The Arabidopsis thaliana NAC domain transcription factor, VASCULAR-RELATED NAC-DOMAIN7 (VND7), acts as a key regulator of xylem vessel differentiation. In order to identify direct target genes of VND7, we performed global transcriptome analysis using Arabidopsis transgenic lines in which VND7 activity could be induced post-translationally. This analysis identified 63 putative direct target genes of VND7, which encode a broad range of proteins, such as transcription factors, IRREGULAR XYLEM proteins and proteolytic enzymes, known to be closely associated with xylem vessel formation. Recombinant VND7 protein binds to several promoter sequences present in candidate direct target genes: specifically, in the promoter of XYLEM CYSTEINE PEPTIDASE1, two distinct regions were demonstrated to be responsible for VND7 binding. We also found that expression of VND7 restores secondary cell wall formation in the fiber cells of inflorescence stems of nst1nst3 double mutants, as well as expression of NAC SECONDARY WALL THICKENING PROMOTING FACTOR3 (NST3, however, the vessel-type secondary wall deposition was observed only as a result of VND7 expression. These findings indicated that VND7 upregulates, directly and/or indirectly, many genes involved in a wide range of processes in xylem vessel differentiation, and that its target genes are partially different from those of NSTs.
VASCULAR-RELATED NAC-DOMAIN7 directly regulates the expression of a broad range of genes for xylem vessel formation.
Age, Specimen part, Treatment
View SamplesPlants grown under a canopy recognize changes in light quality and modify their growth patterns; this modification is known as shade avoidance syndrome. In leaves, leaf blade expansion is suppressed, whereas petiole elongation is promoted under the shade. However, the mechanisms that control these responses are largely unclear. Here, we demonstrated that both auxin and brassinosteroid (BR) are required for the normal leaf responses to shade. The microarray analysis of leaf blades and petioles treated with end-of-day far-red light (EODFR) revealed that almost half of the genes induced by the treatment in both parts were previously identified as auxin-responsive genes. Likewise, BR-responsive genes were overrepresented in the EODFR-induced genes. Hence, the auxin and BR responses were elevated by EODFR treatment in both leaf blades and petioles, although opposing growth responses were observed in these two parts. The analysis of the auxin-deficient doc1/big mutant and BR-deficient rot3/cyp90c1 mutant further indicates that auxin and BR were equally required for the normal petiole elongation response to the shade stimulus. In addition, the spotlight irradiation experiment revealed that phytochrome in leaf blades but not that in petioles regulated petiole elongation, which was probably mediated through regulation of the auxin/BR responses in petioles. On the basis of these findings, we conclude that auxin and BR cooperatively promote petiole elongation in response to the shade stimulus under the control of phytochrome in the leaf blade.
Involvement of auxin and brassinosteroid in the regulation of petiole elongation under the shade.
Specimen part
View SamplesDevelopment of a flat structure of leaves depend on active expansion of leaf blades mediated by cell proliferation. The angustifolia3 (an3) mutants of Arabidopsis thaliana are defective in cell proliferation in leaf primorida. AN3 encodes a transcription coactivator and interacts with a putative transcription factor AtGRF5. To investigate how AN3 control cell proliferation, we compared gene expression profiles between an3 and wild type. This analysis provide an insight into AN3-dependent cell proliferation pathway.
ANGUSTIFOLIA3 plays roles in adaxial/abaxial patterning and growth in leaf morphogenesis.
No sample metadata fields
View SamplesIn sexual reproduction, a proper communication and cooperation between male and female organs and tissue are essential for male and female gametes to unite. In flowering plants, female sporophytic tissues and gametophyte direct a male pollen tube towards an egg apparatus, which consists of an egg cell and two synergid cells. The cell-cell communication between the pollen tube and the egg apparatus, such as the reception of a signal from the egg apparatus at the pollen tube, makes the tip of pollen tube rapture to release the sperm cell. To isolate male factors involved in the interaction between a pollen tube and an egg apparatus, we focused on receptor-like kinases (RLKs), which are extensively diversified in the flowering plant lineage to comprise a large monophyletic gene family. Approximately 620 members were found in the Arabidopsis thaliana genome. Expression patterns of 558 RLKs were analyzed using an Affymetrix ATH1 microarray of A. thaliana. We focused on two RLKs, ANXUR1 (ANX1) and ANXUR2 (ANX2), and characterized their function. Here we report that pollen tubes of anx1/anx2 ruptured before arriving at the egg apparatus, suggesting that ANX1 and ANX2 are male factors controlling pollen tube behavior with directing rupture at proper timing. Furthermore, ANX1 and ANX2 were the most closely related paralogs to a female factor FERONIA/SIRENE controlling pollen tube behavior expressed in synergid cells. Our finding shows that the coordinated behaviors of female and male reproductive apparatuses are regulated by the sister genes, whose duplication might play a role in the evolution of fertilization system in flowering plants.
