scholarly journals Linear plasmids and their replication

2013 ◽  
Vol 2 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Sunjukta Ahsan ◽  
Md Shahidul Kabir
Keyword(s):  
Causative Agent ◽  
Salmonella Enterica ◽  
The Other ◽  
Linear Plasmid ◽  
Covalent Attachment ◽  
Common Belief ◽  
Replication Machinery ◽  
Linear Plasmids ◽  
Salmonella Enterica Serovar Typhi ◽  
First Time

It is still a common belief that plasmids are circular. However, linear plasmids have been reported to exist more than a decade ago. Two types of linear plasmids are known. One type contains covalently closed ends and are commonly found in Borrelia, the causative agent of tick fever. The other type is characterized by the covalent attachment of proteins at the 5' ends and exists in a number of bacterial genera including Streptomyces, Rhodococcus, Mycobacterium and Planobispora. Recently, a linear plasmid in Salmonella enterica serovar Typhi of the Enterobacteriaceae family have been reported for the first time. This paper reviews various postulated mechanisms of replication of linear plasmids and focuses on the components of the replication machinery of linear plasmids studied to date. DOI: http://dx.doi.org/10.3329/sjm.v2i1.15200 Stamford Journal of Microbiology, Vol.2(1) 2012: 1-5

scholarly journals Salmonella enterica Serovar Typhi Possesses a Unique Repertoire of Fimbrial Gene Sequences

2001 ◽  
Vol 69 (5) ◽  
pp. 2894-2901 ◽  
Author(s):  
Stacy M. Townsend ◽  
Naomi E. Kramer ◽  
Robert Edwards ◽  
Stephen Baker ◽  
Nancy Hamlin ◽  
...  
Keyword(s):  
Host Range ◽  
Salmonella Enterica ◽  
Host Adaptation ◽  
Unique Combination ◽  
Gene Sequences ◽  
Simple Correlation ◽  
Salmonella Enterica Serovar Typhi ◽  
Type Iv ◽  
Reference Collection ◽  
First Time

ABSTRACT Salmonella enterica serotype Typhi differs from nontyphoidal Salmonella serotypes by its strict host adaptation to humans and higher primates. Since fimbriae have been implicated in host adaptation, we investigated whether the serotype Typhi genome contains fimbrial operons which are unique to this pathogen or restricted to typhoidal Salmonella serotypes. This study established for the first time the total number of fimbrial operons present in an individual Salmonella serotype. The serotype Typhi CT18 genome, which has been sequenced by the Typhi Sequencing Group at the Sanger Centre, contained a type IV fimbrial operon, an orthologue of the agf operon, and 12 putative fimbrial operons of the chaperone-usher assembly class. In addition tosef, fim, saf, and tcf, which had been described previously in serotype Typhi, we identified eight new putative chaperone-usher-dependent fimbrial operons, which were termedbcf, sta, stb, ste, std, stc, stg, and sth. Hybridization analysis performed with 16 strains ofSalmonella reference collection C and 22 strains ofSalmonella reference collection B showed that all eight putative fimbrial operons of serotype Typhi were also present in a number of nontyphoidal Salmonella serotypes. Thus, a simple correlation between host range and the presence of a single fimbrial operon seems at present unlikely. However, the serotype Typhi genome differed from that of all other Salmonella serotypes investigated in that it contained a unique combination of putative fimbrial operons.

scholarly journals Expression of fljB: z66 on a linear plasmid of Salmonella enterica serovar typhi is dependent on FliA and FlhDC and regulated by OmpR

2010 ◽  
Vol 41 (3) ◽  
pp. 729-740 ◽  
Author(s):  
Shungao Xu ◽  
Xin Zou ◽  
Xiumei Sheng ◽  
Haifang Zhang ◽  
Lingxiang Mao ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Linear Plasmid ◽  
Salmonella Enterica Serovar Typhi

scholarly journals Fis Is Essential for the Stability of Linear Plasmid pBSSB1 and Affects the Motility of Salmonella enterica Serovar Typhi

