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701.
The literature supports a positive correlation between pollen size and style length and that pollen size may be affected by
a trade-off with pollen number. A correlation between pollen size and pollinator type has been hypothesized by some authors
but not confirmed. To assess these associations, pollen grain number, pollen grain diameter and style length were measured
in 53 species of Caryophylloideae that had been classified beforehand as being diurnal, nocturnal or self-pollinated. Surprisingly,
many species showed two, and a few even three, distinct pollen grain size classes per individual anther. Therefore, further
analyses were based on the different pollen size classes and respective pollen grain numbers. Firstly, we found no indication
of a trade-off between pollen size and number. Secondly, a positive linear correlation between style length and pollen grain
diameter was found using conventional analysis methods and phylogenetically independent contrasts. Thirdly, when using conventional
analysis methods a strong relationship between style length and pollination mode was found, with nocturnal species having
significantly longer styles and larger pollen grains than diurnal and selfing species. These results were not supported, however,
when calculating comparisons of phylogenetically independent pairs. We discuss our findings in relation to intra-specific
pollen polymorphism and pollen degeneration, both of which have been associated with different pollen grain sizes in Caryophylloideae.
Furthermore, we discuss the possibility that pollen polymorphism might be a mixed strategy to optimise the success of pollen
grains deposited at different pollen–ovule distances on long styles. 相似文献
702.
Annette Kopp‐Schneider Manuel Wiesenfarth Ruth Witt Dominic Edelmann Olaf Witt Ulrich Abel 《Biometrical journal. Biometrische Zeitschrift》2019,61(3):488-502
A multistage single arm phase II trial with binary endpoint is considered. Bayesian posterior probabilities are used to monitor futility in interim analyses and efficacy in the final analysis. For a beta‐binomial model, decision rules based on Bayesian posterior probabilities are converted to “traditional” decision rules in terms of number of responders among patients observed so far. Analytical derivations are given for the probability of stopping for futility and for the probability to declare efficacy. A workflow is presented on how to select the parameters specifying the Bayesian design, and the operating characteristics of the design are investigated. It is outlined how the presented approach can be transferred to statistical models other than the beta‐binomial model. 相似文献
703.
M H Tadros F Suter H H Seydewitz I Witt H Zuber G Drews 《European journal of biochemistry》1984,138(1):209-212
The small bacteriochlorophyll-binding polypeptide of the light-harvesting complex B870 was extracted from the intracytoplasmic membrane of the strain A1a+ of Rhodopseudomonas capsulata with chloroform/methanol/ammonium acetate and separated by chromatography on Sephadex LH60 using the same solvent. The polypeptide obtained from the peak fraction III was found to be homogeneous and identical with the small polypeptide isolated from the B870 complex as shown by dodecyl sulfate/polyacrylamide gel electrophoresis, amino acid composition and N-terminal sequence. The complete amino acid sequence is given. The relative molecular mass based on the amino acid sequence is 5341. The polarity of amino acids is 35.42%. The C-terminal part of the peptide chain from residue 29 to 48 is hydrophobic and includes one His residue. 相似文献
704.
Prevalence, risk factors and rheological profile of arterial vascular disease; first results of the Aachen study 总被引:1,自引:0,他引:1
H Kiesewetter F Jung G Kotitschke H P Nüttgens R Witt C Winkelhog K H Ladwig E Waterloh P Roebruck R Schneider 《Folia haematologica (Leipzig, Germany : 1928)》1988,115(4):587-593
During a prospective cohort-study of several year's duration the results of a survey regarding prevalence of arterial occlusive disease, as well as classical risk factors and rheological profile of patients suffering from vascular disease were examined. 364 patients out of a total of 2,498 individuals suffered from vascular disease. 168 (6.7%) had cardiovascular, 151 (6.0%) cerebrovascular and 109 (4.4%) peripheral vascular disease. Compared to to healthy individuals, the patients showed a significant accumulation of classical risk factors (elevated cholesterol and triglyceride values, decreased HDL-cholesterol concentration, obesity, smoking, high blood pressure, gout or diabetes mellitus). Only 30.2% of the healthy controls presented two or more risk factors, whereas the angiological patients showed two or more risk factors in 71.9%. Rheological parameters measured in the survey were: Plasma viscosity, erythrocyte and platelet aggregation, erythrocyte rigidity and hematocrit. Only 14.2% of the healthy individuals had two or more rheological parameters exceeding the 1-s range, whereas 56.6% of the patients showed two or more elevated rheological parameters. 相似文献
705.
706.
