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OBJECTIVE To establish HPLC fingerprint of Portulaca oleracea， establish quantitative analysis of multi- components by single-marker （QAMS） method for the content determination of caffeic acid， ferulic acid， genistin and quercetin， and provide reference for quality control of the medicine. METHODS The determination was performed on Eclipse XDB-C18 column with mobile phase consisted of methanol-0.2% phosphoric acid solution （gradient elution） at the flow rate of 1.0 mL/min. The column temperature was 25 °C， and detection wavelength was set at 360 nm. The sample size was 10 μL. HPLC fingerprint of P. oleracea was established according to the above chromatographic conditions. Cluster analysis （CA） and principal component analysis （PCA） were performed for 15 batches of specimens. Using caffeic acid as internal standard， relative correction factors of other three components were calculated by QAMS， and then the component content was calculated on the basis of relative correction factors， which was compared with the external standard method. RESULTS HPLC fingerprints of 15 batches of P. oleracea were calibrated with a total of 17 common peaks， and 4 components （caffeic acid， ferulic acid， genistin， quercetin） were identified； the similarities of 15 batches of samples were greater than 0.890. The results of CA showed that S1-S10 were clustered into one category， and S11-S15 were clustered into one category. The results of PCA revealed that the accumulative contribution rate of the two main components was 92.502%， and the classification results were basically consistent with CA. The linear range of caffeic acid， ferulic acid， genistin and quercetin were 0.003 1-0.157 1， 0.003 6-0.181 7， 0.008 5-0.425 6，0.000 4-0.021 8 mg/mL （R2≥0.999 7）； the results of precision， repeatability， stability （24 h） and recovery tests all complied with the requirements of Chinese Pharmacopoeia. The relative correction factors of ferulic acid， genistin and quercetin calculated by QAMS were 1.534， 5.302 and 0.174； there was no significant difference in the contents of components measured between this method and the external standard method. CONCLUSIONS The established HPLC fingerprint combined with QAMS can be used for the quality control of multiple index components in P. oleracea. The origin has a certain influence on the quality of P. oleracea， and the quality of P. oleracea produced in Sichuan is better than that produced in Anhui and Hebei.
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Global warming has induced higher frequencies of excessively high-temperature weather episodes, which pose damage risk to rice growth and production. Past studies seldom specified how high temperature-induced carbohydrate metabolism disturbances from both source and sink affect rice fertilization and production. Here we discuss the mechanism of heat-triggered damage to rice quality and production through disturbance of carbohydrate generation and consumption under high temperatures. Furthermore, we provide strong evidence from past studies that rice varieties that maintain high photosynthesis and carbohydrate usage efficiencies under high temperatures will suffer less heat-induced damage during reproductive developmental stages. We also discuss the complexity of expressional regulation of rice genes in response to high temperatures, while highlighting the important roles of heat-inducible post-transcriptional regulations of gene expression. Lastly, we predict future directions in heat-tolerant rice breeding and also propose challenges that need to be conquered in the future.
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Metabolismo dos Carboidratos/genética , Regulação da Expressão Gênica de Plantas , Temperatura Alta , Oryza/genética , Oryza/metabolismo , Metabolismo Energético/genética , Fatores de Transcrição/metabolismoRESUMO
The RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 is the core machinery responsible for the viral genome replication and transcription and also a major antiviral target. Here we report the cryo-electron microscopy structure of a post-translocated SARS-CoV-2 RdRp core complex, comprising one nsp12, one separate nsp8(I) monomer, one nsp7-nsp8(II) subcomplex and a replicating RNA substrate. Compared with the recently reported SARS-CoV-2 RdRp complexes, the nsp8(I)/nsp7 interface in this RdRp complex shifts away from the nsp12 polymerase. Further functional characterizations suggest that specific interactions between the nsp8(I) and nsp7, together with the rearrangement of nsp8(I)/nsp7 interface, ensure the efficient and processive RNA synthesis by the RdRp complex. Our findings provide a mechanistic insight into how nsp7 and nsp8 cofactors regulate the polymerase activity of nsp12 and suggest a potential new intervention interface, in addition to the canonical polymerase active center, in RdRp for antiviral design. Author summarySince it was first discovered and reported in late 2019, the coronavirus disease 2019 (COVID-19) pandemic caused by highly contagious SARS-CoV-2 virus is wreaking havoc around the world. Currently, no highly effective and specific antiviral drug is available for clinical treatment. Therefore, the threat of COVID-19 transmission necessitates the discovery of more effective antiviral strategies. Viral RNA-dependent RNA polymerase (RdRp) is an important antiviral drug target. Here, our cryo-EM structure of a SARS-CoV-2 RdRp/RNA replicating complex reveals a previously uncharacterized overall shift of the cofactor nsp8(I)/nsp7 interface, leading to its rearrangement. Through in vitro functional test, we found that the specific interactions on the interface are important to the efficient RNA polymerase activity of SARS-CoV-2 RdRp. These observations let us to suggest this interface as a potential new drug intervention site, outside of the canonical polymerase active center, in RdRp for antiviral design. Our findings would provide new insights into regulatory mechanism of this novel SARS-CoV-2 RdRp, contribute to the design of antiviral drugs against SARS-CoV-2, and benefit the global public health.
