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61.
Na,K-ATPase in several tissues of the rat: Tissue-specific expression of subunit mRNAs and enzyme activity 总被引:4,自引:0,他引:4
Gregory G. Gick Mary Ann Hatala David Chon Faramarz Ismail-Beigi 《The Journal of membrane biology》1993,131(3):229-236
Summary The relative contents of Na,K-ATPase subunit mRNAs in rat renal cortex; ventricular myocardium, skeletal muscle (hind limb), liver and brain (cerebrum) were measured. Expressed per unit DNA, mRNA1 content was 2-fold greater in the kidney and brain as compared to either heart, skeletal muscle or liver. The hierarchy of mRNA2 expression was brain > skeletal muscle > heart, whereas mRNA3 was restricted to brain. Betal subunit mRNA content in both kidney and brain exceeded the abundance of liver mRNA
1 by 7-fold. In all tissues examined, the combined abundances of the alpha subunit mRNAs exceeded the content of mRNA
1 The hierarchy of Na,K-ATPase activity expressed per unit. DNA was brain > kidney > skeletal muscle = heart > liver. The sum of mRNA as well as mRNA
1 content, expressed per g of tissue, was highest in brain and kidney. A statistically significant correlation between mRNA
1 content and Na,K-ATPase activity was evident. 相似文献
62.
1. The enzymatic steps of the CO2 fixation cycle responsible for the overall inhibition of CO2 fixation caused by the lowering of the Mg2+ concentration in the stroma were investigated. For this the Mg2+ concentration in the stroma was decreased by addition of the ionophore A 23187, and the levels of the intermediates of the CO2 fixation cycle in the stroma of intact chloroplasts were assayed by ion exchange chromatography.2. The addition of the ionophore caused an increase of NADPH, ATP, fructose- and sedoheptulosebisphosphate and a dramatic decrease of phosphoglycerate in the stroma. These changes were reversed by the addition of Mg2+ and again affected by a subsequent addition of Ca2+. Ribulosebisphosphate and pentosemonophosphate levels in the stroma were only a little affected under these different conditions.3. The increase of the NADPH and ATP reflects the decreased utilization of these compounds due to the overall inhibition of CO2 fixation. As phosphoglycerate and triosephosphate appear to be in near equilibrium with NADPH and ATP, the decrease of phosphoglycerate seems to be a consequence of the changes in the nucleotide levels.4. The rapid increase of fructose- and sedoheptulosebisphosphate after the addition of the ionophore A 23187 clearly demonstrates that the overall inhibition of CO2 fixation caused by lowering the stromal Mg2+ is due to the inhibition of the hydrolysis of these sugar bisphosphates. It is concluded that the activities of fructose- and sedoheptulosebisphosphatase can be controlled by light dependent changes of the stromal Mg2+ concentration. 相似文献
63.
Sergei Gaidamakov Olga A. Maximova Hyongi Chon Nathan H. Blewett Hongsheng Wang Amanda K. Crawford Amanda Day Natalie Tulchin Robert J. Crouch Herbert C. Morse III Robert D. Blitzer Richard J. Maraia 《Molecular and cellular biology》2014,34(1):123-131
La antigen (Sjögren''s syndrome antigen B) is a phosphoprotein associated with nascent precursor tRNAs and other RNAs, and it is targeted by autoantibodies in patients with Sjögren''s syndrome, systemic lupus erythematosus, and neonatal lupus. Increased levels of La are associated with leukemias and other cancers, and various viruses usurp La to promote their replication. Yeast cells (Saccharomyces cerevisiae and Schizosaccharomyces pombe) genetically depleted of La grow and proliferate, whereas deletion from mice causes early embryonic lethality, raising the question of whether La is required by mammalian cells generally or only to surpass a developmental stage. We developed a conditional La allele and used it in mice that express Cre recombinase in either B cell progenitors or the forebrain. B cell Mb1Cre La-deleted mice produce no B cells. Consistent with αCamKII Cre, which induces deletion in hippocampal CA1 cells in the third postnatal week and later throughout the neocortex, brains develop normally in La-deleted mice until ∼5 weeks and then lose a large amount of forebrain cells and mass, with evidence of altered pre-tRNA processing. The data indicate that La is required not only in proliferating cells but also in nondividing postmitotic cells. Thus, La is essential in different cell types and required for normal development of various tissue types. 相似文献
64.
