Project description:Over recent decades the progression of natural autumnal senescence has been increasingly delayed across wide areas of the Northern Hemisphere and is thought to be caused by rising temperature. Recently this delay has been shown to be partly attributable to rising atmospheric carbon dioxide concentrations [CO2]. Here, for the first time, we present a possible mechanistic explanation for this phenomenon. Using a plantation of Populus x euramericana grown at elevated [CO2] (e[CO2]) using Free-Air CO2 Enrichment (FACE) technology, we investigated the molecular and biochemical basis underlying this response. Using a poplar cDNA microarray where late growing season and senescing leaves from ambient [CO2] (a[CO2]) and e[CO2] were compared, revealed unique increases and decreases in transcript abundance in the e[CO2] treatment. Growth at e[CO2]caused the greatest increase in the abundance of transcripts catalysing steps in the anthocyanin biosynthetic pathway and an increase in leaf anthocyanin content. Leaf sucrose and starch content were also increased during senescence in e[CO2] and associated with a higher abundance of transcripts in the sucrose and starch biosynthetic pathways. We propose that in e[CO2], autumnal photosynthesis and sugar accumulation results in changes in genes expression that include further investment in secondary carbon metabolism leading to anthocyanin production. This enables prolonged leaf longevity during natural autumnal senescence through increased availability of carbon and improved stress tolerance while in contrast this may also have a negative effect on the control of dormancy. Samples GSM398292..GSM398314 (late senescence samples only): Six replicate trees were labelled in the unfertilised sub-plots of plots 1-4 in the POP/EUROFACE site (http://www.unitus.it/euroface/) and the 10th leaf down from the closed apical bud of the dominant branch were labelled. Leaves were sampled to liquid nitrogen (18th October 2004) and stored at -80 oC. Extracted RNA was tested for quality and quantity and of that passing the test equal quantities of RNA from each replicate were taken and each sample from the control plots (plots 2 and 3) were randomly paired with a sample from and elevated CO2 plot (plots 1 and 4). From the resulting 9 dual channel hybridisations 6 had the control sample in the Cy3 channel and 3 had the elevated CO2 sample in the Cy3 channel. The 6 samples with Cydye orientation as Cy3=control (ambient CO2) and Cy5 = treated (elevated CO2) are as follows: GSM398296, GSM398301, GSM398303, GSM398304, GSM398305 and GSM398306. The 3 samples with dye swap i.e Cy3 = treated (elevated CO2) are as follows and Cy5 = control (ambient CO2) are as follows: GSM398292, GSM398313 and GSM398314. Samples GSM398426..GSM398474: Four replicate leaves per sub-plot were sampled and flash frozen into liquid nitrogen, on 31 August 2004, and prior to visible senescence but around the time of bud-set as given by Calfapietra et al., (2003) [1]. The tenth leaf down the dominant stem (which represented the first fully expanded mature leaf of maximum size) from a reference leaf of 30 mm in length (leaf one) were selected. On the 14th September twenty trees from within each experimental plot were taken. The tenth leaf down the dominant stem (which represented the first fully expanded mature leaf of maximum size) from a reference leaf of 30 mm in length (leaf one) were labelled on the main-stem above the petiole. All labelled leaves were a uniform height (approx 0.3 m) from the canopy top across all treatments and not shaded by the canopy. Four replicate leaves from within each sub-plot were sampled during each harvest (except on 18th October when six replicate leaves were sampled). Each sampling time was restricted to two hours within the same day and across sampling day’s uniform cloud free skies were chosen. September samplings took place between 15.00 and 17.00 when climatic variables were generally consistent; later in the season time of sampling was adjusted to an earlier two hour period after mid-day when climatic variables were generally consistent. A chlorotic canopy was evident in plots five and six, as described by Liberloo et al. (2007) therefore any subsequent analysis was for plots one to four only. Six replicate labelled leaves were sampled (as above) from each sub-plot on 18th October 2004

Project description:It is now well established that mature mammalian spermatozoa carry a population of mRNA molecules, at least some of which are transferred to the oocyte at fertilisation. However, the function of the sperm transcriptome remains largely unclear. To shed light on the evolutionary conservation of this feature of sperm biology, we analysed highly purified populations of mature sperm from the fruitfly, Drosophila melanogaster. As with mammalian sperm, we found a consistently enriched population of mRNA molecules that are not likely to be derived from contaminating somatic cells or immature sperm. Using tagged transcripts for three of the spermatozoal mRNAs, we demonstrate that they are transferred to the oocyte at fertilisation and can be detected at least until the onset of zygotic gene expression. We find a remarkable conservation in the functional annotations associated with fly and human spermatozoal mRNAs, in particular a highly significant enrichment for transcripts encoding Ribosomal Proteins. The identification of a conserved set of spermatozoal transcripts opens the possibility of using the power of Drosophila genetics to address the function of this enigmatic class of molecules. RNA extracted from three biological replicates of purified sperm (Sperm rep1, Sperm rep2 and Sperm rep3) was used as a template for oligo-dT-primed reverse transcription, amplification, labelling of dye swapped technical replicates and hybridisation to long oligonucleotides microarrays. As a control, RNA from two biological replicates of dissected adult testis plus accessory glands (Testis_rep1, Testis_rep2) was amplified, labelled (dye-swap technical replicate) and hybridised to similar arrays. To help with the spot-finding of the arrays genomic DNA was co-hybridised in some cases (this genomic DNA data was excluded from further analysis). Genes with an intensity level below 200 in at least one channel across the Sperm or Testis set were removed (5579 transcripts present in all three sperm replicates, 5358 transcripts from the testis/accessory gland samples and 4295 transcripts common to both data sets). Then the quantile normalisation was independently applied to the Sperm replicate samples and Testis replicates.

