Overexpression of BplERD15 enhances drought tolerance in Betula platyphylla Suk

In this study, we report the cloning and functional characterization of an early responsive gene, BplERD15, from Betula platyphylla Suk to dehydration. BplERD15 is located in the same branch as Morus indica Linnaeus ERD15 and Arabidopsis Heynh ERD15 in the phylogenetic tree built with ERD family protein sequences. The tissue-specific expression patterns of BplERD15 were characterized using qRT-PCR and the results showed that the transcript levels of BplERD15 in six tissues were ranked from the highest to the lowest levels as the following: mature leaves (ML) \u3e young leaves (YL) \u3e roots (R) \u3ebuds (B) \u3eyoung stems (YS) \u3emature stems (MS). Multiple drought experiments were simulated by adding various osmotica including polyethylene glycol, mannitol, and NaCl to the growth media to decrease their water potentials, and the results showed that the expression of BplERD15 could be induced to 12, 9, and 10 folds, respectively, within a 48 h period. However, the expression level of BplERD15 was inhibited by the plant hormone abscisic acid in the early response and then restored to the level of control. The BplERD15 overexpression (OE) transgenic birch lines were developed and they did not exhibit any phenotypic anomalies and growth deficiency under normal condition. Under drought condition, BplERD15-OE1, 3, and 4 all displayed some drought tolerant characteristics and survived from the drought while the wild type (WT) plants withered and then died. Analysis showed that all BplERD15-OE lines had significant lower electrolyte leakage levels as compared to WT. Our study suggests that BplERD15 is a drought-responsive gene that can reduce mortality under stress condition

A systems biology approach identifies a regulator, BplERF1, of cold tolerance in Betula platyphylla

Cold is an abiotic stress that can greatly affect the growth and survival of plants. Here, we reported that an AP2/ERF family gene, BplERF1, isolated from Betula platyphylla played a contributing role in cold stress tolerance. Overexpression of BplERF1 in B. platyphylla transgenic lines enhanced cold stress tolerance by increasing the scavenging capability and reducing H2O2 and malondialdehyde (MDA) content in transgenic plants. Construction of BplERF-mediated multilayered hierarchical gene regulatory network (ML-hGRN), using Top-down GGM algorithm and the transcriptomic data of BplERF1 overexpression lines, led to the identification of five candidate target genes of BplERF1 which include MPK20, ERF9, WRKY53, WRKY70, and GIA1. All of them were then verified to be the true target genes of BplERF1 by chromatin-immunoprecipitation PCR (ChIP-PCR) assay. Our results indicate that BplERF1 is a positive regulator of cold tolerance and is capable of exerting regulation on the expression of cold signaling and regulatory genes, causing mitigation of reactive oxygen species

Growth-regulating factor 5 (GRF5)-mediated gene regulatory network promotes leaf growth and expansion in poplar

Although polyploid plants have larger leaves than their diploid counterparts, the molecular mechanisms underlying this difference (or trait) remain elusive. Differentially expressed genes (DEGs) between triploid and full-sib diploid poplar trees were identified from two transcriptomic data sets followed by a gene association study among DEGs to identify key leaf growth regulators. Yeast one-hybrid system, electrophoretic mobility shift assay, and dual-luciferase assay were employed to substantiate that PpnGRF5-1 directly regulated PpnCKX1. The interactions between PpnGRF5-1 and growth-regulating factor (GRF)-interacting factors (GIFs) were experimentally validated and a multilayered hierarchical regulatory network (ML-hGRN)-mediated by PpnGRF5-1 was constructed with top-down graphic Gaussian model (GGM) algorithm by combining RNA-sequencing data from its overexpression lines and DAP-sequencing data. PpnGRF5-1 is a negative regulator of PpnCKX1. Overexpression of PpnGRF5-1 in diploid transgenic lines resulted in larger leaves resembling those of triploids, and significantly increased zeatin and isopentenyladenine in the apical buds and third leaves. PpnGRF5-1 also interacted with GIFs to increase its regulatory diversity and capacity. An ML-hGRN-mediated by PpnGRF5-1 was obtained and could largely elucidate larger leaves. PpnGRF5-1 and the ML-hGRN-mediated by PpnGRF5-1 were underlying the leaf growth and development

