We discuss the isostatic adjustment of the earth in response to Pleistocene deglaciation, and derive constraints on the earth's viscosity profile. We model the earth as viscoelastic, ...self-gravitating, realistically stratified and spherically symmetric. It is shown that the earth's relaxation eigenspectrum, besides possessing a small set of well-known discrete modes, also includes infinitely dense sets of modes (a continuous spectrum) which separate into classes that depend on the principal restoring force of the mode. Methods for estimating the continuous spectrum are discussed, and the effects on the predicted uplift are assessed. We find that the effects of the continuous spectrum are far less important than those of the discrete modes, though the presence of the continuous spectrum can make the discrete modes more difficult to identify. The continuous spectrum does become important when computing the rebound due to more recent loading, such as might be associated with present-day changes in polar ice. We use our model to refine predictions of the earth's response to Pleistocene glacial loading, with particular emphasis on implications for mantle viscosity. We have used time histories that are consistent with the recently recalibrated 14C time-scale. A special effort is made to match the geologic records of sea-level at sites in the vicinity of Hudson Bay. We find, consistent with the results of other authors, that the curvatures of the records are sensitive indicators of lower-mantle viscosity, but that there are inconsistencies between the records at different sites. However, we find we are also able to change the predicted curvatures by modifying the temporal and spatial distribution of the ice loads. If we assume a factor of 50 increase in viscosity between the upper and lower mantles, and if we assume that the ice on the eastern side of Hudson Bay melted a few thousand years later than the ice on the western side (a result consistent with recent geologic evidence), we are able to match the observed sea-level data about as well as we are able to, if we use, instead, a uniform mantle viscosity profile. A model with a factor of 50 jump in viscosity predicts a large free-air gravity anomaly over northern Canada that is reasonably consistent with what is observed, whereas a uniform viscosity model does not (though some authors have argued that the observed North American gravity anomaly may be mostly a consequence of mantle convection, and largely unrelated to postglacial rebound). Our objective here is not to present a preferred ice model or viscosity profile. Rather, we conclude only that the interpretation of the data is ambiguous, and that the mantle viscosity profile can not yet be uniquely inferred from them.
This paper presents a preliminary analysis of the possibility of using post-glacial rebound observations to place constraints on the anisotropy of upper-mantle viscosity. We extend existing analyses ...by considering a visco-elastic, spherical, self-gravitating Earth. We show that three independent viscosity parameters are required to describe a Maxwell solid with transversely isotropic viscosity and isotropic elasticity. We develop a theoretical formalism for including the effects of transversely isotropic visco-elasticity in post-glacial rebound models. Using this formalism to describe anisotropy in the upper mantle, we model the free air gravity anomaly, relative sea-level changes, and present-day horizontal motion caused by the rebound, to assess their dependence on the upper-mantle viscosity parameters. We find that as long as those parameters are no larger than the lower-mantle (isotropic) viscosity, the results for the gravity and sea-level changes are notably sensitive to only one of the three viscosity parameters. This suggests, at least for the case where the lower-mantle viscosity is significantly larger than the upper-mantle viscosity, that post-glacial rebound studies of gravity and sea-level will be hard pressed to usefully constrain viscous anisotropy. We do find that the horizontal motion is relatively sensitive to transverse isotropy and so might be used, in principle, to constrain the anisotropy. In practice, though, it is likely that the strong dependence of horizontal motion on details of the ice model, coupled with the uncertainties in existing ice models, would make such attempts impractical.
Changes in polar ice could cause vertical crustal motion of up to several mm yr-1 along the edge of the Greenland and Antarctic ice caps. Measurements of the uplift could help constrain the changing ...ice volumes. The problem is complicated by the Earth's visco-elastic response to past loading, including the Late Pleistocene deglaciation. A method is described for removing these visco-elastic effects, by using simultaneous measurements of vertical motion and surface gravity. A linear combination of these two measurement types can be formed which is relatively independent of visco-elastic effects, and which can be interpreted in terms of present-day fluctuations in ice.PUBLICATION ABSTRACT
This thesis discusses the isostatic adjustment of the earth in response to Pleistocene glaciation and deglaciation, and derives constraints on the earth's viscosity profile. The earth is modeled as ...visco-elastic, self-gravitating, realistically stratified, and spherically-symmetric. It is shown that the earth's relaxation eigenspectrum, besides possessing a small set of well known discrete modes, also includes infinitely dense sets of modes (a continuous spectrum). Methods for estimating the continuous spectrum are discussed, and its effects on the predicted uplift are assessed. We use our model to refine predictions of the earth's response to Pleistocene glacial loading, with particular emphasis on implications for mantle viscosity. A special effort is made to match both the geologic record of sea level at sites in the vicinity of Hudson Bay, and the observed free air gravity anomaly over northern Canada. We find that by modifying the ice model we are able to resolve the inconsistencies between the gravity and sea level data and to fit all of these data simultaneously, provided we assume the lower mantle viscosity is much larger than the viscosity of the upper mantle. The objective of this thesis is not to present a preferred ice model or viscosity profile. Rather, we conclude only that the data do not rule out the possibility of a large contrast in viscosity across the 670-km boundary. This thesis also makes a preliminary effort to explore the anisotropy of mantle viscosity. We extend the study of anisotropy of mantle rheology to a visco-elastic, spherically-symmetric, self-gravitating, realistically stratified earth. We model the mantle as a transversely isotropic Maxwell solid, with isotropic elastic parameters and transversely isotropic viscosity. We construct a mathematical formalism to describe the loading of such an earth, and develop a numerical method to solve the equations. It requires three viscous parameters to fully represent the anisotropy. We find that the earth's response to the ice load of the last ice age depends dominantly on only one of the parameters, which is referred to as the shear viscosity: the viscosity parameter associated with horizontal flow in the isotropic plane. We conclude that post glacial rebound can not effectively discriminate between isotropic and transversely isotropic rheologies.
