scholarly journals Regulation of INF2-mediated actin polymerization through site-specific lysine acetylation of actin itself

2019 ◽  
Vol 117 (1) ◽  
pp. 439-447 ◽  
Author(s):  
Mu A ◽  
Tak Shun Fung ◽  
Lisa M. Francomacaro ◽  
Thao Huynh ◽  
Tommi Kotila ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Full Length ◽  
Common Mechanism ◽  
Binding Studies ◽  
Direct Binding ◽  
Wh2 Domain ◽  
Inhibitory Domain ◽  
Low Levels ◽  
U2os Cells ◽  
Better Than

INF2 is a formin protein that accelerates actin polymerization. A common mechanism for formin regulation is autoinhibition, through interaction between the N-terminal diaphanous inhibitory domain (DID) and C-terminal diaphanous autoregulatory domain (DAD). We recently showed that INF2 uses a variant of this mechanism that we term “facilitated autoinhibition,” whereby a complex consisting of cyclase-associated protein (CAP) bound to lysine-acetylated actin (KAc-actin) is required for INF2 inhibition, in a manner requiring INF2-DID. Deacetylation of actin in the CAP/KAc-actin complex activates INF2. Here we use lysine-to-glutamine mutations as acetylmimetics to map the relevant lysines on actin for INF2 regulation, focusing on K50, K61, and K328. Biochemically, K50Q- and K61Q-actin, when bound to CAP2, inhibit full-length INF2 but not INF2 lacking DID. When not bound to CAP, these mutant actins polymerize similarly to WT-actin in the presence or absence of INF2, suggesting that the effect of the mutation is directly on INF2 regulation. In U2OS cells, K50Q- and K61Q-actin inhibit INF2-mediated actin polymerization when expressed at low levels. Direct-binding studies show that the CAP WH2 domain binds INF2-DID with submicromolar affinity but has weak affinity for actin monomers, while INF2-DAD binds CAP/K50Q-actin 5-fold better than CAP/WT-actin. Actin in complex with full-length CAP2 is predominately ATP-bound. These interactions suggest an inhibition model whereby CAP/KAc-actin serves as a bridge between INF2 DID and DAD. In U2OS cells, INF2 is 90-fold and 5-fold less abundant than CAP1 and CAP2, respectively, suggesting that there is sufficient CAP for full INF2 inhibition.

EFFECTS OF LANGUAGE AND PRIOR KNOWLEDGE LEVELS ON HYPERTEXT READING COMPREHENSION

2020 ◽  
Author(s):  
Kshema Jose
Keyword(s):  
Reading Comprehension ◽  
Prior Knowledge ◽  
Language Proficiency ◽  
Language Competence ◽  
Additional Information ◽  
Reading Order ◽  
Low Levels ◽  
Online Texts ◽  
Characteristic Features ◽  
Better Than

<p>This study observed how two hypertext features – absence of a linear or author-specified order and availability of multiple reading aids – influence reading comprehension processes of ESL readers. Studies with native or highly proficient users of English, have suggested that readers reading hypertexts comprehend better than readers reading print texts. This was attributed to (i) presence of hyperlinks that provide access to additional information that can potentially help overcome comprehension obstacles and (ii) the absence of an author-imposed reading order that helps readers exercise cognitive flexibility. An aspect that remains largely un-researched is how well readers with low language competence comprehend hypertexts. This research sought to initiate research in the area by exploring the question: Do all ESL readers comprehend a hypertext better than a print text?</p> <p>Keeping in mind the fact that a majority of readers reading online texts in English can be hindered by three types of comprehension deficits – low levels of language proficiency, non-availability of prior knowledge, or both – this study investigated how two characteristic features of hypertext, viz., linking to additional information and non-linearity in presentation of information, affect reading comprehension of ESL readers. </p> <p>Two types of texts that occur in the electronic medium – linear or pre-structured texts and non-linear or self-navigating texts, were used in this study. Based on a comparison of subjects’ comprehension outcomes and free recalls, text factors and reader factors that can influence hypertext reading comprehension of ESL readers are identified. </p> Contradictory to what many researchers believe, results indicate that self-navigating hypertexts might not promote deep comprehension in all ESL readers.

