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921.
Sergio Camero María J. Benítez Raquel Cuadros Félix Hernández Jesús ávila Juan S. Jiménez 《PloS one》2014,9(8)
Tau hyperphosphorylation can be considered as one of the hallmarks of Alzheimer''s disease and other tauophaties. Besides its well-known role as a microtubule associated protein, Tau displays a key function as a protector of genomic integrity in stress situations. Phosphorylation has been proven to regulate multiple processes including nuclear translocation of Tau. In this contribution, we are addressing the physicochemical nature of DNA-Tau interaction including the plausible influence of phosphorylation. By means of surface plasmon resonance (SPR) we measured the equilibrium constant and the free energy, enthalpy and entropy changes associated to the Tau-DNA complex formation. Our results show that unphosphorylated Tau binding to DNA is reversible. This fact is in agreement with the protective role attributed to nuclear Tau, which stops binding to DNA once the insult is over. According to our thermodynamic data, oscillations in the concentration of dephosphorylated Tau available to DNA must be the variable determining the extent of Tau binding and DNA protection. In addition, thermodynamics of the interaction suggest that hydrophobicity must represent an important contribution to the stability of the Tau-DNA complex. SPR results together with those from Tau expression in HEK cells show that phosphorylation induces changes in Tau protein which prevent it from binding to DNA. The phosphorylation-dependent regulation of DNA binding is analogous to the Tau-microtubules binding inhibition induced by phosphorylation. Our results suggest that hydrophobicity may control Tau location and DNA interaction and that impairment of this Tau-DNA interaction, due to Tau hyperphosphorylation, could contribute to Alzheimer''s pathogenesis. 相似文献
922.
A. Blanco-Molina D. Martín-Escalante D. Bravo J. A. González-Reyes J. López-Miranda J. M. Ordovás F. López-Segura J. A. Jiménez-Péreperez F. Pérez-Jiménez 《Protoplasma》2000,211(3-4):198-206
Summary Endothelial lesion by oxidized low-density liproproteins (LDL) is one of the first stages in the development of atherosclerosis. The effect of these lipoproteins can range from a functional lesion of the endothelium to death of the endothelial cells by apoptosis. High-density lipoproteins (HDL) are one of the factors which can have a protective effect against the development of atheromatous plaques. The aim of this study is to establish whether the death of endothelial cells by apoptosis induced by oxidized LDLs is prevented by HDLs. ECV304 endothelial cells and bovine aorta endothelial cells were incubated with native LDLs, oxidized LDLs, and a combination of both oxidized LDLs and HDLs. Oxidized LDLs caused a significant increase of mortality mainly by apoptosis. However, when HDLs were added together with oxidized LDLs the percentage of total mortality, the degree of lipoprotein oxidation in the medium, and the percentage of cells in apoptosis were all significantly decreased. HDLs protect against the cytotoxicity of oxidized LDLs possibly by preventing the propagation of the oxidative chain in these lipoproteins.Abbreviations LDL
low-density lipoproteins
- HDL
high-density lipoproteins
- BAEC
bovine aortic endothelial cell
- TBARS
thiobarbituric acid-reactive substances 相似文献
923.
Flavia M. Lucena Teodoro Vaske Jim R. Ellis Carl M. O'Brien 《Environmental Biology of Fishes》2000,57(4):423-434
The stomach contents of 516 Pomatomus saltatrix and 506 Cynoscion guatucupa from southern Brazil were examined. Both species preyed primarily upon teleosts and crustaceans and occasionally squid. Seasonal variation in the diet was related to prey availability in the area, confirming the opportunistic feeding behaviour of both species. During the summer, P. saltatrix preyed upon four prey species (Loligo sanpaulensis, Artemesia longinaris, Mullus argentinae and Paralonchurus brasiliensis), whereas in the autumn and winter Engraulis anchoita was the predominant prey. C. guatucupa similarly preyed upon A. longinaris and P. brasiliensis during the summer, with juvenile C. guatucupa and E. anchoita also consumed. The latter species was an important dietary constituent during other seasons, as were A. longinaris (autumn), Umbrina canosai (winter), Trachurus latami and euphausids (spring). Although P. saltatrix had a broader diet than C. guatucupa during the summer, the latter species had a broader diet overall. Diet breadths were lower from autumn to spring, due to the predominance of E. anchoita in the diet of both species. This restricted diet resulted in significant intra- and inter-specific diet overlap during the winter but, because of the seasonal abundance of E. anchoita, the high levels of diet overlap do not necessarily indicate competition. 相似文献
924.