Design and Verification of a Novel Triphibian Robot

Multi-modal robots expand their operations from one working medium to another, land to air for example. The majorities of multi-modal robots mainly refer to platforms that operate in two different media. However, for all-terrain tasks, there are seldom research to date in the literature. Generally, locomotions in different working media, i.e. land, water and air, require different propelling actuators, and thus the triphibian system becomes bulky. To overcome this challenge, we proposed a triphibian robot and provide the robot with driving forces to perform all-terrain operations in an efficient way. A morphable mechanism is designed to enable the transition between different motion modes, and specifically a cylindrical body is implemented as the rolling mechanism in land mode. Detailed design principles of different mechanisms and the transition between various locomotion modes are analyzed. Finally, a triphibian robot prototype is fabricated and tested in various working media with both mono-modal and multi-modal functionalities. Experiments have verified our platform, and the results show promising adaptions in future exploration tasks in various working scenarios.Comment: IEEE ROBOTICS AND AUTOMATION LETTERS. PREPRINT VERSION,8 page

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

A R2R3-MYB Transcription Factor Gene, BpMYB123, Regulates BpLEA14 to Improve Drought Tolerance in Betula platyphylla

Drought stress causes various negative impacts on plant growth and crop production. R2R3-MYB transcription factors (TFs) play crucial roles in the response to abiotic stress. However, their functions in Betula platyphylla haven’t been fully investigated. In this study, a R2R3 MYB transcription factor gene, BpMYB123, was identified from Betula platyphylla and reveals its significant role in drought stress. Overexpression of BpMYB123 enhances tolerance to drought stress in contrast to repression of BpMYB123 by RNA interference (RNAi) in transgenic experiment. The overexpression lines increased peroxidase (POD) and superoxide dismatase (SOD) activities, while decreased hydrogen peroxide (H2O2), superoxide radicals (O2–), electrolyte leakage (EL) and malondialdehyde (MDA) contents. Our study showed that overexpression of BpMYB123 increased BpLEA14 gene expression up to 20-fold due to BpMYB123 directly binding to the MYB1AT element of BpLEA14 promoter. These results indicate that BpMYB123 acts as a regulator via regulating BpLEA14 to improve drought tolerance in birch

Overexpression of an AP2/ERF family gene, BpERF13, in birch enhances cold tolerance through upregulating CBF genes and mitigating reactive oxygen species.

The AP2/ERF (APETALA2/ethylene-responsive factor) family of transcription factors (TF) is involved in regulating biotic and abiotic stress responses in plants. To explore the role of AP2/ERFs in cold tolerance in woody plants, BpERF13 was cloned and characterized in Betula platyphylla (white birch), a species primarily found in Asia in temperate and boreal climates. Based on phylogenetic analysis, BpERF13 is a member of the IXb subfamily of ERFs. Using qRT-PCR, we found that BpERF13 was differentially expressed in different tissues, and its expression could be induced by cold treatment (4 °C). BpERF13 protein, fused with GFP, was exclusively localized to nuclei. To further assess the role of BpERF13 in cold tolerance, BpERF13 overexpression (OE) transgenic lines were generated in B. platyphylla and used for cold stress treatment and biochemical/physiological studies. BpERF13 overexpression lines had significantly increased tolerance to subfreezing treatment and reduced reactive oxygen species. Using a TF-centered yeast one-hybrid (Y1H) experimental system, we showed that BpERF13 could bind to LTRECOREATCOR15 and MYBCORE cis-elements to activate a reporter gene. ChIP-seq and ChIP-PCR experiments further demonstrated that BpERF13 bound to these cis-elements when present in the 5\u27 proximal regions of superoxide dismutase (SOD), peroxidase (POD), and C-repeat-binding factor (CBF) genes. qRT-PCR was employed to examine the expression levels of these genes in response to cold stress; SOD, POD, and CBF genes were significantly upregulated in BpERF13 transgenic lines compared to wild-type plants in response to cold stress. These results indicate that the transcription factor BpERF13 regulates physiological processes underlying cold tolerance in woody plants