scholarly journals Efficacy and Selectivity of FGF2-Saporin Cytosolically Delivered by PCI in Cells Overexpressing FGFR1

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1476
Author(s):  
Aurora K. Vikan ◽  
Michal Kostas ◽  
Ellen Margrethe Haugsten ◽  
Pål K. Selbo ◽  
Jørgen Wesche
Keyword(s):  
Treatment Options ◽  
Current Treatment ◽  
Fibroblast Growth Factor Receptors ◽  
Ribosome Inactivating Protein ◽  
Cytosolic Delivery ◽  
Low Levels ◽  
U2os Cells ◽  
Targeting Effect ◽  
Target Effects ◽  
In Cells

Fibroblast growth factor receptors (FGFRs) have become an attractive target in cancer research and therapy due to their implication in several cancers. Limitations of current treatment options require a need for additional, more specific and potent strategies to overcome cancers driven by FGFRs. Photochemical internalization (PCI) is a light-controlled method for cytosolic delivery of drugs that are entrapped in endosomes and lysosomes. We here evaluated the efficacy and selectivity of PCI of FGF2-saporin (FGF-SAP) in cells overexpressing FGFR1. FGF-SAP is a conjugate of FGF2 and the highly cytotoxic ribosome-inactivating protein (RIP) saporin, which is used as payload to eliminate cancer cells. Evaluation of the targeting effect of PCI of FGF-SAP was done by comparing the cytotoxic response in osteosarcoma cells with very low levels of FGFR1 (U2OS) to cells overexpressing FGFR1 (U2OS-R1). We demonstrate that PCI greatly enhances cytotoxicity of the drug showing efficient cell killing at pM concentrations of the drug in U2OS-R1 cells. However, U2OS cells were also sensitive to the toxin after PCI. Binding experiments using confocal microscopy and Western blotting techniques indicate that FGF-SAP is taken up by cells through heparan sulfate proteoglycans (HSPGs) in U2OS cells. We further show that the cytotoxicity of FGF-SAP in U2OS cells was reduced when cells were co-treated with heparin to compete out binding to HSPG, demonstrating that the cytotoxic effect was due to internalization by HSPGs. We conclude that to prevent off-target effects of FGF-based toxins, it will be necessary to circumvent binding to HSPGs, for example by mutating the binding site of FGF2 to HSPGs.

Evaluation of Gas-Liquid Chromatography in Assays for Blood Volatiles

1965 ◽  
Vol 11 (11) ◽  
pp. 1023-1035 ◽  
Author(s):  
Alan Mather ◽  
Angel Assimos
Keyword(s):  
Liquid Chromatography ◽  
Alcohol Concentration ◽  
Quantitative Assay ◽  
Gas Liquid Chromatography ◽  
Internal Reference ◽  
Detection And Identification ◽  
Large Populations ◽  
The Common ◽  
Low Levels ◽  
Better Than

Abstract A simple screening by gas-liquid chromatography (GLC) can provide definitive answers in the detection and identification of a number of volatile substances, including acetone and the common alcohols. After identification, quantitative assay by an internal-reference technic yields highly specific values for ethyl alcohol concentration with a precision at least equal to (and for low levels, better than) that of conventional assays. The unique advantage of GLC is in its simultaneous quantitative assay of mixtures, some of which cannot be satisfactorily assayed or even recognized in any other way. The combination of speed and negligible sample volumes render the technic valuable for sequential studies on capillary blood samples and, potentially, for mass screening of large populations.

Thermohydraulics of Laminar Flow Through Rectangular and Square Ducts With Transverse Ribs and Twisted Tapes

2006 ◽  
Vol 128 (10) ◽  
pp. 1070-1080 ◽  
Author(s):  
Debashis Pramanik ◽  
Sujoy K. Saha
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Laminar Flows ◽  
Short Length ◽  
Full Length ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Square Ducts ◽  
Better Than

