Safety assessment of a novel marine multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 according to phenotype and whole genome-sequencing analysis

The application of microorganisms as probiotics is limited due to lack of safety evaluation.Here,a novel multi-stress-tolerant yeast Meyerozyma guilliermondii GXDK6 with aroma-producing properties was identified from marine mangrove microorganisms.Its safety and probiotic properties were assessed in accordance with phenotype and whole-genome sequencing analysis.Results showed that the genes and phenotypic expression of related virulence,antibiotic resistance and retroelement were rarely found.Hyphal morphogenesis genes(SIT4,HOG1,SPA2,ERK1,ICL1,CST20,HSP104,TPS1,and RHO1)and phospholipase secretion gene(VPS4)were annotated.True hyphae and phospholipase were absent.Only one retroelement(Tad1-65_BG)was found.Major biogenic amines(BAs)encoding genes were absent,except for spermidine synthase(JA9_002594),spermine synthase(JA9_004690),and tyrosine decarboxylase(inx).The production of single BAs and total BAs was far below the food-defined thresholds.GXDK6 had no resistance to common antifungal drugs.Virulence enzymes,such as gelatinase,DNase,hemolytic,lecithinase,and thrombin were absent.Acute toxicity test with mice demonstrated that GXDK6 is safe.GXDK6 has a good reproduction ability in the simulation gastrointestinal tract.GXDK6 also has a strong antioxidant ability,β-glucosidase,and inulinase activity.To sum up,GXDK6 is considered as a safe probiotic for human consumption and food fermentation.

Action of circulating and infiltrating B cells in the immune microenvironment of colorectal cancer by single-cell sequencing analysis

BACKGROUND The complexity of the immune microenvironment has an impact on the treatment of colorectal cancer(CRC),one of the most prevalent malignancies worldwide.In this study,multi-omics and single-cell sequencing techniques were used to investigate the mechanism of action of circulating and infiltrating B cells in CRC.By revealing the heterogeneity and functional differences of B cells in cancer immunity,we aim to deepen our understanding of immune regulation and provide a scientific basis for the development of more effective cancer treatment strategies.AIM To explore the role of circulating and infiltrating B cell subsets in the immune microenvironment of CRC,explore the potential driving mechanism of B cell development,analyze the interaction between B cells and other immune cells in the immune microenvironment and the functions of communication molecules,and search for possible regulatory pathways to promote the anti-tumor effects of B cells.METHODS A total of 69 paracancer(normal),tumor and peripheral blood samples were collected from 23 patients with CRC from The Cancer Genome Atlas database(https://portal.gdc.cancer.gov/).After the immune cells were sorted by multicolor flow cytometry,the single cell transcriptome and B cell receptor group library were sequenced using the 10X Genomics platform,and the data were analyzed using bioinformatics tools such as Seurat.The differences in the number and function of B cell infiltration between tumor and normal tissue,the interaction between B cell subsets and T cells and myeloid cell subsets,and the transcription factor regulatory network of B cell subsets were explored and analyzed.RESULTS Compared with normal tissue,the infiltrating number of CD20+B cell subsets in tumor tissue increased significantly.Among them,germinal center B cells(GCB)played the most prominent role,with positive clone expansion and heavy chain mutation level increasing,and the trend of differentiation into memory B cells increased.However,the number of plasma cells in the tumor microenvironment decreased significantly,and the plasma cells secreting IgA antibodies decreased most obviously.In addition,compared with the immune microenvironment of normal tissues,GCB cells in tumor tissues became more closely connected with other immune cells such as T cells,and communication molecules that positively regulate immune function were significantly enriched.CONCLUSION The role of GCB in CRC tumor microenvironment is greatly enhanced,and its affinity to tumor antigen is enhanced by its significantly increased heavy chain mutation level.Meanwhile,GCB has enhanced its association with immune cells in the microenvironment,which plays a positive anti-tumor effect.

Fine-mapping and primary analysis of candidate genes associated with seed coat color in mung bean(Vigna radiata L.)

