On the physical settings of ice bridge formation in Nares Strait

2021 ◽  
Author(s):  
S. Kirillov ◽  
D. G. Babb ◽  
A. S. Komarov ◽  
I. Dmitrenko ◽  
J. K. Ehn ◽  
...  
Keyword(s):  
Bridge Formation ◽  
Nares Strait

Introductory Remarks

1980 ◽  
Vol 38 ◽  
pp. 598-599
Author(s):  
H. Mohri
Keyword(s):  
Muscle Contraction ◽  
Experimental Evidence ◽  
Sea Urchin ◽  
Constant Length ◽  
Thin Filaments ◽  
Bridge Formation ◽  
Thick Filaments ◽  
Sliding Mechanism ◽  
Radial Spokes ◽  
Cilia And Flagella

In 1959, Afzelius observed the presence of two rows of arms projecting from each outer doublet microtubule of the so-called 9 + 2 pattern of cilia and flagella, and suggested a possibility that the outer doublet microtubules slide with respect to each other with the aid of these arms during ciliary and flagellar movement. The identification of the arms as an ATPase, dynein, by Gibbons (1963)strengthened this hypothesis, since the ATPase-bearing heads of myosin molecules projecting from the thick filaments pull the thin filaments by cross-bridge formation during muscle contraction. The first experimental evidence for the sliding mechanism in cilia and flagella was obtained by examining the tip patterns of molluscan gill cilia by Satir (1965) who observed constant length of the microtubules during ciliary bending. Further evidence for the sliding-tubule mechanism was given by Summers and Gibbons (1971), using trypsin-treated axonemal fragments of sea urchin spermatozoa. Upon the addition of ATP, the outer doublets telescoped out from these fragments and the total length reached up to seven or more times that of the original fragment. Thus, the arms on a certain doublet microtubule can walk along the adjacent doublet when the doublet microtubules are disconnected by digestion of the interdoublet links which connect them with each other, or the radial spokes which connect them with the central pair-central sheath complex as illustrated in Fig. 1. On the basis of these pioneer works, the sliding-tubule mechanism has been established as one of the basic mechanisms for ciliary and flagellar movement.

Explanatory notes to the Geological map of Greenland, 1:500 000, Humboldt Gletscher, Sheet 6

2004 ◽  
pp. 1-48
Author(s):  
Peter R. Dawes
Keyword(s):  
Coarse Grained ◽  
Mobile Belt ◽  
Nares Strait ◽  
General Terms ◽  
Mineral Occurrence ◽  
North Eastern ◽  
Copper Gold ◽  
High Grade Metamorphism ◽  
Geological Map ◽  
Map Series

NOTE: This Map Description was published in a former series of GEUS Bulletin. Please use the original series name when citing this series, for example: Dawes, P. R. (2004). Explanatory notes to the Geological map of Greenland, 1:500 000, Humboldt Gletscher, Sheet 6. Geological Survey of Denmark and Greenland Map Series 1, 48 pp. + map. https://doi.org/10.34194/geusm.v1.4615  _______________ These explanatory notes cover the map region bounded by latitudes 78°N and 81°N and longitudes 56°W and 74°W, with geology shown on the land areas between Nares Strait - the seaway between Greenland and Ellesmere Island, Canada - and the Inland Ice. The bedrock geology is composed of Precambrian and Lower Palaeozoic provinces that continue across Nares Strait into Canada. Map units and mineral occurrences are described in general terms and are proceeded by sections on physical environment, logistics, data sources and geoscientific research. The notes are aimed at the practical user and a guide for further reading. The bedrock is composed of three provinces separated by unconformities, each representing a hiatus of c. 500 Ma during which basic dykes were emplaced. The Palaeoproterozoic Inglefield mobile belt, forming the crystalline shield, is an E-W-trending belt of deposition and orogeny characterised by polyphase magmatism, deformation and high-grade metamorphism. Clastic deposition, with magmatism at c. 1985 Ma, are the oldest events recorded, followed by the accumulation of the Etah Group (carbonate, pelitic and psammitic sediments with supposedly coeval mafic and ultramafic rocks) between 1980 and 1950 Ma ago. These rocks were intruded 1950 to 1915 Ma ago by the Etah meta-igneous complex, that records polyphase plutonism (intermediate to felsic, with some basic and magnetite-rich rocks), followed by deformation and partial melting producing granites 1785 to 1740 Ma ago. The Mesoproterozoic Thule Basin, defined by the unmetamorphosed and little deformed Thule Supergroup, records sedimentation and basaltic volcanism at least as old as 1270 Ma. The faulted, north-eastern basin margin shown on the map preserves the passage from the basinal sequence to a relatively thin platform succession invaded by basic sills. The Palaeozoic Franklinian Basin is represented by a homoclinal Cambrian to Silurian shelf carbonate succession and a major Silurian reef complex, with coeval siliciclastic slope deposits. The map region includes the classical area for Franklinian stratigraphy, now composed of 29 formations and four groups - Ryder Gletscher, Morris Bugt, Washington Land and Peary Land Groups. The only younger units preserved in the map region are widespread Quaternary deposits, an isolated outcrop of coarse-grained fluvial deposits (Bjørnehiet Formation) and non-carbonised wood erratics of Neogene age. Five mineral occurrence types are shown on the map: in lithologies of the Inglefield mobile belt, sulphide-graphite rust zones, a magnetite deposit and copper-gold mineralisation and in the Franklinian Basin, commercially drilled, zinc-lead-silver and zinc-lead-barium mineralisations. The basic ingredients of a petroleum model exist in the Franklinian Basin but prospectivity is low.

