Listeria monocytogenes serotype 4b strains account for about 40% of sporadic cases and many epidemics of listeriosis. Mutations in a chromosomal locus resulted in loss of reactivity with all three monoclonal antibodies (MAbs) which were specific to serotype 4b and the closely related serotypes 4d and 4e. Here we show that this locus contains a serotype 4b-4d-4e-specific gene cassette (3,071 bp) which consists of two genes, gltA and gltB, and is flanked by palindromic sequences (51 and 44 nucleotides). Complete loss of reactivity with the three serotype-specific MAbs resulted from insertional inactivation of either gltA or gltB. The gltA and gltB mutants were characterized by loss and severe reduction, respectively, of glucose in the teichoic acid, whereas galactose, the other serotype-specific sugar substituent in the teichoic acid, was not affected. Within L. monocytogenes, only strains of serotypes 4b, 4d, and 4e harbored the gltA-gltB cassette, whereas coding sequences on either side of the cassette were conserved among all serotypes. Comparative genomic analysis of a serotype 1/2b strain showed that the 3,071-bp gltA-gltB cassette was replaced by a much shorter (528-bp) and unrelated region, flanked by inverted repeats similar to their counterparts in serotype 4b. These findings indicate that in the evolution of different serotypes of L. monocytogenes, this site in the genome has become occupied by serotypespecific sequences which, in the case of serotype 4b, are essential for expression of serotype-specific surface antigens and presence of glucose substituents in the teichoic acids in the cell wall.

Listeria monocytogenes serotype 4b has been implicated in numerous food-borne epidemics and in a substantial fraction of sporadic listeriosis. A unique lineage of the nonpathogenic species Listeria innocua was found to express teichoic acid-associated surface antigens that were otherwise expressed only by L. monocytogenes of serotype 4b and the rare serotypes 4d and 4e. These L. innocua strains were also found to harbor sequences homologous to the gene gtcA, which has been shown to be essential for teichoic acid glycosylation in L. monocytogenes serotype 4b. Transposon mutagenesis and genetic studies revealed that the gtcA gene identified in this lineage of L. innocua was functional in serotype 4b-like glycosylation of the teichoic acids of these organisms. The genomic organization of the gtcA region was conserved between this lineage of L. innocua and L. monocytogenes serotype 4b. Our data are in agreement with the hypothesis that, in this lineage of L. innocua, gtcA was acquired by lateral transfer from L. monocytogenes serogroup 4. The high degree of nucleotide sequence conservation in the gtcA sequences suggests that such transfer was relatively recent. Transfer events of this type may alter the surface antigenic properties of L. innocua and may eventually lead to evolution of novel pathogenic lineages through additional acquisition of genes from virulent listeriae.Wall teichoic acids are predominant constituents of the cell envelope of Listeria monocytogenes and other gram-positive bacteria. In Listeria, pronounced diversity in teichoic acid structure and antigenicity is conferred by glycosidic substitutions of the ribitol phosphate units (6,7,12,27,28). Such substitutions differ among different listerial serotypes. In the pathogenic species L. monocytogenes (the only Listeria species pathogenic to humans), serotype 4b strains are unique in bearing both galactose and glucose substituents on the N-acetylglucosamine (GlcNAc) of teichoic acid (6,27). This is of interest, as serotype 4b accounts for a large fraction of sporadic infections due to L. monocytogenes and for almost all confirmed food-borne outbreaks of listeriosis (5, 13, 21).The genetic basis for teichoic acid glycosylation in L. monocytogenes and other species of Listeria remains poorly understood. Recently we described the serogroup 4-specific gene gtcA, which was essential for decoration of cell wall teichoic acids of L. monocytogenes serotype 4b with galactose and glucose. Mutants with insertional mutations in gtcA lacked galactose and had only trace levels of glucose in the teichoic acid (20). Several findings suggest that teichoic acid glycosylations may serve important ecological and virulence functions in L. monocytogenes: glycosylation-impaired mutants of serotype 1/2a and 4b were found to be resistant to serotype-specific phages (26; N. Promadej, F. Fiedler, and S. Kathariou, unpublished data), and gtcA mutants of serotype 4b are impaired in certain aspects of the host cell-pathogen interaction, including invasion of fibroblasts (Promadej...

