The Central Importance of E. coli and λ‎ Phage in the New Molecular Biology

2021 ◽  
pp. 130-135
Author(s):  
Thomas E. Schindler
Keyword(s):  
Molecular Biology ◽  
Genetic Recombination ◽  
Model Organism ◽  
Restriction Enzymes ◽  
Model Organisms ◽  
Host Restriction ◽  
E Coli ◽  
Jumping Genes ◽  
K 12 ◽  
Convenient Model

This chapter considers two of the most important legacies of the Lederbergs’ pioneering work: the discoveries of the model organisms that would dominate molecular biology, E. coli and λ‎ bacteriophage. The Lederbergs’ introduction of E. coli as a convenient model organism shifted the direction of molecular genetics. Barbara McClintock’s discovery of jumping genes remained unappreciated for decades, until the field of molecular biology caught up to validate her transposable elements in bacteria. The discovery of restriction enzymes—the molecular scissors for precisely cutting DNA at specific sites, a prerequisite for genetic recombination techniques—emphasized the versatility of bacteriophage λ‎ as a powerful experimental tool. The discovery of specialized transduction by Larry Morse and Esther Lederberg hinted at the mechanisms of “host restriction.” Werner Arber and Daisy Dussoix discovered restriction endonucleases by building upon Esther Lederberg’s research with λ‎ phage and the differences between E. coli B and K-12.

scholarly journals Homeostasis in the Central Dogma of Molecular Biology: the importance of mRNA instability

2019 ◽  
Author(s):  
José E. Pérez-Ortín ◽  
Vicente Tordera ◽  
Sebastián Chávez
Keyword(s):  
Molecular Biology ◽  
Model Organism ◽  
Model Organisms ◽  
Published Data ◽  
Central Dogma ◽  
E Coli ◽  
Response Capacity ◽  
Cultured Human Cells ◽  
The Cost

AbstractCell survival requires the control of biomolecule concentration, i.e. biomolecules should approach homeostasis. With information-carrying macromolecules, the particular concentration variation ranges depend on each type: DNA is not buffered, but mRNA and protein concentrations are homeostatically controlled, which leads to the ribostasis and proteostasis concepts. In recent years, we have studied the particular features of mRNA ribostasis and proteostasis in the model organismS. cerevisiae. Here we extend this study by comparing published data from three other model organisms:E. coli, S. pombeand cultured human cells. We describe how mRNA ribostasis is less strict than proteostasis. A constant ratio appears between the average decay and dilution rates during cell growth for mRNA, but not for proteins. We postulate that this is due to a trade-off between the cost of synthesis and the response capacity. This compromise takes place at the transcription level, but is not possible at the translation level as the high stability of proteins,versusthat of mRNAs, precludes it. We hypothesize that the middle-place role of mRNA in theCentral Dogmaof Molecular Biology and its chemical instability make it more suitable than proteins for the fast changes needed for gene regulation.Graphical Abstract

THE INFLUENCE OF THE PO1A1 MUTATION UPON RECOMBINATION IN ESCHERICHIA COLI K12

1979 ◽  
Vol 21 (3) ◽  
pp. 423-428 ◽  
Author(s):  
Barry W. Glickman ◽  
Tineke Rutgers
Keyword(s):  
Escherichia Coli ◽  
Dna Polymerase ◽  
Genetic Recombination ◽  
Dna Polymerase I ◽  
Multiple Gene ◽  
E Coli ◽  
Recombinational Process ◽  
K 12 ◽  
Polymerase I

Genetic recombination in Escherichia coli is a highly regulated process involving multiple gene products. We have investigated the role of DNA polymerase I in this process by studying the effect of the po1A1 mutation upon DNA transfer and conjugation in otherwise isogenic suppressor-free strains of E. coli K-12. It was found that the po1A1 mutation greatly reduces recombination in Hfr crosses (a factor of 20 in Po1+ × Po1A1 crosses and more than a factor of 100 in Po1A1 × Po1A1 crosses). However, since the po1A1 mutation reduces the strains capacity to act as a recipient for an F-prime and the analysis of recombination transfer gradients revealed no differences between Po1+ and Po1− strains, it is concluded that DNA polymerase I probably affects the transfer and/or stability of donor DNA rather than the recombinational process itself.

scholarly journals Penyisipan Gen Inhibitor α-amilase pada Plasmid Biner pCambia 1301

2016 ◽  
Vol 1 (2) ◽  
pp. 45
Author(s):  
Edy Listanto ◽  
Sutrisno Sutrisno ◽  
Saptowo J. Pardal ◽  
M. Herman
Keyword(s):  
Molecular Biology ◽  
Research And Development ◽  
Genetic Resources ◽  
Restriction Enzymes ◽  
Restriction Pattern ◽  
E Coli ◽  
Colony Number ◽  
The Right ◽  
Biology Laboratory ◽  
Binary Plasmid

