MOTIVATION: The role of repetitive DNA in the 3D organization of the interphase nucleus is a subject of intensive study. In studies of 3D nucleus organization, mutual contacts of various loci can be identified by Hi-C sequencing. Typical analyses use binning of read pairs by location to reduce noise. We use binning by repeat families instead to make similar conclusions about repeat regions. RESULTS: To achieve this, we combined Hi-C data, reference genome data and tools for repeat analysis into a Nextflow pipeline identifying and quantifying the contacts of specific repeat families. As an output, our pipeline produces heatmaps showing contact frequency and circular diagrams visualizing repeat contact localization. Using our pipeline with tomato data, we revealed the preferential homotypic interactions of ribosomal DNA, centromeric satellites and some LTR retrotransposon families and, as expected, little contact between organellar and nuclear DNA elements. While the pipeline can be applied to any eukaryotic genome, results in plants provide better coverage, since the built-in TE-greedy-nester software only detects tandems and LTR retrotransposons. Other repeats can be fed via GFF3 files. This pipeline represents a novel and reproducible way to analyze the role of repetitive elements in the 3D organization of genomes. AVAILABILITY AND IMPLEMENTATION: https://gitlab.fi.muni.cz/lexa/hic-te/. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

• MeSH
• analýza dat * MeSH
• genom MeSH
• genomika * metody   MeSH
• retroelementy MeSH
• software MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• retroelementy MeSH

Diplomonads are anaerobic, flagellated protists, being part of the Metamonada group of Eukaryotes. Diplomonads either live as endobionts (parasites and commensals) of animals or free-living in low-oxygen environments. Genomic information is available for parasitic diplomonads like Giardia intestinalis and Spironucleus salmonicida, while little is known about the genomic arrangements of free-living diplomonads. We have generated the first reference genome of a free-living diplomonad, Hexamita inflata. The final version of the genome assembly is fragmented (1241 contigs) but substantially larger (142 Mbp) than the parasitic diplomonad genomes (9.8-14.7 Mbp). It encodes 79,341 proteins; 29,874 have functional annotations and 49,467 are hypothetical proteins. Interspersed repeats comprise 34% of the genome (9617 Retroelements, 2676 DNA transposons). The large expansion of protein-encoding capacity and the interspersed repeats are the major reasons for the large genome size. This genome from a free-living diplomonad will be the basis for further studies of the Diplomonadida lineage and the evolution of parasitism-free living style transitions.

• MeSH
• Diplomonadida * genetika   MeSH
• genom protozoální * MeSH
• retroelementy MeSH
• rozptýlené repetitivní sekvence MeSH
• Publikační typ
• časopisecké články MeSH
• dataset MeSH
• Názvy látek
• retroelementy MeSH

MOTIVATION: Transposable elements (TEs) in eukaryotes often get inserted into one another, forming sequences that become a complex mixture of full-length elements and their fragments. The reconstruction of full-length elements and the order in which they have been inserted is important for genome and transposon evolution studies. However, the accumulation of mutations and genome rearrangements over evolutionary time makes this process error-prone and decreases the efficiency of software aiming to recover all nested full-length TEs. RESULTS: We created software that uses a greedy recursive algorithm to mine increasingly fragmented copies of full-length LTR retrotransposons in assembled genomes and other sequence data. The software called TE-greedy-nester considers not only sequence similarity but also the structure of elements. This new tool was tested on a set of natural and synthetic sequences and its accuracy was compared to similar software. We found TE-greedy-nester to be superior in a number of parameters, namely computation time and full-length TE recovery in highly nested regions. AVAILABILITY AND IMPLEMENTATION: http://gitlab.fi.muni.cz/lexa/nested. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

• MeSH
• algoritmy MeSH
• molekulární evoluce MeSH
• retroelementy * genetika   MeSH
• software * MeSH
• transpozibilní elementy DNA MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• retroelementy * MeSH
• transpozibilní elementy DNA MeSH