Pradeep Ruperao Chon‐Kit Kenneth Chan Sarwar Azam Miroslava Karafiátová Satomi Hayashi Jana Čížková Rachit K. Saxena Hana Šimková Chi Song Jan Vrána Annapurna Chitikineni Paul Visendi Pooran M. Gaur Teresa Millán Karam B. Singh Bunyamin Taran Jun Wang Jacqueline Batley Jaroslav Doležel Rajeev K. Varshney David Edwards 《Plant biotechnology journal》2014,12(6):778-786
With the expansion of next‐generation sequencing technology and advanced bioinformatics, there has been a rapid growth of genome sequencing projects. However, while this technology enables the rapid and cost‐effective assembly of draft genomes, the quality of these assemblies usually falls short of gold standard genome assemblies produced using the more traditional BAC by BAC and Sanger sequencing approaches. Assembly validation is often performed by the physical anchoring of genetically mapped markers, but this is prone to errors and the resolution is usually low, especially towards centromeric regions where recombination is limited. New approaches are required to validate reference genome assemblies. The ability to isolate individual chromosomes combined with next‐generation sequencing permits the validation of genome assemblies at the chromosome level. We demonstrate this approach by the assessment of the recently published chickpea kabuli and desi genomes. While previous genetic analysis suggests that these genomes should be very similar, a comparison of their chromosome sizes and published assemblies highlights significant differences. Our chromosomal genomics analysis highlights short defined regions that appear to have been misassembled in the kabuli genome and identifies large‐scale misassembly in the draft desi genome. The integration of chromosomal genomics tools within genome sequencing projects has the potential to significantly improve the construction and validation of genome assemblies. The approach could be applied both for new genome assemblies as well as published assemblies, and complements currently applied genome assembly strategies. 相似文献
65.
66.
A comprehensive, geometrically accurate, nonlinear C0-C7 FE model of head and cervical spine based on the actual geometry of a human cadaver specimen was developed. The motions of each cervical vertebral level under pure moment loading of 1.0 Nm applied incrementally on the skull to simulate the movements of the head and cervical spine under flexion, tension, axial rotation and lateral bending with the inferior surface of the C7 vertebral body fully constrained were analysed. The predicted range of motion (ROM) for each motion segment were computed and compared with published experimental data. The model predicted the nonlinear moment-rotation relationship of human cervical spine. Under the same loading magnitude, the model predicted the largest rotation in extension, followed by flexion and axial rotation, and least ROM in lateral bending. The upper cervical spines are more flexible than the lower cervical levels. The motions of the two uppermost motion segments account for half (or even higher) of the whole cervical spine motion under rotational loadings. The differences in the ROMs among the lower cervical spines (C3-C7) were relatively small. The FE predicted segmental motions effectively reflect the behavior of human cervical spine and were in agreement with the experimental data. The C0-C7 FE model offers potentials for biomedical and injury studies. 相似文献
67.
