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61.
Pastrana-Rios B Ocaña W Rios M Vargas GL Ysa G Poynter G Tapia J Salisbury JL 《Biochemistry》2002,41(22):6911-6919
Centrin is a low molecular mass (20 kDa) protein that belongs to the EF-hand superfamily of calcium-binding proteins. Local and overall changes were investigated for interactions between cations and Chlamydomonas centrin using Fourier transform infrared (FT-IR) and circular dichroic (CD) spectroscopies. FT-IR spectral features studied included the amide I' band and the side-chain absorbances for aspartate residues located almost exclusively at the calcium-binding sites in the spectral region of 1700-1500 cm(-1). The amide I' band is exquisitely sensitive to changes in protein secondary structure and is observed to shift from 1626.5 to 1642.7 cm(-1) in the presence and absence of calcium. These spectral bands are complex and were further studied using two-dimensional Fourier transform infrared (2D-FT-IR) correlation along with curve-fitting routines. Using these methods the secondary structure contributions were determined for holocentrin and apocentrin. The alpha-helical content in centrin was determined to be 60%-53% in the presence and absence of cations, respectively. Furthermore, the beta-strand content was determined to be 12%-36%, while the random coil component remained almost constant at 7%-13.5% in the presence and absence of cations, respectively. Changes in the side-chain band are mostly due to the monodentate coordination of aspartate to the cation. A shift of approximately 4 cm(-1) (for the COO- antisymmetric stretch in Asp) from 1565 to 1569 cm(-1) is observed for apocentrin and holocentrin, respectively. Thermal dependence revealed reversible conformational transition temperatures for apocentrin at 37 degrees C and holocentrin at 45 degrees C, suggesting greater stability for holocentrin. 相似文献
62.
Johnson KR Lane PW Cook SA Harris BS Ward-Bailey PF Bronson RT Lyons BL Shultz LD Davisson MT 《Genomics》2003,81(1):6-14
In the outcrossing of a new recessive mouse mutation causing hair loss, a new wavy-coated phenotype appeared. The two distinct phenotypes were shown to be alternative manifestations of the same gene mutation and attributable to a single modifier locus. The new mutation, curly bare (cub), was mapped to distal Chr 11 and the modifier (mcub) was mapped to Chr 5. When homozygous for the recessive mcub allele, cub/cub mice appear hairless. A single copy of the dominant Mcub allele confers a full, curly coat in cub/cub mice. Reciprocal transfer of full-thickness skin grafts between mutant and control animals showed that the skin phenotype was tissue autonomous. The hairless cub/cub mcub/mcub mice show normal contact sensitivity responses to oxazolone. The similarity of the wavy coat phenotype to those of Tgfa and Egfr mutations and the map positions of cub and mcub suggest candidate genes that interact in the EGF receptor signal transduction pathway. 相似文献
63.
64.
The spindle checkpoint control mechanism functions to ensure faithful chromosome segregation by delaying cell division until all chromosomes are correctly oriented on the mitotic spindle. Initially identified in budding yeast, several mammalian spindle checkpoint-associated proteins have recently been identified and partially characterized. These proteins associate with all active human centromeres, including neocentromeres, in the early stages of mitosis prior to the commencement of anaphase. We have examined the status of proteins associated with the checkpoint protein complex (BUB1, BUBR1, BUB3, MAD2), the anaphase-promoting complex (Tsg24, p55CDC), and other proteins associated with mitotic checkpoint control (ERK1, 3F3/2 epitope, hZW10), on a human dicentric chromosome. Each of these proteins was found to specifically associate with only the active centromere, suggesting that only active centromeres participate in the spindle checkpoint. This finding complements previous studies on multicentric chromosomes demonstrating specific association of structural and motor-related centromere proteins with active centromeres, and suggests that centromere inactivation is accompanied by loss of all functionally important centromere proteins. 相似文献
65.
The Gcn4p Activation Domain Interacts Specifically In Vitro with RNA Polymerase II Holoenzyme, TFIID, and the Adap-Gcn5p Coactivator Complex 总被引:10,自引:8,他引:2 下载免费PDF全文
66.
Chiara Donfrancesco Simonetta Palleschi Luigi Palmieri Barbara Rossi Cinzia Lo Noce Fabio Pannozzo Belinda Spoto Giovanni Tripepi Carmine Zoccali Simona Giampaoli 《PloS one》2013,8(10)
Background
Chronic kidney disease (CKD) independently increases the risk of death and cardiovascular disease (CVD) in the general population. However, the relationship between estimated glomerular filtration rate (eGFR) and CVD/death risk in a general population at low risk of CVD has not been explored so far.Design
Baseline and longitudinal data of 1465 men and 1459 women aged 35-74 years participating to the MATISS study, an Italian general population cohort, were used to evaluate the role of eGFR in the prediction of all-cause mortality and incident CVD.Methods
Bio-bank stored sera were used to evaluate eGFR at baseline. Serum creatinine was measured on thawed samples by means of an IDMS-calibrated enzymatic method. eGFR was calculated by the CKD-EPI formula.Results
At baseline, less than 2% of enrolled persons had eGFR < 60 mL/min/1.73m2 and more than 70% had a 10-year cardiovascular risk score < 10%. In people 60 or more years old, the first and the last eGFR quintiles (<90 and ≥109 mL/min/1.73m2, respectively) were associated to an increased risk for both all-cause mortality (hazard ratio 1.6, 95% confidence interval 1.2-2.1 and 4.3, 1.6-11.7, respectively) and incident CVD (1.6, 1.0-2.4 and 7.0, 2.2-22.9, respectively), even if adjusted for classical risk factors.Conclusions
These findings strongly suggest that in an elderly, general population at low risk of CVD and low prevalence of reduced renal filtration, even a modest eGFR reduction is related to all-cause mortality and CVD incidence, underlying the potential benefit to this population of considering eGFR for their risk prediction. 相似文献67.
