RESUMEN
D-mannose is a natural hexose with great economic and application values in the food, medicine, and cosmetic fields. However, most biosynthesis methods of D-mannose rely on Escherichia coli as the host, which poses safety issues during the production process and imposes limitations on subsequent applications. This study compared the enzyme properties of mannose isomerases from multiple sources to select the most suitable source. B. subtilis 168/pMA5-EcMIaseA was constructed with "generally recognized as safe" (GRAS) Bacillus subtilis as the host and used as a whole-cell catalyst to synthesize D-mannose from d-fructose. Optimizing the conversion conditions such as culture temperature, pH, and substrate concentration increased the yield of D-mannose. The results showed that the conversion rates reached 27.75% and 27.22% and the yields of D-mannose were 138.74 g/L and 163.30 g/L after 6 h whole-cell transformation with d-fructose at the concentrations of 500 g/L and 600 g/L, respectively, in a 5 L fermentor. This study achieves the highest yield of D-mannose produced under the catalysis by recombinant B. subtilis that has ever been reported and provides a basis for the industrial production and application of D-mannose.
Asunto(s)
Bacillus subtilis , Fructosa , Manosa , Bacillus subtilis/metabolismo , Bacillus subtilis/genética , Manosa/metabolismo , Manosa/biosíntesis , Fructosa/metabolismo , Fructosa/biosíntesis , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMEN
Background: Early life stress (ELS) is a major risk factor for depression in adolescents. The nucleus accumbens (NAc) is a key center of the reward system, and spine remodeling in the NAc contributes to the development of depression. The Si-Ni-San formula (SNS) is a fundamental prescription for treating depression in traditional Chinese medicine. However, little is known about the effects of SNS on behavioral abnormalities and spine plasticity in the NAc induced by ELS. Purpose: This study aimed to investigate the therapeutic effect and the modulatory mechanism of SNS on abnormal behaviors and spine plasticity in the NAc caused by ELS. Methods: We utilized a model of ELS that involved maternal separation with early weaning to explore the protective effects of SNS on adolescent depression. Depressive-like behaviors were evaluated by the sucrose preference test, the tail suspension test, and the forced swimming test; anxiety-like behaviors were monitored by the open field test and the elevated plus maze. A laser scanning confocal microscope was used to analyze dendritic spine remodeling in the NAc. The activity of Rac1 was detected by pull-down and Western blot tests. Viral-mediated gene transfer of Rac1 was used to investigate its role in ELS-induced depression-like behaviors in adolescence. Results: ELS induced depression-like behaviors but not anxiety-like behaviors in adolescent mice, accompanied by an increase in stubby spine density, a decrease in mushroom spine density, and decreased Rac1 activity in the NAc. Overexpression of constitutively active Rac1 in the NAc reversed depression-related behaviors, leading to a decrease in stubby spine density and an increase in mushroom spine density. Moreover, SNS attenuated depression-like behavior in adolescent mice and counteracted the spine abnormalities in the NAc induced by ELS. Additionally, SNS increased NAc Rac1 activity, and the inhibition of Rac1 activity weakened the antidepressant effect of SNS. Conclusion: These results suggest that SNS may exert its antidepressant effects by modulating Rac1 activity and associated spine plasticity in the NAc.
RESUMEN
L-Homoserine is an important amino acid as a precursor in synthesizing many valuable products. However, the low productivity caused by slow L-homoserine production during active cell growth in fermentation hinders its potential applications. In this study, strategies of engineering the synthetic pathway combined with regulating cell division were employed in an L-homoserine-producing Escherichia coli strain for efficiently biomanufacturing L-homoserine. First, the flux-control genes in the L-homoserine degradation pathway were omitted to redistribute carbon flux. To drive more carbon flux into L-homoserine production, the phosphoenolpyruvate-pyruvate-oxaloacetate loop was redrawn. Subsequently, the cell division was engineered by using the self-regulated promoters to coordinate cell growth and L-homoserine production. The ultimate strain HOM23 produced 101.31 g/L L-homoserine with a productivity of 1.91 g/L/h, which presented the highest L-homoserine titer and productivity to date from plasmid-free strains. The strategies used in this study could be applied to constructing cell factories for producing other L-aspartate derivatives.
Asunto(s)
Escherichia coli , Homoserina , Escherichia coli/genética , Escherichia coli/metabolismo , Homoserina/genética , Homoserina/metabolismo , Ingeniería Metabólica , Fermentación , División CelularRESUMEN
Early-life stress (ELS) was found to increase the risk of adolescent depression, and clinical evidence indicated that eicosapentaenoic acid (EPA) was decreased in patients with adolescent depression, but the underlying mechanisms are unclear. Here, we utilized an ELS model of maternal separation with early weaning to explore the protective role of EPA in adolescent depression. We found that that ELS induced depression-like behavior rather than anxiety-like behavior in adolescent mice. RNA-sequencing results showed that ELS changed the transcription pattern in the liver, including 863 upregulated genes and 971 downregulated genes, especially those related to the biosynthesis of unsaturated fatty acids metabolism in the liver. Moreover, ELS decreased the expression of the rate-limiting enzymes, fatty acid desaturases 1/2 (FADS1/2), involved in the biosynthesis of EPA in the liver. Additionally, ELS reduced the levels of EPA in the liver, serum, and hippocampus, and EPA administration improved depression-like behavior-induced by ELS. Our results provide transcriptomic evidence that ELS increases the risk of adolescent depression by reducing the synthesis of unsaturated fatty acids in the liver, especially EPA, and suggest that supplementation with EPA should be investigated as a potential treatment for adolescent depression.
