Conditional Modulation of Biological Processes by Low-Temperature Degrons

2017 ◽  
pp. 407-416 ◽  
Author(s):  
Nico Dissmeyer
Keyword(s):  
Low Temperature ◽  
Biological Processes

scholarly journals Structures of a human blood group glycosyltransferase in complex with a photo-activatable UDP-Gal derivative reveal two different binding conformations

2014 ◽  
Vol 70 (8) ◽  
pp. 1015-1021 ◽  
Author(s):  
René Jørgensen ◽  
Gaëlle Batot ◽  
Karin Mannerstedt ◽  
Anne Imberty ◽  
Christelle Breton ◽  
...  
Keyword(s):  
Low Temperature ◽  
Blood Group ◽  
Human Blood ◽  
Active Site ◽  
Biological Processes ◽  
Dynamic Nature ◽  
Reaction Intermediate ◽  
Dual Specificity ◽  
Intermediate States ◽  
Sequential Addition

Glycosyltransferases (GTs) catalyse the sequential addition of monosaccharides to specific acceptor molecules and play major roles in key biological processes. GTs are classified into two main families depending on the inverted or retained stereochemistry of the glycosidic bond formed during the reaction. While the mechanism of inverting enzymes is well characterized, the precise nature of retaining GTs is still a matter of much debate. In an attempt to clarify this issue, studies were initiated to identify reaction-intermediate states by using a crystallographic approach based on caged substrates. In this paper, two distinct structures of AA(Gly)B, a dual-specificity blood group synthase, are described in complex with a UDP-galactose derivative in which the O6′′ atom is protected by a 2-nitrobenzyl group. The distinct conformations of the caged substrate in both structures of the enzyme illustrate the highly dynamic nature of its active site. An attempt was also made to photolyse the caged compound at low temperature, which unfortunately is not possible without damaging the uracil group as well. These results pave the way for kinetic crystallography experiments aiming at trapping and characterizing reaction-intermediate states in the mechanism of enzymatic glycosyl transfer.

scholarly journals Transcriptome-wide identification of MAPKKK genes in bermudagrass (Cynodon dactylon L.) and their potential roles in low temperature stress responses

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10159
Author(s):  
Wei Wang ◽  
An Shao ◽  
Erick Amombo ◽  
Shugao Fan ◽  
Xiao Xu ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Low Temperature ◽  
Gene Family ◽  
Temperature Stress ◽  
Stress Responses ◽  
Cynodon Dactylon ◽  
Diploid Species ◽  
Low Temperature Stress ◽  
Biological Processes ◽  
Mapk Cascades

As upstream components of MAPK cascades, mitogen-activated protein kinase kinase kinases (MAPKKKs) act as adaptors linking upstream signaling steps to the core MAPK cascades. MAPK cascades are universal modules of signal transduction in eukaryotic organisms and play crucial roles in plant development processes and in responses to biotic and abiotic stress and signal transduction. Members of the MAPKKK gene family have been identified in several plants,however, MAPKKKs have not been systematically studied in bermudagrass (Cynodon dactylon L.). In this study, 55 potential CdMAPKKKs were produced from bermudagrass transcriptome data, of which 13 belonged to the MEKK, 38 to the Raf, and 4 to the ZIK subfamily. Multiple alignment and conserved motif analysis of CdMAPKKKs supported the evolutionary relationships inferred from phylogenetic analyses. Moreover, the distribution pattern in Poaceae species indicated that members of the MAPKKK family were conserved among almost all diploid species, and species-specific polyploidy or higher duplication ratios resulted in an expansion of the MAPKKK family. In addition, 714 co-functional links which were significantly enriched in signal transduction, responses to temperature stimuli, and other important biological processes of 55 CdMAPKKKs were identified using co-functional gene networks analysis; 30 and 19 co-functional genes involved in response to cold or heat stress, respectively, were also identified. Results of promoter analyses, and interaction network investigation of all CdMAPKKKs based on the rice homologs suggested that CdMAPKKKs are commonly associated with regulation of numerous biological processes. Furthermore, 12 and 13 CdMAPKKKs were significantly up- and downregulated, respectively, in response to low temperature stress; among them, six CdMAPKKKs were significantly induced by low temperature stress, at least at one point in time. This is the first study to conduct identification and functional analysis of the MAPKKK gene family in bermudagrass, and our results provide a foundation for further research on the functions of CdMAPKKKs in response to low temperature stress.

