Extreme risk contagion from the United States to BRICS stock markets : a multivariate quantile analysis

This paper explores the transmission of risk from the United States equity market to the equity markets of the BRICS countries (Brazil, Russia, India, China, and South Africa) using a multivariate quantile process. The focus is on the contagion effect at the extreme quantiles, both upside and downside. In addition, a pseudo-impulse-response function (PIRF) analysis is conducted to investigate the responses of the five emerging stock markets to a shock in the US market. The results reveal an asymmetric pattern of underlying tail dependence from three different perspectives: the sign of the effect in response to external shocks at various quantiles, the extent and persistence of the effect, and a shift in dependency structure across different market phases. The paper also discusses the implications of these findings for investors and policymakers in terms of portfolio holdings and policy coordination

Analysing the impacts of unscheduled news events on stock market contagion during the epidemic

This paper investigates the impact of unscheduled news announcements on market contagion during the COVID-19 pandemic. Using co-exceedance of stock returns as a metric for market contagion effect, we assess the contribution of news releases from the US and China on the financial contagion of a representative group of global equity markets through a quantile analysis framework. The empirical results are mixed: news events originating in the US have a greater impact on market contagion compared to those originating in China, especially at lower quantiles. Stock markets respond asymmetrically to good news versus bad news, and the latter lead to a sharper common fall among the markets than the boost to the market caused by good news. We also find evidence that conditional variance and investor sentiment play some role in the spread of financial market crises, despite differences in extent and direction

Putative DHHC-Cysteine-Rich Domain S-Acyltransferase in Plants

Protein S-acyltransferases (PATs) containing Asp-His-His-Cys within a Cys-rich domain (DHHC-CRD) are polytopic transmembrane proteins that are found in eukaryotic cells and mediate the S-acylation of target proteins. S-acylation is an important secondary and reversible modification that regulates the membrane association, trafficking and function of target proteins. However, little is known about the characteristics of PATs in plants. Here, we identified 804 PATs from 31 species with complete genomes. The analysis of the phylogenetic relationships suggested that all of the PATs fell into 8 groups. In addition, we analysed the phylogeny, genomic organization, chromosome localisation and expression pattern of PATs in Arabidopsis, Oryza sative, Zea mays and Glycine max. The microarray data revealed that PATs genes were expressed in different tissues and during different life stages. The preferential expression of the ZmPATs in specific tissues and the response of Zea mays to treatments with phytohormones and abiotic stress demonstrated that the PATs play roles in plant growth and development as well as in stress responses. Our data provide a useful reference for the identification and functional analysis of the members of this protein family

Investigations into a putative role for the novel BRASSIKIN pseudokinases in compatible pollen-stigma interactions in Arabidopsis thaliana.

BACKGROUND: In the Brassicaceae, the early stages of compatible pollen-stigma interactions are tightly controlled with early checkpoints regulating pollen adhesion, hydration and germination, and pollen tube entry into the stigmatic surface. However, the early signalling events in the stigma which trigger these compatible interactions remain unknown. RESULTS: A set of stigma-expressed pseudokinase genes, termed BRASSIKINs (BKNs), were identified and found to be present in only core Brassicaceae genomes. In Arabidopsis thaliana Col-0, BKN1 displayed stigma-specific expression while the BKN2 gene was expressed in other tissues as well. CRISPR deletion mutations were generated for the two tandemly linked BKNs, and very mild hydration defects were observed for wild-type Col-0 pollen when placed on the bkn1/2 mutant stigmas. In further analyses, the predominant transcript for the stigma-specific BKN1 was found to have a premature stop codon in the Col-0 ecotype, but a survey of the 1001 Arabidopsis genomes uncovered three ecotypes that encoded a full-length BKN1 protein. Furthermore, phylogenetic analyses identified intact BKN1 orthologues in the closely related outcrossing Arabidopsis species, A. lyrata and A. halleri. Finally, the BKN pseudokinases were found to be plasma-membrane localized through the dual lipid modification of myristoylation and palmitoylation, and this localization would be consistent with a role in signaling complexes. CONCLUSION: In this study, we have characterized the novel Brassicaceae-specific family of BKN pseudokinase genes, and examined the function of BKN1 and BKN2 in the context of pollen-stigma interactions in A. thaliana Col-0. Additionally, premature stop codons were identified in the predicted stigma specific BKN1 gene in a number of the 1001 A. thaliana ecotype genomes, and this was in contrast to the out-crossing Arabidopsis species which carried intact copies of BKN1. Thus, understanding the function of BKN1 in other Brassicaceae species will be a key direction for future studies

