Radioprotective effects of the expression of FLT3 ligand regulated by Egr-1 regulated element on radiation injury of SCID mice

Objective: In order to explore the radioprotective effects of the expression of hematopoietic growth factors regulated by radio-inducible promoter on radiation injury. Methods:The human FL (Flt3 ligand) cDNA and EGFP (enhanced green fluorescent protein) cDNA were linked together with IRES and then inserted into the eukaryotic expression vector pCI-Egr, which was constructed by substituting CMV promoter in pCIneo with the Egr-1 promoter (Egr-EF). The vector was transferred into human bone marrow stromal ...

Genomic imbalance modulates transposable element expression in maize

Genomic imbalance refers to the more severe phenotypic consequences of changing part of a chromosome compared with the whole genome set.Previous genome imbalance studies in maize have identified prevalent inverse modulation of genes on the unvaried chromosomes(trans)with both the addition or subtraction of chromosome arms.Transposable elements(TEs)comprise a substantial fraction of the genome,and their reaction to genomic imbalance is therefore of interest.Here,we analyzed TE expression using RNA-seq data of aneuploidy and ploidy series and found that most aneuploidies showed an inverse modulation of TEs,but reductions in monosomy and increases in disomy and trisomy were also common.By contrast,the ploidy series showed little TE modulation.The modulation of TEs and genes in the same experimental group were compared,and TEs showed greater modulation than genes,especially in disomy.Class Ⅰ and Ⅱ TEs were differentially modulated in most aneuploidies,and some superfamilies in each TE class also showed differential modulation.Finally,the significantly upregulated TEs in three disomies(TB-7Lb,TB9Lc,and TB-10L19)did not increase the proportion of adjacent gene expression when compared with non-differentially expressed TEs,indicating that modulations of TEs do not compound the effect on genes.These results suggest that the prevalent inverse TE modulation in aneuploidy results from stoichiometric upset of the regulatory machinery used by TEs,similar to the response of core genes to genomic imbalance.

Recent advances in keratinase production via protein engineering,breeding,and fermentation

The gene editing and synthetic biological tools have led to the implementation of diverse metabolic engineering approaches to enhance the production of specific enzymes.Microbial keratinases can convert keratin wastes into valuable compounds for mankind.Since the market for keratinases cannot be satisfied by production from wild hosts,it is obligatory to develop hosts with high keratinase yields.The intention of this review is to evaluate microbial keratinase advancement through protein engineering,breeding techniques,and fermentation optimization.The main aim of protein engineering is to improve the heat resistance ability and catalytic activity of keratinases by employing mutagenesis methods.Moreover,modifying the expression elements and host engineering are also two unique ways to augment the keratinase yield.Intending to accelerate the production of modified keratinase,this review attempts to highlight the optimization of expression elements,such as promoter engineering,UTR,signal peptide,and codon optimization.Moreover,the approaches of host engineering including strengthening precursor supply,membrane surface engineering,and optimization of secretion pathways were also explained here.Furthermore,it is also essential to optimize the medium composition and fermentation condition for high keratinase yield.This review also addressed the present advancements,difficulties,and tendencies in the field of microbial keratinase production,along with its potential.

Enhanced production of poly-γ-glutamic acid via optimizing the expression cassette of Vitreoscilla hemoglobin in Bacillus licheniformis

Poly-γ-glutamic acid(γ-PGA)is a natural polymer with various applications,and its high-viscosity hinders ox-ygen transmission and improvement of synthesis level.Vitreoscilla hemoglobin(VHB)has been introduced into various hosts as oxygen carrier,however,its expression strength and contact efficiency with oxygen hindered efficient oxygen transfer and metabolite synthesis.Here,we want to optimize the expression cassette of VHB for γ-PGA production.Firstly,our results implied that γ-PGA yields were enhanced when introducing twin-arginine translocation(Tat)signal peptides(SP_(YwbN),SP_(PhoD) and SP_(TorA))into VHB expression cassette,and the best per-formance was attained by SP YwbN from Bacillus subtilis,theγ-PGA yield of which was 18.53% higher than that of control strain,and intracellular ATP content and oxygen transfer coefficient(K_(L)a)were increased by 29.71% and 73.12%,respectively,indicating that VHB mediated by SP YwbN benefited oxygen transfer and ATP generation forγ-PGA synthesis.Furthermore,four promoters were screened,and P vgb was proven as the more suitable promoter for VHB expression andγ-PGA synthesis,andγ-PGA yield of attaining strain WX/pPvgb-YwbN-Vgb was further increased to 40.59 g/L by 10.18%.Finally,WX/pPvgb-YwbN-Vgb was cultivated in 3 L fermentor for fed-batch fermentation,and 46.39 g/Lγ-PGA was attained by glucose feeding,increased by 49.26%compared with the initial yield(31.01 g/L).Taken together,this study has attained an efficient VHB expression cassette for oxygen transfer andγ-PGA synthesis,which could also be applied in the production of other metabolites.