scholarly journals The Transcriptional Switch of Bacteriophage WΦ, a P2-Related but Heteroimmune Coliphage

1999 ◽  
Vol 73 (12) ◽  
pp. 9816-9826 ◽  
Author(s):  
Tao Liu ◽  
Elisabeth Haggård-Ljungquist
Keyword(s):  
Integration Site ◽  
Site Directed Mutagenesis ◽  
Structural Proteins ◽  
Direct Repeats ◽  
Recognition Sequence ◽  
Face To Face ◽  
The Core ◽  
Transcriptional Switch ◽  
Genes Encoding ◽  
K 12

ABSTRACT Phage WΦ is a member of the nonlambdoid P2 family of temperate phages. The DNA sequence of the whole early-control region and theint and attP region of phage WΦ has been determined. The phage integration site was located at 88.6 min of theEscherichia coli K-12 map, where a 47-nucleotide sequence was found to be identical in the host and phage genomes. The WΦ Int protein belongs to the Int family of site-specific recombinases, and it seems to have the same arm binding recognition sequence as P2 Int, but the core sequence differs. The transcriptional switch contains two face-to-face promoters, Pe and Pc, and two repressors, C and Cox, controlling Pe and Pc, respectively. The early Pe promoter was found to be much stronger than the Pc promoter. Furthermore, the Pe transcript was shown to interfere with Pc transcription. By site-directed mutagenesis, the binding site of the immunity repressor was located to two direct repeats spanning the Pe promoter. A point mutation in one or the other repeat does not affect repression by C, but when it is included in both, C has no effect on the Pe promoter. The Cox repressor efficiently blocks expression from the Pc promoter, but its DNA recognition sequence was not evident. Most members of the P2 family of phages are able to function as helpers for satellite phage P4, which lacks genes encoding structural proteins and packaging and lysis functions. In this work it is shown that P4 E, known to function as an antirepressor by binding to P2 C, also turns the transcriptional switch of WΦ from the lysogenic to the lytic mode. However, in contrast to P2 Cox, WΦ Cox is unable to activate the P4 Pll promoter.

Exposure of protein VP7 on the surface of bluetongue virus

1990 ◽  
Vol 48 (3) ◽  
pp. 600-601
Author(s):  
A.D. Hyatt
Keyword(s):  
Bluetongue Virus ◽  
Structural Proteins ◽  
Major Constituent ◽  
Outer Coat ◽  
Virus Particles ◽  
Antibody Recognition ◽  
The Core ◽  
The Family ◽  
Electron Microscopical ◽  
Physical Accessibility

Bluetongue virus (BTV) is the type species os the genus orbivirus in the family Reoviridae. The virus has a fibrillar outer coat containing two major structural proteins VP2 and VP5 which surround an icosahedral core. The core contains two major proteins VP3 and VP7 and three minor proteins VP1, VP4 and VP6. Recent evidence has indicated that the core comprises a neucleoprotein center which is surrounded by two protein layers; VP7, a major constituent of capsomeres comprises the outer and VP3 the inner layer of the core . Antibodies to VP7 are currently used in enzyme-linked immunosorbant assays and immuno-electron microscopical (JEM) tests for the detection of BTV. The tests involve the antibody recognition of VP7 on virus particles. In an attempt to understand how complete viruses can interact with antibodies to VP7 various antibody types and methodologies were utilized to determine the physical accessibility of the core to the external environment.

scholarly journals Identification and Characterization of the Genes Encoding the Core Histones and Histone Variants of Neurospora crassa

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 961-973 ◽  
Author(s):  
Shan M Hays ◽  
Johanna Swanson ◽  
Eric U Selker
Keyword(s):  
Neurospora Crassa ◽  
Histone Variants ◽  
Null Alleles ◽  
Histone Genes ◽  
Histone H4 ◽  
Coding Regions ◽  
The Core ◽  
Genomic Arrangement ◽  
Genes Encoding ◽  
Core Histones

