Integrated transcriptomic and proteomic profiling of white spruce stems during the transition from active growth to dormancy.
ABSTRACT: In the autumn, stems of woody perennials such as forest trees undergo a transition from active growth to dormancy. We used microarray transcriptomic profiling in combination with a proteomics analysis to elucidate processes that occur during this growth-to-dormancy transition in a conifer, white spruce (Picea glauca [Moench] Voss). Several differentially expressed genes were likely associated with the developmental transition that occurs during growth cessation in the cambial zone and the concomitant completion of cell maturation in vascular tissues. Genes encoding for cell wall and membrane biosynthetic enzymes showed transcript abundance patterns consistent with completion of cell maturation, and also of cell wall and membrane modifications potentially enabling cells to withstand the harsh conditions of winter. Several differentially expressed genes were identified that encoded putative regulators of cambial activity, cell development, and of the photoperiodic pathway. Reconfiguration of carbon allocation figured centrally in the tree’s overwintering preparations. For example, genes associated with carbon-based defenses such as terpenoids were downregulated, while many genes associated with proteinbased defenses and other stress mitigation mechanisms were upregulated. Several of these correspond to proteins that were accumulated during the growth-to-dormancy transition, emphasizing the importance of stress protection in the tree’s adaptive response to overwintering. Two year old white spruce (Picea glauca [Moench] Voss) seedlings were used for all experiments, which were conducted as described by El Kayal et al. (2011). Using a complete randomized block design, seedlings were grown in growth chambers under long days (LD; 16h day / 8h night, 20°C, 50 to 60% RH) for 8-10 weeks. Shortly before seedlings were to begin bud formation, the photoperiod was changed to short days (SD; 8h day / 16h night, 20°C, 50 to 60% RH) to induce rapid and synchronous bud formation. This was designated Day 0. Lignified whole stems representing the current year’s growth (microarrays, microscopy) or previous year’s growth (protein analyses) were sampled at 0, 3, 7, 14, 28 and 70 d (10 wk) SD, and immediately frozen in liquid nitrogen. Remaining plants were maintained in SD for an additional 8-15 wk, and then transferred to low temperatures (LT, 2 - 4°C) for 3 to 4 weeks with continuing SD prior to harvest. These are referred to as LT samples.
Project description:Bud formation is an adaptive trait that temperate forest trees have acquired to facilitate seasonal synchronization. We have characterized transcriptome-level changes that occur during bud formation of white spruce (Picea glauca [Moench] Voss.), a primarily determinate species in which preformed stem units contained within the apical bud constitute most of next season's growth. Microarray analysis identified 4460 differentially expressed sequences in shoot tips during short day-induced bud formation. Cluster analysis revealed distinct temporal patterns of expression, and functional classification of genes in these clusters implied molecular processes that coincide with anatomical changes occurring in the developing bud. Comparing expression profiles in developing buds under long day and short day conditions identified possible photoperiod-responsive genes that may not be essential for bud development. Several genes putatively associated with hormone signalling were identified, and hormone quantification revealed distinct profiles for ABA, cytokinins, auxin and their metabolites that can be related to morphological changes to the bud. Comparison of gene expression profiles during bud formation in different tissues revealed 108 genes that are differentially expressed only in developing buds and show greater transcript abundance in developing buds than other tissues. These findings provide a temporal roadmap of bud formation in white spruce. Shoot tips (terminal buds), needles, and secondary stems were collected from two-year-old white spruce plants over a 10-week time course of 0, 1, 3, 7, 14, 28, and 70 days after switching from 6 to 8 weeks of long daylight photoperiods (LD; 16 hours of light and 8 hours of dark) to short daylight photoperiods (SD; 8 hours of daylight and 16 hours of dark). Remaining plants were kept in short days for an additional 8-15 weeks, and then transferred to low temperature (LT; 2°C to 4°C) for 3 to 4 weeks with continuing SD prior to harvest. Another set of plants was grown and harvested under the same conditions as described above, but remained in LD at all times. Four sets of dye-swap design microarray experiments were conducted. The first set of experiments (samples 1-7) studied the SD time course of buds development. Terminal buds from each time point (1d, 3d, 7d, 14d, 28d, and 70d) and LT were co-hybridized with actively growing shoot tips (0d). The same time point comparison (without LT) of shoot tips from LD-treated trees was carried out as the second set of experiments (samples 8-13). The third experiment (samples 14-20) denoted a separate LD/SD comparison at seven different time points (0d, 1d, 3d, 7d, 14d, 28d, and 70d), and the last experiment (samples 21-26) compared SD shoot tips, needles, and secondary stems with each of the other tissues at 14d and 70d. In each experiment, four biological replicates were used, with two replicates representing the dye-swaps.
Project description:To identify genes involved in the developmental process of Atlantic salmon smoltification, gene expression was compared between smolt and parr in tissues involved in osmoregulation (gill), metabolism (liver), imprinting (olfactory rosettes) and neuroendocrine control (hypothalamus and pituitary). Tissue samples were harvested from laboratory-reared parr and smolts on the same date. Smolts were distinguished from parr by size and appearance; developmental status was confirmed by physiological assays. Eight biological replicates (16 fish) balanced for sex and for dye were used in the liver, gill, olfactory rosette, and hypothalamus comparisons. Four male parr were compared to four male smolts and four female parr were compared to four female smolts; smolts were labeled with Alexa Fluor 555 on four arrays and with Alexa Fluor 647 on four arrays. Six biological replicates (12 fish) were used for the pituitary comparison (two female and four male).