Apolipoprotein E (APOE) ε4 allele and sigma-1 receptor (SIGMAR1) c.5C (Q2P) polymorphisms have been acknowledged as risk factors for developing Alzheimer's disease (AD). However, whether these polymorphisms influence the disease process is unclear. Therefore, two cohorts with a clinical diagnosis of AD were recruited, a postmortem confirmed Australian cohort (82 cases) from the Australian Brain Bank Network, and a Chinese cohort with detailed clinical assessments recruited through an epidemiology study in Shanghai and through the neurology department outpatients clinic of Shanghai Ruijin Hospital (330 cases). SIGMAR1 Q2P and APOE genotyping was performed on all cases. Dementia severity in the Chinese cohort was assessed using MMSE scores, and the stages of senile plaques and neurofibrillary tangles (NFT) assessed in the Australian cohort. Associations between SIGMAR1 Q2P and APOE genotypes and disease severity were assessed using SPSS. Results confirmed that APOE 4 allele associated with increased NFT stages and cognitive decline, with carriers with one APOE ε2 or ε3 allele often having better clinical outcomes compared to carriers with none or two ε2 or ε3 alleles respectively. SIGMAR1 c.5C polymorphism alone did not associate with MMSE score variability in Chinese or with pathological stages in Caucasians. However, the association studies revealed a significant genetic interaction between the APOE ε4 allele and SIGMAR1 2P carriers in both populations, i.e., in APOE non ε4 allele carriers, SIGMAR1 2P variant had increased cognitive dysfunction and more advanced stages of NFT. Our data demonstrate that SIGMAR1 and APOE interact to influence AD severity across ethnic populations.

Mutation detection in the guanosine triphosphate cyclohydrolase I gene (GCH1) was performed from 4 female patients with dopa-responsive dystonia (DRD). DNA sequencing revealed the presence of four novel mutations including c.2T>C(M1T), c.239G>A(S80N), c.245T>C(L82P), and IVS5+3 del AAGT. These four mutations were not found in 100 genetically unrelated healthy controls with the same ethnic background band. In all 3 childhood-onset patients, DRD started in the legs, and missense mutations were located in the coding region of GCH1. Deletion mutation in the fifth exon-intron boundary of GCH1 was detected in the adult-onset patient. Although the data presented here do not provide sufficient evidence to establish a genotype-phenotype correlation of DRD, it is important to know the clinic features and genetic defects of DRD patients, which will help prenatal diagnosis, early diagnosis, evaluate the prognosis, and facilitate causal therapy with levodopa.

No abstract

Baisuifang Granule is an effective Chinese medicine for treating cognitive malfunction after cerebral infarction.

Multiple-target plasmid DNA reference materials have been generated and utilized as good substitutes of matrix-based reference materials in the analysis of genetically modified organisms (GMOs). Herein, we report the construction of one multiple-target plasmid reference molecule, pCAN, which harbors eight GM canola event-specific sequences (RF1, RF2, MS1, MS8, Topas 19/2, Oxy235, RT73, and T45) and a partial sequence of the canola endogenous reference gene PEP. The applicability of this plasmid reference material in qualitative and quantitative PCR assays of the eight GM canola events was evaluated, including the analysis of specificity, limit of detection (LOD), limit of quantification (LOQ), and performance of pCAN in the analysis of various canola samples, etc. The LODs are 15 copies for RF2, MS1, and RT73 assays using pCAN as the calibrator and 10 genome copies for the other events. The LOQ in each event-specific real-time PCR assay is 20 copies. In quantitative real-time PCR analysis, the PCR efficiencies of all event-specific and PEP assays are between 91% and 97%, and the squared regression coefficients (R) are all higher than 0.99. The quantification bias values varied from 0.47% to 20.68% with relative standard deviation (RSD) from 1.06% to 24.61% in the quantification of simulated samples. Furthermore, 10 practical canola samples sampled from imported shipments in the port of Shanghai, China, were analyzed employing pCAN as the calibrator, and the results were comparable with those assays using commercial certified materials as the calibrator. Concluding from these results, we believe that this newly developed pCAN plasmid is one good candidate for being a plasmid DNA reference material in the detection and quantification of the eight GM canola events in routine analysis.

Guo H. et al. (Bioscience reports (2018) 38, BSR20180177) published a meta-analysis concerning the association between 5 nucleotide polymorphisms (SNPs) in the high-affinity IgE receptor beta chain (FcεRIβ) gene, namely E237G, -109 C/T, RsaI_in2, RsaI_ex7, and I181L, and risk of asthma and allergic rhinitis based on available 29 case-control studies. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of association of SNPs in FcεRIβ gene with allergic diseases risk. They found that FcεRIβ E237G (237G versus 237E: OR=1.28, 95% CI=1.06-1.53) and -109 C/T (TT vs. CT+CC: OR=1.58, 95% CI=1.26-1.98) were risk factors for allergic diseases. Guo H. et al.’s findings are interesting, but we found that several issues should be clarified after careful reading the paper. Here we intended to comment on these data clarifications.