Journal articles on the topic 'Replicated Defects'
To see the other types of publications on this topic, follow the link: Replicated Defects.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Replicated Defects.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Dong, Han-Quan, and Yue-Xin Du. "The study of copy number variations in the regions of PRKAB2 and PPM1K among congenital heart defects patients." Revista da Associação Médica Brasileira 65, no. 6 (June 2019): 786–90. http://dx.doi.org/10.1590/1806-9282.65.6.786.
Full textAbstract:
SUMMARY OBJECTIVE: This study was to assess the genetic association of copy number variations in two genes (PRKAB2 and PPM1K) located in two regions (tetralogy of Fallot and ventricular septal defect) in a Chinese Han population. METHODS: A total of 200 congenital heart disease patients (100 tetralogy of Fallot patients and 100 ventricular septal defect patients) and 100 congenital heart defect-free controls were recruited, and quantitative real-time PCR analysis was used to replicate the association of two copy number variations with congenital heart defects in a Chinese Han population. RESULTS: One deletion at PRKAB2 and one duplication at PPM1K were found in two of the tetralogy of Fallot patients, respectively; while all these regions were duplicated in both ventricular septal defect patients and in the 100 congenital heart defects-free controls. CONCLUSIONS: We replicated the copy number variations at the disease-candidate genes of PRKAB2 and PPM1K with tetralogy of Fallot in a Chinese Han population, and in patients with ventricular septal defect mutations in these two genes were not found. These results indicate the same molecular population genetics exist in these two genes with different ethnicity. This shows that these two genes are possibly specific pf tetralogy of Fallot candidates.
2
ul Hassan, Jawad, and Peder Bergman. "Influence of Structural Defects on Carrier Lifetime in 4H Epitaxial Layers, Studied by High Resolution Optical Lifetime Mapping." Materials Science Forum 615-617 (March 2009): 255–58. http://dx.doi.org/10.4028/www.scientific.net/msf.615-617.255.
Full textAbstract:
Thick 4H-SiC epitaxial layers have been characterized using high-resolution lifetime mapping. The lifetime maps are obtain by the detection of photoluminescence decay of the band gap emission. Full wafers mappings with 200 m resolution reveal lifetime variations that can be associated with structural defects replicated from the substrate, and variations in epitaxial growth conditions due to the susceptor design. High resolution mapping over smaller regions with down to 20 m step size, reveals local lifetime reductions associated with different structural defects in the epitaxial layer. Identified defects that influence the lifetime are the carrot defect, different types of in-grown stacking faults, and an unidentified defect associated with a pair of basal plane dislocations on the surface. Also clusters of threading screw dislocations, probably originating from a dissociated micropipe in the substrate, are found to reduce the lifetime.
3
Pilkey, A. K., C. J. Bayley, and M. Györffy. "Influence of Surface Defect Geometry on the Localization and Failure of AA6111 Sheet: Necking versus Shear." Materials Science Forum 519-521 (July 2006): 131–38. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.131.
Full textAbstract:
The influence of surface defect geometry on the localization and failure behaviour of AA6111 sheet has been investigated through experimentation and numerical modelling. A series of uniaxial tensile samples were produced with idealized top and bottom surface defects (i.e. grooves), located either symmetrically or asymmetrically on the opposing surfaces. The symmetric arrangement corresponds to the “groove-like” initial imperfection of the classical Marciniak- Kuczyński (M-K) model. Experimental results indicate that both the symmetry of the defects and their wavelength have a profound effect on the resulting mode of localization and failure as well as on the limit strains. Specifically, symmetric surface defects are seen to induce localization and failure through simple necking, whereas asymmetric defects tend to promote macroscopic, throughthickness shearing. Furthermore, asymmetric surface defect geometries are found to produce lower limit strains in the AA6111 sheet under study for defect wavelengths below about 1.5 mm, while the reverse is true when defect wavelengths are above 1.5 mm. Finite element method (FEM) modelling simulations are also presented, demonstrating that the experimentally-observed trends in localization and failure behaviour can be replicated using a mixed isotropic-kinematic hardening implementation of the Gurson-Tvergaard-Needleman (GTN) material model.
4
Finkelstein, Arkady, and Dmitry Husnullin. "Irreversible Thermal Expansion of Replicated Aluminium Foam." Acta Metallurgica Slovaca 24, no. 2 (June 28, 2018): 156. http://dx.doi.org/10.12776/ams.v24i2.1066.
Full textAbstract:
There was found irreversible thermal expansion of large items made of the replicated aluminium foam during the extraction of soluble filler from Al-NaCl composite. Sources of the phenomena were investigated. The expansion is discovered to be caused by incomplete contraction of the porous metal due to oxidation of its internal porous surface during thermal cycling with air and water presence. Significant role of oxide film defects in the expansion process was exposed. There was gained information on dependencies of the irreversible thermal expansion on temperature of the extraction process and metal foam pore size. Measurements of the expansion dynamics showed its finite character. It was also noted that the expansion is limited by the thermal expansion coefficient of used alloy. Finally correction coefficients were obtained that, being applied to nominal sizes of a porous part, compensates the expansion.
5
Pattappa, Girish, Jonas Krueckel, Ruth Schewior, Dustin Franke, Alexander Mench, Matthias Koch, Johannes Weber, et al. "Physioxia Expanded Bone Marrow Derived Mesenchymal Stem Cells Have Improved Cartilage Repair in an Early Osteoarthritic Focal Defect Model." Biology 9, no. 8 (August 17, 2020): 230. http://dx.doi.org/10.3390/biology9080230.
Full textAbstract:
Focal early osteoarthritis (OA) or degenerative lesions account for 60% of treated cartilage defects each year. The current cell-based regenerative treatments have an increased failure rate for treating degenerative lesions compared to traumatic defects. Mesenchymal stem cells (MSCs) are an alternative cell source for treating early OA defects, due to their greater chondrogenic potential, compared to early OA chondrocytes. Low oxygen tension or physioxia has been shown to enhance MSC chondrogenic matrix content and could improve functional outcomes of regenerative therapies. The present investigation sought to develop a focal early OA animal model to evaluate cartilage regeneration and hypothesized that physioxic MSCs improve in vivo cartilage repair in both, post-trauma and focal early OA defects. Using a rabbit model, a focal defect was created, that developed signs of focal early OA after six weeks. MSCs cultured under physioxia had significantly enhanced in vitro MSC chondrogenic GAG content under hyperoxia with or without the presence of interleukin-1β (IL-1β). In both post-traumatic and focal early OA defect models, physioxic MSC treatment demonstrated a significant improvement in cartilage repair score, compared to hyperoxic MSCs and respective control defects. Future investigations will seek to understand whether these results are replicated in large animal models and the underlying mechanisms involved in in vivo cartilage regeneration.
6
Fang, Lei, and Katherine R. Spindler. "E1A-CR3 Interaction-Dependent and -Independent Functions of mSur2 in Viral Replication of Early Region 1A Mutants of Mouse Adenovirus Type 1." Journal of Virology 79, no. 6 (March 15, 2005): 3267–76. http://dx.doi.org/10.1128/jvi.79.6.3267-3276.2005.
Full textAbstract:
ABSTRACT mSur2, a subunit of the Mediator complex, is required for efficient mouse adenovirus type 1 (MAV-1) replication (L. Fang, J. L. Stevens, A. J. Berk, and K. R. Spindler, J. Virol. 78:12888-12900, 2004). We examined the contributions of early-region 1A (E1A) to mSur2 function in MAV-1 replication with E1A mutant viruses. At a multiplicity of infection (MOI) of 1, viruses containing CR3 replicated better in Sur2+/+ mouse embryonic fibroblasts (MEFs) than in Sur2−/− MEFs. In contrast, viruses lacking CR3 replicated no better in Sur2+/+ than in Sur2−/− MEFs. This result supports the hypothesis that the E1A CR3-mSur2 interaction is important for MAV-1 replication. However, at an MOI of 0.05, viruses lacking CR3 showed replication defects in Sur2−/− MEFs compared to Sur2+/+ MEFs, suggesting an E1A CR3 interaction-independent function of mSur2 in MAV-1 replication in cell culture. Paradoxically, CR1Δ, CR2Δ, and CR3Δ mutant viruses replicated slightly more efficiently than wild-type (wt) MAV-1 and E1A null mutant viruses in Sur2−/− MEFs at an MOI of 0.05. Coinfection of Sur2−/− MEFs with wt MAV-1 and CR1Δ, CR2Δ, or CR3Δ mutant viruses rescued the defects of wt MAV-1 replication. This result suggests that an inhibiting effect on wt E1A protein expression and/or E1A function might account for the severe viral replication defect of MAV-1 in Sur2−/− MEFs at an MOI of 0.05. Moreover, titrations of virus yields from infected brains of inbred strains of mice showed that E1A null and CR3Δ mutant viruses had a significant defect in virus replication compared to wt MAV-1. This result supports the hypothesis that the MAV-1 E1A-mSur2 interaction is important in MAV-1 replication in mice.
7
Quesada-López, Christian, Erika Hernandez-Agüero, and Marcelo Jenkins. "Characterization of software testing practices: A replicated survey in Costa Rica." Journal of Software Engineering Research and Development 7 (December 19, 2019): 6. http://dx.doi.org/10.5753/jserd.2019.472.