Abstract We have identified and characterized the complete complement of genes encoding the core histones of Neurospora crassa. In addition to the previously identified pair of genes that encode histones H3 and H4 (hH3 and hH4-1), we identified a second histone H4 gene (hH4-2), a divergently transcribed pair of genes that encode H2A and H2B (hH2A and hH2B), a homolog of the F/Z family of H2A variants (hH2Az), a homolog of the H3 variant CSE4 from Saccharomyces cerevisiae (hH3v), and a highly diverged H4 variant (hH4v) not described in other species. The hH4-1 and hH4-2 genes, which are 96% identical in their coding regions and encode identical proteins, were inactivated independently. Strains with inactivating mutations in either gene were phenotypically wild type, in terms of growth rates and fertility, but the double mutants were inviable. As expected, we were unable to isolate null alleles of hH2A, hH2B, or hH3. The genomic arrangement of the histone and histone variant genes was determined. hH2Az and the hH3-hH4-1 gene pair are on LG IIR, with hH2Az centromere-proximal to hH3-hH4-1 and hH3 centromere-proximal to hH4-1. hH3v and hH4-2 are on LG IIIR with hH3v centromere-proximal to hH4-2. hH4v is on LG IVR and the hH2A-hH2B pair is located immediately right of the LG VII centromere, with hH2A centromere-proximal to hH2B. Except for the centromere-distal gene in the pairs, all of the histone genes are transcribed toward the centromere. Phylogenetic analysis of the N. crassa histone genes places them in the Euascomycota lineage. In contrast to the general case in eukaryotes, histone genes in euascomycetes are few in number and contain introns. This may be a reflection of the evolution of the RIP (repeat-induced point mutation) and MIP (methylation induced premeiotically) processes that detect sizable duplications and silence associated genes.

scholarly journals Ribose 5-phosphate isomerase type B from Trypanosoma cruzi: kinetic properties and site-directed mutagenesis reveal information about the reaction mechanism

2006 ◽  
Vol 401 (1) ◽  
pp. 279-285 ◽  
Author(s):  
Ana L. Stern ◽  
Emmanuel Burgos ◽  
Laurent Salmon ◽  
Juan J. Cazzulo
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Pentose Phosphate ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Kinetic Properties ◽  
Type B ◽  
Nucleotide Synthesis ◽  
Gene Coding ◽  
Genes Encoding

Trypanosoma cruzi, the human parasite that causes Chagas disease, contains a functional pentose phosphate pathway, probably essential for protection against oxidative stress and also for R5P (ribose 5-phosphate) production for nucleotide synthesis. The haploid genome of the CL Brener clone of the parasite contains one gene coding for a Type B Rpi (ribose 5-phosphate isomerase), but genes encoding Type A Rpis, most frequent in eukaryotes, seem to be absent. The RpiB enzyme was expressed in Escherichia coli as a poly-His tagged active dimeric protein, which catalyses the reversible isomerization of R5P to Ru5P (ribulose 5-phos-phate) with Km values of 4 mM (R5P) and 1.4 mM (Ru5P).4-Phospho-D-erythronohydroxamic acid, an analogue to the reaction intermediate when the Rpi acts via a mechanism involving the formation of a 1,2-cis-enediol, inhibited the enzyme competi-tively, with an IC50 value of 0.7 mM and a Ki of 1.2 mM. Site-directed mutagenesis allowed the demonstration of a role for His102, but not for His138, in the opening of the ribose furanosic ring. A major role in catalysis was confirmed for Cys69, since the C69A mutant was inactive in both forward and reverse directions of the reaction. The present paper contributes to the know-ledge of the mechanism of the Rpi reaction; in addition, the absence of RpiBs in the genomes of higher animals makes this enzyme a possible target for chemotherapy of Chagas disease.

scholarly journals Molecular cloning of cellular genes encoding retinoblastoma-associated proteins: identification of a gene with properties of the transcription factor E2F.

1992 ◽  
Vol 12 (12) ◽  
pp. 5620-5631 ◽  
Author(s):  
B Shan ◽  
X Zhu ◽  
P L Chen ◽  
T Durfee ◽  
Y Yang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mammalian Cells ◽  
Leucine Zipper ◽  
T Antigen ◽  
Transactivation Domain ◽  
Recognition Sequence ◽  
Cellular Genes ◽  
Genes Encoding ◽  
Associated Proteins ◽  
Transcription Factor E2f

The retinoblastoma protein interacts with a number of cellular proteins to form complexes which are probably crucial for its normal physiological function. To identify these proteins, we isolated nine distinct clones by direct screening of cDNA expression libraries using purified RB protein as a probe. One of these clones, Ap12, is expressed predominantly at the G1-S boundary and in the S phase of the cell cycle. The nucleotide sequence of Ap12 has features characteristic of transcription factors. The C-terminal region binds to unphosphorylated RB in regions similar to those to which T antigen binds and contains a transactivation domain. A region containing a potential leucine zipper flanked by basic residues is able to bind an E2F recognition sequence specifically. Expression of Ap12 in mammalian cells significantly enhances E2F-dependent transcriptional activity. These results suggest that Ap12 encodes a protein with properties known to be characteristic of transcription factor E2F.

