scholarly journals Structural polarity of kinetochore microtubules in PtK1 cells.

1981 ◽  
Vol 89 (2) ◽  
pp. 338-345 ◽  
Author(s):  
U Euteneuer ◽  
J R McIntosh
Keyword(s):  
Growth Rate ◽  
Cross Section ◽  
Outer Layer ◽  
Cold Treatment ◽  
Unknown Mechanism ◽  
Fast Growing ◽  
Spindle Poles ◽  
The One ◽  
Uniform Polarity

The polarity of kinetochore microtubules (MTs) has been studied in lysed PtK1 cells by polymerizing hook-shaped sheets of neurotubulin onto walls of preexisting cellular MTs in a fashion that reveals their structural polarity. Three different approaches are presented here: (a) we have screened the polarity of all MTs in a given spindle cross section taken from the region between the kinetochores and the poles, (b) we have determined the polarity of kinetochore MTs are more stable to cold-treated spindles; this approach takes advantage of the fact that kinetochore MTs are more stable to cold treatment than other spindle MTs; and (c) we have tracked bundles of kinetochore MTs from the vicinity of the pole to the outer layer of the kinetochore in cold-treated cells. In an anaphase cell, 90-95% of all MTs in an area between the kinetochores and the poles are of uniform polarity with their plus ends (i.e., fast growing ends) distal to the pole. In cold-treated cells, all bundles of kinetochore MTs show the same polarity; the plus ends of the MTs are located at the kinetochores. We therefore conclude that kinetochore MTs in both metaphase and anaphase cells have the same polarity as the aster MTs in each half-spindle. These results can be interpreted in two ways: (a) virtually all MTs are initiated at the spindle poles and some of the are "captured" by matured kinetochores using an as yet unknown mechanism to bind the plus ends of existing MTs; (b) the growth of kinetochore MTs is initiated at the kinetochore in such a way that the fast growing MT end is proximal to the kinetochore. Our data are inconsistent with previous kinetochore MT polarity determinations based on growth rate measurements in vitro. These studies used drug-treated cells from which chromosomes were isolated to serve as seeds for initiation of neurotubule polymerization. It is possible that under these conditions kinetochores will initiate MTs with a polarity opposite to the one described here.

scholarly journals SFXN1 is a mitochondrial serine transporter required for one-carbon metabolism

Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. eaat9528 ◽  
Author(s):  
Nora Kory ◽  
Gregory A. Wyant ◽  
Gyan Prakash ◽  
Jelmi uit de Bos ◽  
Francesca Bottanelli ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Mitochondrial Membrane ◽  
Mitochondrial Pathway ◽  
Genetic Screen ◽  
Inner Mitochondrial Membrane ◽  
Unknown Mechanism ◽  
One Carbon Metabolism ◽  
The One ◽  
Mitochondrial Membrane Protein

One-carbon metabolism generates the one-carbon units required to synthesize many critical metabolites, including nucleotides. The pathway has cytosolic and mitochondrial branches, and a key step is the entry, through an unknown mechanism, of serine into mitochondria, where it is converted into glycine and formate. In a CRISPR-based genetic screen in human cells for genes of the mitochondrial pathway, we found sideroflexin 1 (SFXN1), a multipass inner mitochondrial membrane protein of unclear function. Like cells missing mitochondrial components of one-carbon metabolism, those null for SFXN1 are defective in glycine and purine synthesis. Cells lacking SFXN1 and one of its four homologs, SFXN3, have more severe defects, including being auxotrophic for glycine. Purified SFXN1 transports serine in vitro. Thus, SFXN1 functions as a mitochondrial serine transporter in one-carbon metabolism.

scholarly journals Comparative Study of Growth Statistics of Two Species of Paulownia and Optimization of Rooting Methods

2019 ◽  
Vol 6 (1) ◽  
pp. 11-15
Author(s):  
Hari Krishna Saiju ◽  
Abhishesh Bajracharya ◽  
Brishav Rajbahak ◽  
Stuti Ghimire
Keyword(s):  
Growth Rate ◽  
Musical Instruments ◽  
Shoot Length ◽  
Ms Medium ◽  
High Quality ◽  
Paulownia Tomentosa ◽  
Fast Growing ◽  
The Family

