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173 results on '"Shi, Xiao‐Mei"'

6. Simultaneous determination of 20 kinds of mycotoxins in maize straw feed by QuEChERS-ultra performance liquid chromatography-triple quadrupole mass spectrometry.

Author

LIU Ting-ting, ZHANG Wei-wei, SHI Xiao-mei, ZHAI Chen, HU Li-ming, QIAN Chen-jing, and ZHANG Xiao-lin

Subjects
MYCOTOXINS, MASS spectrometry, QUADRUPOLES, MEMBRANE filters, STANDARD deviations, CORNSTALKS
Abstract

The experiment was to establish an analytical method for the simultaneous determination of 20 kinds of mycotoxins in maize straw feed by QuEChERS-UPLC-MS/MS. The samples were extracted with acetonitrile-acetic acid (95 : 5), and the supernatant was purified by anhydrous MgSO4, PSA and C18. Then an appropriate amount of supernatant was blown to dry with nitrogen. The samples were reconstituted with methanol-water-acetic acid (30 : 70 : 0.1), passed through a PTFE filter membrane, and separated on a C18 chromatographic column. Using the multiple reaction monitoring (MRM) scan mode to monitor the target compounds and the results were quantified by the external standard method. The results showed that the linear ranges of the 20 mycotoxins were good, and the correlation coefficients (R²) were greater than 0.99. The limits of detection were 0.15~3.10 µg/kg, with limits of quantification were 0.49~10.33 µg/kg. The recoveries at the three levels were within the range of 70.4%~118.3%, with relative standard deviations of 1%~10% (n=6). The study indicates that the method was easy to operate, reproducible and highly accurated and sensitive, which can be used for routine screening of mycotoxins in corn stalk feed. [ABSTRACT FROM AUTHOR]

Published
2023
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16. Screening and Physiological Mechanism Analysis of Heat-resistant Sweet Potato Varieties.

Author

SHI Xiao-mei

Abstract

In order to screen and obtain the heat-resistant varieties of sweet potato, four high-quality sweet potato varieties were used as the research objects. The heat resistance evaluation value, SPAD value, hydrogen peroxide (H202) content, malondialdehyde (MDA) content, catalase (CAT) activity and ascorbate peroxidase (APX) activity of leaves were used as the heat resistance indexes. Then, the effects of high temperature stress on the leaf physiology and antioxidant enzyme activity of sweet potatoes were investigated by comparing the differences of various leaf indexes of four varieties of sweet potatoes under the high temperature stress of 35 °C and 40'C. The results showed that there was no significant change in leaf morphology of the four sweet potato varieties under the high temperature stress of 35'C. Under the high temperature stress of 40°C, the leaves of Longshu 116 and Pushu 23 showed obvious water loss curl, and the SPAD value was significantly lower than that of Jinshan 57 and Guangshu 87. The content of H2O2 in leaves was as high as 2.53 nmol ⋅ g-1 and 4. 21 nmol ⋅ g-1, which resulted in the increase of CAT and APX activity, and the content of MDA was significantly higher than that of Jinshan 57 and Guangshu 87, which were up to 10.06 nmol ⋅ g-1 and 14.94 nmol ⋅ g-1. According to the comprehensive evaluation, Guangshu 87 was the best sweet potato variety with excellent heat resistance in the tested varieties, followed by Jinshan 57. The results could provide the heat-resistant variety resources for the planting industry of sweet potato and provide theoretical basis for the breeding of heat-resistant varieties of sweet potato. [ABSTRACT FROM AUTHOR]

Published
2023
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29. Regulation of meiotic chromatin loop size by chromosomal position

Author

Heng, Henry H.Q., Chamberlain, John W., Shi, Xiao-Mei, Spyropoulos, Barbara, Tsui, Lap-Chee, and Moens, Peter B.

Subjects
Chromatin -- Research, Meiosis -- Research, Chromosomes -- Research, Science and technology
Abstract

At meiotic prophase, chromatin loops around a proteinaceous core, with the sizes of these loops varying between species. Comparison of the morphology of sequence-related inserts at different sites in transgenic mice demonstrates that loop size also varies with chromosomal geography. Similarly, chromatin loop lengths differ dramatically for interstitially and terminally located hamster telomeric sequences. Sequences, telomeric or otherwise, located at chromosome termini, closely associate with the meiotic proteinaceous core, forming shorter loops than identical interstitial sequences. Thus, we present evidence that different chromatin packaging mechanisms exist for interstitial versus terminal chromosomal regions, which act separately from those operating at the level of the DNA sequence. Chromosomal position plays the dominant role in chromatin packaging.

Published
1996

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