PLoS ONE ◽  
2012 ◽  
Vol 7 (7) ◽  
pp. e37462 ◽  
Author(s):  
Haifang Zhang ◽  
Bin Ni ◽  
Xin Zhao ◽  
Isaac Dadzie ◽  
Hong Du ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Linear Plasmid ◽  
Salmonella Enterica Serovar Typhi ◽  
The Stability

Detection of a large linear plasmid inBorrelia spielmaniiisolate

2011 ◽  
Vol 57 (4) ◽  
pp. 343-346
Author(s):  
Daniela Handžáková Lenčáková ◽  
Ulrike Schulte-Spechtel ◽  
Volker Fingerle ◽  
Branislav Pet’ko ◽  
Bettina Wilske
Keyword(s):  
Lyme Disease ◽  
Gel Electrophoresis ◽  
Previous History ◽  
Pulsed Field Gel Electrophoresis ◽  
Linear Plasmid ◽  
Borrelia Burgdorferi Sensu Lato ◽  
Large Plasmid ◽  
Linear Plasmids ◽  
History Of ◽  
First Time

Borrelia spielmanii belongs to human pathogenic species within the Borrelia burgdorferi sensu lato complex in Europe, which is a causative agent of Lyme disease. So far, the human disease caused by B. spielmanii has been associated with skin manifestations. The aim of the study was to analyze 4 human B. spielmanii isolates by pulsed-field gel electrophoresis and to localize genes of 3 important Borrelia proteins: OspA, DbpA, and VlsE. The analysis revealed variation within linear plasmid profiles among the strains; isolate PSigII contained a large plasmid of 100 kb compared with a 50 kb plasmid present in the 3 other B. spielmanii isolates, all carried the genes ospA and dbpA. Differences in the size of linear plasmids among the Borrelia strains may be a result of host–pathogen interactions, as the PSigII strain was the only strain of the 4 tested strains to be isolated from a patient with a previous history of Lyme disease, whereas 3 other patients were diagnosed with this disease for the first time.

scholarly journals Inconsistency of Simulation and Practice in Delay-based Strong PUFs

2021 ◽  
pp. 520-551
Author(s):  
Anita Aghaie ◽  
Amir Moradi
Keyword(s):  
Critical Role ◽  
The Other ◽  
Divide And Conquer ◽  
Learning Problems ◽  
Common Belief ◽  
Physical Unclonable Functions ◽  
Open Research ◽  
Simulation Domain ◽  
First Time

The developments in the areas of strong Physical Unclonable Functions (PUFs) predicate an ongoing struggle between designers and attackers. Such a combat motivated the atmosphere of open research, hence enhancing PUF designs in the presence of Machine Learning (ML) attacks. As an example of this controversy, at CHES 2019, a novel delay-based PUF (iPUF) has been introduced and claimed to be resistant against various ML and reliability attacks. At CHES 2020, a new divide-and-conquer modeling attack (splitting iPUF) has been presented showing the vulnerability of even large iPUF variants.Such attacks and analyses are naturally examined purely in the simulation domain, where some metrics like uniformity are assumed to be ideal. This assumption is motivated by a common belief that implementation defects (such as bias) may ease the attacks. In this paper, we highlight the critical role of uniformity in the success of ML attacks, and for the first time present a case where the bias originating from implementation defects hardens certain learning problems in complex PUF architectures. We present the result of our investigations conducted on a cluster of 100 Xilinx Artix 7 FPGAs, showing the incapability of the splitting iPUF attack to model even small iPUF instances when facing a slight non-uniformity. In fact, our findings imply that non-ideal conditions due to implementation defects should also be considered when developing an attack vector on complex PUF architectures like iPUF. On the other hand, we observe a relatively low uniqueness even when following the suggestions made by the iPUF’s original authors with respect to the FPGA implementations, which indeed questions the promised physical unclonability.

scholarly journals Identification of a fljA gene on a linear plasmid as the repressor gene of fliC in Salmonella enterica serovar Typhi

