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1.
Abstract. Nutrient conservation in vegetation affects rates of litter decomposition and soil nutrient availability. Although resorption has been traditionally considered one of the most important plant strategies to conserve nutrients in temperate forests, long leaf life‐span and low nutrient requirements have been postulated as better indicators. We aimed at identifying nutrient conservation strategies within characteristic functional groups of NW Patagonian forests on Andisols. We analysed C‐, N‐, P‐, K‐ and lignin‐concentrations in mature and senescent leaves of ten native woody species within the functional groups: broad‐leaved deciduous species, broad‐leaved evergreens and conifers. We also examined mycorrhizal associations in all species. Nutrient concentration in mature leaves and N‐ resorption were higher in broad‐leaved deciduous species than in the other two functional groups. Conifers had low mature leaf nutrient concentrations, low N‐resorption and high lignin/N ratios in senescent leaves. P‐ and K‐resorptions did not differ among functional groups. Broad‐leaved evergreens exhibited a species‐dependent response. Nitrogen in mature leaves was positively correlated with both N resorption and soil N‐fertility. Despite the high P‐retention capacity of Andisols, N appeared to be the more limiting nutrient, with most species being proficient in resorbing N but not P. The presence of endomycorrhizae in all conifers and the broad‐leaved evergreen Maytenus boaria, ectomycorrhizae in all Nothofagus species (four deciduous, one evergreen), and cluster roots in the broad‐leaved evergreen Lomatia hirsuta, would be possibly explaining why P is less limiting than N in these forests. 相似文献
2.
The autoactivation of factor XII (Hageman factor) induced by low-Mr heparin and dextran sulphate. The effect of the Mr of the activating polyanion. 总被引:1,自引:0,他引:1 下载免费PDF全文
Human Factor XII is known to undergo autoactivation in the presence of dextran sulphate of Mr 500,000. We have now studied the dependence of this reaction on the Mr of the dextran sulphate by using fractions resolved by gel filtration. We have found that autoactivation can be induced by dextran sulphate fractions with Mr as low as 3000, and there is a marked dependence of the rate constant of autoactivation on the Mr value. Fractions with Mr below 8000 gave very low rates of autoactivation; there was a sharp increase in the rate obtained when the Mr of the dextran sulphate was greater than 10,000. Various preparations of heparin were also able to support the autoactivation of Factor XII and gave a very similar relationship between molecular size and reaction rate. The data provide support for the hypothesis that the mechanism by which the 'surface' acts in contact activation involves the presence, on the same particle, of multiple binding sites for the proteins. 相似文献
3.
Experimental designs that include repeated measures of binary response variables over time and under different conditions are common in biology. In such settings, it is often desirable to characterize the response pattern over time. When response variables are continuous, this characterization can be made in terms of a growth model such as the Potthoff-Roy growth curve model. We illustrate how a similar growth curve modeling strategy can be implemented using weighted least squares (WLS) methods for binary response data. The growth models are constructed in terms of polynomial functions across marginal response. However, when growth models are fit to repeated binary response, the nonsignificant higher-order polynomial functions are dropped from the model, rather than used as covariates. Dropping the nonsignificant polynomials from the model will reduce the number of response functions, and help avoid small-sample problems that can occur when the number of correlated response functions is large and sample sizes are small. The reduced set of response functions are then modeled using WLS methods. We illustrate such models with an example of binary fly oviposition response (accept or reject) exhibited by two populations of flies at four ages to two types of fruit. 相似文献
4.
MATCH-UP/MATRIX is a program designed to aid the investigatorinterested in determining primary protein structure. It is writtenin Applesoft BASIC for the Apple lle microcomputer. MATCH-UPwill survey any set of proteinaceous materials for amino acidsequence homology; however, it is primarily intended to comparethe structures of newly sequenced peptides with the establishedstructure of a protein with suspected homology. Any peptide-to-proteinalignment which shows a homology greater than or equal to thepercentage specified by the user will result in output. MATRIXwill compare the sequences of two proteins (peptides) in whateveralignment specified by the user and is intended to spot insertionsand/or deletions between structures.
Received on December 2, 1985; accepted on March 10, 1986 相似文献
5.
Peter Diehl und Hans-Wolfgang Helb 《Journal of Ornithology》1985,126(3):281-286
Zusammenfassung Bei einem Amsel- (Turdus merula) gelang es erstmals, während des Singens (Subsong) radiotelemetrisch die Herzfrequenz (HR) zu messen. Gegenüber der Ruhe-Herzfrequenz (R-HR) erhöhte sich die HR während 4 Gesangsphasen um 33–72 %. In den Gesangspausen und nach Beendigung des Singens fiel die HR innerhalb von 6–8 s auf Werte, die um 15–20 % über der Ruhe-HR lagen. Der aus entspannter Situation heraus erfolgende Subsong stellt eine physiologische Belastung für den Vogel dar, die seine Einstufung als unbeschwert oder gar funktionslos unwahrscheinlich macht.
Prof. Dr. Erwin Tretzel zum 65. Geburtstag 相似文献
Bird song and heart rate — radiotelemetry measurements to the subsong on Blackbird (Turdus merula)
Summary On a male Blackbird (Turdus merula), heart rate during the bird's singing (subsong) was measured by means of radiotelemetry. As compared to its resting values (R-HR) heart rate (HR) increased by 33–72 % during 4 phases of singing. When singing was interrupted HR decreased again within 6–8 s down to values which were still about 15–20 % above R-HR. Though subsong was uttered in an apparently relaxed situation it seemed to be to a certain degree straining for the bird. Hence subsong should not be regarded as a behaviour pattern free of stress or function.
Prof. Dr. Erwin Tretzel zum 65. Geburtstag 相似文献
6.
