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61.
Andrea Lami Aldo Marchetto Piero Guilizzoni Anselma Giorgis Julieta Masaferro 《Hydrobiologia》1994,274(1-3):57-64
Stratigraphic analyses of organic carbon, organic nitrogen and algal and bacterial carotenoids in short cores of profundal
sediments of four alpine lakes (Tovel, Leit, Paione superiore and Tom) were used to reconstruct their trophic history. In
addition, depth distribution of carbonaceous particle concentrations provided information on lake contamination from atmospheric
deposition.
In three lakes (Tovel, Leit and Tom), sedimentary carotenoids unique to sulfur photosynthetic bacteria (okenone and isorenieratene)
provide evidence of changes in the oxygen, light and sulfide conditions in the water column. All the lakes are oligotrophic
or moderately productive, and the algal community is dominated by Chlorophyta, Pyrrhophyta and Cryptophyta. Cyanobacteria
are rather poorly represented.
The steep increase of carbonaceous particles in the uppermost sediment layers of all the lakes suggests that lake contamination
by atmospheric transport of pollutants began in the 1940s to 1950s. These data, coupled with those from a parallel study on
Chrysophycean scale-inferred pH, indicate recent acidification in those which are poorly buffered (Paione superiore and Leit). 相似文献
62.
Andrea Timcke und Hans-Heiner Bergmann 《Journal of Ornithology》1994,135(1):95-100
Zusammenfassung Der Verbeugungstriller männlicher Brandenten, eine epigame Lautäußerung, weist sowohl in syntaktischen wie auch phonetischen Parametern zyklische jahreszeitliche Veränderungen auf. Die Gesamtdauer der Lautäußerung vergrößert sich allmählich im Laufe des Frühjahrs. Dafür sind eine Verlängerung des tonalen Eingangselements und eine Vermehrung der Elemente der abschließenden Phrase verantwortlich. Dagegen verkürzt sich das 2. Element gleichzeitig. In allen untersuchten Elementen erhöht sich die Tonhöhe parallel zur Verlängerung des Rufes. Diese Veränderungen des Ausdrucksverhaltens geben vermutlich Änderungen innerer Zustandsgrößen wieder.
Seasonally changing bird call: the trill call of male Shelducks (Tadorna tadorna)
Both syntactic and phonetic features of the trill call accompanying the whistle-shake in adult male Shelducks are subject to cyclic annual changes. In the course of spring, the duration of the whole call increases gradually. This is caused by a prolongation of the first call element and insertion of additive elements in the final phrase. In contrast the second element is shortened by about 10 ms. At the same time, the pitch of all measured elements is raised. These findings are discussed in the framework of hormonal regulation and communicative function.相似文献
63.
Subunits of forming pollen exine and Ubisch bodies as seen in freeze substitutedLedebouria socialis Roth (Hyacinthaceae) 总被引:1,自引:0,他引:1
Summary High-pressure freezing/freeze substitution/TEM was employed to investigate anthers of the monocotyledonous angiospermLedebouria socialis Roth (Hyacinthaceae) during early tetrad stage. The initials of the outer sporopollenous pollen wall stratum (=sexine) and of the homologous tapetal products (=Ubisch bodies) are composed of highly regular subunits: clustered globules with a constant diameter of approximately 28 nm. The clusters develop within diffuse accumulations of electron-dense material. This process, interpreted as sporopollenin polymerization, does not necessarily depend on the presence of membrane-bound enzymes. Immunogold labeling with JIM 5 and JIM 7 antibodies revealed that the primexine as well as the dissolving tapetal cell walls, the sites of sexine and Ubisch body formation, respectively, contain un-esterified and methyl-esterified pectins.Abbreviations E-PTA
ethanolic phosphotungstic acid
- PA
periodic acid
- UA/Pb
uranyl acetate/lead 相似文献
64.