The heat transfer and the pressure drop characteristics of laminar flow of viscous oil through rectangular and square ducts with internal transverse rib turbulators on two opposite surfaces of the ducts and fitted with twisted tapes have been studied experimentally. The tapes have been full length, short length, and regularly spaced types. The transverse ribs in combination with full-length twisted tapes have been found to perform better than either ribs or twisted tapes acting alone. The heat transfer and the pressure drop measurements have been taken in separate test sections. Heat transfer tests were carried out in electrically heated stainless steel ducts incorporating uniform wall heat flux boundary conditions. Pressure drop tests were carried out in acrylic ducts. The flow was periodically fully developed in the regularly spaced twisted-tape elements case and decaying swirl flow in the short-length twisted tapes case. The flow characteristics are governed by twist ratio, space ratio, and length of twisted tape, Reynolds number, Prandtl number, rod-to-tube diameter ratio, duct aspect ratio, rib height, and rib spacing. Correlations developed for friction factor and Nusselt number have predicted the experimental data satisfactorily. The performance of the geometry under investigation has been evaluated. It has been found that on the basis of both constant pumping power and constant heat duty, the regularly spaced twisted-tape elements in specific cases perform marginally better than their full-length counterparts. However, the short-length twisted-tape performance is worse than the full-length twisted tapes. Therefore, full-length twisted tapes and regularly spaced twisted-tape elements in combination with transverse ribs are recommended for laminar flows. However, the short-length twisted tapes are not recommended.

scholarly journals The tandem repeat domain in the Listeria monocytogenes ActA protein controls the rate of actin-based motility, the percentage of moving bacteria, and the localization of vasodilator-stimulated phosphoprotein and profilin.

1996 ◽  
Vol 135 (3) ◽  
pp. 647-660 ◽  
Author(s):  
G A Smith ◽  
J A Theriot ◽  
D A Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Actin Polymerization ◽  
Consensus Sequence ◽  
Wild Type ◽  
Movement Rate ◽  
Bacterial Surface ◽  
Rate Dependent ◽  
Repeat Domain ◽  
Low Levels ◽  
Rate Of Movement

The ActA protein is responsible for the actin-based movement of Listeria monocytogenes in the cytosol of eukaryotic cells. Analysis of mutants in which we varied the number of proline-rich repeats (PRR; consensus sequence DFPPPPTDEEL) revealed a linear relationship between the number of PRRs and the rate of movement, with each repeat contributing approximately 2-3 microns/min. Mutants lacking all functional PRRs (generated by deletion or point mutation) moved at rates 30% of wild-type. Indirect immunofluorescence indicated that the PRRs were directly responsible for binding of vasodilator-stimulated phosphoprotein (VASP) and for the localization of profilin at the bacterial surface. The long repeats, which are interdigitated between the PRRs, increased the frequency with which actin-based motility occurred by a mechanism independent of the PRRs, VASP, and profilin. Lastly, a mutant which expressed low levels of ActA exhibited a phenotype indicative of a threshold; there was a very low percentage of moving bacteria, but when movement did occur, it was at wild-type rates. These results indicate that the ActA protein directs at least three separable events: (1) initiation of actin polymerization that is independent of the repeat region; (2) initiation of movement dependent on the long repeats and the amount of ActA; and (3) movement rate dependent on the PRRs.

scholarly journals Enhancement of mDia2 activity by Rho-kinase-dependent phosphorylation of the diaphanous autoregulatory domain

2011 ◽  
Vol 439 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Dean P. Staus ◽  
Joan M. Taylor ◽  
Christopher P. Mack
Keyword(s):  
Smooth Muscle ◽  
Actin Polymerization ◽  
Serum Response Factor ◽  
Rho Kinase ◽  
Specific Gene ◽  
Related Transcription Factor ◽  
Inhibitory Domain ◽  
Serum Response ◽  
Acidic Region ◽  
Basic Region

It is clear that RhoA activates the DRF (diaphanous-related formin) mDia2 by disrupting the molecular interaction between the DAD (diaphanous autoregulatory domain) and the DID (diaphanous inhibitory domain). Previous studies indicate that a basic motif within the DAD contributes to mDia2 auto-inhibition, and results shown in the present study suggest these residues bind a conserved acidic region within the DID. Furthermore, we demonstrate that mDia2 is phosphorylated by ROCK (Rho-kinase) at two conserved residues (Thr1061 and Ser1070) just C-terminal to the DAD basic region. Phosphomimetic mutations to these residues in the context of the full-length molecule enhanced mDia2 activity as measured by increased actin polymerization, SRF (serum response factor)-dependent smooth muscle-specific gene transcription, and nuclear localization of myocardin-related transcription factor B. Biochemical and functional data indicate that the T1061E/S1070E mutation significantly inhibited the ability of DAD to interact with DID and enhanced mDia2 activation by RhoA. Taken together, the results of the present study indicate that ROCK-dependent phosphorylation of the mDia2 DAD is an important determinant of mDia2 activity and that this signalling mechanism affects actin polymerization and smooth muscle cell-specific gene expression.

