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91.
Different sublines of Jurkat cells respond with varying susceptibility of internucleosomal DNA degradation to different mediators of apoptosis 总被引:2,自引:0,他引:2
The ability of two different Jurkat sublines, termed standard and JM, to form DNA ladders was investigated after various apoptotic stimuli. Exposure to a broad spectrum of drugs interfering with signal transduction or cellular metabolism revealed distinct differences between both Jurkat sublines with regard to the pattern of DNA degradation. In standard Jurkat cells, internucleosomal DNA cleavage occurred only after treatment with the protein kinase inhibitor staurosporine. In contrast, the JM subline responded with internucleosomal DNA fragmentation to exposure to gemcitabine, cycloheximide or staurosporine. All drugs induced the formation of DNA fragments of about 50 kb in both sublines, as revealed by pulse field electrophoresis, except H2O2, which caused unspecific DNA degradation. The staurosporine-induced DNA ladder formation was accompanied by an increase in caspase-3 activity in both lines which, however, was considerably lower in Jurkat JM cells after gemcitabine or cycloheximide exposure. When the analysis of internucleosomal DNA degradation was carried out after mycoplasma infection, both Jurkat lines responded with DNA ladder formation after exposure to all drugs used (here only shown for the standard subline). Employing the zymogram technique, nuclease activities of 47 kDa and 54 kDa were detected in culture supernatants, cell homogenates and nuclear extracts only when mycoplasma-infected, whereas the samples obtained from mycoplasma-free sublines were nuclease-negative using this technique, indicating that these endonucleases were of mycoplasmal origin. After drug exposure, the mycoplasmal nucleases must have gained access to the cytoplasm and nuclei of their host cells by an unknown mechanism. 相似文献
92.
A β-glucosidase that cleaves the biologically inactive hormone conjugates cytokinin-O- and kinetin-N3-glucosides is encoded
by the maize Zm-p60.1 gene. The expression of the Zm-p60.1 gene was analyzed by Northern blot analysis and in-situ hybridization. It was found that the expression levels of the Zm-p60.1-specific mRNA changed after pollination of carpellate inflorescences. The Zm-p60.1 cDNA was expressed in E. coli and antibodies were raised against this protein. An antibody was used to determine the tissue-specific localization of this
protein. By in situ immunolocalization experiments, this protein was found to be located in cell layers below the epidermis
and around the vascular bundles of the coleoptile. In the primary leaf, the Zm-p60.1 protein was detected in cells of the
outermost cell layer and around the vascular tissue. In floral tissue, Zm-p60.1 was present in the glumes, the carpels and
in the outer cell layer of the style. In coleoptiles, as determined by immuno-electronmicroscopy, the Zm-p60.1 protein was
located exclusively in the plastids.
Received: 11 August 1998 / Accepted: 30 December 1998 相似文献
93.
Chromosomes of the pea (Pisum sativum L.) were submitted to fluorescent in situ hybridization (FISH) with probes specific for the oligonucleotides (AG)12, (AC)12, (GAA)10, and (GATA)7 and for the genes encoding 25S rRNA, 5S rRNA and the storage proteins legumin A, K and vicilin. A fourth 5S rRNA gene locus,
apparently specific for an accession of the cultivar Grüne Victoria, was newly detected. This allowed all seven chromosome
pairs to be distinguished by FISH signals of rRNA genes. The same was possible using a combination of oligonucleotide probes
or of oligonucleotides and rRNA gene-specific probes in multicolour FISH. Rehybridization with the 5S rRNA gene-specific probe
allowed us to assign vicilin genes to the short arm of chromosome 5, the single legumin A locus to the long arm of chromosome
3 and the legumin B-type genes (exemplified by legumin K) to one locus on the short arm of chromosome 6. Correlation of these
data with an updated version of the pea genetic map allowed the assignment of most linkage groups to defined chromosomes.
It only remains to be established which of linkage groups IV and VII corresponds to the satellited chromosomes 4 or 7, respectively.
Received: 13 February 1998; in revised form: 3 April 1998 / Accepted: 7 April 1998 相似文献
94.
95.