ANXUR1 and 2, sister genes to FERONIA/SIRENE, are male factors for coordinated fertilization.
No sample metadata fields
View SamplesAnalysis of calli derived from the wild type (Ler), the ckh1 and ckh2 mutants cultured on media in the absence of cytokinin (control), in the presence of low (25 ng/ml kinetin) or high (200 ng/ml kinetin) levels of cytokinin, or in the presence of Trichostatin A (TSA). In these conditions, a constant 2,4-dichlorophenoxyacetic acid (2,4-D) was included as an auxin.
The CKH2/PKL chromatin remodeling factor negatively regulates cytokinin responses in Arabidopsis calli.
Disease, Treatment
View SamplesPlants typically contain two different types of cell walls: a primary wall that is being deposited around all growing cells, and a secondary wall that is produced in cells with specialized functions once they have ceased to grow. In Arabidopsis, VND7 is a transcription factor that is sufficient to activate secondary cell wall synthesis. To artificially turn on the secondary cell wall synthesis, VND7 was fused to the activation domain of the herpes virus VP16 protein and the glucocorticoid receptor (GR) domain. Thus, the transgenic plants harbouring the constructs can then be treated with dexamethasone (DEX), a glucocorticoid derivative, to induce the secondary cell wall formation.
A Transcriptional and Metabolic Framework for Secondary Wall Formation in Arabidopsis.
Specimen part, Treatment
View SamplesR1R2R3-Myb proteins represent an evolutionarily conserved class of Myb family proteins important for cell cycle regulation and differentiation in eukaryotic cells. In plants, this class of Myb proteins are believed to play important roles in cell cycle regulation through transcriptional regulation of G2/M phase-specific genes by binding to common cis-elements, called MSA elements. In Arabidopsis thaliana, MYB3R1 and MYB3R4 act as transcriptional activators and positively regulate cytokinesis by activating transcription of KNOLLE, which encodes a cytokinesis-specific syntaxin. Here, we show that the double mutation myb3r1 myb3r4 causes pleiotropic developmental defects, some of which are due to deficiency of KNOLLE whereas other are not, suggesting multiple target genes are involved. Consistently, microarray analysis of the double mutant revealed altered expression of many genes, among which G2/M-specific genes showed significant overrepresentation of the MSA motif and a strong tendency to be down-regulated by the double mutation. Our results demonstrate, on a genome-wide level, the importance of the MYB3R-MSA pathway for regulating G2/M-specific transcription. In addition, MYB3R1 and MYB3R4 may have diverse roles during plant development by regulating G2/M-specific genes with various functions, as well as genes possibly unrelated to the cell cycle.
Mutations in MYB3R1 and MYB3R4 cause pleiotropic developmental defects and preferential down-regulation of multiple G2/M-specific genes in Arabidopsis.
Age, Specimen part
View SamplesTemporal and spatial regulation of cell division is central for generating multicellular organs with predictable sizes and shapes. However, it remains largely unclear how genes with mitotic functions are transcriptionally regulated during organogenesis in plants. Here, we showed that a group of R1R2R3-Myb transcription factors are responsible for developmentally controlled downregulation of variety of mitotic genes in Arabidopsis. Loss of their functions resulted in elevated expression of mitotic genes in quiescent cells including those underwent terminal differentiation. Concomitantly, their mutations enhanced cell division activities in various aspects of plant development, generating organs with increased sizes and irregular architectures. In addition, we showed that this type of R1R2R3-Myb proteins are required for oscillated expression of G2/M-specfiic genes, most likely by inhibiting transcription outside of G2/M in the cell cycle. Our finding uncovered a novel plant-specific mechanism in which scheduled expression of G2/M-specific genes may require their global repression both in the cell cycle and during development.
Transcriptional repression by MYB3R proteins regulates plant organ growth.
