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Scanning tunneling microscopy (STM) has been used to look at one-dimensional electronic properties of single-walled carbon nanotubes. Recent developments in this area are reviewed. Implications of studies for understanding fundamental one-dimensional physics and future nanotube device applications are discussed.

Campylobacter jejuni is the most common zoonotic bacterium associated with human diarrhea, and chickens are considered to be one of the most important sources for human infection, with no effective prophylactic treatment available. We describe here a prophylactic strategy using chitosan-DNA intranasal immunization to induce specific immune responses. The chitosan used for intranasal administration is a natural mucus absorption enhancer, which results in transgenic DNA expression in chicken nasopharynx. Chickens immunized with chitosan-DNA nanoparticles, which carried a gene for the major structural protein FlaA, produced significantly increased levels of serum anti-Campylobacter jejuni IgG and intestinal mucosal antibody (IgA), compared to those treated with chitosan-DNA (pCAGGS). Chitosan-pCAGGS-flaA intranasal immunization induced reductions of bacterial expellation by 2-3 log10 and 2 log10 in large intestine and cecum of chickens, respectively, when administered with the isolated C. jejuni strain. This study demonstrated that intranasal delivery of chitosan-DNA vaccine successfully induced effective immune response and might be a promising vaccine candidate against C. jejuni infection., 1. Introduction Gram-negative bacterium Campylobacter is responsible for an estimated 400 million human cases of enterocolitis worldwide each year, making it the leading cause of bacterial foodborne disease and a [...]

Research points out that the electronic properties of defect-free single-walled nanotubes depend both on radius and chirality as well as their curvature and local environment. One-dimensional single-walled nanotubes are employed to study interactions between magnetic clusters and one-dimensional electron hosts.

The unique structural and electronic properties of single-walled carbon nanotubes (SWNTs) are discussed. Defect-free SWNTs show semiconducting and metallic behaviour that depends on helicity and diameter.

The rapid dissemination of plasmid-mediated tet (X) genes in Acinetobacter species has compromised the clinical effectiveness of tigecycline, one of the last-resort antibiotics. However, the classification strategy and homology group of tet (X)-positive Acinetobacter spp. plasmids remain largely unknown. In this study, we classified them by genome-based replicon typing, followed by analyses of structural characteristics, transferability and in vivo effect. A total of 34 plasmids distributed in at least nine Acinetobacter species were collected, including three tet (X3)-positive plasmids and one tet (X6)-positive plasmid from our genome sequencing results. Among them, there were 28 plasmids carrying Rep&#95;3 superfamily replicase genes and classified into six homology groups, consisting of GR31 (82.1%), GR26 (3.6%), GR41 (3.6%), GR59 (3.6%), and novel groups GR60 (3.6%) and GR61 (3.6%). Our tet (X3)-positive plasmids pYH16040-1, pYH16056-1, and pYH12068-1 belonged to the dominant GR31 group, whereas the tet (X6)-positive plasmid pYH12068-2 was unclassified. Structurally, all tet (X)-positive GR31 plasmids shared similar plasmid replication ( repB ), stability ( parA and parB ) and accessory modules [ tet (X) and sul2 ], and 97.6% of plasmid-mediated tet (X) genes in Acinetobacter species were adjacent to IS CR2 . Conjugation and susceptibility testing revealed pYH16040-1, pYH16056-1, and pYH12068-2, carrying plasmid transfer modules, were able to mediate the mobilization of multiple antibiotic resistance. Under the treatment of tigecycline, the mortality rate of Galleria mellonella infected by pYH16040-1-mediated tet (X3)-positive Acinetobacter spp. isolate significantly increased when compared with its plasmid-cured strain ( p < 0.0001). The spread of such plasmids is of great clinical concern, more effects are needed and will facilitate the future analysis of tet (X)-positive Acinetobacter spp. plasmids., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Chen, Huang, Cui, He, Sun, Liu and Huang.)

Aim: Expression, purification of Campylobacter jejuni CjaA protein and development of monoclonal antibodies (mAbs) against this protein., Methods: The C. jejuni cjaA gene was amplified and inserted into the expression plasmids, pGEX-6p-1 and pET30a (+). The purified rGST-CjaA protein was used as an immunogen in 8-week-old BALB/c mice, and injected subcutaneously. The purified rHis-CjaA protein used as a detecting antigen for screening mAbs against CjaA was prepared. The specificity of mAbs was characterized by Dot-ELISA and Western blot assays., Results: The recombinant expression plasmids, pGEX-6p-1-cjaA and pET30a(+)-cjaA were obtained. The sizes of the recombinant proteins, rGST-CjaA and rHis-CjaA, were consistent with their predicted size. Specific reaction was found between CjaA positive serum and expressed protein by Western blot assay, confirming its identification as a Campylobacter jejuni immunogen. Three hybridoma cell lines, designated 2B6, 3C2 and 4F11, secreting mAbs against CjaA were obtained. Their immunoglobulin subclasses were all IgG1. The ELISA titers of the ascites fluid were 1:1×10(5);, 1:2×10(5); and 1:4×10(5);, respectively. Western blot analysis confirmed that the three mAbs reacted with the rHis-CjaA fusion protein but not the His tag. The Dot-ELISA results demonstrated that the three mAbs only with CjaA and not the tags for the expression vectors., Conclusion: The successful preparation of three mAbs specific for the CjaA protein lays the foundation for further study regarding the biological characteristics of CjaA and the pathogenesis of C. jejuni.