Gerda Oswald Ingo Rombeck B. Song H. Sigel B. Lippert 《Journal of biological inorganic chemistry》1998,3(3):236-245
The synthesis of cis-Pt(NH3)2(dCMP) is reported and by various physico-chemical methods it is demonstrated that it is a macrochelate in which Pt(II) is
bound simultaneously to the N3 site of cytosine in dCMP2– and to a phosphate-oxygen atom. According to the NOESY spectra (cross-peaks between cytosine H6 and H2′ and H3′) the cytosine
ring adopts an anti orientation. Highly unusual is the significant (1 ppm) downfield shift of the sugar proton H5″ in the 1H-NMR spectrum and the sensitivity of the cytosine H6 resonance on the protonation state of the phosphate group. Based on
these three features a geometry for the macrochelate is proposed. The compound is a major product of the reaction of cis-[Pt(NH3)2(H2O)2]2+ with dCMP2– at neutral pH, but it even forms at pH 5. By applying pD-dependent NMR spectroscopy (1H, 31P) and potentiometric pH titration, it is demonstrated that the Pt-coordinated phosphate group can be protonated (pK
a/1=3.21±0.10 and 3.31±0.05, respectively), and 1H- and 31P-NMR spectra also indicate deprotonation (pK
a/2=13.35±0.25) of the exocyclic amino group of the cytosine moiety. The metal ion binding affinity of cis-Pt(NH3)2(dCMP) is very small, as shown for Cu2+ (log K<0.6). The cis-Pt(NH3)2(dCMP) complex reacts with nucleosides and nucleotides (L′) by losing its chelate structure and forming mixed ligand complexes,
cis-Pt(NH3)2(dCMP)(L′); this means that the phosphate group is released from the coordination sphere of Pt(II), indicating that the Pt(II)-O(phosphate)
bond is not very strong.
Received: 23 October 1997 / Accepted: 17 February 1998 相似文献
96.
Ingo Ott Konrad Kowalski Ronald Gust Jörg Maurer Philipp Mücke Rainer F. Winter 《Bioorganic & medicinal chemistry letters》2010,20(3):866-869
Two ethylene linked binuclear mixed ferrocene/ruthenium complexes were biologically investigated in comparison to structurally related mononuclear ferrocene or ruthenium species with styryl substituents or ligands. Results indicated that the electron distribution (but not the redox potential), cellular uptake and (to some minor extent) anti-estrogenic effects were the key contributors to antiproliferative effects observed in tumor cell lines. 相似文献
97.
98.
Roland Frey Alban Gebler Kirk A. Olson Daria Odonkhuu Guido Fritsch Nyamsuren Batsaikhan Ingo W. Stuermer 《Journal of morphology》2008,269(10):1223-1237
This study provides the first evidence of pronounced temporary laryngeal descent in a bovid species. An elaborate acoustic display is prominent in male courtship behavior of polygynous Mongolian gazelle. During rut, rounding up of females is accompanied by continuous head‐up barking by dominant males. Throughout the rut their evolutionarily enlarged larynx descends to a low mid‐neck resting position. In the course of each bark the larynx is additionally retracted toward the sternum by 30% of the resting vocal tract length. A geometric model of active larynx movements was constructed by combining results of video documentation, dissection, skeletonization, and behavioral observation. The considerable distance between resting position and maximal laryngeal descent suggests a backward tilting of the hyoid apparatus and an extension of the thyrohyoid connection during the retraction phase. Return to the resting position is effected by strap muscles and by the elastic recoil of the pharynx and the thyrohyoid connection. An intrapharyngeal inflation of the peculiar palatinal pharyngeal pouch of adult males is inferred from a short‐time expansion of the ventral neck region rostral to the laryngeal prominence. The neck of adult dominant males is accentuated by long gray guard hairs during the rut. The passive swinging of the heavy larynx of adult males during locomotion gives the impression of a handicap imposed on rutting males. Apparently, this disadvantage becomes outweighed by the profits for reproductive success. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc. 相似文献
99.
Ceftaroline is a new cephalosporin active against Methicillin-resistant Staphylococcus aureus (MRSA). Based on a representative collection of clinical S. aureus isolates from Germany, supplemented with isolates of clonal lineages ST228 and ST239, we demonstrate the in-vitro susceptibility towards ceftaroline prior to its introduction into clinical use for a total of 219 isolates. Susceptibility testing was performed by broth microdilution, disc diffusion and Etest, respectively. Results were interpreted according to EUCAST guidelines and showed considerable variance in dependence on clonal affiliation of the isolates tested. Among isolates of widespread hospital-associated lineages we found a high proportion of clinical isolates with MICs close to the EUCAST breakpoint (MIC50/90 1.0/1.5 mg/L); currently, interpretation of these “borderline” MICs is complicated by a lack of concordant susceptibility testing methods and reasonable breakpoint determination. Isolates of clonal lineages ST228 and ST239 demonstrated increased MIC50/90 values of 2.5/3.33 mg/L. Sequencing of mecA revealed no association of resistance to a specific mecA polymorphism, but rather reveals two regions in the non-penicillin-binding domain of PbP2a which displayed different combinations of mutations putatively involved in resistance development. This study provides national baseline data to (i) adjust susceptibility testing methods and current breakpoints to clinical and epidemiological requirements, (ii) evaluate current breakpoints with respect to therapeutic outcome and (iii) monitor further resistance evolution. 相似文献
100.
LUMOS - A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range
Philipp Lehner Christoph Larndorfer Emilio Garcia-Robledo Morten Larsen Sergey M. Borisov Niels-Peter Revsbech Ronnie N. Glud Donald E. Canfield Ingo Klimant 《PloS one》2015,10(6)
Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized “sensing chemistry” that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented. 相似文献