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81.
The ultrastructure of dikaryotic haustoria of sevenPucciniastrum species,Thekopsora galii, Naohidemyces vaccinii, andCalyptospora goeppertiana was investigated.Pucciniastrum actinidiae, P. agrimoniae, P. pyrolae, andCalyptospora goeppertiana revealed haustoria whose necks were wrapped by a fold of the extrahaustorial matrix. The matrix-fold ofCalyptospora goeppertiana was characteristically shaped.Pucciniastrum circaeae, P. epilobii, P. hikosanense, P. styracinum, Thekopsora galii, andNaohidemyces vaccinii showed typical haustorial necks which were not sheathed by a matrix-fold. Haustorial necks which were wrapped by a fold of the extrahaustorial matrix were designated velopedunculate, and those which were naked gymnopedunculate. The application of haustorial ultrastructure as a character for use in systematics is discussed.Part 112 of the series Studies in Heterobasidiomycetes. 相似文献
82.
Margarete Traiser Bernd Diener Dietmar Utesch Franz Oesch 《In vitro cellular & developmental biology. Animal》1995,31(4):266-273
Summary In primary monocultures of adult rat liver parenchymal cells (PC), the activities of the xenobiotic metabolizing enzymes microsomal
epoxide hydrolase (mEHb), soluble epoxide hydrolase (sEH), glutathione S-transferases (GST), and phenolsulfotransferase (ST) were reduced after 7
d to values below 33% of the initial activities. Furthermore, the gap junctional intercellular communication (GJIC), measured
after microinjection by dye transfer, decreased from 90% on Day 1 to undetectable values after 5 d in monoculture. Co-culture
of PC with nonparenchymal rat liver epithelial cells (NEC) increased (98% on Day 1) and stabilized (82% on Day 7) the homotypic
GJIC of PC. Additionally, most of the measured xenobiotic metabolizing enzyme activities were well stabilized over 1 wk in
co-culture. Because GJIC is one of several mechanisms playing an important role in cell differentiation, the importance of
GJIC for the stabilization of xenobiotic metabolizing enzymes in PC was investigated. PC in monoculture were, therefore, treated
with 2% dimethyl sulfoxide (DMSO), a differentiation promoting factor, and 1,1,1-trichloro-2,2,-bis (p-chlorophenyl) ethane
(DDT) (10 μg/ml), a liver tumor promotor and inhibitor of GJIC, was given to co-cultures of PC with NEC. DMSO significantly
stabilized (68% on Day 7), while DDT significantly inhibited (8% on Day 7) homotypic GJIC of PC in the respective culture
systems. In contrast, the activities of mEHb, sEH, GST, and ST were not affected in the presence of DMSO or DDT. These results lead to the assumption that the differentiation
parameters measured in this study (i.e., homotypic GJIC and the activities of xenobiotic metabolizing enzymes) are independently
regulated in adult rat liver PC. 相似文献
83.
A cytogenetic map of chromosome 5 from the Mediterranean fruit fly, Ceratitis capitata, was constructed. Six mutations were located by translocation, transposition or deletion mapping. This knowledge allowed alignment and orientation of the existing linkage map with the polytene chromosomes. In addition, mapping of mutations used as selectable markers in genetic sex-separation strains is an essential prerequisite for the improvement of genetic stability during mass-rearing. 相似文献
84.
Maria Rova Lars-Gunnar Franzén Per-Olof Fredriksson Stenbjörn Styring 《Photosynthesis research》1994,39(1):75-83
The psbP gene product, the so called 23 kDa extrinsic protein, is involved in water oxidation carried out by Photosystem II. However, the protein is not absolutely required for water oxidation. Here we have studied Photosystem II mediated electron transfer in a mutant of Chlamydomonas reinhardtii, the FUD 39 mutant, that lacks the psbP protein. When grown in dim light the Photosystem II content in thylakoid membranes of FUD 39 is approximately similar to that in the wild-type. The oxygen evolution is dependent on the presence of chloride as a cofactor, which activates the water oxidation with a dissociation constant of about 4 mM. In the mutant, the oxygen evolution is very sensitive to photoinhibition when assayed at low chloride concentrations while chloride protects against photoinhibition with a dissociation constant of about 5 mM. The photoinhibition is irreversible as oxygen evolution cannot be restored by the addition of chloride to inhibited samples. In addition the inhibition seems to be targeted primarily to the Mn-cluster in Photosystem II as the electron transfer through the remaining part of Photosystem II is photoinhibited with slower kinetics. Thus, this mutant provides an experimental system in which effects of photoinhibition induced by lesions at the donor side of Photosystem II can be studied in vivo.Abbreviations Chl
chlorophyll
- DCIP
2,6-dichlorophenolindophenol
- DPC
2,2-diphenylcarbonic dihydrazide
- HEPES
4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid
- P680
the primary electron donor to PS II
- PpBQ
phenyl-p-benzoquinone
- PS II
Photosystem II
- QA
the first quinone acceptor of PS II
- QB
the second quinone acceptor of PS II
- SDS
sodium dodecyl sulfate
- Tris
tris(hydroxymethyl)aminomethane
- TyrD
accessory electron donor on the D2-protein
- TyrZ
tyrosine residue, acting as electron carrier between P680 and the water oxidizing system 相似文献
85.
