Application Potential of Baijiu Non-Saccharomyces Yeast in Winemaking Through Sequential Fermentation With Saccharomyces cerevisiae.

To explore the potential application of non-Saccharomyces yeasts screened from Baijiu fermentation environment in winemaking, the effect of four Baijiu non-Saccharomyces yeasts (two Zygosaccharomyces bailii and two Pichia kudriavzevii) sequentially fermented with Saccharomyces cerevisiae on the physicochemical parameters and volatile compounds of wine was analyzed. The results indicated that there was no obvious antagonism between S. cerevisiae and Z. bailli or P. kudriavzevii in sequential fermentations, and all strains could be detected at the end of alcoholic fermentation. Compare with S. cerevisiae pure fermentation, Z. bailii/S. cerevisiae sequential fermentations significantly reduced higher alcohols, fatty acids, and ethyl esters and increased acetate esters; P. kudriavzevii/S. cerevisiae sequential fermentations reduced the contents of C6 alcohols, total higher alcohols, fatty acids, and ethyl esters and significantly increased the contents of acetate esters (especially ethyl acetate and 3-methylbutyl acetate). Sequential fermentation of Baijiu non-Saccharomyces yeast and S. cerevisiae improved the flavor and quality of wine due to the higher ester content and lower concentration of higher alcohols and fatty acids, non-Saccharomyces yeasts selected from Baijiu fermentation environment have potential applications in winemaking, which could provide a new strategy to improve wine flavor and quality.

Artificial nondirectional site-specific recombination systems.

Site-specific recombination systems (SRSs) are widely used in studies on synthetic biology and related disciplines. Nondirectional SRSs can randomly trigger excision, integration, reversal, and translocation, which are effective tools to achieve large-scale genome recombination. In this study, we designed 6 new nondirectional SRSs named Vika/voxsym1-4 and Dre/roxsym1-2. All 6 artificial nondirectional SRSs were able to generate random deletion and inversion in Saccharomyces cerevisiae. Moreover, all six SRSs were orthogonal to Cre/loxPsym. The pairwise orthogonal nondirected SRSs can simultaneously initiate large-scale and independent gene recombination in two different regions of the genome, which could not be accomplished using previous orthogonal systems. These SRSs were found to be robust while working in the cells at different growth stages, as well as in the different spatial structure of the chromosome. These artificial pairwise orthogonal nondirected SRSs offer newfound potential for site-specific recombination in synthetic biology.

The influence of dexmedetomidine on the emergence agitation of pediatric patients after the operations of sense organs under general anesthesia using sevoflurane.

BACKGROUND: We investigated the influence of dexmedetomidine on the emergence agitation of pediatric patients after ophthalmologic operation under general anesthesia using sevoflurane. METHODS: We selected 90 patients that were administered pediatric ophthalmologic operation for the study. The patients were randomly divided into 3 groups according to the administration way of drugs, i.e. the normal saline group (group S, N.=30), the midazolam group (group M, N.=30) and the dexmedetomidine group (group D, N.=30). For all patients, anesthesia induction was performed using sevoflurane before anesthesia, and the anesthesia was maintained in the operation with a combination of sevoflurane and remifentanil; laryngeal mask airway (LMA) was used for assisted ventilation. Ten minutes before the end of operation, 15 mL of 0.9% normal saline, 0.05 mg/kg of midazolam and 0.5 µg/kg of dexmedetomidine were administered to group S, group M and group D, respectively. After the operation, we observed the awakening time, time of the LMA removal as well as the recovery time in the Post Anesthesia Care Unit (PACU) of patients in all three groups. We evaluated the postoperative condition of sedation and agitation of the patients using Ramsay Sedation Scale, 5-point scale and Pediatric Anesthesia Emergence Deliriums Scale (PAED) and performed statistical analysis. RESULTS: In the comparisons of awakening time, time of the LMA removal as well as the recovery time, we found that group M was the longest sequentially followed by group D and group S with statistically significant differences (P<0.05). While the comparison of the scores of Ramsay Sedation Scale revealed that group D scored highest followed by group M and group S with statistically significant differences (P<0.05), both of the comparisons of the scores of 5-point scale and PAED Scale showed that group D scored the lowest, followed by group M and group S in sequence with statistically significant differences (P<0.05). CONCLUSIONS: Dexmedetomidine can significantly lower the incidence of emergence agitation of pediatric patients after the ophthalmologic operation under sevoflurane anesthesia.