BACKGROUND AND AIMS: Plant evolution is well known to be frequently associated with remarkable changes in genome size and composition; however, the knowledge of long-term evolutionary dynamics of these processes still remains very limited. Here a study is made of the fine dynamics of quantitative genome evolution in Festuca (fescue), the largest genus in Poaceae (grasses). METHODS: Using flow cytometry (PI, DAPI), measurements were made of DNA content (2C-value), monoploid genome size (Cx-value), average chromosome size (C/n-value) and cytosine + guanine (GC) content of 101 Festuca taxa and 14 of their close relatives. The results were compared with the existing phylogeny based on ITS and trnL-F sequences. KEY RESULTS: The divergence of the fescue lineage from related Poeae was predated by about a 2-fold monoploid genome and chromosome size enlargement, and apparent GC content enrichment. The backward reduction of these parameters, running parallel in both main evolutionary lineages of fine-leaved and broad-leaved fescues, appears to diverge among the existing species groups. The most dramatic reductions are associated with the most recently and rapidly evolving groups which, in combination with recent intraspecific genome size variability, indicate that the reduction process is probably ongoing and evolutionarily young. This dynamics may be a consequence of GC-rich retrotransposon proliferation and removal. Polyploids derived from parents with a large genome size and high GC content (mostly allopolyploids) had smaller Cx- and C/n-values and only slightly deviated from parental GC content, whereas polyploids derived from parents with small genome and low GC content (mostly autopolyploids) generally had a markedly increased GC content and slightly higher Cx- and C/n-values. CONCLUSIONS: The present study indicates the high potential of general quantitative characters of the genome for understanding the long-term processes of genome evolution, testing evolutionary hypotheses and their usefulness for large-scale genomic projects. Taken together, the results suggest that there is an evolutionary advantage for small genomes in Festuca.

• MeSH
• Festuca genetika   MeSH
• fylogeneze MeSH
• genom rostlinný * MeSH
• molekulární evoluce * MeSH
• polyploidie MeSH
• retroelementy MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• retroelementy MeSH

Silene latifolia is a dioecious plant species with chromosomal sex determination. Although the evolution of sex chromosomes in S. latifolia has been the subject of numerous studies, a global view of X chromosome structure in this species is still missing. Here, we combine X chromosome microdissection and BAC library screening to isolate new X chromosome-linked sequences. Out of 8 identified BAC clones, only BAC 86M14 showed an X-preferential signal after FISH experiments. Further analysis revealed the existence of the Athila retroelement which is enriched in the X chromosome and nearly absent in the Y chromosome. Based on previous data, the Athila retroelement belongs to the CL3 group of most repetitive sequences in the S. latifolia genome. Structural, transcriptomics and phylogenetic analyses revealed that Athila CL3 represents an old clade in the Athila lineage. We propose a mechanism responsible for Athila CL3 distribution in the S. latifolia genome.

• MeSH
• chromozomy rostlin genetika   MeSH
• fylogeneze MeSH
• pohlavní chromozomy genetika   MeSH
• retroelementy genetika   MeSH
• Silene genetika   MeSH
• transkriptom genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• retroelementy MeSH

