• MeSH
• Cytogenetics MeSH
• Terminology as Topic MeSH

• Conspectus
• Obecná genetika. Obecná cytogenetika. Evoluce
• NML Fields
• cytologie, klinická cytologie
• genetika, lékařská genetika
• NML Publication type
• kolektivní monografie

Although the impact of telomeres on physiology stands well established, a question remains: how do telomeres impact cellular functions at a molecular level? This is because current understanding limits the influence of telomeres to adjacent subtelomeric regions despite the wide-ranging impact of telomeres. Emerging work in two distinct aspects offers opportunities to bridge this gap. First, telomere-binding factors were found with non-telomeric functions. Second, locally induced DNA secondary structures called G-quadruplexes are notably abundant in telomeres, and gene regulatory regions genome wide. Many telomeric factors bind to G-quadruplexes for non-telomeric functions. Here we discuss a more general model of how telomeres impact the non-telomeric genome - through factors that associate at telomeres and genome wide - and influence cell-intrinsic functions, particularly aging, cancer, and pluripotency.

• MeSH
• DNA metabolism   MeSH
• G-Quadruplexes * MeSH
• Heterochromatin MeSH
• Telomere * genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

• MeSH
• Cytogenetics * MeSH
• Genomics * MeSH
• Publication type
• Terminology MeSH

• Conspectus
• Lékařské vědy. Lékařství
• NML Fields
• genetika, lékařská genetika

KEY MESSAGE: Fluorescence in situ hybridization with probes for 45 cDNAs and five tandem repeats revealed homoeologous relationships of Agropyron cristatum with wheat. The results will contribute to alien gene introgression in wheat improvement. Crested wheatgrass (Agropyron cristatum L. Gaertn.) is a wild relative of wheat and a promising source of novel genes for wheat improvement. To date, identification of A. cristatum chromosomes has not been possible, and its molecular karyotype has not been available. Furthermore, homoeologous relationship between the genomes of A. cristatum and wheat has not been determined. To develop chromosome-specific landmarks, A. cristatum genomic DNA was sequenced, and new tandem repeats were discovered. Their distribution on mitotic chromosomes was studied by fluorescence in situ hybridization (FISH), which revealed specific patterns for five repeats in addition to 5S and 45S ribosomal DNA and rye subtelomeric repeats pSc119.2 and pSc200. FISH with one tandem repeat together with 45S rDNA enabled identification of all A. cristatum chromosomes. To analyze the structure and cross-species homoeology of A. cristatum chromosomes with wheat, probes for 45 mapped wheat cDNAs covering all seven chromosome groups were localized by FISH. Thirty-four cDNAs hybridized to homoeologous chromosomes of A. cristatum, nine hybridized to homoeologous and non-homoeologous chromosomes, and two hybridized to unique positions on non-homoeologous chromosomes. FISH using single-gene probes revealed that the wheat-A. cristatum collinearity was distorted, and important structural rearrangements were observed for chromosomes 2P, 4P, 5P, 6P and 7P. Chromosomal inversions were found for pericentric region of 4P and whole chromosome arm 6PL. Furthermore, reciprocal translocations between 2PS and 4PL were detected. These results provide new insights into the genome evolution within Triticeae and will facilitate the use of crested wheatgrass in alien gene introgression into wheat.

• MeSH
• Agropyron genetics   MeSH
• Chromosomes, Plant * MeSH
• Diploidy MeSH
• DNA Probes MeSH
• In Situ Hybridization, Fluorescence MeSH
• Karyotype * MeSH
• Triticum genetics   MeSH
• Tandem Repeat Sequences * MeSH
• Translocation, Genetic MeSH
• Publication type
• Journal Article MeSH

Seabuckthorn (Hippophae rhamnoides) is a dioecious shrub commonly used in the pharmaceutical, cosmetic, and environmental industry as a source of oil, minerals and vitamins. In this study, we analyzed the transposable elements and satellites in its genome. We carried out Illumina DNA sequencing and reconstructed the main repetitive DNA sequences. For data analysis, we developed a new bioinformatics approach for advanced satellite DNA analysis and showed that about 25% of the genome consists of satellite DNA and about 24% is formed of transposable elements, dominated by Ty3/Gypsy and Ty1/Copia LTR retrotransposons. FISH mapping revealed X chromosome-accumulated, Y chromosome-specific or both sex chromosomes-accumulated satellites but most satellites were found on autosomes. Transposable elements were located mostly in the subtelomeres of all chromosomes. The 5S rDNA and 45S rDNA were localized on one autosomal locus each. Although we demonstrated the small size of the Y chromosome of the seabuckthorn and accumulated satellite DNA there, we were unable to estimate the age and extent of the Y chromosome degeneration. Analysis of dioecious relatives such as Shepherdia would shed more light on the evolution of these sex chromosomes.