Elevation of the Yields of Very Long Chain Polyunsaturated Fatty Acids via Minimal Codon Optimization of Two Key Biosynthetic Enzymes

Eicosapentaenoic acid (EPA, 20:5Δ5,8,11,14,17) and Docosahexaenoic acid (DHA, 22:6Δ4,7,10,13,16,19) are nutritionally beneficial to human health. Transgenic production of EPA and DHA in oilseed crops by transferring genes originating from lower eukaryotes, such as microalgae and fungi, has been attempted in recent years. However, the low yield of EPA and DHA produced in these transgenic crops is a major hurdle for the commercialization of these transgenics. Many factors can negatively affect transgene expression, leading to a low level of converted fatty acid products. Among these the codon bias between the transgene donor and the host crop is one of the major contributing factors. Therefore, we carried out codon optimization of a fatty acid delta-6 desaturase gene PinD6 from the fungus Phytophthora infestans, and a delta-9 elongase gene, IgASE1 from the microalga Isochrysis galbana for expression in Saccharomyces cerevisiae and Arabidopsis respectively. These are the two key genes encoding enzymes for driving the first catalytic steps in the Δ6 desaturation/ Δ6 elongation and the Δ9 elongation/Δ8 desaturation pathways for EPA/DHA biosynthesis. Hence expression levels of these two genes are important in determining the final yield of EPA/DHA. Via PCR-based mutagenesis we optimized the least preferred codons within the first 16 codons at their N-termini, as well as the most biased CGC codons (coding for arginine) within the entire sequences of both genes. An expression study showed that transgenic Arabidopsis plants harbouring the codon-optimized IgASE1 contained 64% more elongated fatty acid products than plants expressing the native IgASE1 sequence, whilst Saccharomyces cerevisiae expressing the codon optimized PinD6 yielded 20 times more desaturated products than yeast expressing wild-type (WT) PinD6. Thus the codon optimization strategy we developed here offers a simple, effective and low-cost alternative to whole gene synthesis for high expression of foreign genes in yeast and Arabidopsis

Identification of a rice metal tolerance protein OsMTP11 as a manganese transporter.

Metal tolerance proteins (MTPs) are a gene family of cation efflux transporters that occur widely in plants and might serve an essential role in metal homeostasis and tolerance. Our research describes the identification, characterization, and localization of OsMTP11, a member of the MTP family from rice. OsMTP11 was expressed constitutively and universally in different tissues in rice plant. Heterologous expression in yeast showed that OsMTP11 complemented the hypersensitivity of mutant strains to Mn, and also complemented yeast mutants to other metals, including Co and Ni. Real time RT-PCR analysis demonstrated OsMTP11 expression was substantially enhanced following 4 h under Cd, Zn, Ni, and Mn treatments, suggesting possible roles of OsMTP11 involvement in heavy metal stress responses. Promoter analysis by transgenic assays with GUS as a reporter gene and mRNA in situ hybridization experiments showed that OsMTP11 was expressed specifically in conducting tissues in rice. DNA methylation assays of genomic DNA in rice treated with Cd, Zn, Ni, and Mn revealed that decreased DNA methylation levels were present in the OsMTP11 promoter region, which was consistent with OsMTP11 induced-expression patterns resulting from heavy metal stress. This result suggested that DNA methylation is one of major factors regulating expression of OsMTP11 through epigenetic mechanisms. OsMTP11 fused to green fluorescent protein (GFP) localized to the entire onion epidermal cell cytoplasm, while vacuolar membrane exhibited increased GFP signals, consistent with an OsMTP11 function in cation sequestration. Our results indicated that OsMTP11 might play vital roles in Mn and other heavy metal transportation in rice

mRNA <i>in situ</i> hybridization of <i>OsMTP11</i> in rice leaves.

<p><i>Blue</i> or <i>purple</i> precipitates indicate positive <i>OsMTP11</i> mRNA signals. <b>A.</b> Transverse sections of a mature leaf. <b>B.</b> Transverse sections of a young leaf bud. <b>C.</b> Longitudinal sections of a seedling leaf bud. <b>D.</b> Control with the transverse sections of leaf bud.</p

Bioinformatics analyses of <i>OsMTP11</i> nucleotide and amino acid sequences.

