Menus for Feeding Black Holes

Black holes are the ultimate prisons of the Universe, regions of spacetime where the enormous gravity prohibits matter or even light to escape to infinity. Yet, matter falling toward the black holes may shine spectacularly, generating the strongest source of radiation. These sources provide us with astrophysical laboratories of extreme physical conditions that cannot be realized on Earth. This chapter offers a review of the basic menus for feeding matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher

The genes encoding for enzymes of polyamine biosynthesis and catabolism are developmentally regulated in Vitis vinifera L. and linked to abiotic stress response

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: Cost858 Congress on Functional Gene and Analysis in Grapevin

Physiological and molecular responses of grapevine to salinity/drought

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: Congress on Aquaporin

New molecular strategies for tolerance of plants to salinity

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: 15th FESPB Congres

Abiotic stress generated ROS signal expression of anionic glutamate dehydrogenases to form glutamate for proline synthesis

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: Plant Cell 1

The subcutaneous ICD as an alternative to the conventional ICD system: Initial experience in Greece and a review of the literature

The introduction of an implantable cardioverter defibrillator (ICD) in clinical practice has revolutionized our therapeutic approach for both primary and secondary prevention of sudden cardiac death (SCD), as it has proven to be superior to medical therapy in treating potentially life-threatening ventricular arrhythmias and has resulted in reduced mortality rates. However, implantation of a conventional ICD carries a non-negligible risk of periprocedural and long-term complications associated with the transvenous ICD leads. The entirely subcutaneous implantable cardioverter defibrillator (S-ICD) has recently emerged as a therapeutic alternative to the conventional ICD for patients with various cardiopathies and who are at high risk of SCD. The main advantage is the avoidance of vascular access and thus avoidance of complications associated with transvenous leads. Patients without pacing indications, such as bradycardia, a need for antitachycardia pacing or cardiac resynchronization, as well as those at higher risk of complications from transvenous lead implantation are perfect candidates for this novel technology. The subcutaneous ICD has proven to be equally safe and effective compared to transvenous ICD systems in early clinical trials. Further technical improvements of the system will likely lead to the expansion of indications and widespread use of this technology. In the present review, we discuss the indications for this system, summarize early clinical experiences and highlight the advantages and disadvantages of this novel technology. In addition, we present the first two cases of subcutaneous cardioverter defibrillator system implantation in Greece. © 2017 Hellenic Society of Cardiology

What is new about glutamate dehydrogenase?

Μη διαθέσιμη περίληψηNot available summarizationΠαρουσιάστηκε στο: Nitrogen 200

Nitrogen flow into regulatory molecules: The case of Polyamines and Polyamine oxidases.

