Structural and physicochemical properties of rice starch from a variety with high resistant starch and low amylose content.

Research on the physicochemical properties of rice-derived endo-sperm high resistant starch (RS) with low amylose content (AC) is limited. In this study, we evaluated the physicochemical characteristics of such a starch variety and revealed that the starch granules exhibit a smoother, more refined surface with distinct edges, increased compactness, higher order of surface, and fewer cavities compared to those of a low RS rice variety. The starch crystal was classified as an A-type, which may be connected to the high amylose-lipid complex content. The branched internal long chains (B2 + B3) were abundant, allowing for easy entanglement with other molecular chains and a compact structure. Differential scanning calorimetry revealed the need for high temperature and energy to disrupt the double helix structure within the crystallization region of starch. Furthermore, starch viscosity analysis revealed a high cold paste viscosity, consistency, and setback value, with recrystallization yielding a stable structure, increased viscosity, and enhanced hydrolysis resistance to enzymes.

Phytoalexin sakuranetin attenuates endocytosis and enhances resistance to rice blast.

Phytoalexin sakuranetin functions in resistance against rice blast. However, the mechanisms underlying the effects of sakuranetin remains elusive. Here, we report that rice lines expressing resistance (R) genes were found to contain high levels of sakuranetin, which correlates with attenuated endocytic trafficking of plasma membrane (PM) proteins. Exogenous and endogenous sakuranetin attenuates the endocytosis of various PM proteins and the fungal effector PWL2. Moreover, accumulation of the avirulence protein AvrCO39, resulting from uptake into rice cells by Magnaporthe oryzae, was reduced following treatment with sakuranetin. Pharmacological manipulation of clathrin-mediated endocytic (CME) suggests that this pathway is targeted by sakuranetin. Indeed, attenuation of CME by sakuranetin is sufficient to convey resistance against rice blast. Our data reveals a mechanism of rice against M. oryzae by increasing sakuranetin levels and repressing the CME of pathogen effectors, which is distinct from the action of many R genes that mainly function by modulating transcription.

SARS-Cov-2 spike induces intestinal barrier dysfunction through the interaction between CEACAM5 and Galectin-9.

Background: Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5), as a typical tumor marker, has been found to exert immunomodulatory effects in many diseases. We previously reported the clinical and molecular evidences supporting that SARS-Cov-2 infected the gastrointestinal (GI) tract and found a reduction of CEACAM5 in COVID-19 patients' feces which associated with gut dysbiosis. Yet the role of CEACAM5 in GI infection is ill-defined. Methods: Mice models were established through intraperitoneally injecting with recombinant viral spike-Fc to mimic the intestinal inflammation. We collected duodenum, jejunum, ileum and colon samples after 6h, 2 days, 4 days and 7 days of spike-Fc or control-Fc injection to perform proteomic analysis. Blood was collected from healthy donors and peripheral blood mononuclear cells (PBMC) were separated by density gradient centrifugation, then CD4+ T cells were isolated with magnetic beads and co-cultured with Caco-2 cells. Results: In addition to intestinal CEACAM5, the expression of tight junction and the percent of CD4+ T lymphocytes were significantly decreased in spike-Fc group compared to control (p < 0.05), accompanied with increased level of inflammatory factors. The KEGG analysis revealed differentially expressed proteins were mainly enriched in the coronavirus disease (COVID-19), tight junction, focal adhesion, adherens junction and PI3K-Akt signaling pathway. Protein-protein interaction (PPI) network analysis identified the interaction between CEACAM5 and Galectin-9 that was also verified by molecular docking and co-IP assay. We further confirmed a reduction of CEACAM5 in SARS-CoV-2 spike stimulated enterocytes could promote the expression of Galectin-9 protein in CD4+T cells. Then it gave rise to the increasing release of inflammatory factors and increased apoptosis of CD4+T cells by inhibition of PI3K/AKT/mTOR pathway. Ultimately intestinal barrier dysfunction happened. Conclusion: Our results indicated that CEACAM5 overexpression and Galectin-9 knockdown played a protective role in intestinal barrier injury upon spike-Fc stimulation. Collectively, our findings identified firstly that SARS-CoV-2 spike induced intestinal barrier dysfunction through the interaction between CEACAM5 and Galectin-9. The result provides potential therapeutic targets in intestinal barrier dysfunction for treating severe COVID patients.

Analysis of the Differences in Volatile Organic Compounds in Different Rice Varieties Based on GC-IMS Technology Combined with Multivariate Statistical Modelling.