Seed coat color affects the appearance and commodity quality of mung beans(Vigna radiata L.).The substances that affect mung bean seed coat color are mainly flavonoids,which have important medicinal value.Mapping the seed coat color gene in mung beans would facilitate the development of new varieties and improve their value.In this study,an F2 mapping population consisting of 546 plants was constructed using Jilv9(black seed coat)and BIS9805(green seed coat).Using bulk segregated analysis(BSA)sequencing and kompetitive allele-specific PCR(KASP)markers,the candidate region related to seed coat color was finally narrowed to 0.66 Mb on chromosome(Chr.)4 and included eight candidate genes.Combined transcriptome and metabolome analyses showed that three of the eight candidate genes(LOC106758748,LOC106758747,and LOC106759075)were differentially expressed,which may have caused the differences in flavonoid metabolite content between Jilv9 and BIS9805.These findings can provide a research basis for cloning the genes related to seed coat color and accelerate molecular markerassisted selection breeding in mung beans.

Complete Genome Sequencing and Genetic Variation Analysis of Two H9N2 Subtype Avian Influenza Virus Strains

[Objective] The study aimed to investigate the genetic variation characters of entire sequences between two H9N2 subtype avian influenza virus strains and other reference strains.[Method] The entire sequences of 8 genes were obtained by using RT-PCR,and these sequences were analyzed with that of six H9N2 subtype avian influenza isolates in homology comparison and genetic evolution relation.[Result] The results showed that the nucleotide sequence of entire gene of the strain shared 91.1%-95.4% homology with other seven reference strains,and PG08 shared the highest homology 91.3% with C/BJ/1/94;ZD06 shared the highest homology 92.3% with D/HK/Y280/97.HA cleavage sites of two H9N2 subtype avian influenza virus isolated strains were PARSSR/GLF,typical of mildly pathogenic avian influenza virus.[Conclusion] Phylogenetic tree for entire gene of eight strains showed that the genetic relationship was the closest between ZD06 and C/Pak/2/99 strains,which belonged to the Eurasian lineage;PG08 shared the highest homology 91.3% with ZD06,it may be the product of gene rearrangements of other sub-lines.

Genome Sequencing and Phylogenetic Analysis of Three Avian Influenza H9N2 Subtypes in Guangxi

Three isolates of H9N2 Avian Influenza viruses (AIV) were isolated from chickens in Guangxi province. Eight pairs of specific primers were designed and synthesized according to the sequences of H9N2 at GenBank. phylogenetic analysis showed a high degree of homology between the Guangxi isolates and isolates from Guangdong and Jiangsu provinces, suggesting that the Guangxi isolates originated from the same source. However, the eight genes of the three isolates from Guangxi were not in the same sublineages in their respective phylogenetic trees, which suggests that they were products of natural reassortment between H9N2 avian influenza viruses from different sublineages. The 9 nucleotides ACAGAGATA which encode amino acids T, G, I were absent between nucleotide 205 and 214 in the open reading frame of the NA gene in the Guangxi isolates. AIV strains that infect human have, in their HA proteins, leucine at position 226. The analysis of deduced amino acid sequence of HA proteins showed that position 226 of these isolates contained glycine instead of leucine, suggesting that these three isolates differ from H9N2 AIV strains isolated from human infections.

Complete Genome Sequencing and Analysis of Rehmannia Mosaic Virus Isolate from Shanxi Province

