Streptococci deficient in genetic transformation

1971 ◽  
Vol 17 (10) ◽  
pp. 1251-1257 ◽  
Author(s):  
R. Pakula ◽  
L. R. Spencer ◽  
P. A. Goldstein
Keyword(s):  
Drug Resistance ◽  
Genetic Transformation ◽  
Dna Uptake ◽  
Low Efficiency

Three strains of group H streptococci have been found to produce competence factors (CF's) similar to that synthesized by the highly transformable strain Challis. All these factors efficiently converted to competency for DNA uptake the spontaneously nontransformable strain Wicky. Two of the three strains could be transformed to drug resistance with an extremely low efficiency and one strain was nontransformable. When the bacteria were exposed to tritium-labeled DNA, it was found that a viable unit of the three strains contained about 10 times less radioactivity than a viable unit of Challis and Wicky in the competent state. The probability that CF may not be the only factor required for DNA uptake is discussed.

scholarly journals Overcoming the Barrier of Low Efficiency during Genetic Transformation of Streptococcus mitis

2016 ◽  
Vol 07 ◽  
Author(s):  
Gabriela Salvadori ◽  
Roger Junges ◽  
Donald A. Morrison ◽  
Fernanda C. Petersen
Keyword(s):  
Genetic Transformation ◽  
Streptococcus Mitis ◽  
Low Efficiency

Genetic transformation of Chainia and heat attenuation of its restriction system

1991 ◽  
Vol 37 (9) ◽  
pp. 713-715 ◽  
Author(s):  
Vijay M. Chauthaiwale ◽  
Pranav R. Vyas ◽  
Vasanti V. Deshpande
Keyword(s):  
Genetic Transformation ◽  
Key Words ◽  
Broad Host Range ◽  
Transformation System ◽  
Restriction System ◽  
Plasmid Replicon ◽  
Commercially Important ◽  
Low Efficiency ◽  
The Many ◽  
Restriction Modification

A PEG-mediated transformation system for Chainia (NCL 82-5-1) was develolped using a broad host range Streptomyces vector, pIJ702. Protoplasts prepared from Chainia (NCL 82-5-1) were regenerated with 5% efficiency. Transformation of the protoplasts with pIJ702 gave 10–20 transformants/μg DNA. The low efficiency of transformation is attributed to a restriction system in Chainia; this could be inhibited by treating the protoplasts at 42 °C for 10 min just before transformation. The yield of transformants increased 100-fold when pIJ702 was modified by passage in Chainia. Because the plasmid replicon was functional in Chainia and the modified plasmid was stably maintained, the transformation system should be useful for self-cloning in Chainia NCL 82-5-1 of the many commercially important enzymes this strain is known to produce. Key words: Chainia, transformation, Streptomyces, pIJ702 restriction modification, heat attenuation.

Genetic Competence and Transformation in Oral Streptococci

2001 ◽  
Vol 12 (3) ◽  
pp. 217-243 ◽  
Author(s):  
D.G. Cvitkovitch
Keyword(s):  
Genetic Transformation ◽  
Genetic Information ◽  
Physiological State ◽  
Oral Streptococci ◽  
Dna Uptake ◽  
Genetic Competence ◽  
Gram Positive Bacteria ◽  
Oral Biofilms ◽  
Foreign Dna ◽  
Natural Genetic Transformation

The oral streptococci are normally non-pathogenic residents of the human microflora. There is substantial evidence that these bacteria can, however, act as "genetic reservoirs" and transfer genetic information to transient bacteria as they make their way through the mouth, the principal entry point for a wide variety of bacteria. Examples that are of particular concern include the transfer of antibiotic resistance from oral streptococci to Streptococcus pneumoniae. The mechanisms that are used by oral streptococci to exchange genetic information are not well-understood, although several species are known to enter a physiological state of genetic competence. This state permits them to become capable of natural genetic transformation, facilitating the acquisition of foreign DNA from the external environment. The oral streptococci share many similarities with two closely related Gram-positive bacteria. S. pneumoniae and Bacillus subtilis. In these bacteria, the mechanisms of quorum-sensing, the development of competence, and DNA uptake and integration are well-charaterized. Using this knowledge and the data available in genome databases allowed us to identify putative genes involved in these processes in the oral organism Streptococcus mutans. Models of competence development and genetic transformation in the oral streptococci and strategies to confirm these models are discussed. Future studies of competence in oral biofilms, the natural environment of oral streptococci, will be discussed.

scholarly journals Manganese mutagenesis in yeast: II. Conditions of induction and characteristics of mitochondrial respiratory deficientSaccharomyces cerevisiaemutants induced with manganese and cobalt

1975 ◽  
Vol 26 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Wieslawa Prazmo ◽  
Ewa Balbin ◽  
Hanna Baranowska ◽  
Anna Ejchart ◽  
Aleksandra Putrament
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Drug Resistance ◽  
Mitochondrial Dna ◽  
Cell Density ◽  
Considerable Proportion ◽  
Mutagenic Action ◽  
Resistance Markers ◽  
Low Efficiency ◽  
Mitochondrial Respiratory

