Chromosome segregation in female germ cells and early embryonic blastomeres is known to be highly prone to errors. The resulting aneuploidy is therefore the most frequent cause of termination of early development and embryo loss in mammals. And in specific cases, when the aneuploidy is actually compatible with embryonic and fetal development, it leads to severe developmental disorders. The main surveillance mechanism, which is essential for the fidelity of chromosome segregation, is the Spindle Assembly Checkpoint (SAC). And although all eukaryotic cells carry genes required for SAC, it is not clear whether this pathway is active in all cell types, including blastomeres of early embryos. In this review, we will summarize and discuss the recent progress in our understanding of the mechanisms controlling chromosome segregation and how they might work in embryos and mammalian embryos in particular. Our conclusion from the current literature is that the early mammalian embryos show limited capabilities to react to chromosome segregation defects, which might, at least partially, explain the widespread problem of aneuploidy during the early development in mammals.

• MeSH
• aneuploidie MeSH
• chromozomy MeSH
• embryonální vývoj * genetika   MeSH
• lidé MeSH
• savci genetika   MeSH
• segregace chromozomů * MeSH
• velikost buňky MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Background and Aims: Aesculus L. (horse chestnut, buckeye) is a genus of 12-19 extant woody species native to the temperate Northern Hemisphere. This genus is known for unusually large seeds among angiosperms. While chromosome counts are available for many Aesculus species, only one has had its genome size measured. The aim of this study is to provide more genome size data and analyse the relationship between genome size and seed mass in this genus. Methods: Chromosome numbers in root tip cuttings were confirmed for four species and reported for the first time for three additional species. Flow cytometric measurements of 2C nuclear DNA values were conducted on eight species, and mean seed mass values were estimated for the same taxa. Key Results: The same chromosome number, 2 n = 40, was determined in all investigated taxa. Original measurements of 2C values for seven Aesculus species (eight taxa), added to just one reliable datum for A. hippocastanum , confirmed the notion that the genome size in this genus with relatively large seeds is surprisingly low, ranging from 0·955 pg 2C -1 in A. parviflora to 1·275 pg 2C -1 in A. glabra var. glabra. Conclusions: The chromosome number of 2 n = 40 seems to be conclusively the universal 2 n number for non-hybrid species in this genus. Aesculus genome sizes are relatively small, not only within its own family, Sapindaceae, but also within woody angiosperms. The genome sizes seem to be distinct and non-overlapping among the four major Aesculus clades. These results provide an extra support for the most recent reconstruction of Aesculus phylogeny. The correlation between the 2C values and seed masses in examined Aesculus species is slightly negative and not significant. However, when the four major clades are treated separately, there is consistent positive association between larger genome size and larger seed mass within individual lineages.

• MeSH
• Aesculus genetika   fyziologie   MeSH
• chromozomy rostlin * MeSH
• délka genomu * MeSH
• genom rostlinný * MeSH
• ploidie MeSH
• semena rostlinná fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH

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

Delece dlouhých ramen chromozómu 5 (5q-) patří k nejčastějším strukturním aberacím u nemocných s maligním onemocněním myeloidní řady. Analýzou zlomových míst bylo prokázáno, že tato delece je intersticiální a její rozsah se u jednotlivých nemocných liší. Nejčastějším společným deletovaným segmentem je chromozomová oblast 5q31. V současné době je tato oblast intenzivně studována na molekulární úrovni se snahou lokalizovat zde jeden či více nádorových supresorových genů. Přestože nádorový supresorový gen v pruhu 5q31 nebyl dosud identifikován, intenzivní studium nových kandidátů na tyto geny pokračuje. Jejich izolace by přispěla k odhalení a pochopení molekulárních mechanizmů hematopoézy a leukemické transformace buněk.

Deletion of part of the long arm of chromosome 5 (5q-) is one of the most common structural aberrations in patients with myeloid disorders. The deletion is interstitial and the deleted segment is variable in size and breakpoint localization. Precise analysis of chromosomal breakpoints proved that band 5q31 is the most common deleted region. Extensive molecular studies have been performed to identify one or several tumor suppressor gene(s) in this critical region. Although these genes have not been identified as yet, the candidate genes are being intensively studied. Isolation and characterization of tumor suppressor genes will lead to the understanding of molecular mechanisms of normal hematopoiesis and that of leukemic transformation.