<p class="p1">The experiment was conducted at the Molecular Biology Laboratory of the Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development, Bogor. The objective was to construct <em>-ai </em>gene on a binary plasmid <em>p</em>Cambia 1301. This experiment was carried out using construction method by ligation process between fragments of <em>α-ai </em>gene from <em>p</em>TA<span class="s1">3 </span>plasmid and <em>p</em>Cambia 1301 on <em>Hind</em>III site. The result of ligant transformation into <em>E. coli </em>DH5<em>α </em>was 182 surviving colonies on YEP medium containing kanamycin. DNA samples were obtained from 60 randomly selected colonies. The restriction pattern was tested by digesting each DNA sample using <em>Hind</em>III showed colonies containing two fragments expected of sizes wich are 11.837 and 4.887 kb. Two colonies are predicted containing of <em>α-ai </em>gene on its the binary plasmid. Advanced tests using restriction enzymes <em>Bam</em>HI and <em>Xba</em>I showed two directions (right and left) of <em>α-ai </em>gene. The right direction was shown by <em>p</em>Cambia-<em>α-ai</em>1 from colony number 43. This plasmid showed expected fragments of sizes 13.485 and 3.219 kb when digested with <em>Bam</em>HI and two fragments of sizes 15.421 and 1.303 kb when digested with <em>Xba</em>I. The left direction was shown <em>p</em>Cambia-<em>α-ai</em>2 from colony number 58. This plasmid also demon-strated expected fragments of sizes 15.026 and 1.698 kb when digested with <em>Bam</em>HI and two fragments of sizes 13.082 and 3.642 kb when digested with <em>Xba</em>I. Both <em>p</em>Cambia-<em>α-ai</em>1 and <em>p</em>Cambia-<em>α-ai</em>2 were transformed into <em>A. tumefaciens </em>LBA4404.</p>

Graduate School

2021 ◽  
pp. 31-36
Author(s):  
Thomas E. Schindler
Keyword(s):  
Graduate School ◽  
Teaching Assistant ◽  
Model Organisms ◽  
Palo Alto ◽  
Bacterial Strains ◽  
Graduate Course ◽  
E Coli ◽  
One Year ◽  
Breakthrough Experiments ◽  
K 12

This chapter relates how Esther Zimmer began working in bacteriology. At the beginning of September 1944, twenty-one-year old Esther Zimmer set off on a solitary four-day train journey to Palo Alto, California. Soon after arriving she met Edward Tatum, who was so impressed with her understanding of genetics that he invited her to be his teaching assistant in the graduate course in genetics. During the summer between her first and second years in graduate school, Zimmer took two courses in bacteriology taught by Cornelius van Niel. His bacteriology courses inspired a generation of molecular biologists and energized Zimmer’s engagement with bacteria, the model organisms that she would study for the rest of her scientific career. Back at Palo Alto, during the fall of 1945, she prepared the mutant bacterial strains of E. coli K-12 that Joshua Lederberg would use for his breakthrough experiments in bacterial conjugation.

scholarly journals Towards a unified resource for transcriptional regulation inEscherichia coliK-12: Incorporating high throughput-generated binding data within the classic framework of regulation of initiation of transcription in RegulonDB

2017 ◽  
Author(s):  
Alberto Santos-Zavaleta ◽  
Mishael Sánchez-Pérez ◽  
Heladia Salgado ◽  
David A. Velázquez-Ramírez ◽  
Socorro Gama-Castro ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Molecular Biology ◽  
High Throughput ◽  
Expression Profiles ◽  
Regulation Of Gene Expression ◽  
Controlled Vocabulary ◽  
Data Set ◽  
E Coli ◽  
K 12

ABSTRACTOur understanding of the regulation of gene expression has been strongly benefited by the availability of high throughput technologies that enable questioning the whole genome for the binding of specific transcription factors and expression profiles. In the case of genome models, such asEscherichia coliK-12, this knowledge needs to be integrated with the legacy of accumulated genetics and molecular biology pre-genomic knowledge in order to attain deeper levels in the understanding of their biology. In spite of the several repositories and curated databases, there is no effort, nor electronic site yet, to comprehensively integrate the available knowledge from all these different sources around the regulation of gene expression ofE. coliK-12. In this paper, we describe a first effort to expand RegulonDB, the database containing the rich legacy of decades of classic molecular biology experiments supporting what we know about gene regulation and operon organization inE. coliK-12, to include the genome-wide data set collections from 25 ChIP and 18 gSELEX publications, respectively, in addition to around 60 expression profiles used in their curation. Three essential features for the integration of this information coming from different methodological approaches are; first, a controlled vocabulary within an ontology for precisely defining growth conditions, second, the criteria to separate elements with enough evidence to consider them involved in gene regulation from isolated sites, and third, an expanded computational model supporting this knowledge. Altogether, this constitutes the basis for adequately gathering and enabling the comparisons and integration strongly needed to manage and access such wealth of knowledge. This version of RegulonBD is a first step toward what should become the unifying access point for current and future knowledge on gene regulation inE. coliK-12. Furthermore, this model platform and associated methodologies and criteria, can well be emulated for gathering knowledge on other microbial organisms.