BACKGROUND AND AIMS: Dioecious species with well-established sex chromosomes are rare in the plant kingdom. Most sex chromosomes increase in size but no comprehensive analysis of the kind of sequences that drive this expansion has been presented. Here we analyse sex chromosome structure in common sorrel (Rumex acetosa), a dioecious plant with XY1Y2 sex determination, and we provide the first chromosome-specific repeatome analysis for a plant species possessing sex chromosomes. METHODS: We flow-sorted and separately sequenced sex chromosomes and autosomes in R. acetosa using the two-dimensional fluorescence in situ hybridization in suspension (FISHIS) method and Illumina sequencing. We identified and quantified individual repeats using RepeatExplorer, Tandem Repeat Finder and the Tandem Repeats Analysis Program. We employed fluorescence in situ hybridization (FISH) to analyse the chromosomal localization of satellites and transposons. KEY RESULTS: We identified a number of novel satellites, which have, in a fashion similar to previously known satellites, significantly expanded on the Y chromosome but not as much on the X or on autosomes. Additionally, the size increase of Y chromosomes is caused by non-long terminal repeat (LTR) and LTR retrotransposons, while only the latter contribute to the enlargement of the X chromosome. However, the X chromosome is populated by different LTR retrotransposon lineages than those on Y chromosomes. CONCLUSIONS: The X and Y chromosomes have significantly diverged in terms of repeat composition. The lack of recombination probably contributed to the expansion of diverse satellites and microsatellites and faster fixation of newly inserted transposable elements (TEs) on the Y chromosomes. In addition, the X and Y chromosomes, despite similar total counts of TEs, differ significantly in the representation of individual TE lineages, which indicates that transposons proliferate preferentially in either the paternal or the maternal lineage.

• Klíčová slova
• Rumex acetosa, genome dynamics, satellites, sex chromosomes, transposable elements,
• MeSH
• chromozomy rostlin MeSH
• hybridizace in situ fluorescenční MeSH
• molekulární evoluce MeSH
• pohlavní chromozomy MeSH
• retroelementy MeSH
• Rumex * genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• retroelementy MeSH

Matthiola incana, commonly known as stock and gillyflower, is a widely grown ornamental plant whose genome is significantly larger than that of other species in the mustard family. However, the evolutionary history behind such a large genome (~2 Gb) is still unknown. Here, we have succeeded in obtaining a high-quality chromosome-scale genome assembly of M. incana by integrating PacBio HiFi reads, Illumina short reads and Hi-C data. The resulting genome consists of seven pseudochromosomes with a length of 1965 Mb and 38 245 gene models. Phylogenetic analysis indicates that M. incana and other taxa of the supertribe Hesperodae represent an early-diverging lineage in the evolutionary history of the Brassicaceae. Through a comparative analysis, we revisited the ancestral Hesperodae karyotype (AHK, n = 7) and found several differences from the well-established ancestral crucifer karyotype (ACK, n = 8) model, including extensive inter- and intra-chromosomal rearrangements. Our results suggest that the primary reason for genome obesity in M. incana is the massive expansion of long terminal repeat retrotransposons (LTR-RTs), particularly from the Angela, Athila and Retand families. CHG methylation modification is obviously reduced in the regions where the highest density of Copia-type LTR-RTs and the lowest density of Gypsy-type LTR-RTs overlap, corresponding to the putative centromeres. Based on insertion times and methylation profiling, recently inserted LTR-RTs were found to have a significantly different methylation pattern compared to older ones.

• Klíčová slova
• Cruciferae, Hesperodae, Lineage III, genome assembly, genome obesity, retrotransposons,
• MeSH
• Brassicaceae * genetika   MeSH
• chromozomy rostlin genetika   MeSH
• fylogeneze MeSH
• genom rostlinný * genetika   MeSH
• karyotyp MeSH
• molekulární evoluce * MeSH
• retroelementy * genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• retroelementy * MeSH

Over a half of mammalian genomes is occupied by repetitive elements whose ability to provide functional sequences, move into new locations, and recombine underlies the so-called genome plasticity. At the same time, mobile elements exemplify selfish DNA, which is expanding in the genome at the expense of the host. The selfish generosity of mobile genetic elements is in the center of research interest as it offers insights into mechanisms underlying evolution and emergence of new genes. In terms of numbers, with over 20,000 in count, protein-coding genes make an outstanding >2 % minority. This number is exceeded by an ever-growing list of genes producing long non-coding RNAs (lncRNAs), which do not encode for proteins. LncRNAs are a dynamically evolving population of genes. While it is not yet clear what fraction of lncRNAs represents functionally important ones, their features imply that many lncRNAs emerge at random as new non-functional elements whose functionality is acquired through natural selection. Here, we explore the intersection of worlds of mobile genetic elements (particularly retrotransposons) and lncRNAs. In addition to summarizing essential features of mobile elements and lncRNAs, we focus on how retrotransposons contribute to lncRNA evolution, structure, and function in mammals.

