scholarly journals Characterization of Two Mitochondrial Flavin Adenine Dinucleotide-Dependent Glycerol-3-Phosphate Dehydrogenases in Trypanosoma brucei

2013 ◽  
Vol 12 (12) ◽  
pp. 1664-1673 ◽  
Author(s):  
Ingrid Škodová ◽  
Zdeněk Verner ◽  
Fréderic Bringaud ◽  
Peter Fabian ◽  
Julius Lukeš ◽  
...  
Keyword(s):  
Rna Interference ◽  
Trypanosoma Brucei ◽  
Flavin Adenine Dinucleotide ◽  
The Other ◽  
Dihydroxyacetone Phosphate ◽  
Protein Overexpression ◽  
Content Type ◽  
Digitonin Permeabilization ◽  
Shed Light

ABSTRACT Glycerol-3-phosphate dehydrogenases (G3PDHs) constitute a shuttle that serves for regeneration of NAD + reduced during glycolysis. This NAD-dependent enzyme is employed in glycolysis and produces glycerol-3-phosphate from dihydroxyacetone phosphate, while its flavin adenine dinucleotide (FAD)-dependent homologue catalyzes a reverse reaction coupled to the respiratory chain. Trypanosoma brucei possesses two FAD-dependent G3PDHs. While one of them (mitochondrial G3PDH [mtG3PDH]) has been attributed to the mitochondrion and seems to be directly involved in G3PDH shuttle reactions, the function of the other enzyme (putative G3PDH [putG3PDH]) remains unknown. In this work, we used RNA interference and protein overexpression and tagging to shed light on the relative contributions of both FAD-G3PDHs to overall cellular metabolism. Our results indicate that mtG3PDH is essential for the bloodstream stage of T. brucei , while in the procyclic stage the enzyme is dispensable. Expressed putG3PDH-V5 was localized to the mitochondrion, and the data obtained by digitonin permeabilization, Western blot analysis, and immunofluorescence indicate that putG3PDH is located within the mitochondrion.

scholarly journals In Trypanosoma brucei RNA Editing, TbMP18 (Band VII) Is Critical for Editosome Integrity and for both Insertional and Deletional Cleavages

2006 ◽  
Vol 27 (2) ◽  
pp. 777-787 ◽  
Author(s):  
Julie A. Law ◽  
Sean O'Hearn ◽  
Barbara Sollner-Webb
Keyword(s):  
Rna Interference ◽  
Trypanosoma Brucei ◽  
Rna Editing ◽  
Protein Complex ◽  
Substrate Recognition ◽  
The Other ◽  
Major Protein

ABSTRACT In trypanosome RNA editing, uridylate (U) residues are inserted and deleted at numerous sites within mitochondrial pre-mRNAs by an ∼20S protein complex that catalyzes cycles of cleavage, U addition/U removal, and ligation. We used RNA interference to deplete TbMP18 (band VII), the last unexamined major protein of our purified editing complex, showing it is essential. TbMP18 is critical for the U-deletional and U-insertional cleavages and for integrity of the ∼20S editing complex, whose other major components, TbMP99, TbMP81, TbMP63, TbMP52, TbMP48, TbMP42 (bands I through VI), and TbMP57, instead sediment as ∼10S associations. Additionally, TbMP18 augments editing substrate recognition by the TbMP57 terminal U transferase, possibly aiding the recognition component, TbMP81. The other editing activities and their coordination in precleaved editing remain active in the absence of TbMP18. These data are reminiscent of the data on editing subcomplexes reported by A. Schnaufer et al. (Mol. Cell 12:307-319, 2003) and suggest that these subcomplexes are held together in the ∼20S complex by TbMP18, as was proposed previously. Our data additionally imply that the proteins are less long-lived in these subcomplexes than they are when held in the complete editing complex. The editing endonucleolytic cleavages being lost when the editing complex becomes fragmented, as upon TbMP18 depletion, should be advantageous to the trypanosome, minimizing broken mRNAs.

