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981.
By varying the solvents and temperatures under solvothermal conditions, two new magnesium based coordination networks were synthesized using 2,5-thiophenedicarbxoylate as a linker. Mg3(TDC)3(DMF)3 [1; TDC = 2,5 thiophenedicarboxylate; space group P21/c, a = 17.747(4) Å, b = 9.805(2) Å, c = 21.359(4) Å, β = 103.13(3)°] is constructed by a combination of magnesium polyhedral trimers, which are connected by the TDC2− linkers to form a 3-D network. Coordinated DMF molecules are present within the channels. Mg(TDC)(H2O)2 [2; space group Pnma, a = 7.296(4) Å, b = 17.760(4) Å, c = 6.6631(3) Å] is formed by 1-D chains of magnesium octahedra connected by the TDC2− linker. Water molecules are coordinated at the axial positions of the magnesium octahedra. Compound 1 is formed using DMF as the synthesis solvent at 180 °C, while compound 2 is formed using ethanol as the synthesis solvent at 100 °C. Both compounds show enhanced photoluminescence intensity when excited at 397 nm compared to the free TDC ligand, suggesting a charge transfer between the ligand and the magnesium metal center. 相似文献
982.
Although several Gram-positive denitrifiers have been characterized in the past, there is still uncertainty about the occurrence of the denitrification trait among these bacteria. In an isolation campaign on luvisol soil, Bacillus spp. were among the most abundant retrieved cultured denitrifiers next to members of Rhizobiaceae family and genus Cupriavidus. Subsequent screening of 180 representatives of the genus Bacillus (encompassing more than half of the current validly described species diversity in Bacillus) was performed and demonstrated the potential for dissimilatory reduction of nitrogen compounds in 45 of the 87 investigated species, with 19 species containing denitrifying members. The influence of several electron donors and acceptors was tested. The use of more than one electron acceptor, e.g. both nitrate and nitrite, was crucial to detect the denitrification potential of reference strains. Complex electron donors, most suitable for aerobic growth, were ideal for denitrification testing, while retrieval of denitrifiers from the environment was facilitated by the use of defined electron donors, due to less interference of other anaerobic growers. The outcome of the isolation campaign and screening of reference strain set suggest that bacilli may be potential contributors to denitrification in terrestrial and possibly other ecosystems. 相似文献
983.
Human exposure to nanoparticles is inevitable from natural and anthropogenic sources. Titanium dioxide (TiO2) nanoparticles are increasingly being used in pharmaceutical and cosmetic products. Previous studies revealed that TiO2 levels were significantly increased in tissues (e.g., lymph nodes) after mice were injected with nanosized TiO2. To identify early response lymph node proteins to TiO2 nanoparticles, groups of mice were intradermally injected with a low dose of DeGussa P25 TiO2 nanoparticles or vehicle alone. The proteomes of lymph nodes at 24 h were quantitatively analyzed using trypsin-catalyzed 16O/18O labeling in conjunction with two-dimensional liquid chromatography separation and tandem mass spectrometry (2DLC-MS/MS). A total of 33 proteins were significantly changed (over 1.3-fold, p<0.05) in the mice treated with TiO2 nanoparticles, which accounted for approximately 1% of the total proteins identified. The differentially expressed proteins mainly involve the immune response (e.g., inflammation), lipid and fatty acid metabolism, mRNA processing, and nucleosome assembly. Regulation of functionally distinct classes of proteins could be mediated by estrogen receptor (ESR1), PPARγ, and c-Myc signalings, etc. The differentially expressed proteins identified in this experiment could represent early response proteins to TiO2 nanoparticle treatment in mouse lymph nodes. 相似文献
984.
985.
ZINBA (Zero-Inflated Negative Binomial Algorithm) identifies genomic regions enriched in a variety of ChIP-seq and related
next-generation sequencing experiments (DNA-seq), calling both broad and narrow modes of enrichment across a range of signal-to-noise
ratios. ZINBA models and accounts for factors that co-vary with background or experimental signal, such as G/C content, and
identifies enrichment in genomes with complex local copy number variations. ZINBA provides a single unified framework for
analyzing DNA-seq experiments in challenging genomic contexts. 相似文献
986.
Background
Gamma (γ) oscillations (30–50 Hz) have been shown to be excessive in patients with schizophrenia (SCZ) during working memory (WM). WM is a cognitive process that involves the online maintenance and manipulation of information that is mediated largely by the dorsolateral prefrontal cortex (DLPFC). Repetitive transcranial magnetic stimulation (rTMS) represents a non-invasive method to stimulate the cortex that has been shown to enhance cognition and γ oscillatory activity during WM.Methodology and Principal Findings
We examined the effect of 20 Hz rTMS over the DLPFC on γ oscillatory activity elicited during the N-back task in 24 patients with SCZ compared to 22 healthy subjects. Prior to rTMS, patients with SCZ elicited excessive γ oscillatory activity compared to healthy subjects across WM load. Active rTMS resulted in the reduction of frontal γ oscillatory activity in patients with SCZ, while potentiating activity in healthy subjects in the 3-back, the most difficult condition. Further, these effects on γ oscillatory activity were found to be specific to the frontal brain region and were absent in the parieto-occipital brain region.Conclusions and Significance
We suggest that this opposing effect of rTMS on γ oscillatory activity in patients with SCZ versus healthy subjects may be related to homeostatic plasticity leading to differential effects of rTMS on γ oscillatory activity depending on baseline differences. These findings provide important insights into the neurophysiological mechanisms underlying WM deficits in SCZ and demonstrated that rTMS can modulate γ oscillatory activity that may be a possible avenue for cognitive potentiation in this disorder. 相似文献987.
