scholarly journals Analysis of Two Complementary Single-Gene Deletion Mutant Libraries of Salmonella Typhimurium in Intraperitoneal Infection of BALB/c Mice

2016 ◽  
Vol 6 ◽  
Author(s):  
Cecilia A. Silva-Valenzuela ◽  
Roberto C. Molina-Quiroz ◽  
Prerak Desai ◽  
Camila Valenzuela ◽  
Steffen Porwollik ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Deletion Mutant ◽  
Gene Deletion ◽  
Single Gene ◽  
Intraperitoneal Infection ◽  
Gene Deletion Mutant ◽  
Single Gene Deletion

scholarly journals 6S-1 RNA Contributes to Sporulation and Parasporal Crystal Formation in Bacillus thuringiensis

2020 ◽  
Vol 11 ◽  
Author(s):  
Zhou Li ◽  
Li Zhu ◽  
Zhaoqing Yu ◽  
Lu Liu ◽  
Shan-Ho Chou ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Deletion Mutant ◽  
Gene Deletion ◽  
Gene Knockout ◽  
Single Gene ◽  
Crystal Formation ◽  
Bacterial Cells ◽  
Parasporal Crystal ◽  
6S Rna ◽  
Gene Deletion Mutant

6S RNA is a kind of high-abundance non-coding RNA that globally regulates bacterial transcription by interacting with RNA polymerase holoenzyme. Through bioinformatics analysis, we found that there are two tandem 6S RNA-encoding genes in the genomes of Bacillus cereus group bacteria. Using Bacillus thuringiensis BMB171 as the starting strain, we have explored the physiological functions of 6S RNAs, and found that the genes ssrSA and ssrSB encoding 6S-1 and 6S-2 RNAs were located in the same operon and are co-transcribed as a precursor that might be processed by specific ribonucleases to form mature 6S-1 and 6S-2 RNAs. We also constructed two single-gene deletion mutant strains ΔssrSA and ΔssrSB and a double-gene deletion mutant strain ΔssrSAB by means of the markerless gene knockout method. Our data show that deletion of 6S-1 RNA inhibited the growth of B. thuringiensis in the stationary phase, leading to lysis of some bacterial cells. Furthermore, deletion of 6S-1 RNA also significantly reduced the spore number and parasporal crystal content. Our work reveals that B. thuringiensis 6S RNA played an important regulatory role in ensuring the sporulation and parasporal crystal formation.

scholarly journals Defined Single-Gene and Multi-Gene Deletion Mutant Collections in Salmonella enterica sv Typhimurium

PLoS ONE ◽  
2014 ◽  
Vol 9 (7) ◽  
pp. e99820 ◽  
Author(s):  
Steffen Porwollik ◽  
Carlos A. Santiviago ◽  
Pui Cheng ◽  
Fred Long ◽  
Prerak Desai ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Deletion Mutant ◽  
Gene Deletion ◽  
Single Gene ◽  
Gene Deletion Mutant

scholarly journals Mutability of demographic noise in microbial range expansions

2021 ◽  
Author(s):  
QinQin Yu ◽  
Matti Gralka ◽  
Marie-Cécilia Duvernoy ◽  
Megan Sousa ◽  
Arbel Harpak ◽  
...  
Keyword(s):  
Gene Deletion ◽  
Genetic Manipulation ◽  
Single Gene ◽  
Population Level ◽  
Growth Conditions ◽  
Establishment Probability ◽  
In The Wild ◽  
Order Of Magnitude ◽  
Demographic Noise ◽  
Single Gene Deletion

AbstractDemographic noise, the change in the composition of a population due to random birth and death events, is an important driving force in evolution because it reduces the efficacy of natural selection. Demographic noise is typically thought to be set by the population size and the environment, but recent experiments with microbial range expansions have revealed substantial strain-level differences in demographic noise under the same growth conditions. Many genetic and phenotypic differences exist between strains; to what extent do single mutations change the strength of demographic noise? To investigate this question, we developed a high-throughput method for measuring demographic noise in colonies without the need for genetic manipulation. By applying this method to 191 randomly-selected single gene deletion strains from the E. coli Keio collection, we find that a typical single gene deletion mutation decreases demographic noise by 8% (maximal decrease: 81%). We find that the strength of demographic noise is an emergent trait at the population level that can be predicted by colony-level traits but not cell-level traits. The observed differences in demographic noise from single gene deletions can increase the establishment probability of beneficial mutations by almost an order of magnitude (compared to in the wild type). Our results show that single mutations can substantially alter adaptation through their effects on demographic noise and suggest that demographic noise can be an evolvable trait of a population.

scholarly journals Novel Swine Virulence Determinant in the Left Variable Region of the African Swine Fever Virus Genome