Paulownia is a fast-growing woody tree, native to the forests of China. It belongs to the family Scrophulariaceae and is mainly used as a source of wood for furniture and musical instruments. Due to its fast-growing nature and high-quality of wood, there has been growing interest in cultivation and research of Paulownia in Nepal. Growth comparison was performed by measuring shoot length in in vitro condition. Among two species of Paulownia - Paulownia tomentosa (Thunb.) Steud and Paulownia fortuneii (Seem.) Hemsl., the growth rate of P. tomentosa was found to be 0.355 cm/week while that of P. fortuneii was found to be 0.637 cm/week in in-vitro conditions in MS medium supplemented with 0.1 mg/l NAA and 1mg/l BAP. Optimization of rooting methods was also performed, in which, sand rooting was found to be easier and more effective than in-vitro rooting. Dipping the plantlets in 1 mg/l of NAA was found to produce longer and denser roots than lower or higher concentrations during sand rooting.

scholarly journals XMAP215 promotes microtubule catastrophe by disrupting the growing microtubule end

2020 ◽  
Author(s):  
Veronica Farmer ◽  
Göker Arpağ ◽  
Sarah Hall ◽  
Marija Zanic
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Fast Growth ◽  
Fast Growing ◽  
Microtubule Stability ◽  
Large Fluctuations ◽  
Microtubule Growth ◽  
Enhanced Stability

ABSTRACTThe GTP-tubulin cap is widely accepted to protect microtubules against catastrophe. The GTP-cap size is thought to increase with the microtubule growth rate, presumably endowing fast-growing microtubules with enhanced stability. It is unknown what GTP-cap properties permit frequent microtubule catastrophe despite fast growth. Here, we investigate microtubules grown in vitro in the presence and absence of the microtubule polymerase XMAP215. Using EB1 as a GTP-cap marker, we find that GTP-cap size increases regardless of whether growth acceleration is achieved by increasing tubulin concentration or by XMAP215. In spite of the increased mean GTP-cap size, microtubules grown with XMAP215 display increased catastrophe frequency, in contrast to microtubules grown with more tubulin, for which catastrophe is abolished. However, microtubules polymerized with XMAP215 have large fluctuations in growth rate and EB1 intensity; display tapered and curled ends; and undergo catastrophe at faster growth rates and with higher EB1 end-localization. Our results underscore the role of growth irregularities in overall microtubule stability.

Evaluation of the presence of double-stranded RNA in Ceratocystis ulmi

1985 ◽  
Vol 63 (2) ◽  
pp. 297-300 ◽  
Author(s):  
J. G. Hoch ◽  
S. M. Tavantzis ◽  
R. J. Campana ◽  
S. L. Anagnostakis
Keyword(s):  
Growth Rate ◽  
Mating Type ◽  
Mating Types ◽  
Double Stranded Rna ◽  
Fast Growing ◽  
Molecular Weights ◽  
Clear Association ◽  
Dsrna Species

Nineteen cultures of Ceratocystis ulmi were classified by mating type and growth rate in vitro. Eleven of the cultures contained double-stranded RNA (dsRNA) with 52% of the segments having molecular weights (MWs) ranging from 1.5 × 106 to 2.0 × 106. Eight of 11 fast-growing (aggressive) isolates contained one to five dsRNA segments with MWs ranging from 0.6 × 106 to 3.1 × 106, whereas 3 of 8 slower growing (nonaggressive) cultures had one or two dsRNA species with MWs ranging from 1.8 × 106 to 2.7 × 106. In addition, cultures with both A and B mating types were found to either contain or lack dsRNA. Thus, there was no clear association between the presence of dsRNA or specific components of dsRNA and aggressiveness or nuclear mating type in the cultures of C. ulmi examined in this study.

