Analysis of signal output by the ethylene receptor ETR1 from Arabidopsis

Ethylene is one of the most important plant hormones and regulates many processes during plant growth and development. In Arabidopsis, the ethylene receptor family consists of five members: ETR1 and ERS1 have a functional histidine kinase domain and form subfamily 1; members of subfamily 2, including ETR2, ERS2, and EIN4, possess a highly diverged histidine kinase domain predicted not to be functional. To analyze signal output by the ethylene receptor ETR1 from Arabidopsis, mutant-based approaches were taken. Initially, the role of the proposed signal output region of ETR1 in ethylene signaling was examined. For this purpose, the ability of mutant versions of ETR1 to rescue the constitutive response phenotype of the etr1--6;etr2--3;ein4--4 triple loss-of-function mutant line was examined. A truncated version of ETR1 that lacks both the histidine kinase domain and the receiver domain failed to rescue the triple mutant phenotype. A truncated ETR1 receptor that lacks only the receiver domain restored normal growth to the triple mutant in air, but the transgenic seedlings displayed hypersensitivity to ethylene. A mutation that eliminated histidine kinase activity had a modest effect upon the ability of the receptor to repress ethylene responses in air. These results demonstrate that the histidine kinase domain is required for the repression of ethylene responses. To further address whether histidine kinase activity is required for ethylene signaling, single loss-of-function allele of ERS1 was isolated and ers1;etr1 double null mutants were generated. The ers1;etr1 double mutants displayed a constitutive ethylene response phenotype when grown in the dark, and were dwarfed with small and epinastic leaves in the air and died without bolting when grown under light. The phenotype of ers1;etr1 is more profound than that observed in the etr2--3;ein4--4;ers2--3 triple loss-of-function mutant reported previously, indicating that subfamily 1 members (ETR1 and ERS1) play a predominant role in ethylene signaling. Addition of the kinase-inactivated ETR1(G2) into a background containing both ers1--3 and etr1--7 mutations results in ethylene insensitivity, demonstrating that the histidine kinase activity of ETR1 may play a role in the establishment of ethylene responses

A strong constitutive ethylene-response phenotype conferred on Arabidopsis plants containing null mutations in the ethylene receptors ETR1 and ERS1

Background: The ethylene receptor family of Arabidopsis consists of five members, falling into two subfamilies. Subfamily 1 is composed of ETR1 and ERS1, and subfamily 2 is composed of ETR2, ERS2, and EIN4. Although mutations have been isolated in the genes encoding all five family members, the only previous insertion allele of ERS1 (ers1-2) is a partial loss-of-function mutation based on our analysis. The purpose of this study was to determine the extent of signaling mediated by subfamily-1 ethylene receptors through isolation and characterization of null mutations. Results: We isolated new T-DNA insertion alleles of subfamily 1 members ERS1 and ETR1 (ers1-3 and etr1-9, respectively), both of which are null mutations based on molecular, biochemical, and genetic analyses. Single mutants show an ethylene response similar to wild type, although both mutants are slightly hypersensitive to ethylene. Double mutants of ers1-3 with etr1-9, as well as with the previously isolated etr1-7, display a constitutive ethylene-response phenotype more pronounced than that observed with any previously characterized combination of ethylene receptor mutations. Dark-grown etr1-9;ers1-3 and etr1-7;ers1-3 seedlings display a constitutive triple-response phenotype. Light-grown etr1-9;ers1-3 and etr1-7;ers1-3 plants are dwarfed, largely sterile, exhibit premature leaf senescence, and develop novel filamentous structures at the base of the flower. A reduced level of ethylene response was still uncovered in the double mutants, indicating that subfamily 2 receptors can independently contribute to signaling, with evidence suggesting that this is due to their interaction with the Raf-like kinase CTR1. Conclusion: Our results are consistent with the ethylene receptors acting as redundant negative regulators of ethylene signaling, but with subfamily 1 receptors playing the predominant role. Loss of a single member of subfamily 1 is largely compensated for by the activity of the other member, but loss of both subfamily members results in a strong constitutive ethylene-response phenotype. The role of subfamily 1 members is greater than previously suspected and analysis of the double mutant null for both ETR1 and ERS1 uncovers novel roles for the receptors not previously characterized

An Attention-based Collaboration Framework for Multi-View Network Representation Learning

Learning distributed node representations in networks has been attracting increasing attention recently due to its effectiveness in a variety of applications. Existing approaches usually study networks with a single type of proximity between nodes, which defines a single view of a network. However, in reality there usually exists multiple types of proximities between nodes, yielding networks with multiple views. This paper studies learning node representations for networks with multiple views, which aims to infer robust node representations across different views. We propose a multi-view representation learning approach, which promotes the collaboration of different views and lets them vote for the robust representations. During the voting process, an attention mechanism is introduced, which enables each node to focus on the most informative views. Experimental results on real-world networks show that the proposed approach outperforms existing state-of-the-art approaches for network representation learning with a single view and other competitive approaches with multiple views.Comment: CIKM 201

4,4′-(Propane-1,3-di­yl)dipyridinium tetra­chloridonickelate(II)

The title compound, (C13H16N2)[NiCl4] or (H2bpp)·NiCl4 [bpp is 1,3-bis­(4-pyrid­yl)propane], is isostructural with its already reported Cu, Zn and Hg analogues. The structure consists of a doubly charged (H2bpp)2+ cation and a tetra­hedral [NiCl4]2− dianion. Both pyridyl N atoms are protonated and form a (H2bpp)2+ cation which adopts an anti–anti conformation with a dihedral angle of 6.287 (7)° between the pyridyl rings. The two pyridyl N atoms are both involved in strong N—H⋯Cl hydrogen bonds, which link both units into a dimer

A Neoclassic Growth Model of Leisure Time and China\u27s Economic Growth

The Purpose of this study was to assess the effect of leisure time on China’s long-run economic growth. Two compensation effects of leisure were introduced into the economic growth model to assess if leisure choice-set affect economic growth in the long-run. A time series data of 23 years (1981-2003) was used in the study. A neoclassic growth model was used to analyze the data. The result found a weak negative relationship between leisure time and China’s long-run economic growth

Exploring the Design Space of Immersive Urban Analytics

Recent years have witnessed the rapid development and wide adoption of immersive head-mounted devices, such as HTC VIVE, Oculus Rift, and Microsoft HoloLens. These immersive devices have the potential to significantly extend the methodology of urban visual analytics by providing critical 3D context information and creating a sense of presence. In this paper, we propose an theoretical model to characterize the visualizations in immersive urban analytics. Further more, based on our comprehensive and concise model, we contribute a typology of combination methods of 2D and 3D visualizations that distinguish between linked views, embedded views, and mixed views. We also propose a supporting guideline to assist users in selecting a proper view under certain circumstances by considering visual geometry and spatial distribution of the 2D and 3D visualizations. Finally, based on existing works, possible future research opportunities are explored and discussed.Comment: 23 pages,11 figure

Ceria–terbia solid solution nanobelts with high catalytic activities for CO oxidation

Ceria–terbia solid solution nanobelts were prepared by an electrochemical route and tested as catalysts of high activity for CO oxidation