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PIEZO1 is a non-selective cation channel protein that converts mechanical stimuli into electrochemical signals through mechanical force transmission. In recent years, more and more attention has been paid to its relationship with cardiovascular development and related diseases. However, PIEZO1 is difficult to be used as a therapeutic target due to incomplete study of its related phenotype and mechanism. Starting with the phenotypes of zebrafish at different stages of development, piezo1 knockout zebrafish features decreased heart rate in embryonic stage, increased heart size in 72dpf larvae, as well as ventricular enlargement, passivation and increased immune infiltration in adult stage. Further characterization revealed the relationship between PIEZO1 and AcanA protein at embryonic stage, and hand2 protein at adult stage. Through further RNA-seq analysis, ptpn21 downregulation, shox2 upregulation, itga4 upregulation were used to explain ventricular enlargement, heart rate decrease and immune infiltration increase respectively. Overall, this study provides a theoretical basis for elucidating the mechanism of PIEZO1 in regulating cardiac development.

The different genome-wide distributions of tri-methylation at H3K36 (H3K36me3) in various species suggest diverse mechanisms for H3K36me3 establishment during evolution. Here, we show that the transcription factor OsSUF4 recognizes a specific 7-bp DNA element, broadly distributes throughout the rice genome, and recruits the H3K36 methyltransferase SDG725 to target a set of genes including the key florigen genes RFT1 and Hd3a to promote flowering in rice. Biochemical and structural analyses indicate that several positive residues within the zinc finger domain are vital for OsSUF4 function in planta. Our results reveal a regulatory mechanism contributing to H3K36me3 distribution in plants., The distribution of H3K36me3 varies between species. Here Liu et al. show that the OsSUF4 transcription factor binds its target motif via a zinc finger domain to promote H3K36 methyltransferase targeting close to the transcription start site of genes including the flowering regulators RFT1 and Hd3a.

Lysozymes are known as ubiquitously distributed immune effectors with hydrolytic activity against peptidoglycan, the major bacterial cell wall polymer, to trigger cell lysis. In the present study, the full-length cDNA sequence of a novel sea urchin Strongylocentrotus purpuratus invertebrate-type lysozyme (sp-iLys) was synthesized according to the codon usage bias of Pichia pastoris and was cloned into a constitutive expression plasmid pPIC9K. The resulting plasmid, pPIC9K-sp-iLys, was integrated into the genome of P. pastoris strain GS115. The bioactive recombinant sp-iLys was successfully secreted into the culture broth by positive transformants. The highest lytic activity of 960 U/mL of culture supernatant was reached in fed-batch fermentation. Using chitin affinity chromatography and gel-filtration chromatography, recombinant sp-iLys was produced with a yield of 94.5 mg/L and purity of > 99%. Recombinant sp-iLys reached its peak lytic activity of 8560 U/mg at pH 6.0 and 30 °C and showed antimicrobial activities against Gram-negative bacteria (Vibrio vulnificus, Vibrio parahemolyticus, and Aeromonas hydrophila) and Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis). In addition, recombinant sp-iLys displayed isopeptidase activity which reached the peak at pH 7.5 and 37 °C with the presence of 0.05 M Na+. In conclusion, this report describes the heterologous expression of recombinant sp-iLys in P. pastoris on a preparative-scale, which possesses lytic activity and isopeptidase activity. This suggests that sp-iLys might play an important role in the innate immunity of S. purpuratus.

Exploration of the catalytic activity of low-dimensional transition metal (TM) or noble metal catalysts is a vital subject of modern materials science because of their instrumental role in numerous industrial applications. Recent experimental advances have demonstrated the utilization of single atoms on different substrates as effective catalysts, which exhibit amazing catalytic properties such as more efficient catalytic performance and higher selectivity in chemical reactions as compared to their nanostructured counterparts; however, the underlying microscopic mechanisms operative in these single atom catalysts still remain elusive. Based on first-principles calculations, herein, we present a comparative study of the key kinetic rate processes involved in CO oxidation using a monomer or dimer of two representative TMs (Pd and Ni) on defective TiO2(110) substrates (TMn@TiO2(110), n = 1, 2) to elucidate the underlying mechanism of single-atom catalysis. We reveal that the O2 activation rates of the single atom TM catalysts deposited on TiO2(110) are governed cooperatively by the classic spin-selection rule and the well-known frontier orbital theory (or generalized d-band picture) that emphasizes the energy gap between the frontier orbitals of the TM catalysts and O2 molecule. We further illuminate that the subsequent CO oxidation reactions proceed via the Langmuir–Hinshelwood mechanism with contrasting reaction barriers for the Pd monomer and dimer catalysts. These findings not only provide an explanation for existing observations of distinctly different catalytic activities of Pd@TiO2(110) and Pd2@TiO2(110) [Kaden et al., Science, 2009, 326, 826–829] but also shed new insights into future utilization and optimization of single-atom catalysis.