Ethylenediamine pretreatment of corn stover facilitates high gravity fermentation with low enzyme loading.

This work investigated the effect of ethylenediamine pretreatment on reducing enzyme loading in high gravity fermentation. At optimal conditions of ethylenediamine pretreatment, 85.5% lignin was removed. Enzyme adsorption analysis using a fluorescent cellulose-binding protein showed 35.2% increase of productive adsorption of enzymes to ethylenediamine pretreated biomass, which was caused by high delignification and dramatically increased surface roughness and porosity. In SScF at 15% glucan loading, up to 82.2 g/L ethanol was achieved with a relatively low enzyme loading of 3.6 FPU/g dry matter. It suggested that the remarkably high digestibility of EDA pretreated corn stover could effectively reduce the enzyme loading in the high gravity fermentation of cellulosic ethanol.

Genome-wide landscape of position effects on heterogeneous gene expression in Saccharomyces cerevisiae.

BACKGROUND: Integration of heterogeneous genes is widely applied in synthetic biology and metabolic engineering. However, knowledge about the effect of integrative position on gene expression remains limited. RESULTS: We established a genome-wide landscape of position effect on gene expression in Saccharomyces cerevisiae. The expression cassette of red fluorescence protein (RFP) gene was constructed and inserted at 1044 loci, which were scattered uniformly in the yeast genome. Due to the different integrative loci on the genome, the maximum relative intensity of RFP is more than 13-fold over the minimum. Plots of the number of strains to RFP relative intensity showed normal distribution, indicating significant position effect on gene expression in yeast. Furthermore, changing the promoters or reporter genes, as well as carbon sources, revealed little consequences on reporter gene expression, indicating chromosomal location is the major determinant of reporter gene expression. CONCLUSIONS: We have examined the position effects to integration genes expression in large number loci around whole genome in S. cerevisiae. The results could guide the design of integration loci for exogenous genes and pathways to maximize their expression in metabolic engineering.

"Perfect" designer chromosome V and behavior of a ring derivative.

Perfect matching of an assembled physical sequence to a specified designed sequence is crucial to verify design principles in genome synthesis. We designed and de novo synthesized 536,024-base pair chromosome synV in the "Build-A-Genome China" course. We corrected an initial isolate of synV to perfectly match the designed sequence using integrative cotransformation and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated editing in 22 steps; synV strains exhibit high fitness under a variety of culture conditions, compared with that of wild-type V strains. A ring synV derivative was constructed, which is fully functional in Saccharomyces cerevisiae under all conditions tested and exhibits lower spore viability during meiosis. Ring synV chromosome can extends Sc2.0 design principles and provides a model with which to study genomic rearrangement, ring chromosome evolution, and human ring chromosome disorders.

Bug mapping and fitness testing of chemically synthesized chromosome X.

Debugging a genome sequence is imperative for successfully building a synthetic genome. As part of the effort to build a designer eukaryotic genome, yeast synthetic chromosome X (synX), designed as 707,459 base pairs, was synthesized chemically. SynX exhibited good fitness under a wide variety of conditions. A highly efficient mapping strategy called pooled PCRTag mapping (PoPM), which can be generalized to any watermarked synthetic chromosome, was developed to identify genetic alterations that affect cell fitness ("bugs"). A series of bugs were corrected that included a large region bearing complex amplifications, a growth defect mapping to a recoded sequence in FIP1, and a loxPsym site affecting promoter function of ATP2 PoPM is a powerful tool for synthetic yeast genome debugging and an efficient strategy for phenotype-genotype mapping.

[Genetic analysis in the clinical diagnosis of Ehlers-Danlos syndrome type IV].

OBJECTIVE: To ascertain the diagnosis of such a rare disease as Ehlers-Danlos syndrome type IV by the technique of DNA(deoxyribonucleic acid)analysis. METHODS: The primer sequences of Col3A1 gene were designed. Genomic DNA was isolated from the peripheral blood samples. The amplification of polymerase chain reaction (PCR) was performed and direct sequencing used to screen the mutations. A definite diagnosis was made in conjunctions with clinical features. RESULTS: Two nucleotide mutations for Col3A1 were found. One was in intron 15 while another in exon 30. The latter was an important mutation of a G to A transition (c.2209G > A) resulting in alanine to threonine substitution at position (p.Ala698Thr). The mutations were inherited from proband of pedigree. CONCLUSION: Genetic testing of Col3A1 mutation can facilitate an accurate diagnosis of Ehlers-Danlos syndrome.