• Klíčová slova
• LINE, LTR, MaLR, Retrotransposon, SINE, lncRNA,
• MeSH
• lidé MeSH
• molekulární evoluce MeSH
• myši MeSH
• retroelementy genetika   MeSH
• RNA dlouhá nekódující genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• retroelementy MeSH
• RNA dlouhá nekódující MeSH

Improved knowledge of genome composition, especially of its repetitive component, generates important information for both theoretical and applied research. The olive repetitive component is made up of two main classes of sequences: tandem repeats and retrotransposons (REs). In this study, we provide characterization of a sample of 254 unique full-length long terminal repeat (LTR) REs. In the sample, Ty1-Copia elements were more numerous than Ty3-Gypsy elements. Mapping a large set of Illumina whole-genome shotgun reads onto the identified retroelement set revealed that Gypsy elements are more redundant than Copia elements. The insertion time of intact retroelements was estimated based on sister LTR's divergence. Although some elements inserted relatively recently, the mean insertion age of the isolated retroelements is around 18 million yrs. Gypsy and Copia retroelements showed different waves of transposition, with Gypsy elements especially active between 10 and 25 million yrs ago and nearly inactive in the last 7 million yrs. The occurrence of numerous solo-LTRs related to isolated full-length retroelements was ascertained for two Gypsy elements and one Copia element. Overall, the results reported in this study show that RE activity (both retrotransposition and DNA loss) has impacted the olive genome structure in more ancient times than in other angiosperms.

• Klíčová slova
• BAC sequencing, LTR retrotransposons, insertion age, next-generation sequencing, olive,
• MeSH
• celogenomová asociační studie * MeSH
• koncové repetice * MeSH
• mapování chromozomů * MeSH
• Olea genetika   MeSH
• retroelementy * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• retroelementy * MeSH

The centromere has a conserved function across eukaryotes; however, the associated DNA sequences exhibit remarkable diversity in both size and structure. In plants, some species possess well-defined centromeres dominated by tandem satellite repeats and centromeric retrotransposons, while others have centromeric regions composed almost entirely of retrotransposons. Using a combination of bioinformatic, molecular, and cytogenetic approaches, we analyzed the centromeric landscape of Humulus lupulus. We identified novel centromeric repeats and characterized two types of centromeric organization. Cytogenetic localization on metaphase chromosomes confirmed the genomic distribution of the major repeats and revealed unique centromeric organization specifically on chromosomes 2, 8, and Y. Two centromeric types are composed of the major repeats SaazCEN and SaazCRM1 (Ty3/Gypsy) which are further accompanied by chromosome-specific centromeric satellites, Saaz40, Saaz293, Saaz85, and HuluTR120. Chromosome 2 displays unbalanced segregation during mitosis and meiosis, implicating an important role for its centromere structure in segregation patterns. Moreover, chromosome 2-specific centromeric repeat Saaz293 is a new marker for studying aneuploidy in hops. Our findings provide new insights into chromosome segregation in hops and highlight the diversity and complexity of the centromere organization in H. lupulus.

• Klíčová slova
• Cannabaceae, asymmetric cell division, centromere, retrotransposons, sex chromosomes,
• MeSH
• centromera * genetika   MeSH
• chromozomy rostlin genetika   MeSH
• Humulus * genetika   MeSH
• meióza genetika   MeSH
• repetitivní sekvence nukleových kyselin * genetika   MeSH
• retroelementy * genetika   MeSH
• segregace chromozomů genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• retroelementy * MeSH