<p><b>A.</b><i>OsMTP11</i> gene structure analysis in the Rice Genome Annotation Database (<a href="http://rice.plantbiology.msu.edu/" target="_blank">http://rice.plantbiology.msu.edu/</a>). <b>B.</b> Phylogenetic tree of the <i>MTP</i> family from rice and <i>Arabidopsis</i>. The tree was constructed using MEGA 4.0.2 by the neighbor-joining method. <i>Arabidopsis</i> MTP amino acid sequences were obtained from <a href="http://www.tigr.org" target="_blank">www.tigr.org</a>: AtMTP1, At2g46800; AtMTP2, At3g61940; AtMTP3, At3g58810; AtMTP4, At2g29410; AtMTP5, At3g12100; AtMTP6, At2g47830; AtMTP7, At1g51610; AtMTP8, At3g58060; AtMTP9, At1g79520; AtMTP10, At1g16310; AtMTP11, At2g39450; AtMTP12, At2g04620. Rice MTP amino acid sequences were downloaded from <a href="http://rice.plantbiology.msu.edu/" target="_blank">http://rice.plantbiology.msu.edu/</a>. OsMTP11, Os01g62070; OsMTP1, Os05g03780; OsMTP5, Os02g58580; OsMTP6, Os03g22550; OsMTP7, Os04g23180; OsMTP8, Os02g53490; OsMTP8.1, Os03g12580; OsMTP9, Os01g03914; OsMTP11, Os01g62070; OsMTP11.1, Os05g38670; OsMTP12, Os08g32680. <b>C.</b> Amino acid alignment of OsMTP11, AtMTP11 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref011" target="_blank">11</a>] and ShMTP1 (AY181256) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref012" target="_blank">12</a>]. Amino acid sequences of four predicted transmembrane (TM) segments are boxed. Amino acid residues with dark shading indicate conserved sequences, and residues with light gray shading indicate those conserved in two protein sequences. <b>D.</b> The predicted transmembrane helices of OsMTP11. The transmembrane domains were estimated using TMHMM2: <a href="http://www.cbs.dtu.dk/services/TMHMM/" target="_blank">www.cbs.dtu.dk/services/TMHMM/</a>. The peaks show the predicted transmembrane (TM) regions of proteins. These data indicate that OsMTP11 has four obvious TM regions.</p

The <i>OsMTP11</i> putative promoter region (-2,250 bp) sequence.

<p>The transcription start site is denoted +1, and the putative start codon is underlined. Diagram of the <i>OsMTP11</i> promoter region using PlantCARE (<a href="http://bioinformatics.psb.ugent.be/webtools/plantcare/html/" target="_blank">http://bioinformatics.psb.ugent.be/webtools/plantcare/html/</a>) showed the presence of a number of potential cis-acting elements that respond to environmental signals. MRE, metal-response element [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref034" target="_blank">34</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref035" target="_blank">35</a>]; ABRE, abscisic acid-response element [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref036" target="_blank">36</a>]; I-box, light-response element [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref037" target="_blank">37</a>]; BS1EGCCR, "BS1 (binding site 1)" found in CCR gene promoter, which is a cis-element required for vascular expression of the cinnamoyl CoA reductase gene in <i>E</i>. <i>gunnii</i> [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref038" target="_blank">38</a>]. MREs include MRE1: 5’-TGCRCNC-3’ (R = A or G; N = any residue) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref034" target="_blank">34</a>] and MRE2: 5’-HTHNNGCTGD-3’ (D = A, G, or T; H = A, C, or T; N = any residue) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0174987#pone.0174987.ref035" target="_blank">35</a>].</p

Expression pattern of <i>OsMTP11</i> by real time RT-PCR.

<p><b>A.</b> Real time RT-PCR results of <i>OsMTP11</i> expression in wild-type rice plants (Nipponbare) from different tissues or organs. The amplification of the rice <i>OsUBQ5</i> (AK061988) gene was used as a control to normalize the transcript level of <i>OsMTP11</i>. <b>B.</b> Expression analysis of <i>OsMTP11</i> under different heavy metal stresses (Mn, Cd, Zn and Ni) by real time RT-PCR. The expression of <i>OsMTP11</i> is increased in rice roots and shoots treated with 0.5 mM CdCl₂, 5 mM Zn(NO₃)₂, 1 mM NiCl₂, 2 mM MnSO₄, 300 mM NaCl and 100 μM methyl viologen (MV) for different time periods. <b>C.</b> Expression analysis of <i>OsMTP11</i> under 300 mM NaCl and 100 μM methylviologen (MV) by real time RT-PCR.</p