scholarly journals Transcription-termination-mediated immunity and its prevention in bacteriophage SfV of Shigella flexneri

2007 ◽  
Vol 88 (11) ◽  
pp. 3187-3197 ◽  
Author(s):  
Fleur Roberts ◽  
Gwen E. Allison ◽  
Naresh K. Verma
Keyword(s):  
Essential Role ◽  
Transcription Termination ◽  
Shigella Flexneri ◽  
Temperate Phage ◽  
The Novel ◽  
Subsequent Infection

The temperate phage SfV encodes the genes responsible for the serotype conversion of Shigella flexneri strains from serotype Y to 5a. Bacteriophages often encode proteins that prevent subsequent infection by homologous phages; the mechanism by which this is accomplished is referred to as superinfection immunity. The serotype conversion mediated following lysogenization of SfV is one such mechanism. Another mechanism is the putative λ-like CI protein within SfV. This study reports the characterization of a third superinfection mechanism, transcription termination, in SfV. The presence of a small immunity-mediating RNA molecule, called CI RNA, and its essential role in the establishment of immunity, is shown. The novel role of the gene orf77, located immediately downstream from the transcription termination region, in inhibiting the establishment of CI RNA-mediated immunity is also presented.

Le premier moment de l’art dans À la recherche du temps perdu de Marcel Proust – une « leçon d’idéalisme » ?

2020 ◽  
pp. 25-40
Author(s):  
Larisa Botnari
Keyword(s):  
Essential Role ◽  
Marcel Proust ◽  
The Self ◽  
Philosophy Of Art ◽  
The Novel ◽  
Philosophical Interpretation ◽  
German Philosopher ◽  
Lost Time ◽  
Aesthetic Thinking

Although very famous, some key moments of the novel In Search of Lost Time, such as those of the madeleine or the uneven pavement, often remain enigmatic for the reader. Our article attempts to formulate a possible philosophical interpretation of the narrator's experiences during these scenes, through a confrontation of the Proustian text with the ideas found in the System of Transcendental Idealism (1800) of the German philosopher F. W. J. Schelling. We thus try to highlight the essential role of the self in Marcel Proust's aesthetic thinking, by showing that the mysterious happiness felt by the narrator, and from which the project of creating a work of art is ultimately born, is similar to the experiences of pure self-consciousness evoked and analyzed by Schellingian philosophy of art.

scholarly journals RNA polymerase II plays an active role in the formation of gene loops through the Rpb4 subunit

2019 ◽  
Vol 47 (17) ◽  
pp. 8975-8987 ◽  
Author(s):  
Paula Allepuz-Fuster ◽  
Michael J O’Brien ◽  
Noelia González-Polo ◽  
Bianca Pereira ◽  
Zuzer Dhoondia ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Essential Role ◽  
Transcription Termination ◽  
Active Role ◽  
The Other ◽  
Loop Formation ◽  
Direct Role

AbstractGene loops are formed by the interaction of initiation and termination factors occupying the distal ends of a gene during transcription. RNAPII is believed to affect gene looping indirectly owing to its essential role in transcription. The results presented here, however, demonstrate a direct role of RNAPII in gene looping through the Rpb4 subunit. 3C analysis revealed that gene looping is abolished in the rpb4Δ mutant. In contrast to the other looping-defective mutants, rpb4Δ cells do not exhibit a transcription termination defect. RPB4 overexpression, however, rescued the transcription termination and gene looping defect of sua7-1, a mutant of TFIIB. Furthermore, RPB4 overexpression rescued the ssu72-2 gene looping defect, while SSU72 overexpression restored the formation of gene loops in rpb4Δ cells. Interestingly, the interaction of TFIIB with Ssu72 is compromised in rpb4Δ cells. These results suggest that the TFIIB–Ssu72 interaction, which is critical for gene loop formation, is facilitated by Rpb4. We propose that Rpb4 is promoting the transfer of RNAPII from the terminator to the promoter for reinitiation of transcription through TFIIB–Ssu72 mediated gene looping.

