40 resultados para 1460


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Shortly after the founding of the University of Basel (1460), there was a reform conflict that was sparked by the election of the Rector and the question oft he future leadership of the University. A group of mostly aristocratic and honorable lawyers (being verified prosopographically in the article), supported of influential people of the city of Basel, tried to introduce an Italian constitution modeled after the Law-University of Bologna contrary to the habits north of the Alps. The plan failed, and the group was made reform losers, because the universities of the German speaking countries had developed into ‚Four-Faculties-Universities‘ with regularly changing leadership, in which the faculty of arts frequentially and financially set the tone. To compensate the Basel University, the first in the Empire, created an ordo differencie in which the different social ranks of University attendees already noticed in practice were also laid down by statute.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The AXR6 gene is required for auxin signaling in the Arabidopsis embryo and during postembryonic development. One of the effects of auxin is to stimulate degradation of the Aux/IAA auxin response proteins through the action of the ubiquitin protein ligase SCFTIR1. Here we show that AXR6 encodes the SCF subunit CUL1. The axr6 mutations affect the ability of mutant CUL1 to assemble into stable SCF complexes resulting in reduced degradation of the SCFTIR1 substrate AXR2/IAA7. In addition, we show that CUL1 is required for lateral organ initiation in the shoot apical meristem and the inflorescence meristem. These results indicate that the embryonic axr6 phenotype is related to a defect in SCF function and accumulation of Aux/IAA proteins such as BDL/IAA12. In addition, we show that CUL1 has a role in auxin response throughout the life cycle of the plant.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fluctuations in the Δ14C curve and subsequent gaps of archaeological findings at 800–650 and 400–100 BC in western and central Europe may indicate major climate-driven land-abandonment phases. To address this hypothesis radiocarbon-dated sediments from four lakes in Switzerland were studied palynologically. Pollen analysis indicates contemporaneous phases of forest clearances and of intensified land-use at 1450–1250 BC, 650–450 BC, 50 BC–100 AD and around 700 AD. These land-use expansions coincided with periods of warm climate as recorded by the Alpine dendroclimatic and Greenland oxygen isotope records. Our results suggest that harvest yields would have increased synchronously over wide areas of central and southern Europe during periods of warm and dry climate. Combined interpretation of palaeoecological and archaeological findings suggests that higher food production led to increased human populations. Positive long-term trends in pollen values of Cerealia and Plantago lanceolata indicate that technical innovations during the Bronze and Iron Age (e.g. metal ploughs, scythes, hay production, fertilising methods) gradually increased agricultural productivity. The successful adoption of yield-increasing advances cannot be explained by climatic determinism alone. Combined with archaeological evidence, our results suggest that despite considerable cycles of spatial and demographic reorganisation (repeated land abandonments and expansions, as well as large-scale migrations and population decreases), human societies were able to shift to lower subsistence levels without dramatic ruptures in material culture. However, our data imply that human societies were not able to compensate rapidly for harvest failures when climate deteriorated. Agriculture in marginal areas was abandoned, and spontaneous reforestations took place on abandoned land south and north of the Alps. Only when the climate changed again to drier and warmer conditions did a new wide-spread phase of forest clearances and field extensions occur, allowing the reoccupation of previously abandoned areas. Spatial distribution of cereal cultivation and growth requirements of Cerealia species suggest that increases in precipitation were far more decisive in driving crop failures over central and southern Europe than temperature decreases.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Although platinum-based drugs are widely used chemotherapeutics for cancer treatment, the determinants of tumor cell responsiveness remain poorly understood. We show that the loss of subunits LRRC8A and LRRC8D of the heteromeric LRRC8 volume-regulated anion channels (VRACs) increased resistance to clinically relevant cisplatin/carboplatin concentrations. Under isotonic conditions, about 50% of cisplatin uptake depended on LRRC8A and LRRC8D, but neither on LRRC8C nor on LRRC8E. Cell swelling strongly enhanced LRRC8-dependent cisplatin uptake, bolstering the notion that cisplatin enters cells through VRAC. LRRC8A disruption also suppressed drug-induced apoptosis independently from drug uptake, possibly by impairing VRAC-dependent apoptotic cell volume decrease. Hence, by mediating cisplatin uptake and facilitating apoptosis, VRAC plays a dual role in the cellular drug response. Incorporation of the LRRC8D subunit into VRAC substantially increased its permeability for cisplatin and the cellular osmolyte taurine, indicating that LRRC8 proteins form the channel pore. Our work suggests that LRRC8D-containing VRACs are crucial for cell volume regulation by an important organic osmolyte and may influence cisplatin/carboplatin responsiveness of tumors.