scholarly journals Extensive, Nonrandom Diversity of Excision Footprints Generated by Ds-Like Transposon Ascot-1Suggests New Parallels with V(D)J Recombination

1998 ◽  
Vol 18 (7) ◽  
pp. 4337-4346 ◽  
Author(s):  
Vincent Colot ◽  
Vicki Haedens ◽  
Jean-Luc Rossignol
Keyword(s):  
Extensive Study ◽  
Empty Site ◽  
Site Factors ◽  
Original Sequence ◽  
Ascobolus Immersus ◽  
High Degree ◽  
Hairpin Formation ◽  
Processing Steps ◽  
Color Gene

ABSTRACT Upon insertion, transposable elements can disrupt or alter gene function in various ways. Transposons moving through a cut-and-paste mechanism are in addition often mutagenic when excising because repair of the empty site seldom restores the original sequence. The characterization of numerous excision events in many eukaryotes indicates that transposon excision from a given site can generate a high degree of DNA sequence and phenotypic variation. Whether such variation is generated randomly remains largely to be determined. To this end, we have exploited a well-characterized system of genetic instability in the fungus Ascobolus immersus to perform an extensive study of excision events. We show that this system, which produces many phenotypically and genetically distinct derivatives, results from the excision of a novel Ds-like transposon,Ascot-1, from the spore color gene b2. A unique set of 48 molecularly distinct excision products were readily identified from a representative sample of excision derivatives. Products varied in their frequency of occurrence over 4 orders of magnitude, yet most showed small palindromic nucleotide additions. Based on these and other observations, compelling evidence was obtained for intermediate hairpin formation during the excision reaction and for strong biases in the subsequent processing steps at the empty site. Factors likely to be involved in these biases suggest new parallels between the excision reaction performed by transposons of thehAT family and V(D)J recombination. An evaluation of the contribution of small palindromic nucleotide additions produced by transposon excision to the spectrum of spontaneous mutations is also presented.

Characterization of RF Sputtered ZnO Piezoelectric Films Using Transmission Electron Microscope

1975 ◽  
Vol 33 ◽  
pp. 86-87
Author(s):  
Kemining W. Yeh ◽  
Richard S. Muller ◽  
Wei-Kuo Wu ◽  
Jack Washburn
Keyword(s):  
Integrated Circuit ◽  
Acoustic Waves ◽  
New Technology ◽  
Surface Acoustic Waves ◽  
Electromechanical Properties ◽  
Leading Role ◽  
Saw Devices ◽  
Transmission Electron ◽  
High Degree

Considerable and continuing interest has been shown in the thin film transducer fabrication for surface acoustic waves (SAW) in the past few years. Due to the high degree of miniaturization, compatibility with silicon integrated circuit technology, simplicity and ease of design, this new technology has played an important role in the design of new devices for communications and signal processing. Among the commonly used piezoelectric thin films, ZnO generally yields superior electromechanical properties and is expected to play a leading role in the development of SAW devices.

scholarly journals New Insights on the Zeugodacus cucurbitae (Coquillett) Bacteriome

2021 ◽  
Vol 9 (3) ◽  
pp. 659
Author(s):  
Elias Asimakis ◽  
Panagiota Stathopoulou ◽  
Apostolis Sapounas ◽  
Kanjana Khaeso ◽  
Costas Batargias ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Bacterial Communities ◽  
High Throughput Sequencing ◽  
Mutual Exclusion ◽  
Bacterial Composition ◽  
Operational Taxonomic Units ◽  
Host Diet ◽  
Dominant Bacteria ◽  
High Degree

Various factors, including the insect host, diet, and surrounding ecosystem can shape the structure of the bacterial communities of insects. We have employed next generation, high-throughput sequencing of the 16S rRNA to characterize the bacteriome of wild Zeugodacus (Bactrocera) cucurbitae (Coquillett) flies from three regions of Bangladesh. The tested populations developed distinct bacterial communities with differences in bacterial composition, suggesting that geography has an impact on the fly bacteriome. The dominant bacteria belonged to the families Enterobacteriaceae, Dysgomonadaceae and Orbaceae, with the genera Dysgonomonas, Orbus and Citrobacter showing the highest relative abundance across populations. Network analysis indicated variable interactions between operational taxonomic units (OTUs), with cases of mutual exclusion and copresence. Certain bacterial genera with high relative abundance were also characterized by a high degree of interactions. Interestingly, genera with a low relative abundance like Shimwellia, Gilliamella, and Chishuiella were among those that showed abundant interactions, suggesting that they are also important components of the bacterial community. Such knowledge could help us identify ideal wild populations for domestication in the context of the sterile insect technique or similar biotechnological methods. Further characterization of this bacterial diversity with transcriptomic and metabolic approaches, could also reveal their specific role in Z. cucurbitae physiology.