Silvia Sartoris Andrea De Lerma Barbaro Tiziana Cestari Giuseppe Tridente Roberto S. Accolla 《Immunogenetics》1994,39(1):8-14
RJ 2.2.5 is a human B cell mutant, derived from Raji cells, which has lost expression of major histocompatibility complex (MHC) class II genes because of a defect in the AIR1 locus function. The MHC class II-positive phenotype can be restored by introducing an active AIR1 locus or its mouse equivalent, Air-1. An example of the latter is the H4 cell hybrid, derived by somatic cell fusion between RJ 2.2.5 and mouse class II-positive spleen cells. H4 contains a single mouse chromosome, autosome 16, in which the Air-1 locus maps, and an entire RJ 2.2.5-derived genome. In the present study we show that the physiologic target of the Air-1 locus product is contained within a limited HLA-DRA promoter sequence of 300 base pairs, encompassing the crucial Y, X, and W cis-acting elements. A plasmid construct, pDRA300neo, containing the HLA-DRA promoter sequence which drives the expression of the neomycin resistance gene, has been stably integrated in the genome of the H4 hybrid. Transfectants selected in the presence of G418 retain mouse chromosome 16 and express the DR genes. On the other hand, transfectants grown in a non-selective medium segregate mouse chromosome 16; this is accompanied by a loss of DRA gene expression and G418 resistance, although pDRA300neo is still integrated in the genome. These results offer scope for using this experimental model to clone the Air-1 gene in a straightforward way.
Correspondence to: R. S. Accolla. 相似文献
65.
Andrea Hoffman Ursula Halfter Peter-Christian Morris 《Plant Cell, Tissue and Organ Culture》1994,36(1):53-58
Conditions for maximising transient expression of GUS in leaf mesophyll protoplasts of Arabidopsis thaliana ecotype C24 were investigated. It was found that the factors most influencing expression levels, with optimum levels in parenthesis, were plasmid DNA quantity (100 g per 5 × 105 protoplasts), inclusion of carrier DNA (50 g), PEG pH and amount (pH above 6, and total PEG concentration at least 9% w/w) and the topological form of the DNA. Linearised plasmid DNA with long flanking sequences 3 and 5 to the marker gene yielded the highest levels of GUS expression.Abbreviations 2,4-d
2,4-dichlorophenoxyacetic acid
- GUS
-glucuronidase
- MU
methylumbelliferone
- PEG
polyethylene glycol
- X-gluc
5-bromo-4-chloro-3-indolyl--glucuronic acid 相似文献
66.
Daniele Morelli Alessandro Sardini Elena Villa Maria Luisa Villa Sylvie Ménard Maria I. Colnaghi Andrea Balsari 《Cancer immunology, immunotherapy : CII》1994,38(3):171-177
A hybrid hybridoma secreting a bispecific hybrid mAb (bsmAb), which recognizes both the epidermal growth factor receptor (EGF-R) and the drug doxorubicin, was produced by somatic hybridization of two hybridomas. The bsmAb obtained was able to retarget doxorubicin cytotoxicity in vitro specifically on EGF-R-positive cells exerting at the same time an antidotal effect on cells that did not overexpress the EGF-R. Distribution studies in mice indicate that the bsmAb selectively delivers the drug to tumour cells and modifies doxorubicin biodistribution with a statistically significant decrease of drug concentration in the intestine, which is the main target of early anthracycline toxicity. In keeping with this finding is the remarkable antidotal activity exerted by bsmAb in mice treated with doxorubiein, which is proved by retardation in loss of body weight and mortality. The effectiveness on tumour growth of the mAb followed by the administration of doxorubicin appears to be equal to that of the drug alone; however, the bsmAb exerts a remarkable antidotal activity. 相似文献
67.
68.