SUMMARYManganese and cobalt are capable of inducing ρ−mutations* in non-growing cells ofSaccharomyces cerevisiae, but their mutagenic action is much stronger in growing cells. At a given concentration cobalt and manganese can be either strongly mutagenic or non-mutagenic, depending on the cell density.Most of the ρ−mutants induced with manganese and a considerable proportion of those induced with cobalt are suppressive and/or transmit drug resistance markers, so they must still carry mitochondrial DNA. Cobalt can decrease suppressiveness with low efficiency and eliminate drug resistance markers from established ρ−clones.

scholarly journals A cucumber green mottle mosaic virus vector for virus-induced gene silencing in cucurbit plants

2019 ◽  
Author(s):  
Mei Liu ◽  
Zhiling Liang ◽  
Miguel A. Aranda ◽  
Ni Hong ◽  
Liming Liu ◽  
...  
Keyword(s):  
Genetic Transformation ◽  
Gene Silencing ◽  
Mosaic Virus ◽  
Gene Function ◽  
Nicotiana Benthamiana ◽  
Phytoene Desaturase ◽  
Virus Induced Gene Silencing ◽  
Economic Significance ◽  
Potential Alternative ◽  
Low Efficiency

AbstractCucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, however genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiencies. Virus-induced gene silencing (VIGS) is a potential alternative tool. So far, very few ideal VIGS vectors are available for cucurbits. Here, we describe a new VIGS vector derived from cucumber green mottle mosaic virus (CGMMV), a monopartite virus that infects cucurbits naturally. We show that the CGMMV vector is competent to induce efficient silencing of the phytoene desaturase (PDS) gene in the model plant Nicotiana benthamiana and in cucurbits, including watermelon, melon, cucumber and bottle gourd. Infection with the CGMMV vector harboring PDS sequences of 69-300 bp in length in the form of sense-oriented or hairpin cDNAs resulted in photobleaching phenotypes in N. benthamiana and cucurbits by PDS silencing. Additional results reflect that silencing of the PDS gene could persist for over two months and the silencing effect of CGMMV-based vectors could be passaged. These results demonstrate that CGMMV vector could serve as a powerful and easy-to-use tool for characterizing gene function in cucurbits.One sentence summaryA CGMMV-based vector enables gene function studies in cucurbits, an extremely low efficiency species for genetic transformation.

Non-coding RNAs as Novel Biomarkers in Cancer Drug Resistance

2021 ◽  
Vol 28 ◽  
Author(s):  
Haixiu Yang ◽  
Changlu Qi ◽  
Boyan Li ◽  
Liang Cheng
Keyword(s):  
Drug Resistance ◽  
Computational Methods ◽  
Cell Cycle Progression ◽  
Epithelial To Mesenchymal Transition ◽  
Cancer Drug ◽  
Mesenchymal Transition ◽  
Treatment Regimens ◽  
Anticancer Treatment ◽  
Non Coding Rnas ◽  
Low Efficiency

: Chemotherapy is often the primary and most effective anticancer treatment; however, drug resistance remains a major obstacle to it being curative. Recent studies have demonstrated that non-coding RNAs (ncRNAs), especially microRNAs and long non-coding RNAs, are involved in drug resistance of tumor cells in many ways, such as modulation of apoptosis, drug efflux and metabolism, epithelial-to-mesenchymal transition, DNA repair, and cell cycle progression. Exploring the relationships between ncRNAs and drug resistance will not only contribute to our understanding of the mechanisms of drug resistance and provide ncRNA biomarkers of chemoresistance, but will also help realize personalized anticancer treatment regimens. Due to the high cost and low efficiency of biological experimentation, many researchers have opted to use computational methods to identify ncRNA biomarkers associated with drug resistance. In this review, we summarize recent discoveries related to ncRNA-mediated drug resistance and highlight the computational methods and resources available for ncRNA biomarkers involved in chemoresistance.

scholarly journals An Unstable Competence-Induced Protein, CoiA, Promotes Processing of Donor DNA after Uptake during Genetic Transformation in Streptococcus pneumoniae

2006 ◽  
Vol 188 (14) ◽  
pp. 5177-5186 ◽  
Author(s):  
Bhushan V. Desai ◽  
Donald A. Morrison
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Transcriptional Activation ◽  
Response Regulator ◽  
Specific Response ◽  
Dna Uptake ◽  
Gram Positive Bacteria ◽  
Specific Alternative ◽  
Natural Genetic Transformation