2002 ◽  
Vol 76 (7) ◽  
pp. 3095-3104 ◽  
Author(s):  
J. G. Neilan ◽  
L. Zsak ◽  
Z. Lu ◽  
G. F. Kutish ◽  
C. L. Afonso ◽  
...  
Keyword(s):  
Deletion Mutant ◽  
Gene Deletion ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Variable Region ◽  
Fever Virus ◽  
Marker Rescue ◽  
Virulence Determinant ◽  
Gene Deletion Mutant

ABSTRACT Previously we have shown that the African swine fever virus (ASFV) NL gene deletion mutant E70ΔNL is attenuated in pigs. Our recent observations that NL gene deletion mutants of two additional pathogenic ASFV isolates, Malawi Lil-20/1 and Pr4, remained highly virulent in swine (100% mortality) suggested that these isolates encoded an additional virulence determinant(s) that was absent from E70. To map this putative virulence determinant, in vivo marker rescue experiments were performed by inoculating swine with infection-transfection lysates containing E70 NL deletion mutant virus (E70ΔNL) and cosmid DNA clones from the Malawi NL gene deletion mutant (MalΔNL). A cosmid clone representing the left-hand 38-kb region (map units 0.05 to 0.26) of the MalΔNL genome was capable of restoring full virulence to E70ΔNL. Southern blot analysis of recovered virulent viruses confirmed that they were recombinant E70ΔNL genomes containing a 23- to 28-kb DNA fragment of the Malawi genome. These recombinants exhibited an unaltered MalΔNL disease and virulence phenotype when inoculated into swine. Additional in vivo marker rescue experiments identified a 20-kb fragment, encoding members of multigene families (MGF) 360 and 530, as being capable of fully restoring virulence to E70ΔNL. Comparative nucleotide sequence analysis of the left variable region of the E70ΔNL and Malawi Lil-20/1 genomes identified an 8-kb deletion in the E70ΔNL isolate which resulted in the deletion and/or truncation of three MGF 360 genes and four MGF 530 genes. A recombinant MalΔNL deletion mutant lacking three members of each MGF gene family was constructed and evaluated for virulence in swine. The mutant virus replicated normally in macrophage cell culture but was avirulent in swine. Together, these results indicate that a region within the left variable region of the ASFV genome containing the MGF 360 and 530 genes represents a previously unrecognized virulence determinant for domestic swine.

scholarly journals The Expression Levels of Outer Membrane Proteins STM1530 and OmpD, Which Are Influenced by the CpxAR and BaeSR Two-Component Systems, Play Important Roles in the Ceftriaxone Resistance ofSalmonella entericaSerovar Typhimurium

2011 ◽  
Vol 55 (8) ◽  
pp. 3829-3837 ◽  
Author(s):  
Wensi S. Hu ◽  
Hung-Wen Chen ◽  
Rui-Yang Zhang ◽  
Chung-Yi Huang ◽  
Chi-Fan Shen
Keyword(s):  
Outer Membrane ◽  
Deletion Mutant ◽  
Gene Deletion ◽  
Mrna Levels ◽  
Protein Levels ◽  
Component Systems ◽  
Two Component ◽  
Serovar Typhimurium ◽  
Two Component Systems ◽  
Gene Deletion Mutant

ABSTRACTSignificant increases in STM3031, STM1530, and AcrD protein levels and significant decreases in OmpC and OmpD protein levels are present when the ceftriaxone-resistantSalmonella entericaserovar Typhimurium R200 strain is compared with the ceftriaxone-susceptible strain 01-4. AcrD is known to be involved in drug export, and STM3031 seems to play a key role in ceftriaxone resistance. Here, we examine the roles of STM1530, OmpC, and OmpD in ceftriaxone resistance. AnompDgene deletion mutant showed 4-fold higher ceftriaxone resistance than 01-4. AnompCgene deletion mutant showed 4-fold higher cephalothin and erythromycin resistance than 01-4, but there was no effect on ceftriaxone resistance. However, astm1530deletion mutant did show >64-fold lower ceftriaxone resistance than R200. Moreover, the STM3031 protein was significantly decreased in R200(Δstm1530) compared to R200. STM3031 expression has been shown to be influenced by the two-component system regulator genebaeR. CpxR seems to modulate BaeR. AcpxA-cpxRgene deletion mutant showed >2,048-fold lower ceftriaxone resistance than R200. The outer membrane protein profile of R200(ΔcpxAR) showed significant decreases in STM3031 and STM1530 compared to R200, while OmpD had returned to the level found in 01-4. Furthermore, thestm3031,stm1530, andompDmRNA levels were correlated with their protein expression levels in these strains, while decreases in the mRNA levels of the efflux pumpacrB,acrD, andacrFgenes were found in R200(ΔcpxAR). Findings similar to those for R200(ΔcpxAR) were found for R200(ΔbaeSR). These results, together with those for STM3031 and the fact that STM1530 is an outer membrane protein, suggest that STM1530 and OmpD are influenced by the CpxAR and BaeSR two-component systems and that this contributes toS. entericaserovar Typhimurium ceftriaxone resistance.