• MeSH
• Chromosomes, Plant * MeSH
• DNA, Plant genetics   MeSH
• Phylogeny MeSH
• Genome, Plant MeSH
• Hippophae genetics   MeSH
• Evolution, Molecular MeSH
• Sex Chromosomes * MeSH
• DNA, Satellite * MeSH
• Sequence Analysis, DNA methods   MeSH
• DNA Transposable Elements * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

FISH is a useful method to identify individual chromosomes in a karyotype and to discover their structural changes accompanying genome evolution and speciation. DNA probes for FISH should be chromosome specific and/or exhibit specific patterns of distribution along each chromosome. Such probes are not available in many plants including meadow fescue (Festuca pratensis Huds.), an important forage grass species. In the present study, various DNA repeats identified in Illumina shotgun sequences specific to chromosome 4F of F. pratensis were used as probes for FISH to develop the molecular karyotype of meadow fescue and to reveal a long-range molecular organization of its chromosomes. Five tandem repeats produced specific patterns on individual chromosomes. Their use in combination with probes for rRNA genes enabled the establishment of the molecular karyotype of meadow fescue. Most of the mobile genetic elements were dispersed along all the chromosomes except for the DNA transposon CACTA, which was localized preferentially to telomeric and subtelomeric regions, and a putative LTR element, which was localized to (peri)centromeric regions. Cytogenetic mapping of the 5 tandem repeats in other accessions of meadow fescue showed a highly similar distribution and confirmed the versatility and robustness of these probes.

• MeSH
• Chromosomes, Plant MeSH
• DNA, Plant MeSH
• Festuca genetics   MeSH
• Phylogeny MeSH
• In Situ Hybridization, Fluorescence MeSH
• Karyotype MeSH
• Karyotyping methods   MeSH
• Tandem Repeat Sequences * MeSH
• Publication type
• Journal Article MeSH

• MeSH
• Chromosomes MeSH
• Cytogenetics MeSH
• Genomics MeSH
• Terminology as Topic MeSH

• Conspectus
• Patologie. Klinická medicína.
• NML Fields
• genetika, lékařská genetika
• NML Publication type
• kolektivní monografie

• Publication type
• Monograph MeSH

BACKGROUND: A prominent and distinctive feature of the rye (Secale cereale) chromosomes is the presence of massive blocks of subtelomeric heterochromatin, the size of which is correlated with the copy number of tandem arrays. The rapidity with which these regions have formed over the period of speciation remains unexplained. RESULTS: Using a BAC library created from the short arm telosome of rye chromosome 1R we uncovered numerous arrays of the pSc200 and pSc250 tandem repeat families which are concentrated in subtelomeric heterochromatin and identified the adjacent DNA sequences. The arrays show significant heterogeneity in monomer organization. 454 reads were used to gain a representation of the expansion of these tandem repeats across the whole rye genome. The presence of multiple, relatively short monomer arrays, coupled with the mainly star-like topology of the monomer phylogenetic trees, was taken as indicative of a rapid expansion of the pSc200 and pSc250 arrays. The evolution of subtelomeric heterochromatin appears to have included a significant contribution of illegitimate recombination. The composition of transposable elements (TEs) within the regions flanking the pSc200 and pSc250 arrays differed markedly from that in the genome a whole. Solo-LTRs were strongly enriched, suggestive of a history of active ectopic exchange. Several DNA motifs were over-represented within the LTR sequences. CONCLUSION: The large blocks of subtelomeric heterochromatin have arisen from the combined activity of TEs and the expansion of the tandem repeats. The expansion was likely based on a highly complex network of recombination mechanisms.

• MeSH
• Gene Amplification * MeSH
• Chromosomes, Plant genetics   MeSH
• Phylogeny MeSH
• Gene Library MeSH
• Heterochromatin genetics   MeSH
• In Situ Hybridization, Fluorescence MeSH
• Genome Components MeSH
• Sequence Analysis, DNA MeSH
• Oligonucleotide Array Sequence Analysis MeSH
• Tandem Repeat Sequences * MeSH
• DNA Transposable Elements * MeSH
• Chromosomes, Artificial, Bacterial MeSH
• Secale genetics   MeSH
• Publication type
• Journal Article MeSH

• MeSH
• Genetic Diseases, Inborn diagnosis   etiology   genetics   classification   MeSH
• Congenital, Hereditary, and Neonatal Diseases and Abnormalities diagnosis   etiology   genetics   classification   MeSH

• Conspectus
• Patologie. Klinická medicína
• NML Fields
• genetika, lékařská genetika
• embryologie a teratologie
• NML Publication type
• kolektivní monografie