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Selective markers employed in classical mutagenesis methods using natural genetic transformation can affect gene expression, risk phenotypic effects, and accumulate as unwanted genes during successive mutagenesis cycles. In this chapter, we present a protocol for markerless genome editing in Streptococcus mutans and Streptococcus pneumoniae achieved with an efficient method for natural transformation. High yields of transformants are obtained by combining the unimodal state of competence developed after treatment of S. mutans with sigX-inducing peptide pheromone (XIP) in a chemically defined medium (CDM) or of S. pneumoniae with the competence-stimulating peptide (CSP) together with use of a donor amplicon carrying extensive flanking homology. This combination ensures efficient and precise integration of a new allele by the recombination machinery present in competent cells.
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http://dx.doi.org/10.1007/978-1-0716-2780-8_13 | DOI Listing |
G3 (Bethesda)
August 2025
Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, USA.
In vivo site-directed mutagenesis is a powerful genetic tool for testing the effects of specific alleles in their normal genomic context. While the budding yeast Saccharomyces cerevisiae possesses classical tools for site-directed mutagenesis, more efficient recent CRISPR-based approaches use Cas 'cutting' combined with homologous recombination of a 'repair' template that introduces the desired edit. However, current approaches are limited for fully prototrophic yeast strains, and rely on relatively low efficiency cloning of short gRNAs.
View Article and Find Full Text PDFJ Microbiol Biotechnol
July 2025
Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P.R. China.
Site-specific recombination enables precise and modular genome engineering in microbial systems. In , Cre is the most commonly used site-specific recombinase (SSR) and has been widely applied in genome engineering. Developing SSRs with comparable performance to Cre that can also function orthogonally would significantly expand the genome engineering toolkit.
View Article and Find Full Text PDFAppl Microbiol Biotechnol
July 2025
Chair of Microbiology, Technical University of Munich, TUM School of Life Sciences, Emil-Ramann-Str. 4, Freising, 85354, Germany.
This study demonstrates the impact of a Structure Maintenance of Chromosome (SMC)-like Wadjet system on the horizontal gene transfer of plasmids by conjugation to a recipient that naturally containing such a system for the first time. A Clostridium cellulovorans mutant with dramatically improved efficiency to receive plasmid DNA by conjugation was isolated and sequenced. Three spontaneous chromosomal deletions included a type II restriction-modification system, a putative CRISPR system, and a cluster of ORFs named jetABCD encoding a putative Wadjet system.
View Article and Find Full Text PDFbioRxiv
June 2025
Program in Microbiology and Immunology, University of Pittsburgh School of Medicine, Pittsburgh PA, USA.
(group B ; GBS) is a leading cause of neonatal sepsis and meningitis. Despite advances in molecular microbiology, GBS genome engineering remains laborious due to inefficient mutagenesis protocols. Here, we report a versatile and rapid Cas12a-based toolkit for GBS genetic manipulation.
View Article and Find Full Text PDFSci Adv
June 2025
Systems Neuroscience Section, Center for the Evolutionary Origins of Human Behavior, Kyoto University, Inuyama, Japan.
Given their high sociality and close evolutionary distance to humans, monkeys are an essential animal model for unraveling the biological mechanisms underlying human social behavior and elucidating the pathogenesis of diseases exhibiting abnormal social behavior. However, behavioral analysis of naturally behaving monkeys requires manual counting of various behaviors, which has been a bottleneck due to problems in throughput and objectivity. Here, we developed a three-dimensional markerless motion capture system that used multi-view data for robust tracking of individual monkeys and accurate reconstruction of the three-dimensional poses of multiple monkeys living in groups.
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