scholarly journals A Comprehensive Analysis of Replicative Lifespan in 4,698 Single-Gene Deletion Strains Uncovers Conserved Mechanisms of Aging

2015 ◽  
Vol 22 (5) ◽  
pp. 895-906 ◽  
Author(s):  
Mark A. McCormick ◽  
Joe R. Delaney ◽  
Mitsuhiro Tsuchiya ◽  
Scott Tsuchiyama ◽  
Anna Shemorry ◽  
...  
Keyword(s):  
Gene Deletion ◽  
Single Gene ◽  
Comprehensive Analysis ◽  
Replicative Lifespan ◽  
Single Gene Deletion

Evaluation of Low Mean Corpuscular Volume in an Apheresis Donor Population.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4136-4136
Author(s):  
Barbara J. Bryant ◽  
Julie A. Hopkins ◽  
Susan F. Leitman
Keyword(s):  
Iron Deficiency ◽  
Mean Corpuscular Volume ◽  
Gene Deletion ◽  
Single Gene ◽  
Transferrin Saturation ◽  
Hemoglobin S ◽  
Alpha Thalassemia ◽  
Donor Population ◽  
Thalassemia Trait ◽  
Single Gene Deletion

Abstract Donors of apheresis blood components are routinely evaluated with a complete blood count (CBC) at the time of each donation. In otherwise healthy donors, recurrent low mean corpuscular volume (MCV) values (< 80 fL) in the presence of an acceptable hemoglobin (≥ 12.5 gm/dL) could be due to iron deficiency or to an hemoglobinopathy, such as alpha thalassemia trait or a beta chain variant trait. Iron deficiency in repeat blood donors may warrant treatment with oral iron supplementation, whereas donors with hemoglobinopathies in the absence of iron deficiency do not need treatment. Pre-donation samples for CBC (Cell-Dyn 4000, Abbott) were obtained from all apheresis donors donating platelets, plasma, granulocytes, lymphocytes, and monocytes. MCV values <80 fL were electronically flagged via a donor database module for review by medical staff. Donors with MCV ≤ 80 fL on two or more occasions were evaluated for iron deficiency and the presence of hemoglobinopathies. CBC, ferritin, serum iron, transferrin, percent transferrin saturation, and hemoglobin electrophoresis were performed at the time of a subsequent donation. Iron deficiency was defined as values below the reference range for ferritin or transferrin saturation. Alpha thalassemia trait was presumed if the red blood cell count was elevated, no variant hemoglobins were detected by electrophoresis, and the ferritin, percent transferrin saturation, serum iron, and transferrin levels were all within normal ranges. In a one-year period, 25 of 1333 healthy apheresis donors had a low MCV on more than one occasion. Donors with low MCV were more likely to be African American (AA) (12 of 25, 48%) or Asian (2 of 25, 8%) compared with donors without a low MCV (AA 193 of 1308, 15%; Asian 37 of 1308, 3%). Iron deficiency was present in 60% (15 of 25) of the low-MCV donors: 36% (9) had isolated iron deficiency, 20% (5) had iron deficiency with probable alpha thalassemia trait, and 4% (1) had hemoglobin C trait with coexistent iron deficiency. Hemoglobinopathy without concomitant iron deficiency was found in 40% (10 of 25) of the low-MCV donors and included 24% (6) with presumed alpha thalassemia trait, 4% (1) with hemoglobin S trait and single gene deletion alpha thalassemia trait (hemoglobin S concentration 34%), 4% (1) with hemoglobin S trait and double gene deletion alpha thalassemia trait (hemoglobin S concentration 28%), 4% (1) with hemoglobin Lepore trait, and 4% (1) with hemoglobin G-Philadelphia trait with at least a single gene deletion alpha thalassemia trait (hemoglobin G-Philadelphia concentration 36%). Although the combination of MCV, hemoglobin, and red cell count available from the routine CBC were often helpful in discriminating iron deficiency from hemoglobinopathy, the frequent coexistence of both processes resulted in a need for further laboratory evaluation, both before and after iron repletion, to confirm the diagnosis. In a sample of American repeat apheresis donors, iron deficiency is present in the majority with recurrent low MCV values and hemoglobin levels ≥ 12.5 gm/dL. Concurrent hemoglobinopathy is also commonly present but may not be easily recognized in the setting of iron deficiency. The MCV is a useful screening tool to detect iron deficiency in a repeat blood donor population, however low MCV values should be further investigated in the blood donor setting to determine if iron replacement therapy is indicated.

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