Using double-stranded RNA(dsRNA)technology and sequence-independent amplification(SIA),the molecular identification on infected Rehmannia glutinosa in the field with mosaic symptoms was performed and the whole-genome of the Rehmannia mosaic virus(ReMV)Shanxi isolate(ReMV-SX)was sequenced.Sequencing analysis showed that the virus that infected Rehmannia glutinosa was Rehmannia mosaic virus(ReMV).The full-length of the obtained ReMV-SX sequence(GenBank accession no.JX575184)was 6395 nt,containing four open reading frames(ORFs).The sequence homology analysis of the complete nucleotide sequence showed that ReMV-SX was 93.8%-97.0%homologous to ReMV in Tobamovirus subgroup Ⅰ,while only 49.8%-58.9%homologous to the isolates in subgroups Ⅱ and Ⅲ of the same genus.Phylogenetic analysis showed that ReMV-SX and ReMV-Henan formed a separate branch and had the closest genetic relationship.The results laid the foundation for ongoing researches in the taxonomic status and evolution of ReMV and for further investigating the pathogenic mechanism of ReMV infecting Rehmannia glutinosa.

rDNA Sequencing and Preliminary Analysis of Microorganisms from Diseased Edible Fungus Using Non-culture Technology

The metagenomic DNA of disease tissue samples from four kinds of major edible fungus was extracted by CTAB method combined with DNA gel recovery kit. The genomie DNA was amplified by polymerase chain reaction using the universal primers of 16S rDNA and 18S rDNA, and then mone, elonal sequenced after ligated and transformed, rDNA sequences of 20 positive clones were selected randomly from each pair of primers for sequence alignment. The results showed that there were two bacterial diseases and two fungul diseases in the samples, respectively.

Cloning and Sequence Analysis of Interferon γ-2β Full-length cDNA in Cyprinus carpio L.

[Objective] The research aimed to carry out the cloning, identification and sequence analysis of full-length cDNA of carp interferon γ-2β （IFNγ-2β）. [Method] The cDNA library of peripheral blood leucocytes which were separated from carp and stimulated with mitogen was screened by a probe labeled with DIG. The IFNγ- 2β EST sequence was picked out from the constructed cDNA library of peripheral blood leucocyte, and the full length of carp interferon γ-2β was cloned. In addition, the sequence analysis was carried out. [Result] Three positive clones were obtained. Sequence analysis indicated that the sequence had a 119 bp 5’-UTR and a 218 bp 3’-UTR, and the open reading frame （ORF）of this gene was 537 bp which putatively coded 178 amino acids and there were several instable motifs for mRNA （ATTTA） in the 3’-untranslated region. Its homology with IFN from GenBank was up to 97% . Analysis on protein sequence and structure showed that the predicted protein sequence was identified as an IFN family signature. [Conclusion] The research laid the foundation for further studying the expression manner, function characteristic and regulation mechanism of IFNγ-2β in vivo and the action mechanism in the inflammatory reaction, emergency reaction and immune response.

Effects of Compound Probiotics on Growth Performance and Intestinal Flora of Kunming Mice

[Objectives]This study was conducted to investigate the effects of adding compound probiotics on the growth performance and intestinal flora of Kunming mice.[Methods]Twelve healthy 2-week-old Kunming male mice with body weight of(11.09±0.43)g were selected.They were randomly divided into two treatment groups,namely blank control group(NC)and compound probiotics group(CB+LR+BS),with six mice in each group.The two groups were fed with commercial basal diet,and the compound probiotic experimental group was fed with basal diet supplemented with compound probiotics,in which the contents of Clostridium butyricum spores,Lactobacillus reuteri and Bacillus subtilis spores were 1×1010,1×1011 and 1×1010 CUF/kg,respectively.The body weight,feed intake and water intake of mice were counted every 4 d,and the experimental period was 13 d.On the 13 th day,the cecal contents of the mice were collected for analysis.[Results]There was no significant change in body weight and feed intake when compound probiotics were added to the diet.However,the addition of compound probiotics reduced the abundance of harmful bacteria such as Escherichia coli,urease-negative Helicobacter typhlonius and Salmonella enterica,while increasing the abundance of beneficial bacteria such as Anaerostipes hadrus,and the contents of IgG and IgM increased significantly(P<0.05).[Conclusions]In summary,the addition of compound probiotics could significantly improve the structure of intestinal microbial flora,increase the quantity of beneficial bacteria,reduce the quantity of harmful bacteria,and improve the immune function of mice.