scholarly journals First Staphylococcal Cassette ChromosomemecContaining amecB-Carrying Gene Complex Independent of Transposon Tn6045in a Macrococcus caseolyticus Isolate from a Canine Infection

2015 ◽  
Vol 59 (8) ◽  
pp. 4577-4583 ◽  
Author(s):  
Elena Gómez-Sanz ◽  
Sybille Schwendener ◽  
Andreas Thomann ◽  
Stefanie Gobeli Brawand ◽  
Vincent Perreten
Keyword(s):  
Integration Site ◽  
Direct Repeat ◽  
Open Reading Frames ◽  
Gene Complex ◽  
Direct Repeats ◽  
Content Type ◽  
Canine Infection ◽  
The Right ◽  
Lactamase Gene ◽  
Reading Frames

ABSTRACTA methicillin-resistantmecB-positiveMacrococcus caseolyticus(strain KM45013) was isolated from the nares of a dog with rhinitis. It contained a novel 39-kb transposon-defective completemecB-carrying staphylococcal cassette chromosomemecelement (SCCmecKM45013). SCCmecKM45013contained 49 coding sequences (CDSs), was integrated at the 3′ end of the chromosomalorfXgene, and was delimited at both ends by imperfect direct repeats functioning as integration site sequences (ISSs). SCCmecKM45013presented two discontinuous regions of homology (SCCmeccoverage of 35%) to the chromosomal and transposon Tn6045-associated SCCmec-like element ofM. caseolyticusJCSC7096: (i) themecgene complex (98.8% identity) and (ii) theccr-carrying segment (91.8% identity). Themecgene complex, located at the right junction of the cassette, also carried the β-lactamase geneblaZm(mecRm-mecIm-mecB-blaZm). SCCmecKM45013contained two cassette chromosome recombinase genes,ccrAm2andccrBm2, which shared 94.3% and 96.6% DNA identity with those of the SCCmec-like element of JCSC7096 but shared less than 52% DNA identity with the staphylococcalccrABandccrCgenes. Three distinct extrachromosomal circularized elements (the entire SCCmecKM45013, ΨSCCmecKM45013lacking theccrgenes, and SCCKM45013lackingmecB) flanked by one ISS copy, as well as the chromosomal regions remaining after excision, were detected. An unconventional circularized structure carrying themecBgene complex was associated with two extensive direct repeat regions, which enclosed two open reading frames (ORFs) (ORF46 and ORF51) flanking the chromosomalmecB-carrying gene complex. This study revealedM. caseolyticusas a potential disease-associated bacterium in dogs and also unveiled an SCCmecelement carryingmecBnot associated with Tn6045in the genusMacrococcus.

scholarly journals The pentose phosphate pathway in Trypanosoma cruzi: a potential target for the chemotherapy of Chagas disease

2007 ◽  
Vol 79 (4) ◽  
pp. 649-663 ◽  
Author(s):  
Mariana Igoillo-Esteve ◽  
Dante Maugeri ◽  
Ana L. Stern ◽  
Paula Beluardi ◽  
Juan J. Cazzulo
Keyword(s):  
Oxidative Stress ◽  
Trypanosoma Cruzi ◽  
Pentose Phosphate Pathway ◽  
Single Copy ◽  
Pentose Phosphate ◽  
Site Directed Mutagenesis ◽  
Haploid Genome ◽  
Salt Bridges ◽  
Phosphogluconate Dehydrogenase ◽  
Genes Encoding

Trypanosoma cruzi is highly sensitive to oxidative stress caused by reactive oxygen species. Trypanothione, the parasite's major protection against oxidative stress, is kept reduced by trypanothione reductase, using NADPH; the major source of the reduced coenzyme seems to be the pentose phosphate pathway. Its seven enzymes are present in the four major stages in the parasite's biological cycle; we have cloned and expressed them in Escherichia coli as active proteins. Glucose 6-phosphate dehydrogenase, which controls glucose flux through the pathway by its response to the NADP/NADPH ratio, is encoded by a number of genes per haploid genome, and is induced up to 46-fold by hydrogen peroxide in metacyclic trypomastigotes. The genes encoding 6-phosphogluconolactonase, 6-phosphogluconate dehydrogenase, transaldolase and transketolase are present in the CL Brener clone as a single copy per haploid genome. 6-phosphogluconate dehydrogenase is very unstable, but was stabilized introducing two salt bridges by site-directed mutagenesis. Ribose-5-phosphate isomerase belongs to Type B; genes encoding Type A enzymes, present in mammals, are absent. Ribulose-5-phosphate epimerase is encoded by two genes. The enzymes of the pathway have a major cytosolic component, although several of them have a secondary glycosomal localization, and also minor localizations in other organelles.

