Intracellular Calcium Deficits in Drosophila Cholinergic Neurons Expressing Wild Type or FAD-Mutant Presenilin

Much of our current understanding about neurodegenerative diseases can be attributed to the study of inherited forms of these disorders. For example, mutations in the presenilin 1 and 2 genes have been linked to early onset familial forms of Alzheimer''s disease (FAD). Using the Drosophila central nervous system as a model we have investigated the role of presenilin in one of the earliest cellular defects associated with Alzheimer''s disease, intracellular calcium deregulation. We show that expression of either wild type or FAD-mutant presenilin in Drosophila CNS neurons has no impact on resting calcium levels but does give rise to deficits in intracellular calcium stores. Furthermore, we show that a loss-of-function mutation in calmodulin, a key regulator of intracellular calcium, can suppress presenilin-induced deficits in calcium stores. Our data support a model whereby presenilin plays a role in regulating intracellular calcium stores and demonstrate that Drosophila can be used to study the link between presenilin and calcium deregulation.     

Host interference with expression of the lambda N gene product

We have searched among E. coli M72 (D, bio11cI857H1) temperature resistant survivors and have found two bacterial mutants, gro100 and gro101 which block λiλ and λi⁴³⁴ phage development but allow growth of their N-independent derivatives λiλ nin and λi⁴³⁴nin. It is not known yet whether these two mutants interfere with the production of the N gene product or with its function. At least part of the gro genotype maps at 12′ of the E. coli genetic map and is co-transductible by Pl with the lac locus.     

Understorey vegetation moderates climate in open forests: The role of the skirt-forming grass tree Xanthorrhoea semiplana F.Muell

Microsites are created by abiotic and biotic features of the landscape and may provide essential habitats for the persistence of biota. Forest canopies and understorey plants may moderate wind and solar radiation to create microclimatic conditions that differ considerably from regional climates. Skirt-forming plants, where senescent leaves create hut-like cavities around the stem, create microsites that are sheltered from ambient conditions and extreme weather events, constituting potential refuges for wildlife. We investigate day and night temperatures and humidity for four locations (grass tree cavities, soil, 20 cm above-ground, 1 m above-ground) in a South Australian forest with relatively open canopy of stringybark eucalypts (Eucalyptus baxteri, E. obliqua) and an understorey of skirt-forming grass trees (Xanthorrhoea semiplana) at 5, 10, 20, and 40 m from the forest edge. We also measured the percentage of canopy and understorey covers. Generally, temperature and humidity differed significantly between more sheltered (grass tree cavities, soil) and open-air microsites, with the former being cooler during the day and warmer and more humid during the night. Furthermore, our results suggest that canopy cover tends to decrease, and understorey cover tends to increase, the temperature of microsites. Distance to the edge was not significantly related to temperature for any microsite, suggesting that the edge effect did not extend beyond 10 m from the edge. Overall, grass trees influenced microclimatic conditions by forming a dense understorey and providing cavities that are relatively insulated. The capacity of grass tree cavities to buffer external conditions increased linearly with ambient temperatures, by 0.46°C per degree increase in maximum and 0.25°C per degree decrease in minimum temperatures, potentially offsetting climate warming and enabling persistence of fauna within their thermal limits. These climate moderation properties will make grass trees increasingly important refuges as extreme weather events become more common under anthropogenic climate change.     

Reconstruction of the proximal ends of retiolitid rhabdosomes (Graptolithina) from the Upper Wenlock and the Lower Ludlow

Detailed study of the ultrastructures on the cortical lists of retiolitids occurring after the lundgreni event has been undertaken. The extremely well preserved material from the Go?dap borehole of Poland (Baltica) enables classification of clathrial lists into two types—with single and double seams. Significantly different seam development is observed between two groups of retiolitids occurring before and after the lundgreni event. The study of seams and increments on the lists enables reconstruction of the membrane arrangement of the rhabdosomes. Reconstruction of the proximal ends, the arrangement of the ancora umbrella, and the layout of the proximal ventral and lateral orifices of five genera, Neogothograptus, Holoretiolites, Plectograptus, Spinograptus, and Quattuorgraptus n. gen., is presented. The new genus Quattuorgraptus is separated from Spinograptus because of the different development of the ancora umbrella and the width of the lateral walls of the rhabdosome.     

Heterogeneity of 11q13 region rearrangements in laryngeal squamous cell carcinoma analyzed by microarray platforms and fluorescence in situ hybridization

We reinvestigated rearrangements occurring in region q13 of chromosome 11 aiming to: (i) describe heterogeneity of the observed structural alterations, (ii) estimate amplicon size and (iii) identify of oncogenes involved in laryngeal cancer progression as potential targets for therapy. The study included 17 cell lines derived from laryngeal cancers and 34 specimens from primary laryngeal tumors. The region 11q13 was analyzed by fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH) and gene expression microarray. Next, quantitative real time PCR was used for chosen genes to confirm results from aCGH and gene expression microarray. The observed pattern of aberrations allows to distinguish three ways, in which gain and amplification involving 11q13 region may occur: formation of a homogeneously staining region; breakpoints in/near 11q13, which lead to the three to sevenfold increase of the copy number of 11q13 region; the presence of additional copies of the whole chromosome 11. The minimal altered region of gain and/or amplification was limited to ~1.8 Mb (chr.11:69,395,184–71,209,568) and comprised mostly 11q13.3 band which contain 12 genes. Five, out of these genes (CCND1, ORAOV1, FADD, PPFIA1, CTTN) had higher expression levels in comparison to healthy controls. Apart from CCND1 gene, which has an established role in pathogenesis of head and neck cancers, CTTN, ORAOV1 and FADD genes appear to be oncogene-candidates in laryngeal cancers, while a function of PPFIA1 requires further studies.     

Impact of osmotic stress on physiological and biochemical characteristics in drought-susceptible and drought-resistant wheat genotypes

In this study, the seedlings of two wheat cultivars were used: drought-resistant Chinese Spring (CS) and drought-susceptible (SQ1). Seedlings were subjected to osmotic stress in order to assess the differences in response to drought stress between resistant and susceptible genotype. The aim of the experiment was to evaluate the changes in physiological and biochemical characteristics and to establish the optimum osmotic stress level in which differences in drought resistance between the genotypes could be revealed. Plants were subjected to osmotic stress by supplementing the root medium with three concentrations of PEG 6000. Seedlings were grown for 21 days in control conditions and then the plants were subjected to osmotic stress for 7 days by supplementing the root medium with three concentrations of PEG 6000 (D1, D2, D3) applied in two steps: during the first 3 days of treatment ?0.50, ?0.75 and ?1.00 and next ?0.75, ?1.25 and ?1.5 MPa, respectively. Measurements of gas exchange parameters, chlorophyll content, height of seedlings, length of root, leaf and root water content, leaf osmotic potential, lipid peroxidation, and contents of soluble carbohydrates and proline were taken. The results highlighted statistically significant differences in most traits for treatment D2 and emphasized that these conditions were optimum for expressing differences in the responses to osmotic stress between SQ1 and CS wheat genotypes. The level of osmotic stress defined in this study as most suitable for differentiating drought resistance of wheat genotypes will be used in further research for genetic characterization of this trait in wheat through QTL analysis of mapping population of doubled haploid lines derived from CS and SQ1.