Specimen part
View SamplesThe study has been described in the following paper: Gianni Parise, Stuart M. Phillips, Jan J. Kaczor and Mark A. Tarnopolsky (2005). Antioxidant enzyme activity is up-regulated after unilateral resistance exercise training in older adults. Free Radical Biology and Medicine, Volume 39, Issue 2, 15 July 2005, Pages 289-295 We cite the following three paragraphs from this paper: "MATERIALS AND METHODS Subjects Twelve men (71.2 ± 6.5 y) volunteered to participate in a 12 week uni-lateral leg resistance training program (Table 1). All subjects underwent a thorough screening process before being admitted into the study. Subjects were first screened by telephone, and were then subject to a medical evaluation. Consent from their family physician was required, and then all potential subjects underwent a resting electrocardiogram, and a sub-maximal graded exercise test on a bicycle ergometer witih a 12-lead ECG. Exclusion criteria included: evidence of coronary hear disease; congestive heart failure; uncontrolled hypertension; chronic obstructive pulmonary disease; diabetes mellitus; renal failure; major orthopaedic disability; and smoking. None of the subjects had ever participated in a structured exercise program. After subjects were advised of the benefits and risks of participation, subjects gave their written informed consent. The study was approved by the McMaster University and Hamilton Health Sciences Research Ethics Board and conferred to the principles of the declaration of Helsinki. Exercise Training Resistance training was performed three times weekly on non-consecutive days (Monday, Wednesday, and Friday) for 12 weeks, under strict supervision. Prior to and after each training session subjects were required to perform passive stretching. Resistance exercise for each session consisted of 3 sets of 10 repetitions for each of leg press and leg extension. Training progressed from one set of each exercise at 50% of the initial 1 repetition maximum (1RM) to 3 sets at 80% of 1RM over the training period. Training logs were kept to record the volume and intensity of each session. The 1RM was re-evaluated every 2 weeks, and the training load was adjusted accordingly. All exercises were performed on universal strength training equipment (Universal Gym Equipment, Inc., Cedar Rapids, Iowa). Muscle Biopsy A muscle biopsy was taken from the vastus lateralis muscle of both legs before as well as after the training period, 20 cm proximal to the knee joint using a modified Bergström needle (5 mm diameter) with suction modification. The biopsy specimen was dissected of fat and connective tissue and immediately frozen in liquid nitrogen. All samples were stored at -80 °C for subsequent analysis. All subjects were required to abstain from strenuous physical activity for 48 hours prior to the testing session. The non-trained leg performed an acute bout of exercise at the same relative intensity of the training leg to allow for the determination of the effect of training and the effect of acute resistance exercise." Additional Notes: 1) The samples of 8 out 12 were used in the gene expression study. 2) The 2 factors in this study are: 2.1) Leg - Left or Right 2.2) Training - Baseline: samples taken on each leg before exercise - Resistance Training: one of the legs was subject to resistance training followed by acute exercise - Acute Exercise: the other leg had only the acute exercise 3) The baseline samples will be used for right versus left leg comparison to see variance between legs for human experimentation technical issues. The samples from Resistance or Acute Exercise will be compared to corresponding baseline samples to evaluate the effect of both exercise programs on gene expression.
Gene expression, fiber type, and strength are similar between left and right legs in older adults.
Sex, Age, Specimen part, Subject
View SamplesMyeloproliferative neoplasms are frequently associated with aberrant constitutive tyrosine kinase (TK) activity resulting from point mutations or chimaeric fusion genes, such as BCR ABL1 or JAK2 V617F. We report here for the first time in hematological malignancies, two novel fusion genes involving the TK RET, BCR-RET and FGFR1OP-RET, in chronic myelo monocytic leukemia (CMML) cases. The two RET fusion genes lead to the aberrant activation of RET, are able to transform hematopoietic cells and skew the hematopoietic differentiation program towards the monocytic/macrophage lineage. We also report that the BCR-RET fusion protein is insensitive to Imatinib but sensitive to Sorafenib in vivo. CMML is an hematopoietic malignancy associated with the frequent activation of the RAS pathway. The RET fusion genes seems to constitutively mimic the same signaling pathway than RAS mutations. Overall, the RET fusion genes behaviors in the monocytic lineage underlie the role of the normal RET TK activity during the physiological monocytic differentiation.
RET fusion genes are associated with chronic myelomonocytic leukemia and enhance monocytic differentiation.
Cell line
View Samples