Full textAbstract:
Software testing is an essential activity in software development projects for delivering high quality products. In a previous study, we reported the results of a survey of software engineering practices in the Costa Rican industry. To make a more in depth analysis of the specific software testing practices among practitioners, we replicated a previous survey conducted in South America. Our objective was to characterize the state of the practice based on practitioners use and perceived importance of those practices. This survey evaluated 42 testing practices grouped in three categories: processes, activities and tools. A total of 92 practitioners responded to the survey. The participants indicated that: (1) tasks for recording of the results of tests, documentation of test procedures and cases, and re-execution of tests when the software is modified are useful and important for software testing practitioners. (2) Acceptance and system testing are the two most useful and important testing types. (3) Tools for recording defects and the effort to fix them (bug tracking) and the availability of a test database for reuse are useful and important. Regarding use and implementation of practices, the participants stated that (4) Planning and designing of software testing before coding and evaluating the quality of test artifacts are not a regular practice. (5) There is a lack of measurement of defect density and test coverage in the industry; and (6) tools for automatic generation of test cases and for estimating testing effort are rarely used. This study gave us a first glance at the state of the practice in software testing in a thriving and very dynamic industry that currently employs most of our computer science professionals. The benefits are twofold: for academia, it provides us with a road map to revise our academic offer, and for practitioners it provides them with a first set of data to benchmark their practices.
8
Bouck, David, and Kerry Bloom. "The role of centromere-binding factor 3 (CBF3) in spindle stability, cytokinesis, and kinetochore attachment." Biochemistry and Cell Biology 83, no. 6 (December 1, 2005): 696–702. http://dx.doi.org/10.1139/o05-161.
Full textAbstract:
The spindle midzone is critical for spindle stability and cytokinesis. Chromosomal passenger proteins relocalize from chromosomes to the spindle midzone after anaphase onset. The recent localization of the inner-kinetochore, centromere-binding factor 3 (CBF3) complex to the spindle midzone in budding yeast has led to the discovery of novel functions for this complex in addition to its essential role at kinetochores. In G1/S cells, CBF3 components are detected along dynamic microtubules, where they can "search-and-capture" newly replicated centromeres. During anaphase, CBF3 is transported to the microtubule plus-ends of the spindle midzone. Consistent with this localization, cells containing a mutation in the CBF3 subunit Ndc10p show defects in spindle stability during anaphase. In addition, ndc10-1 cells show defects during cytokinesis, resulting in a defect in cell abscission. These results highlight the importance of midzone-targeted proteins in coordinating mitosis with cell division. Here we discuss these findings and explore the significance of CBF3 transport to microtubule plus-ends at the spindle midzone.Key words: spindle midzone, passenger protein, inner centromere protein (INCENP), microtubule plus-end.
9
Heinlein, Sebastian, Peter Cawley, and Thomas Vogt. "Validation of a procedure for the evaluation of the performance of an installed structural health monitoring system." Structural Health Monitoring 18, no. 5-6 (September 12, 2018): 1557–68. http://dx.doi.org/10.1177/1475921718798567.
Full textAbstract:
Validation of the performance of guided wave structural health monitoring systems is vital if they are to be widely deployed; testing the damage detection ability of a system by introducing different types of damage at varying locations is very costly and cannot be performed on a system in operation. Estimating the damage detection ability of a system solely by numerical simulations is not possible as complex environmental effects cannot be accounted for. In this study, a methodology was tested and verified that uses finite element simulations to superimpose defect signals onto measurements collected from a defect-free structure. These signals are acquired from the structure of interest under varying environmental and operational conditions for an initial monitoring period. Measurements collected in a previous blind trial of an L-shaped pipe section, onto which a number of corrosion-like defects were introduced, were utilised during this investigation. The growth of three of these defects was replicated using finite element analysis and the simulated reflections were superimposed onto signals collected on the defect-free test pipe. The signal changes and limits of reliable detection predicted from the synthetic defect reflections superimposed on the measurements from the undamaged complex structure agreed well with the changes due to real damage measured on the same structure. This methodology is of great value for any structural health monitoring system as it allows for the minimum detectable defect size to be estimated for specific geometries and damage locations in a quick and efficient manner without the need for multiple test structures while accounting for environmental variations.
10
Enomoto, Shinichiro, Stephen D. Johnston, and Judith Berman. "Identification of a Novel Allele ofSIR3Defective in the Maintenance, but Not the Establishment, of Silencing inSaccharomyces cerevisiae." Genetics 155, no. 2 (June 1, 2000): 523–38. http://dx.doi.org/10.1093/genetics/155.2.523.
Full textAbstract:
AbstractUsing a screen for genes that affect telomere function, we isolated sir3-P898R, an allele of SIR3 that reduces telomeric silencing yet does not affect mating. While sir3-P898R mutations cause no detectable mating defect in quantitative assays, they result in synergistic mating defects in combination with mutations such as sir1 that affect the establishment of silencing. In contrast, sir3-P898R in combination with a cac1 mutation, which affects the maintenance of silencing, does not result in synergistic mating defects. MATa sir3-P898R mutants form shmoo clusters in response to α-factor, and sir3-P898R strains are capable of establishing silencing at a previously derepressed HML locus with kinetics like that of wild-type SIR3 strains. These results imply that Sir3-P898Rp is defective in the maintenance, but not the establishment of silencing. In addition, overexpression of a C-terminal fragment of Sir3-P898R results in a dominant nonmating phenotype: HM silencing is completely lost at both HML and HMR. Furthermore, HM silencing is most vulnerable to disruption by the Sir3-P898R C terminus immediately after S-phase, the time when new silent chromatin is assembled onto newly replicated DNA.
11
Almannai, Mohammed, Azza Salah, and Ayman W. El-Hattab. "Mitochondrial Membranes and Mitochondrial Genome: Interactions and Clinical Syndromes." Membranes 12, no. 6 (June 15, 2022): 625. http://dx.doi.org/10.3390/membranes12060625.
Full textAbstract:
Mitochondria are surrounded by two membranes; the outer mitochondrial membrane and the inner mitochondrial membrane. They are unique organelles since they have their own DNA, the mitochondrial DNA (mtDNA), which is replicated continuously. Mitochondrial membranes have direct interaction with mtDNA and are therefore involved in organization of the mitochondrial genome. They also play essential roles in mitochondrial dynamics and the supply of nucleotides for mtDNA synthesis. In this review, we will discuss how the mitochondrial membranes interact with mtDNA and how this interaction is essential for mtDNA maintenance. We will review different mtDNA maintenance disorders that result from defects in this crucial interaction. Finally, we will review therapeutic approaches relevant to defects in mitochondrial membranes.
12
Arrigo, Angelo B., and Jiuann-Huey Ivy Lin. "Endocytic Protein Defects in the Neural Crest Cell Lineage and Its Pathway Are Associated with Congenital Heart Defects." International Journal of Molecular Sciences 22, no. 16 (August 16, 2021): 8816. http://dx.doi.org/10.3390/ijms22168816.
Full textAbstract:
Endocytic trafficking is an under-appreciated pathway in cardiac development. Several genes related to endocytic trafficking have been uncovered in a mutagenic ENU screen, in which mutations led to congenital heart defects (CHDs). In this article, we review the relationship between these genes (including LRP1 and LRP2) and cardiac neural crest cells (CNCCs) during cardiac development. Mice with an ENU-induced Lrp1 mutation exhibit a spectrum of CHDs. Conditional deletion using a floxed Lrp1 allele with different Cre drivers showed that targeting neural crest cells with Wnt1-Cre expression replicated the full cardiac phenotypes of the ENU-induced Lrp1 mutation. In addition, LRP1 function in CNCCs is required for normal OFT lengthening and survival/expansion of the cushion mesenchyme, with other cell lineages along the NCC migratory path playing an additional role. Mice with an ENU-induced and targeted Lrp2 mutation demonstrated the cardiac phenotype of common arterial trunk (CAT). Although there is no impact on CNCCs in Lrp2 mutants, the loss of LRP2 results in the depletion of sonic hedgehog (SHH)-dependent cells in the second heart field. SHH is known to be crucial for CNCC survival and proliferation, which suggests LRP2 has a non-autonomous role in CNCCs. In this article, other endocytic trafficking proteins that are associated with CHDs that may play roles in the NCC pathway during development, such as AP1B1, AP2B1, FUZ, MYH10, and HECTD1, are reviewed.
13
Turiv, Taras, Jess Krieger, Greta Babakhanova, Hao Yu, Sergij V. Shiyanovskii, Qi-Huo Wei, Min-Ho Kim, and Oleg D. Lavrentovich. "Topology control of human fibroblast cells monolayer by liquid crystal elastomer." Science Advances 6, no. 20 (May 2020): eaaz6485. http://dx.doi.org/10.1126/sciadv.aaz6485.
Full textAbstract:
Eukaryotic cells in living tissues form dynamic patterns with spatially varying orientational order that affects important physiological processes such as apoptosis and cell migration. The challenge is how to impart a predesigned map of orientational order onto a growing tissue. Here, we demonstrate an approach to produce cell monolayers of human dermal fibroblasts with predesigned orientational patterns and topological defects using a photoaligned liquid crystal elastomer (LCE) that swells anisotropically in an aqueous medium. The patterns inscribed into the LCE are replicated by the tissue monolayer and cause a strong spatial variation of cells phenotype, their surface density, and number density fluctuations. Unbinding dynamics of defect pairs intrinsic to active matter is suppressed by anisotropic surface anchoring allowing the estimation of the elastic characteristics of the tissues. The demonstrated patterned LCE approach has potential to control the collective behavior of cells in living tissues, cell differentiation, and tissue morphogenesis.
14
Waltl, Michael, Yoanlys Hernandez, Christian Schleich, Katja Waschneck, Bernhard Stampfer, Hans Reisinger, and Tibor Grasser. "Performance Analysis of 4H-SiC Pseudo-D CMOS Inverter Circuits Employing Physical Charge Trapping Models." Materials Science Forum 1062 (May 31, 2022): 688–95. http://dx.doi.org/10.4028/p-pijkeu.