• MeSH
• chromozomální delece MeSH
• cytogenetika MeSH
• finanční podpora výzkumu jako téma MeSH
• fluorescence MeSH
• hematologické nádory genetika   MeSH
• hybridizace in situ MeSH
• lidé MeSH
• Check Tag
• lidé MeSH

The human bed bug Cimex lectularius is one of the most prevalent human ectoparasites in temperate climate zones. The cytogenetic features of this resilient pest include holokinetic chromosomes, special chromosome behavior in meiosis, and numerical variation of chromosomes, where the diploid number ranges from 26 + X1 X2 Y to 26 + X1-20 Y. It is desirable to assess the nuclear DNA content of various cytotypes for a further detailed study of the C. lectularius genome. Detailed knowledge of the DNA content of this parasite could also clarify the origin of additional chromosomes. The average nuclear genome size C. lectularius with 2n = 26 + X1 X2 Y is 2C = 1.94 pg for males and 1.95 pg for females. There is a significant correlation between genome size and the number of chromosomes, but in some specimens with additional chromosomes, nuclear genome size decreases or remains average. Several species used as the internal reference standard were tested for further investigations of genome size in C. lectularius, and the plant Solanum pseudocaspicum turned out to be the most suitable. © 2019 International Society for Advancement of Cytometry.

• MeSH
• barvení a značení MeSH
• buněčné jádro chemie   genetika   MeSH
• cytogenetika MeSH
• délka genomu * MeSH
• indoly MeSH
• meióza genetika   MeSH
• metafáze genetika   MeSH
• mitóza genetika   MeSH
• pohlavní chromozomy * MeSH
• propidium MeSH
• průtoková cytometrie MeSH
• štěnice genetika   MeSH
• zastoupení bazí MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Genome size and chromosome number of five Cimicidae species were compared with the similar data recently received from Cimex lectularius parasitizing human. The average nuclear DNA content (males) was 2C = 1.47 pg in C. hemipterus, 2C = 1.61 pg in C. hirundinis, 2C = 1.80 pg in C. lectularius from bats, 2C = 1.68 pg in C. pipistrelli, and 2C = 1.22 pg in Paracimex cf. chaeturus. In the genomes of all cimicid species analyzed, the average GC content ranged from 32.74% in C. pipistrelli to 35.87% in P. cf. chaeturus. Chromosome variability with two male cytotypes, 2n = 28 + X1 X2 Y and 28 + X1 X2 X3 Y, was confirmed in C. pipistrelli. In addition, intraspecific variability in chromosome number was revealed in C. lectularius from bats with 2n = 26 + X1 X2 Y and 26 + X1 X2 X3 Y. We suggest that the origin of intraspecific variability in chromosome number of C. lectularius from bats and C. pipistrelli is not only the result of simple fragmentation, but additive rearrangements like duplications are probably also involved. © 2019 International Society for Advancement of Cytometry.

• MeSH
• buněčné jádro genetika   metabolismus   MeSH
• Chiroptera MeSH
• chromozomy genetika   MeSH
• cytogenetické vyšetření MeSH
• délka genomu MeSH
• fragmentace DNA MeSH
• gonády cytologie   MeSH
• lidé MeSH
• ploidie MeSH
• pohlavní chromozomy genetika   MeSH
• průtoková cytometrie MeSH
• štěnice genetika   metabolismus   MeSH
• zárodečné buňky chemie   metabolismus   MeSH
• zastoupení bazí genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

• MeSH
• krysa rodu rattus MeSH
• potkani inbrední SHR genetika   MeSH
• semenné váčky anatomie a histologie   MeSH
• velikost vrhu genetika   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