<正>Objective:To identify full length cDNA sequence of lactate dehydrogenase(LDH) from adult Echinococcus granulosus(E.granulosus) and to predict the structure and function of its encoding ...protein using bioinformatics methods.Methods:With the help of NCBI,EMBI, Expasy and other online sites,the open reading frame(ORF),conserved domain,physical and chemical parameters,signal peptide,epitope,topological structures of the protein sequences were predicted and a homology tertiary structure model was created:Vector NT1 software was used for sequence alignment,phylogenetic tree construction and tertiary structure prediction. Results:The target sequence was 1 233 bp length with a 996 bp biggest ORF encoding 331 amino acids protein with typical L-LDH conserved domain.It was confirmed as full length cDNA of LDH from E.granulosus and named as EgLDH(GenBank accession number:HM748917).The predicted molecular weight and isoelectric point of the deduced protein were 3 5516.2Da and 6.32 respectively.Compared with LDHs from Taenia solium,Taenia saginata asiatica,Spirometra erinaceieuropaei.Schistosoma japonicum,Clonorchis sinensis and human,it showed similarity of 86% ,85% ,55% ,58% ,58% and 53% ,respectively.EgLDH contained 3 putative transmembrane regions and 4 major epitopes(54aa-59aa.81aa-87aa,97aa-102aa,307aa-313aa),the latter were significant different from the corresponding regions of human LDH.In addition,some NAD and substrate binding sites located on epitopes 54aa-59aa and 97aa-102aa,respectively.Tertiary structure prediction showed that 3 key catalytic residues 105R,165D and 192H forming a catalytic center near the epitope 97aa-102aa,most NAD and substrate binding sites located around the center.Conclusions:The full length cDNA sequences of EgLDH were identified.It encoded a putative transmembrane protein which might be an ideal target molecule for vaccine and drugs.
Soil samples were collected with distance at 5, 20, 40, 80, 160, and 320 m from the Shen-Ha （Shenyang-Harbin） Highway, Northeast China, to investigate the effect of heavy metals of highway origin on ...soil nematode guilds. The contents of soil Pb, Cu, Zn, and the nematode community structure were analyzed. The results showed that the contents of total and available Pb, Ca, Zn varied significantly with the different distances from the highway. Pb was the main pollutant in the soils in the vicinity of Shen-Ha Highway. The zone from 20 to 40 m away from the highway was the most polluted area. The highest abundance of soil nematodes was found at 5 m while the lowest at 20 m away from the highway. Thirty six genera of nematodes belonging to 23 families were identified. Nematode guilds having different responses to soil heavy metals were classified into four types. Soil nematode guilds may act as a prominent indicator to heavy metal pollution of highway origin.
Cys2His2-like fold group (C2H2)-type zinc finger proteins promote root hair growth and development by regulating their target genes. However, little is known about their potential negative roles in ...root hair initiation and elongation. Here, we show that the C2H2-type zinc finger protein named ZINC FINGER PROTEIN1 (AtZP1), which contains an ERF-associated amphiphilic repression (EAR) motif, negatively regulates Arabidopsis (
) root hair initiation and elongation. Our results demonstrate that
is highly expressed in root hairs and that AtZP1 inhibits transcriptional activity during root hair development. Plants overexpressing
lacked root hairs, while loss-of-function mutants had longer and more numerous root hairs than the wild type. Transcriptome analysis indicated that AtZP1 downregulates genes encoding basic helix-loop-helix (bHLH) transcription factors associated with root hair cell differentiation and elongation. Mutation or deletion of the EAR motif substantially reduced the inhibitory activity of AtZP1. Chromatin immunoprecipitation assays,
:glucocorticoid receptor (GR) induction experiments, electrophoretic mobility shift assays, and yeast one-hybrid assays showed that AtZP1 directly targets the promoters of bHLH transcription factor genes, including the key root hair initiation gene ROOT HAIR DEFECTIVE6 (
) and root hair elongation genes ROOT HAIR DEFECTIVE 6-LIKE 2 (
) and
, and suppresses root hair development. Our findings suggest that
functions downstream of
and negatively regulates root hair initiation and elongation, by suppressing
,
, and
transcription via the GL2/ZP1/RSL pathway.
