In vitro bio-corrosion behaviors of biodegradable AZ31B magnesium alloy under static stresses of different forms and magnitudes

Biomedical degradable materials would be subjected to different degrees and forms of static stress after being implanted in the human body.In this work,the biocorrosion behaviors of AZ31B magnesium alloy under different stress forms with different magnitudes(20~150MPa)were studied.It was found that the corrosion behaviors at stressed conditions were severer than those at unstressed conditions and corrosion rates were obviously accelerated.The biocorrosion behaviors are more sensitive to the effects of tensile loads than to compressive loads.A biocorrosion numerical model on the degradation process of Mg alloy under static loads was established.The corrosion current density(i_(corr))of Mg alloy and the applied static stress(σ)matches a linear relationship of ln i_(corr)~σwell during the early stage(within 24 hrs)while deviated gradually in the latter period of corrosion.This work could provide a guidance and theoretical reference for further researches on the biocorrosion behaviors and practical clinical applications of the biomedical materials subjected to physiological loads.

Isolation and identification of Starmerella davenportii strain Do18 and its application in black tea beverage fermentation

The objective of this study was to isolate and identify a yeast strain from the kombucha beverage and evaluate its potential as a novel starter in beverage fermentation in vitro.Starmerella davenportii Do18 was characterized for its cholesterol reduction;growth at different conditions such as temperatures(25,30,37 and 42◦C),low pH(1.2,1.5,2.03.0,and 7.0),bile salts(0%,0.25%,0.5%,1%and 2%)high-sucrose stress(2%,10%,20%,40%and 60%);and in-vitro survival in gastric and intestinal environments.Results showed that the yeast strain has a cholesterol-lowering capacity of 45%±2%,grew at temperature of 37◦C and is resistant to pH 1.5,2%bile and 40%sucrose solution,could survive in simulated gastric and intestinal environments.The physicochemical characteristics of the fermented beverages were also evaluated,which indicated that the yeast has pH reduction capacity and can produce organic acids and volatile compound such as 2-phenylethanol.Furthermore,the fermented beverage also has high total phenolics and flavonoids content and showed great antioxidant and antimicrobial activities.Therefore,the findings of this research provide strong evidence that S.davenportii Do18 has good fermentation properties,can be a potential starter in food and beverage fermentation.

Genomic,transcriptomic,and epigenomic analysis of a medicinal snake,Bungarus multicinctus,to provides insights into the origin of Elapidae neurotoxins

The many-banded krait,Bungarus multicinctus,has been recorded as the animal resource of JinQianBaiHuaShe in the Chinese Pharmacopoeia.Characterization of its venoms classified chief phyla of modern animal neurotoxins.However,the evolutionary origin and diversification of its neurotoxins as well as biosynthesis of its active compounds remain largely unknown due to the lack of its high-quality genome.Here,we present the 1.58 Gbp genome of B.multicinctus assembled into 18 chromosomes with contig/scaffold N50 of 7.53 Mbp/149.8 Mbp.Major bungarotoxin-coding genes were clustered within genome by family and found to be associated with ancient local duplications.The truncation of glycosylphosphatidylinositol anchor in the 3'-terminal of a LY6E paralog released modern three-finger toxins(3FTxs)from membrane tethering before the Colubroidea divergence.Subsequent expansion and mutations diversified and recruited these 3FTxs.After the cobra/krait divergence,the modern unit-B ofβ-bungarotoxin emerged with an extra cysteine residue.A subsequent point substitution in unit-A enabled theβ-bungarotoxin covalent linkage.The B.multicinctus gene expression,chromatin topological organization,and histone modification characteristics were featured by transcriptome,proteome,chromatin conformation capture sequencing,and ChIP-seq.The results highlighted that venom production was under a sophisticated regulation.Our findings provide new insights into snake neurotoxin research,meanwhile will facilitate antivenom development,toxin-driven drug discovery and the quality control of JinQianBaiHuaShe.

Allele-aware chromosome-level genome assembly of Artemisia annua reveals the correlation between ADS expansion and artemisinin yield

Artemisia annua is the major natural source of artemisinin,an anti-malarial medicine commonly used worldwide.Here,we present chromosome-level haploid maps for two A.annua strains with different artemisinin contents to explore the relationships between genomic organization and artemisinin production.High-fidelity sequencing,optical mapping,and chromatin conformation capture sequencing were used to assemble the heterogeneous and repetitive genome and resolve the haplotypes of A.annua.Approximately 5o,ooo genes were annotated for each haplotype genome,and a triplication event that occurred approximately 58.12million years ago was examined for the first time in this species.A total of 3,903,467-5,193,414 variants(SNPs,indels,and structural variants)were identified in the 1.5-Gb genome during pairwise comparison between haplotypes,consistent with the high heterozygosity of this species.Genomic analyses revealed a correlation between artemisinin concents and the copy number of amorpha-4,11-dienes ynthasegenes.This correlation was further confirmed by resequencing of 36A.annua samples with varied artemisinin contents.Circular consensus sequencing of transcripts facilitated the detection of paralog expression.Collectively,our study provides chromosome-level allele-aware genome assemblies for two A.annua strains and new insights into the biosynthesis of artemisinin and its regulation,which will contribute to conquering malaria worldwide.

50th anniversary of artemisinin:From the discovery to allele-aware genome assembly of Artemisia annua

Over the past half century,the fight against malaria has been a resounding success mainlydue to thediscoveryof artemisinin.According to the World Health Organization(WHO),morbidity and mortality due to malaria have been cut by half since the promotion of artemisinin-based combination therapy(WHO,2020).

The influence of alternating cyclic dynamic loads with different low frequencies on the bio-corrosion behaviors of AZ31B magnesium alloy in vitro

The real physiological environment of human body is complicated with different degrees and forms of dynamic loads applied to implanted medical devices due to the daily activities of the patients,which would have impacts on the degradation behaviors of magnesium alloy implants.In this work,the bio-corrosion behaviors of AZ31B magnesium alloy under alternating cyclic dynamic loads with different low frequencies(0.1-2.5 Hz)were specially investigated.It was found that the bio-degradation performances under external dynamic stressed conditions were much severer than those under unstressed conditions and static loads.The corrosion rates were generally accelerated as the rise of cyclic frequency.Hereby a numerical model for the degradation process of Mg alloy was established.The corrosion current density icorr of Mg alloy and the applied loading frequency f matches a linear relationship of ln icorr∝f,which is the result of interactions between the cyclic alternating load and corrosive environment.This work could provide a theoretical reference and an experimental basis for further researches on the biodegradation behaviors of biomedical materials under dynamic conditions.