Characterization of Marine Temperate Phage-Host Systems Isolated from Mamala Bay, Oahu, Hawaii

1998 ◽  
Vol 64 (2) ◽  
pp. 535-542 ◽  
Author(s):  
Sunny C. Jiang ◽  
Christina A. Kellogg ◽  
John H. Paul
Keyword(s):  
Water Samples ◽  
Blot Hybridization ◽  
Temperate Phage ◽  
Dot Blot ◽  
Dot Blot Hybridization ◽  
Double Stranded Dna ◽  
The Family ◽  
Marine Viruses

ABSTRACT To understand the ecological and genetic role of viruses in the marine environment, it is critical to know the infectivity of viruses and the types of interactions that occur between marine viruses and their hosts. We isolated four marine phages from turbid plaques by using four indigenous bacterial hosts obtained from concentrated water samples from Mamala Bay, Oahu, Hawaii. Two of the rod-shaped bacterial hosts were identified as Sphingomonas paucimobilis andFlavobacterium sp. All of the phage isolates were tailed phages and contained double-stranded DNA. Two of the phage isolates had morphologies typical of the family Siphoviridae, while the other two belonged to the families Myoviridae andPodoviridae. The head diameters of these viruses ranged from 47 to 70.7 nm, and the tail lengths ranged from 12 to 146 nm. The burst sizes ranged from 7.8 to 240 phage/bacterial cell, and the genome sizes, as determined by restriction digestion, ranged from 36 to 112 kb. The members of the Siphoviridae, T-φHSIC, and T-φD0, and the member of the Myoviridae, T-φD1B, were found to form lysogenic associations with their bacterial hosts, which were isolated from the same water samples. Hybridization of phage T-φHSIC probe with lysogenic host genomic DNA was observed in dot blot hybridization experiments, indicating that prophage T-φHSIC was integrated within the host genome. These phage-host systems are available for use in studies of marine lysogeny and transduction.

scholarly journals Essential Role of the Oocyte in Estrogen Amplification of Follicle-Stimulating Hormone Signaling in Granulosa Cells

Endocrinology ◽  
2005 ◽  
Vol 146 (8) ◽  
pp. 3362-3367 ◽  
Author(s):  
Fumio Otsuka ◽  
R. Kelly Moore ◽  
Xia Wang ◽  
Shweta Sharma ◽  
Tomoko Miyoshi ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Granulosa Cells ◽  
Essential Role ◽  
Primary Cultures ◽  
The Novel ◽  
Camp Production ◽  
Lh Receptor ◽  
Cell Responses ◽  
A Site

Abstract The establishment of dominant ovarian follicles that are capable of ovulating fertilizable oocytes is a fundamental determinant of female fertility. This process is governed by pituitary gonadotropins as well as local ovarian factors. Within the follicle, estrogen acts in an autocrine/paracrine manner to enhance FSH action in the granulosa cells. These effects include the augmentation of P450aromatase expression and estradiol production. This feed-forward effect of estrogen is believed to play a key role in follicle dominance. Here we found the essential role of the oocyte in this physiological process using primary cultures of rat granulosa cells. In the presence, but not absence, of oocytes, estrogen amplified FSH-stimulated increases in mRNA expression of P450aromatase, FSH receptor, LH receptor, and inhibin α-, βA-, and βB-subunits as well as cAMP production. Thus, oocytes mediate the estrogen enhancement of FSH action in the granulosa cells. In comparison with FSH, cotreatment with estrogen and oocytes failed to amplify the stimulatory effects of forskolin or 8-bromoadenosine-cAMP on granulosa cell responses including P450aromatase mRNA expression and cAMP production, indicating that estrogen/oocytes amplify FSH action at a site upstream of adenylate cyclase. These findings support the novel conclusion that communication between the oocyte and granulosa cells plays a crucial role in mediating estrogen action during FSH-dependent folliculogenesis.