Project description:Arabidopsis thaliana plants (ecotype Landsberg erecta) were grown at 20ËC constant temperature, 8 hr/16 hr Light/Dark photoperiod at 50-60% ambient humidity, for 8 to 9 weeks. Short day conditions prevented the onset of flowering and the plants were thus maintained in growth stage 1 (leaf production) with 13 to 15 rosette leaves larger than 1mm (stage 1.13 to 1.14). Diamondback moth (DBM, Plutella xylostella) larvae were maintained on cabbage (Brassica oleracea) plants in a climate-controlled room at 25ÂºC, 12 hr photoperiod with 50%-60% relative humidity. Two days before exposing A. thaliana plants to herbivore treatment, plants were transferred to a climate-controlled room (22ÂºC, 50-60% humidity, 12 hr photoperiod). For insect treatment, seven Diamondback moth (DBM, Plutella xylostella) larvae (third to fifth instars) were placed on a group of four or five plants until time of harvest, for each time point separately. All rosette leaves were harvested at 1h, 4h, 12h, and 24h after onset of continuous herbivory and flash frozen in liquid nitrogen. Control plants were maintained under the same conditions and harvested in parallel. Keywords: time course, stress response, herbivory response For each time point (1h, 4h, 12h, and 24h) two biological replicates (DBM treatment) were performed. Control plants were harvested in parallel. Total RNA from each sample was used for two labelling reactions using dye-flips (Cy5 or Cy3) and labelled cDNA from treatment and control plants were co-hybridized. Thus, for each time-point four replicates were analyzed each comparing treatment with the corresponding control (rep1 and rep2 are dye-flips of biological replicate 1, and rep3 and rep4 are dye-flips of biological replicate 2). For background correction, we defined the mean of the lowest 10% of spot intensities from a particular subgrid as the background for that subgrid. This mean was subtracted from each spot in the subgrid. Signal intensities that did not exceed the background plus 3 standard deviations thereof were defined as not detectable and were excluded from further analyses. We normalized using loess curves thus generating log2 transformed expression ratios comparing DBM treatment with control. These ratios are given in the VALUE columns of each array.

Project description:Analysis of differential gene expression in third instar Drosophila salivary glands in the absence versus presence of cohesin. ABSTRACT: Developmental abnormalities observed in Cornelia de Lange Syndrome (CdLS) have been genetically linked to mutations in the cohesin machinery. These findings raise the possibility that cohesin, in addition to its canonical function of mediating sister chromatid cohesion, might also be involved in regulating gene expression. We report that cleavage of cohesinM-CM-^Us kleisin subunit in post-mitotic Drosophila salivary glands induces major changes (both up and down) in the transcript levels of many genes. Kinetic analyses of changes in transcript levels upon cohesin cleavage reveal that a subset of genes responds to cohesin cleavage within a few hours. In addition, cohesin binds to most of these loci, suggesting that cohesin is directly regulating their expression. Amongst these genes are several that are regulated by the steroid hormone Ecdysone. Transcripts at EcR and Eip74EF, which encode an Ecdysone Receptor and an Ecdysone-regulated transcription factor, respectively, decline ten-fold within four hours of cohesin cleavage. Cytological visualization of transcription at selected Ecdysone-responsive genes reveals that puffing at Eip74EF ceases within an hour or two of cohesin cleavage, long before any decline in EcR associated with this locus. We conclude that cohesin regulates expression of a distinct set of genes, including those mediating the Ecdysone response. A heat-inducible transgene (hs-TEV) was used to induce TEV in terminally differentiated third instar Drosophila salivary glands expressing either wild type (+ cohesin) or TEV-cleavable myc10-tagged Rad21 protein (Rad21TEV, - cohesin). Total RNA was isolated from + and - cohesin salivary glands 10-12 hours after heat shock induction of TEV (7 independent biological samples each). RNA samples were converted to cDNA, labeled with Cy3 and Cy5 respectively (3x) and vice versa (4x; dye swaps), and hybridized to INDAC FL003 arrays. Analysis of seven arrays, each hybridized to an independently generated sample-pair revealed major differences in transcript levels between + and - cohesin samples.

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Ozone Exposure of Populus

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