The use of hollow sphere pigments as strength additives in paper and paperboard coatings—Part 1: The predictive nature of packing models on coating properties

TAPPI Journal ◽  
2020 ◽  
Vol 19 (11) ◽  
pp. 585-593
Author(s):  
ETHAN GLOR ◽  
BRIAN EINSLA ◽  
JOHN ROPER ◽  
JIAN YANG ◽  
VALERIY GINZBURG
Keyword(s):  
Particle Size ◽  
Hollow Sphere ◽  
Particle Packing ◽  
Particle Sizes ◽  
Coating Properties ◽  
Ideal System ◽  
Thermal Paper ◽  
Effect Of Particle Size ◽  
Low Levels ◽  
Better Than

Hollow sphere pigments (HSPs) are widely used at low levels in coated paper to increase coating bulk and to provide gloss to the final sheet. However, HSPs also provide an ideal system through which one can examine the effect of pigment size and particle packing within a coating due to their unimodal and tunable particle sizes. The work presented in Part 1 and Part 2 of this study will discuss the use of blends of traditional inorganic pigments and HSPs in coating formulations across a variety of applications for improved coating strength. Part 1 of this study focuses on the theory of bimodal spherical packing and demonstrates the predictive nature of packing models on the properties of coating systems containing HSPs of two different sizes. This study also examines conditions where the model fails by examining the effect of particle size on coating strength in sytems like thermal paper basecoats where the non-HSP component has a broad particle size distribution, and how these surprising trends can be used to generate better-than-expected thermal printing performance in systems with low HSP/clay ratios. Part 2 of this study focuses on the incorporation of HSPs of different particle sizes into paperboard formulations to affect coating strength and opacity.

La competencia motriz en estudiantes chilenos de 3° y 4° de educación básica. Aprendizajes esperados versus realidad (Motor competence in Chilean students in 3rd and 4th grade of primary school. Expected learning versus reality)

Retos ◽  
2021 ◽  
Vol 44 ◽  
pp. 515-524
Author(s):  
Daniel Rodríguez-Briceño ◽  
Felipe Castro-Vilugron ◽  
Mauricio Díaz-Alvarado ◽  
Jaime Carcamo Oyarzun
Keyword(s):  
Motor Performance ◽  
Fourth Grade ◽  
Learning Objectives ◽  
Motor Competence ◽  
Object Control ◽  
Third Grade Students ◽  
Fourth Grade Students ◽  
Low Levels ◽  
And Gender ◽  
Better Than

  Este estudio busca determinar los niveles de competencia motriz de estudiantes chilenos y las posibles diferencias en función del grado y del sexo. Participaron 377 estudiantes (37.7% niñas) de tercer y cuarto básico. La competencia motriz fue evaluada a través del test MOBAK 3-4. Se encontraron bajos niveles de competencia motriz. Los estudiantes de cuarto grado presentan un mejor desempeño motriz que los de tercero. Los niños presentan un mayor desempeño que las niñas en control de objetos, mientras que las niñas obtienen puntajes más altos que los niños en control del cuerpo, aunque con un tamaño del efecto irrelevante. Al contrastar estos resultados con los objetivos del currículum, muchos estudiantes no alcanzan los aprendizajes esperados, siendo necesario poner mayor énfasis en el fomento de la competencia motriz.  Abstract. This study aims to determine the levels of motor competence of Chilean students and possible differences according to grade and gender. 377 students (37.7% girls) of the third and fourth grade participated in the study. Motor competence was evaluated through the MOBAK 3-4 test. Low levels of motor competence were found. Fourth grade students showed a better motor performance than third grade students. Boys performed better than girls in object control, while girls scored higher than boys in self-movement, although with an irrelevant effect size. When these results are contrasted with the learning objectives stipulated in the curriculum, many students do not achieve the expected skills, what makes it necessary to place greater emphasis on the promotion of motor competence.