Cloning and Sequence Analysis of Actin Gene from Rehmannia glutinosa

[ Objective ] The aim of this study is to clone and analyze the actin gene from Rehmannia glutinosa. [ Method ] Degenerate primers were designed according to the conserved regions of actin sequences of Rehmannia glutinosa and its similar species, RT-PCR was next conducted to amplify the actin gene from Rehmannia glutinosa. [ Result] The amplified fragment is 724 bp and correspondingly 240 amino acids. The BLAST results indicate that the homology between the amplified fragment and other higher plants for aetin gene sequences and amino acid are more than 80% and 90%, respectively, suggesting that the amplified fragment is the actin gene of Rehmannia glutinosa. [ Conclusion] Phylogenetic analysis shows that the actin gene of Rehmannia glutinosa has an intimate genetic relationship with actin7 gene of Nicotiana tabacum.

Sequence Analysis of Polymorphic Fragments in the Third Intron of Porcine H-FABP Gene

[ Objective] The aim of this study was to provide a theoretical basis for exploring the major genes affecting intramuscular fat （IMF） deposition. [Method] Taking 383 pigs from five breeds including Mashen Pig, Large White Pig, Landrace, Duroc and Shanxi White Pig as the experimental animals, polymorphisms of partial fragments in the third intron of porcine H-FABP gene were detected by PCR-SSCP method, and then the polymorphic fragments were sequenced. [ Result] Two alleles, designated as A and B, were found at the locus 346 in the third intron of porcine H-FABP gene, and the mutation was caused by a A→G substitution. [ Conclusion] A polymorphic locus was discovered in the third intron of porcine H-FABP gene in this experiment, laying a foundation for the further study on the relationship between H-FABP gene and IMF content.

cDNA Cloning and Sequencing of Squalene Synthase of Artemisa apiacea

[Objective] cDNA from squalene synthase was cloned and sequenced.[Method] A pair of specific primers was designed according to the cDNA gene sequence of squalene synthase published in GenBank.Total RNA was extracted from the cell of Artemisia apiacea.The genes of squalene synthase were amplified by using RT-PCR.It was connected with pMD19-T vector and the cloned fragment sequences were analyzed.[Result] SS gene with the whole length of 1 257 bp was amplified and the fragment encoded 418 amino acids.The homo...

Analysis on Heredity and Variation of the ORF_5 Gene of Prevalence Strains Porcine Reproductive and Respiratory Syndrome Virus

[ Objective] The aim was to analyze the reason and epidemic trend of PRRSV, and provide theoretical basis for preventing and controlling PRRS. [Methed]According to the sequence of ATCC VR-2332 strain porcine reproductive and respiratory syndrome virus published by the GenBank, the primers were designed and synthesized. ORF5 gene sequences of seven prevalence strains were amplified by RT-PCR. The sequences of ORF5 genes were analyzed by DNAStar and compared with those of ATCC VR-2332, CH-1 a, B J-4, LV-M96262 and MLV vaccine strains, phylogenetic tree among isolates was analyzed. [Result] Analysis of nucleotide sequence showed that the homology was 88.1% - 98.8%, 89.9% -95.2%, 85.6% -98.7% between ORF5 genes of seven prevalence strains and VR-2332, CH-1a, BJ-4, and the homology was 54.7% -56.9% between ORF5 genes and LV. Analysis of amino acid sequence showed that the homology was 88.1% -96.8%, 88.1% - 94.5%, 86.1% -96.5% between ORF5 genes of seven prevalence strains and VR-2332, CH-1a, bBJ-4, the homology was 54.7% -56.2% between the ORF5 genes and LV.[ Conclusion] The variation of prevalence strains was great in the ORF5 gene region, the homology of ORF5 gene sequence was higher and genetic relationship was nearer during prevalence strains in the same region, or was far in different regions.