Bees exposed to vigorous shaking designed to simulate a dangerous event judge ambiguous stimuli as predicting a negative outcome - a 'pessimistic' cognitive bias that is characteristic of anxious or depressed humans and other vertebrates in putative negative emotional states. 相似文献
988.
Eltit JM Feng W Lopez JR Padilla IT Pessah IN Molinski TF Fruen BR Allen PD Perez CF 《The Journal of biological chemistry》2010,285(49):38453-38462
Previously, we have shown that lack of expression of triadins in skeletal muscle cells results in significant increase of myoplasmic resting free Ca(2+) ([Ca(2+)](rest)), suggesting a role for triadins in modulating global intracellular Ca(2+) homeostasis. To understand this mechanism, we study here how triadin alters [Ca(2+)](rest), Ca(2+) release, and Ca(2+) entry pathways using a combination of Ca(2+) microelectrodes, channels reconstituted in bilayer lipid membranes (BLM), Ca(2+), and Mn(2+) imaging analyses of myotubes and RyR1 channels obtained from triadin-null mice. Unlike WT cells, triadin-null myotubes had chronically elevated [Ca(2+)](rest) that was sensitive to inhibition with ryanodine, suggesting that triadin-null cells have increased basal RyR1 activity. Consistently, BLM studies indicate that, unlike WT-RyR1, triadin-null channels more frequently display atypical gating behavior with multiple and stable subconductance states. Accordingly, pulldown analysis and fluorescent FKBP12 binding studies in triadin-null muscles revealed a significant impairment of the FKBP12/RyR1 interaction. Mn(2+) quench rates under resting conditions indicate that triadin-null cells also have higher Ca(2+) entry rates and lower sarcoplasmic reticulum Ca(2+) load than WT cells. Overexpression of FKBP12.6 reverted the null phenotype, reducing resting Ca(2+) entry, recovering sarcoplasmic reticulum Ca(2+) content levels, and restoring near normal [Ca(2+)](rest). Exogenous FKBP12.6 also reduced the RyR1 channel P(o) but did not rescue subconductance behavior. In contrast, FKBP12 neither reduced P(o) nor recovered multiple subconductance gating. These data suggest that elevated [Ca(2+)](rest) in triadin-null myotubes is primarily driven by dysregulated RyR1 channel activity that results in part from impaired FKBP12/RyR1 functional interactions and a secondary increased Ca(2+) entry at rest. 相似文献
989.
Centrosomes comprise a pair of centrioles surrounded by an amorphous network of pericentriolar material (PCM). In certain stem cells, the two centrosomes differ in size, and this appears to be important for asymmetric cell division [1, 2]. In some cases, centrosome asymmetry is linked to centriole age because the older, mother centriole always organizes more PCM than the daughter centriole, thus ensuring that the mother centriole is always retained in the stem cell after cell division [3]. This has raised the possibility that an "immortal" mother centriole may help maintain stem cell fate [4, 5]. It is unclear, however, how centrosome size asymmetry is generated in stem cells. Here we provide compelling evidence that centrosome size asymmetry in Drosophila neuroblasts is generated by the differential regulation of Cnn incorporation into the PCM at mother and daughter centrioles. Shortly after centriole separation, mother and daughter centrioles organize similar amounts of PCM, but Cnn incorporation is then rapidly downregulated at the mother centriole, while it is maintained at the daughter centriole. This ensures that the daughter centriole maintains its PCM and so its position at the apical cortex. Thus, the?daughter centriole, rather than an "immortal" mother centriole, is ultimately retained in these stem cells. 相似文献
990.
Admixture in Mexico City: implications for admixture mapping of Type 2 diabetes genetic risk factors
Martinez-Marignac VL Valladares A Cameron E Chan A Perera A Globus-Goldberg R Wacher N Kumate J McKeigue P O'Donnell D Shriver MD Cruz M Parra EJ 《Human genetics》2007,120(6):807-819
Admixture mapping is a recently developed method for identifying genetic risk factors involved in complex traits or diseases
showing prevalence differences between major continental groups. Type 2 diabetes (T2D) is at least twice as prevalent in Native
American populations as in populations of European ancestry, so admixture mapping is well suited to study the genetic basis
of this complex disease. We have characterized the admixture proportions in a sample of 286 unrelated T2D patients and 275
controls from Mexico City and we discuss the implications of the results for admixture mapping studies. Admixture proportions
were estimated using 69 autosomal ancestry-informative markers (AIMs). Maternal and paternal contributions were estimated
from geographically informative mtDNA and Y-specific polymorphisms. The average proportions of Native American, European and,
West African admixture were estimated as 65, 30, and 5%, respectively. The contributions of Native American ancestors to maternal
and paternal lineages were estimated as 90 and 40%, respectively. In a logistic model with higher educational status as dependent
variable, the odds ratio for higher educational status associated with an increase from 0 to 1 in European admixture proportions
was 9.4 (95%, credible interval 3.8–22.6). This association of socioeconomic status with individual admixture proportion shows
that genetic stratification in this population is paralleled, and possibly maintained, by socioeconomic stratification. The
effective number of generations back to unadmixed ancestors was 6.7 (95% CI 5.7–8.0), from which we can estimate that genome-wide
admixture mapping will require typing about 1,400 evenly distributed AIMs to localize genes underlying disease risk between
populations of European and Native American ancestry. Sample sizes of about 2,000 cases will be required to detect any locus
that contributes an ancestry risk ratio of at least 1.5. 相似文献