Harris, Chomsky and the origins of transformational grammar

2016 ◽  
Vol 39 (1) ◽  
pp. 48-87
Author(s):  
Giorgio Graffi
Keyword(s):  
Present Article ◽  
The Other ◽  
Auxiliary System ◽  
Transformational Grammar ◽  
Content Type ◽  
The One ◽  
Working Out ◽  
Shed Light

According to Chomsky’s report of the mid 1970s, he and Harris developed their theories in an essentially independent way; whereas according to some statements by Harris, some contact actually took place between them. To shed light on this issue, it may be useful to systematically compare their respective views of the notion ‘transformation’ as well as their analyses of certain syntactic phenomena. Among the topics dealt with in the present article are: the system of syntactic categories and their symbols; the notion of ‘zero elements’; the phenomenon of discontinuous constituents; the English auxiliary system; wh-constructions; the typology of transformations; the notions of ‘kernel’ and ‘kernel sentence’. Several of these analyses show many points of contact between the two scholars (e.g., the analysis of wh-constructions or that of English auxiliaries), which allow us to maintain that they surely influenced each other. The overall differences between the two models are also clear: the transformational relation holds between sentences in Harris’s framework, while it holds between underlying strings on the one hand and actual sentences on the other in Chomsky’s. As a consequence of this different view of the notion of transformation, two problems which were fundamental for Chomsky had no importance for Harris, namely the order of transformations and the distinction between optional and obligatory transformations. It can therefore be concluded that, if the two scholars certainly influenced each other when they were working out their respective transformational theories, their theoretical views were acutely different almost from the beginning.

Design and characterization of a T-shaped two-axis force sensor

Sensor Review ◽  
2019 ◽  
Vol 39 (6) ◽  
pp. 776-782
Author(s):  
Liang Zhong ◽  
Feifei Li ◽  
Yuxin Peng ◽  
Qiang Yang ◽  
Mingming Zhang ◽  
...  
Keyword(s):  
Design Methodology ◽  
Simple Structure ◽  
Force Sensor ◽  
The Other ◽  
Strain Gauges ◽  
Content Type ◽  
Sensor Head ◽  
Compact Size ◽  
Basic Performance

Purpose This paper aims to propose a type of T-shaped two-axis force sensor for measuring the forces in x- and z-axes. The developed sensor has a simple structure and can be effectively assembled into compact devices. Design/methodology/approach A T-shaped plate, with both ends fixed on a base, is used as the substrate of the sensor. Eight strain gauges are placed in the root of the plate or near the sensor head, which can construct two full Wheatstone bridges on the upper and lower surfaces of the plate. When the x- or z-axes forces are applied to the sensor head, different deformation can be generated to the strain gauges. Therefore, the two Wheatstone bridges can be constructed with a different configuration for measuring the forces in x- or z-axes, respectively. Findings A prototype was designed and constructed and experiments were carried out to test the basic performance of the sensor. It has been verified that the developed sensor could measure the x- and z-axes forces independently with a high resolution of 2.5 and 5 mN, respectively. Originality/value Only one thin plate was used in the design, the forces in x- and z-axes could be measured independently and simultaneously, which made the sensor with a simple structure and compact size. Experiments were also verified that there was no crosstalk error occurred in one axis when the force was applied to the other axis.

scholarly journals A New Strategy of RNA Interference That Targets Heterologous Sequences Reveals CITFA1 as an Essential Component of Class I Transcription Factor A in Trypanosoma brucei

2014 ◽  
Vol 13 (6) ◽  
pp. 785-795 ◽  
Author(s):  
Sung Hee Park ◽  
Bao N. Nguyen ◽  
Justin K. Kirkham ◽  
Tu N. Nguyen ◽  
Arthur Günzl
Keyword(s):  
Transcription Factor ◽  
Rna Interference ◽  
Rna Polymerase ◽  
Trypanosoma Brucei ◽  
Transcription Initiation ◽  
Single Copy ◽  
Rna Polymerase I ◽  
Class I ◽  
Content Type ◽  
Polymerase I