Molecular Cloning and Sequence Analysis of Class Ⅱ Chitinase Gene in Leymus chinensis

[ Objective] The aim of this study was to clone Class Ⅱ chitinase gene in Leymus chinensis grown in saline land in Heilongjiang Province and analyze its sequence, which provided a foundation for further study on the biological function and application of chitinasa gene. [ Method] cDNA library of Leymus chinensis leaves were constructed, and its DNA sequence was determined or analyzed, while the homology of chitinasa gene and amino acid sequence was compared with that in GenBank. [ Result] One full length cDNA fragment with length of 996 bp was cloned from cDNA library of Leymus chinensis leaves. The length of ORF was 768 bp encoding 225 amino acids （GenBank accession number： EU344908）. The encoding products lacked CBD and C-terminal extension region from the view of structure, but had structural characters of Class Ⅱ chitinase gene, which indicated that amino acid sequence had high homology compared with Class Ⅱ chitinase gene of rye and wheat. The constructed recombinant vector pQE-LcChi2 could express a protein of 27 kD through induction, which was consistent with the deduced encoding product of pQE-LcChi2 gene. [ Conclusion] LcChl2 gene is an expression gene, which can express in E. coll.

Determination and Analysis of Mitochondrial ND2 Gene Sequence of Anas platyrhynchos

[Objective] The study was to analyze the phylogenesis of Anas platyrhynchos. [Method] Complete sequence of mitochondrial ND2 gene of 4 Anas platyrhynchos was determined by direct DNA sequencing based on PCR products. Combined with ND2 gene sequences of the Anas Linnaeus accessed in GenBank, phylogenetic tree was constructed by Neighbor-joining and maximum parsimony methods. [Result] The ND2 gene sequences of 4 Anas platyrhynchos were identical(1 041 bp in length; the nucleotide contents of A, G, T, and C were 28.91%, 13.35%, 20.75% and 36.98% respectively; A+T content approximated to that of C+G). Sequences of ND2 gene of mallard were same as spotbill duck, and had high homology with others. The phylogenetic trees indicated mallard and spotbilled duck were close in genetic relationship, both shared a haplotype; then Philippine duck, green-winged teal and northern pintail fell into branch ''A". [Conclusion] The domestic duck may be domesticated from mallard and spotbilled duck.

Cloning and Sequence Analysis of 16S rRNA and COI Gene in Mitochondrial DNA of Scortum barcoo

[Objective] The aim was to provide molecular biological basis for the researches on the genetic resources,genetic relationship among species and phyletic evolution of S.barcoo.[Method] PCR amplification and sequencing were used to study the 16S rRNA and COI gene fragments.[Result] As for 16S rRNA gene fragments,nucleotide sequences of 791 bp were obtained,and the A,T,G and C contents in this fragment were 31.6%,21.4%,20.4% and 26.7%respectively.As for the COI gene fragments,the size was 631 bp and the A,T,G And C contents were 27.7%,23.6%,29.8% and 18.9% respectively.Among these two gene fragments,the content of GC was lower than AT,and AT/GC of these two fragments was 1.13 and 1.05 respectively.[Conclusion] The genetic characteristics of gene fragments of 16S rRNA and COI of S.barcoo suggested that the variation in the same species was relatively low.The sequences of 16S rRNA gene in three samples the same,while the sequences of COI gene was also the same,indicating that these two gene of S.barcoo were conservative.

