Flower opening is essential for pollination and thus successful sexual reproduction; however, the underlying mechanisms of its timing control remain largely elusive. We identify a unique cucumber (Cucumis sativus) line '6457' that produces normal ovaries when nutrients are under-supplied, and super ovaries (87%) with delayed corolla opening when nutrients are oversupplied. Corolla opening in both normal and super ovaries is divided into four distinct phases, namely the green bud, green-yellow bud, yellow bud, and flowering stages, along with progressive color transition, cytological tuning, and differential expression of 14,282 genes. In the super ovary, cell division and cell expansion persisted for a significantly longer period of time; the expressions of genes related to photosynthesis, protein degradation, and signaling kinases were dramatically upregulated, whereas the activities of most transcription factors and stress-related genes were significantly down-regulated; concentrations of cytokinins (CKs) and gibberellins were higher in accordance with reduced cytokinin conjugation and degradation and increased expression of gibberellin biosynthesis genes. Exogenous CK application was sufficient for the genesis of super ovaries, suggesting a decisive role of CKs in controlling the timing of corolla opening. Furthermore, 194 out of 11,127 differentially expressed genes identified in pairwise comparisons, including critical developmental, signaling, and cytological regulators, contained all three types of cis-elements for CK, nitrate, and phosphorus responses in their promoter regions, indicating that the integration of hormone modulation and nutritional regulation orchestrated the precise control of corolla opening in cucumber. Our findings provide a valuable framework for dissecting the regulatory pathways for flower opening in plants.The flower is the most distinguishing organ in higher plants, and artists and scientists have been attracted to explore the mystery of flower structure and origin for decades. The evolution of flowering plants was greatly accelerated approximately 100 million years ago with the development of flowers, which were essential for recruiting animals to help distribute pollen and seeds (Danielson and Frommer, 2013). Flowers are produced from a specialized structure in the shoot tip called the shoot apical meristem, which consists of a pool of stem cells that continuously divide and replenish themselves (Fletcher et al., 1999). Morphologically, flowers are comprised of four basic structures arranged in concentric whorls: sepals in the outermost whorl 1, petals in whorl 2, stamens in whorl 3, and carpels in the innermost whorl 4. Bisexual flowers possess all four basic structures, while unisexual flowers lack one or more structures, usually the male organ stamen or the female organ carpel (Dellaporta and Calderon-Urrea, 1993). In flowering plants, approximately 90% species produce bisexual flowers, 6% species are dioecious with male and female flowers on separate plants, and 4% species a...
Background: Paclitaxel plays a pivotal role in the chemotherapy of breast cancer, but resistance to this drug is an important obstacle in the treatment. It is reported that microRNA-152-3p (miR-152-3p) is involved in tamoxifen resistance in breast cancer, but whether it is involved in paclitaxel resistance in breast cancer remains unknown. Materials and methods: We examined the expression of miR-152-3p in breast cancer tissues and cells by qRT-PCR. After transfecting paclitaxel-resistant MCF-7/TAX cells with miR-152-3p mimics, we analyzed the function of miR-152-3p in these cells by MTT assay and flow cytometry. We screened the target gene, endothelial PAS domain-containing protein 1 (EPAS1), using bioinformatics analysis and verified it with the dual luciferase reporter gene experiment. The relationship between EPAS1 and miR-152-3p and their roles in paclitaxel resistance of breast cancer were further investigated using RNA interference and transfection techniques. Results: The expression of miR-152-3p in normal breast tissues and cells was markedly higher than that in breast cancer. Overexpression of miR-152-3p decreased the survival rate and increased the apoptosis rate and sensitivity of MCF-7/TAX cells to paclitaxel. We confirmed that EPAS1 is the target of miR-152-3p and is negatively regulated by this miRNA. Moreover, transfection with EPAS1 siRNA enhanced the susceptibility and apoptosis rate of MCF-7/TAX cells to paclitaxel. Co-transfection of miR-152-3p mimics and EPAS1 increased paclitaxel sensitivity and apoptosis induced by the drug. Conclusion: miR-152-3p inhibits the survival of MCF-7/TAX cells and promotes their apoptosis by targeting the expression of EPAS1, thereby, enhancing the sensitivity of these breast cancer cells to paclitaxel.
To develop a molecular probe for MRI detection of human tumor telomerase reverse transcriptase (hTERT) mRNA expression. Uniformly phosphorothioate‐modified hTERT antisense oligonucleotide (ASON) homing hTERT mRNA was labeled with gadolinium (Gd) through the bifunctional chelator 1,4,7, 10‐tetraazacyclododecane‐N, N', N'', N'''‐tetraacetic acid (DOTA) stirred within 45 minutes at 60°C. The Gd labeled probes were characterized in vitro. The cellular uptake rate and biodistribution of 99mTc‐DOTA‐ASON was measured instead of that of Gd‐DOTA‐ASON. A549 lung adenocarcinoma model was established in BALB/c nude mice and Gd‐DOTA‐ASON was injected intraperitoneally and MR images were acquired using 7.0T Micro‐MRI (Bruker Biospec, Ettlingen, Germany) at different time points. Immunohistochemical analysis of telomerase activity of each xenograft was operated two days after in vivo imaging. The binding efficiency of Gd‐DOTA‐ASON reached as high as 71.7 ± 4.5% (n = 6). Gd‐DOTA‐ASON displayed perfect stability in fresh human serum at 37°C for 24 h. Compared with normal lung cells, A549 cells showed an obviously higher uptake of 99mTc‐DOTA‐ASON than that of lung cells (10.5 ± 2.7% vs. 4.8 ± 2.6%, P < 0.05). The signal intensity of A549 xenografts can be enhanced by Gd‐DOTA‐ASON and the signal to noise ratio (SNR) of tumor to muscle reached 2.37 and maintained a relatively high level within 6 h after injection. The activity of hTERT in A549 tumors can be suppressed by Gd‐DOTA‐ASON in pathological slices. The results of this study show that Gd‐DOTA‐ASON can be a promising intracellular MR contrast probe for targeting telomerase‐positive carcinomas. (Cancer Sci, doi: 10.1111/j.1349‐7006.2012.02316.x, 2012)
A549 cells transfected by ultrasound microbubble-mediated antisense miRNA-224 and miRNA-122a plasmids possessed good transfection efficiency. The cell growth, invasion and colony-forming abilities of transfected A549 cells were suppressed, which laid a solid foundation for the gene therapy of non-small cell lung cancer.
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