Expression of Transposable Elements throughout the Trematode Life Cycle.

Background: Transposable elements (TEs) are major components of eukaryotic genomes. The extensive body of evidence suggests that although they were once considered "genomic parasites", transposons and their transcripts perform specific functions, such as regulation of early embryo development. Understanding the role of TEs in such parasites as trematodes is becoming critically important.

New putative phenol oxidase in ascidian blood cells.

The phenol oxidase system is ancient and ubiquitously distributed in all living organisms. In various groups it serves for the biosynthesis of pigments and neurotransmitters (dopamine), defence reactions and tissue hardening. Ascidians belong to subphylum Tunicata, which is considered the closest living relative to Vertebrates.

Nuclear organization by satellite DNA, SAF-A/hnRNPU and matrix attachment regions.

The need of large-scale chromatin organization in the nucleus has become more and more appreciated. The higher order nuclear organization ultimately regulate a plethora of biological processes including transcription, DNA replication, and DNA repair. In this context, it is of critical importance to understand the mechanisms that allow higher order nuclear organization.

Tandem Repeat Diversity in Two Closely Related Hamster Species-The Chinese Hamster () and Striped Hamster ().

The Chinese hamster () and striped hamster () are very closely related species with similar karyotypes. The karyotypes differ from each other by one Robertsonian rearrangement and X-chromosome morphology. The level of the tandem repeat (TR) sequences' evolutional variability is high.

Novel protein from larval sponge cells, ilborin, is related to energy turnover and calcium binding and is conserved among marine invertebrates.

Sponges (phylum Porifera) are early-branching animals, whose outwardly simple body plan is underlain by a complex genetic repertoire. The transition from a mobile larva to an attached filter-feeding organism occurs by metamorphosis, a process accompanied by a radical change of the body plan and cell transdifferentiation. The continuity between larval cells and adult tissues is still obscure.

Transposons-Based Clonal Diversity in Trematode Involves Parts of CR1 (LINE) in Eu- and Heterochromatin.

Trematode parthenitae have long been believed to form clonal populations, but clonal diversity has been discovered in this asexual stage of the lifecycle. Clonal polymorphism in the model species has been previously described, but the source of this phenomenon remains unknown. In this work, we traced cercarial clonal diversity using a simplified amplified fragment length polymorphism (SAFLP) method and characterised the nature of fragments in diverse electrophoretic bands.

The Long Linker Region of Telomere-Binding Protein TRF2 Is Responsible for Interactions with Lamins.

Telomere-binding factor 2 (TRF2) is part of the shelterin protein complex found at chromosome ends. Lamin A/C interacts with TRF2 and influences telomere position. TRF2 has an intrinsically disordered region between the ordered dimerization and DNA-binding domains.

Tandem Repeat-Based Probes Support the Loop Model of Pericentromere Packing.

Constitutive heterochromatin is the most mysterious part of the eukaryotic genome. It forms vital chromosome regions such as the centromeric and the pericentromeric ones. The main component of heterochromatic regions are tandem repeats (TR), and their specific organization complicates assembly, annotation, and mapping of these regions.

Human pericentromeric tandemly repeated DNA is transcribed at the end of oocyte maturation and is associated with membraneless mitochondria-associated structures.

Most of the human genome is non-coding. However, some of the non-coding part is transcriptionally active. In humans, the tandemly repeated (TR) pericentromeric non-coding DNA-human satellites 2 and 3 (HS2, HS3)-are transcribed in somatic cells.

Amino acid sequence associated with bacteriophage recombination site helps to reveal genes potentially acquired through horizontal gene transfer.

Background: Horizontal gene transfer, i.e. the acquisition of genetic material from nonparent organism, is considered an important force driving species evolution.

Actin depolymerization disrupts karyosphere capsule integrity but not residual transcription in late oocytes of the grass frog Rana temporaria.

Late diplotene oocytes are characterized by an essential decrease in transcriptional activity. At this time, chromosomes condense and form a compact structure named a karyosphere. The karyosphere of grass frogs Rana temporaria is surrounded by a fibrillar karyosphere capsule (KC).

From traveler to homebody: Which signaling mechanisms sponge larvae use to become adult sponges?

Cell-to-cell signaling is responsible for regulation of many developmental processes such as proliferation, cell migration, survival, cell fate specification and axis patterning. In this article we discussed the role of signaling in the metamorphosis of sponges with a focus on epithelial-mesenchymal transition (EMT) accompanying this event. Sponges (Porifera) are an ancient lineage of morphologically simple animals occupying a basal position on the tree of life.

Features of a novel protein, rusticalin, from the ascidian reveal ancestral horizontal gene transfer event.

Background: The transfer of genetic material from non-parent organisms is called horizontal gene transfer (HGT). One of the most conclusive cases of HGT in metazoans was previously described for the cellulose synthase gene in ascidians.

Results: In this study we identified a new protein, rusticalin, from the ascidian and presented evidence for its likely origin by HGT.

The karyosphere capsule in Rana temporaria oocytes contains structural and DNA-binding proteins.