Zhong Y Jan KM Ju KH Chon KH 《American journal of physiology. Heart and circulatory physiology》2006,291(3):H1475-H1483
The ratio between low-frequency (LF) and high-frequency (HF) spectral power of heart rate has been used as an approximate index for determining the autonomic nervous system (ANS) balance. An accurate assessment of the ANS balance can only be achieved if clear separation of the dynamics of the sympathetic and parasympathetic nervous activities can be obtained, which is a daunting task because they are nonlinear and have overlapping dynamics. In this study, a promising nonlinear method, termed the principal dynamic mode (PDM) method, is used to separate dynamic components of the sympathetic and parasympathetic nervous activities on the basis of ECG signal, and the results are compared with the power spectral approach to assessing the ANS balance. The PDM analysis based on the 28 subjects consistently resulted in a clear separation of the two nervous systems, which have similar frequency characteristics for parasympathetic and sympathetic activities as those reported in the literature. With the application of atropine, in 13 of 15 supine subjects there was an increase in the sympathetic-to-parasympathetic ratio (SPR) due to a greater decrease of parasympathetic than sympathetic activity (P=0.003), and all 13 subjects in the upright position had a decrease in SPR due to a greater decrease of sympathetic than parasympathetic activity (P<0.001) with the application of propranolol. The LF-to-HF ratio calculated by the power spectral density is less accurate than the PDM because it is not able to separate the dynamics of the parasympathetic and sympathetic nervous systems. The culprit is equivalent decreases in both the sympathetic and parasympathetic activities irrespective of the pharmacological blockades. These findings suggest that the PDM shows promise as a noninvasive and quantitative marker of ANS imbalance, which has been shown to be a factor in many cardiac and stress-related diseases. 相似文献
68.
Takano K Endo S Mukaiyama A Chon H Matsumura H Koga Y Kanaya S 《The FEBS journal》2006,273(1):150-158
Conformational studies on amyloid beta peptide (Abeta) in aqueous solution are complicated by its tendency to aggregate. In this study, we determined the atomic-level structure of Abeta(28-42) in an aqueous environment. We fused fragments of Abeta, residues 10-24 (Abeta(10-24)) or 28-42 (Abeta(28-42)), to three positions in the C-terminal region of ribonuclease HII from a hyperthermophile, Thermococcus kodakaraensis (Tk-RNase HII). We then examined the structural properties in an aqueous environment. The host protein, Tk-RNase HII, is highly stable and the C-terminal region has relatively little interaction with other parts. CD spectroscopy and thermal denaturation experiments demonstrated that the guest amyloidogenic sequences did not affect the overall structure of the Tk-RNase HII. Crystal structure analysis of Tk-RNase HII(1-197)-Abeta(28-42) revealed that Abeta(28-42) forms a beta conformation, whereas the original structure in Tk-RNase HII(1-213) was alpha helix, suggesting beta-structure formation of Abeta(28-42) within full-length Abeta in aqueous solution. Abeta(28-42) enhanced aggregation of the host protein more strongly than Abeta(10-24). These results and other reports suggest that after proteolytic cleavage, the C-terminal region of Abeta adopts a beta conformation in an aqueous environment and induces aggregation, and that the central region of Abeta plays a critical role in fibril formation. This study also indicates that this fusion technique is useful for obtaining structural information with atomic resolution for amyloidogenic peptides in aqueous environments. 相似文献
69.
Interactions among physiological mechanisms are abundant in biomedical signals, and they may exist to maintain efficient homeostasis. For example, sympathetic and parasympathetic neural activities interact to either elevate or depress the heart rate to maintain homeostasis. There has been considerable effort devoted to developing algorithms that can detect interactions between various physiological mechanisms. However, methods used to detect the presence of interactions between the sympathetic and parasympathetic nervous systems, to take one example, have had limited success. This may be because interactions in physiological systems are non-linear and non-stationary. The goal of this work was to identify non-linear interactions between the sympathetic and parasympathetic nervous systems in the form of frequency and amplitude modulations in human heart-rate data (n=6). To this end, wavelet analysis was performed, followed by frequency analysis of the resultant wavelet decomposed signals in several frequency brackets we define as: very low frequency (f<0.04 Hz), low frequency (0.04-0.15 Hz) and high frequency (0.15-0.4 Hz). Our analysis suggests that the high-frequency bracket is modulated by the low-frequency bracket in the heart rate data obtained in both upright and sitting positions. However, there was no evidence of amplitude modulation among these frequencies. 相似文献
70.
Mi Sung Park Beom Kyung Kim Jae Yoeun Cheong Dong Joon Kim Jun Yong Park Do Young Kim Sang Hoon Ahn Kwang-Hyub Han Chae Yoon Chon Seung Up Kim 《PloS one》2013,8(2)