The species-rich and widespread genus Taraxacum F. H. Wiggers, 1780 (Asteraceae subfamily Cichorioideae) is one of the most taxonomically complex plant genera in the world, mainly due to its combination of different sexual and asexual reproduction strategies. Polyploidy is usually confined to apomictic microspecies, varying from 3x to 6x (rarely 10x). In this study, we focused on Taraxacum sect. Taraxacum (= T.sect.Ruderalia; T.officinale group), i.e., the largest group within the genus. We counted chromosome numbers and measured the DNA content for species sampled in Central Europe, mainly in Czechia. The chromosome number of the 28 species (T.aberrans Hagendijk, Soest & Zevenbergen, 1974, T.atroviride Štěpánek & Trávníček, 2008, T.atrox Kirschner & Štěpánek, 1997, T.baeckiiforme Sahlin, 1971, T.chrysophaenum Railonsala, 1957, T.coartatum G.E. Haglund, 1942, T.corynodes G.E. Haglund, 1943, T.crassum H. Øllgaard & Trávníček, 2003, T.deltoidifrons H. Øllgaard, 2003, T.diastematicum Marklund, 1940, T.gesticulans H. Øllgaard, 1978, T.glossodon Sonck & H. Øllgaard, 1999, T.guttigestans H. Øllgaard in Kirschner & Štěpánek, 1992, T.huelphersianum G.E. Haglund, 1935, T.ingens Palmgren, 1910, T.jugiferum H. Øllgaard, 2003, T.laticordatum Marklund, 1938, T.lojoense H. Lindberg, 1944 (= T.debrayi Hagendijk, Soest & Zevenbergen, 1972, T.lippertianum Sahlin, 1979), T.lucidifrons Trávníček, ineditus, T.obtusifrons Marklund, 1938, T.ochrochlorum G.E. Haglund, 1942, T.ohlsenii G.E. Haglund, 1936, T.perdubium Trávníček, ineditus, T.praestabile Railonsala, 1962, T.sepulcrilobum Trávníček, ineditus, T.sertatum Kirschner, H. Øllgaard & Štěpánek, 1997, T.subhuelphersianum M.P. Christiansen, 1971, T.valens Marklund, 1938) is 2n = 3x = 24. The DNA content ranged from 2C = 2.60 pg (T.atrox) to 2C = 2.86 pg (T.perdubium), with an average value of 2C = 2.72 pg. Chromosome numbers are reported for the first time for 26 species (all but T.diastematicum and T.obtusifrons), and genome size estimates for 26 species are now published for the first time.

• Publikační typ
• časopisecké články MeSH

The large bread wheat genome (1C approximately 17 Gbp) contains a preponderance of repetitive DNA and the species is polyploid. These characteristics together serve to hamper the molecular analysis of the wheat genome. Its complexity can, however, be reduced by using flow cytometry to isolate individual chromosomes, and these can be exploited to construct chromosome-specific BAC libraries. Such libraries simplify the task of physical map construction, positional cloning and the targeted development of genetic markers. Rapid improvements in the efficiency and cost of DNA sequencing provide an opportunity to contemplate sequencing the wheat genome by preparing sequence-ready physical maps for each chromosome or chromosome arm in turn. The quality of the chromosome-specific libraries depends on their chromosome coverage and the mean insert size. First-generation libraries suffered from a relatively low mean insert size, but improvements to the protocol have generated a second wave of libraries with a significantly increased mean insert size and better chromosome coverage. Each chromosome (arm)-specific library is composed of a manageable number of clones, and so represents a practical tool in the area of wheat genomics.

• MeSH
• chromozomy rostlin genetika   MeSH
• DNA rostlinná genetika   MeSH
• fyzikální mapování chromozomů MeSH
• genetické markery MeSH
• genom rostlinný MeSH
• genomika MeSH
• genová knihovna MeSH
• hybridizace in situ fluorescenční MeSH
• polyploidie MeSH
• průtoková cytometrie MeSH
• pšenice genetika   MeSH
• umělé bakteriální chromozomy genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Genome analysis in many plant species is hampered by large genome size and by sequence redundancy due to the presence of repetitive DNA and polyploidy. One solution is to reduce the sample complexity by dissecting the genomes to single chromosomes. This can be realized by flow cytometric sorting, which enables purification of chromosomes in large numbers. Coupling the chromosome sorting technology with next generation sequencing provides a targeted and cost effective way to tackle complex genomes. The methods outlined in this article describe a procedure for preparation of chromosomal DNA suitable for next-generation sequencing.

• MeSH
• chromozomy rostlin ultrastruktura   MeSH
• délka genomu MeSH
• fluorescenční mikroskopie MeSH
• genom rostlinný * MeSH
• hybridizace in situ fluorescenční MeSH
• ječmen (rod) cytologie   genetika   MeSH
• klíčení genetika   MeSH
• metafáze genetika   MeSH
• polyploidie MeSH
• průtoková cytometrie metody   MeSH
• pšenice cytologie   genetika   MeSH
• sekvenční analýza DNA MeSH
• semena rostlinná genetika   MeSH
• umělé bakteriální chromozomy MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• žito cytologie   genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH