphasis Type="Italic">Arbutus unedo</Emphasis> and <Emphasis Type="Italic">Taxus baccata</Emphasis> as affected by plant genotype and growth regulator treatment

Cuttings of Arbutus unedo (strawberry tree) and Taxus baccata (yew) were treated with 8.0 and 10.0 g l^–1, respectively, of KIBA, IBA, IAA, NAA and Paclobutrazol. No rooting occurred without growth regulator treatment. The effect of growth regulators on percentage of rooting followed the order KIBA > IBA > IAA = NAA = Paclobutrazol = 0% (for A. unedo) and KIBA > IBA > IAA > NAA > Paclobutrazol = 0% (for T. baccata). Genotypes of the above plant species had significant effects on the number and length of roots, percentage of rooting and peroxidase specific activity (PA) on KIBA-treated cuttings. High PA seems to be related with low percentage of rooting in the case of A. unedo cuttings while no similar results were noticed in the case of T. baccata. Electrophoretic analysis revealed the appearance of two to three anionic and one cationic peroxidase isoforms in A. unedo cuttings, while six to nine anionic and no cationic peroxidases isoforms appeared in the case of T. baccata genotypes. During adventitious rooting, the PA showed the three interdependent phases (induction, initiation, expression) in both K-IBA treated cuttings of A. unedo and T. baccata, but in a different time course.     

The roles of p27Kip1 and DNA damage signalling in the chemotherapy‐induced delayed cell cycle checkpoint

DNA lesions trigger the DNA damage response (DDR) machinery, which protects genomic integrity and sustains cellular survival. Increasing data underline the significance of the integrity of the DDR pathway in chemotherapy response. According to a recent work, persistent exposure of A549 lung carcinoma cells to doxorubicin induces an initial DDR‐dependent checkpoint response, followed by a later DDR‐independent, but p27^Kip1‐dependent one. Prompted by the above report and to better understand the involvement of the DDR signaling after chemotherapeutic stress, we examined the potential role of the canonical DDR pathway in A549 cells treated with doxorubicin. Exposure of A549 cells, prior to doxorubicin treatment, to ATM, ATR and DNA‐PKcs inhibitors either alone or in various combinations, revealed that the earlier documented two‐step response was DDR‐dependent in both steps. Notably, inhibition of both ATM and ATR or selective inhibition of ATM or DNA‐PKcs resulted in cell‐cycle re‐entry despite the increased levels of p27^Kip1 at all time points analyzed. We further investigated the regulation of p27^Kip1 protein levels in the particular setting. Our results showed that the protein status of p27^Kip1 is mainly determined by p38‐MAPK, whereas the role of SKP2 is less significant in the doxoroubicin‐treated A549 cells. Cumulatively, we provide evidence that the DNA damage signaling is responsible for the prolonged cell cycle arrest observed after persistent chemotherapy‐induced genotoxic stress. In conclusion, precise identification of the molecular mechanisms that are activated during the chemotherapeutic cycles could potentially increase the sensitization to the therapy applied.     

Leptophytum flavescens comb. nov. (Corallinales,Rhodophyta), an Arctic endemic from the sublittoral of NW Spitsbergen,North Norway,and western Novaya Zemlya,with epitypification of L. laeve

Type material of Lithothamnion flavescens Kjellman, originally described from Karlsøy (Troms) and Karmakul Bay (Novaya Zemlya), is re-examined and a lectotype is selected. Type specimens and other collections from NW Spitsbergen and North Norway possess distinctive characters of the genus Leptophytum, including the development of flattened epithallial cells, short subepithallial cells, and simple spermatangial structures. Leptophytum flavescens (Kjellman) comb. nov. resembles the generitype Leptophytum laeve, differing in having: (1) a thicker perithallium, to 900?µm (vs. 350?µm in L. laeve), that embeds older conceptacles, and (2) non-differentiated (in size or shape) pore cells of multiporate roofs. An epitype for L. laeve is also selected, which consolidates the status of this species and the genus, in agreement with the current literature and all publications prior to 1996.     

Serum Gc system in liver cirrhosis and hepatoma

Summary Serum Gc polymorphism was studied in 85 patients with liver cirrhosis, in 65 with cirrhosis plus hepatoma, and in 40 with hepatoma without cirrhosis. Six hundred unrelated healthy Greeks served as controls. The Gc 1-1 phenotype was found more frequently in patients who had cirrhosis with or without hepatoma but the incidence of the Gc¹ gene was significantly higher in patients with cryptogenic-HBsAg negative cirrhosis. On the other hand, the Gc 2-2 phenotype was found about three times more frequently in patients who had hepatoma without cirrhosis, and the incidence of the Gc² gene was significantly higher in the same group than in the controls. Consequently, it could be surmised that the Gc¹ and the Gc² genes predispose, under the influence of various factors, the development of cryptogenic cirrhosis and hepatoma without cirrhosis, respectively.     

Novel selective inhibitors of aminopeptidases that generate antigenic peptides

Endoplasmic reticulum aminopeptidases, ERAP1 and ERAP2, as well as Insulin regulated aminopeptidase (IRAP) play key roles in antigen processing, and have recently emerged as biologically important targets for manipulation of antigen presentation. Taking advantage of the available structural and substrate-selectivity data for these enzymes, we have rationally designed a new series of inhibitors that display low micromolar activity. The selectivity profile for these three highly homologous aminopeptidases provides a promising avenue for modulating intracellular antigen processing.