scholarly journals Genomic Tackling of Human Satellite DNA: Breaking Barriers through Time

2021 ◽  
Vol 22 (9) ◽  
pp. 4707
Author(s):  
Mariana Lopes ◽  
Sandra Louzada ◽  
Margarida Gama-Carvalho ◽  
Raquel Chaves
Keyword(s):  
Human Genome ◽  
Satellite Dna ◽  
Repetitive Sequences ◽  
Nucleotide Composition ◽  
Genomic Component ◽  
Genomic Studies ◽  
Human Genomic ◽  
Definition Of ◽  
High Degree

(Peri)centromeric repetitive sequences and, more specifically, satellite DNA (satDNA) sequences, constitute a major human genomic component. SatDNA sequences can vary on a large number of features, including nucleotide composition, complexity, and abundance. Several satDNA families have been identified and characterized in the human genome through time, albeit at different speeds. Human satDNA families present a high degree of sub-variability, leading to the definition of various subfamilies with different organization and clustered localization. Evolution of satDNA analysis has enabled the progressive characterization of satDNA features. Despite recent advances in the sequencing of centromeric arrays, comprehensive genomic studies to assess their variability are still required to provide accurate and proportional representation of satDNA (peri)centromeric/acrocentric short arm sequences. Approaches combining multiple techniques have been successfully applied and seem to be the path to follow for generating integrated knowledge in the promising field of human satDNA biology.

scholarly journals Stoichiometry and compositional plasticity of the yeast nuclear pore complex revealed by quantitative fluorescence microscopy

2018 ◽  
Vol 115 (17) ◽  
pp. E3969-E3977 ◽  
Author(s):  
Sasikumar Rajoo ◽  
Pascal Vallotton ◽  
Evgeny Onischenko ◽  
Karsten Weis
Keyword(s):  
Nuclear Pore Complex ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Altered Expression ◽  
Copy Numbers ◽  
Quantitative Image ◽  
Multiple Copies ◽  
Almost All ◽  
High Degree

The nuclear pore complex (NPC) is an eightfold symmetrical channel providing selective transport of biomolecules across the nuclear envelope. Each NPC consists of ∼30 different nuclear pore proteins (Nups) all present in multiple copies per NPC. Significant progress has recently been made in the characterization of the vertebrate NPC structure. However, because of the estimated size differences between the vertebrate and yeast NPC, it has been unclear whether the NPC architecture is conserved between species. Here, we have developed a quantitative image analysis pipeline, termed nuclear rim intensity measurement (NuRIM), to precisely determine copy numbers for almost all Nups within native NPCs of budding yeast cells. Our analysis demonstrates that the majority of yeast Nups are present at most in 16 copies per NPC. This reveals a dramatic difference to the stoichiometry determined for the human NPC, suggesting that despite a high degree of individual Nup conservation, the yeast and human NPC architecture is significantly different. Furthermore, using NuRIM, we examined the effects of mutations on NPC stoichiometry. We demonstrate for two paralog pairs of key scaffold Nups, Nup170/Nup157 and Nup192/Nup188, that their altered expression leads to significant changes in the NPC stoichiometry inducing either voids in the NPC structure or substitution of one paralog by the other. Thus, our results not only provide accurate stoichiometry information for the intact yeast NPC but also reveal an intriguing compositional plasticity of the NPC architecture, which may explain how differences in NPC composition could arise in the course of evolution.

Fabrication and characterization of highly textured (Bi,Pb)2Sr2Ca2Cu3Ox superconducting ceramics using high magnetic field and cold isostatic pressing

1995 ◽  
Vol 10 (10) ◽  
pp. 2433-2443 ◽  
Author(s):  
Wai Lo ◽  
R. Stevens ◽  
R. Doyle ◽  
A.M. Campbell ◽  
W.Y. Liang
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Cold Isostatic Pressing ◽  
Sintered Ceramic ◽  
Grain Alignment ◽  
Isostatic Pressing ◽  
Transmission Electron ◽  
Superconducting Ceramics ◽  
High Degree