A full-length cDNA clone of OsFAD2, which encodes a Δ-12 fatty acid desaturase, the key enzyme for the conversion of oleic acid (18:1) into linoleic acid (18:2), was isolated from rice (Oryza sativa ssp. japonica) leaves. The deduced amino acid sequence of OsFAD2 displayed three histidine boxes characteristic of all membrane-bound desaturases, and possessed a C-terminal signal for endoplasmic reticulum retention. Phylogenetic analysis showed that OsFAD2 is grouped within plant housekeeping FAD2 sequences. Expression analysis by real-time PCR showed that the gene is expressed in all tissues of rice tested, including root, seed, stem, and leaf. In situ hybridization showed that OsFAD2 mRNA accumulated in leaf mesophyll cells and in root epidermis cells when exposed to 15°C for 4 days in dark conditions. When OsFAD2 was expressed in Saccharomyces cerevisiae, the cells could convert oleic acid to linoleic acid, which wild-type yeast cells cannot do, suggesting that the isolated gene encoded a functional FAD2 enzyme. Heterologous expression of OsFAD2 enhanced the yeast cells’ cold tolerance capacity compared to wild-type yeast. OsFAD2 was also shown to be a highly active desaturase when expressed in Xenopus oocytes. In addition, when the OsFAD2 gene was transferred into an Arabidopsis thaliana fad2-1 mutant, it effectively restored wild-type fatty acid composition and growth characteristics. Stress tolerance and light regulatory elements were identified in the predicted promoter of the OsFAD2 gene. Exogenously supplied hormone affected the level of FAD2 mRNA accumulation, accompanied by a change of content of di-unsaturated fatty acid species in rice leaves. Furthermore, OsFAD2 enhanced tolerance to low temperature when overexpressed in rice at the vegetative stage. More importantly, the 35S::OsFAD2 plants showed significantly enhanced cold tolerance at the reproductive stage, increasing grain yield by 46% over controls in the greenhouse under cold conditions. These results indicated that OsFAD2 is involved in fatty acid desaturation and maintenance of the membrane lipids balance in cells, and could improve the tolerance of yeast and rice to low temperature stress.

Oryza rufipogon L. (O. rufipogon) or a common wild rice, showed considerable aluminum (Al) tolerance. In this study, we examined the physiologic and genetic response of wild rice short term and long term to Al toxicity, respectively. In the short term study, morin staining, DAPI staining and aniline blue staining were used to detect Al distribution, cell division and callose production in the roots of O. rufipogon. The results indicated cell division could be enhanced by Al within low concentration range. In the long term study, we chose Oryza sativa L (O. sativa) (the close sib of O. rufipogon) as a reference. It showed that O. rufipogon grew better than O. sativa when treated with Al of 1.4 mmol/l concentration and also experienced a short period of root growth stimulation. This study gave some basic data to explain the mechanisms Oryza rufipogon L. developed to deal with Al and lay a good foundation to further study. SSH (suppression subtractive hybridization) proved that transcripts of the small subunit of Rubisco and a Photosystem I P700 apoprotein were enhanced under long term Al treatment in wild rice. Further investigation via the assessment of the content of chlorophyll a, b indicated that the content of chlorophyll a, b in the leaves of O. rufipogon generally rose after Al treatment for 15 days. This indicated that intake of Al can affect photosynthesis of plant.

Unsaturated fatty acids are synthesized by fatty acid desaturase in plant, which play an important role in plant development and defense to abiotic stresses. The key enzymes for the conversion of oleic into linoleic acid were isolated from rice (Oryza sativa L.) and were designated OsFAD2 and OsFAD6, respectively. The open reading frame (ORF) of OsFAD2 was 1 167 bp in length, which encoded a 388 amino acids sequence with the isoelectric point of 8.17 and molecular mass of 52.24 kDa, the OsFAD2 protein contained a C-terminal ER retrieval motif. The ORF of OsFAD6 was 1 365 bp in length and the predicted OsFAD6 protein has 454 amino acids with an estimated molecular mass of 44.35 kDa and an isoelectric point of 9.24, the predicted OsFAD6 protein possessed a putative N-terminal plastidial signal peptide. Both of them had three his-boxes, which were peculiar to membrane integrated fatty acid desaturase by Clustal X analysis. RT-PCR analysis showed that both genes were expressed in all tissues rice seedlings, with the maximum transcript accumulation in leaves. Among FAD family members of Oryza sativa L., the mRNA abundance of OsFAD2 and OsFAD6 in leaves did not change under cold stress; however, the mRNA abundance of OsFAD7 and OsFAD8 increased in the same condition. It was also found that the expression of FAD family members had diurnal rhythm phenomena. Based on the results of this study, it suggested that diurnal rhythm expression of OsFAD6 and OsFAD7 was related to the change of NADPH abundance.

The methylation of histone H3 lysine 36 (H3K36) plays critical roles in brassinosteroid (BR)-related processes and is involved in controlling flowering time in rice (Oryza sativa). Although enzymes that catalyze this methylation reaction have been described, little is known about the recognition mechanisms to decipher H3K36 methylation information in rice. In this study, biochemical characterizations showed that MORF-RELATED GENE702 (MRG702) binds to trimethylated H3K4 and H3K36 (H3K4me3 and H3K36me3) in vitro. Similar to the loss-of-function mutants of the rice H3K36 methyltransferase gene SET DOMAIN GROUP725 (SDG725), the MRG702 knockdown mutants displayed typical BR-deficient mutant and late-flowering phenotypes. Gene transcription analyses showed that MRG702 knockdown resulted in the down-regulation of BR-related genes, including DWARF11, BRASSINOSTEROD INSENSITIVE1, and BRASSINOSTEROID UPREGULATED1, and several flowering genes, including Early heading date1 (Ehd1), Ehd2, Ehd3, OsMADS50, Heading date 3a, and RICE FLOWERING LOCUS T1. A binding analysis showed that MRG702 directly binds to the chromatin at target gene loci. This binding is dependent on the level of trimethylated H3K36, which is mediated by SDG725. Together, our results demonstrate that MRG702 acts as a reader protein of H3K4me3 and H3K36me3 and deciphers the H3K36 methylation information set by SDG725. Therefore, the role of MRG702 in the BR pathway and in controlling flowering time in rice is to function as a reader protein to decipher methylation information.