New Insights into the Organization, Recombination, Expression and Functional Mechanism of Low Molecular Weight Glutenin Subunit Genes in Bread Wheat

The bread-making quality of wheat is strongly influenced by multiple low molecular weight glutenin subunit (LMW-GS) proteins expressed in the seeds. However, the organization, recombination and expression of LMW-GS genes and their functional mechanism in bread-making are not well understood. Here we report a systematic molecular analysis of LMW-GS genes located at the orthologous Glu-3 loci (Glu-A3, B3 and D3) of bread wheat using complementary approaches (genome wide characterization of gene members, expression profiling, proteomic analysis). Fourteen unique LMW-GS genes were identified for Xiaoyan 54 (with superior bread-making quality). Molecular mapping and recombination analyses revealed that the three Glu-3 loci of Xiaoyan 54 harbored dissimilar numbers of LMW-GS genes and covered different genetic distances. The number of expressed LMW-GS in the seeds was higher in Xiaoyan 54 than in Jing 411 (with relatively poor bread-making quality). This correlated with the finding of higher numbers of active LMW-GS genes at the A3 and D3 loci in Xiaoyan 54. Association analysis using recombinant inbred lines suggested that positive interactions, conferred by genetic combinations of the Glu-3 locus alleles with more numerous active LMW-GS genes, were generally important for the recombinant progenies to attain high Zeleny sedimentation value (ZSV), an important indicator of bread-making quality. A higher number of active LMW-GS genes tended to lead to a more elevated ZSV, although this tendency was influenced by genetic background. This work provides substantial new insights into the genomic organization and expression of LMW-GS genes, and molecular genetic evidence suggesting that these genes contribute quantitatively to bread-making quality in hexaploid wheat. Our analysis also indicates that selection for high numbers of active LMW-GS genes can be used for improvement of bread-making quality in wheat breeding

Research on the Spatial Network Effect of Urban Tourism Flows from Shanghai Disneyland

For a long time, Shanghai’s urban tourism has presented a single-core agglomeration pattern with the Bund area as the core, with the phenomenon of overcrowding in the core area during holidays. The opening of Disneyland in 2016 has had an important impact on the development of Shanghai’s urban tourism, including the spatial network of tourism flows. This study selects the travel notes of domestic tourists to Shanghai from Ctrip.com and sorts out a total of 1419 pieces of valid spatial information before and after the opening of Disneyland. With the help of social network analysis, it analyses the influence of Disneyland on the spatial network of domestic tourism flows in Shanghai. The results show that Disneyland has become a new spatial growth pole of Shanghai urban tourism, with an obvious network nuclear Overhauser effect, which is conducive to alleviating congestion in the Bund area, but the correlation effect of Disneyland on other tourism nodes is not obvious. The connection between high-grade tourism nodes is further enhanced, and some low-grade tourism nodes are more marginalized, showing the Matthew effect of nodes and the combined effects of nodes. Accordingly, this paper puts forward three suggestions. First, to strengthen the optimal design of tourism routes and enhance the connection between Disneyland and other tourism nodes; second, to upgrade low-grade tourism nodes, enhance recognition and strengthen integration with core tourism nodes; and, third, to strengthen top-level planning, provide comprehensive support for Disneyland, enhance its industrial linkage effect and spatial network effect, and promote the sustainable development of Shanghai’s urban tourism

Precarious job makes me withdraw? The role of job insecurity and negative affect

An expanding “gig” economy has changed the nature of employment; thus, researchers have recently focused on exploring the role of job precariousness in the workplace. However, little research attention has been given to understanding why, how and when job precariousness leads to employees’ negative behavioral outcomes in the service-oriented industry. In the current study, we examined job insecurity as a mediator and employees’ negative affect as a moderator in the relationship between job precariousness and employees’ withdrawal behavior. Using a sample of 472 employees working in Chinese hotels, we found that job precariousness is positively related to employees’ withdrawal behavior by increasing their job insecurity. Moreover, this mediating relationship is conditional on the moderator variable of employees’ negative affect for the path from job insecurity to withdrawal behavior. The importance of these findings for understanding the un-desirable behavior outcomes of job precariousness is discussed

Identification and characterization of high-molecular-weight glutenin subunits from Agropyron intermedium.