Full textAbstract:
For the analysis of the characteristics and behavior of circuits prior to fabrication and to improve circuit performance, simulations using Spice tools are typically performed. Such tools rely on static compact models describing the behavior of the individual circuit components such as transistors. In reality, the behavior of the transistors changes over time due to aging, for instance, as a consequence of bias temperature instabilities (BTI). BTI is typically referred to as a drift of the threshold voltage of a transistor due to charge trapping at oxide and interface defects. To explain BTI, power-law-like mathematical expressions are often employed. However, using these simple formulas, the experimental data can only be replicated with limited accuracy. To evaluate the performance of logic inverter circuits made from 4H-SiC CMOS transistors with high precision, we use a physics-based defect model to describe the change of the device behavior from a defect-centric perspective. Our results indicate the limitations of using power-law-like formulas as they lead to an overly pessimistic estimation for circuit parameters.
15
Raghothamachar, Balaji, Yu Yang, Rafael Dalmau, Baxter Moody, H. Spalding Craft, Raoul Schlesser, Michael Dudley, and Zlatko Sitar. "Defect Generation Mechanisms in PVT-Grown AlN Single Crystal Boules." Materials Science Forum 740-742 (January 2013): 91–94. http://dx.doi.org/10.4028/www.scientific.net/msf.740-742.91.
Full textAbstract:
A systematic study on the density and distribution of extended defects in a typical single crystal AlN boule grown by the physical vapor transport (PVT) method has been carried out in order to gain a detailed understanding of the formation of defects such as dislocations and low angle grain boundaries (LAGBs). Boule surface studies reveal that LAGBs are nucleated during initial stages of growth and propagate to the end of growth. Basal plane dislocations (BPDs) are generated during growth due to thermal gradient stresses. Higher BPD densities are found near the LAGBs at the boule edges due to additional stresses from constrained growth. Threading edge dislocations (TEDs) are typically replicated from the seed, and LAGBs composed of arrays of threading dislocation walls are formed to accommodate the c-axis rotation between different groups of threading screw dislocation (TSD) mediated growth centers.
16
Stanley, Nicola R., Kim Findlay, Ben C. Berks, and Tracy Palmer. "Escherichia coli Strains Blocked in Tat-Dependent Protein Export Exhibit Pleiotropic Defects in the Cell Envelope." Journal of Bacteriology 183, no. 1 (January 1, 2001): 139–44. http://dx.doi.org/10.1128/jb.183.1.139-144.2001.
Full textAbstract:
ABSTRACT The Tat system is a recently discovered protein export pathway that serves to translocate folded proteins, often containing redox cofactors, across the bacterial cytoplasmic membrane. Here we report that tat strains are associated with a mutant cell septation phenotype, where chains of up to 10 cells are evident. Mutant strains are also hypersensitive to hydrophobic drugs and to lysis by lysozyme in the absence of EDTA, and they leak periplasmic enzymes, characteristics that are consistent with an outer membrane defect. Both phenotypes are similar to those displayed by strains carrying point mutations in the lpxC (envA) gene. The phenotype was not replicated by mutations affecting synthesis and/or activity of all known or predicted Tat substrates.
17
Sobel, S. G., and M. Snyder. "A highly divergent gamma-tubulin gene is essential for cell growth and proper microtubule organization in Saccharomyces cerevisiae." Journal of Cell Biology 131, no. 6 (December 15, 1995): 1775–88. http://dx.doi.org/10.1083/jcb.131.6.1775.
Full textAbstract:
A Saccharomyces cerevisiae gamma-tubulin-related gene, TUB4, has been characterized. The predicted amino acid sequence of the Tub4 protein (Tub4p) is 29-38% identical to members of the gamma-tubulin family. Indirect immunofluorescence experiments using a strain containing an epitope-tagged Tub4p indicate that Tub4p resides at the spindle pole body throughout the yeast cell cycle. Deletion of the TUB4 gene indicates that Tub4p is essential for yeast cell growth. Tub4p-depleted cells arrest during nuclear division; most arrested cells contain a large bud, replicated DNA, and a single nucleus. Immunofluorescence and nuclear staining experiments indicate that cells depleted of Tub4p contain defects in the organization of both cytoplasmic and nuclear microtubule arrays; such cells exhibit nuclear migration failure, defects in spindle formation, and/or aberrantly long cytoplasmic microtubule arrays. These data indicate that the S. cerevisiae gamma-tubulin protein is an important SPB component that organizes both cytoplasmic and nuclear microtubule arrays.
18
Dovey, Michael, E. Elizabeth Patton, Teresa Bowman, Trista North, Wolfram Goessling, Yi Zhou, and Leonard I. Zon. "Topoisomerase IIα Is Required for Embryonic Development and Liver Regeneration in Zebrafish." Molecular and Cellular Biology 29, no. 13 (April 20, 2009): 3746–53. http://dx.doi.org/10.1128/mcb.01684-08.
Full textAbstract:
ABSTRACT Topoisomerases solve the topological problems encountered by DNA throughout the lifetime of a cell. Topoisomerase IIα, which is highly conserved among eukaryotes, untangles replicated chromosomes during mitosis and is absolutely required for cell viability. A homozygous lethal mutant, can4, was identified in a screen to identify genes important for cell proliferation in zebrafish by utilizing an antibody against a mitosis-specific marker, phospho-histone H3. Mutant embryos have a decrease in the number of proliferating cells and display increases in DNA content and apoptosis, as well as mitotic spindle defects. Positional cloning revealed that the genetic defect underlying these phenotypes was the result of a mutation in the zebrafish topoisomerase IIα (top2a) gene. top2a was found to be required for decatenation but not for condensation in embryonic mitoses. In addition to being required for development, top2a was found to be a haploinsufficient regulator of adult liver regrowth in zebrafish. Regeneration analysis of other adult tissues, including fins, revealed no heterozygous phenotype. Our results confirm a conserved role for TOP2A in vertebrates as well as a dose-sensitive requirement for top2a in adults.
19
Unigwe, Robinson, Oluwaseun Olanrewaju Esan, Chigozie Stanley Ukwueze, and Lawrence Uchenna Egwu. "Histo-Pathology Of Some Internal Organs Of Broiler Chickens Infected With Salmonella enteritidis And Treated With Methanol Extract Of Phyllanthus amarus’ Leaves." Journal of Current Biomedical Research 2, no. 2, Mar-April (April 30, 2022): 187–97. http://dx.doi.org/10.54117/jcbr.v2i2.14.
Full textAbstract:
A 21 d study was carried out to determine the histo-architectural defects associated with spleen, kidney, liver, heart and intestine of Salmonella enteritidis-infected broiler chickens treated with methanol extract of Phyllanthus amarus’ leaves. Sixty (60) 5-week old unsexed Arbor acre broiler chickens on deep litter system were used for the study. They were allotted into 4 groups of T1 = distilled water (control), T2 = Salmonella enteritidis (SE) (1 × 107 CFU/mL, per os), T3 = SE + P. amarus (150 mg/kg), and T4 = SE + enrofloxacin (10 mg/kg, per os) in a completely randomized design and replicated thrice with 5 birds/replicate. One hour prior to inoculation of SE, T3 and T4 received P. amarus and enrofloxacin respectively which continued till expiration of study, whereas T1 and T2 received distilled water and SE respectively via the oral route. At the end of study, a bird per replicate was randomly sampled of the spleen, kidney, liver, heart, and intestine for histopathological examination. There were no observable lesions on T1 plates. Meanwhile, the liver showed multifocal hepatocellular coagulation necrosis, and inflammation (T2), moderate atrophy of hepatic plates (T3) and hepatocellular atrophy, coagulation necrosis and inflammation (T4). Other pathological lesions were seen in T2of all organs due to effect of SE and T4 of the intestine that showcased moderate villi atrophy and cryptal necrosis. This showed that P. amarus was able to alleviate toxic manifestations occasioned by SE inoculation except in the liver where the lesion was however moderate.
20
Mordstein, Markus, Eva Neugebauer, Vanessa Ditt, Birthe Jessen, Toni Rieger, Valeria Falcone, Frederic Sorgeloos, et al. "Lambda Interferon Renders Epithelial Cells of the Respiratory and Gastrointestinal Tracts Resistant to Viral Infections." Journal of Virology 84, no. 11 (March 24, 2010): 5670–77. http://dx.doi.org/10.1128/jvi.00272-10.
Full textAbstract:
ABSTRACT Virus-infected cells secrete a broad range of interferons (IFN) which confer resistance to yet uninfected cells by triggering the synthesis of antiviral factors. The relative contributions of the various IFN subtypes to innate immunity against virus infections remain elusive. IFN-α, IFN-β, and other type I IFN molecules signal through a common, universally expressed cell surface receptor, whereas type III IFN (IFN-λ) uses a distinct cell-type-specific receptor complex for signaling. Using mice lacking functional receptors for type I IFN, type III IFN, or both, we found that IFN-λ plays an important role in the defense against several human pathogens that infect the respiratory tract, such as influenza A virus, influenza B virus, respiratory syncytial virus, human metapneumovirus, and severe acute respiratory syndrome (SARS) coronavirus. These viruses were more pathogenic and replicated to higher titers in the lungs of mice lacking both IFN receptors than in mice with single IFN receptor defects. In contrast, Lassa fever virus, which infects via the respiratory tract but primarily replicates in the liver, was not influenced by the IFN-λ receptor defect. Careful analysis revealed that expression of functional IFN-λ receptor complexes in the lung and intestinal tract is restricted to epithelial cells and a few other, undefined cell types. Interestingly, we found that SARS coronavirus was present in feces from infected mice lacking receptors for both type I and type III IFN but not in those from mice lacking single receptors, supporting the view that IFN-λ contributes to the control of viral infections in epithelial cells of both respiratory and gastrointestinal tracts.
