色素基因工程与棉花纤维色泽改良

介绍了植物色素基因研究的最新进展及如何利用基因工程转化棉花的方法。     

Analysis of crab meat volatiles as possible spoilage indicators for blue crab (Callinectes sapidus) meat by gas chromatography–mass spectrometry

Traditionally crab meat spoilage has been evaluated using sensory panels. A method was developed using solid-phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) to examine the aroma profile of blue crab (Callinectes sapidus) for chemical indicators of spoilage. The chemicals found to correlate best with spoilage were trimethylamine (TMA), ammonia, and indole over a period of 7 days. In addition, chemicals previously not identified in the aroma profile of blue crab were tentatively detected. Scan mode of the mass spectrometer was used to qualitatively determine compounds extracted from the volatile profile of spoiling blue crab by the SPME fiber. Selected ion monitoring (SIM) mode of the mass spectrometer improved resolution, identified compounds at low concentrations, and allowed spoilage related compounds to be detected in one chromatographic run without sample heating. TMA increased linearly. A significant difference in TMA concentrations were found for day 0 and day 4 samples. Indole concentrations corresponded well with sensory and microbial evaluations, in early, mid, and highly spoiled crab meat samples.     

Colorimetric monitoring of the activity of recombinant Escherichia coli expressing styrene monooxygenase

Biocatalysis using recombinant Escherichia coli expressing styrene monooxygenase (SMO) activity is recognized as a promising process for the production of enantiopure aryl epoxides such as (S)-styrene oxide. Generally the activity of the whole cell biocatalyst is determined by measuring the conversion of styrene into (S)-styrene oxide by gas chromatography, which is however improper for the high-throughput analysis of many samples. Here we present that styrene monooxygenase catalyzed conversion of indole into indigo can be employed to monitor the activity of recombinant E. coli expressing styrene monooxygenase. We first confirmed that the colorimetric method was effective to monitor the whole cell activity of SMO by comparing the E. coli expressing styAB with that expressing only styB in a solid culture system. Next we used the monitoring method to investigate the effect of chaperone coexpression on the SMO whole cell activity in a liquid culture system.     

Kinetics of extracted bioactive components from mushrooms in artificial digestive juices

This article presents a study on fruiting bodies of Boletus badius, Boletus edulis, Cantharellus cibarius, Lactarius deliciosus, Leccinum scabrum, Suillus bovinus, Suillus luteus, Pleurotus ostreatus, Tricholoma equestre, Armillaria mellea, Agaricus bisporus, and Auricularia polytricha. The amounts of their health-promoting bioelements and physiologically significant indole and phenolic compounds were determined. The significance of edible mushrooms in the human diet and in disease prevention were also established. The high-performance liquid chromatography was used to assess the contents of indole compounds and phenolic acids. The atomic absorption spectroscopy was applied to determine bioelements. In all samples, the content of 5-hydroxy-L-tryptophan was studied. The highest extraction amount of serotonin was found for P. ostreatus species. Phenolic compounds were determined in the conditions described in the present study for the first time. Additionally, protocatechuic, p-hydroxybenzoic, syringic, and gallic acids were determined.     

Effective adsorptive denitrogenation from model fuels over yttrium ionexchanged Y zeolite

The adsorption removal of indole and quinoline in octane with and without toluene over zeolites NaY and Yttrium Ion-exchanged Y(YY) using batch adsorption experiments was studied at 25 ℃ and 0.1 MPa. YY was prepared by treating NaY with Y(NO_3)_3 solution twice via liquid ion-exchange method. NaY and YY were both characterized by XRD, SEM, N_2 adsorption, XRF, NH_3-TPD, and pyridine-FTIR techniques. Adsorption isotherms of indole, quinoline and toluene in octane were conducted at 25.0 ℃ to explain the influence of toluene on nitrogen removal over NaY and YY. The partial destruct of the crystalline structure of NaY was observed after the introduction of yttrium ion, which led to an evident decline in BET surface area and pore volume of YY. Strong Br?nsted acidity and medium Lewis acidity were introduced by yttrium ion-exchange. Though the specific surface area and pore volume of YY were much lower than those of NaY, YY exhibited equivalent adsorption capacities for indole and quinoline as NaY in model fuels without toluene. In the presence of 20 vol% toluene, however,YY exhibited much higher adsorption capacities for indole and quinoline than NaY, especially in the case of quinoline. The improved toluene-tolerant of YY was ascribed to the strong acid–base interaction between YY and quinoline and the decreased adsorption strength between YY and toluene.     

Environment-friendly synthesis of nitrogen-containing heterocyclic compounds

A novel environment-friendly vapour phase synthesis of different classes of nitrogen-containing heterocyclic compounds was developed using non-hazardous, commercially available and low cost feeds. 2-Methyl-8-ethylquinoline (MEQUI) was obtained from 2-ethylaniline (2-ETAN) and ethylene glycol (EG) or chloroethanol (CE), operating at high temperature in the presence of acid-treated K10 montmorillonite or ZnCl₂/K10 montmorillonite. At lower temperatures and using copper chromite catalysts, 7-ethylindole (7-ETI) or 5-ethylindole (5-ETI) were obtained from 2-ETAN or 4-ethylaniline (4-ETAN), respectively, and EG; excess of alkylaniline was required to avoid the formation of polyalkylated by-products. Mixing SiO₂ with the best copper chromite, made it possible to operate with higher LHSV values, thus improving the yield in alkylindoles. Finally, N-(2-ethylphenyl)pyrrole (EPP) and N-(2-ethylphenyl)pyrrolidine (EPD) were synthesised using a commercial copper chromite catalyst and feeding 2-ETAN and 2,3-dihydrofuran (DHF), EPP being favoured by high temperatures and absence of water in the feed. The possible reaction pathway for each synthesis is proposed, to evidence the key features of the best catalysts identified.     

Selective C−H Bond Functionalization of Unprotected Indoles by Donor-Acceptor Carbene Insertion

Copper catalysts containing alkoxydiaminophosphine (ADAP) ligand catalyze the selective C3−H functionalization of unprotected indoles upon carbene transfer from donor-acceptor diazo compounds, the N−H bond remaining unaltered during the transformation. Mechanistic studies, including DFT calculations, allows proposing the existence of two competitive pathways, none of them occurring through the formation of cyclopropane intermediates, at variance with previously reported systems.