Zhu Yao Akinori Kimura Klaus Hartung Peter J. Haas Andrea Volgger Günter Brünnler Jürgen Bönisch Ekkehard D. Albert 《Immunogenetics》1993,38(6):421-429
We have investigated the DNA polymorphism for the DQA1 promoter region (QAP) and HLA-class II DRB1, DQA1, and DQB1 genes in 178 central European patients with Systemic lupus erythematosus (SLE) using polymerase chain reaction and Dig-ddUTP labeled oligonucleotides. Increased frequencies of DRB1*02 and *03 are confirmed by DNA typing. In addition, the frequencies of DQA1*0501, *0102 and DQB1*0201, *0602 alleles are increased in the patients as compared to controls. The strongest association to SLE is found with DRB1*03 and DQB1*0201 alleles (p<10–7, p corr. <10–5 and p<10–6, p corr. <10–4, respectively). By investigating the DQA1 promoter region in the SLE patients we have detected nine different QAP variants. Increased frequencies of QAP1.2 and QAP4.1 are observed in patients as compared to controls (p <0.05, p corr. = n. s.). Analysis of linkage disquilibria demonstrates a very strong association between QAP variants and DQA1, DRB1 alleles. Certain QAP variants are completely associated with DQA1 and DRB1 alleles, whereas others can combine with different DQA1 and DRB1 alleles. All DRB1*02-positive patients and controls carry QAP1.2, and all DRB1*03-positive patients and controls carry QAP4.1. Conversely, the QAP1.2 variant appears only in DRB1*02 haplotypes, while the QAP4.1 variant can be observed in DRB1*03, *11, and *1303 haplotypes. Based on the strong linkage disequilibria between DRB1-DQA1-DQB1 genes and between DRB1-QAP-DQA1, we have deduced the four-point haplotypes for DRB1-QAP-DQA1-DQB1 in patients and controls. Two haplotypes DRB1*02-QAP1.2-DQA1*0102-DQB1*0602-and DRB1*03-QAP4.1-DQA1*0501-DQB1*0201 are significantly increased in patient as compared to controls (p<0.01, p corr. = n.s., RR = 1.8 and p <10–7, p corr. <10–5, RR = 3.1, respectively). The analysis of relative risks attributed to the various alleles of QAP, DQA1, and DQB1 as well as the investigation of the deduced DRB1-QAP-DQA1-DQB1 haplotypes leads to the conclusion that QAP4.1 and DQA1*0501 on the DR3 haplotypes are probably not involved in SLE susceptibility. There is no evidence for the involvement of DQ2 / dimers coded in transposition. Thus, susceptibility to SLE is on the DR3 haplotype most probably localized at DRB1 or telomeric of DRB1, while for the DR2 haplotype such orientation cannot be given.
SLE study group members: M. Baur, A. Corvetta, H. Ehrfeld, J. Frey, J. R. Kalden, F. Krapf, B. Lang, G. G. Lange, K. Pirner, C. Rittner, E. Röther, P. Schneider, H. P. Seelig, S. Seuchter, W. Stangel, C. Specker, P. Späth, H. Deicher.
Correspondence to: Z. Yao. 相似文献
69.
Heilmeyer Ludwig M. G. Gerschinski Andrea M. Meyer Helmut E. Jennissen Herbert P. 《Molecular and cellular biochemistry》1993,127(1):19-30
Holophosphorylase kinase was digested with Glu-C specific protease; from the peptide mixture calmodulin binding peptides were isolated by affinity chromatography and identified by N-terminal sequence analysis. Two peptides originating from the subunit, having a high tendency to form a positively charged amphiphilic helix and containing tryptophane, were synthesized. Additionally, a homologous region of the subunit and a peptide from the subunit present in a region deleted in the isoform were also selected for synthesis. Binding stoichiometry and affinity were determined by following the enhancement in tryptophane fluorescence occurring upon 1:1 complex formation between these peptides and calmodulin. Finally, Ca2+ binding to calmodulin in presence of peptides was measured. By this way, the peptides 542–566, 547–571, 660–677 and 597–614 have been found to bind specifically to calmodulin.Together with previously predicted and synthesized calmodulin binding peptides four calmodulin binding regions have been characterized on each the and subunits. It can be concluded that endogenous calmodulin can bind to two calmodulin binding regions in as well as to two regions in and . Exogenous calmodulin can bind to two regions in and in . A binding stoichiometry of 0.8mol of calmodulin/ protomer of phosphorylase kinase has been determined by inhibiting the ubiquitination of calmodulin with phosphorylase kinase. Phosphorylase kinase is half maximally activated by 23nM calmodulin which is in the affinity range of calmodulin binding peptides from to calmodulin. Therefore, binding of exogenous calmodulin to activates the enzyme. A model for switching endogenous calmodulin between , and and modulation of ATP binding to as well as Mg2+/ADP binding to by calmodulin is presented. 相似文献
70.
The development of the tectum mesencephali was studied in the frog Rana temporaria and the salamander Pleurodeles waltl by means of nuclear staining and by labeling of cells with bromodeoxyuridine (BrdU). The general spatial and temporal pattern of cell proliferation and cell migration is the same in both species, despite drastic differences in overall tectal morphology. However, the salamander species differs from the frog species by (1) a generally lower cell proliferation rate, (2) a reduction in the activity of the lateral proliferation zone, and (3) a reduction in the formation of superficial cellular layers. Because point (3) affects processes that occur late in ontogeny, our experiments provide evidence that the simple morphology of the tectum of Pleurodeles waltl, compared with the multilayered tectum of Rana, is a consequence of a paedomorphic alteration of the ancestral developmental pattern of the amphibian tectum. 相似文献