Comparative Transcriptome Analysis Between Cold-Tolerant and Sensitive Brassica Oleracea L. in Response to Low Temperature Stress

2021 ◽  
Author(s):  
Shuhan Jiang ◽  
Dongjian Xia ◽  
Qian Dai ◽  
Yuxia Luo ◽  
Yao Chen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Low Temperature ◽  
Brassica Oleracea ◽  
Cold Tolerance ◽  
Temperature Stress ◽  
Transcriptome Analysis ◽  
Low Temperature Stress ◽  
Biological Processes ◽  
The Common ◽  
Go Terms

Abstract Background: Brassica oleracea L. occupies an important position in the annual production of vegetables. But during winter Brassica oleracea L. often suffers from low temperatures and even sub-zero temperatures. Through transcriptome analysis and identification, the pathways involved in cold tolerance of Brassica oleracea L. were analyzed and candidate genes related to cold tolerance of Brassica oleracea L. were identified.Results: Under low temperature stress, a large number of significantly different genes were found in Zhonggan1229 (ZG, low temperature tolerance) and Yingchun (YN, low temperature sensitive). There were 3902 significantly up-regulated genes and 5309 significantly down-regulated genes in ZG, and 4253 significantly up-regulated genes and 5938 significantly down-regulated genes in YN. Among them, 1844 different genes are the specific different genes in ZG and 6089 genes are the common different genes to response the low temperature stress. By annotating the specific different genes in ZG, 26 of the top 30 enriched GO terms belonged to biological processes, 4 terms belonged to molecular functions. By annotating the common different genes, 23 GO terms belonged to biological processes, 1 GO term belonged to molecular functions, and 6 GO terms belonged to cellular components. Circadian rhythms of plants and Plant hormone signal transduction were not only significantly enriched in the two analyzed genes, but also the effects of low temperature stress were most significant. Among the unique different genes in ZG, 154 genes were annotated into transcription factor families, and 79 genes were up-regulated and 75 genes were down-regulated, the encoding of MYB-related proteins was the largest group. Among the different genes shared by the two varieties, 516 genes were annotated into corresponding transcription factor families, 211 genes were up-regulated and 296 genes were down-regulated, however, there were 4 genes that were up-regulated in ZG but down-regulated in YN, and 5 genes that were down-regulated in ZG but up-regulated in YN, the largest group was the protein encoding ERF.Conclusions: The results identified important genes, pathways, and transcription factors that respond to low temperature stress, provided cold tolerance gene resources for the subsequent cold tolerance breeding research of Brassica oleracea L..

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

High-Vacuum Evaporation and a Cryostage to Observe Fractured Yeast

1988 ◽  
Vol 46 ◽  
pp. 256-257
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Eugene L. Vigil
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Standard Specimen ◽  
High Vacuum ◽  
Specimen Holder ◽  
Sputter Coating ◽  
Fresh Frozen ◽  
Gain Access ◽  
Scanning Electron ◽  
Transfer Device

Investigators have long realized the potential advantages of using a low temperature (LT) stage to examine fresh, frozen specimens in a scanning electron microscope (SEM). However, long working distances (W.D.), thick sputter coatings and surface contamination have prevented LTSEM from achieving results comparable to those from TEM freeze etch. To improve results, we recently modified techniques that involve a Hitachi S570 SEM, an Emscope SP2000 Sputter Cryo System and a Denton freeze etch unit. Because investigators have frequently utilized the fractured E face of the plasmalemma of yeast, this tissue was selected as a standard for comparison in the present study.In place of a standard specimen holder, a modified rivet was used to achieve a shorter W.D. (1 to -2 mm) and to gain access to the upper detector. However, the additional height afforded by the rivet, precluded use of the standard shroud on the Emscope specimen transfer device. Consequently, the sample became heavily contaminated (Fig. 1). A removable shroud was devised and used to reduce contamination (Fig. 2), but the specimen lacked clean fractured edges. This result suggested that low vacuum sputter coating was also limiting resolution.

Observation by HVEM of the martensite transformation and the superconducting transition in Nb3Sn

1988 ◽  
Vol 46 ◽  
pp. 788-789
Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Superconducting State ◽  
Martensite Transformation ◽  
Sputter Deposition ◽  
Diffusion Reaction ◽  
Solute Diffusion ◽  
Superconducting Transition ◽  
Twin Boundaries ◽  
Martensite Structure

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

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