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In transient expression studies after DNA transfection of HeLa cells, the mouse U7 gene produces only approximately 30% of the RNA produced by a mouse U1b gene. This difference persists even when the transfected genes have all their 5' and 3' flanking sequences exchanged suggesting a post-transcriptional effect. When the special U7 Sm binding site is mutated to a consensus derived from the major snRNAs (Sm-opt), the U7 RNA level increases 4- to 5-fold, whereas no RNA is detected from a U7 gene with a non-functional Sm binding site (Sm-mut). Moreover, U1b genes with the U7 Sm binding site yield reduced RNA levels. The Sm-opt site also alters the cellular behaviour of the corresponding U7 snRNA. It accumulates to a higher level in the nucleus than wild type U7 RNA, and is better immunoprecipitable with anti-Sm antibodies. Injection experiments in Xenopus oocytes indicate that the U7 genes with either Sm-opt or Sm-mut sites produce similar amounts of RNA as wild type U7, but that they differ in opposing ways in the processing of precursors to mature size U7 snRNA and in nuclear accumulation. However, in reconstitution experiments using Xenopus oocytes, we show that U7 Sm-opt RNA, despite its efficient nuclear accumulation, is not active in 3' processing of histone pre-mRNA, whereas wild type U7 RNA is assembled into functional snRNPs, which correctly process histone pre-mRNA substrate. This suggests a functional importance of the special U7 Sm sequence.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Histone RNA 3' end formation occurs through a specific cleavage reaction that requires, among other things, base-pairing interactions between a conserved spacer element in the pre-mRNA and the minor U7 snRNA present as U7 snRNP. An oligonucleotide complementary to the first 16 nucleotides of U7 RNA can be used to characterize U7 snRNPs from nuclear extracts by native gel electrophoresis. Using similar native gel techniques, we present direct biochemical evidence for a stable association between histone pre-mRNA and U7 snRNPs. Other complexes formed in the nuclear extract are dependent on the 5' cap structure and on the conserved hairpin element of histone pre-mRNA, respectively. However, in contrast to the U7-specific complex, their formation is not required for processing. Comparison of several authentic and mutant histone pre-mRNAs with different spacer sequences demonstrates that the formation and stability of the U7-specific complex closely follows the predicted stability of the potential RNA-RNA hybrid. However, this does not exclude a stabilization of the complex by U7 snRNP structural proteins.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND Ductal carcinoma in situ (DCIS) is a noninvasive breast lesion with uncertain risk for invasive progression. Usual care (UC) for DCIS consists of treatment upon diagnosis, thus potentially overtreating patients with low propensity for progression. One strategy to reduce overtreatment is active surveillance (AS), whereby DCIS is treated only upon detection of invasive disease. Our goal was to perform a quantitative evaluation of outcomes following an AS strategy for DCIS. METHODS Age-stratified, 10-year disease-specific cumulative mortality (DSCM) for AS was calculated using a computational risk projection model based upon published estimates for natural history parameters, and Surveillance, Epidemiology, and End Results data for outcomes. AS projections were compared with the DSCM for patients who received UC. To quantify the propagation of parameter uncertainty, a 95% projection range (PR) was computed, and sensitivity analyses were performed. RESULTS Under the assumption that AS cannot outperform UC, the projected median differences in 10-year DSCM between AS and UC when diagnosed at ages 40, 55, and 70 years were 2.6% (PR = 1.4%-5.1%), 1.5% (PR = 0.5%-3.5%), and 0.6% (PR = 0.0%-2.4), respectively. Corresponding median numbers of patients needed to treat to avert one breast cancer death were 38.3 (PR = 19.7-69.9), 67.3 (PR = 28.7-211.4), and 157.2 (PR = 41.1-3872.8), respectively. Sensitivity analyses showed that the parameter with greatest impact on DSCM was the probability of understaging invasive cancer at diagnosis. CONCLUSION AS could be a viable management strategy for carefully selected DCIS patients, particularly among older age groups and those with substantial competing mortality risks. The effectiveness of AS could be markedly improved by reducing the rate of understaging.