ABSTRACTConditional gene silencing by RNA interference inTrypanosoma bruceican be inconclusive if knockdowns are inefficient or have off-target effects. To enable efficient, specific silencing of single-copy genes in mammalian-infective, bloodstream form trypanosomes, we developed a system that targets the heterologous and functionalTrypanosoma cruziU2AF353′ untranslated region (UTR) (Tc3) or, alternatively, the sequence of the PTP tag, which can be fused to any mRNA of interest. Two cell lines were created, single-marker Tc3 (smTc3) and smPTP, which conditionally express Tc3 and PTP double-stranded RNA (dsRNA), respectively. The system depends on manipulating both alleles of the gene of interest so that cells exclusively express the target mRNA as a fusion to one of these heterologous sequences. We generated allele integration vectors in which the C-terminal part of a gene's coding sequence can be fused to either heterologous sequence in a single cloning step. We first tested this system withCITFA7, which encodes a well-characterized subunit of the class I transcription factor A (CITFA), an essential factor for transcription initiation by RNA polymerase I. Targeting either Tc3 or PTP fused to theCITFA7mRNA resulted in gene knockdowns that were as efficient and specific as targeting the endogenousCITFA7mRNA. Moreover, application of this system toCITFA1, which could not be silenced by established methods, demonstrated that the gene encodes an essential CITFA subunit that mediates binding of the transcription factor complex to RNA polymerase I promoters.

scholarly journals The Ancient Small GTPase Rab21 Functions in Intermediate Endocytic Steps in Trypanosomes

2013 ◽  
Vol 13 (2) ◽  
pp. 304-319 ◽  
Author(s):  
Moazzam Ali ◽  
Ka Fai Leung ◽  
Mark C. Field
Keyword(s):  
Rna Interference ◽  
Trypanosoma Brucei ◽  
Cellular Proliferation ◽  
Small Gtpase ◽  
Eukaryotic Cells ◽  
Content Type ◽  
Endosomal Sorting ◽  
Intimate Connection ◽  
Late Endosomes ◽  
Higher Eukaryotes

ABSTRACTEndocytosis is an essential process in nearly all eukaryotic cells, including the African trypanosomeTrypanosoma brucei. Endocytosis in these organisms is exclusively clathrin mediated, although several lineage-specific features indicate that precise mechanisms are distinct from those of higher eukaryotes.T. bruceiRab21 is a member of an ancient, pan-eukaryotic, endocytic Rab clade that is retained by trypanosomes. We show thatT. bruceiRab21 (TbRab21) localizes to endosomes, partially colocalizing with TbRab5A, TbRab28, and TbVps23, the latter two being present at late endosomes. TbRab21 expression is essential for cellular proliferation, and its suppression results in a partial block in traffic to the lysosome. RNA interference (RNAi)-mediated knockdown of TbRab21 had no effect on TbRab5A expression or location but did result in decreased intransexpression of ESCRT (trypanosome endosomal sorting complex required for transport) components and TbRab28, while knockdown of ESCRT subunit TbVps23 resulted in decreased TbRab21 expression. These data suggest that TbRab21 acts downstream of TbRab5A and functions in intimate connection with the trypanosome ESCRT system.

scholarly journals Biochemical Characterization of the Drosophila Wingless Signaling Pathway Based on RNA Interference

2004 ◽  
Vol 24 (5) ◽  
pp. 2012-2024 ◽  
Author(s):  
Hiroko Matsubayashi ◽  
Sonoka Sese ◽  
Jong-Seo Lee ◽  
Tadaoki Shirakawa ◽  
Takeshi Iwatsubo ◽  
...  
Keyword(s):  
Rna Interference ◽  
Biochemical Characterization ◽  
The Other ◽  
Protein Levels ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Mediated Priming ◽  
Kinase A

ABSTRACT Regulation of Armadillo (Arm) protein levels through ubiquitin-mediated degradation plays a central role in the Wingless (Wg) signaling. Although zeste-white3 (Zw3)-mediated Arm phosphorylation has been implicated in its degradation, we have recently shown that casein kinase Iα (CKIα) also phosphorylates Arm and induces its degradation. However, it remains unclear how CKIα and Zw3, as well as other components of the Arm degradation complex, regulate Arm phosphorylation in response to Wg. In particular, whether Wg signaling suppresses CKIα- or Zw3-mediated Arm phosphorylaytion in vivo is unknown. To clarify these issues, we performed a series of RNA interference (RNAi)-based analyses in Drosophila S2R+ cells by using antibodies that specifically recognize Arm phosphorylated at different serine residues. These analyses revealed that Arm phosphorylation at serine-56 and at threonine-52, serine-48, and serine-44, is mediated by CKIα and Zw3, respectively, and that Zw3-directed Arm phosphorylation requires CKIα-mediated priming phosphorylation. Daxin stimulates Zw3- but not CKIα-mediated Arm phosphorylation. Wg suppresses Zw3- but not CKIα-mediated Arm phosphorylation, indicating that a vital regulatory step in Wg signaling is Zw3-mediated Arm phosphorylation. In addition, further RNAi-based analyses of the other aspects of the Wg pathway clarified that Wg-induced Dishevelled phosphoylation is due to CKIα and that presenilin and protein kinase A play little part in the regulation of Arm protein levels in Drosophila tissue culture cells.