Directional Bloch surface wave coupling enabled by magnetic spin-momentum locking of light

International audience<span id="top"&gtWe study the magnetic spin-locking of opticalsurface waves. Through an angular spectrum approach and numericalsimulations, we predict that a spinning magnetic dipole develops adirectional coupling of light to transverse electric (TE) polarizedBloch surface waves (BSWs). A high-index nanoparticle as a magneticdipole and nano-coupler is placed on top of a one-dimensionalphotonic crystal to couple light into BSWs. Upon circularlypolarized illumination, it mimics the spinning magnetic dipole. Wefind that the helicity of the light impinging on the nano-couplercontrols the directionality of emerging BSWs. Furthermore,identical silicon strip waveguides are configured on the two sidesof the nano-coupler to confine and guide the BSWs. We achieve adirectional nano-routing of BSWs with circularly polarizedillumination. Such a directional coupling phenomenon is proved tobe solely mediated by the optical magnetic field. This offersopportunities for directional switching and polarization sorting bycontrolling optical flows in ultra-compact architectures andenables the investigation of the magnetic polarization propertiesof light.</span&g

The suppressive role and aberrent promoter methylation of BTG3 in the progression of hepatocellular carcinoma.

BACKGROUND:BTG3 (B-cell translocation gene 3) has been identified as a tumor suppressor and hypermethylation contributes to its down-regulation in some tumors, but its role in hepatocellular carcinoma (HCC) remain unknown. This study aimed to detect the expression and methylation status of BTG3 in HCC cell lines or tissues, and determine its function in HCC progression. METHODOLOGY:The expression of BTG3 was detected in HCC cell lines and HCC tissue by real-time RT-PCR, Western blot or immunohistochemistry. The promoter methylation status of BTG3 was measured by using methylation-specific PCR in HCC cell lines. A series of assays were performed to evaluate the effect of BTG3 on proliferation, invasion and cell cycle transition in vitro. RESULTS:BTG3 expression was lower in HCC cell lines than in hepatocyte cell line LO2 (P<0.05). BTG3 was also down-regulated in HCC tissues. Its expression was positively correlated with differentiation and distant metastasis (P<0.05). Patients with lower BTG3 expression had shorter overall survival time (P=0.029). DNA methylation directed repression of BTG3 mRNA expression in HCC cell lines. BTG3 suppressed proliferation, invasion and induces G1/S cycle arrest of HCC cells in vitro. CONCLUSION:Down-regulation of BTG3 due to the promoter hypermethylation is closely associated with proliferation, invasion and cell cycle arrest of HCC cells. It may be a novel prognostic biomarker for HCC patients

Automatic localization and identification of mitochondria in cellular electron cryo-tomography using faster-RCNN

Abstract Background Cryo-electron tomography (cryo-ET) enables the 3D visualization of cellular organization in near-native state which plays important roles in the field of structural cell biology. However, due to the low signal-to-noise ratio (SNR), large volume and high content complexity within cells, it remains difficult and time-consuming to localize and identify different components in cellular cryo-ET. To automatically localize and recognize in situ cellular structures of interest captured by cryo-ET, we proposed a simple yet effective automatic image analysis approach based on Faster-RCNN. Results Our experimental results were validated using in situ cyro-ET-imaged mitochondria data. Our experimental results show that our algorithm can accurately localize and identify important cellular structures on both the 2D tilt images and the reconstructed 2D slices of cryo-ET. When ran on the mitochondria cryo-ET dataset, our algorithm achieved Average Precision >0.95. Moreover, our study demonstrated that our customized pre-processing steps can further improve the robustness of our model performance. Conclusions In this paper, we proposed an automatic Cryo-ET image analysis algorithm for localization and identification of different structure of interest in cells, which is the first Faster-RCNN based method for localizing an cellular organelle in Cryo-ET images and demonstrated the high accuracy and robustness of detection and classification tasks of intracellular mitochondria. Furthermore, our approach can be easily applied to detection tasks of other cellular structures as well