21
Novella, Isabel S., L. Andrew Ball, and Gail W. Wertz. "Fitness Analyses of Vesicular Stomatitis Strains with Rearranged Genomes Reveal Replicative Disadvantages." Journal of Virology 78, no. 18 (September 15, 2004): 9837–41. http://dx.doi.org/10.1128/jvi.78.18.9837-9841.2004.
Full textAbstract:
ABSTRACT Gene expression of the nonsegmented negative-strand RNA viruses is determined by the position of each gene relative to that the single 3′ promoter. The general order of genes among all of the viruses of the order Mononegavirales is highly conserved. In previous work we generated recombinant viruses in which the order of the three central genes of the prototypical rhabdovirus, vesicular stomatitis virus, was rearranged to all six possible permutations. While some of these viruses replicated less well than the wild type when assayed by single-step growth analyses in BSC-1 cells, others replicated as well or slightly better. In the work reported here, we used competition assays to compare the fitness of the viruses with alternative gene orders to that of the wild-type (wt) virus. We found that the relative fitness of these recombinant viruses depended on the multiplicity of infection (MOI) but not on the population size. However, during competitions at low MOI, when complementation cannot compensate for the defects of the populations with rearranged genomes, the virus with the wt gene order was always the most fit.
22
Fahem, Mena Mekhael, Nabeel Hameed Ali, Joseph Ravindra Duddu, and Harleen Luther. "Cold-Injection Molded Gentamicin-Impregnated Polymethyl Methacrylate Implants for Cranioplasty." Operative Neurosurgery 21, no. 4 (July 29, 2021): 248–57. http://dx.doi.org/10.1093/ons/opab257.
Full textAbstract:
Abstract BACKGROUND Cranioplasty can be carried out using either fresh, frozen autologous bone or synthetic substitutes. Ordering artificial 3 dimensional (3D) implants is challenging and time consuming depending on geographical location. In this article, we share our experience using a streamlined process of producing 3D computer-assisted design (CAD) implants using commercially available 3D printers and silicone molds that can be easily replicated with consistent results and are associated with good outcomes. OBJECTIVE To develop patient-specific implants for patients with cranial defects that are accurate, consistent, low cost, and easy to replicate while reducing operator-dependent factors. METHODS We present data from 15 patients who underwent cranioplasty with 3D CAD-designed gentamicin-impregnated bone cement implants that were molded using the cold injection technique. RESULTS The technique was consistent in result production, required little postdemolding manipulation, and showed no dimensional variation in design. Postoperative computed tomography scans showed excellent implant fit, and patients had a low complication rate. CONCLUSION We have demonstrated a technique of mold preparation that is efficient and that produces a reliable result. Polymethyl methacrylate implants molded using this technique showed better reproducibility, higher accuracy, and precision than other types of implants and required minimal postdemolding clean-up.
23
Qin, Shenwei, Brian M. Ward, and Sondra G. Lazarowitz. "The Bipartite Geminivirus Coat Protein Aids BR1 Function in Viral Movement by Affecting the Accumulation of Viral Single-Stranded DNA." Journal of Virology 72, no. 11 (November 1, 1998): 9247–56. http://dx.doi.org/10.1128/jvi.72.11.9247-9256.1998.
Full textAbstract:
ABSTRACT The movement of bipartite geminiviruses such as squash leaf curl virus (SqLCV) requires the cooperative interaction of two essential virus-encoded movement proteins, BR1 and BL1. While the viral coat protein AR1 is not essential for systemic infection, genetic studies demonstrate that its presence masks the defective phenotype of certain BR1 missense mutants, thus suggesting that coat protein does interact with the viral movement pathway. To further examine the mechanism of this interaction, we have constructed alanine-scanning mutants of AR1 and studied them for the ability to mask the infectivity defects of appropriate BR1 mutants, for the ability to target to the nucleus and to bind viral single-stranded DNA (ssDNA) and multimerize, and for effects on the accumulation of replicated viral ssDNA. We identified a specific region of AR1 required for masking of appropriate BR1 mutants and showed that this same region of AR1 was also important for ssDNA binding and the accumulation of viral replicated ssDNA. This region of AR1 also overlapped that involved in multimerization of the coat protein. We also found that the accumulation in protoplasts of single-stranded forms of a recombinant plasmid that included the SqLCV replication origin but was too large to be encapsidated was dependent on the presence of AR1 but did not appear to require encapsidation. These findings extend our model for SqLCV movement, demonstrating that coat protein affects viral movement through its ability to induce the accumulation of replicated viral ssDNA genomes. They further suggested that encapsidation was not required for the AR1-dependent accumulation of viral ssDNA.
24
Hut, Henderika M. J., Willy Lemstra, Engbert H. Blaauw, Gert W. A. van Cappellen, Harm H. Kampinga, and Ody C. M. Sibon. "Centrosomes Split in the Presence of Impaired DNA Integrity during Mitosis." Molecular Biology of the Cell 14, no. 5 (May 2003): 1993–2004. http://dx.doi.org/10.1091/mbc.e02-08-0510.
Full textAbstract:
A well-established function of centrosomes is their role in accomplishing a successful mitosis that gives rise to a pair of identical daughter cells. We recently showed that DNA replication defects and DNA damage in Drosophila embryos trigger centrosomal changes, but it remained unclear whether comparable centrosomal responses can be provoked in somatic mammalian cells. To investigate the centrosomal organization in the presence of impaired DNA integrity, live and ultrastructural analysis was performed on γ-tubulin–GFP and EGFP–α-tubulin–expressing Chinese hamster ovary cells. We have shown that during mitosis in the presence of incompletely replicated or damaged DNA, centrosomes split into fractions containing only one centriole. This results in the formation of multipolar spindles with extra centrosome-like structures. Despite the extra centrosomes and the multipolarity of the spindles, cells do exit from mitosis, resulting in severe division errors. Our data provide evidence of a novel mechanism showing how numerous centrosomes and spindle defects can arise and how this can lead to the formation of aneuploid cells.
25
Robea, Madalina Andreea, Alin Ciobica, Alexandrina-Stefania Curpan, Gabriel Plavan, Stefan Strungaru, Radu Lefter, and Mircea Nicoara. "Preliminary Results Regarding Sleep in a Zebrafish Model of Autism Spectrum Disorder." Brain Sciences 11, no. 5 (April 28, 2021): 556. http://dx.doi.org/10.3390/brainsci11050556.
Full textAbstract:
Autism spectrum disorder (ASD) is one of the most salient developmental neurological diseases and remarkable similarities have been found between humans and model animals of ASD. A common method of inducing ASD in zebrafish is by administrating valproic acid (VPA), which is an antiepileptic drug that is strongly linked with developmental defects in children. In the present study we replicated and extended the findings of VPA on social behavior in zebrafish by adding several sleep observations. Juvenile zebrafish manifested hyperactivity and an increase in ASD-like social behaviors but, interestingly, only exhibited minimal alterations in sleep. Our study confirmed that VPA can generate specific ASD symptoms, indicating that the zebrafish is an alternative model in this field of research.
26
Dudley, Michael, Yi Chen, Xian Rong Huang, and Rong Hui Ma. "Aspects of Dislocation Behavior in SiC." Materials Science Forum 600-603 (September 2008): 261–66. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.261.
Full textAbstract:
A review is presented of the current understanding of the dislocation configurations observed in PVT-grown 4H- and 6H-SiC boules and CVD-grown 4H-SiC homoepitaxial layers. In both PVT-grown boules and CVD-grown epilayers, dislocation configurations are classified according to whether they are growth dislocations, i.e., formed during growth via the replication of dislocations which thread the moving crystal growth front, or result from deformation processes (under either mechanical or electrical stress) immediately following growth, during post growth cooling, i.e., behind the crystal growth front or during device operation. Possible formation mechanisms of growth defects in the PVT grown boules, such as axial screw dislocations and threading edge dislocation walls are proposed. Similarly, possible origins of growth defect configurations in CVD-grown epilayers, such as Frank faults bounded by Frank partials, BPDs and TEDs, are also discussed. In a similar way, the origins of BPD configurations resulting from relaxation of thermal stresses during post-growth cooling of the PVT boules are discussed. Finally, the susceptibility of BPD configurations replicated into CVD grown epilayers from the substrate towards Recombination Enhanced Dislocation Glide (REDG) is discussed.
27
Hartsuiker, Edgar, Jürg Bähler, and Jürg Kohli. "The Role of Topoisomerase II in Meiotic Chromosome Condensation and Segregation in Schizosaccharomyces pombe." Molecular Biology of the Cell 9, no. 10 (October 1998): 2739–50. http://dx.doi.org/10.1091/mbc.9.10.2739.
Full textAbstract:
Topoisomerase II is able to break and rejoin double-strand DNA. It controls the topological state and forms and resolves knots and catenanes. Not much is known about the relation between the chromosome segregation and condensation defects as found in yeasttop2 mutants and the role of topoisomerase II in meiosis. We studied meiosis in a heat-sensitive top2mutant of Schizosaccharomyces pombe. Topoisomerase II is not required until shortly before meiosis I. The enzyme is necessary for condensation shortly before the first meiotic division but not for early meiotic prophase condensation. DNA replication, prophase morphology, and dynamics of the linear elements are normal in thetop2 mutant. The top2 cells are not able to perform meiosis I. Arrested cells have four spindle pole bodies and two spindles but only one nucleus, suggesting that the arrest is nonregulatory. Finally, we show that the arrest is partly solved in atop2 rec7 double mutant, indicating that topoisomerase II functions in the segregation of recombined chromosomes. We suggest that the inability to decatenate the replicated DNA is the primary defect in top2. This leads to a loss of chromatin condensation shortly before meiosis I, failure of sister chromatid separation, and a nonregulatory arrest.
28
Ovejero, Sara, Avelino Bueno, and María P. Sacristán. "Working on Genomic Stability: From the S-Phase to Mitosis." Genes 11, no. 2 (February 20, 2020): 225. http://dx.doi.org/10.3390/genes11020225.