scholarly journals An Unpublished Manuscript of The Teaching of Khety (P. Turin CGT 54019)

2021 ◽  
Vol 5 ◽  
Author(s):  
Judith Jurjens
Keyword(s):  
The Other ◽  
Literary Texts ◽  
Arabic Text ◽  
Additional Source ◽  
Unpublished Manuscript ◽  
Content Type ◽  
The Social ◽  
Medinet Habu ◽  
The Relationship ◽  
Shed Light

This paper is a publication of P. Turin CGT 54019, which contains an excerpt from The Teaching of Khety, also known as The Satire of the Trades. The papyrus provides a welcome additional source for the second part of the composition (chapters 21–30), particularly because it offers some interesting variants that are unparalleled in the other sources. After a brief introduction on variants in general, including scribal errors, these variants are discussed in detail. The colophon that concludes the papyrus is badly preserved. However, it mentions the mortuary temple of Ramesses III at Medinet Habu. This is quite remarkable, since locations are seldom referred to in the colophons of literary texts. These rare instances are analyzed here to try to reconstruct the manuscript’s colophon. Finally, the relationship between literary texts and mortuary temples is discussed to shed light on the social context of P. Turin CGT 54019. ملخص هذا النص هو إحدى منشورات P. Turin CGT 54019، والذي يحتوي على مقتطف من "وصايا خيتي" ، المعروف أيضاً باسم "مساوئ الحِرَف". تمثل البردية مصدراً إضافياً لمقدمة الجزء الثاني من العمل (الفصول 21-30)، وبالتحديد لأنها تقدم بعض المتغيرات المثيرة للاهتمام التي لا مثيل لها في المصادر الأخرى. بعد مقدمة موجزة عن المتغيرات بشكل عام، بما في ذلك أخطاء الكاتب، تمّت مناقشة هذه المتغيرات بالتفصيل. بيانات المنشور التي تختم بها البردية محفوظة بشكل سيئ. ومع ذلك فإنها تتحدث عن المعبد الجنائزي لرمسيس الثالث في مدينة هابو. هذا أمر جدير بالذكر، حيث نادراً ما يشار إلى موقع محدد في بيانات المنشور للنصوص الأدبية. يتم هنا دراسة وتحليل هذه الحالات النادرة لمحاولة إعادة بناء بيانات المنشور الخاصة بالمخطوطة. أخيراً، تمت مناقشة العلاقة بين النصوص الأدبية والمعابد الجنائزية لإلقاء الضوء على المنظومة الاجتماعية لـ P. Turin CGT 54019 .

scholarly journals A theoretical framework to identify authentic online reviews

2014 ◽  
Vol 38 (5) ◽  
pp. 634-649 ◽  
Author(s):  
Snehasish Banerjee ◽  
Alton Y.K. Chua
Keyword(s):  
Design Methodology ◽  
Online Reviews ◽  
Theoretical Framework ◽  
Research Area ◽  
The Other ◽  
Data Sets ◽  
Writing Style ◽  
Content Type ◽  
Negative Comments ◽  
Shed Light