2B rye plants selected for high (H) or low (L) B transmission rate were studied at pachytene and metaphase I of meiosis to determine the relationship between synapsis, bivalents at metaphase I, and B transmission rate. The results show that the 2 B chromosomes (Bs) form bivalents at pachytene in both the H and L lines, whereas the frequency of bivalents at metaphase I is much higher in the H than in the L line. This demonstrates that B transmission is mainly related to the proper association of Bs at metaphase I, as well as that synapsis of the 2 Bs in the L line is normal, but the bivalent is not consolidated by a chiasma in most cases. Crosses were made between 2B plants of the H and L lines in all combinations (H x H, H x L, L x H, and L x L) to obtain 4B plants. Similarly, bivalent formation at pachytene and metaphase I was studied. The results show that 4B plants of the H x H and L x L classes differ significantly at pachytene and metaphase I since the former forms more bivalents. The heterozygous 4 Bs of the H x L and L x H classes show intermediate values. The relation H x H > H x L > L x H > L x L was consistently found for the variables transmission rate, bivalents at pachytene, bivalents at metaphase I, and B mean chiasma frequency. A maternal effect was also found. Our data suggest that there are two separate mechanisms acting upon synapsis and chiasma formation in H and L B chromosomes: (i) there is variable efficiency of the control of synapsis at early stages of meiosis; and (ii) there is variable efficiency of the control of the number of chiasmata. 相似文献
925.
Jim Waterhouse Dietmar Weinert David Minors Simon Folkard Deborah Owens Greg Atkinson Alan Nevill Thomas Reilly 《Biological Rhythm Research》2000,31(1):88-107
Fifteen healthy female subjects were studied for eight days while living conventionally. Subjects were free to choose the ways they spent their time within a framework of regular times of retiring and rising; in practice, much of the waking time was spent in sedentary activities. Nine of the subjects were aware of the natural light-dark cycle, this approximating to a 12:12 L:D schedule at the time of year when the study took place. Before the study, subjects were assessed for their degree of "morningness" by questionnaire; throughout the study, they wore a rectal probe, and an activity meter on their non-dominant wrist. The timing (phase) and amplitude of the circadian rectal temperature rhythm were assessed on each day by cosinor analysis as well as by a me thod based on visual inspection of the data. These two parameters were also assessed after the temperature data for each day had been "purified" by a number of methods. From these results it was possible to investigate the effect of purification upon the amplitude of the circadian rhythm of temperature. Also, the day-by-day variability of phase, and the relationship between morningness and phase, were compared using these methods of phase estimation, and using cross-correlation between data sets from adjacent days; in all cases, raw and purified temperature data were used. There was a significantly greater amount of daily variation in phase using purified rather than raw data sets, and this difference was present with all methods of purification as well as with all methods for estimating phase. Purifi cation decreased the amplitude of the circadian temperature rhythm by about 30%. Finally, there was a significant correlation between the morningness score of the subjects and the phase of the circadian temperature rhythm, the phase becoming earlier with increasing morningness; when this relationship was re-examined using purified data, it became more marked. These results reflect the masking effects exerted upon raw temperature data by lifestyle. The extent to which the purification methods enable the endogenous component of a circadian rhythm - and, by implication, the output of the endogenous circadian oscillator - to be estimated in subjects living normally is addressed. 相似文献
926.
