The genomes of many plants, animals, and fungi frequently comprise dispensable B chromosomes that rely upon various chromosomal drive mechanisms to counteract the tendency of non-essential genetic elements to be purged over time. The B chromosome of rye - a model system for nearly a century - undergoes targeted nondisjunction during first pollen mitosis, favouring segregation into the generative nucleus, thus increasing their numbers over generations. However, the genetic mechanisms underlying this process are poorly understood. Here, using a newly-assembled, ~430 Mb-long rye B chromosome pseudomolecule, we identify five candidate genes whose role as trans-acting moderators of the chromosomal drive is supported by karyotyping, chromosome drive analysis and comparative RNA-seq. Among them, we identify DCR28, coding a microtubule-associated protein related to cell division, and detect this gene also in the B chromosome of Aegilops speltoides. The DCR28 gene family is neo-functionalised and serially-duplicated with 15 B chromosome-located copies that are uniquely highly expressed in the first pollen mitosis of rye.
- MeSH
- Aegilops genetika metabolismus MeSH
- chromozomy rostlin * genetika MeSH
- karyotypizace MeSH
- mitóza * genetika MeSH
- nondisjunkce genetická MeSH
- pyl genetika MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- žito * genetika MeSH
- Publikační typ
- časopisecké články MeSH
Chromosomal rearrangements are often associated with playing a role in the speciation process. However, the underlying mechanism that favors the genetic isolation associated with chromosomal changes remains elusive. In this sense, the genus Mazama is recognized by its high level of karyotype diversity among species with similar morphology. A cryptic species complex has been identified within the genus, with the red brocket deer (Mazama americana and Mazama rufa) being the most impressive example. The chromosome variation was clustered in cytotypes with diploid numbers ranging from 42 to 53 and was correlated with geographical location. We conducted an analysis of chromosome evolution of the red brocket deer complex using comparative chromosome painting and Bacterial Artificial Chromosome (BAC) clones among different cytotypes. The aim was to deepen our understanding of the karyotypic relationships within the red brocket, thereby elucidating the significant chromosome variation among closely related species. This underscores the significance of chromosome changes as a key evolutionary process shaping their genomes. The results revealed the presence of three distinct cytogenetic lineages characterized by significant karyotypic divergence, suggesting the existence of efficient post-zygotic barriers. Tandem fusions constitute the main mechanism driving karyotype evolution, following a few centric fusions, inversion X-autosomal fusions. The BAC mapping has improved our comprehension of the karyotypic relationships within the red brocket deer complex, prompting questions regarding the role of these changes in the speciation process. We propose the red brocket as a model group to investigate how chromosomal changes contribute to isolation and explore the implications of these changes in taxonomy and conservation.
- MeSH
- karyotyp * MeSH
- karyotypizace * MeSH
- malování chromozomů MeSH
- molekulární evoluce * MeSH
- umělé bakteriální chromozomy genetika MeSH
- vysoká zvěř * genetika klasifikace MeSH
- vznik druhů (genetika) * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Miniature refers to species with extraordinarily small adult body size when adult and can be found within all major metazoan groups. It is considered that miniature species have experienced severe alteration of numerous morphological traits during evolution. For a variety of reasons, including severe labor concerns during collecting, chromosomal acquisition, and taxonomic issues, miniature fishes are neglected and understudied. Since some available studies indicate possible relationship between diploid chromosome number (2n) and body size in fishes, we aimed to study one of the smallest Neotropical fish Nannostomus anduzei (Teleostei, Characiformes, Lebiasinidae), using both conventional (Giemsa staining, C-banding) and molecular cytogenetic methods (FISH mapping of rDNAs, microsatellites, and telomeric sequences). Our research revealed that N. anduzei possesses one of the lowest diploid chromosome numbers (2n = 22) among teleost fishes, and its karyotype is entirely composed of large metacentric chromosomes. All chromosomes, except for pair number 11, showed an 18S rDNA signal in the pericentromeric region. 5S rDNA signals were detected in the pericentromeric regions of chromosome pair number 1 and 6, displaying synteny to 18S rDNA signals. Interstitial telomeric sites (ITS) were identified in the centromeric region of pairs 6 and 8, indicating that centric fusions played a significant role in karyotype evolution of studied species. Our study provides further evidence supporting the trend of diploid chromosome number reduction along with miniaturization of adult body size in fishes.