Purpose – The purpose of this paper is to investigate the extent to which textual characteristics of online reviews help identify authentic entries from manipulative ones across positive and negative comments. Design/methodology/approach – A theoretical framework is proposed to identify authentic online reviews from manipulative ones based on three textual characteristics, namely, comprehensibility, informativeness, and writing style. The framework is tested using two publicly available data sets, one comprising positive reviews to hype own offerings, and the other including negative reviews to slander competing offerings. Logistic regression is used for analysis. Findings – The three textual characteristics offered useful insights to identify authentic online reviews from manipulative ones. In particular, the differences between authentic and manipulative reviews in terms of comprehensibility and informativeness were more conspicuous for negative entries. On the other hand, the differences between authentic and manipulative reviews in terms of writing style were more conspicuous for positive entries. Research limitations/implications – The findings of this paper are somewhat constrained by the scope of the data sets used for analysis. Originality/value – The paper represents one of the earliest attempts to develop a theoretical framework to identify authentic online reviews. Prior research has shed light on ways to classify reviews as authentic or manipulative. However, literature on specific differences between the two in terms of textual characteristics is relatively limited. Moreover, by suggesting differences between authentic and manipulative reviews across positive and negative comments, the findings offer nuanced insights into a research area that is growing in importance.

Mustapha and Greville

2017 ◽  
pp. 145-158
Author(s):  
Önder Çakırtaş
Keyword(s):  
Point Of View ◽  
The Other ◽  
Historical Background ◽  
English Renaissance ◽  
Dramatic Works ◽  
Other Hand ◽  
Fulke Greville ◽  
Islamic Politics ◽  
Shed Light

Whilst Jonathan Burton—deactivating or mincing matters with Said's Orientalism—coined the word ‘trafficking' for the repercussions of Eastern/Islamic/Ottomanic characterization of Western authors, Linda McJannet, on the other hand—backing Said's Orientalism—went into Bakhtin's ‘heteroglossia', and stressed the polyphonic representation of dramatic works through the word ‘pragmatic ambivalence', a characterization of English authors toward the Islamic politics. Both Burton and McJannet touched pre-eminently on the Renaissance writers to define their literariness. The present chapter aims to shed light on the historical background and dramatic representation regarding Mustapha's tragic death through majoring Anglo-Ottoman diplomacy and producing a base for Machiavellian point of view. The study is based on a dramatic work of an English Renaissance playwright, Fulke Greville, who adapted Prince Mustapha's death for the stage.

scholarly journals Identification of Loci and Functional Characterization of Trichothecene Biosynthesis Genes in Filamentous Fungi of the Genus Trichoderma

2011 ◽  
Vol 77 (14) ◽  
pp. 4867-4877 ◽  
Author(s):  
R. E. Cardoza ◽  
M. G. Malmierca ◽  
M. R. Hermosa ◽  
N. J. Alexander ◽  
S. P. McCormick ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Gene Rearrangement ◽  
Gene Loss ◽  
Functional Characterization ◽  
The Other ◽  
Regulatory Proteins ◽  
Biosynthetic Gene ◽  
Content Type ◽  
Cluster Organization

ABSTRACTTrichothecenes are mycotoxins produced byTrichoderma,Fusarium, and at least four other genera in the fungal orderHypocreales.Fusariumhas a trichothecene biosynthetic gene (TRI) cluster that encodes transport and regulatory proteins as well as most enzymes required for the formation of the mycotoxins. However, little is known about trichothecene biosynthesis in the other genera. Here, we identify and characterizeTRIgene orthologues (tri) inTrichoderma arundinaceumandTrichoderma brevicompactum. Our results indicate that bothTrichodermaspecies have atricluster that consists of orthologues of seven genes present in theFusariumTRIcluster. Organization of genes in the cluster is the same in the twoTrichodermaspecies but differs from the organization inFusarium. Sequence and functional analysis revealed that the gene (tri5) responsible for the first committed step in trichothecene biosynthesis is located outside the cluster in bothTrichodermaspecies rather than inside the cluster as it is inFusarium. Heterologous expression analysis revealed that twoT. arundinaceumcluster genes (tri4andtri11) differ in function from theirFusariumorthologues. TheTatri4-encoded enzyme catalyzes only three of the four oxygenation reactions catalyzed by the orthologous enzyme inFusarium. TheTatri11-encoded enzyme catalyzes a completely different reaction (trichothecene C-4 hydroxylation) than theFusariumorthologue (trichothecene C-15 hydroxylation). The results of this study indicate that although some characteristics of thetri/TRIcluster have been conserved during evolution ofTrichodermaandFusarium, the cluster has undergone marked changes, including gene loss and/or gain, gene rearrangement, and divergence of gene function.

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