Technology Imperative in Managerial Decision-Making

2014 ◽  
pp. 158-176 ◽  
Author(s):  
Neeta Baporikar
Keyword(s):  
Decision Making ◽  
Decision Makers ◽  
Limited Information ◽  
Managerial Decision ◽  
Managerial Decision Making ◽  
Face To Face ◽  
The Core ◽  
Use Of Technology ◽  
Management Approaches ◽  
Virtual Setting

Decisions can make or mar an organization. Decision-making is a multifaceted and intricate process. This process becomes even more complicated and complex when it comes to organizations, especially in this competitive world. Today, decisions are made not only under uncertainty, with available and/or limited information, but may also be made in a virtual setting. Decision makers may not be engaged in face-to-face deliberations. Hence, understanding the challenges, complexity, and rewards of the use of technology, especially information technology in managerial decision-making, is important. Such an understanding is not only vital in determining the efficacy of managers and their organizations, but also significant in designing future management approaches and organizations. This is the core objective of this chapter.

A Model for Teacher Training to Improve Students' 21st Century Skills in Online and Blended Learning

2018 ◽  
pp. 399-427
Author(s):  
Julia Breddermann ◽  
Juan-Francisco Martínez-Cerdá ◽  
Joan Torrent-Sellens
Keyword(s):  
Teacher Training ◽  
21St Century ◽  
21St Century Skills ◽  
Educational Environment ◽  
Face To Face ◽  
Knowledge Based ◽  
Professional Challenges ◽  
Film Education ◽  
Social Innovations ◽  
K 12

This chapter presents and develops a model of teacher training considering six socio-technical areas that are currently affecting the K-12 educational environment in both face-to-face, blended and online learning: 1) development of 21st century skills; 2) conducting social innovations; 3) appropriate knowledge management among educators; 4) a renovation of classrooms in pursuit of creative classrooms; 5) effective educational practices; and 6) all these issues under a formal educational context that has its own standard and curricular rules. In this context, a literature review on skills needed in the knowledge based society has been realized together with an analysis of possible film education scenarios for media and web-enhanced classrooms, and an exploratory qualitative research about actual ICT activities at school and their outcomes. The entire research regards teachers' lifelong learning with the aim to acquire regularly new competencies. These new abilities enable them to face new professional challenges.

Instructional Design for Millennials

2016 ◽  
pp. 1980-2004
Author(s):  
William Loose ◽  
Teri Marcos
Keyword(s):  
Higher Education ◽  
Instructional Design ◽  
State Standards ◽  
Institutions Of Higher Education ◽  
Course Content ◽  
Face To Face ◽  
Changing Practice ◽  
New Knowledge ◽  
K 12 ◽  
Delivery Models

The authors have worked since 2000 to prepare school leaders at two California Institutions of Higher Education (IHE) in partnership with K-12 public, private, and charter schools. While transforming their programs into virtual delivery models, as an option for students, both online and face-to-face hybrid formats require conditions that help students effectively succeed as learners. Over fifteen years the authors have narrowed discussions for efficient facilitation and mapping to course content while personalizing lessons to deeply engage their learners' creation of new knowledge. They make twenty-three recommendations for streamlining course content, assignments, and assessments to meet individual needs of students while meeting the expectations and challenges of changing national and state standards. The authors conclude that ‘thinking anew' through faculty ideation is a must for IHEs as the changing learner demands changing practice.

And in the End …

2021 ◽  
pp. 217-224
Author(s):  
Jonathan Reades ◽  
Martin Crookston
Keyword(s):  
Strength Test ◽  
Urban Experience ◽  
Central Places ◽  
Face To Face ◽  
The Core ◽  
Full Strength ◽  
Human Contact ◽  
Long Run ◽  
Work World ◽  
Being There

We draw together the book’s themes. These revolve round the core importance of human contact, with face-to-face ever more important, not less, because when insight and knowledge matter F2F will always have the edge. This is despite the ever-deeper penetration of ICT, which allows more choice, accelerates change and enables unparalleled contact, but doesn’t replace face-to face. The pandemic ran a full-strength test of what an e-only work world could be like. The experience will cement and accelerate certain tendencies that already existed, but will not create fundamentally new ones. The long-run strength of central places is because ‘cities are about uncertainty’ and their offer of proximity, of the ‘buzz’, and of confidence is vital. The potential is great: ‘being there’ is still at the core of the urban experience, and face-to-face contact is what towns and cities do for a living.

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