Full textAbstract:
Fidelity in chromosome duplication and segregation is indispensable for maintaining genomic stability and the perpetuation of life. Challenges to genome integrity jeopardize cell survival and are at the root of different types of pathologies, such as cancer. The following three main sources of genomic instability exist: DNA damage, replicative stress, and chromosome segregation defects. In response to these challenges, eukaryotic cells have evolved control mechanisms, also known as checkpoint systems, which sense under-replicated or damaged DNA and activate specialized DNA repair machineries. Cells make use of these checkpoints throughout interphase to shield genome integrity before mitosis. Later on, when the cells enter into mitosis, the spindle assembly checkpoint (SAC) is activated and remains active until the chromosomes are properly attached to the spindle apparatus to ensure an equal segregation among daughter cells. All of these processes are tightly interconnected and under strict regulation in the context of the cell division cycle. The chromosomal instability underlying cancer pathogenesis has recently emerged as a major source for understanding the mitotic processes that helps to safeguard genome integrity. Here, we review the special interconnection between the S-phase and mitosis in the presence of under-replicated DNA regions. Furthermore, we discuss what is known about the DNA damage response activated in mitosis that preserves chromosomal integrity.
29
Long, Matthew E., Stephen R. Lindemann, Jed A. Rasmussen, Bradley D. Jones, and Lee-Ann H. Allen. "Disruption of Francisella tularensis Schu S4iglI,iglJ, andpdpCGenes Results in Attenuation for Growth in Human Macrophages andIn VivoVirulence in Mice and Reveals a Unique Phenotype forpdpC." Infection and Immunity 81, no. 3 (December 28, 2012): 850–61. http://dx.doi.org/10.1128/iai.00822-12.
Full textAbstract:
ABSTRACTFrancisella tularensisis a facultative intracellular bacterial pathogen and the causative agent of tularemia. After infection of macrophages, the organism escapes from its phagosome and replicates to high density in the cytosol, but the bacterial factors required for these aspects of virulence are incompletely defined. Here, we describe the isolation and characterization ofFrancisella tularensissubsp.tularensisstrain Schu S4 mutants that lack functionaliglI,iglJ, orpdpC, three genes of theFrancisellapathogenicity island. Our data demonstrate that these mutants were defective for replication in primary human monocyte-derived macrophages and murine J774 cells yet exhibited two distinct phenotypes. TheiglIandiglJmutants were similar to one another, exhibited profound defects in phagosome escape and intracellular growth, and appeared to be trapped in cathepsin D-positive phagolysosomes. Conversely, thepdpCmutant avoided trafficking to lysosomes, phagosome escape was diminished but not ablated, and these organisms replicated in a small subset of infected macrophages. The phenotype of each mutant strain was reversed bytranscomplementation.In vivovirulence was assessed by intranasal infection of BALB/c mice. The mutants appeared avirulent, as all mice survived infection with 108CFUiglJ-orpdpC-deficient bacteria. Nevertheless, thepdpCmutant disseminated to the liver and spleen before being eliminated, whereas theiglJmutant did not. Taken together, our data demonstrate that the pathogenicity island genes tested are essential forF. tularensisSchu S4 virulence and further suggest thatpdpCmay play a unique role in this process, as indicated by its distinct intermediate phenotype.
30
Das, A., M. Gale, V. Carter, and M. Parsons. "The protein phosphatase inhibitor okadaic acid induces defects in cytokinesis and organellar genome segregation in Trypanosoma brucei." Journal of Cell Science 107, no. 12 (December 1, 1994): 3477–83. http://dx.doi.org/10.1242/jcs.107.12.3477.
Full textAbstract:
Mitosis and cytokinesis are events that are highly coordinated in most eukaryotic cell cycles. African trypanosomes possess a single mitochondrion and must additionally coordinate the organellar division cycle. Here we report that okadaic acid, a potent and specific inhibitor of protein phosphatases PP1and PP2A, uncouples these cycles in living trypanosomes. Cell cycle analysis of treated cells revealed elevated DNA content. Microscopic examination indicated that okadaic acid treatment yielded multinucleate cells with a single mitochondrial network indicating these cells have undergone mitosis but failed to complete cytokinesis. Immunofluorescence analysis of 5-bromo-2-deoxyuridine incorporation demonstrated that the mitochondrial DNA was replicated but did not segregate. The dose response curve for inhibition of the normal cell cycle paralleled that for the in vitro inhibition of protein phosphatase activities with IC50s of approximately 20 nM okadaic acid. These results suggest the involvement of a PP1/PP2A-like activity in coordinating mitosis, mitochondrial DNA division and cytokinesis in trypanosomes.
31
Pereira, Clara, Ana Silva, Cláudia Ferreira, Jorge de Brito, Inês Flores-Colen, and José D. Silvestre. "Uncertainty in Building Inspection and Diagnosis: A Probabilistic Model Quantification." Infrastructures 6, no. 9 (September 1, 2021): 124. http://dx.doi.org/10.3390/infrastructures6090124.
Full textAbstract:
In the field of building inspection and diagnosis, uncertainty is common and surveyors are aware of it, although it is not easily measured. This research proposes a model to quantify uncertainty based on the inspection of rendered façades. A Bayesian network is developed, considering three levels of variables: characteristics of the building, façade and exposure conditions; causes of defects; and defects. To compute conditional probabilities, the results of an inspection campaign from the literature are used. Then, the proposed model is validated and verified using inspection results from another sample, the combination of a strength-of-influence diagram and sensitivity analysis and the application of the model to a case study. Results show that the probabilities computed by the model are a reasonable representation of the hesitancy in decision making during the diagnosis process based only on visual observation. For instance, design and execution errors show lower probabilities due to not being verifiable a posteriori without detailed documentation. The proposed model may be extended and replicated for other building materials in the future, as it may be a useful tool to improve the perception of uncertainty in a key stage of building maintenance or rehabilitation.
32
Sebzda, Eric, Kristen Hoek, Delphine Cendron, Laura Gordy, Patrick Collins, Vrajesh Parekh, Thomas Aune, Sebastian Joyce, and James Thomas. "The transcription factor Klf2 regulates B cell trafficking in a lineage-specific manner (112.21)." Journal of Immunology 186, no. 1_Supplement (April 1, 2011): 112.21. http://dx.doi.org/10.4049/jimmunol.186.supp.112.21.
Full textAbstract:
Abstract Manipulation of homing receptors on effector lymphocytes may provide therapeutic relief from autoimmune disorders; however, few treatments are available to effectively limit B lymphocyte trafficking and prevent effector cell access to peripheral tissues. Understanding the molecular networks that regulate lymphocyte trafficking will be required to develop stable, efficacious drugs that work in a lineage-specific manner. In this regard, our preliminary findings indicate a regulatory link between Kruppel-like factor 2 (Klf2) and B cell homing receptors. Conditional excision of Klf2 leads to lineage-specific defects in mature B cell compartmentalization including displacement of marginal zone (MZ) B cells in the spleen, aberrant trafficking of follicular (FO) B cells, and an absence of peritoneal B1 lymphocytes. These phenotypes are quickly replicated in vivo following tamoxifen-induced Klf2 excision, consistent with a post-developmental defect in mature B cell homeostasis. Moreover, we demonstrate that Klf2 differentially regulates homing receptor expression in a B cell lineage-specific manner, resulting in functionally altered migration patterns. These results highlight Klf2 as a non-redundant transcription factor involved in naïve B cell homing. In turn this study may provide impetus for the rational design of therapeutics that target the molecular mechanisms governing B cell migration.
33
Gonzalez, Ramon, Wenying Huang, Renee Finnen, Courtney Bragg, and S. J. Flint. "Adenovirus E1B 55-Kilodalton Protein Is Required for both Regulation of mRNA Export and Efficient Entry into the Late Phase of Infection in Normal Human Fibroblasts." Journal of Virology 80, no. 2 (January 15, 2006): 964–74. http://dx.doi.org/10.1128/jvi.80.2.964-974.2006.
Full textAbstract:
ABSTRACT The human adenovirus type 5 (Ad5) E1B 55-kDa protein is required for selective nuclear export of viral late mRNAs from the nucleus and concomitant inhibition of export of cellular mRNAs in HeLa cells and some other human cell lines, but its contributions(s) to replication in normal human cells is not well understood. We have therefore examined the phenotypes exhibited by viruses carrying mutations in the E1B 55-kDa protein coding sequence in normal human fibroblast (HFFs). Ad5 replicated significantly more slowly in HFFs than it does in tumor cells, a difference that is the result of delayed entry into the late phase of infection. The A143 mutation, which specifically impaired export of viral late mRNAs from the nucleus in infected HeLa cells (R. A. Gonzalez and S. J. Flint, J. Virol. 76:4507-4519, 2002), induced a more severe defect in viral mRNA export in HFFs. This observation indicates that the E1B 55-kDa protein regulates mRNA export during the late phase of infection of normal human cells. Other mutants exhibited phenotypes not observed in HeLa cells. In HFFs infected by the null mutant Hr6, synthesis of viral late mRNAs and proteins was severely impaired. Such defects in late gene expression were the result of inefficient progression into the late phase of infection, for viral DNA synthesis was 10-fold less efficient in Hr6-infected HFFs than in cells infected by Ad5. Similar, but less severe, defects in viral DNA synthesis were induced by the insertion mutation H224, which has been reported to inhibit binding of the E1B 55-kDa protein to p53 (C. C. Kao, P. R. Yew, and A. J. Berk, Virology 179:806-814, 1990).