Studies on Thrombolysis with Streptokinase

1971 ◽  
Vol 25 (02) ◽  
pp. 354-378 ◽  
Author(s):  
R Gottlob ◽  
L Stockinger ◽  
U Pötting ◽  
G Schattenmann
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Whole Blood ◽  
Jugular Vein ◽  
Thin Sections ◽  
The Third ◽  
Morphological Findings ◽  
Blood Clots ◽  
Arteries And Veins

SummaryIn vitro whole blood clots of various ages, experimental thrombi produced in the jugular vein of rabbits and human thrombi from arteries and veins were examined in semi-thin sections and by means of electron microscopy.In all types of clots examined a typical course of retraction was found. Retraction starts with a dense excentrical focus which grows into a densification ring. After 24 hours the entire clot becomes almost homogeneously dense; later a secondary swelling sets in.Shortly after coagulation the erythrocytes on the rim of the clot are bi-concave discs. They then assume the shape of crenate spheres, turn into smooth spheres and finally become indented ghosts which have lost the largest part of their contents. In the inner zone, which makes up the bulk of the clot, we observed bi-concave discs prior to retraction. After retraction we see no crenations but irregularly shaped erythrocytes. Once the secondary swelling sets in, the cross-section becomes polygonal and later spherical. After extensive hemolysis we observe the “retiform thrombus” made up of ghosts.Experimental and clinical thrombi present the same morphology but are differentiated from in vitro clots by: earlier hemolysis, immigration of leukocytes, formation of a rim layer consisting of fibrin and thrombocytes, and the symptoms of organization. Such symptoms of organization which definitely will prevent lysis with streptokinase were found relatively late in experimental and clinical thrombi. Capillary buds and capillary loops were never found in clinical thrombi prior to the third month.The morphological findings agree with earlier physical and enzymatic investigations. The observation that phenomena of reorganization occur relatively late and frequently only in the rim areas of large thrombi explains why lytic therapy is possible in some of the chronic obliterations.

scholarly journals Structural comparison of CD163 SRCR5 from different species sheds some light on its involvement in porcine reproductive and respiratory syndrome virus-2 infection in vitro

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Hongfang Ma ◽  
Rui Li ◽  
Longguang Jiang ◽  
Songlin Qiao ◽  
Xin-xin Chen ◽  
...  
Keyword(s):  
Scavenger Receptor ◽  
Host Cells ◽  
Respiratory Syndrome Virus ◽  
Swine Industry ◽  
Prrs Virus ◽  
Rich Domain ◽  
Serious Disease ◽  
The One ◽  
And Control

AbstractPorcine reproductive and respiratory syndrome (PRRS) is a serious disease burdening global swine industry. Infection by its etiological agent, PRRS virus (PRRSV), shows a highly restricted tropism of host cells and has been demonstrated to be mediated by an essential scavenger receptor (SR) CD163. CD163 fifth SR cysteine-rich domain (SRCR5) is further proven to play a crucial role during viral infection. Despite intense research, the involvement of CD163 SRCR5 in PRRSV infection remains to be elucidated. In the current study, we prepared recombinant monkey CD163 (moCD163) SRCR5 and human CD163-like homolog (hCD163L1) SRCR8, and determined their crystal structures. After comparison with the previously reported crystal structure of porcine CD163 (pCD163) SRCR5, these structures showed almost identical structural folds but significantly different surface electrostatic potentials. Based on these differences, we carried out mutational research to identify that the charged residue at position 534 in association with the one at position 561 were important for PRRSV-2 infection in vitro. Altogether the current work sheds some light on CD163-mediated PRRSV-2 infection and deepens our understanding of the viral pathogenesis, which will provide clues for prevention and control of PRRS.

scholarly journals Comparative In Vitro Evaluation of the Primary Stability in D3 Synthetic Bone of Two Different Shapes and Pitches of the Implant Threads

2021 ◽  
Vol 11 (12) ◽  
pp. 5612
Author(s):  
Stefano Fanali ◽  
Margherita Tumedei ◽  
Pamela Pignatelli ◽  
Alessandra Lucchese ◽  
Francesco Inchingolo ◽  
...  
Keyword(s):  
Surgical Techniques ◽  
Primary Stability ◽  
Implant Design ◽  
Insertion Torque ◽  
Synthetic Bone ◽  
One Stage ◽  
Prosthetic Joint ◽  
Joint Connection ◽  
The One