A variation of the Coomassie dye-binding assay for proteins is described. Protein samples were pipetted to the surface of agarose plates in uniformly sized spots and stained with Coomassie Blue G-250. The bound dye was determined by densitometric scanning using double wavelength and flying spot facilities. The response curves were linear in an about 10-fold concentration range with a lower detection limit of 0.5 microgram. No background correction was necessary because unbound dye and most substances known to interfere with other protein assays were removed during the staining and destaining of the agarose gels. Membrane proteins could be analyzed since the samples were applied as solutions in 1% sodium dodecyl sulfate. 相似文献
707.
G. Bradd Witt Lindi J. Berghammer Robert J. S. Beeton Eugene J. Moll 《Austral ecology》2000,25(3):260-267
This paper explores the potential of a new method of reconstructing historical vegetation change in the Australian rangelands. Historical monitoring of rangeland vegetation has been so deficient that it is not possible to determine whether a long‐term trend toward degradation has occurred (as is often assumed) or, indeed, if it is continuing to occur. Because long‐term records are unavailable any attempt to monitor vegetation retrospectively must be based on proxy measures rather than direct observation. Where historical data are lacking an integration of palaeoecological, archaeological and ecological methods is required to reconstruct the past. Our research is based on a detailed analysis of sheep faeces deposited near a shearing shed in the semiarid rangelands of south‐west Queensland between the late 1930s and the mid‐1990s. The faeces in these deposits represent the diet of sheep in the days leading up to the property’s annual shearing and as such are a potentially useful index to changes in vegetation. Results indicate significant changes in the diet of sheep since the late 1940s. The potential of this method, and its limitations, are discussed. Long‐term records are critical in understanding issues of sustainability in land management and it is intended that this paper will stimulate further research into historical vegetation change in rangelands. 相似文献
708.
E. Schulze Martin Witt M. Kasper Clemens W. G. M. Löwik Richard H. W. Funk 《Histochemistry and cell biology》1999,111(1):61-69
Until now, many extracellular matrix proteins, e.g. osteopontin and osteonectin, have been used to determine a cell’s osteogenic
maturation. The disadvantage in evaluation of these proteins is their relative wide-ranging appearance throughout the osteogenic
differentiation process. Thus, the aim of this study was to establish an immunohistochemical setup using E11, a marker that
binds selectively to cells of the late osteogenic cell lineage. In addition, the histochemical expression of the bone matrix
proteins osteonectin, osteopontin and fibronectin was compared to that of E11 using monoclonal antibodies. For light microscopical
detection of osteogenic markers in cultured cells we developed a simple paraffin technique using a fibrin glue as embedding
medium. This allows the handling of cultured cells such as a tissue sample and includes the use of stored biological specimens
for further immunohistochemical experiments. We used newborn rat calvariae for whole tissue preparations and for isolation
and cultivation of bone cells. In addition, we included the rat osteosarcoma cell line ROS 17/2.8 in this study. For the first
time, we have localised E11 in osteocytes of rat calvaria preparations at the electron microscopical level. E11 was detected
at plasma membranes of osteocytes and their processes, but not at those of osteoblasts. Accompanying experiments with cultured
newborn rat calvaria cells and ROS 17/2.8 cells revealed E11 reactivity on a subset of cells. The results obtained confirm
the suitability of the differentiation marker E11 as a sensitive instrument for the characterisation of bone cell culture
systems.
Accepted: 25 August 1998 相似文献
709.
B. J. Trask Heather Mefford Ger van den Engh Hillary F. Massa Ramesh C. Juyal Lorraine Potocki Brenda Finucane Dianne N. Abuelo David R. Witt Ellen Magenis Antonio Baldini Frank Greenberg James R. Lupski P. I. Patel 《Human genetics》1996,98(6):710-718
We have used bivariate flow karyotyping to quantify the deletions involving chromosome 17 in sixteen patients with Smith-Magenis
syndrome (SMS). The fluorescence intensities of mitotic chromosomes stained with Hoechst 33258 and chromomycin were quantified
in a dual-beam flow cytometer. For each patient, the position of the peak representing the deleted chromosome 17 was compared
to those of the normal homologs of an unaffected parent. The patients could be classified into four groups based on the size
of their deletions. The deletions ranged from ∼9–10 Mb (∼10–11% of the chromosome) to below the detection limit of the technique
(2 Mb). Different deletion sizes were detected among patients whose high-resolution banding results were similar. Some deletions
detected by banding were not detected by flow analyses. Deletion estimates are largely consistent with the results of molecular
analyses. Patients with larger deletions that extend into band 17p12 have abnormal electrophysiologic studies of peripheral
nerves. Deletion size does not appear to correlate with the degree of mental retardation, presence of behavioral abnormalities,
craniofacial anomalies or common skeletal findings in SMS. By identifying patients with varying deletion sizes, these data
will aid the construction of a long-range deletion-based map of 17p11.2 and identification of the genes involved in this syndrome.
Received: 19 March 1996 / Revised: 21 June 1996 相似文献
710.