Asunto(s)
Depresión , Ácido Eicosapentaenoico , Estrés Psicológico , Animales , Ratones , Depresión/etiología , Depresión/genética , Modelos Animales de Enfermedad , Ácido Eicosapentaenoico/farmacología , Hígado , Privación Materna , TranscriptomaRESUMEN
2-O-α-D-glucopyranosyl-sn-glycerol (2-αGG) is a high value product with wide applications. Here, an efficient, safe and sustainable bioprocesses for 2-αGG production was designed. A novel sucrose phosphorylase (SPase) was firstly identified from Leuconostoc mesenteroides ATCC 8293. Subsequently, SPase mutations were processed with computer-aided engineering, of which the activity of SPaseK138C was 160% higher than that of the wild-type. Structural analysis revealed that K138C was a key functional residue moderating substrate binding pocket and thus influences catalytic activity. Furthermore, Corynebacterium glutamicum was employed to construct microbial cell factories along with ribosome binding site (RBS) fine-tuning and a two-stage substrate feeding control strategy. The maximum production of 2-αGG by these combined strategies reached 351.8 g·L-1 with 98% conversion rate from 1.4 M sucrose and 3.5 M glycerol in a 5-L bioreactor. This was one of the best performance reported in single-cell biosynthesis of 2-αGG, which paved effective ways for industrial-scale preparation of 2-αGG.
Asunto(s)
Leuconostoc mesenteroides , Leuconostoc mesenteroides/metabolismo , Glicerol , Sacarosa/metabolismo , Biotransformación , Leuconostoc/genética , Leuconostoc/metabolismoRESUMEN
Social isolation (SI) is a major risk factor for mood disorders in adolescents. The nucleus accumbens (NAc) is an important reward center implicated in psychiatric disorders. Resveratrol (RSV) is one of the most effective natural polyphenols with anti-anxiety and depression effects. However, little is known about the therapeutic effects and mechanisms of RSV on behavioral abnormality of adolescent social stress. Therefore, this study aimed to investigate the underlying mechanism of RSV on the amelioration of SI-induced behavioral abnormality. We found that SI induced anxiety-like behavior and social dysfunction in isolated female rats. Moreover, SI reduced mitochondrial number and ATP levels and increased thin spine density in the NAc. RNA sequencing results showed that SI changed the transcription pattern in the NAc, including 519 upregulated genes and 610 downregulated genes, especially those related to mitochondrial function. Importantly, RSV ameliorated behavioral and spine abnormalities induced by SI and increased NAc ATP levels and mitochondria number. Furthermore, RSV increased the activity of cytochrome C oxidase (COX) and upregulated mRNA levels of Cox5a, Cox6a1 and Cox7c. These results demonstrate that the modulation of spine plasticity and mitochondrial function in the NAc by RSV has a therapeutic effect on mood disorders induced by social isolation.
Asunto(s)
Núcleo Accumbens , Aislamiento Social , Animales , Ratas , Femenino , Núcleo Accumbens/metabolismo , Resveratrol/farmacología , Resveratrol/metabolismo , Aislamiento Social/psicología , Mitocondrias , Adenosina Trifosfato/metabolismoRESUMEN
To analyze the academic characteristics and medication rules of traditional Chinese medical master Liu Zu-yi for treating insomnia. Totally 178 cases of insomnia treated by Professor Liu were collected,and the treatment data were input into traditional Chinese medicine inheritance support system( TCMISS) by using data mining methods,such as essential information,frequency statistics of symptoms,syndrome type statistics,extraction of syndrome elements,frequency statistics of drugs; and four properties and five tastes of drugs,distribution of meridians,regularity of prescriptions,new prescription analysis were mined. It was found that the most commonly used drugs( over 100 times) were Albiziae Cortex,Longgu,Polygoni Multiflori Caulis,Ostreae Concha,Ziziphi Spinosae Semen,Crataegi Fructus; the commonly used couplet medicines were Longgu-Ostreae Concha,Ziziphi Spinosae Semen-Polygoni Multiflori Caulis,Ziziphi Spinosae Semen-Albiziae Cortex-Polygoni Multiflori Caulis; and seven new prescriptions in treating insomnia were explored,such as prescriptions containing Hordei Fructus Germinatus,Ziziphi Spinosae Semen,Galli Gigerii Endothelium Corneum,Rehmanniae Radix,Lilii Bulbus. Based on the introduction and discussion of Professor Liu's academic views and characteristics on insomnia treatment and the illustrative evidences added to the typical case list,this paper combines the academic characteristics,data support and typical medical records to verify each other,and objectively summarizes his academic experience for treating insomnia. Treatment shall focus on the primary cause of disease in three aspects; syndrome differentiation shall distinguish between excessive disease and deficient disease; therapy shall reinforce deficiency and reduce diarrhea,regulate the five internal organs,and emphasizes the heart and liver,particularly the liver; medication shall focus on the drugs for calming the mind and protecting the stomach and spleen,which are commonly combined with three types of traditional Chinese medicine with effect in introducing Yangqi( Pinelliae Rhizoma Praeparatum,Prunellae Spica,Polygoni Multiflori Caulis) and restraining Yangqi( Longgu,Ostreae Concha,Ziziphi Spinosae Semen); nursing care focuses on preserving the body and tranquilizing the mind by means of three methods for tranquilizing the mind and three methods for preserving the body.