Comparative and phylogenetic analysis of the complete chloroplast genomes of 10 Artemisia selengensis resources based on high-throughput sequencing.

BACKGROUND: Artemisia selengensis, classified within the genus Artemisia of the Asteraceae family, is a perennial herb recognized for its dual utility in culinary and medicinal domains. There are few studies on the chloroplast genome of A. selengensis, and the phylogeographic classification is vague, which makes phylogenetic analysis and evolutionary studies very difficult. RESULTS: The chloroplast genomes of 10 A. selengensis in this study were highly conserved in terms of gene content, gene order, and gene intron number. The genome lengths ranged from 151,148 to 151,257 bp and were typical of a quadripartite structure with a total GC content of approximately 37.5%. The chloroplast genomes of all species encode 133 genes, including 88 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Due to the contraction and expansion of the inverted repeats (IR), the overlap of ycf1 and ndhF genes occurred at the inverted repeats B (IRB) and short single copy sequence (SSC) boundaries. According to a codon use study, the frequent base in the chloroplast genome of A. selengensis' third codon position was A/T. The number of SSR repeats was 42-44, most of which were single nucleotide A/T repeats. Sequence alignment analysis of the chloroplast genome showed that variable regions were mainly distributed in single copy regions, nucleotide diversity values of 0 to 0.009 were calculated by sliding window analysis, 8 mutation hotspot regions were detected, and coding regions were more conserved than non-coding regions. Analysis of non-synonymous substitution (Ka) and synonymous substitution (Ks) revealed that accD, rps12, petB, and atpF genes were affected by positive selection and no genes were affected by neutral selection. Based on the findings of the phylogenetic analysis, Artemisia selengensis was sister to the genus Artemisia Chrysanthemum and formed a monophyletic group with other Artemisia genera. CONCLUSIONS: In this research, the present study systematically compared the chloroplast genomic features of A. selengensis and provided important information for the study of the chloroplast genome of A. selengensis and the evolutionary relationships among Asteraceae species.

Enhanced bioelectrochemical performance of microbial fuel cell with titanium dioxide-attached dual metal organic frameworks grown on zinc aluminum - layered double hydroxide as cathode catalyst.

In this study, a three-step distributed feeding method was used to prepare TiO2-attached dual CoZn-metal organic frameworks growing on ZnAl-layered double hydroxide (TiO2@ZIF-67/ZIF-8@ZnAl-LDH) as cathode catalyst of microbial fuel cell (MFC). The composite material was a composite core-shell structure constructed by multi-layer coating with sheet-like ZnAl-LDH as the base, dual MOFs as the magnetic core and TiO2 as the rough surface. The composite material had crystal planes (009), (110), (101) interface. The rough surface, core-shell core and polyhedral structure of TiO2@ZIF-67/ZIF-8@ZnAl-LDH were observed. The complete distribution of Ti, Zn, Al, and Co in the material was observed and offered active sites. The contents of Ti (15.97 %), Al (5.53 %), Na (5.04 %), N (3.52%), Zn (1.47 %) were found out. TiO2@ZIF-67/ZIF-8@ZnAl-LDH was excellent in electrochemical activity and the maximum power density was 409.6 mW/m2, the stable continuous output voltage was 538.4 mV for 8 d.

Improving oxygen reduction reaction of microbial fuel cell by titanium dioxide attaching to dual metal organic frameworks as cathode.

In this study, a two-step simple distributed feeding method was used to prepare the core-shell nanocomposite dual metal organic frameworks (D-MOFs, TiO2@ZIF-67/ZIF-8). There were three obvious peaks (011), (112), (222) interface in D-MOFs core, which fully showed that ZIF-67/ZIF-8 crystal core was successfully synthesized. The morphology of composite material was core-shell structure with a rough surface, and Ti, Co, Zn, Al were uniformly distributed on the surface. TiO2@ZIF-67/ZIF-8 also had excellent electrochemical activity and the maximum power density of TiO2@ZIF-67/ZIF-8 microbial fuel cell (MFC) was 341.506 mW/m2, which was 1.30 times of ZIF-67/ZIF-8-MFC (262.144 mW/m2) and 2.07 times of ZIF-67-MFC (164.836 mW/m2). And the continuous output voltage of TiO2@ZIF-67/ZIF-8-MFC was 413.43 mV, which could maintain stable voltage output for 8.3 days. D-MOFs as the core of composites ensured the integrity, stability and high activity of materials; Rough TiO2 as the surface of the material provided surface area and reaction center.

The karyotype, genome survey, and assembly of Mud artemisia (Artemisia selengensis).

BACKGROUND: Artemisia selengensis is traditional Chinese medicine and phytochemical analysis indicated that A. selengensis contains essential oils, fatty acids and phenolic acids. The lack of reference genomic information may lead to tardiness in molecular biology research of A. selengensis. METHOD AND RESULTS: Karyotype analysis, genome survey, and genome assembly was employed to acquire information on the genome structure of A. selengensis. The chromosome number is 2n = 2x = 36, karyotype formula is 28 m + 8Sm, karyotype asymmetry coefficient is 58.8%, and karyotypes were symmetric to Stebbins' type 2A. Besides, the flow cytometry findings reported that the mean peak value of fluorescent intensity is 1,170,677, 2C DNA content is 12 pg and the genome size was estimated to be approximately 5.87 Gb. Furthermore, the genome survey generates 341,478,078 clean reads, unfortunately, after K-mer analysis, no significant peak can be observed, the heterozygosity, repetitive rate and genome size was unable to estimated. It is speculated that this phenomenon might be due to the complexity of genome structure. 37,266 contigs are preliminary assembled with Oxford Nanopore Technology (ONT) sequencing, totaling 804 Mb and GC content was 34.08%. The total length is 804,475,881 bp, N50 is 29,624 bp, and the largest contig length is 239,792 bp. CONCLUSION: This study reveals the preliminary information of genome size of A. selengensis. These findings may provide supportive information for sequencing and assembly of whole-genome sequencing and encourage the progress of functional gene discovery, genetic improvement, evolutionary study, and structural studies of A. selengensis.

Improved electrochemical performances by Ni-catecholate-based metal organic framework grown on NiCoAl-layered double hydroxide/multi-wall carbon nanotubes as cathode catalyst in microbial fuel cells.

In this study, a simple two-step hydrothermal method was used to prepare the cathode catalyst of the microbial fuel cell (MFC). NiCoAl- layered double hydroxide (LDH) nanosheets were grown vertically on multi-wall carbon nanotubes (MWCNTs) in situ; Ni-catecholate-based metal organic framework (Ni-CAT MOF) were modified on the surface of the nanosheets. The maximum output voltage of Ni-CAT/NiCoAl-LDH/MWCNTs was 475 mV, the maximum stabilization time was 8 d, the maximum output power was 448.5 ± 12.0 mW/m2, which was 1.03 times that of NiCoAl-LDH/MWCNT-MFC (433.5 ± 14.8 mW/m2) and 1.35 times of NiCoAl-LDH- MFC (329.9 ± 2.9 mW/m2). The layer structure of LDH, conductivity of Ni-CAT and MWCNT improved the flow efficiency of ions between layers and effectively reduced transmission resistance, and these have effectively enhanced the cycle stability and power generation efficiency of the electrode.