USING A PRECAMBRIAN TERRANE BOUNDARY TO ESTIMATE SLIP ON THE WEGENER FAULT, NARES STRAIT

2017 ◽  
Author(s):  
Jane A. Gilotti ◽  
◽  
William C. McClelland ◽  
Karsten Piepjohn ◽  
Werner von Gosen
Keyword(s):  
Nares Strait

DEGLACIATION OF NARES STRAIT AND WASHINGTON LAND, NORTHWEST GREENLAND

2017 ◽  
Author(s):  
Elizabeth G. Ceperley ◽  
◽  
Shaun A. Marcott ◽  
Melissa M. Reusche ◽  
Aaron M. Barth ◽  
...  
Keyword(s):  
Nares Strait

scholarly journals Influence of pH, Temperature and Protease Inhibitors on Kinetics and Mechanism of Thermally Induced Aggregation of Potato Proteins

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 796
Author(s):  
David J. Andlinger ◽  
Pauline Röscheisen ◽  
Claudia Hengst ◽  
Ulrich Kulozik
Keyword(s):  
Protein Interactions ◽  
Disulfide Bonds ◽  
Food Systems ◽  
Disulfide Bridge ◽  
Food Protein ◽  
Potato Protein ◽  
Covalent Bonds ◽  
Bridge Formation ◽  
Induced Aggregation ◽  
Influence Of Ph

Understanding aggregation in food protein systems is essential to control processes ranging from the stabilization of colloidal dispersions to the formation of macroscopic gels. Patatin rich potato protein isolates (PPI) have promising techno-functionality as alternatives to established proteins from egg white or milk. In this work, the influence of pH and temperature on the kinetics of PPI denaturation and aggregation was investigated as an option for targeted functionalization. At a slightly acidic pH, rates of denaturation and aggregation of the globular patatin in PPI were fast. These aggregates were shown to possess a low amount of disulfide bonds and a high amount of exposed hydrophobic amino acids (S0). Gradually increasing the pH slowed down the rate of denaturation and aggregation and alkaline pH levels led to an increased formation of disulfide bonds within these aggregates, whereas S0 was reduced. Aggregation below denaturation temperature (Td) favored aggregation driven by disulfide bridge formation. Aggregation above Td led to fast unfolding, and initial aggregation was less determined by disulfide bridge formation. Inter-molecular disulfide formation occurred during extended heating times. Blocking different protein interactions revealed that the formation of disulfide bond linked aggregation is preceded by the formation of non-covalent bonds. Overall, the results help to control the kinetics, morphology, and interactions of potato protein aggregation for potential applications in food systems.

scholarly journals Piper nigrum CYP719A37 Catalyzes the Decisive Methylenedioxy Bridge Formation in Piperine Biosynthesis

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 128
Author(s):  
Arianne Schnabel ◽  
Fernando Cotinguiba ◽  
Benedikt Athmer ◽  
Thomas Vogt
Keyword(s):  
Ferulic Acid ◽  
Functional Expression ◽  
Black Pepper ◽  
Amide Bond ◽  
Chain Elongation ◽  
Piper Nigrum ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bridge Formation ◽  
Phylogenetic Origin ◽  
Catalyzed Reactions

Black pepper (Piper nigrum) is among the world’s most popular spices. Its pungent principle, piperine, has already been identified 200 years ago, yet the biosynthesis of piperine in black pepper remains largely enigmatic. In this report we analyzed the characteristic methylenedioxy bridge formation of the aromatic part of piperine by a combination of RNA-sequencing, functional expression in yeast, and LC-MS based analysis of substrate and product profiles. We identified a single cytochrome P450 transcript, specifically expressed in black pepper immature fruits. The corresponding gene was functionally expressed in yeast (Saccharomyces cerevisiae) and characterized for substrate specificity with a series of putative aromatic precursors with an aromatic vanilloid structure. Methylenedioxy bridge formation was only detected when feruperic acid (5-(4-hydroxy-3-methoxyphenyl)-2,4-pentadienoic acid) was used as a substrate, and the corresponding product was identified as piperic acid. Two alternative precursors, ferulic acid and feruperine, were not accepted. Our data provide experimental evidence that formation of the piperine methylenedioxy bridge takes place in young black pepper fruits after a currently hypothetical chain elongation of ferulic acid and before the formation of the amide bond. The partially characterized enzyme was classified as CYP719A37 and is discussed in terms of specificity, storage, and phylogenetic origin of CYP719 catalyzed reactions in magnoliids and eudicots.

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