Horová, Lucie*
Dotaz
Zobrazit nápovědu
BACKGROUND AND AIMS: The genus Carex exhibits karyological peculiarities related to holocentrism, specifically extremely broad and almost continual variation in chromosome number. However, the effect of these peculiarities on the evolution of the genome (genome size, base composition) remains unknown. While in monocentrics, determining the arithmetic relationship between the chromosome numbers of related species is usually sufficient for the detection of particular modes of karyotype evolution (i.e. polyploidy and dysploidy), in holocentrics where chromosomal fission and fusion occur such detection requires knowledge of the DNA content. METHODS: The genome size and GC content were estimated in 157 taxa using flow cytometry. The exact chromosome numbers were known for 96 measured samples and were taken from the available literature for other taxa. All relationships were tested in a phylogenetic framework using the ITS tree of 105 species. KEY RESULTS: The 1C genome size varied between 0·24 and 1·64 pg in Carex secalina and C. cuspidata, respectively. The genomic GC content varied from 34·8 % to 40·6 % from C. secalina to C. firma. Both genomic parameters were positively correlated. Seven polyploid and two potentially polyploid taxa were detected in the core Carex clade. A strong negative correlation between genome size and chromosome number was documented in non-polyploid taxa. Non-polyploid taxa of the core Carex clade exhibited a higher rate of genome-size evolution compared with the Vignea clade. Three dioecious taxa exhibited larger genomes, larger chromosomes, and a higher GC content than their hermaphrodite relatives. CONCLUSIONS: Genomes of Carex are relatively small and very GC-poor compared with other angiosperms. We conclude that the evolution of genome and karyotype in Carex is promoted by frequent chromosomal fissions/fusions, rare polyploidy and common repetitive DNA proliferation/removal.
- MeSH
- Carex (rostlina) genetika MeSH
- chromozomy rostlin genetika MeSH
- délka genomu genetika MeSH
- fylogeneze MeSH
- genom rostlinný genetika MeSH
- Markovovy řetězce MeSH
- metoda Monte Carlo MeSH
- molekulární evoluce * MeSH
- polyploidie MeSH
- zastoupení bazí genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
• Knowledge of the phylogenetic pattern and biological relevance of the base composition of large eukaryotic genomes (including those of plants) is poor. With the use of flow cytometry (FCM), the amount of available data on the guanine + cytosine (GC) content of plants has nearly doubled in the last decade. However, skepticism exists concerning the reliability of the method because of uncertainty in some input parameters. • Here, we tested the reliability of FCM for estimating GC content by comparison with the biochemical method of DNA temperature melting analysis (TMA). We conducted measurements in 14 plant species with a maximum currently known GC content range (33.6-47.5% as measured by FCM). We also compared the estimations of the GC content by FCM with genomic sequences in 11 Oryza species. • FCM and TMA data exhibited a high degree of correspondence which remained stable over the relatively wide range of binding lengths (3.39-4.09) assumed for the base-specific dye used. A high correlation was also observed between FCM results and the sequence data in Oryza, although the latter GC contents were consistently lower. • Reliable estimates of the genomic base composition in plants by FCM are comparable with estimates obtained using other methods, and so wider application of FCM in future plant genomic research, although it would pose a challenge, would be supported by these findings.
- MeSH
- Bacteria genetika MeSH
- denaturace nukleových kyselin MeSH
- DNA rostlinná genetika MeSH
- druhová specificita MeSH
- genom rostlinný genetika MeSH
- průtoková cytometrie metody MeSH
- reprodukovatelnost výsledků MeSH
- sekvence nukleotidů MeSH
- teplota MeSH
- zastoupení bazí genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Two chromosomal structures, known as monocentric and holocentric chromosomes, have evolved in eukaryotes. Acentric fragments of monocentric chromosomes are unequally distributed to daughter cells and/or lost, while holocentric fragments are inherited normally. In monocentric species, unequal distribution should generate chimeras of cells with different nuclear DNA content. We investigated whether such differences in monocentric species are detectable by flow cytometry (FCM) as (i) a decreased nuclear DNA content and (ii) an increased coefficient of variance (CV) of the G1 peak after gamma radiation-induced fragmentation. We compared 13 monocentric and 9 holocentric plant species. Unexpectedly, monocentrics and holocentrics did not differ with respect to parameters (i) and (ii) in their response to gamma irradiation. However, we found that the proportion of G2 nuclei was highly elevated in monocentrics after irradiation, while holocentrics were negligibly affected. Therefore, we hypothesize that DNA-damaging agents induce cell cycle arrest leading to endopolyploidy only in monocentric and not (or to much lesser extent) in holocentric plants. While current microscope-dependent methods for holocentrism detection are unreliable for small and numerous chromosomes, which are common in holocentrics, FCM can use somatic nuclei. Thus, FCM may be a rapid and reliable method of high-throughput screening for holocentric candidates across plant phylogeny.