Sequence Analysis of HA Genes from Three H9N2 Subtype Avian Influenza Viruses

[ Objective] The study aimed to understand the genetic characters of H9N2 subtype avian influenza viruses isolated in Belling area. [ Method] HA genes of three H9N2 subtype avian influenza viruses A/Chicken/Beijing/xu/00, A/Chicken/Beijing/bei/00 and A/Chicken/Beijing/ liu/00 were amplified by RT-PCR and then sequenced. [ Result] The results of phylogenetic analysis showed that A/Chicken/Beijing/xu/00, A/ Chicken/Beijing/bei/00 and A/Chicken/Beijing/liu/00 shared the nucleotide homologies of 84.8% （ Dk/HK/Y439/97 ） -98.0% （ Ck/GX17/00 ）, 85.1% （Dk/HK/Y439/97） - 99.1% （ Ck/GXl 7/00）, 90.7% （ Ck/BJ/3/01 ） - 99.1% （Ck/GX17/00） with the isolates from Hongkong and other are- as of Chinese Mainland respectively. At the same time, the analysis of amino acid indicated that the three isolates belonged to low pathogenic H9N2 isolates of avian origin. The 226^th amino acid of them were L （ Leu）, suggesting their high binding affinity to human cells. There were seven glyco- sylation sites in HA protein, five from HA1 and two from HA2. [ Cenclusien] By analysis at molecular level, it could be concluded that A/Chicken/ Beijing/xu/00, A/Chicken/Beijing/bei/00 and A/Chicken/Beijing/liu/00 were low pathogenic H9N2 isolates of avian origin.

Isolation of Rice EPSP Synthase cDNA and Its Sequence Analysis and Copy Number Determination

In order to isolate the total cDNA of rice (Oryza sativa L.) epsps gene, RT-PCR was carried out with template of rice first-strand cDNA and primers designed according to rice EPSP synthase genomic sequence obtained in previous study. A 1 585-bp cDNA fragment was amplified and cloned. The 1 585-bp cDNA contains an open reading frame (ORF) comprising of 1 533 nucleotides (nt) which encodes a 511 residue polypepetides, including 67 amino acids chloroplast transit peptide and 444 amino acids EPSP synthase mature peptide. A comparison between the EPSP synthase of different sources indicates that the mature peptide shows more than 51% identity except for the fungi EPSP synthase and the transit peptide shows considerably less sequence conservation. The copy number of rice epsps gene is estimated to be one copy per haploid rice genome using southern blot. RT-PCR indicated that rice epsps gene is expressed in rice leaves, endosperms and roots and has the highest expression level in leaves.

Sequence Analysis of ITS Region of rDNA of Alternaria Nees. from Some Areas of China

[Objective] The study aimed to identify Alternaria Nees from some areas of China at molecular level by analyzing the rDNA ITS sequence. [ Method ] The DNA sequences coding for the 5.8S rDNA and the flanking internal transcribed spacers （ ITS1 and ITS2） were amplified by PCR with universal primers ITS4 and ITS5 and subsequently sequenced for 34 Alternaria isolates from different areas of China. [Result] Sequences analysis showed that 5.8S rDNA was 159 bp and no variation in tested 34 isolates. There had variables sites in ITS. The isolates that had same sequences as A. tenuissima or A. alternata all put up eurytopicity to area and host. The variables sites of the isolates showed the diver- sity of Alternaria in the hosts of Oleaceae, Rosaceae and Solanaceae. At the same time that ITS could not clearly separated the isolates was indicated. The results indicated that the phylogenetic relationship were not closely related to the geographical origin and hosts of these isolates. [ Conclusion] The sequence analysis of ITS region could provide theory basis for the identification of Alternaria Nees..

Cloning and Sequence Analysis of Lactate Dehydrogenase C(LDH-C)Gene from Black-lipped Pika in Western Sichuan Plateau

[Objective] The aim was to lay a foundation for research of contraceptive rodenticide with LDH-C4 as target protein. [ Method] EST sequence of LDH-C gene from black-lipped pika was cloned by PCR with degenerate primers; then the full length open reading frame （ORF） and 3＇UTR sequence were cloned by RACE technique. [ Result] The full length cDNA was 1 498 bp containing an ORF of 996 bp and a 3＇UTR of 486 bp. The ORF encoded a polypeptide of 332 amino acids. The alignment of LDH-C gene ORF nucleotide sequences from different species showed that the gene was conserved even between large taxons. The phylogenic tree showed that black-lipped pika LDH-C was closer to prima- tes and artiodactyla than to rodents. [Conclusion] cDNA sequence of LDH-C gene from black-lipped pika was cloned successfully.