86.
Liang Ru Shi Dirk Eichelbauer Franz Borchard Herbert Jürgens Ulrich Göbel E. Marion Schneider 《Cancer immunology, immunotherapy : CII》1994,38(3):208-213
A selection of 16 monoclonal antibodies has been produced against a fresh Ewing's sarcoma (ES) tumor mixed with a permanent ES cell line. The majority of antibodies identify an 80-kDa molecule, which is not detected on healthy tissues except on certain cultured monocytes. One antibody recognize the CD2 ligand MIC2 and 2 antibodies (numbers 13 and 16) define a higher-molecular-mass antigen. Antibody 16 is also expressed on mesenchymal fibroblasts of bone marrow or fetal origin. Tumorspecific antigen expression is potentially linked to the chromosome 22 abnormality decribed in Ewing's sarcoma. 相似文献
87.
Nathalie Knittel Véronique Gruber Günther Hahne Philippe Lénée 《Plant cell reports》1994,14(2-3):81-86
Summary A reliable protocol for the transformation of cultivated sunflower (Helianthus annuus L.) has been established, based on microprojectile bombardment of half shoot apices in combination with Agrobacterium tumefaciens coculture. Transgenic shoots have been obtained from 5 inbred lines, although transformation efficiencies varied with the genotype. Plants expressing the transgenes could be recovered from up to 7% of the explants. A minority of plants was shown to be chimaeric for expression of ß-glucuronidase activity while most appeared to be uniformly transformed. Genetic segregation was 31 for both ß-glucuronidase and neomycine phospho transferase in some plants, indicating that the respective mother plants were uniformly transformed. Integration of the foreign genes was also shown by Southern analysis.Abbreviations BAP
benzyl amino purine
- EDTA
ethylene diamine tetraacetic acid
- GUS
ß-glucuronidase
- npt II
neomycine phospho-transferase II 相似文献
88.
In the existing genetic sexing strains for the medfly, Ceratitis capitata, male recombination leads to breakdown of the sexing mechanism under mass rearing conditions. The rate of breakdown depends on the recombination frequency and on the fitness of the recombinants. We have tested two different sexing genes, white pupa and a temperature sensitive lethal, in combination with the translocation T(Y;5)30C. Both sexing strains broke down, although at very different rates. In the case of the white pupa strain, 3.5% recombinants were observed after rearing the strain for 15 generations. The second strain, utilizing white pupa and the temperature sensitive lethal as selectable markers, already reached a comparable level after six generations and was broken down completely in the ninth generation. In these strains the frequency of recombination is high because the breakpoint of T(Y;5)30C and the sexing gene(s) are far apart. To remedy the situation, we have isolated four new translocations with breakpoints located closer to the sexing genes. Mass rearing was simulated for several generations with strains based on these translocations and no breakdown was observed under the conditions used. 相似文献
89.
Summary The chloroplast ribosomal intron of Chlamydomonas reinhardtii encodes a sequence-specific DNA endonuclease (I-CreI), which is most probably involved in the mobility of this intron. Here we show that I-CreI generates a 4 by staggered cleavage just downstream of the intron insertion site. The I-CreI recognition sequence is 19–24 by in size and is located asymmetrically around the intron insertion site. Screening of natural variants of the I-CreI recognition sequence indicates that the I-CreI endonuclease tolerates single and even multiple base changes within its recognition sequence. 相似文献
90.
Alwin Krmer Jan Pudil Heinz Frank Franz Oesch Handruedi Glatt 《Mutation research》1993,290(2):165-174
Trans-stilbene oxide, trans-β-methylstyrene, 7,8-oxide, trans-β-ethylstyrene, 7,8-oxide, trans-β-propylstyrene 7,8-oxide and 4-fluorochalcone oxide were investigated for genotoxic activity in bacterial and mammalian cells, in the absence of external xenobiotic-metabolising systems. All compounds strongly enhanced the frequency of sister-chromatid exchanges (SCE) in cultured human lymphocytes. None of them was mutagenic in Salmonella typhimurium (reversion of the his− strains TA98, TA100 and TA104). The limit of detection was 1/20,000 to 1/106 of the activity of the positive control, benzo[a]pyrene 4,5-oxide, depending on the compound and the bacterial strain. Trans-β-methylstyrene 7,8-oxide and 4-fluorochalcone oxide were additionally tested for induction of SCE and gene mutations in the same target cells, namely Chinese hamster V79 cells. Their influence on the level of SCE was similar to that observed in human lymphocytes, whilst gene mutations (at the hprt locus) were not induced. The four investigated styrene oxide derivatives are known to be excellent substrates for a mammalian enzyme, cytosolic epoxide hydrolase (cEH). 4-Fluorochalcone oxide is a potent selective inhibitor of this enzyme and is structurally similar to the investigated styrene oxide derivatives. These properties of the test compounds however cannot explain the observed discrepancies in the results, since the genetic end point (SCE versus gene mutations) was decisive, and SCE were induced in cEH-proficient human lymphocytes as well as in cEH-deficient V79 cells. 相似文献