2008 ◽  
Vol 53 (4) ◽  
pp. 191-197 ◽  
Author(s):  
Xin Zou ◽  
Xinxiang Huang ◽  
Shungao Xu ◽  
Liping Zhou ◽  
Xiumei Sheng ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Linear Plasmid ◽  
Repressor Gene ◽  
Salmonella Enterica Serovar Typhi

scholarly journals B Cells Control Mucosal-Associated Invariant T Cell Responses to Salmonella enterica Serovar Typhi Infection Through the CD85j HLA-G Receptor

2021 ◽  
Vol 12 ◽  
Author(s):  
Rosângela Salerno-Gonçalves ◽  
Tasmia Rezwan ◽  
David Luo ◽  
Hervé Tettelin ◽  
Marcelo B. Sztein
Keyword(s):  
B Cells ◽  
Salmonella Enterica ◽  
Kinetic Studies ◽  
Salmonella Enterica Serovar Typhi ◽  
Mait Cells ◽  
Cell Responses ◽  
Ifn Γ ◽  
And Function ◽  
First Time ◽  
Mait Cell

Mucosal-associated invariant T (MAIT) cells are an innate-like population of T cells that display a TCR Vα7.2+ CD161+ phenotype and are restricted by the nonclassical MHC-related molecule 1 (MR1). Although B cells control MAIT cell development and function, little is known about the mechanisms underlying their interaction(s). Here, we report, for the first time, that during Salmonella enterica serovar Typhi (S. Typhi) infection, HLA-G expression on B cells downregulates IFN-γ production by MAIT cells. In contrast, blocking HLA-G expression on S. Typhi-infected B cells increases IFN-γ production by MAIT cells. After interacting with MAIT cells, kinetic studies show that B cells upregulate HLA-G expression and downregulate the inhibitory HLA-G receptor CD85j on MAIT cells resulting in their loss. These results provide a new role for HLA-G as a negative feedback loop by which B cells control MAIT cell responses to antigens.

scholarly journals Multiplex PCR for Identification of Salmonella enterica serovars Typhi and Paratyphi A by Selective Amplification of tyv, prt, viaB, fliC-d and fliC-a Genes

2014 ◽  
Vol 8 (2) ◽  
pp. 60-65
Author(s):  
Ashna J. Faik ◽  
Ali Hussain Al-wardy ◽  
Raghad Abdul Elah Mohammad
Keyword(s):  
Multiplex Pcr ◽  
Causative Agent ◽  
Salmonella Enterica ◽  
Rapid Identification ◽  
Clinical Isolates ◽  
Flagellin Gene ◽  
Salmonella Enterica Serovar Typhi ◽  
D Antigen ◽  
Paratyphoid Fever ◽  
Vi Antigen

Salmonellosis is responsible for large number of infections in both human and animals. Salmonella enterica serovar Typhi is a causative agent of typhoid fever and Salmonella enterica serovar Paratyphi A is a causative agent of paratyphoid fever. Conventional methods of isolation of Salmonella strains take 4-6 days to complete and are therefore laborious and require substiantial manpower. Therefore development of a PCR assay that can target multiple genes for rapid detection of S. Typhi and S.Paratyphi A. Methods: Synthetic primers for O, H, and Vi antigen genes, tyv , prt , fliC-d, fliC-a, and viaB, were used for the rapid identification of S. Typhi and Paratyphi A with Multiplex PCR. Results: All the clinical isolates examined were accurately identified by this PCR technique, that differentiated S. Typhi and Paratyphi A, based on size and number of amplified fragments. S. enterica serovar Typhi, yielded four bands of tyv(tyvelose epimerase gene, 615bp),prt (paratose gene, 258bp),flic-d(phage-1 flagellin gene for d- antigen 750bp) and viaB ( vi antigen gene, 439bp); S.enterica serovar Paratyphi A yielded only two bands prt (paratose gene, 258bp) and flic-a (phage-1 flagellin gene for a- antigen 329bp). Conclusion: These data indicate that multiplex PCR is a potentially valuable tool for rapid diagnosis of Salmonella enterica serovar Typhi and Paratyphi A from clinical isolates.

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