""\\"Glutamate plays a central role in the flow of nitrogen to various regulatory molecules, such as Polyamines (PAs). PAs are low MW nitrogenous molecules. The most common PAs are the diamine Putrescine (Put), the triamine Spermidine (Spd) and the tetramine Spermine (Spm). In plants, Put and Spd are the obligatory precursors of Spd and Spm, respectively. PAs have been implicated in plant growth and development, abiotic and biotic stress responses (1,2,3,4,5,6). PA oxidation is catalyzed by Di- and PA oxidases (DAO and PAOs, respectively) in the apoplast [terminal catabolism; (3)],or in the cytoplasm and the peroxisomes [PA back-conversion; (4)]. In both cases, H2O2 is generated. Recently, PA catabolism-derived H2O2 was shown to significantly participate in the physiological functions of PAs. Stress induces PA exodus into the apoplast, where it is oxidized by apoplastic PAO leading to increase of H2O2 load; this in turn participates in signalling events, inducing differential gene expression, which results to either PA homeostatic responses or the execution of programmed cell death [PCD; (4,6)]. Thus, the level of apoplastic H2O2 determines whether stress-tolerant mechanisms or the PCD syndrome will be induced. Engineering the PA catabolic pathway led to increased tolerance to biotic but sensitivity to abiotic stress (5,6). The pathway is partially controlled by the phytohormone abscissic acid (ABA), which is involved in stress-dependent signalling cascades, including those controlling stomatal closure (7). ABA induces expression of AtPAO3, a peroxisomal Arabidopsis PAO and GUS reporter analysis, revealed that cis-regulatory elements in the promoter region control this induction (8,9). Interestingly, GUS activity post-treatment with ABA was specifically localized to guard cells, implying a direct role of PAO-derived H2O2 in stomatal closure. Moreover, the complete identification and analysis of AtPAOs in Arabidopsis revealed that all four PAOs (AtPAO1, AtPAO2, AtPAO3 and AtPAO4) are back-converting Spm to Spd and additionally AtPAO2 and AtPAO3 back-convert Spd to Put (8,9). Thus, Arabidopsis seems to lack PAOs involved in terminal catabolism of PAs in contrast to maize, in which the until now characterized PAOs produce 1,3-diaminopropane and 4-aminobutanal or N-(3-aminopropyl)-4-aminobutanal from Spd or Spm oxidation, respectively. H1-NMR studies revealed that AtPAOs, in addition to H2O2 and Spd or Put, produce 3-aminopropanal, which can be further converted to the osmoprotectant molecule β-alanine and pantothenate in a pairwise reaction. The AtPAOs are differentially expressed, as revealed by GUS reporter assays, implying functional diversity inside the AtPAOs family (8,9). Furthermore, Spd Oxidase-derived H2O2 regulates pollen plasma membrane hyperpolarization-activated Ca2+-permeable channels, pollen tube growth and number of seeds (10). Also, PAO-derived H2O2 acts as a signal for deposition of secondary wall and as a mediator of developmental PCD in plant tissues resulting to suppressed primary maize root elongation by inhibiting cell growth and altering cell cycle progression (11). To sum up, all these results along with the recent finding of the involvement of AtPAOs in catabolism of thermospermine, a Spm isomer involved in vascular differentiation and stress adaptation, reveal novel aspects of the PA catabolic pathway and its genetic engineering may result to significant phenotypical and stress-tolerant genotypes. . . REFERENCES. 1.Paschalidis KA & KA Roubelakis-Angelakis (2005) Sites and regulation of polyamine catabolism in the tobacco plant. Correlations with cell division\\\\\\\/expansion, cell cycle progression, and vascular development. Plant Physiol 138(4):2174-84. 2.Paschalidis KA, PN Moschou, I Toumi & KA Roubelakis-Angelakis (2009) Polyamine anabolic\\\\\\\/catabolic regulation along the woody grapevine plant axis is linked to vascular differentiation and to stomatal closure. J Plant Physiol 166(14):1508-19. 3.Moschou, PN, ID Delis, KA Paschalidis & KA Roubelakis-Angelakis (2008) Transgenic tobacco plants overexpressing polyamine oxidase are not able to cope with oxidative burst generated by abiotic factors. Physiol Plant 133(2):140-56. 4.Moschou PN, M. Sanmartin, A. H. Andriopoulou, E. Rojo, J. J. Sanchez-Serrano & KA Roubelakis-Angelakis (2008) Bridging the gap between plant and mammalian polyamine catabolism: a novel peroxisomal polyamine oxidase responsible for a full back-conversion pathway in Arabidopsis. Plant Physiol 147(4):1845-57. 5.Moschou, PN, PF Sarris, N Scandalis, AH Andriopoulou, KA Paschalidis, NJ Panopoulos & KA Roubelakis-Angelakis (2009) Engineered polyamine catabolism preinduces tolerance of tobacco to bacteria and oomycetes. Plant Physiol 149(4):1970-81. 6.Moschou, PN, KA Paschalidis, ID Delis, AH Andriopoulou, GD Lagiotis & KA Roubelakis-Angelakis (2008) Spermidine exodus and oxidation in the apoplast induced by abiotic stress is responsible for H2O2 signatures that direct tolerance responses in tobacco. Plant Cell 20(6): 1708-24.. 7.Toumi I, PN Moschou, KA Paschalidis, S Daldoul, B Bouamama, S Chenennaoui, A Ghorbel, A Mliki & KA Roubelakis-Angelakis 2010. Abscisic acid signals reorientation of polyamine metabolism to orchestrate stress responses via the polyamine exodus pathway in grapevine. J Plant Physiol. doi:10.1016\\\\\\\/j.jplph. 2009.10.022.. 8. Fincato P, PN Moschou, V Spedatelli, R Tavazza, R Angelini, R Federico, KA Roubelakis-Angelakis & P Tavladoraki (2011) Functional diversity inside the Arabidopsis polyamine oxidase gene family. J Exp Bot 62:1155-1168 doi: 10.1093\\\\\\\/jxb\\\\\\\/erq341. 9.Fincato P, PN Moschou, A Ahou, KA Roubelakis-Angelakis, R Federico & P Tavladoraki (2011) The members of Arabidopsis thaliana PAO gene family exhibit tissue-organ specific expression pattern during seedling growth and flower development. Amino Acids DOI 10.1007\\\\\\\/s00726-011-0999-7.. 10.Wu J, H Qu, Z Shang, X Jiang, PN Moschou, KA Roubelakis-Angelakis & S Zhang (2010) Spermidine oxidase-derived H2O2 activates downstream Ca2+ channels which signal pollen tube growth in Pyrus pyrifolia. Plant J 63:1042-1053, DOI: 10.1111\\\\\\\/j.1365-313X.2010.04301.x. 11.Tisi A, R Federico, S Moreno, S Lucretti, PN Moschou, KA Roubelakis-Angelakis, R Angelini & A Cona (2011) Perturbation of polyamine catabolism can strongly affect root development and xylem differentiation. Plant Physiol. DOI:10.1104\\\\\\\/pp.111.173153.. . . \\""

Spermidine affects the transcriptome responses to high temperature stress in ripening tomato fruit* #

Objective: High temperature adversely affects quality and yield of tomato fruit. Polyamine can alleviate heat injury in plants. This study is aimed to investigate the effects of polyamine and high temperature on transcriptional profiles in ripening tomato fruit. Methods: An Affymetrix tomato microarray was used to evaluate changes in gene expression in response to exogenous spermidine (Spd, 1 mmol/L) and high temperature (33/27 °C) treatments in tomato fruits at mature green stage. Results: Of the 10 101 tomato probe sets represented on the array, 127 loci were differentially expressed in high temperature-treated fruits, compared with those under normal conditions, functionally characterized by their involvement in signal transduction, defense responses, oxidation reduction, and hormone responses. However, only 34 genes were up-regulated in Spd-treated fruits as compared with non-treated fruits, which were involved in primary metabolism, signal transduction, hormone responses, transcription factors, and stress responses. Meanwhile, 55 genes involved in energy metabolism, cell wall metabolism, and photosynthesis were down-regulated in Spd-treated fruits. Conclusions: Our results demonstrated that Spd might play an important role in regulation of tomato fruit response to high temperature during ripening stage