scholarly journals Development and Characterization of Anti-Nitr9 Antibodies

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Radhika N. Shah ◽  
Ivan Rodriguez-Nunez ◽  
Donna D. Eason ◽  
Robert N. Haire ◽  
Julien Y. Bertrand ◽  
...  
Keyword(s):  
Rna Splicing ◽  
Killer Cell ◽  
The Novel ◽  
Natural Killer Cell Receptors ◽  
Hematopoietic Lineage ◽  
Activating Receptors ◽  
Functional Orthologs ◽  
Activating Receptor

The novel immune-type receptors (NITRs), which have been described in numerous bony fish species, are encoded by multigene families of inhibitory and activating receptors and are predicted to be functional orthologs to the mammalian natural killer cell receptors (NKRs). Within the zebrafish NITR family,nitr9is the only gene predicted to encode an activating receptor. However, alternative RNA splicing generates three distinctnitr9transcripts, each of which encodes a different isoform. Althoughnitr9transcripts have been detected in zebrafish lymphocytes, the specific hematopoietic lineage(s) that expresses Nitr9 remains to be determined. In an effort to better understand the role of NITRs in zebrafish immunity, anti-Nitr9 monoclonal antibodies were generated and evaluated for the ability to recognize the three Nitr9 isoforms. The application of these antibodies to flow cytometry should prove to be useful for identifying the specific lymphocyte lineages that express Nitr9 and may permit the isolation of Nitr9-expressing cells that can be directly assessed for cytotoxic (e.g., NK) function.

scholarly journals Isolation and characterization of a novel bacteriophage, Kapi1, capable of O-antigen modification in commensal Escherichia coli.

2021 ◽  
Author(s):  
Kat Pick ◽  
Tracy Lyn Raivio
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Shigella Flexneri ◽  
Model System ◽  
Temperate Phage ◽  
Phage Displays ◽  
E Coli ◽  
O Antigen ◽  
Isolation And Characterization

In this study, we describe the isolation and characterization of novel bacteriophage Kapi1 (vB_EcoP_Kapi1) isolated from a strain of commensal Escherichia coli inhabiting the gastrointestinal tract of healthy mice. We show that Kapi1 is a temperate phage integrated into tRNA argW of strain MP1 and describe its genome annotation and structure. Kapi1 shows limited homology to other characterized prophages but is most similar to the phages of Shigella flexneri, and clusters taxonomically with P22-like phages. Investigation of the lifestyle of Kapi1 shows that this phage displays unstable lysogeny and influences the growth of its host. The receptor for Kapi1 is the lipopolysaccharide O-antigen, and we further show that Kapi1 alters the structure of its hosts O-antigen in multiple ways. We hope to use MP1 and Kapi1 as a model system to explore molecular mechanisms of mammalian colonization by E. coli and ask what the role(s) of prophages in this context might be.

The perception of quantity ain't number: Missing the primacy of symbolic reference

2021 ◽  
Vol 44 ◽  
Author(s):  
Rafael E. Núñez ◽  
Francesco d'Errico ◽  
Russell D. Gray ◽  
Andrea Bender
Keyword(s):  
Essential Role ◽  
Number System ◽  
Rational Numbers ◽  
Theoretical Construct ◽  
Approximate Number System

Abstract Clarke and Beck's defense of the theoretical construct “approximate number system” (ANS) is flawed in serious ways – from biological misconceptions to mathematical naïveté. The authors misunderstand behavioral/psychological technical concepts, such as numerosity and quantical cognition, which they disdain as “exotic.” Additionally, their characterization of rational numbers is blind to the essential role of symbolic reference in the emergence of number.

Purification and characterization of Caenorhabditis elegans NTH, a homolog of human endonuclease III: Essential role of N-terminal region

DNA Repair ◽  
2009 ◽  
Vol 8 (7) ◽  
pp. 844-851 ◽  
Author(s):  
Hironobu Morinaga ◽  
Shin-Ichiro Yonekura ◽  
Nobuya Nakamura ◽  
Hiroshi Sugiyama ◽  
Shuji Yonei ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Essential Role ◽  
Terminal Region ◽  
Purification And Characterization ◽  
Endonuclease Iii
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