scholarly journals SOME GENETIC CONSEQUENCES OF CHANGES IN THE LEVEL OF recA GENE FUNCTION IN ESCHERICHIA COLI K-12

Genetics ◽  
1976 ◽  
Vol 84 (4) ◽  
pp. 675-695
Author(s):  
Robert G Lloyd ◽  
Brooks Low
Keyword(s):  
Escherichia Coli ◽  
Gene Function ◽  
Genetic Recombination ◽  
Unit Length ◽  
Reca Gene ◽  
E Coli ◽  
Low Level ◽  
Transfer Origin ◽  
K 12

ABSTRACT Genetic recombination was studied in E. coli mutants that carry lesions in the recA gene but retain some capacity for generating recombinant progeny. We observed that recombination was detectable only at a very low level during the incubation of leaky RecA- merozygotes in broth. However, recombination appeared to occur at much higher frequencies when recombinant progeny were assayed by selection on minimal agar. Analysis of the recombinants obtained with Hfr donors revealed a deficiency of multiple exchanges per unit length of DNA in leaky RecA- strains. In many of these crosses recombinants that inherited donor alleles close to the transfer origin were much reduced in frequency, except when the recipient was also RecB-.

scholarly journals Tracy Morton Sonneborn, 19 October 1905 - 26 January 1981

1982 ◽  
Vol 28 ◽  
pp. 537-574 ◽  
Keyword(s):  
Escherichia Coli ◽  
Molecular Biology ◽  
Genetic Recombination ◽  
Genetic Research ◽  
Sexual Cycle ◽  
Mating Types ◽  
Research Assistant ◽  
E Coli ◽  
Living Things ◽  
Modern Molecular Biology

The explosive development of genetics and molecular biology that we are now witnessing had its origin, some 40 years ago, in the introduction into genetic research of microorganisms. Compared with the higher animals and plants which had been used previously— Drosophila , maize, mice, etc.— microorganisms had many technical advantages, and as everyone knows, since then genetics has advanced prodigiously. Moreover, in spite of the extraordinary complexity of modern molecular biology, one thing stands out: basically the same genetic principles apply to the whole range of living things, from viruses to man. Everywhere the nuclear elements —ultimately DNA—play an overwhelmingly important role. The microorganisms first used in genetic research were a fungus— Neurospora ,a bacterium— Escherichia coli , and the bacteriophages of E. coli . However, long before these were used, another group of microorganisms—the protozoa—had been considered as potentially suitable. They were unicellular, and unlike bacteria, often had a regular sexual cycle. H. S. Jennings tried for many years to do genetics with the ciliate Paramecium but had little success, owing to difficulties in making controlled hybridizations between genetically diverse lines—an essential minimum desideratum for classical genetic work. In 1930 Jennings employed a young research assistant, T. M. Sonneborn, for the Paramecium work, and as a result, after 7 years, mating types were discovered in P. aurelia . Thereafter genetics along Mendelian lines with the organism became technically feasible. This was ten years before Lederberg and Tatum demonstrated that genetic recombination could occur in E. coli .

Electron Microscopy and image analysis of nucleo-protein complexes

1994 ◽  
Vol 52 ◽  
pp. 88-89
Author(s):  
E. H. Egelman ◽  
X. Yu
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Normal Cell ◽  
Genetic Recombination ◽  
Protein Complexes ◽  
Chromosomal Rearrangements ◽  
Reca Protein ◽  
E Coli ◽  
Helical Polymer ◽  
Specific Protease

The RecA protein of E. coli has been shown to mediate genetic recombination, regulate its own synthesis, control the expression of other genes, act as a specific protease, form a helical polymer and have an ATPase activity, among other observed properties. The unusual filament formed by the RecA protein on DNA has not previously been shown to exist outside of bacteria. Within this filament, the 36 Å pitch of B-form DNA is extended to about 95 Å, the pitch of the RecA helix. We have now establishedthat similar nucleo-protein complexes are formed by bacteriophage and yeast proteins, and availableevidence suggests that this structure is universal across all of biology, including humans. Thus, understanding the function of the RecA protein will reveal basic mechanisms, in existence inall organisms, that are at the foundation of general genetic recombination and repair.Recombination at this moment is assuming an importance far greater than just pure biology. The association between chromosomal rearrangements and neoplasms has become stronger and stronger, and these rearrangements are most likely products of the recombinatory apparatus of the normal cell. Further, damage to DNA appears to be a major cause of cancer.

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