34
Uguagliati, Beatrice, Fiorenza Stagni, Marco Emili, Andrea Giacomini, Carla Russo, Sandra Guidi, and Renata Bartesaghi. "Early Appearance of Dendritic Alterations in Neocortical Pyramidal Neurons of the Ts65Dn Model of Down Syndrome." Developmental Neuroscience 44, no. 1 (December 1, 2021): 23–38. http://dx.doi.org/10.1159/000520925.
Full textAbstract:
Down syndrome (DS), which is due to triplication of chromosome 21, is constantly associated with intellectual disability (ID). ID can be ascribed to both neurogenesis impairment and dendritic pathology. These defects are replicated in the Ts65Dn mouse, a widely used model of DS. While neurogenesis impairment in DS is a fetal event, dendritic pathology occurs after the first postnatal months. Neurogenesis alterations across the life span have been extensively studied in the Ts65Dn mouse. In contrast, there is scarce information regarding dendritic alterations at early life stages in this and other models, although there is evidence for dendritic alterations in adult mouse models. Thus, the goal of the current study was to establish whether dendritic alterations are already present in the neonatal period in Ts65Dn mice. In Golgi-stained brains, we quantified the dendritic arbors of layer II/III pyramidal neurons in the frontal cortex of Ts65Dn mice aged 2 (P2) and 8 (P8) days and their euploid littermates. In P2 Ts65Dn mice, we found a moderate hypotrophy of the apical and collateral dendrites but a patent hypotrophy of the basal dendrites. In P8 Ts65Dn mice, the distalmost apical branches were missing or reduced in number, but there were no alterations in the collateral and basal dendrites. No genotype effects were detected on either somatic or dendritic spine density. This study shows dendritic branching defects that mainly involve the basal domain in P2 Ts65Dn mice and the apical but not the other domains in P8 Ts65Dn mice. This suggests that dendritic defects may be related to dendritic compartment and age. The lack of a severe dendritic pathology in Ts65Dn pups is reminiscent of the delayed appearance of patent dendritic alterations in newborns with DS. This similarly highlights the usefulness of the Ts65Dn model for the study of the mechanisms underlying dendritic alterations in DS and the design of possible therapeutic interventions.
35
Kim, Taekyung. "Recent Progress on the Localization of PLK1 to the Kinetochore and Its Role in Mitosis." International Journal of Molecular Sciences 23, no. 9 (May 8, 2022): 5252. http://dx.doi.org/10.3390/ijms23095252.
Full textAbstract:
The accurate distribution of the replicated genome during cell division is essential for cell survival and healthy organismal development. Errors in this process have catastrophic consequences, such as birth defects and aneuploidy, a hallmark of cancer cells. PLK1 is one of the master kinases in mitosis and has multiple functions, including mitotic entry, chromosome segregation, spindle assembly checkpoint, and cytokinesis. To dissect the role of PLK1 in mitosis, it is important to understand how PLK1 localizes in the specific region in cells. PLK1 localizes at the kinetochore and is essential in spindle assembly checkpoint and chromosome segregation. However, how PLK1 localizes at the kinetochore remains elusive. Here, we review the recent literature on the kinetochore recruitment mechanisms of PLK1 and its roles in spindle assembly checkpoint and attachment between kinetochores and spindle microtubules. Together, this review provides an overview of how the local distribution of PLK1 could regulate major pathways in mitosis.
36
Krawitz, Denise C., Tamar Kama, and Paul D. Kaufman. "Chromatin Assembly Factor I Mutants Defective for PCNA Binding Require Asf1/Hir Proteins for Silencing." Molecular and Cellular Biology 22, no. 2 (January 15, 2002): 614–25. http://dx.doi.org/10.1128/mcb.22.2.614-625.2002.
Full textAbstract:
ABSTRACT Chromatin assembly factor I (CAF-I) is a conserved histone H3/H4 deposition complex. Saccharomyces cerevisiae mutants lacking CAF-I subunit genes (CAC1 to CAC3) display reduced heterochromatic gene silencing. In a screen for silencing-impaired cac1 alleles, we isolated a mutation that reduced binding to the Cac3p subunit and another that impaired binding to the DNA replication protein PCNA. Surprisingly, mutations in Cac1p that abolished PCNA binding resulted in very minor telomeric silencing defects but caused silencing to be largely dependent on Hir proteins and Asf1p, which together comprise an alternative silencing pathway. Consistent with these phenotypes, mutant CAF-I complexes defective for PCNA binding displayed reduced nucleosome assembly activity in vitro but were stimulated by Asf1p-histone complexes. Furthermore, these mutant CAF-I complexes displayed a reduced preference for depositing histones onto newly replicated DNA. We also observed a weak interaction between Asf1p and Cac2p in vitro, and we hypothesize that this interaction underlies the functional synergy between these histone deposition proteins.
37
Calzetta, Nicolás Luis, Marina Alejandra González Besteiro, and Vanesa Gottifredi. "Mus81-Eme1–dependent aberrant processing of DNA replication intermediates in mitosis impairs genome integrity." Science Advances 6, no. 50 (December 2020): eabc8257. http://dx.doi.org/10.1126/sciadv.abc8257.
Full textAbstract:
Chromosome instability (CIN) underpins cancer evolution and is associated with drug resistance and poor prognosis. Understanding the mechanistic basis of CIN is thus a priority. The structure-specific endonuclease Mus81-Eme1 is known to prevent CIN. Intriguingly, however, here we show that the aberrant processing of late replication intermediates by Mus81-Eme1 is a source of CIN. Upon depletion of checkpoint kinase 1 (Chk1), Mus81-Eme1 cleaves under-replicated DNA engaged in mitotic DNA synthesis, leading to chromosome segregation defects. Supplementing cells with nucleosides allows the completion of mitotic DNA synthesis, restraining Mus81-Eme1–dependent DNA damage in mitosis and the ensuing CIN. We found no correlation between CIN arising from nucleotide shortage in mitosis and cell death, which were selectively linked to DNA damage load in mitosis and S phase, respectively. Our findings imply the possibility of optimizing Chk1-directed therapies by inducing cell death while curtailing CIN, a common side effect of chemotherapy.
38
Pereira, Lenore, Ekaterina Maidji, Susan McDonagh, Olga Genbacev, and Susan Fisher. "Human Cytomegalovirus Transmission from the Uterus tothe Placenta Correlates with the Presence of Pathogenic Bacteria andMaternalImmunity." Journal of Virology 77, no. 24 (December 15, 2003): 13301–14. http://dx.doi.org/10.1128/jvi.77.24.13301-13314.2003.
Full textAbstract:
ABSTRACT Prenatal cytomegalovirus infection may cause pregnancy complications such as intrauterine growth restriction and birth defects. How virus from the mother traverses the placenta is unknown. PCR analysis of biopsy specimens of the maternal-fetal interface revealed that DNA sequences from cytomegalovirus were commonly found with those of herpes simplex viruses and pathogenic bacteria. Cytomegalovirus DNA and infected cell proteins were found more often in the decidua than in the placenta, suggesting that the uterus functions as a reservoir for infection. In women with low neutralizing titers, cytomegalovirus replicated in diverse decidual cells and placental trophoblasts and capillaries. In women with intermediate to high neutralizing titers, decidual infection was suppressed and the placenta was spared. Overall, cytomegalovirus virions and maternal immunoglobulin G were detected in syncytiotrophoblasts, villus core macrophages, and dendritic cells. These results suggest that the outcome of cytomegalovirus infection depends on the presence of other pathogens and coordinated immune responses to viral replication at the maternal-fetal interface.
39
Frenz, L. M., and D. M. Glover. "A maternal requirement for glutamine synthetase I for the mitotic cycles of syncytial Drosophila embryos." Journal of Cell Science 109, no. 11 (November 1, 1996): 2649–60. http://dx.doi.org/10.1242/jcs.109.11.2649.
Full textAbstract:
We describe the maternal effect phenotype of a hypomorphic mutation in the Drosophila gene for glutamine synthetase I (GSI). The extent of development of embryos derived from homozygous mutant females is variable, although most mutant embryos fail to survive past germband elongation and none develop into larvae. These embryos are characterised by an increase in the number of yolk-like nuclei following nuclear migration to the cortex. These nuclei appear to fall into the interior of the embryo from the cortex at blastoderm. As they do so, the majority continue to show association with PCNA in synchrony with nuclei at the cortex, suggesting some continuity of the synchrony of DNA replication. However, the occurrence of nuclei that have lost cell cycle synchrony with their neighbours is not uncommon. Immunostaining of mutant embryos revealed a range of mitotic defects, ultimately resulting in nuclear fusion events, division failure or other mitotic abnormalities. A high proportion of these mitotic figures show chromatin bridging at anaphase and telophase consistent with progression through mitosis in the presence of incompletely replicated DNA. GSI is responsible for the ATP-dependent amination of glutamate to produce glutamine, which is required in the formation of amino acids, purines and pyrimidines. We discuss how the loss of glutamine could depress both protein and DNA synthesis and lead to a variety of mitotic defects in this embryonic system that lacks certain checkpoint controls.
40
Esteban, Rosa, and Reed B. Wickner. "A New Non-Mendelian Genetic Element of Yeast That Increases Cytopathology Produced by M1 Double-Stranded RNA in ski Strains." Genetics 117, no. 3 (November 1, 1987): 399–408. http://dx.doi.org/10.1093/genetics/117.3.399.