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background The few studies that have evaluated syntax in autism spectrum disorder (ASD) have yielded conflicting findings: some suggest that once matched on mental age, ASD and typically developing controls do not differ for grammar, while others report that morphosyntactic deficits are independent of cognitive skills in ASD. There is a need for a better understanding of syntax in ASD and its relation to, or dissociation from, nonverbal abilities. Aims Syntax in ASD was assessed by evaluating subject and object relative clause comprehension in adolescents and adults diagnosed with ASD with a performance IQ within the normal range, and with or without a history of language delay. Methods & Procedures Twenty-eight participants with ASD (mean age 21.8) and 28 age-matched controls (mean age 22.07) were required to point to a character designated by relative clauses that varied in syntactic complexity. Outcomes & Results Scores indicate that participants with ASD regardless of the language development history perform significantly worse than age-matched controls with object relative clauses. In addition, participants with ASD with a history of language delay (diagnosed with high-functioning autism in the DSM-IV-TR) perform worse on subject relatives than ASD participants without language delay (diagnosed with Asperger syndrome in the DSM-IV-TR), suggesting that these two groups do not have equivalent linguistic abilities. Performance IQ has a positive impact on the success of the task for the population with ASD. Conclusions & Implications This study reveals subtle grammatical difficulties remaining in adult individuals with ASD within normal IQ range as compared with age-matched peers. Even in the absence of a history of language delay in childhood, the results suggest that a slight deficit may nevertheless be present and go undetected by standardized language assessments. Both groups with and without language delay have a similar global performance on relative clause comprehension; however, the study also indicates that the participants with reported language delay show more difficulty with subject relatives than the participants without language delay, suggesting the presence of differences in linguistic abilities between these subgroups of ASD.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A (1→3,1→4)‐β‐D‐glucan endohydrolase [(1→3,1→4)‐β‐glucanase, EC 3.2.1.73] was detected in wheat (Triticum aestivum L.) leaves by Western analyses and activity measurements. This enzyme is able to degrade the (1→3,1→4)‐β‐glucans present in the cell walls of cereals and other grass species. In wheat, enzyme levels clearly increased during leaf development, reaching maximum values at full expansion and then decreasing upon leaf ageing. To test whether the abundance of (1→3,1→4)‐β‐glucanase might be controlled by the carbohydrate status, environmental and nutritional conditions capable of altering the leaf soluble sugar contents were used. Both the activity and enzyme protein levels rapidly and markedly increased when mature leaves were depleted of sugars (e.g. during extended dark periods), whereas elevated carbohydrate contents (e.g. following continuous illumination, glucose supply in the dark or nitrogen deficiency during a light/dark cycle) caused a rapid decrease in (1→3,1→4)‐β‐glucanase abundance or prevented its accumulation in the leaves. The physiological significance of (1→3,1→4)‐β‐glucanase accumulation under sugar depletion remains to be elucidated.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In analogy to the [M(II)(bpy)(3)](2+) cations, where M(II) is a divalent transition-metal and bpy is 2,2'-bipyridine, the tris-chelated [M(III)(bpy)(3)](3+) cations, where M(III) is Cr(III) or Co(III), induce the crystallization of chiral, anionic three-dimensional (3D) coordination polymers of oxalate-bridged (&mgr;-ox) metal complexes with stoichiometries [M(II)(2)(ox)(3)](n)()(2)(n)()(-) or [M(I)M(III)(ox)(3)](n)()(2)(n)()(-). The tripositive charge is partially compensated by inclusion of additional complex anions like ClO(4)(-), BF(4)(-), or PF(6)(-) which are encapsulated in cubic shaped cavities formed by the bipyridine ligands of the cations. Thus, an elaborate structure of cationic and anionic species within a polymeric anionic network is realized. The compounds isolated and structurally characterized include [Cr(III)(bpy)(3)][ClO(4)] [NaCr(III)(ox)(3)] (1), [Cr(III)(bpy)(3)][ClO(4)][Mn(II)(2)(ox)(3)] (2), [Cr(III)(bpy)(3)][BF(4)] [Mn(II)(2)(ox)(3)] (3), [Co(III)(bpy)(3)][PF(6)][NaCr(III)(ox)(3)] (4). Crystal data: 1, cubic, P2(1)3, a = 15.523(4) Å, Z = 4; 2, cubic, P4(1)32, a = 15.564(3) Å, Z = 4; 3, cubic, P4(1)32, a = 15.553(3) Å, Z = 4; 4, cubic, P2(1)3, a = 15.515(3) Å, Z = 4. Furthermore, it seemed likely that 1,2-dithiooxalate (dto) could act as an alternative to the oxalate bridging ligand, and as a result the compound [Ni(II)(phen)(3)][NaCo(III)(dto)(3)].C(3)H(6)O (5) has successfully been isolated and structurally characterized. Crystal data: 5, orthorhombic, P2(1)2(1)2(1), a = 16.238(4) Å, b = 16.225(4) Å, c = 18.371(5) Å, Z = 4. In addition, the photophysical properties of compound 1 have been investigated in detail. In single crystal absorption spectra of [Cr(III)(bpy)(3)][ClO(4)][NaCr(III)(ox)(3)] (1), the spin-flip transitions of both the [Cr(bpy)(3)](3+) and the [Cr(ox)(3)](3)(-) chromophores are observed and can be clearly distinguished. Irradiating into the spin-allowed (4)A(2) --> (4)T(2) absorption band of [Cr(ox)(3)](3)(-) results in intense luminescence from the (2)E state of [Cr(bpy)(3)](3+) as a result of rapid energy transfer processes.