scholarly journals Evaluation of Distributed Collaborative Adaptive Sensing for Detection of Low-Level Circulations and Implications for Severe Weather Warning Operations

2010 ◽  
Vol 25 (1) ◽  
pp. 173-189 ◽  
Author(s):  
J. Brotzge ◽  
K. Hondl ◽  
B. Philips ◽  
L. Lemon ◽  
E. J. Bass ◽  
...  
Keyword(s):  
Severe Weather ◽  
Special Focus ◽  
Test Bed ◽  
Scanning Strategy ◽  
Engineering Research ◽  
Low Level ◽  
Adaptive Sensing ◽  
Low Levels ◽  
Casa System ◽  
Better Than

Abstract The Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is a multiyear engineering research center established by the National Science Foundation for the development of small, inexpensive, low-power radars designed to improve the scanning of the lowest levels (&lt;3 km AGL) of the atmosphere. Instead of sensing autonomously, CASA radars are designed to operate as a network, collectively adapting to the changing needs of end users and the environment; this network approach to scanning is known as distributed collaborative adaptive sensing (DCAS). DCAS optimizes the low-level volume coverage scanning and maximizes the utility of each scanning cycle. A test bed of four prototype CASA radars was deployed in southwestern Oklahoma in 2006 and operated continuously while in DCAS mode from March through June of 2007. This paper analyzes three convective events observed during April–May 2007, during CASA’s intense operation period (IOP), with a special focus on evaluating the benefits and weaknesses of CASA radar system deployment and DCAS scanning strategy of detecting and tracking low-level circulations. Data collected from nearby Weather Surveillance Radar-1988 Doppler (WSR-88D) and CASA radars are compared for mesoscyclones, misocyclones, and low-level vortices. Initial results indicate that the dense, overlapping coverage at low levels provided by the CASA radars and the high temporal (60 s) resolution provided by DCAS give forecasters more detailed feature continuity and tracking. Moreover, the CASA system is able to resolve a whole class of circulations—misocyclones—far better than the WSR-88Ds. In fact, many of these are probably missed completely by the WSR-88D. The impacts of this increased detail on severe weather warnings are under investigation. Ongoing efforts include enhancing the DCAS data quality and scanning strategy, improving the DCAS data visualization, and developing a robust infrastructure to better support forecast and warning operations.

Human Fibrinogen Binds Edta And Citrate

1981 ◽  
Author(s):  
W Nieuwenhuizen ◽  
A Vermond ◽  
J Hermans
Keyword(s):  
Calcium Ions ◽  
Equilibrium Dialysis ◽  
Strong Dependence ◽  
Direct Interaction ◽  
Heat Stability ◽  
Binding Studies ◽  
Human Fibrinogen ◽  
Direct Binding ◽  
Carboxy Terminal ◽  
Fibrinogen Molecule

It was shown that EDTA and citrate make the carboxy-terminal parts of the γ-chains of fibrinogen more susceptible to plasmin degradation. This is an effect independent of the calcium-chelating properties of those compounds. Furthermore, EDTA prolongs the thrombin times decreases the heat stability and causes the formation of abnormal clots.This suggests a direct interaction of EDTA (and possibly also of citrate) with the fibrinogen molecule thereby causing a conformational change. The interaction of citrate and EDTA with fibrinogen was measured by direct binding studies (equilibrium dialysis).It was found that at pH 7.5 human fibrinogen binds 3.4 molecules of citrate with Kd = 1.4 x 10-4M or 0.4 molecules of EDTA with Kd = 2.2 x 10-5M. Citrate and EDTA compete for the same binding site(s). No binding of acetate could be demonstrated.The binding of EDTA and citrate shows a strong ^-dependence suggesting a (partly) ionogenic binding between charged areas on the fibrinogen molecule and charged groups on EDTA or citrateOur results support the idea that the binding of EDTA and citrate and the concomitant effect on the plasmin attack are independent of the effect of calcium ions

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