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<p><b>OBJECTIVE</b>To study the expression of autophagy-related proteins (Beclin-1, LC3 and p62) in brain tissue with malformations of cortical development and related molecular pathogenesis.</p><p><b>METHODS</b>The brain tissue of 18 cases with epileptogenic foci resection, including 6 cases of tuberous sclerosis complex (TSC), 6 cases of focal cortical dysplasia type IIb (FCD IIb) and 6 cases of focal cortical dysplasia type I (FCD I), were retrieved. Immunohistochemical study for Beclin-1, LC3 and p62 proteins was performed. The degree of positivity for Beclin-1 and LC3 proteins was compared. Western blot was used to quantitatively analyze the LC3 protein in focal lesion of each disease groups.</p><p><b>RESULTS</b>Immunohistochemical study showed that the three proteins were mainly expressed in the dysmorphic neurons and balloon cells/giant cells of TSC and FCD IIb. The positivity was more intense in the dysmorphic neurons than the other cell types. Immunostaining for Beclin-1 showed granular or diffuse cytoplasmic positivity, in addition to the strong expression in axons. On the other hand, LC3 showed diffuse or perinuclear cytoplasmic expression. The staining for p62 was mainly cytoplasmic or perinuclear and sometimes nuclear. In FCD type I, only individual cells showed positive expression for the three proteins. The number of Beclin-1 and LC3-positive cells was larger in TSC group, followed by FCD IIb group and FCD I group.And there were significant differences between TSC group and FCD I group, as well as FCD IIb group and FCD I group (P<0.05). Quantitative expression of LC3 protein by Western blot showed smaller amount in TSC group, followed by FCD IIb group and FCD I group.</p><p><b>CONCLUSIONS</b>The dysmorphic neurons and balloon cells/giant cells of TSC and FCD IIb show abnormality in autophagy, resulting in intracytoplasmic protein accumulation. There are differences in molecular pathogenesis in these cell types.</p>
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A strain of canine parvovirus (CPV) was isolated from feces of an ill puppy in an animal hospital in Wuhan, China. It was designated as CPV/WH02/06. This isolate was identified as serotype CPV-2a by the hemagglutination test, CPV Ag detection strip, electron microscopy, and PCR. The vp2 gene was cloned and sequenced and assigned GenBank accession number EU377537. A 1242 bp segment of the 5' region of the vp2 gene was cloned and inserted into the binary vector pBI121 and used for Agrobacterium-mediated tobacco transformation. Transgenic tobacco plants were selected on MS medium supplemented with 100 μg/mL kanamycin and 100 μg/mL timentin. Integration of the vp2 gene into the tobacco genome was confirmed by PCR using T1 progeny plants, and the expression of the VP2 protein was confirmed by Western blotting.
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Studies have shown that transgenic plants expressing antiapoptotic genes from baculovirus and animals increase resistance to biotic and abiotic stress. However, the mechanism under these resistances is conjectural, or in some cases even controversy. In the present study, the p35 gene from baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) was expressed in tobacco, and for the first time P35 protein was detected in transgenic plants by Western blotting. Inoculation of T1 transgenic tobacco leaves with tobacco mosaic virus (TMV) showed enhanced resistance, and DNA laddering was observed after TMV infection in control but not in transgenic plants. DAB staining showed that TMV infection did not affect peroxide induction of transgenic plants, Western blotting analysis of PR1 protein also showed no difference of control and transgenic plants. Inoculation of fungus (Sclerotinia sclerotiorum) using a detached leaf assay showed enhanced resistance of transgenic leave tissue. RT-PCR analysis demonstrated that p35 gene expression induced earlier expression of PR1 gene after S. sclerotiorum infection. Taken together, our results suggest that the mechanism under enhanced disease resistance by P35 protein is possibly related to the activation of PR-related proteins in addition to the inhibition of programmed cell death, depending on the pathogens challenged.