Holowatz LA Houghton BL Wong BJ Wilkins BW Harding AW Kenney WL Minson CT 《American journal of physiology. Heart and circulatory physiology》2003,284(5):H1662-H1667
Thermoregulatory cutaneous vasodilation is diminished in the elderly. The goal of this study was to test the hypothesis that a reduction in nitric oxide (NO)-dependent mechanisms contributes to the attenuated reflex cutaneous vasodilation in older subjects. Seven young (23 +/- 2 yr) and seven older (71 +/- 6 yr) men were instrumented with two microdialysis fibers in the forearm skin. One site served as control (Ringer infusion), and the second site was perfused with 10 mM N(G)-nitro-l-arginine methyl ester to inhibit NO synthase (NOS) throughout the protocol. Water-perfused suits were used to raise core temperature 1.0 degrees C. Red blood cell (RBC) flux was measured with laser-Doppler flowmetry over each microdialysis fiber. Cutaneous vascular conductance (CVC) was calculated as RBC flux per mean arterial pressure, with values expressed as a percentage of maximal vasodilation (infusion of 28 mM sodium nitroprusside). NOS inhibition reduced CVC from 75 +/- 6% maximal CVC (CVC(max)) to 53 +/- 3% CVC(max) in the young subjects and from 64 +/- 5% CVC(max) to 29 +/- 2% CVC(max) in the older subjects with a 1.0 degrees C rise in core temperature. Thus the relative NO-dependent portion of cutaneous active vasodilation (AVD) accounted for approximately 23% of vasodilation in the young subjects and 60% of the vasodilation in the older subjects at this level of hyperthermia (P < 0.001). In summary, NO-mediated pathways contributed more to the total vasodilatory response of the older subjects at high core temperatures. This suggests that attenuated cutaneous vasodilation with age may be due to a reduction in, or decreased vascular responsiveness to, the unknown neurotransmitter(s) mediating AVD. 相似文献
68.
Previous investigations into the evolution of the Drosophila opsin gene family are extended by inter- and intraspecific DNA sequence comparisons of the Rh3 locus in the melanogaster subgroup and D. pseudoobscura. Two separate statistical tests of the neutral-mutation hypothesis suggest that random genetic drift is responsible for virtually all of the observed amino acid replacement substitutions within the melanogaster subgroup. Analyses incorporating the D. pseudoobscura sequences are enigmatic due to the accumulation of multiple substitutions, because the McDonald-Kreitman test is not applicable to species comparisons that approach mutational saturation. However, the data from D. pseudoobscura are not inconsistent with selective neutrality. The ratio of amino acid polymorphisms within species to fixed differences between species imply that these are approximately 31 possible neutral single-step amino-acid-replacement substitutions at this locus. Synonymous substitutions are unevenly distributed among the structural domains of the Rh3 gene. Patterns of synonymous polymorphism are analyzed with respect to GC content and codon bias, and are compared to other loci from the same species. 相似文献
69.
Evolutionary dynamics of Rh2 opsins in birds demonstrate an episode of accelerated evolution in the New World warblers (Setophaga) 下载免费PDF全文
Low rates of sequence evolution associated with purifying selection can be interrupted by episodic changes in selective regimes. Visual pigments are a unique system in which we can investigate the functional consequences of genetic changes, therefore connecting genotype to phenotype in the context of natural and sexual selection pressures. We study the RH2 and RH1 visual pigments (opsins) across 22 bird species belonging to two ecologically convergent clades, the New World warblers (Parulidae) and Old World warblers (Phylloscopidae) and evaluate rates of evolution in these clades along with data from 21 additional species. We demonstrate generally slow evolution of these opsins: both Rh1 and Rh2 are highly conserved across Old World and New World warblers. However, Rh2 underwent a burst of evolution within the New World genus Setophaga, where it accumulated substitutions at 6 amino acid sites across the species we studied. Evolutionary analyses revealed a significant increase in dN/dS in Setophaga, implying relatively strong selective pressures to overcome long‐standing purifying selection. We studied the effects of each substitution on spectral tuning and found they do not cause large spectral shifts. Thus, substitutions may reflect other aspects of opsin function, such as those affecting photosensitivity and/or dark–light adaptation. Although it is unclear what these alterations mean for colour perception, we suggest that rapid evolution is linked to sexual selection, given the exceptional plumage colour diversification in Setophaga. 相似文献
70.
Belinda Martineau H. Jane Smith Caroline Dean Pamela Dunsmuir John Bedbrook Laurens J. Mets 《Plant molecular biology》1989,13(4):419-426
We report the successful transformation, via Agrobacterium tumefaciens infection, and regeneration of two species of the genus Flaveria: F. brownii and F. palmeri. We document the expression of a C3 plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these C4 plants. The organ-specific expression of this petunia gene in Flaveria brownii is qualitatively identical to its endogenous pattern of expression. 相似文献