High textured (Bi,Pb)2Sr2Ca2Cu3Ox ceramics have been fabricated by aligning deflocculated flakes of (Bi,Pb)2Sr2Ca2Cu3Ox suspended in an organic medium by means of a high de magnetic field (6 T) at room temperature followed by cold isostatic pressing. The proportion of the (Bi,Pb)2Sr2Ca2Cu3Ox phase in the precursor powder was carefully controlled, and the characteristics of the powder, such as size distribution and morphology, were determined. A high degree of grain alignment was found in the specimens after the magnetic alignment, although the bulk density of the materials was low. Cold isostatic pressing substantially increased the density of the magnetically prealigned specimens which also resulted in a slight decrease in the degree of grain alignment. This minor realignment was found to be due to the various kinds of processing defects that appeared in the specimens during compaction due to the grinding and cracking of the grains and their interlocking. The microstructural and superconducting properties of the sintered ceramic have been studied using texture goniometry, high resolution scanning electron microscopy, transmission electron microscopy, ac magnetic susceptometry, and critical current measurements.

scholarly journals RA3 is a reference-guided approach for epigenetic characterization of single cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shengquan Chen ◽  
Guanao Yan ◽  
Wenyu Zhang ◽  
Jinzhao Li ◽  
Rui Jiang ◽  
...  
Keyword(s):  
Single Cell ◽  
Computational Analysis ◽  
Reference Data ◽  
Single Cells ◽  
Chromatin Accessibility ◽  
Biological Variation ◽  
Superior Performance ◽  
High Dimensionality ◽  
High Degree

AbstractThe recent advancements in single-cell technologies, including single-cell chromatin accessibility sequencing (scCAS), have enabled profiling the epigenetic landscapes for thousands of individual cells. However, the characteristics of scCAS data, including high dimensionality, high degree of sparsity and high technical variation, make the computational analysis challenging. Reference-guided approaches, which utilize the information in existing datasets, may facilitate the analysis of scCAS data. Here, we present RA3 (Reference-guided Approach for the Analysis of single-cell chromatin Accessibility data), which utilizes the information in massive existing bulk chromatin accessibility and annotated scCAS data. RA3 simultaneously models (1) the shared biological variation among scCAS data and the reference data, and (2) the unique biological variation in scCAS data that identifies distinct subpopulations. We show that RA3 achieves superior performance when used on several scCAS datasets, and on references constructed using various approaches. Altogether, these analyses demonstrate the wide applicability of RA3 in analyzing scCAS data.

scholarly journals Structural differences and the presence of unsubstituted amino groups in heparan sulphates from different tissues and species

1997 ◽  
Vol 322 (2) ◽  
pp. 499-506 ◽  
Author(s):  
Toshihiko TOIDA ◽  
Hisao YOSHIDA ◽  
Hidenao TOYODA ◽  
Ichiro KOSHIISHI ◽  
Toshio IMANARI ◽  
...  
Keyword(s):  
Acid Content ◽  
Heparan Sulphate ◽  
Kidney Medulla ◽  
Isolation And Characterization ◽  
Iduronic Acid ◽  
Structural Differences ◽  
Liver And Kidney ◽  
High Degree ◽  
Different Tissues

This study presents a comparison of heparan sulphate chains isolated from various porcine and bovine tissues. 1H-NMR spectroscopy (500 MHz) was applied for structural and compositional studies on intact heparan sulphate chains. After enzymic digestion of heparan sulphate using heparin lyase I (EC 4.2.2.7) II and III (EC 4.2.2.8), the compositions of unsaturated disaccharides obtained were determined by analytical capillary electrophoresis. Correlations between the N-sulphated glucosamine residues and O-sulphation and between iduronic acid content and total sulphation were discovered using the data obtained by NMR and disaccharide analysis. Heparan sulphate chains could be classified into two groups based on the sulphation degree and the iduronic acid content. Heparan sulphate chains with a high degree of sulphation possessed also a significant number of iduronic acid residues and were isolated exclusively from porcine brain, liver and kidney medulla. The presence and amount of N-unsubstituted glucosamine residues (GlcNp) was established in all of the heparan sulphates examined. The structural context in which this residue occurs was demonstrated to be: high sulphation domain → 4)-β-d-GlcAp-(1 → 4)-α-d-GlcNp-(1 → 4)-β-d-GlcAp-(1 → low sulphation domain (where GlcNp is 2-amino-2-deoxyglucopyranose, and GlcAp is glucopyranosyluronic acid), based on the isolation and characterization of a novel, heparin lyase III-derived, GlcNp containing tetrasaccharide and hexasaccharide. The results presented suggest that structural differences may play a role in important biological events controlled by heparan sulphate in different tissues.