Project description:Exposure to environmental contaminants like nonylphenol can disrupt smolt development and may be a contributing factor in salmon population declines. We used GRASP 16K cDNA microarrays to identify genes that are differentially expressed in the liver, gill, hypothalamus, pituitary, and olfactory rosettes of Atlantic salmon smolts treated with nonylphenol compared to control smolts. Nonylphenol treatment was confirmed using physiological assays: nonylphenol-treatment significantly decreased gill Na+,K+-ATPase activity and plasma cortisol and T3 levels. Microarray analyses were used to compare expression in nonylphenol-injected fish with expression in vehicle-injected fish: eight arrays each for liver, gill, olfactory rosettes, hypothalamus, and pituitary tissues. Total RNA was isolated from the tissues of eight nonylphenol-injected fish (six males and two females) and eight vehicle-injected fish (two males and six females) and reverse transcribed separately (not pooled); each slide represents a biological replicate. For each tissue, the eight arrays were balanced for dye: nonylphenol-injected fish were labeled with Alexa Fluor 555 and vehicle-injected fish were labeled with Alexa Fluor 647 on four slides, nonylphenol-injected fish were labeled with Alexa Fluor 647 and vehicle-injected fish were labeled with Alexa Fluor 555 on four slides. Liver, gill, hypothalamus, pituitary, and olfactory rosette tissues were analyzed separately.
Project description:Identification of a stable gene expression signature with high classifying potential to discriminate post-radiotherapy-induced thyroid tumors (follicular adenomas and papillary carcinomas) from their sporadic counterparts.
Project description:Transcriptional response of Bacillus subtilis to moenomycin in wild-type 168. Bacillus subtilis 168, WT (-MOE) vs. WT (+MOE). The experiment was conducted in triplicate using three independent total RNA preparations. Untreated samples were labeled with Alexa Fluor 555 and moenomycin treated samples were labeled with Alexa Fluor 647.
Project description:Gene expression analyses through cDNA microarray of fifteen gastrocnemius muscles from transgenic and wild-type SOD1G93A mouse model by the ages of 40 and 80 days old were performed. We used a customized cDNA array containing the cDNA platform comprised of 2352 spots, 326 of them orthologous to mouse, 1384 additional human cDNA sequences, 496 negative controls (DMSO) and 48 positive controls (the Q gene from λ-phage). Gene expression results for SOD1G93A and WT age matched mice pointed to eight up- (LOXL2, PIK4CA, FZD9, CUL1, CTNND1, SNF1LK, PRKX, DNER) and nine down-regulated genes (PIK3C2A, RIPK4, ID2, C1QDC1, EIF2AK2, RAC3, CDS1, INPPL1, TBL1X) at 40 days and also to one up- (PIK3CA) and five down-regulated genes (CD44, EEF2K, FZD2, CREBBP, PIKI3R1) at 80 days. Based on differentially expressed genes, analyses for gene priorization were performed and used to construct a network of protein-protein interaction. The network based on the genes of 40 and 80 days old mice was composed by 251 and 531 genes, respectively. GRB2 and SRC were identified as central genes of both networks. In conclusion, changes in gene expression of skeletal muscle from transgenic ALS mice in pre-symptomatic periods give further evidence of early neuromuscular abnormalities that precede motor neuron death. We performed gene expression analyses by customized cDNA array, using reference design, of fifteen gastrocnemius muscles from transgenic and wild-type SOD1G93A mouse model by the ages of 40 and 80 days old. These differentially expressed lists were submitted to analyses for gene priorization and used to construct a network of protein-protein interaction.
Project description:The angio-suppressive effect of 20(R)-ginsenoside Rg3 (Rg3-R) has been previously demonstrated, and microRNAs (miRNAs) are a vital group of small non-coding RNAs that function as post-transcriptional modulator of gene expression. Thus, using human umbilical vein endothelial cells (HUVEC) as model, we compared the microRNA (miRNA) expression profile of vascular endothelial growth factor (VEGF)-induced cells with the profile of the cell co-treated with VEGF and Rg3-R. Among the screened 553 human miRNAs, 6 up-regulated (miR-520h, miR-487b, miR-197, miR-524*, miR-342 and miR-219) and 3 down-regulated (miR-23a, miR-489 and miR-377) miRNAs were detected in Rg3-R treated vascular endothelial growth factor (VEGF)-induced HUVECs compared to VEGF alone. Real time RT-PCR was subsequently performed to verify the miRNA microarray result. Two condition experiment: VEGF-induced HUVEC and VEGF-induced HUVEC treated with Rg3-R. Three independent microarray experiments, with triplicate per microarray.
Project description:Transcriptional profile of the rocG gudB double null mutant during log growth phase in LB medium. Bacillus subtilis W168, WT vs. delta-rocG delta-gudB. The experiment was conducted two times using three independent total RNA preparations (biological triplicates). For each paried comparison, WT was labeled with Alexa Fluor 555 and the rocG gudB double mutant was with Alexa Fluor 647.