- MeSH
- Characiformes * genetika MeSH
- karyotyp MeSH
- karyotypizace MeSH
- ribozomální DNA genetika MeSH
- telomery genetika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Závěrečná zpráva o řešení grantu Agentury pro zdravotnický výzkum MZ ČR
nestr.
Život ohrožující kardiovaskulární komplikace (KV) signifikantně zkracují předpokládanou délku života u pacientek s Turnerovým syndromem (TS). Dosud nebyla jednoznačně definována genetická příčina KV onemocnění u TS. Cíle: Stanovení prevalence KV onemocnění u pacientek s Turnerovým syndromem rozdělených do podskupin dle cytogenetického nálezu; zhodnocení korelace KV rizika s karyotypem ze všech třech zárodečných listů; otestování hypotézy skrytého mozaicismu u TS. Metody: Do studie bude zahrnuto přibližně 100-150 pacientek s TS. Bude vyšetřen karyotyp ve všech třech zárodečných listech. Všechny nositelky TS podstoupí komplexní kardiologické vyšetření včetně magnetické rezonance (MRI) srdce. Závěr: Je pravděpodobné, že cytogenetické vyšetření hraje významnou roli při stratifikaci KV rizika u nositelek TS. Podrobné cytogenetické vyšetření spolu s MRI srdce by mohlo pomoci při identifikaci pacientek s nejvyšším KV rizikem a následně vést k individualizaci jejich kardiologického sledování.; Background: Life-threatening cardiovascular complications significantly reduce the life expectancy in patients with Turner syndrome (TS). The genetic basis of cardiovascular disease in TS has not been defined yet. Aims: To determine the prevalence of cardiovascular disease in different cytogenetic subgroups of TS; to find out which germ layer is the most appropriate for genetic prediction of the cardiovascular risk in TS; to test the hypothesis of hidden chromosomal mosaicism in all TS individuals. Methods: The study group will comprise of approximately 100 to 150 TS individuals. Karyotype in all three germ layers will be done. If TS diagnosed, all participants will undergo a complete cardiac examination including cardiac magnetic resonance imaging. Conclusion: It is suggested that the cytogenetic evaluation undoubtedly plays beside other risk factors an important role in cardiovascular risk stratification in TS. Such an approach may enable the identification of the highest risk patients and subsequent individualisation of their cardiovascular monitoring.
- MeSH
- bikuspidální aortální chlopeň MeSH
- disekce aorty MeSH
- kardiovaskulární nemoci epidemiologie genetika MeSH
- karyotyp MeSH
- karyotypizace MeSH
- koarktace aorty MeSH
- magnetická rezonanční tomografie MeSH
- mozaicismus MeSH
- rizikové faktory kardiovaskulárních chorob MeSH
- srdce diagnostické zobrazování MeSH
- Turnerův syndrom komplikace MeSH
- zárodečné listy MeSH
- Check Tag
- ženské pohlaví MeSH
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- genetika, lékařská genetika
- kardiologie
- epidemiologie
- NLK Publikační typ
- závěrečné zprávy o řešení grantu AZV MZ ČR
Cervids are characterized by their greatest karyotypic diversity among mammals. A great diversity of chromosome numbers in notably similar morphological groups leads to the existence of several complexes of cryptic species and taxonomic uncertainties. Some deer lineages, such as those of Neotropical deer, stand out for a rapid chromosomal reorganization and intraspecific chromosome polymorphisms, which have not been properly explored yet. For that reason, we contribute to the study of deer karyotype diversity and taxonomy by producing and characterizing new molecular cytogenetic markers for the gray brocket deer (Subulo gouazoubira), a deer species that retained the hypothetical ancestral karyotype of Cervidae. We used bacterial artificial chromosome (BAC) clones derived from the cattle genome (Bos taurus) as markers, which were hybridized on S. gouazoubira metaphase chromosomes. In total, we mapped 108 markers, encompassing all gray brocket deer chromosomes, except the Y chromosome. The detailed analysis of fluorescent in situ hybridization results showed 6 fissions and 1 fusion as interchromosomal rearrangements that have separated cattle and gray brocket deer karyotypes. Each group of BAC probes derived from bovine chromosome pairs 1, 2, 5, 6, 8, and 9 showed hybridization signals on 2 different chromosomes, while pairs 28 and 26 are fused in tandem in a single acrocentric chromosome in S. gouazoubira. Furthermore, the BAC markers detected the occurrence of intrachromosomal rearrangements in the S. gouazoubira chromosomes homologous to pair 1 and the X chromosome of cattle. We present a karyotypic map of the 108 new markers, which will be of great importance for future karyotypic evolution studies in cervids and, consequently, help in their conservation and taxonomy resolution.