BACKGROUND AND AIMS: Studies in the carnivorous family Lentibulariaceae in the last years resulted in the discovery of the smallest plant genomes and an unusual pattern of genomic GC content evolution. However, scarcity of genomic data in other carnivorous clades still prevents a generalization of the observed patterns. Here the aim was to fill this gap by mapping genome evolution in the second largest carnivorous family, Droseraceae, where this evolution may be affected by chromosomal holokinetism in Drosera METHODS: The genome size and genomic GC content of 71 Droseraceae species were measured by flow cytometry. A dated phylogeny was constructed, and the evolution of both genomic parameters and their relationship to species climatic niches were tested using phylogeny-based statistics. KEY RESULTS: The 2C genome size of Droseraceae varied between 488 and 10 927 Mbp, and the GC content ranged between 37·1 and 44·7 %. The genome sizes and genomic GC content of carnivorous and holocentric species did not differ from those of their non-carnivorous and monocentric relatives. The genomic GC content positively correlated with genome size and annual temperature fluctuations. The genome size and chromosome numbers were inversely correlated in the Australian clade of Drosera CONCLUSIONS: Our results indicate that neither carnivory (nutrient scarcity) nor the holokinetism have a prominent effect on size and DNA base composition of Droseraceae genomes. However, the holokinetic drive seems to affect karyotype evolution in one of the major clades of Drosera Our survey confirmed that the evolution of GC content is tightly connected with the evolution of genome size and also with environmental conditions.
BACKGROUND AND AIMS: Ultraviolet-B radiation (UV-B) radiation damages the DNA, cells and photosynthetic apparatus of plants. Plants commonly prevent this damage by synthetizing UV-B-protective compounds. Recent laboratory experiments in Arabidopsis and cucumber have indicated that plants can also respond to UV-B stress with endopolyploidy. Here we test the generality of this response in natural plant populations, considering their monocentric or holocentric chromosomal structure. METHODS: We measured the endopolyploidy index (flow cytometry) and the concentration of UV-B-protective compounds in leaves of 12 herbaceous species (1007 individuals) from forest interiors and neighbouring clearings where they were exposed to increased UV-B radiation (103 forest + clearing populations). We then analysed the data using phylogenetic mixed models. KEY RESULTS: The concentration of UV-B protectives increased with UV-B doses estimated from hemispheric photographs of the sky above sample collection sites, but the increase was more rapid in species with monocentric chromosomes. Endopolyploidy index increased with UV-B doses and with concentrations of UV-B-absorbing compounds only in species with monocentric chromosomes, while holocentric species responded negligibly. CONCLUSIONS: Endopolyploidy seems to be a common response to increased UV-B in monocentric plants. Low sensitivity to UV-B in holocentric species might relate to their success in high-UV-stressed habitats and corroborates the hypothesized role of holocentric chromosomes in plant terrestrialization.
- MeSH
- Arabidopsis * MeSH
- chromozomy * MeSH
- fylogeneze MeSH
- lidé MeSH
- listy rostlin MeSH
- ultrafialové záření MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Závěrečná zpráva o řešení grantu Interní grantové agentury MZ ČR
Přeruš. str. : il., tab. ; 30 cm
Srovnání výsledků CT a PET vyšetření se zaměřením na oblast svodných lymfatických uzlin. Určení cílového objemu radioterapie podle výsledků PET a CT vyšetření. Srovnání výsledků PET vyšetření u pacientek s karcinomem děložního čípku před zahájením radioterapie (chemoradioterapie) a 6-8 týdnů po jejím ukončení. Stanovení prediktivní hodnoty PET v léčebné strategii karcinomu čípku.; Comparasion of the results of staging of lymph nodes between CT scan and PET. Dation of the target volume with respect PET and CT. Comparasion PET scan before and after radiotherapy (chemoradiotherapy) in patients with cervix carcinoma. Defination of thepredict value of PET in the therapeutic strategy of cervix carcinoma.
- MeSH
- angioimunoblastická lymfadenopatie MeSH
- nádory děložního čípku diagnóza radioterapie MeSH
- pozitronová emisní tomografie MeSH
- prognóza MeSH
- výsledek terapie MeSH
- Konspekt
- Gynekologie. Porodnictví
- NLK Obory
- onkologie
- gynekologie a porodnictví
- NLK Publikační typ
- závěrečné zprávy o řešení grantu IGA MZ ČR
Polyploidy and increased genome size are hypothesized to increase organismal nutrient demands, namely of phosphorus (P), which is an essential and abundant component of nucleic acids. Therefore, polyploids and plants with larger genomes are expected to be selectively disadvantaged in P-limited environments. However, this hypothesis has yet to be experimentally tested. We measured the somatic DNA content and ploidy level in 74 vascular plant species in a long-term fertilization experiment. The differences between the fertilizer treatments regarding the DNA content and ploidy level of the established species were tested using phylogeny-based statistics. The percentage and biomass of polyploid species clearly increased with soil P in particular fertilizer treatments, and a similar but weaker trend was observed for the DNA content. These increases were associated with the dominance of competitive life strategy (particularly advantageous in the P-treated plots) in polyploids and the enhanced competitive ability of dominant polyploid grasses at high soil P concentrations, indicating their increased P limitation. Our results verify the hypothesized effect of P availability on the selection of polyploids and plants with increased genome sizes, although the relative contribution of increased P demands vs increased competitiveness as causes of the observed pattern requires further evaluation.
- MeSH
- délka genomu * MeSH
- DNA rostlinná MeSH
- fosfor metabolismus MeSH
- genom rostlinný * MeSH
- lipnicovité genetika MeSH
- molekulární evoluce * MeSH
- polyploidie * MeSH
- průmyslová hnojiva * MeSH
- půda chemie MeSH
- rostliny genetika MeSH
- selekce (genetika) MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
