Structure elucidation and phytotoxicity of ecdysteroids from Chenopodium album

The leaves of Chenopodium album were infused in H2O/MeOH. The extract treated with cold acetone gave heavy precipitation, which was removed by centrifugation. Solid material was fractionated into acidic and neutral fractions. The acidic material was subjected to different silica-gel column chromatographies, and then it was purified by reversed-phase HPLC to afford four known ecdysteroids and the new 3beta,14alpha-dihydroxy-5beta-pregn-7-ene-2,6,20-trione that were characterized by extensive spectroscopic investigation, especially by 1D- and 2D-NMR. Their effects on germination and growth of Lactuca sativa L. have been studied. The results are reported as percentage differences of germination, root elongation and shoot elongation, from the control at concentrations ranging from 10(-4) to 10(-7) M.     

Protein oligomerization modulates raft partitioning and apical sorting of GPI-anchored proteins

An essential but insufficient step for apical sorting of glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) in epithelial cells is their association with detergent-resistant microdomains (DRMs) or rafts. In this paper, we show that in MDCK cells both apical and basolateral GPI-APs associate with DRMs during their biosynthesis. However, only apical and not basolateral GPI-APs are able to oligomerize into high molecular weight complexes. Protein oligomerization begins in the medial Golgi, concomitantly with DRM association, and is dependent on protein-protein interactions. Impairment of oligomerization leads to protein missorting. We propose that oligomerization stabilizes GPI-APs into rafts and that this additional step is required for apical sorting of GPI-APs. Two alternative apical sorting models are presented.     

Activity of protein phosphatase calcineurin is decreased in sporadic and familial amyotrophic lateral sclerosispatients

Calcineurin (CaN) is a Ser/Thr protein phosphatase involved in a wide range of cellular responses to calcium mobilizing signals. Previous evidence supports the notion that calcineurin is oxidatively inhibited by mutant Cu, Zn superoxide dismutase (SOD1) typical of familial ALS patients in vitro and in transgenic mice. We report that calcineurin activity is markedly inhibited in lymphocytes from 37 sporadic, eight familial ALS patients and an asymptomatic subject carrying an SOD1 mutation as compared to 28 healthy controls. Two other healthy subjects, heterozygous for the D90A mutation from a recessive pedigree, have normal calcineurin activity. Immunoreactive CaN protein, age, sex and riluzole treatment are not related to calcineurin activity in samples from patients. However, we have observed a marked increase in total protein oxidation in extracts from ALS lymphocytes, as compared to extracts from control subjects. These data confirm that modification of calcineurin activity and possibly of calcineurin-mediated pathways of signal transduction (including modulation of apoptotic neuronal death) may contribute to the pathogenesis of ALS.     

Characterization of tissue specific expression of Notch-1 in human tissues

Signaling through the Notch cell surface receptors is a highly conserved mechanism of cell fate specification. Notch signaling regulates proliferation, differentiation and cell death. In vertebrates, putative gene duplication has originated four Notch genes, Notch-1, -2, -3 and -4. They have been implicated in neurogenesis, hematopoiesis, T-cell development, vasculogenesis and brain cortical growth. We have investigated Notch-1 distribution in normal human tissues by immunohistochemistry and immunoblot. We detected widespread expression of Notch-1 cytoplasmatic staining, with different tissue distributions in the different organs examined. In particular, high expression of Notch-1 was detected in the intermediate suprabasal layers, but not in the dead cells at the extreme periphery of stratified epithelia. Moreover, a low/intermediate level of Notch-1 was observed in lymphocytes in several peripheral lymphoid tissues; in particular the germinal centers of lymph nodes showed the most abundant number of positive cells, which appeared to be centroblasts/immunoblasts based on nuclear morphology. Notch-1 participates in keratinocytes differentiation. We showed by Western blot analysis that Notch-1 level was clearly increased in HaCaT cells after Ca(++) addition and remained substantially elevated until late differentiation stages. These results suggest that Notch-1 may function in numerous cell types in processes beyond cell fate determination, such as neuronal plasticity, muscle hypertrophy, liver regeneration, and germinal center lymphopoiesis during the immune response.     