BACKGROUND: In Turner syndrome (TS), fluorescent in situ hybridization (FISH) karyotyping offers an alternative to classical karyotyping. OBJECTIVE: We tested the added value of FISH karyotyping from lymphocytes (mesodermal origin), buccal cells (ectodermal origin), and a rear-tongue smear (endodermal origin) to determine the 45,X cell line fraction and its impact on patient phenotype. DESIGN AND PATIENTS: Classical karyotyping and three FISH assays were done in 153 girls and women previously diagnosed with TS in four university hospitals. The 45,X cell line fraction was determined for each method and correlated with the major phenotypic signs. RESULTS: Classical karyotyping identified 45,X/46,XX mosaicism in 77/153 subjects (50%), 45,X monosomy in 52/153 (34%), and other karyotypes in 24/153 (16%). FISH from lymphocytes verified 45,X in 47/52 original cases, whereas 4/52 had 45,X/46,XX and 1/52 45,X/47,XYY mosaicism. The 45,X cell line fraction was higher in FISH from lymphocytes compared to classical karyotyping (median 86.4% vs. 70.0%; p < 0.001), while there was no difference for FISH from buccal or rear-tongue smear cells. The mean 45,X cell line fraction was more abundant in patients with several of the characteristic phenotypic signs compared to patients without them (p < 0.01), but the predictive power was insufficient. CONCLUSION: FISH analysis confirmed the findings of classical karyotyping; only a few 45,X monosomy cases were reclassified as mosaics. The 45,X cell line fraction did not show clinically meaningful prediction of the phenotype. FISH analysis of buccal or rear-tongue epithelial cells may be a non-inferior, less invasive alternative to classical karyotyping.
Transcriptome sequencing (RNA-seq) is widely used to detect gene rearrangements and quantitate gene expression in acute lymphoblastic leukemia (ALL), but its utility and accuracy in identifying copy number variations (CNVs) has not been well described. CNV information inferred from RNA-seq can be highly informative to guide disease classification and risk stratification in ALL due to the high incidence of aneuploid subtypes within this disease. Here we describe RNAseqCNV, a method to detect large scale CNVs from RNA-seq data. We used models based on normalized gene expression and minor allele frequency to classify arm level CNVs with high accuracy in ALL (99.1% overall and 98.3% for non-diploid chromosome arms, respectively), and the models were further validated with excellent performance in acute myeloid leukemia (accuracy 99.8% overall and 99.4% for non-diploid chromosome arms). RNAseqCNV outperforms alternative RNA-seq based algorithms in calling CNVs in the ALL dataset, especially in samples with a high proportion of CNVs. The CNV calls were highly concordant with DNA-based CNV results and more reliable than conventional cytogenetic-based karyotypes. RNAseqCNV provides a method to robustly identify copy number alterations in the absence of DNA-based analyses, further enhancing the utility of RNA-seq to classify ALL subtype.
- MeSH
- algoritmy MeSH
- karyotypizace MeSH
- lidé MeSH
- sekvenování transkriptomu MeSH
- variabilita počtu kopií segmentů DNA * genetika MeSH
- vysoce účinné nukleotidové sekvenování * metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
We report on a major update to the animal rDNA loci database, which now contains cytogenetic information for 45S and 5S rDNA loci in more than 2600 and 1000 species, respectively.The data analyses show the following: (i) A high variability in 5S and 45S loci numbers, with both showing 50-fold or higher variability. However, karyotypes with an extremely high number of loci were rare, and medians generally converged to two 5S sites and two 45S rDNA sites per diploid genome. No relationship was observed between the number of 5S and 45S loci. (ii) The position of 45S rDNA on sex chromosomes was relatively frequent in some groups, particularly in arthropods (14% of karyotypes). Furthermore, 45S rDNA was almost exclusively located in microchromosomes when these were present (in birds and reptiles). (iii) The proportion of active NORs (positively stained with silver staining methods) progressively decreased with an increasing number of 45S rDNA loci, and karyotypes with more than 12 loci showed, on average, less than 40% of active loci. In conclusion, the updated version of the database provides some new insights into the organization of rRNA genes in chromosomes. We expect that its updated content will be useful for taxonomists, comparative cytogeneticists, and evolutionary biologists. .