During the last stages of oogenesis, oocyte chromosomes condense and come close together, forming the so-called karyosphere. Karyosphere formation is accompanied by an essential decrease in transcriptional activity. In the grass frog Rana temporaria, the karyosphere is surrounded by an extrachromosomal capsule that separates the chromosomes from the rest of the nucleoplasm.

Who Needs This Junk, or Genomic Dark Matter.

Centromeres (CEN), pericentromeric regions (periCEN), and subtelomeric regions (subTel) comprise the areas of constitutive heterochromatin (HChr). Tandem repeats (TRs or satellite DNA) are the main components of HChr forming no less than 10% of the mouse and human genome. HChr is assembled within distinct structures in the interphase nuclei of many species - chromocenters.

Mouse chromocenters DNA content: sequencing and in silico analysis.

Background: Chromocenters are defined as a punctate condensed blocks of chromatin in the interphase cell nuclei of certain cell types with unknown biological significance. In recent years a progress in revealing of chromocenters protein content has been made although the details of DNA content within constitutive heterochromatin still remain unclear. It is known that these regions are enriched in tandem repeats (TR) and transposable elements.

The exon junction complex factor Y14 is dynamic in the nucleus of the beetle during late oogenesis.

Background: The oocyte chromosomes of the red flour beetle, , are gathered into a knot, forming a karyosphere at the diplotene stage of meiotic prophase. Chromatin rearrangement, which is a characteristic feature of oocyte maturation, is well documented. The karyosphere is surrounded by a complex extrachromosomal structure termed the karyosphere capsule.

Heterochromatic Tandem Repeats in the Extracellular DNA.

Only limited sequencing data of the normal extracellular DNA (ecDNA) are currently available. The uptake of the ecDNA by cultured cells and its integration into the host chromatin have been demonstrated. A number of membrane-bearing vesicles in plasma and serum have been shown to carry nucleic acids.

Genomic diversity of cercarial clones of Himasthla elongata (Trematoda, Echinostomatidae) determined with AFLP technique.

The aim of this study was to reveal genomic diversity formed during parthenogenetic reproduction of rediae of the trematode Himasthla elongata in its molluskan host Littorina littorea. We applied amplification fragment length polymorphism (AFLP) to determine the genomic diversity of individual cercariae within the clone, that is, the infrapopulation of parthenogenetic progeny in a single molluskan host. The level of genomic diversity of particular cercariae isolates from a single clone, detected with EcoR1/Mse1 AFLP reaction, was significantly lower than the variability of cercariae from different clones.

Karyotype features of trematode Himasthla elongata.

Background: Trematodes have a complex life cycle with animal host changes and alternation of parthenogenetic and hermaphrodite generations. The parthenogenetic generation of the worm (rediae) from the first intermediate host Littorina littorea was used for chromosome spreads production. Karyotype description of parasitic flatworm Himasthla elongata Mehlis, 1831 (Digenea: Himasthlidae) based on fluorochrome banding and 18S rDNA mapping.

LINE-related component of mouse heterochromatin and complex chromocenters' composition.

Chromocenters are interphase nuclear landmark structures of constitutive heterochromatin. The tandem repeat (TR)-enriched parts of different chromosomes cluster together in chromocenters. There has been progress in recent years in determining the protein content of chromocenters, although it is not clear which DNA sequences underly constitutive heterochromatin apart from the TRs.

THE KARYOSPHERE CAPSULE IN OOCYTES OF HIBERNATING FROGS RANA TEMPORARIA CONTAINS ACTIN, LAMINS AND SMALL NUCLEAR RNP.

The nuclei of late vitellogenic oocytes of hibernating frogs Rana temporaria were studied. During the studied period of oogenesis, chromosomes are significantly inactivated and surrounded by a fibrillar karyosphere capsule. Formation of the karyosphere capsule in the grass frog oocytes was previously investigated in detail at the light and electron microscopic levels, but the molecular composition of the capsule still remains uncertain.

THE STRUCTURE OF DNA CHROMOCENTRES IN MOUSE IN SILICO AND IN SITU. LINE AND ERV FRAGMENTS ARE AN OBLIGATORY COMPONENTS OF DNA CHROMOCENTRES BESIDES TANDEM REPEATS.

Constitutive heterochromatin in higher eukaryotes is located in the primary chromosomal strangulation (centromeres and pericentromeres) and subtelomeric regions of chromosomes. In house mouse constitutive chromatin formes structures in the nuclei of cells, brightly colored with DAPI. It is known that the constitutive heterochromatin is enriched with large tandem repeats, however, its exact composition is unknown.

EXTRA-CELLULAR DNA FOR THE UNSOLVED EVOLUTIONAL PROBLEMS.

The genome assembly and new sequencing methods shed light on extra-cellular DNA (ecDNA) content and uptake. The recent data are described. The asymmetry in repetitive sequences distribution in ecDNA are shown: 1) significant enrichment in pericentromeric tandem repeats (TR), but decrease of centromeric alpha-satellite; 2) enrichment in Alu (SINE) but decrease of LINEs.