Full textAbstract:
ABSTRACT The Saccharomyces cerevisiae SKI (superkiller) genes are repressors of replication of M, L-A, and L-BC double-stranded (ds) RNAs; ski strains have an increased M dsRNA copy number and, as a result, are cold-sensitive for growth at 8°. Growth is normal, however, at higher temperatures. We have found a new cytoplasmic genetic element [D] (for disease) that makes M1 dsRNA-containing superkiller strains grow slowly at 30°, not at all at 37°, and only very poorly at 20°. These growth defects require three factors: a chromosomal ski mutation, the presence of M1 dsRNA, and the presence of the new cytoplasmic factor, [D]. We have isolated mutants unable to ma intain [D] (mad), at least one of which is due to mutation of a single chromosomal locus. Further, [D] can be cured by growth at 37-39°. We present evidence that [D] is not M, L-A, L-BC or W dsRNAs or mitochondrial DNA, 2µ DNA, or [psi], but [D] depends on L-A for its maintenance. We also show that [D] is distinct from [B], a cytoplasmic element that allows M1 dsRNA to be stably replicated and maintained in spite of defects in certain chromosomal MAK genes that would otherwise be necessary. [D] activity is blocked by the presence of another extrachromosomal element, called [DIN] (for [D] interference). [D] and [DIN] may be different natural variants of the same molecule.
41
Schneidewind, Arne, Mark A. Brockman, John Sidney, Yaoyu E. Wang, Huabiao Chen, Todd J. Suscovich, Bin Li, et al. "Structural and Functional Constraints Limit Options for Cytotoxic T-Lymphocyte Escape in the Immunodominant HLA-B27-Restricted Epitope in Human Immunodeficiency Virus Type 1 Capsid." Journal of Virology 82, no. 11 (April 2, 2008): 5594–605. http://dx.doi.org/10.1128/jvi.02356-07.
Full textAbstract:
ABSTRACT Control of human immunodeficiency virus type 1 (HIV-1) by HLA-B27-positive subjects has been linked to an immunodominant CD8+ cytotoxic T-lymphocyte (CTL) response targeting the conserved KK10 epitope (KRWIILGLNK263-272) in p24/Gag. Viral escape in KK10 typically occurs through development of an R264K substitution in conjunction with the upstream compensatory mutation S173A, and the difficulty of the virus to escape from the immune response against the KK10 epitope until late in infection has been associated with slower clinical progression. Rare alternative escape mutations at R264 have been observed, but factors dictating the preferential selection of R264K remain unclear. Here we illustrate that while all observed R264 mutations (K, G, Q, and T) reduced peptide binding to HLA-B27 and impaired viral replication, the replicative defects of the alternative mutants were actually less pronounced than those for R264K. Importantly, however, none of these mutants replicated as well as an R264K variant containing the compensatory mutation S173A. In assessing the combined effects of viral replication and CTL escape using an in vitro coculture assay, we further observed that the compensated R264K mutant also displayed the highest replication capacity in the presence of KK10-specific CTLs. Comparisons of codon usage for the respective variants indicated that generation of the R264K mutation may also be favored due to a G-to-A bias in nucleotide substitutions during HIV-1 replication. Together, these data suggest that the preference for R264K is due primarily to the ability of the S173A-compensated virus to replicate better than alternative variants in the presence of CTLs, suggesting that viral fitness is a key contributor for the selection of immune escape variants.
42
Kim, Daniel J., Arvind Venkataraman, Priyanka Caroline Jain, Eleanor P. Wiesler, Melody DeBlasio, Jonathan Klein, Stephanie S. Tu, Seohyuk Lee, Ruslan Medzhitov, and Akiko Iwasaki. "Vitamin B12 and folic acid alleviate symptoms of nutritional deficiency by antagonizing aryl hydrocarbon receptor." Proceedings of the National Academy of Sciences 117, no. 27 (June 22, 2020): 15837–45. http://dx.doi.org/10.1073/pnas.2006949117.
Full textAbstract:
Despite broad appreciation of their clinical utility, it has been unclear how vitamin B12 and folic acid (FA) function at the molecular level to directly prevent their hallmark symptoms of deficiency like anemia or birth defects. To this point, B12 and FA have largely been studied as cofactors for enzymes in the one-carbon (1C) cycle in facilitating the de novo generation of nucleotides and methylation of DNA and protein. Here, we report that B12 and FA function as natural antagonists of aryl hydrocarbon receptor (AhR). Our studies indicate that B12 and FA bind AhR directly as competitive antagonists, blocking AhR nuclear localization, XRE binding, and target gene induction mediated by AhR agonists like 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and 6-formylindolo[3,2-b]carbazole (FICZ). In mice, TCDD treatment replicated many of the hallmark symptoms of B12/FA deficiency and cotreatment with aryl hydrocarbon portions of B12/FA rescued mice from these toxic effects. Moreover, we found that B12/FA deficiency in mice induces AhR transcriptional activity and accumulation of erythroid progenitors and that it may do so in an AhR-dependent fashion. Consistent with these results, we observed that human cancer samples with deficient B12/FA uptake demonstrated higher transcription of AhR target genes and lower transcription of pathways implicated in birth defects. In contrast, there was no significant difference observed between samples with mutated and intact 1C cycle proteins. Thus, we propose a model in which B12 and FA blunt the effect of natural AhR agonists at baseline to prevent the symptoms that arise with AhR overactivation.
43
Gemble, Simon, René Wardenaar, Kristina Keuper, Nishit Srivastava, Maddalena Nano, Anne-Sophie Macé, Andréa E. Tijhuis, et al. "Genetic instability from a single S phase after whole-genome duplication." Nature 604, no. 7904 (March 30, 2022): 146–51. http://dx.doi.org/10.1038/s41586-022-04578-4.
Full textAbstract:
AbstractDiploid and stable karyotypes are associated with health and fitness in animals. By contrast, whole-genome duplications—doublings of the entire complement of chromosomes—are linked to genetic instability and frequently found in human cancers1–3. It has been established that whole-genome duplications fuel chromosome instability through abnormal mitosis4–8; however, the immediate consequences of tetraploidy in the first interphase are not known. This is a key question because single whole-genome duplication events such as cytokinesis failure can promote tumorigenesis9. Here we find that human cells undergo high rates of DNA damage during DNA replication in the first S phase following induction of tetraploidy. Using DNA combing and single-cell sequencing, we show that DNA replication dynamics is perturbed, generating under- and over-replicated regions. Mechanistically, we find that these defects result from a shortage of proteins during the G1/S transition, which impairs the fidelity of DNA replication. This work shows that within a single interphase, unscheduled tetraploid cells can acquire highly abnormal karyotypes. These findings provide an explanation for the genetic instability landscape that favours tumorigenesis after tetraploidization.
44
Davis, Jeanine M., and Randolph G. Gardner. "Harvest Maturity Affects Fruit Yield, Size, and Grade of Fresh-market Tomato Cultivars." HortScience 29, no. 6 (June 1994): 613–15. http://dx.doi.org/10.21273/hortsci.29.6.613.
Full textAbstract:
Eight staked, determinate tomato (Lycopersicon esculentum Mill.) cultivars were harvested when green (before breaker stage) or when pink (breaker stage and riper) in two replicated field studies. In general, total yield and average fruit size were reduced when fruit were harvested at the green stage. Harvest maturity had only a small effect on occurrence of most fruit defects, except fruit cracking, which was more severe for pink than for green fruit in the early season experiment. Although total yields for pink harvested fruit were higher than for green harvested fruit in the early season study, the high incidence of fruit crack in pink fruit resulted in similar yields of U.S. combination grade (U.S. no. 1 and U.S. no. 2) fruit for both treatments. Because the largest fruit often bring a premium price, harvesting fruit when pink probably will result in a higher price per kilogram than harvesting fruit when green. Fruit harvested green, however, are generally firmer, more crack resistant, and require fewer harvests than fruit harvested pink.
45
Chapman, James, Yi Shiau Ng, and Thomas J. Nicholls. "The Maintenance of Mitochondrial DNA Integrity and Dynamics by Mitochondrial Membranes." Life 10, no. 9 (August 26, 2020): 164. http://dx.doi.org/10.3390/life10090164.
Full textAbstract:
Mitochondria are complex organelles that harbour their own genome. Mitochondrial DNA (mtDNA) exists in the form of a circular double-stranded DNA molecule that must be replicated, segregated and distributed around the mitochondrial network. Human cells typically possess between a few hundred and several thousand copies of the mitochondrial genome, located within the mitochondrial matrix in close association with the cristae ultrastructure. The organisation of mtDNA around the mitochondrial network requires mitochondria to be dynamic and undergo both fission and fusion events in coordination with the modulation of cristae architecture. The dysregulation of these processes has profound effects upon mtDNA replication, manifesting as a loss of mtDNA integrity and copy number, and upon the subsequent distribution of mtDNA around the mitochondrial network. Mutations within genes involved in mitochondrial dynamics or cristae modulation cause a wide range of neurological disorders frequently associated with defects in mtDNA maintenance. This review aims to provide an understanding of the biological mechanisms that link mitochondrial dynamics and mtDNA integrity, as well as examine the interplay that occurs between mtDNA, mitochondrial dynamics and cristae structure.
46
Lartigue, Lydia, Yulia Kushnareva, Youngmo Seong, Helen Lin, Benjamin Faustin, and Donald D. Newmeyer. "Caspase-independent Mitochondrial Cell Death Results from Loss of Respiration, Not Cytotoxic Protein Release." Molecular Biology of the Cell 20, no. 23 (December 2009): 4871–84. http://dx.doi.org/10.1091/mbc.e09-07-0649.
Full textAbstract:
In apoptosis, mitochondrial outer membrane permeabilization (MOMP) triggers caspase-dependent death. However, cells undergo clonogenic death even if caspases are blocked. One proposed mechanism involved the release of cytotoxic proteins (e.g., AIF and endoG) from mitochondria. To initiate MOMP directly without side effects, we created a tamoxifen-switchable BimS fusion protein. Surprisingly, even after MOMP, caspase-inhibited cells replicated DNA and divided for ∼48 h before undergoing proliferation arrest. AIF and endoG remained in mitochondria. However, cells gradually lost mitochondrial membrane potential and ATP content, and DNA synthesis slowed to a halt by 72 h. These defects resulted from a partial loss of respiratory function, occurring 4–8 h after MOMP, that was not merely due to dispersion of cytochrome c. In particular, Complex I activity was completely lost, and Complex IV activity was reduced by ∼70%, whereas Complex II was unaffected. Later, cells exhibited a more profound loss of mitochondrial protein constituents. Thus, under caspase inhibition, MOMP-induced clonogenic death results from a progressive loss of mitochondrial function, rather than the release of cytotoxic proteins from mitochondria.
