ABSTRACT
To investigate the causes of the "sugar receding" in 'Feizixiao' litchi (Litchi chinensis Sonn.) pulp, the main sugar contents and sucrose metabolism enzyme activities were measured in pulp obtained in 2020 and 2021. Pulp RNA obtained in 2020 was extracted at 35, 63, and 69 days after anthesis (DAA) for transcriptome sequencing analysis. The differential expression of genes was verified by real-time PCR for both years. The results showed that after 63 DAA, the contents of soluble sugars and sucrose decreased, and the contents of fructose and glucose increased in both years. The dynamic changes in sucrose metabolism enzyme activities were similar in both years. After 63 DAA, except for acid invertase (AI) in 2021, the activities of other enzymes decreased significantly, and the net activity of sucrose metabolism enzymes showed a strong sucrose cleavage activity. There were 18061, 19575, and 985 differentially expressed genes in 35 d vs. 63 d, 35 d vs. 69 d, and 63 d vs. 69 d, respectively. Ninety-one sugar metabolism genes were screened out, including sucrose synthase (SS), sucrose phosphate synthase (SPS), AI, neutral invertase (NI), hexokinase (HK), glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), phosphofructokinase (PFK), and pyruvate kinase (PK) genes. In 63 d vs. 69 d, seventy-five percent of sucrose metabolism genes were downregulated, seventy-seven percent of genes in glycolysis (EMP) were upregulated and the PFK genes were significantly upregulated. There was a significant linear correlation between the expression of 15 genes detected by real-time PCR and the transcriptome sequencing results (r2020 = 0.9139, r2021 = 0.8912). These results suggest that the upregulated expression of PFK genes at maturity may enhance PFK activity and promote the degradation of soluble sugar in pulp through the EMP pathway, resulting in decreased soluble sugar and sucrose contents and "sugar receding" in pulp. Moreover, the downregulated expression of sucrose metabolism genes in pulp decreased the activities of these enzymes, but the net activity of these enzymes resulted in cleaved sucrose and replenished levels of reducing sugars, resulting in a stable reducing sugar content.
ABSTRACT
Due to the significant impact of processing on the performance of polymer products, it is crucial to develop in-line monitoring methods on processing. Based on the feedback data from in-line monitoring the processing parameters can be adjusted, which will contribute to the stability of production, thereby ensuring product quality, reducing energy waste and improving production efficiency. Near infrared spectroscopy (NIR), a low-cost, real-time and accurately quantitative analysis technology, has been widely used in many areas but still under study in polymer processing. The applications of in-line NIR monitoring technology in measuring the content of component, melt index, melt density and dispersion of filler of polymer during processing were reviewed. The existing problems about in-line NIR monitoring technology were pointed out, as well as the suggestions for the corresponding problems. The future trends of in-line NIR monitoring technology were discussed. With the development of fiber optic spectrometer, computer science and chemometrics, it is foreseen that the in-line NIR monitoring technology will make considerable progress in the stability of raw data, methods of pretreatment and modeling, the robustness and accuracy of model. Therefore, in-line NIR monitoring technology will be applied to more areas generating the great economic and environmental value.
ABSTRACT
OBJECTIVE: To establish a microemulsion liquid chromatography system with direct sample loading for determining the serum level of emodin in rats. METHODS: The separation was performed on C18 column (Hypersil BDS, 5 µm,150 mm×4.6 mm) with the microemulsion mobile phase consisting of 3.3% (w/V) SDS, 6.6% (V/V) n-butyl alcohol, and 1.0% (V/V) octane and water. The flow rate was 1.0 ml/min and the detection wavelength was 254 nm. RESULTS: The linear range of emodin detection was 0.333-5.32 µg/ml. The average recovery was 99.65% with a RSD of 3.60%. The limit of quantification was 0.1386 µg/mL. CONCLUSION: Microemulsion liquid chromatography system with direct sample loading allows simple, accurate and rapid determination of emodin in rat serum.