In order to investigate the flavour characteristics of aromatic, glutinous, and nonaromatic rice, gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyse the differences in volatile organic compounds (VOCs) amongst different rice varieties. The results showed that 103 signal peaks were detected in these rice varieties, and 91 volatile flavour substances were identified. Amongst them, 28 aldehydes (28.89~31.17%), 24 alcohols (34.85~40.52%), 14 ketones (12.26~14.74%), 12 esters (2.30~4.15%), 5 acids (7.80~10.85%), 3 furans (0.30~0.68%), 3 terpenes (0.34~0.64%), and 2 species of ethers (0.80~1.78%) were detected. SIMCA14.1 was used to perform principal component analysis (PCA) and orthogonal partial least squares discriminant analysis, and some potential character markers (VIP > 1) were further screened out of the 91 flavour substances identified based on the variable important projections, including ethanol, 1-hexanol, hexanal, heptanal, nonanal, (E)-2-heptenal, octanal, trans-2-octenal, pentanal, acetone, 6-methyl-5-hepten-2-one, ethyl acetate, propyl acetate, acetic acid, and dimethyl sulphide. Based on the established fingerprint information, combined with principal component analysis and orthogonal partial least squares discriminant analysis, different rice varieties were also effectively classified, and the results of this study provide data references for the improvement in aromatic rice varieties.

Transcriptome Analyses Show Changes in Gene Expression Triggered by a 31-bp InDel within OsSUT3 5'UTR in Rice Panicle.

Pollen development and its fertility are obligatory conditions for the reproductive success of flowing plants. Sucrose transporter 3 (OsSUT3) is known to be preferentially expressed and may play critical role in developing pollen. A 31-bp InDel was identified as a unique variation and was shown to be responsible for the expression of downstream gene in our previous study. In this study, to analyze the changes of gene expression triggered by 31-bp InDel during pollen development, two vectors (p385-In/Del::OsSUT3-GUS) were constructed and then stably introduced into rice. Histochemical and quantitative real-time PCR (qRT-PCR) analysis of transgenic plants showed that 31-bp deletion drastically reduced the expressions of downstream genes, including both OsSUT3 and GUS in rice panicle at booting stage, especially that of OsSUT3. The transcriptome profile of two types of panicles at booting stage revealed a total of 1028 differentially expressed genes (DEGs) between 31-bp In and 31-bp Del transgenic plants. Further analyses showed that 397 of these genes were significantly enriched for the 'metabolic process' and 'binding'. Among them, nineteen genes had a strong relationship with starch and sucrose metabolism and were identified as candidate genes potentially associated with the starch accumulation in rice pollen, which that was also verified via qRT-PCR. In summary, 31-bp InDel plays a crucial role not only in the regulation of downstream genes but in the expression of sucrose-starch metabolizing genes in multiple biological pathways, and provides a different regulation mechanism for sucrose metabolism in pollen.

Identification of the Core Pollen-Specific Regulation in the Rice OsSUT3 Promoter.

The regulatory mechanisms of pollen development have potential value for applications in agriculture, such as better understanding plant reproductive regularity. Pollen-specific promoters are of vital importance for the ectopic expression of functional genes associated with pollen development in plants. However, there is a limited number of successful applications using pollen-specific promoters in genetic engineering for crop breeding and hybrid generation. Our previous work led to the identification and isolation of the OsSUT3 promoter from rice. In this study, to analyze the effects of different putative regulatory motifs in the OsSUT3 promoter, a series of promoter deletions were fused to a GUS reporter gene and then stably introduced into rice and Arabidopsis. Histochemical GUS analysis of transgenic plants revealed that p385 (from -385 to -1) specifically mediated maximal GUS expression in pollen tissues. The S region (from -385 to -203) was the key region for controlling the pollen-specific expression of a downstream gene. The E1 (-967 to -606), E2 (-202 to -120), and E3 (-119 to -1) regions enhanced ectopic promoter activity to different degrees. Moreover, the p385 promoter could alter the expression pattern of the 35S promoter and improve its activity when they were fused together. In summary, the p385 promoter, a short and high-activity promoter, can function to drive pollen-specific expression of transgenes in monocotyledon and dicotyledon transformation experiments.

Several types of soft tissue sarcomas originate from the malignant transformation of adipose tissue-derived stem cells.

