ATM is involved in cell‐cycle control through the regulation of retinoblastoma protein phosphorylation

Ataxia telangiectasia mutated protein (ATM) is a member of the phosphatidylinositol‐3 kinase (PI3K) family, which has a role in the cellular response to DNA double‐strand breaks (DSBs). In the present study, we evaluated the role of ATM in cell‐cycle control in dopaminergic rat neuroblastoma B65 cells. For this purpose, ATM activity was either inhibited pharmacologically with the specific inhibitor KU‐55933, or the ATM gene was partially silenced by transfection with small interfering RNA (siRNA). Our data indicate that although ATM inhibition did not affect the cell cycle, both treatments specifically decreased the levels of cyclin A and retinoblastoma protein (pRb), phosphorylated at Ser780. Furthermore, ATM inhibition decreased the active form of p53, which is phosphorylated at Ser15, and also decreased Bax and p21 expression. Using H₂O₂ as a positive control of DSBs, caused a rapid pRb phosphorylation, this was prevented by KU‐55933 and siRNA treatment. Collectively, our data demonstrate how a new molecular network on ATM regulates the cell cycle through the control of pRb phosphorylation. These findings support a new target of ATM. J. Cell. Biochem. 110: 210–218, 2010. © 2010 Wiley‐Liss, Inc.     

Chromosome Numbers in Three Asteraceae Tribes from Inner Mongolia (China), with Genome Size Data for Cardueae

Chromosome counts are reported for 15 species of the family Asteraceae from Inner Mongolia (People’s Republic of China). This study includes representatives of the tribes Anthemideae (Artemisia, Chrysanthemum, Filifolium, Hippolytia and Neopallasia), Astereae (Heteropappus) and Cardueae (Echinops and Olgaea). The significance of the chromosome counts is discussed for each species. Within the Anthemideae, chromosome counts for Hippolytia alashanensis (2n?=?36) and the tetraploid level of Artemisia eriopoda (2n?=?36) are reported for the first time. The chromosome number of Heteropappus altaicus (Astereae) agrees with previous reports of one (4x) of the two ploidy levels reported for this taxon. As a complement to the karyological data, genome size of the Cardueae representatives was assessed using flow cytometry. Within this tribe, Echinops gmelini (2n?=?26) and its sister taxon E. acantholepis (2n?=?14) show strongly divergent karyological patterns of difficult interpretation, whereas the count of E. przewalskyi (2n?=?32), assigned here for the first time, coincides with those of its close relatives. In Olgaea tangutica, the chromosome count (2n?=?24) and genome size (2C?=?3.01 pg) given here are the first reports for both the species and the genus.     

Erratum to “Random models of Menzerath–Altmann law in genomes” (BioSystems 107(3) (2012) 167–173)

Here we improve the mathematical arguments of Baixeries et al (BioSystems 107(3) (2012) 167–173). The corrections do not alter the conclusion that the random breakage model yields an insufficient fit to the scaling of mean chromosome length as a function of chromosome number in real genomes.     

Incorporating pressure–volume traits into the leaf economics spectrum

In recent years, attempts have been made in linking pressure–volume parameters and the leaf economics spectrum to expand our knowledge of the interrelationships among leaf traits. We provide theoretical and empirical evidence for the coordination of the turgor loss point and associated traits with net CO₂ assimilation (A_n) and leaf mass per area (LMA). We measured gas exchange, pressure–volume curves and leaf structure in 45 ferns and angiosperms, and explored the anatomical and chemical basis of the key traits. We propose that the coordination observed between mass-based A_n, capacitance and the turgor loss point (π_tlp) emerges from their shared link with leaf density (one of the components of LMA) and, specially, leaf saturated water content (LSWC), which in turn relates to cell size and nitrogen and carbon content. Thus, considering the components of LMA and LSWC in ecophysiological studies can provide a broader perspective on leaf structure and function.     

The Amaryllidaceae alkaloids: an untapped source of acetylcholinesterase inhibitors

Phytochemistry Reviews - The AChE inhibitory activity of alkaloid extracts and compounds has been in the focus of research on the plants of Amaryllidoideae subfamily since the approval of...