scholarly journals Impact of CRISPR interference on strain development in biotechnology

2020 ◽  
Vol 67 (1) ◽  
pp. 7-21 ◽  
Author(s):  
Kerstin Schultenkämper ◽  
Luciana F. Brito ◽  
Volker F. Wendisch
Keyword(s):  
Strain Development ◽  
Crispr Interference

Local Strain Development and Property Variability in B2 Intermetallics

2005 ◽  
Author(s):  
Tresa M. Pollock ◽  
Marc de Graef
Keyword(s):  
Local Strain ◽  
Strain Development

scholarly journals Experimental investigation on composite beams under combined negative bending and torsional moments

2020 ◽  
pp. 136943322098166
Author(s):  
Weiwei Lin
Keyword(s):  
Ultimate Load ◽  
Mechanical Performance ◽  
Composite Beams ◽  
Strain Development ◽  
Shear Connectors ◽  
Load Carrying ◽  
Interface Slip ◽  
Negative Bending ◽  
Support Conditions ◽  
Main Girder

In this study, straight composite steel-concrete beams were tested to investigate their mechanical performance under combined negative bending and torsional moments. Two specimens were used in this study, and different ratios between the applied negative bending and torsional moments were induced. Load and deflection relationships, strain development on the steel main girder and shear connectors (stud), and the slip development on the steel-concrete interface were recorded in the test and reported in this paper. The results indicate that increase of torsional moment will result in the significant decrease of the load-carrying capacities (e.g. yield load and ultimate load) of the specimens. It was also found that the normal strains of stud shear connectors in such beams are very large and non-negligible compared to their shear strains. In addition, the maximum interface slip was found occurring at around the 1/4 span, and the support conditions and serious crack of the concrete were considered to be the main causes. The research results obtained in this study can provide references for the design and analysis of steel-concrete composite beams subjected to the combined negative bending and torsional moments.

scholarly journals A multiplex CRISPR interference tool for virulence gene interrogation in Legionella pneumophila

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicole A. Ellis ◽  
Byoungkwan Kim ◽  
Jessica Tung ◽  
Matthias P. Machner
Keyword(s):  
Legionella Pneumophila ◽  
Bacterial Species ◽  
Virulence Gene ◽  
Polymerase Activity ◽  
Growth Defect ◽  
Great Promise ◽  
Macrophage Infection ◽  
Crispr Interference ◽  
Crispr Array ◽  
Virulence Protein

AbstractCatalytically inactive dCas9 imposes transcriptional gene repression by sterically precluding RNA polymerase activity at a given gene to which it was directed by CRISPR (cr)RNAs. This gene silencing technology, known as CRISPR interference (CRISPRi), has been employed in various bacterial species to interrogate genes, mostly individually or in pairs. Here, we developed a multiplex CRISPRi platform in the pathogen Legionella pneumophila capable of silencing up to ten genes simultaneously. Constraints on precursor-crRNA expression were overcome by combining a strong promoter with a boxA element upstream of a CRISPR array. Using crRNAs directed against virulence protein-encoding genes, we demonstrated that CRISPRi is fully functional not only during growth in axenic media, but also during macrophage infection, and that gene depletion by CRISPRi recapitulated the growth defect of deletion strains. By altering the position of crRNA-encoding spacers within the CRISPR array, our platform achieved the gradual depletion of targets that was mirrored by the severity in phenotypes. Multiplex CRISPRi thus holds great promise for probing large sets of genes in bulk in order to decipher virulence strategies of L. pneumophila and other bacterial pathogens.

scholarly journals Engineering of Streptoalloteichus tenebrarius 2444 for Sustainable Production of Tobramycin

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4343
Author(s):  
Lena Mitousis ◽  
Hannes Maier ◽  
Luka Martinovic ◽  
Andreas Kulik ◽  
Sigrid Stockert ◽  
...  
Keyword(s):  
Aminoglycoside Antibiotic ◽  
Biosynthetic Gene Cluster ◽  
Genetically Engineered ◽  
Sustainable Production ◽  
Biosynthetic Gene ◽  
Strain Development ◽  
Antibiotic Agent ◽  
Phenotypic Stability ◽  
High Concentrations ◽  
Hydrolysis Of

Tobramycin is a broad-spectrum aminoglycoside antibiotic agent. The compound is obtained from the base-catalyzed hydrolysis of carbamoyltobramycin (CTB), which is naturally produced by the actinomycete Streptoalloteichus tenebrarius. However, the strain uses the same precursors to synthesize several structurally related aminoglycosides. Consequently, the production yields of tobramycin are low, and the compound’s purification is very challenging, costly, and time-consuming. In this study, the production of the main undesired product, apramycin, in the industrial isolate Streptoalloteichus tenebrarius 2444 was decreased by applying the fermentation media M10 and M11, which contained high concentrations of starch and dextrin. Furthermore, the strain was genetically engineered by the inactivation of the aprK gene (∆aprK), resulting in the abolishment of apramycin biosynthesis. In the next step of strain development, an additional copy of the tobramycin biosynthetic gene cluster (BGC) was introduced into the ∆aprK mutant. Fermentation by the engineered strain (∆aprK_1-17L) in M11 medium resulted in a 3- to 4-fold higher production than fermentation by the precursor strain (∆aprK). The phenotypic stability of the mutant without selection pressure was validated. The use of the engineered S. tenebrarius 2444 facilitates a step-saving, efficient, and, thus, more sustainable production of the valuable compound tobramycin on an industrial scale.

Strain development of Streptomyces sp. for tacrolimus production using sequential adaptation

2009 ◽  
Vol 36 (12) ◽  
pp. 1467-1471 ◽  
Author(s):  
Sangwon Jung ◽  
Sunghyun Moon ◽  
Kyungsun Lee ◽  
Youn-Je Park ◽  
Sewang Yoon ◽  
...  
Keyword(s):  
Strain Development ◽  
Streptomyces Sp ◽  
Sequential Adaptation

Growth of SrTiO3/(Sr1 - x,Lax)TiO3 Superlattices and Lattice Strain Development

2006 ◽  
Vol 336 (1) ◽  
pp. 255-261 ◽  
Author(s):  
Juho Kim ◽  
Leejun Kim ◽  
Dongguen Jung ◽  
Jaichan Lee
Keyword(s):  
Lattice Strain ◽  
Strain Development

CRISPR interference and its applications

2021 ◽  
Author(s):  
Seyedkhashayar Ghavami ◽  
Amir Pandi
Keyword(s):  
Crispr Interference

Topography and lattice strain development on patterned Si surfaces

Micron ◽  
1999 ◽  
Vol 30 (1) ◽  
pp. 3-12 ◽  
Author(s):  
J.M. Blakely ◽  
C.C. Umbach
Keyword(s):  
Lattice Strain ◽  
Strain Development
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