This study evaluated cardiac involvement in patients recovered from coronavirus disease-2019 (COVID-19) using cardiac magnetic resonance (CMR).
Myocardial injury caused by COVID-19 was previously ...reported in hospitalized patients. It is unknown if there is sustained cardiac involvement after patients’ recovery from COVID-19.
Twenty-six patients recovered from COVID-19 who reported cardiac symptoms and underwent CMR examinations were retrospectively included. CMR protocols consisted of conventional sequences (cine, T2-weighted imaging, and late gadolinium enhancement LGE) and quantitative mapping sequences (T1, T2, and extracellular volume ECV mapping). Edema ratio and LGE were assessed in post–COVID-19 patients. Cardiac function, native T1/T2, and ECV were quantitatively evaluated and compared with controls.
Fifteen patients (58%) had abnormal CMR findings on conventional CMR sequences: myocardial edema was found in 14 (54%) patients and LGE was found in 8 (31%) patients. Decreased right ventricle functional parameters including ejection fraction, cardiac index, and stroke volume/body surface area were found in patients with positive conventional CMR findings. Using quantitative mapping, global native T1, T2, and ECV were all found to be significantly elevated in patients with positive conventional CMR findings, compared with patients without positive findings and controls (median interquartile range: native T1 1,271 ms 1,243 to 1,298 ms vs. 1,237 ms 1,216 to 1,262 ms vs. 1,224 ms 1,217 to 1,245 ms; mean ± SD: T2 42.7 ± 3.1 ms vs. 38.1 ms ± 2.4 vs. 39.1 ms ± 3.1; median interquartile range: 28.2% 24.8% to 36.2% vs. 24.8% 23.1% to 25.4% vs. 23.7% 22.2% to 25.2%; p = 0.002; p < 0.001, and p = 0.002, respectively).
Cardiac involvement was found in a proportion of patients recovered from COVID-19. CMR manifestation included myocardial edema, fibrosis, and impaired right ventricle function. Attention should be paid to the possible myocardial involvement in patients recovered from COVID-19 with cardiac symptoms.
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One RIL population derived from the cross between Dalibao and BYL8 was used to examine the phenotypes of kernel-related traits in four different environments. Six important kernel traits, kernel ...length (KL), kernel width (KW), kernel perimeter (KP), kernel area (KA), kernel length/width ratio (KLW), and thousand-kernel weight (TKW) were evaluated in Yangling, Shaanxi Province, China (2016 and 2017), Nanyang, Henan Province, China (2017) and Suqian, Jiangsu Province, China (2017). A genetic linkage map was constructed using 205 SSR markers, and a total of 21 significant QTLs for KL, KW, KP, KA, KLW and TKW were located on 10 of the 21 wheat chromosomes, including 1A, 1B, 2A, 2B, 2D, 3D, 4D, 5A, 5B, and 7D, with a single QTL in different environments explaining 3.495-30.130% of the phenotypic variation. There were four loci for KLW, five for KA, five for KL, three for KP, two for KW, and two for TKW among the detected QTLs. We used BSA + 660 K gene chip technology to reveal the positions of major novel QTLs for KLW. A total of 670 out of 5285 polymorphic SNPs were detected on chromosome 2A. The SNPs in 2A are most likely related to the major QTL, and there may be minor QTLs on 5B, 7A, 3A and 4B. SSR markers were developed to verify the chromosome region associated with KLW. A linkage map was constructed with 7 SSR markers, and a major effect QTL was identified within a 21.55 cM interval, corresponding to a physical interval of 10.8 Mb in the Chinese Spring RefSeq v1.0 sequence. This study can provide useful information for subsequent construction of fine mapping and marker-assisted selection breeding.
Heavy metal cadmium (Cd) is a common environmental pollutant in soils, which has an negative impacts on crop growth and development. At present, cadmium has become a major soil and water heavy metal ...pollutant, which not only causes permanent and irreversible health problems for humans, but also causes a significant reduction in crop yields.
This study examined the chemical forms of Cd in the roots of two wheat varieties (M1019 and Xinong20) by continuous extraction and analyzed differences in distribution characteristics of Cd in the root cell wall, cytoplasm, and organelles by elemental content determination and subcellular separation. Furthermore, we conducted proteomics analysis of the roots of the two varieties under Cd pollution using mass spectrometry quantitative proteomics techniques. A total of 11,651 proteins were identified, of which 10,532 proteins contained quantitative information. In addition, the differentially expressed proteins in the two varieties were related to DNA replication and repair, protein metabolism, and the glutathione metabolism pathway.
The results of this study improve our understanding of the mechanism of plant responses to Cd stress.
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