The widely distributed ray-finned fish genus Carassius is very well known due to its unique biological characteristics such as polyploidy, clonality, and/or interspecies hybridization. These biological characteristics have enabled Carassius species to be successfully widespread over relatively short period of evolutionary time. Therefore, this fish model deserves to be the center of attention in the research field. Some studies have already described the Carassius karyotype, but results are inconsistent in the number of morphological categories for individual chromosomes. We investigated three focal species: Carassius auratus, C. carassius and C. gibelio with the aim to describe their standardized diploid karyotypes, and to study their evolutionary relationships using cytogenetic tools. We measured length (q+plength) of each chromosome and calculated centromeric index (i value). We found: (i) The relationship between q+plength and i value showed higher similarity of C. auratus and C. carassius. (ii) The variability of i value within each chromosome expressed by means of the first quartile (Q1) up to the third quartile (Q3) showed higher similarity of C. carassius and C. gibelio. (iii) The fluorescent in situ hybridization (FISH) analysis revealed higher similarity of C. auratus and C. gibelio. (iv) Standardized karyotype formula described using median value (Q2) showed differentiation among all investigated species: C. auratus had 24 metacentric (m), 40 submetacentric (sm), 2 subtelocentric (st), 2 acrocentric (a) and 32 telocentric (T) chromosomes (24m+40sm+2st+2a+32T); C. carassius: 16m+34sm+8st+42T; and C. gibelio: 16m+22sm+10st+2a+50T. (v) We developed R scripts applicable for the description of standardized karyotype for any other species. The diverse results indicated unprecedented complex genomic and chromosomal architecture in the genus Carassius probably influenced by its unique biological characteristics which make the study of evolutionary relationships more difficult than it has been originally postulated.
- MeSH
- chromozomy genetika MeSH
- diploidie MeSH
- fylogeneze MeSH
- genetická variace genetika MeSH
- genom genetika MeSH
- hybridizace in situ fluorescenční metody MeSH
- kapři genetika MeSH
- karas zlatý genetika MeSH
- karyotyp MeSH
- karyotypizace metody MeSH
- mapování chromozomů metody MeSH
- polyploidie MeSH
- ryby genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Duckweeds represent a small, free-floating aquatic family (Lemnaceae) of the monocot order Alismatales with the fastest growth rate among flowering plants. They comprise five genera (Spirodela, Landoltia, Lemna, Wolffiella, and Wolffia) varying in genome size and chromosome number. Spirodela polyrhiza had the first sequenced duckweed genome. Cytogenetic maps are available for both species of the genus Spirodela (S. polyrhiza and S. intermedia). However, elucidation of chromosome homeology and evolutionary chromosome rearrangements by cross-FISH using Spirodela BAC probes to species of other duckweed genera has not been successful so far. We investigated the potential of chromosome-specific oligo-FISH probes to address these topics. We designed oligo-FISH probes specific for one S. intermedia and one S. polyrhiza chromosome (Fig. 1a). Our results show that these oligo-probes cross-hybridize with the homeologous regions of the other congeneric species, but are not suitable to uncover chromosomal homeology across duckweeds genera. This is most likely due to too low sequence similarity between the investigated genera and/or too low probe density on the target genomes. Finally, we suggest genus-specific design of oligo-probes to elucidate chromosome evolution across duckweed genera.
- MeSH
- Araceae klasifikace genetika růst a vývoj MeSH
- chromozomy rostlin genetika MeSH
- druhová specificita MeSH
- fylogeneze MeSH
- genom rostlinný * MeSH
- hybridizace in situ fluorescenční metody MeSH
- karyotypizace MeSH
- molekulární evoluce * MeSH
- oligonukleotidové sondy chemie genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