The cellular origin of soft tissue sarcomas (STSs) is not fully understood. The cancer stem cell hypothesis presumes that tumors originate from the malignant transformation of stem cells. As a type of multipotent stem cell, adipose tissue-derived stromal/stem cells (ADSCs), which possess an unexpected degree of plasticity and often reside in other tissues, may represent a potential source of soft tissue sarcoma. To ascertain whether ADSCs are responsible for the formation of STSs, ADSCs from mice were cultured and treated with 3-methycholanthrene to derive transformed cells. These transformed ADSCs were then injected subcutaneously into immunodeficient mice to test their tumorigenic potential. We found that they generated several types of STSs, including synovial sarcoma, malignant fibrous histiocytoma and fibrosarcoma. This is the first study to report that ADSCs may be the potential initiating cells for synovial sarcoma. Our findings indicate that STSs might originate from malignantly transformed ADSCs.

Segregation distortion detected in six rice F2 populations generated from reciprocal hybrids at three altitudes.

This paper presents investigations of segregation distortion of six rice F2 populations generated from reciprocal F1 hybrids grown at three locations varied at altitudes from 400 to 2200 m. The F1s were derived from reciprocal crosses between cv. XMG, which is a japonica landrace traditionally grown at 2650 m altitude, and cv. N34, which is a japonica restorer possessing a fertility restoring (Rf) gene and cytoplasm of male sterility (CMS) donated by an indica cultivar. Among nine morphological traits of the F2 populations, only one was in normal distribution, eight were distorted in all or at least one population. Out of 16 polymorphic PCR markers, 10 markers distributed on 7 chromosomes were significantly distorted. Among these markers, RMAN7 and RM257 were distorted in both of the reciprocal populations, which suggested that nuclear genes had strong effects on segregation distortion. The other makers were distorted only in the populations with cytoplasm donated by XMG or N34. The results indicated that segregation of DNA markers was affected by cytoplasm background. Segregation distribution was also affected by altitude, since segregation distortions of most of the markers were detected not in all the three populations generated from F1 grown at the three altitudes, but only in one population from F1 grown at one altitude. Marker M45461, which is located within Rf-1 locus, was severely distorted towards N34 in all the populations with cytoplasm donated by N34, but not in the populations with cytoplasm provided by XMG. The results indicated that interaction between CMS and Rf gene had strong effects on distortion. Results of this study indicated that japonica cytoplasm did not cause distortion favouring a special parent, but indica cytoplasm made distortion favouring a maternal parent. The results suggested that indica cytoplasm was not well compatible with japonica nuclear background, while japonica cytoplasm did not have such trouble with indica nuclei. This study also found that the six F2 populations were divergent into two groups due to difference of cytoplasm background.

A novel mutated cell line with characteristics of dedifferentiated chondrosarcoma.

Dedifferentiated chondrosarcoma (CS) is a rare, highly malignant variant of CS in which a high-grade sarcoma coexists with a low-grade chondroid tumor. In this study, a novel dedifferentiated CS cell line, MS0812, was spontaneously established from mutated human embryonic muscle cells. Several features of the cell line were investigated, including growth characteristics, cytogenetics, electron microscopic features, expression of various antigenic markers and tumor formation. MS0812 has been cultured continuously for more than 3 years. The growth characteristics of MS0812 are similar to the immortalized cell lines as reported. The cell line exhibited complex karyotypes and hyperploidy, the chromosome number ranged from 50 to 158. MS0812 was positive for vimentin, desmin and muscle actin, indicating their muscle origin. With specific inductive condition, MS0812 differentiates into neural cells and adipocytes. Deletion of the p16 gene, which seemed to play a major role in the malignant phenotype of this cell line, was confirmed by PCR and immunocytochemistry. MS0812 formed tumors in nude mice, and the tumor revealed a fibrosarcoma with chondroid components, which were consistent with dedifferentiated CS as reported. Chondroid components showed metachromasia by Alcian blue and toluidine blue and were S100 and collagen-II positive. To our knowledge, this is the first report of the establishment of a human dedifferentiated chondrosarcoma from mutated human embryonic muscle cells, and it is a useful model for the study of the molecular pathogenesis of dedifferentiated CS.

[Long-term culture and differentiation of human glioma stem cells ].

OBJECTIVE: To explore the culture and subculture conditions for glioma stem cells(GSCs) and to investigate the differentiation potential of GSCs. METHODS: The cells from human glioma were mechanically dissociated. Cells were cultured in N2 or B27 medium with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF), and they were identified by immunocytochemistry. RESULTS: Glioma stem cells from human glioma have been successfully cultured. They formed typical neurospheres in suspension, and they could be cultured and passaged steadily in vitro. The majorities of the cells expressed vimentin and nestin, which were the markers for neural stem cells. They could differentiate into neurons and astrocytes, and express glial fibrillary acidic protein and beta III-tubulin respectively. CONCLUSION: Human glioma stem cells could be cultured from gliomas in vitro, and they could differentiate into neurons and astrocytes, thus providing a basis for further studies.