High-molecular-weight glutenin subunit (HMW-GS) is a primary determinant of processing quality of wheat. Considerable progress has been made in understanding the structure, function and genetic regulation of HMW-GS in wheat and some of its related species, but less is known about their orthologs in Agropyron intermedium, a useful related species for wheat improvement. Here seven HMW-GSs in Ag. intermedium were identified using SDS-PAGE and Western blotting experiments. Subsequently, the seven genes (Glu-1Aix1 ∼ 4 and Glu-1Aiy1 ∼ 3) encoding the seven HMW-GSs were isolated using PCR technique with degenerate primers, and confirmed by bacterial expression and Western blotting. Sequence analysis indicated that the seven Ag. intermedium HMW-GSs shared high similarity in primary structure to those of wheat, but four of the seven subunits were unusually small compared to the representatives of HMW-GS from wheat and two of them possessed extra cysteine residues. The alignment and clustering analysis of deduced amino acid sequences revealed that 1Aix1 and 1Aiy1 subunits had special molecular structure, belonging to the hybrid type compounding between typical x- and y-type subunit. The xy-type subunit 1Aix1 is composed of the N-terminal of x-type and C-terminal of y-type, whereas yx-type subunit 1Aiy1 comprises the N-terminal of y-type and C-terminal of x-type. This result strongly supported the hypothesis of unequal crossover mechanism that might generate the novel coding sequence for the hybrid type of HMW-GSs. In addition to the aforementioned, the other novel characteristics of the seven subunits were also discussed. Finally, phylogenetic analysis based on HMW-GS genes was carried out and provided new insights into the evolutionary biology of Ag. intermedium

Illustration for the developmental mechanism of two hybrid HMW-GSs based on unequal double crossover hypothesis.

<p>The broken line box indicates the double crossover region. The xy and yx represent the hybrid subunit with 5′region of x-type and 3′region of y-type and the hybrid subunit with 5′region of y-type and 3′region of x-type, respectively.</p

Properties of the primary structure of the HMW-GS from <i>Ag. intermedium</i> in comparison with those of the representatives of wheat HMW-GS.

a<p>The nucleotide number of Open Reading Frame;</p>b<p>The number of Cys.</p

SDS-PAGE (A) and Western blotting (B) analysis of HMW-GSs from <i>Ag. intermedium</i> and bacterial expression products.

<p>Lane 1 is HMW-GSs from common wheat variety Chinese Spring, the four expressed HMW-GSs are noted on left; Lane 2 is native HMW-GS from the seed of <i>Ag. intermedium</i> same as the lane 2 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087477#pone-0087477-g001" target="_blank">Figure 1</a>, the seven expressed HMW-GSs are marked with triangles; Lane 3, 5, 7, 9, 11, 13 and 15 are total cell proteins from IPTG induced <i>E. coli</i> containing pET-<i>Glu-1Ai1</i>, pET-<i>Glu-1Ai2</i>, pET-<i>Glu-1Ai3</i>, pET-<i>Glu-1Ai4</i>, pET-<i>Glu-1Ai5</i> pET-<i>Glu-1Ai6</i> and pET-<i>Glu-1Ai7</i>, respectively, whereas the dextral lanes for each of them shows the total cell proteins from their bacterial cells without induction of IPTG. The seven expressed target proteins in <i>E. coli</i>, which were detected by SDS-PAGE (marked with arrows in A) and were confirmed by Western blotting (lanes 3, 5, 7, 9, 11, 13 and 15 in B), share comparable electrophoretic mobility with those native HMW-GSs from <i>Ag. intermedium</i> (lane 2).</p

MALDI-TOF-MS analysis of peptide mass fingerprint of native 1Aiy1 subunit.

<p>Peptide mass is available at <a href="http://www.expasy.org/tools/peptide-mass.html" target="_blank">http://www.expasy.org/tools/peptide-mass.html</a>.</p

Phylogenetic tree of <i>Thinopyrum intermedium</i> ( = <i>Ag. intermedium</i>) and some representative HMW-GSs from <i>Triticeae</i>.

<p>This phylogenetic tree was constructed with Maximum Likelihood Estimation method based on the nucleotide sequences encoding signal peptide and N-terminal conserved region of HMW-GSs plus the next three repeat units, one dodecapeptide, one undecapeptide and one hexapeptide repeat. D-hordein from barley was used as outgroup. The species names of HMW-GS genes in this figure are consistent with their accession names in GenBank, so here we replaced <i>Agropyron intermedium</i> with <i>Thinopyrum intermedium</i>.</p