Joël Gellin Steve Brown Jennifer A. Marshall Graves Max Rothschild Lawrence Schook Jim Womack Martine Yerle 《Mammalian genome》2000,11(2):140-144
Following the successful Comparative Mapping Workshop held at Fraser Island, Australia in 1995, HUGO organized a second workshop
of 41 invited participants, held at Toulouse, France on May 3 and 4, 1999. The aim of the conference was to focus on recent
developments in genome mapping in a variety of vertebrate species, with particular emphasis on progress in farm animals (cattle,
pigs, chickens, sheep, horses, goats, and deer). In addition, representatives from important experimental mammalian and vertebrate
organisms (e.g. mice, rats, dogs, fugu, and marsupials) also participated in the meeting. After a rapid overview of developments
in the construction and comparison of genome maps in a wide variety of species, discussion focused on how comparative genomics
will play a vital role in the genetic dissection of multigenic traits and the characterization of agriculturally important
loci in agricultural species. Acceleration of gene discovery with heterologous ESTs (Expressed Sequence Tags) or collections
of ESTs was discussed. Recent developments in the construction of cDNA libraries and the efficiency of tools such as whole
genome radiation hybrids (RH) and large fragment clone libraries (YACs and in particular BACs) were discussed. Proposed criteria
to improve the identification of homologous genes between species and recommendations for nomenclatures were identified. Particular
emphasis was placed on how the integration of biological databases could help the scientific community.
Received: 13 July 1999 / Accepted: 20 September 1999 相似文献
927.
928.
Deng S Chen SN Lu J Wang ZJ Nikolic D van Breemen RB Santarsiero BD Mesecar A Fong HH Farnsworth NR Pauli GF 《Phytochemical analysis : PCA》2006,17(6):398-405
The methanol extract of Angelica sinensis (Oliv.) Diels roots (Dang Gui) has been shown to exhibit competitive binding to the GABAa receptor, suggesting the presence of GABAergic ligands. Chromatographic fractionation of the methanol extract led to the isolation of two GABAergic dimeric phthalides 1 and 2. Gelispirolide (1) was elucidated as a new phthalide dimer composed of a Z-ligustilide and a Z-butylidenephthalide unit on the basis of spectroscopic approaches including one- and two-dimensional NMR, HRESIMS and HRESIMS-MS. Compound 2 was identified as the known dimeric phthalide, riligustilide, by comparison of its spectroscopic data with literature values. Its dimeric linkage and stereochemistry were ascertained by a single crystal X-ray diffraction experiment. Both dimers 1 and 2 were found to be active in an in vitro GABAa receptor-binding assay with IC50 values of 29 and 24 microM, respectively. 相似文献
929.
Hayes EK Lechowicz A Petrik JJ Storozhuk Y Paez-Parent S Dai Q Samjoo IA Mansell M Gruslin A Holloway AC Raha S 《PloS one》2012,7(3):e33370
Maternal obesity results in a number of obstetrical and fetal complications with both immediate and long-term consequences. The increased prevalence of obesity has resulted in increasing numbers of women of reproductive age in this high-risk group. Since many of these obese women have been subjected to hypercaloric diets from early childhood we have developed a rodent model of life-long maternal obesity to more clearly understand the mechanisms that contribute to adverse pregnancy outcomes in obese women. Female Sprague Dawley rats were fed a control diet (CON--16% of calories from fat) or high fat diet (HF--45% of calories from fat) from 3 to 19 weeks of age. Prior to pregnancy HF-fed dams exhibited significant increases in body fat, serum leptin and triglycerides. A subset of dams was sacrificed at gestational day 15 to evaluate fetal and placental development. The remaining animals were allowed to deliver normally. HF-fed dams exhibited a more than 3-fold increase in fetal death and decreased neonatal survival. These outcomes were associated with altered vascular development in the placenta, as well as increased hypoxia in the labyrinth. We propose that the altered placental vasculature may result in reduced oxygenation of the fetal tissues contributing to premature demise and poor neonatal survival. 相似文献
930.