Background: Implant primary stability can be affected by several factors related to implant macrogeometry, local anatomy, and surgical techniques. The aim of this research was to study primary stability on polyurethane foam sheets of wide-threaded implant design compared to narrow-threaded implants. Materials and methods: Two different implant designs were positioned on D3 density polyurethane blocks in a standardized environment: the wide-threaded implant and the narrow-threaded implant, for a total of 160 specimens. Moreover, for each group, two different sizes were considered: 3.8mm × 12mm and 4.8mm × 12 mm. The insertion torque (IT) values, the removal strength (RT), and the Periotest analyses were evaluated. Results: A significantly higher IT and RT was reported for wide-threaded implants and two-stage implants (p < 0.01), compared to the narrow-threaded implants. The diameters seemed to provide a significant effect on the primary stability for both implants’ geometry (p < 0.01). A higher mean of the one-stage implant was evident in the Periotest measurements (p < 0.01). Conclusions: Both of the implants showed sufficient stability in polyurethane artificial simulation, while the wide-threaded implant design showed a higher primary stability on alveolar cancellous synthetic bone in vitro. Additionally, the prosthetic joint connection seemed to have a determinant effect on Periotest analysis, and the one-stage implants seemed to provide a high stability of the fixture when positioned in the osteotomy, which could be important for the immediate loading protocol.

scholarly journals Efficient Cryopreservation of Populus tremula by In Vitro-Grown Axillary Buds and Genetic Stability of Recovered Plants

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 77
Author(s):  
Elena O. Vidyagina ◽  
Nikolay N. Kharchenko ◽  
Konstantin A. Shestibratov
Keyword(s):  
Survival Rate ◽  
Axillary Buds ◽  
Long Term Storage ◽  
Average Survival ◽  
Transgenic Lines ◽  
Ssr Loci ◽  
One Step ◽  
The One

Axillary buds of in vitro microshoots were successfully frozen at –196 °C by the one-step freezing method using the protective vitrification solution 2 (PVS2). Microshoots were taken from 11 transgenic lines and three wild type lines. Influence of different explant pretreatments were analyzed from the point of their influence towards recovery after cryopreservation. It was found out that the use of axillary buds as explants after removal of the apical one increases recovery on average by 8%. The cultivation on growth medium of higher density insignificantly raises the regenerants survival rate. Pretreatment of the osmotic fluid (OF) shows the greatest influence on the survival rate. It leads to the increase in survival rate by 20%. The cryopreservation technology providing regenerants average survival rate of 83% was developed. It was based on the experimental results obtained with explant pretreatment. Incubation time in liquid nitrogen did not affect the explants survival rate after thawing. After six months cryostorage of samples their genetic variability was analyzed. Six variable simple sequence repeat (SSR) loci were used to analyze genotype variability after the freezing-thawing procedure. The microsatellite analysis showed the genetic status identity of plants after cryopreservation and of the original genotypes. The presence of the recombinant gene in the transgenic lines after cryostorage were confirmed so as the interclonal variation in the growth rate under greenhouse conditions. The developed technique is recommended for long-term storage of various breeding and genetically modified lines of aspen plants, as it provides a high percentage of explants survival with no changes in genotype.

scholarly journals On the Tidal Prism: The Roles of Basin Extension, Bottom Friction and Inlet Cross-Section

2021 ◽  
Vol 9 (1) ◽  
pp. 88
Author(s):  
Marco Petti ◽  
Sara Pascolo ◽  
Silvia Bosa ◽  
Nadia Busetto
Keyword(s):  
Cross Section ◽  
Bottom Friction ◽  
Static Method ◽  
Tidal Prism ◽  
Empirical Relationships ◽  
Cross Sectional ◽  
Asymptotic Regime ◽  
Static Regime ◽  
The One ◽  
Basin Area

The prism of the Lignano tidal inlet was approximately constant over the last forty years, although the section width has halved. This has led to questions concerning the factors that most influence the tidal prism, and on the applicability of the well-known A–P relationship. A conceptual scheme of the sea–channel–lagoon system has been used to perform a sensitivity analysis of different parameters that characterize both the basin and the inlet cross-section. A 2D hydrodynamic model has been applied to evaluate the prism and compare it to the one derived by a static method, which is the basis of the analytical derivation of the A–P linkage. Three regimes have been found in the prism variability as a function of the basin extension: a linear static regime between prism and basin area; an asymptotic regime in which the prism depends only on the basin bottom friction; and an intermediate one. In addition, the roles of the inlet and channel sizes on the prism value have been investigated. The results, compared to the empirical relationships between the prism and the inlet cross-section, show that a variation in the cross-sectional area does not always corresponds to a change in tidal prism.

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