47
Madireddy, Advaitha, Angelica Barreto-Galvez, and B. Hilda Ye. "Understanding the Mechanisms Driving Genomic Instability in Adult T-Cell Leukemia/Lymphoma." Blood 134, Supplement_1 (November 13, 2019): 5042. http://dx.doi.org/10.1182/blood-2019-121565.
Full textAbstract:
Adult T-cell Leukemia/Lymphoma (ATLL) is a T-cell malignancy that results from infection by the retrovirus, human T cell lymphotropic virus-1 (HTLV-1). ATLL is endemic to Japan, the Caribbean regions and Latin America. Despite the rare occurrence of the disease, ATLL is a very aggressive malignancy with limited treatment options. Recent studies show that the ATLL patients diagnosed in North America (NA-ATLL), who are largely from the Caribbean region, have extremely poor prognosis as compared to the Japanese ATLL (J-ATLL) patients. A better understanding of the molecular pathogenesis of NA-ATLL is critical to identifying effective treatment measures for these patients. It has been previously shown that genomic instability including extensive chromosomal variations can be frequently found in ATLLs. However, the underlying mechanisms leading to this instability are unclear. Analysis of the mechanism of HTLV-1 action has revealed that the virus, in addition to hijacking the host cell machinery, disrupts DNA repair mechanisms and cell division processes. While the disruption of repair mechanisms could be held accountable for the accumulation of damage in ATLL cells, the precise nature of this disruption has not been fully understood. In proliferating cells, damage to the DNA occurs or is primarily recognized during DNA replication. This indicates that defective DNA replication could be an important factor driving genomic instability in ATLL cells. Possible involvement of replicative defects in the etiology of ATLL is further strengthened by the fact that genomic instability in ATLL cells has been shown to occur at difficult to replicate genomic regions referred to as common fragile sites. Here, using a powerful locus specific approach called the single molecule analysis of replicated DNA (SMARD), we show that perturbed DNA replication is an inherent component of disease manifestation in ATLL patients. Furthermore, our preliminary findings suggest that these changes in DNA replication can be largely attributed to the EP300 inactivating mutations often found among NA-ATLL patients. This study will help elucidate the molecular mechanisms contributing to the marked chemo-resistant feature of NA-ATLL patients, as compared to J-ATLL patients. In addition to increasing our understanding of the mechanisms contributing to ATLL in general, the results from this study may inform new and mechanism-based treatment paradigms that target the replicative defects of this unique disease. Disclosures No relevant conflicts of interest to declare.
48
Gorchakov, Rodion, Elena Frolova, Stanley Sawicki, Svetlana Atasheva, Dorothea Sawicki, and Ilya Frolov. "A New Role for ns Polyprotein Cleavage in Sindbis Virus Replication." Journal of Virology 82, no. 13 (April 16, 2008): 6218–31. http://dx.doi.org/10.1128/jvi.02624-07.
Full textAbstract:
ABSTRACT One of the distinguishing features of the alphaviruses is a sequential processing of the nonstructural polyproteins P1234 and P123. In the early stages of the infection, the complex of P123+nsP4 forms the primary replication complexes (RCs) that function in negative-strand RNA synthesis. The following processing steps make nsP1+P23+nsP4, and later nsP1+nsP2+nsP3+nsP4. The latter mature complex is active in positive-strand RNA synthesis but can no longer produce negative strands. However, the regulation of negative- and positive-strand RNA synthesis apparently is not the only function of ns polyprotein processing. In this study, we developed Sindbis virus mutants that were incapable of either P23 or P123 cleavage. Both mutants replicated in BHK-21 cells to levels comparable to those of the cleavage-competent virus. They continuously produced negative-strand RNA, but its synthesis was blocked by the translation inhibitor cycloheximide. Thus, after negative-strand synthesis, the ns proteins appeared to irreversibly change conformation and formed mature RCs, in spite of the lack of ns polyprotein cleavage. However, in the cells having no defects in α/β interferon (IFN-α/β) production and signaling, the cleavage-deficient viruses induced a high level of type I IFN and were incapable of causing the spread of infection. Moreover, the P123-cleavage-deficient virus was readily eliminated, even from the already infected cells. We speculate that this inability of the viruses with unprocessed polyprotein to productively replicate in the IFN-competent cells and in the cells of mosquito origin was an additional, important factor in ns polyprotein cleavage development. In the case of the Old World alphaviruses, it leads to the release of nsP2 protein, which plays a critical role in inhibiting the cellular antiviral response.
49
Cavaletto, Noemi, Anna Luganini, and Giorgio Gribaudo. "Inactivation of the Human CytomegalovirusUS20Gene Hampers Productive Viral Replication in Endothelial Cells." Journal of Virology 89, no. 21 (August 26, 2015): 11092–106. http://dx.doi.org/10.1128/jvi.01141-15.
Full textAbstract:
ABSTRACTThe human cytomegalovirus (HCMV)US12gene family includes a group of 10 contiguous genes (US12toUS21) encoding predicted seven-transmembrane-domain (7TMD) proteins that are nonessential for replication within cultured fibroblasts. Nevertheless, inactivation of someUS12family members affects virus replication in other cell types; e.g., deletion ofUS16orUS18abrogates virus growth in endothelial and epithelial cells or in human gingival tissue, respectively, suggesting a role for some US12 proteins in HCMV cell tropism. Here, we provide evidence that another member,US20, impacts the ability of a clinical strain of HCMV to replicate in endothelial cells. Through the use of recombinant HCMV encoding tagged versions of the US20 protein, we investigated the expression pattern, localization, and topology of the US20-encoded protein (pUS20). We show that pUS20 is expressed as a partially glycosylated 7TMD protein which accumulates late in infection in endoplasmic reticulum-derived peripheral structures localized outside the cytoplasmic virus assembly compartment (cVAC). US20-deficient mutants generated in the TR clinical strain of HCMV exhibited major growth defects in different types of endothelial cells, whereas they replicated normally in fibroblasts and epithelial cells. While the attachment and entry phases in endothelial cells were not significantly affected by the absence of US20 protein, US20-null viruses failed to replicate viral DNA and express representative E and L mRNAs and proteins. Taken together, these results indicate that US20 sustains the HCMV replication cycle at a stage subsequent to entry but prior to E gene expression and viral DNA synthesis in endothelial cells.IMPORTANCEHuman cytomegalovirus (HCMV) is a major pathogen in newborns and immunocompromised individuals. A hallmark of HCMV pathogenesis is its ability to productively replicate in an exceptionally broad range of target cells, including endothelial cells, which represent a key target for viral dissemination and replication in the host, and to contribute to both viral persistence and associated inflammation and vascular diseases. Replication in endothelial cells depends on the activities of a set of viral proteins that regulate different stages of the HCMV replication cycle in an endothelial cell type-specific manner and thereby act as determinants of viral tropism. Here, we report the requirement of a HCMV protein as a postentry tropism factor in endothelial cells. The identification and characterization of HCMV endotheliotropism-regulating proteins will advance our understanding of the molecular mechanisms of HCMV-related pathogenesis and help lead to the design of new antiviral strategies able to exploit these functions.
50
Veluthakal, Rajakrishnan, Daleep K. Arora, Marc L. Goalstone, Renu A. Kowluru, and Anjaneyulu Kowluru. "Metabolic Stress Induces Caspase-3 Mediated Degradation and Inactivation of Farnesyl and Geranylgeranyl Transferase Activities in Pancreatic β-Cells." Cellular Physiology and Biochemistry 39, no. 6 (2016): 2110–20. http://dx.doi.org/10.1159/000447907.
Full textAbstract:
Background/Aims: At least 300 prenylated proteins are identified in the human genome; the majority of which partake in a variety of cellular processes including growth, differentiation, cytoskeletal organization/dynamics and vesicle trafficking. Aberrant prenylation of proteins is implicated in human pathologies including cancer; neurodegenerative diseases, retinitis pigmentosa, and premature ageing syndromes. Original observations from our laboratory have demonstrated that prenylation of proteins [small G-proteins and γ-subunits of trimeric G-proteins] is requisite for physiological insulin secretion. Herein, we assessed the impact of metabolic stress [gluco-, lipotoxicity and ER-stress] on the functional status of protein prenylation pathway in pancreatic β-cells. Methods: Farnesyltransferase [FTase] and geranylgeranyltransferase [GGTase] activities were quantified by radioisotopic methods. Caspase-3 activation and FTase/GGTase-α subunit degradation were determined by Western blotting. Results: We observed that metabolic stress activates caspase-3 and induces degradation of the common α-subunit of FTase and GGTase-I in INS-1 832/13 cells, normal rodent islets and human islets leading to functional defects [inactivation] in FTase and GGTase activities. Caspase-3 activation and FTase/GGTase-α degradation were also seen in islets from the Zucker diabetic fatty [ZDF] rat, a model for Type 2 diabetes. Consequential to defects in FTase/GGTase-α signaling, we observed significant accumulation of unprenylated proteins [Rap1] in β-cells exposed to glucotoxic conditions. These findings were replicated in β-cells following pharmacological inhibition of generation of prenylpyrophosphate substrates [Simvastatin] or catalytic activity of prenylating enzymes [GGTI-2147]. Conclusions: Our findings provide the first evidence to suggest that metabolic stress induced dysfunction of the islet β-cell may, in part, be due to defective protein prenylation signaling pathway.