Aluminum ions inhibit phospholipase D in a microtubule-dependent manner.

Aluminum is a highly cytotoxic metal to plants, but the molecular base and the primary target of Al toxicity are still unknown. The most important physiological consequence of Al toxicity is a cessation of root growth and changes in root morphology suggesting a role of the root cytoskeleton as a target structure. The important role of phospholipid degrading enzyme phospholipase D in regulation of cytoskeleton remodelling in both animal and plant organisms is now evident. Both the phospholipid pathway and the cytoskeleton are influenced by Al(3+), but their relationship with Al stress remains to be explored. Therefore, we tested the possibility that Al stress could be sensed by plants through microtubules in close interaction with phospholipases. We have shown that Al(3+) reduced the formation of phosphatidic acid in vivo, inhibited activity of phosphatidylinositol-4,5-bisphosphate-dependent phospholipase D in vitro and that the phosphatidic acid production is modified by microtubule dynamics.     

Micropropagation and salt tolerance of in vitro grown Crithmum maritimum L.

Crithmum maritimum (Apiaceae), a perennial halophyte native in Greece, could be used as an alternative culture at problematic soils. It presents significant economical potentials as its essential oils are in high demand from the medicinal and cosmetic industry. The response of the species on in vitro conditions was studied. MS proved to be the most effective of the basal media tested for in vitro adventitious shoot production, resulting in significantly increased number of new microshoots/explant and higher shoots. 6-Benzyladenine (BA) at 2.5 μM increased shoot proliferation. The combination of α-Naphthaleneacetic acid (NAA) (1–2.5 μM) with BA (2.5 μM) had a positive influence at simultaneous proliferation and rooting resulting in high rooting percentage (82.5–95%) and increased number of roots. Rooting percentage reached 100% and number of roots increased significantly when 0.5 μM and 1 μM IBA was combined with ½MS and full strength MS. The in vitro response to salinity stress (0–300 mM NaCl) was also tested. Shoot proliferation was gradually reduced at higher concentrations of NaCl but shoot height was enhanced. Acclimatization procedure was successful.     

Assessment of apoptosis by immunohistochemical markers compared to cellular morphology in ex vivo-stressed colonic mucosa.

Apoptosis competence is central to the prevention of cancer. Frequency of apoptotic cells, after a sample of colonic tissue is stressed, can be used to gauge apoptosis competence and, thus, possible susceptibility to colon cancer. The gold standard for assessment of apoptosis is morphological evaluation, but this requires an experienced microscopist. Easier-to-use immunohistochemical markers of apoptosis, applicable in archived paraffin-embedded tissue, have been commercially developed. Potentially useful apoptosis markers include cleaved cytokeratin-18 (c-CK18), cleaved caspase-3 (c-cas-3), cleaved lamin A (c-lam-A), phosphorylated histone H2AX (gammaH2AX), cleaved poly(ADP ribose) polymerase (c-PARP), and translocation of apoptosis-inducing factor (AIF). When tissue samples from freshly resected colon segments were challenged ex vivo with the bile acid deoxycholate, approximately 50% of goblet cells became apoptotic by morphologic criteria. This high level of morphologic apoptosis allowed quantitative comparison with the usefulness and specificity of immunohistochemical markers of apoptosis. The antibody to c-CK18 was almost as useful and about as specific as morphology for identifying apoptotic colonic epithelial cells. Antibodies to c-cas-3, c-lam-A, and gammaH2AX, though specific for apoptotic cells, were less useful. The antibody to c-PARP, though specific for apoptotic cells, had low usefulness, and the antibody to AIF was relatively nonspecific, under our conditions.     

A protein secreted by the respiratory pathogen Chlamydia pneumoniae impairs IL-17 signalling via interaction with human Act1

Chlamydia pneumoniae is a common respiratory pathogen that has been associated with a variety of chronic diseases including asthma and atherosclerosis. Chlamydiae are obligate intracellular parasites that primarily infect epithelial cells where they develop within a membrane-bound vacuole, termed an inclusion. Interactions between the microorganism and eukaryotic cell can be mediated by chlamydial proteins inserted into the inclusion membrane. We describe here a novel C. pneumoniae -specific inclusion membrane protein (Inc) CP0236, which contains domains exposed to the host cytoplasm. We demonstrate that, in a yeast two-hybrid screen, CP0236 interacts with the NFκB activator 1 (Act1) and this interaction was confirmed in HeLa 229 cells where ectopically expressed CP0236 was co-immunoprecipitated with endogenous Act1. Furthermore, we demonstrate that Act1 displays an altered distribution in the cytoplasm of HeLa cells infected with C. pneumoniae where it associates with the chlamydial inclusion membrane. This sequestration of Act1 by chlamydiae inhibited recruitment of the protein to the interleukin-17 (IL-17) receptor upon stimulation of C. pneumoniae -infected cells with IL-17A. Such inhibition of the IL-17 signalling pathway led to protection of Chlamydia -infected cells from NFκB activation in IL-17-stimulated cells. We describe here a unique strategy employed by C. pneumoniae to achieve inhibition of NFκB activation via interaction of CP0236 with mammalian Act1.     

Obesity and Television Watching in Preschoolers in Greece: The GENESIS Study

The aim of the current work was to evaluate the effect of preschoolers' television (TV) watching time on the prevalence of obesity even after controlling for their total energy intake and their physical activity status. A representative sample of 2,374 Greek children aged 1–5 years was examined (“Growth, Exercise and Nutrition Epidemiological Study in preSchoolers”, GENESIS study). Children's TV watching time on a usual weekday and at a usual weekend was recorded. The overall mean of children's TV viewing time was 1.32 h/day. The majority of participants (74.0%) spent <2 h/day watching TV whereas only 3.1% spent >4 h/day in front of a TV set. Overall, 65.2% of participants were normal weight, 17.2% were overweight, and the rest 17.6% were obese. The prevalence of obesity was significantly higher among those with TV viewing time ≥2 h/day (21.7%) compared to those watching TV <2 h/day (16.1%, P = 0.003). TV viewing time remained significantly associated with the likelihood of being obese even after controlling for potential confounders (i.e., socio demographic and other characteristics and physical activity status) only among children aged 3–5 years. However, further adjusting for children's total energy intake revealed that the association between the TV viewing time and the probability of being obese was no longer statistically significant. On the other hand, physical activity status continued to be an independent factor of being obese. The current findings support the hypothesis that the effect of TV viewing time on childhood obesity is independent of physical activity status and may be attributed to the increased total energy intake during TV watching.