Characterization of SrBi2Nb2O9 Thin Films Prepared by Sol Gel Technique

1996 ◽  
Vol 459 ◽  
Author(s):  
E. Ching-Prado ◽  
W. Pérez ◽  
A. Reynés-Figueroa ◽  
R. S. Katiyar ◽  
D. Ravichandran ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Band ◽  
Sol Gel ◽  
Orthorhombic Symmetry ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Gel Technique ◽  
High Degree ◽  
First Time

ABSTRACTThin films of SrBi2Nb2O9 (SBN) with thicknesses of 0.1, 0.2, and 0.4 μ were grown by Sol-gel technique on silicon, and annealed at 650°C. The SBN films were investigated by Raman scatering for the first time. Raman spectra in some of the samples present bands around 60, 167, 196, 222, 302, 451, 560, 771, 837, and 863 cm−1, which correspond to the SBN formation. The study indicates that the films are inhomogeneous, and only in samples with thicknesses 0.4 μ the SBN material was found in some places. The prominent Raman band around 870 cm−1, which is the A1g mode of the orthorhombic symmetry, is assigned to the symmetric stretching of the NbO6 octahedrals. The frequency of this band is found to shift in different places in the same sample, as well as from sample to sample. The frequency shifts and the width of the Raman bands are discussed in term of ions in non-equilibrium positions. FT-IR spectra reveal a sharp peak at 1260 cm−1, and two broad bands around 995 and 772 cm−1. The bandwidths of the latter two bands are believed to be associated with the presence of a high degree of defects in the films. The experimental results of the SBN films are compared with those obtained in SBT (T=Ta) films. X-ray diffraction and SEM techniques are also used for the structural characterization.

Einbringen von Gewinden in SLM-Bauteile*/Insertion of threads into SLM components – Reliable strategy for inserting threads into additively manufactured components

2019 ◽  
Vol 109 (01-02) ◽  
pp. 24-29
Author(s):  
E. Abele ◽  
T. Scherer ◽  
F. Geßner ◽  
M. Weigold
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Downstream Processing ◽  
Manufacturing Processes ◽  
Laser Melting ◽  
Manufacturing Costs ◽  
Process Reliability ◽  
High Degree ◽  
Design Freedom ◽  
Processing Steps

Additive Fertigungsverfahren zeichnen sich durch große Gestaltungsfreiheit aus, welche die Herstellung komplexer Bauteile ermöglicht. Angesichts hoher Fertigungskosten ist die Prozesssicherheit nachgeordneter Bearbeitungsschritte (wie zum Beispiel die Gewindefertigung) von großer Bedeutung. Der Artikel stellt die Ergebnisse einer Untersuchungsreihe vor, die unterschiedliche Ansätze der Gewindefertigung in Bauteilen aus Stahl behandelt, die mittels Selektivem Laserschmelzverfahren gefertigt wurden.   Additive manufacturing processes are characterized by a high degree of design freedom to enablet the production of complex components. To reduce manufacturing costs, the process reliability of downstream processing steps (e. g. thread production) is of great importance. This article presents the results of a series of investigations dealing with different approaches to thread production in steel components manufactured by selective laser melting

scholarly journals Influence of Bio-Oil Phospholipid on the Hydrodeoxygenation Activity of NiMoS/Al2O3 Catalyst

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 418 ◽  
Author(s):  
Muhammad Abdus Salam ◽  
Derek Creaser ◽  
Prakhar Arora ◽  
Stefanie Tamm ◽  
Eva Lind Grennfelt ◽  
...  
Keyword(s):  
Active Sites ◽  
Batch Reactor ◽  
Active Phase ◽  
Aluminum Phosphate ◽  
Spent Catalyst ◽  
Bio Oil ◽  
Pore Blockage ◽  
Sulfided Catalyst ◽  
High Degree

Hydrodeoxygenation (HDO) activity of a typical hydrotreating catalyst, sulfided NiMo/γ-Al2O3 for deoxygenation of a fatty acid has been explored in a batch reactor at 54 bar and 320 °C in the presence of contaminants, like phospholipids, which are known to be present in renewable feeds. Oleic acid was used for the investigation. Freshly sulfided catalyst showed a high degree of deoxygenation activity; products were predominantly composed of alkanes (C17 and C18). Experiments with a major phospholipid showed that activity for C17 was greatly reduced while activity to C18 was not altered significantly in the studied conditions. Characterization of the spent catalyst revealed the formation of aluminum phosphate (AlPO4), which affects the active phase dispersion, blocks the active sites, and causes pore blockage. In addition, choline, formed from the decomposition of phospholipid, partially contributes to the observed deactivation. Furthermore, a direct correlation was observed in the accumulation of coke on the catalyst and the amount of phospholipid introduced in the feed. We therefore propose that the reason for the increased deactivation is due to the dual effects of an irreversible change in phase to aluminum phosphate and the formation of choline.

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