Stimulation of hyphal growth in anaerobic cultures of Mucor rouxii by extracellular trehalose. Relevance of cell wall-bound activity of acid trehalase for trehalose utilization

We investigated whether cellular responses to various stress conditions are regulated in synchronization with the ultradian rhythm of respiratory-fermentative metabolism which is coupled to the cell cycle rhythm in continuous cultures of the yeast Saccharomyces cerevisiae. The cellular resistance to heat oscillated with a peak at the late respiro-fermentative phase, which approximately corresponds to the unbudding period of the cell cycle. Cellular resistance to H(2)O(2) and that to the superoxide-generating agent menadione oscillated in the same phase as that of heat resistance. The resistance to cadmium and that to 1-chloro-2,4-dinitrobenzene, an uncoupler of energy metabolism in mitochondria, both oscillated with a peak advanced by about 80 degrees relative to that of heat resistance, approximately covering the respiro-fermentative phase. Thus, cellular resistance to various stresses in S. cerevisiae oscillated in synchronization with the metabolic oscillation in the continuous culture.     

The interplay among psychopathology,personal resources,context‐related factors and real‐life functioning in schizophrenia: stability in relationships after 4 years and differences in network structure between recovered and non‐recovered patients

Improving real‐life functioning is the main goal of the most advanced integrated treatment programs in people with schizophrenia. The Italian Network for Research on Psychoses previously explored, by using network analysis, the interplay among illness‐related variables, personal resources, context‐related factors and real‐life functioning in a large sample of patients with schizophrenia. The same research network has now completed a 4‐year follow‐up of the original sample. In the present study, we used network analysis to test whether the pattern of relationships among all variables investigated at baseline was similar at follow‐up. In addition, we compared the network structure of patients who were classified as recovered at follow‐up versus those who did not recover. Six hundred eighteen subjects recruited at baseline could be assessed in the follow‐up study. The network structure did not change significantly from baseline to follow‐up, and the overall strength of the connections among variables increased slightly, but not significantly. Functional capacity and everyday life skills had a high betweenness and closeness in the network at follow‐up, as they had at baseline, while psychopathological variables remained more peripheral. The network structure and connectivity of non‐recovered patients were similar to those observed in the whole sample, but very different from those in recovered subjects, in which we found few connections only. These data strongly suggest that tightly coupled symptoms/dysfunctions tend to maintain each other's activation, contributing to poor outcome in schizophrenia. Early and integrated treatment plans, targeting variables with high centrality, might prevent the emergence of self‐reinforcing networks of symptoms and dysfunctions in people with schizophrenia.     

Phorophyte size and soil profiles differentially correlate with community structure among hemiepiphytes and nomadic vines

Tropical non-self-supporting plants such as hemiepiphytes and nomadic vines are model organisms for disentangling biotic and environmental correlates which influence their occupancy patterns. We inventoried >4000 individuals from >3000 trees ranging from 1 to 200 cm diameter at breast height (DBH) in a northeastern Amazonian upland forest to address how tree (phorophyte) size, edaphic factors and recruitment strategy influence occupancy, diversity, and compositional patterns of two vascular non-self-supporting plant functional groups. Hemiepiphytes germinate on phorophytes prior to establishing soil connections, whereas nomadic vines initiate their life cycle on the forest floor and subsequently climb phorophytes for crown access, abandoning roots replaced by adventitious connections which may reach the ground. Our results show that larger phorophytes (≥30 cm DBH) supported more species for both hemiepiphytes and nomadic vines. However, nomadic vines' occupancy probabilities saturated faster at smaller stem sizes than that of hemiepiphytes indicating differential preferences for stem sizes among the two functional groups. For smaller phorophytes (<30 cm DBH), soil correlations were stronger with nomadic vines than hemiepiphytes, whereas no significant differences were detected among functional groups in relation to edaphic factors for larger (≥ 30 cm DBH) ones. Finally, a small core group of species showed disproportionately greater abundances among large phorophytes suggesting that autogenic processes differentially promote survivability. Such interactions among phorophyte size and edaphic factors may result from the contrasting ecological requirements of hemiepiphytes and nomadic vines at the recruitment stage, demonstrating the necessity for elaborate demographic-based studies to better understand these complex plant–plant interactions. Abstract in Spanish is available with online material