Aim: To express recombinant bovine IL-4 (rBoIL-4) in Escherichia coli and prepare monoclonal antibody (mAb) against rBoIL-4., Methods: The IL-4 gene without coding signal peptides was amplified from pSP73-BoIL-4 by PCR, then inserted into prokaryotic expression vector pGEX-6p-1 and pET-30a(+). The recombinant plasmids pGEX-6p-1-BoIL-4 and pET-BoIL-4 were transformed into DH5α for sequencing. After sequencing confirmation, the two recombinant plasmids were transformed into expression bacteria BL21 and BL21(DE3) respectively. BALB/c mice were immunized with the purified protein rHis-BoIL-4. With the purified rGST-BoIL-4 as detecting antigen, mAb-produced hybridoma cells against BoIL-4 were screened by indirect ELISA. The specificity of the mAbs was characterized by indirect ELlSA, Dot-ELlSA and Western blot., Results: The recombinant bacteria BL21(pGEX-6p-1-BoIL-4) and BL21(DE3)(pET-BoIL-4) were developed. After induced by IPTG, SDS-PAGE analysis showed that the expression products of rGST-BoIL-4 and rHis-BoIL-4 had a molecular weight of 39 kD and 19 kD respectively, and expressed in inclusion body form. Seven hybridoma cell lines secreting mAbs against BoIL-4, named 2B8, 4A10, 5D6, 5D8, 7G10, 8B7 and 10F8 were obtained. The immunoglobulin subclasses were IgG1. The ascitic titers of these mAbs were 5 000, 16 0000, 10 000, 640 000, 5 000, 40 000 and 40 000, respectively. In Dot-ELISA, all mAbs could only react to the immunogen and the detecting antigen. Western-blot analysis confirmed that mAbs could only react to the corresponding recombinant proteins. The mAbs also reacted to the standard recombinant boIL-4 with biological activity., Conclusion: Seven mAbs specific to rBoIL-4 protein are obtained, which may have important application value in further study on diagnosis and pathogenesis of cattle diseases.

Aim: To determine the role of ESAT-6 chimeric flagellin in TB immunology., Methods: The coding sequences of flagellin of Salmonella typhimurium and ESAT-6 of Mycobacterium tuberculosis were cloned by PCR and identified by sequencing, respectively. Chimeric flagellin gene fliC/esat was constructed by overlap PCR technique. The ESAT-6 coding fragment was inserted to the hypervariable region of Salmonella flagellin gene fliCi. And then prokaryotic exprssion plasmids of pET-fliC/esat, pET-fliC and pBCX-esat were constructed and transformed into E.coli BL21(DE3), followed by induction of IPTG. The expressed proteins fliC/esat and ESAT-6 were identified by Western-blot assay using specific monoclonal antibody (mAb) HYB076-08. Bone marrow dendritic cells (BMDCs) were in vitro stimulated by fliC/esat and ESAT-6 proteins, and analyzed for the expression levels of CD40, CD80, CD86 and CD54 molecules. The secreted IL-12p70 was determined by ELISA. Moreover, C57BL/6 mice were immunized intravenously with fliC/esat or ESAT-6 protein. The specific IFN-γ-secreting cells and IL-4-secreting cells from the immunized mice were detected by ELISPOT assay using an ESAT-6 peptide as a stimulus., Results: The results showed that the proteins of fliC/esat and ESAT-6 were expressed solubly, with the sizes of 64 kD and 39 kD respectively. Western blot analysis showed that both proteins reacted with the specific mAb against ESAT-6. BMDCs maturation was triggered by the chimeric flagellin fliC/esat. In contrast, ESAT-6 protein alone didn't activate BMDCs. IL-12p70 was also detected in the supernatants of BMDCs. The results showed that the chimeric flagellin fliC/esat induced significantly higher level of the secreted IL-12p70 than that of ESAT-6 protein. Furthermore, the chimeric flagellin fliC/esat significantly enhanced the Th1-biased immune responses against ESAT-6 in the immunized C57BL/6 mice., Conclusion: The chimeric flagellin we generated exerts Th1 type adjuvant activity for ESAT-6 protein.

Aim: To prepare the monoclonal antibodies (mAbs) against listeriolysin O (LLO), which is the major virulence factor of Listeria monocytogenes., Methods: The BALB/c mice were immunized with the SDS-PAGE product of BL21(pGEX-6p-1-hly). The purified LLO-GST protein was used as antigen for detection. mAbs against LLO were prepared by using the lymphocyte hybridoma technique. The specificity of mAbs was characterized by Dot-ELISA and Western blot., Results: Three hybridoma cell lines named 3B6, 4D1 and 5D10 secreting mAbs against LLO were obtained. The immunoglobulin subclasses of the mAbs were IgG1. The ELISA titer of the ascitic fluids of 3B6, 4D1 and 5D10 was 1:200,000, 1:200,000 and 1:100,000, respectively. Western blot analysis confirmed the three mAbs reacted on fusion protein LLO-GST but didn't react on protein GST. Dot-ELISA proved the three mAbs only react on the bacteria expressing LLO., Conclusion: The successful preparation of three mAbs specific to protein LLO lays a foundation for further study of the biological characteristics of LLO and the pathogenesis of Listeria monocytogenes.