ABSTRACT Natural genetic transformation in Streptococcus pneumoniae entails transcriptional activation of at least two sets of genes. One set of genes, activated by the competence-specific response regulator ComE, is involved in initiating competence, whereas a second set is activated by the competence-specific alternative sigma factor ComX and functions in DNA uptake and recombination. Here we report an initial characterization of CoiA, a ComX-dependent gene product that is induced during competence and is required for transformation. CoiA is widely conserved among gram-positive bacteria, and in streptococci, the entire coiA locus composed of four genes is conserved. By use of immunoblot assay, we show that, similar to its message, CoiA protein is transient, appearing at 10 min and largely disappearing by 30 min post-competence induction. Using complementation analysis, we establish that coiA is the only gene of this induced locus needed for transformability. We find no indication of CoiA having a role in regulating competence. Finally, using 32P- and 3H-labeled donor DNA, we demonstrate that a coiA mutant can internalize normal amounts of donor DNA compared to the wild-type strain but is unable to process it into viable transformants, suggesting a role for CoiA after DNA uptake, either in DNA processing or recombination.

scholarly journals Pseudomonas stutzeri Has Two Closely RelatedpilA Genes (Type IV Pilus Structural Protein) with Opposite Influences on Natural Genetic Transformation

2001 ◽  
Vol 183 (7) ◽  
pp. 2359-2366 ◽  
Author(s):  
Stefan Graupner ◽  
Wilfried Wackernagel
Keyword(s):  
Genetic Transformation ◽  
Pseudomonas Stutzeri ◽  
Leader Peptide ◽  
Duplex Dna ◽  
Dna Uptake ◽  
Structural Protein ◽  
Dichelobacter Nodosus ◽  
Type Iv ◽  
Insertional Inactivation ◽  
Natural Genetic Transformation

ABSTRACT Pseudomonas stutzeri has type IV pili for which the pilA gene (here termed pilAI) provides the structural protein and which are required for DNA uptake and natural genetic transformation. Downstream of pilAIwe identified a gene, termed pilAII, coding for a deduced protein with a size similar to that of PilAI with 55% amino acid sequence identity and with a typical leader peptide including a leader peptidase cleavage site. Fusions to lacZ revealed that pilAII is expressed only about 10% compared topilAI, although the genes are cotranscribed as shown by reverse transcription-PCR. Surprisingly, insertional inactivation ofpilAII produced a hypertransformation phenotype giving about 16-fold-increased transformation frequencies. Hypertransformation also occurred in pilAI pilAII double mutants expressing heterologous pilA genes of nontransformable bacteria, like Pseudomonas aeruginosa or Dichelobacter nodosus. The overexpression of pilAII decreased transformation up to 5,000-fold compared to that of thepilAII mutant. However, neither inactivation ofpilAII nor its overexpression affected the amounts of [3H]thymidine-labeled DNA that were competence-specifically bound and taken up by the cells. In thepilAII mutant, the transformation by purified single-stranded DNA (which depends on comA andexbB, as does transformation by duplex DNA) was also increased 17-fold. It is concluded that PilAII suppresses a step in transformation after the uptake of duplex DNA into the cell and perhaps before its translocation into the cytoplasm. The idea that the degree of the transformability of cells could be permanently adjusted by the expression level of an antagonistic protein is discussed.

The preparation of transforming DNA from Mycoplasma hominis strain Sprott tetr and quantitative studies of the factors affecting the genetic transformation of Mycoplasma salivarium strain S9 tets to tetracycline resistance

1980 ◽  
Vol 26 (9) ◽  
pp. 1147-1152 ◽  
Author(s):  
Anna M. Cerone-McLernon ◽  
Geoffrey Furness
Keyword(s):  
Genetic Transformation ◽  
Tetracycline Resistance ◽  
Mycoplasma Hominis ◽  
Dna Uptake ◽  
Optimum Conditions ◽  
Factors Affecting ◽  
Quantitative Studies ◽  
Viable Cells ◽  
Calf Thymus

DNA extracted by a standard method from Mycoplasma hominis Sprott, resistant to 100 μg tetracycline, permitted the quantitative genetic transformation of tetracycline-sensitive Mycoplasma salivarium to resistance. The yield was 1 μg DNA/109 cells. This DNA enabled determination of the optimum conditions for making M. salivarium competent with CaCl2 and for studying some factors affecting transformation. Mycoplasma salivarium was transformed to resistance to 10, 20, and 30 μg tetracycline but not to 40 μg. The optimum DNA concentration for transforming resistance to 10, 20, and30 μg tetracycline was the same, i.e., 50 μg DNA/108 viable cells. Treatment with DNase indicated that DNA uptake took 30 min. Competition between transforming DNA and DNA from calf thymus and M. salivarium tets inhibited transformation.

Specificity of DNA uptake in genetic transformation of gonococci

1979 ◽  
Vol 86 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Thomas J. Dougherty ◽  
Anneleen Asmus ◽  
Alexander Tomasz
Keyword(s):  
Genetic Transformation ◽  
Dna Uptake
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