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11.
Urs Fischbacher 《Journal of mathematical biology》1996,34(8):926-936
As an alternative to dichotomous keys, tabular keys are used for taxonomic identification. With the use of computers, keys based on the Bayes formula can also be made available more widely. For the development of a key, the maximum a posterior probability (MAP) for a taxon is important because it allows to evaluate the quality of a key. If it is low, the taxon is hard to distinguish from other taxa. In this paper, we show that finding MAP in a Bayesian key is NP-hard. Estimates for MAP or other measures have to be used for the estimation of the quality of a Bayesian key. 相似文献
12.
Urs Thalmann Thomas Geissmann Arsène Simona Thomas Mutschler 《International journal of primatology》1993,14(3):357-381
During a short field trip to the Special Reserve of Anjanaharibe-Sud in northeastern Madagascar, data concerning pelage coloration, behavior (especially vocalization), and ecology of indris were collected. Anjanaharibe-Sud is the northernmost locality of indri distribution. In comparison to the better-known indris from the southern part of their distribution, the indris in this region show different pelage coloration. Several types of loud vocalizations are analyzed, based on a small sample of tape recordings. Their song structure is more complicated than previously reported, containing distinct sequences of duetting. Data on behavior and ecology were collected by interviewing guides and local inhabitants. Some information contrasts with reports on the more southern indri populations. The conservation status of indris in Anjanaharibe-Sud and the future of the reserve are outlined. 相似文献
13.
Kinetics of microbial growth with mixtures of carbon sources 总被引:11,自引:0,他引:11
14.
Distribution of glycosylphosphatidylinositol-specific phospholipase D mRNA in bovine tissue sections
It has been reported that mammalian serum, and to a lower extent mammalian liver, brain, pancreas, udder, and milk, contain glycosylphosphatidylinositolspecific phospholipase D activity. However, the sites of synthesis have not been determined. In order to study in which cells(s) of the organism synthesis of glycosylphosphatidylinositol-specific phospholipase D takes place, we undertook a systematic screening of 12 different bovine tissues. In situ hybridization experiments with a specific anti-sense RNA probe, derived from a bovine liver cDNA, revealed that glycosylphosphatidylinositol-specific phospholipase D mRNA is present in mast cells of the adrenal gland, lung, and liver. On the other hand, our specific probe detected no mRNA in bovine pancreas, brain, and udder, although enzyme activity has been reported in these tissues. Northern blot analysis of total bovine liver RNA demonstrated two distinct glycosylphosphatidylinositol-specific phospholipse D mRNAs of approximately 3.3 kb and 4 kb length suggesting that two forms of the enzyme may exist. 相似文献
15.
16.
Urs M. Weber 《Trees - Structure and Function》1997,11(5):277-290
Outbreaks of the larch budmoth (LBM) (Zeiraphera diniana) recur cyclically approximately every 7 to 10 years in subalpine larch-cembran pine and montane to subalpine larch-Norway
spruce forests of the relatively dry valleys of the European Alps. By dendroecologically analyzing increment cores from 570
host (European larch –Larix decidua) and non-host trees (cembran pine –Pinus cembra, Norway spruce –Picea abies) through the use of skeleton plots, at least 57 (59) outbreaks could be reconstructed in the optimum Upper Engadine Valley
(suboptimum Goms Valley), Switzerland, during the time period 1503 (1472) to 1990. The average interval between initial years
of successive outbreaks was 8.58 (8.95) years, SD 1.66 (2.13) years. Over the centuries spatial shifts of LBM activity between
the two study areas occurred, probably due to climatic changes. Clear, site-specific differences in LBM attack could only
be found in the suboptimum area where high-lying (>1800 m) and/or south-facing stands were infested most. LBM-afflicted trees
proved to be unsuitable for climate reconstructions because the impact of the persistently recurring outbreaks on tree growth
is dominant. In order to provide sufficient information for a detailed ecological interpretation of the course of an outbreak,
latewood widths and/or densities have to be analyzed in addition to the ring-widths.
Received: 11 February 1995 / Accepted: 19 July 1996 相似文献
17.
Usha K. Urs David J. Sharkey Thomas S. Peat Wayne A. Hendrickson H. M. Krishna Murthy 《Proteins》1995,23(1):111-114
Thermus aquaticus DNA polymerase I is an enzyme that is of both physiological and technological interest. It carries out template-directed polymerization of DNA at elevated temperatures and is widely used in polymerase chain reaction (PCR). We have obtained crystals of the enzyme that diffracts X-rays to at least 3.0 Å resolution in a cubic space group. Determination of the three-dimensional structure of the native enzyme along with those of relevant complexes will greatly enhance our knowledge of molecular events involved in DNA replication, will permit improvements in PCR, and will add to our knowledge of the structural bases of thermo stability in proteins. © 1995 Wiley-Liss, Inc. 相似文献
18.
Is hydrogen peroxide a second messenger of salicylic acid in systemic acquired resistance? 总被引:18,自引:1,他引:17
Urs Neuenschwander Bernard Vernooij Leslie Friedrich Scott Uknes Helmut Kessmann John Ryals 《The Plant journal : for cell and molecular biology》1995,8(2):227-233
Elevated levels of salicylic acid (SA) are required for the induction of systemic acquired resistance (SAR) in plants. Recently, a salicylic acid-binding protein (SABP) isolated from tobacco was shown to have catalase activity. Based on this finding elevated levels of hydrogen peroxide (H2 O2 ) were postulated to act as a second messenger of SA in the SAR signal transduction pathway. A series of experiments have been carried out to clarify the role of H2 O2 in SAR-signaling. No increase of H2 O2 was found during the onset of SAR. Induction of the SAR gene, PR-1, by H2 O2 and H2 O2 -inducing chemicals is strongly suppressed in transgenic tobacco plants that express the bacterial salicylate hydroxylase gene, indicating that H2 O2 induction of SAR genes is dependent on SA accumulation. Following treatment of plants with increasing concentrations of H2 O2 , a dose-dependent accumulation of total SA species was found, suggesting that H2 O2 may induce PR-1 gene expression through SA accumulation. While the results do not support a role for H2 O2 in SAR signaling, it is suggested that SA inhibition of catalase activity may be important in tissues undergoing a hypersensitive response. 相似文献
19.
An assay for arginase is described that uses l-[guanido-14C]arginine as substrate. Unhydrolyzed arginine is removed in a batch procedure with sulfonate resin and the [14C]urea product is determined quantitatively in the resin supernatant. The assay requires 5 min and is performed in one tube. The sensitivity is approximately 0.1 munits of arginase. Arginase activities in fetal calf serum and in murine macrophage extract have been determined and the bovine liver enzyme has been used as a reference. 相似文献
20.
Aminopeptidase, carboxypeptidase and neutral endopeptidase activitieswere analyzed in glumes and in kernels of field-grown wheat(Triticum aestivum L.) during ear development. Kernels harvestedon two dates were subdivided into outer pericarp, cross cells,endosperm and embryo. In developing parts with a net nitrogeninflux (young glumes, embryo, endosperm) the aminopeptidaseactivity is high, but in nitrogen-mobilizing tissues (senescingglumes, Outer pericarp) this activity decreases. Carboxypeptidaseis most active in fully expanded tissues. Neutral endopeptidaseshows the highest activity in the nitrogen mobilizing partsand extremely low activity in the embryo and the endosperm. (Received July 15, 1978; ) 相似文献