Locus Heterogeneity for Waardenburg Syndrome is Predictive of Clinical Subtypes 总被引:1,自引:4,他引:1 下载免费PDF全文
Lindsay A. Farrer Kathleen S. Arnos James H. Asher Clinton T. Baldwin Scott R. Diehl Thomas B. Friedman Jacquie Greenberg Kenneth M. Grundfast Christopher Hoth Anil K. Lalwani Barbara Landa Kate Leverton Aubrey Milunsky Robert Morell Walter E. Nance Valerie Newton Rajkumar Ramesar Valluri S. Rao Jennifer E. Reynolds Theresa B. San Agustin Edward R. Wilcox Ingrid Winship Andrew P. Read 《American journal of human genetics》1994,55(4):728-737
Waardenburg syndrome (WS) is a dominantly inherited and clinically variable syndrome of deafness, pigmentary changes, and distinctive facial features. Clinically, WS type I (WS1) is differentiated from WS type II (WS2) by the high frequency of dystopia canthorum in the family. In some families, WS is caused by mutations in the PAX3 gene on chromosome 2q. We have typed microsatellite markers within and flanking PAX3 in 41 WS1 kindreds and 26 WS2 kindreds in order to estimate the proportion of families with probable mutations in PAX3 and to study the relationship between phenotypic and genotypic heterogeneity. Evaluation of heterogeneity in location scores obtained by multilocus analysis indicated that WS is linked to PAX3 in 60% of all WS families and in 100% of WS1 families. None of the WS2 families were linked. In those families in which equivocal lod scores (between −2 and +1) were found, PAX3 mutations have been identified in 5 of the 15 WS1 families but in none of the 4 WS2 families. Although preliminary studies do not suggest any association between the phenotype and the molecular pathology in 20 families with known PAX3 mutations and in four patients with chromosomal abnormalities in the vicinity of PAX3, the presence of dystopia in multiple family members is a reliable indicator for identifying families likely to have a defect in PAX3. 相似文献
7.
Comparative Study of Cultured Burkitt Tumor Cells by Immunofluorescence, Autoradiography, and Electron Microscopy 总被引:7,自引:6,他引:7 下载免费PDF全文
Harald Zur Hausen Werner Henle Klaus Hummeler Volker Diehl Gertrude Henle 《Journal of virology》1967,1(4):830-837
Cultured Burkitt cells were examined by immunofluorescence, autoradiography, and electron microscopy in an effort to identify the stainable cells with those harboring herpes-type virus particles. Immediately after a 2-hr pulse of (3)H-thymidine, from 30 to 60% of the cells revealed heavy nuclear labeling. In most cases the grains were evenly dispersed, but in about 3 to 5% the grains showed a focal distribution and occasionally they extended into the cytoplasm. Such nuclear foci were rarely seen at 8 hr after the pulse. When the analysis was restricted to preselected immunofluorescent cells, up to 80% showed label at 8 hr and cytoplasmic grains were prominent. To reduce cellular deoxyribonucleic acid (DNA) synthesis, cells were X-irradiated with 3,000 to 6,000 R, and the isotope pulse was applied 1, 4, or 7 days later. Whereas the total number of labeled cells decreased in roughly twofold steps at the respective intervals (from 40 to 10%), the incorporation of (3)H-thymidine into fluorescent cells was not affected by X irradiation. In each series, about 70% of the fluorescent cells contained label when they were examined at 24 and 48 hr after the pulse, whereas at 8 and 72 hr fewer were positive. At the earlier intervals, unlabeled fluorescent cells most likely represented cells which had completed viral DNA synthesis prior to the pulse; at the later intervals, unlabeled fluorescent cells were probably cells which commenced viral replication after the pulse. These data support the conclusion that the immunofluorescent cells are the ones which harbor virus, and also confirm the expectation that the virus is a DNA virus from a member of the herpes group. This conclusion was firmly established by sectioning and electron microscopic examination of individual fluorescent cells, all of which contained numerous virus particles, whereas the nonstained cells prepared in a similar manner were free of them. 相似文献
8.
9.
Jessel R Haertel S Socaciu C Tykhonova S Diehl HA 《Journal of cellular and molecular medicine》2002,6(1):82-92
We investigated the time-dependence of apoptotic events in EL4 cells by monitoring plasma membrane changes in correlation to DNA fragmentation and cell shrinkage. We applied three apoptosis inducers (staurosporine, tubericidine and X-rays) and we looked at various markers to follow the early-to-late apoptotic events: phospholipid translocation (identified through annexin V-fluorescein assay and propidium iodide), lipid package (via merocyanine assay), membrane fluidity and anisotropy (via fluorescent measurements), DNA fragmentation by the fluorescence-labeling test and cell size measurements. The different apoptotic inducers caused different reactions of the cells: staurosporine induced apoptosis most rapidly in a high number of cells, tubercidine triggered apoptosis only in the S phase cells, while X-rays caused a G2/M arrest and subsequently apoptosis. Loss of lipid asymmetry is promptly detectable after one hour of incubation time. The phosphatidylserine translocation, decrease of lipid package and anisotropy, and the increase of membrane fluidity appeared to be based on the same process of lipid asymmetry loss. Therefore, the DNA fragmentation and the cell shrinkage appear to be parallel and independent processes running on different time scales but which are kinetically inter-related. The results indicate different signal steps to apoptosis dependent on inducer characteristics but the kinetics of "early-to-late" apoptosis appears to be a fixed program. 相似文献
10.
Christoph?ScheichEmail author Dietmar?Leitner Volker?Sievert Martina?Leidert Brigitte?Schlegel Bernd?Simon Ivica?Letunic Konrad?Büssow Anne?Diehl 《BMC structural biology》2004,4(1):4