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M J Olszewska H Kuran B Damsz K Marciniak 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1987,25(1):69-77
Experimental model consisted in blocking cells in G1 phase by cold treatment (12 h, 10 degrees C); following 3 h of postincubation at 20 degrees C, cells initiated S phase. In the present studies it has been shown that 2 h postincubation at 20 degrees C of cold-treated young seedlings of Helianthus annuus L. results in transformation of inactive meristematic nucleoli, characterized by small sizes, reduced amount of dry mass and granular component and by the presence of few and large fibrillar centres into large active nucleoli displaying high dry mass and granular component contents, numerous and small fibrillar centres. After 3 h of postincubation at 20 degrees C, nucleoli lose their granular component, decrease in size and dry mass content. At this moment cytoplasm enriches in ribosomes and its dry mass increases. Maximum of nucleolar activity is preceded by an accumulation of proteins in nucleoli. It is concluded that an enhanced transport of ribosomes is one of the conditions of S phase initiation. 相似文献
3.
K Marciniak A Bilecka 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1985,23(4):231-245
Using cytophotometric method, after staining preparations with gallocyanin RNA content was examined in nucleus, nucleolus and cytoplasm of six species of angiospermal plants in successive (1-7 mm) segments of root representing successive zones of differentiation. During the cell cycle, RNA content duplicates in the nucleus, nucleolus and cytoplasm of meristematic cells. On the other hand, during growth and differentiation of parenchyma cells in species with endoreplication the content of nucleolar RNA does not increase in proportion with DNA content. High level of endoreplication is connected with high nucleolar RNA content and low cytoplasmic RNA content. In species without endoreplication at low nucleolar RNA content, a considerable growth of cytoplasmic RNA content takes place. 相似文献
4.
The effects of mispair and nonpair correction in hybrid DNA on base ratios (G + C content) and total amounts of DNA 总被引:1,自引:0,他引:1
Base ratios and total DNA amounts can vary substantially between and within
higher taxa and genera, and even within species. Gene conversion is one of
several mechanisms that could cause such changes. For base substitutions,
disparity in conversion direction is accompanied by an equivalent disparity
in base ratio at the heterozygous site. Disparity in the direction of gene
conversion at meiosis is common and can be extreme. For transitions (which
give purine [R]/pyrimidine [Y] mispairs) and for transversions giving
unlike R/R and Y/Y mispairs in hybrid DNA, this disparity could give slow
but systematic changes in G + C percentage. For transversions giving like
R/R and Y/Y mispairs, it could change AT/TA and CG/GC ratios. From the
extent of correction direction disparity, one can deduce properties of
repair enzymes, such as the ability (1) to excise preferentially the purine
from one mispair and the pyrimidine from the other for two different R/Y
mispairs from a single heterozygous site and (2) to excise one base
preferentially from unlike R/R or Y/Y mispairs. Frame-shifts usually show
strong disparity in conversion direction, with preferential cutting of the
nonlooped or the looped-out strand of the nonpair in heterozygous h-DNA.
The opposite directions of disparity for frame-shifts and their intragenic
suppressors as Ascobolus suggest that repair enzymes have a strong,
systematic bias as to which strand is cut. The conversion spectra of
mutations induced with different mutagens suggest that the nonlooped strand
is preferentially cut, so that base additions generally convert to mutant
and deletions generally convert to wild-type forms. Especially in
nonfunctional or noncoding DNA, this could cause a general increase in DNA
amounts. Conversion disparity, selection, mutation, and other processes
interact, affecting rates of change in base ratios and total DNA.
相似文献
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M J Olszewska A Bilecka H Kuran K Marciniak R Osiecka 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1989,27(2):107-112
In root meristems of 3 species (Secale cereale L., Vicia faba L. subsp. minor, Allium cepa L.) the durations of cell cycles and their phases were calculated using 3H-thymidine labelling. In the above species and in Helianthus annuus L. (parameters of the cell cycle determined earlier) the G1 and G2 phase durations were different: G1 + 1/2 M from 3 h to 6.1 h, G2 + 1/2 M from 1.1. h to 8.3 h, depending on the species. The rate of rRNA transport from nucleoli into cytoplasm during recovery after cold treatment was calculated from our data presented earlier. The results indicate that in 4 species studied there is no correlation (at P = 0.05) between the rate of rRNA transport and the duration of G1 and G2 phases. 相似文献
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9.
Sally E. Thomas Elke Malzer Adriana Ordó?ez Lucy E. Dalton Emily F. A. van ′t Wout Elizabeth Liniker Damian C. Crowther David A. Lomas Stefan J. Marciniak 《The Journal of biological chemistry》2013,288(11):7606-7617
Cell cycle checkpoints ensure that proliferation occurs only under permissive conditions, but their role in linking nutrient availability to cell division is incompletely understood. Protein folding within the endoplasmic reticulum (ER) is exquisitely sensitive to energy supply and amino acid sources because deficiencies impair luminal protein folding and consequently trigger ER stress signaling. Following ER stress, many cell types arrest within the G1 phase, although recent studies have identified a novel ER stress G2 checkpoint. Here, we report that ER stress affects cell cycle progression via two classes of signal: an early inhibition of protein synthesis leading to G2 delay involving CHK1 and a later induction of G1 arrest associated both with the induction of p53 target genes and loss of cyclin D1. We show that substitution of p53/47 for p53 impairs the ER stress G1 checkpoint, attenuates the recovery of protein translation, and impairs induction of NOXA, a mediator of cell death. We propose that cell cycle regulation in response to ER stress comprises redundant pathways invoked sequentially first to impair G2 progression prior to ultimate G1 arrest. 相似文献
10.
Natalia Marciniak Maciej Skoracki Martin Hromada 《New Zealand journal of zoology.》2019,46(4):348-352
A new species of quill mite of the family Syringophilidae (Acariformes: Prostigmata), Peristerophila nestoriae sp. nov. from New Zealand Kaka, Nestor meridionalis (Gmelin) (Psittaciformes: Strigopidae) is described. This new species is morphologically similar to Peristerophila falcophila [Skoracki M, Hromada M, Kaszewska K, Unsoeld M. 2018. Peristerophila falcophila sp. nov., a new species and first record of quill mites (Acariformes: Syringophilidae) parasitizing birds of the order Falconiformes. Acta Parasitologica. 63:744–749. https://doi.org/10.1515/ap-2018-0088], and differs from it as follow: the stylophore is 130–140 long (vs. 150–160 long); the propodonotal shield bear bases of setae ve, si, and c1 (vs. only ve and si on the propodonotal shield); fan-like setae p′ and p″ of legs III and IV with 11–13 tines (vs. 10 tines); the lengths of setae ag2 40–50 (vs. 55–70). Our finding is the first record of the presence of syringophilid mite on host of the family Strigopidae and first report of the member of Peristerophila on psittaciform birds. So far, the syringophilids mites have not been found in New Zealand.
LSID: urn:lsid:zoobank.org:pub:FB0C5B37-DF42-428C-8C81-8FA56EA67504 相似文献