ALKB-8 is a 2-oxoglutarate-dependent dioxygenase homologous to bacterial AlkB, which oxidatively demethylates DNA substrates. The mammalian AlkB family contains AlkB homologues denominated ALKBH1 to 8 and FTO. The C. elegans genome includes five AlkB-related genes, homologues of ALKBH1, 4, 6, 7, and 8, but lacks homologues of ALKBH2, 3, and 5 and FTO. ALKBH8 orthologues differ from other AlkB family members by possessing an additional methyltransferase module and an RNA binding N-terminal module. The ALKBH8 methyltransferase domain generates the wobble nucleoside 5-methoxycarbonylmethyluridine from its precursor 5-carboxymethyluridine and its (R)- and (S)-5-methoxycarbonylhydroxymethyluridine hydroxylated forms in tRNA Arg/UCG and tRNA Gly/UCC. The ALKBH8/ALKB-8 methyltransferase domain is highly similar to yeast TRM9, which selectively modulates translation of mRNAs enriched with AGA and GAA codons under both normal and stress conditions. In this report, we studied the role of alkb-8 in C. elegans. We show that downregulation of alkb-8 increases detection of lysosome-related organelles visualized by Nile red in vivo. Reversely, forced expression of alkb-8 strongly decreases the detection of this compartment. In addition, overexpression of alkb-8 applied in a pulse during the L1 larval stage increases the C. elegans lifespan.

• MeSH
• Caenorhabditis elegans embryologie   enzymologie   genetika   MeSH
• dioxygenasy metabolismus   MeSH
• dlouhověkost MeSH
• down regulace genetika   MeSH
• embryo nesavčí metabolismus   MeSH
• geneticky modifikovaná zvířata MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• larva metabolismus   MeSH
• lyzozomy metabolismus   MeSH
• methyltransferasy metabolismus   MeSH
• operon MeSH
• promotorové oblasti (genetika) MeSH
• proteiny Caenorhabditis elegans genetika   metabolismus   MeSH
• RNA interference MeSH
• S-adenosylmethionin metabolismus   MeSH
• stárnutí metabolismus   MeSH
• vývojová regulace genové exprese MeSH
• zelené fluorescenční proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Caenorhabditis elegans is a well-established model organism which allows, among others, to investigate the link between nucleolar structure/function on the one hand and cell fate choices and cellular differentiation on the other. In addition, C. elegans can be used to study the role of the nucleolus in processes that can be difficult to faithfully reproduce in vitro, such as gametogenesis, disease development, and aging. Here I present two complementary techniques, immunofluorescent staining and DNA fluorescence in situ hybridization, that have been adapted to label nucleolar components at various stages of the life cycle of the worm.

• MeSH
• buněčné jadérko genetika   metabolismus   MeSH
• Caenorhabditis elegans embryologie   genetika   MeSH
• DNA sondy MeSH
• DNA * MeSH
• embryonální vývoj genetika   MeSH
• fluorescenční protilátková technika * MeSH
• hybridizace in situ fluorescenční * MeSH
• konfokální mikroskopie MeSH
• ribozomální DNA genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The parental genomes are initially spatially separated in each pronucleus after fertilization. Here we have used green-to-red photoconversion of Dendra2-H2B-labeled pronuclei to distinguish maternal and paternal chromatin domains and to track their spatial distribution in living Caenorhabditis elegans embryos starting shortly after fertilization. Intermingling of the parental chromatin did not occur until after the division of the AB and P1 blastomeres, at the 4-cell stage. Unexpectedly, we observed that the intermingling of chromatin did not take place during mitosis or during chromatin decondensation, but rather ∼ 3-5 minutes into the cell cycle. Furthermore, unlike what has been observed in mammalian cells, the relative spatial positioning of chromatin domains remained largely unchanged during prometaphase in the early C. elegans embryo. Live imaging of photoconverted chromatin also allowed us to detect a reproducible 180° rotation of the nuclei during cytokinesis of the one-cell embryo. Imaging of fluorescently-labeled P granules and polar bodies showed that the entire embryo rotates during the first cell division. To our knowledge, we report here the first live observation of the initial separation and subsequent mixing of parental chromatin domains during embryogenesis.

• MeSH
• blastomery cytologie   metabolismus   MeSH
• buněčný cyklus MeSH
• Caenorhabditis elegans embryologie   genetika   metabolismus   MeSH
• časosběrné zobrazování metody   MeSH
• časové faktory MeSH
• chromatin genetika   metabolismus   MeSH
• embryo nesavčí cytologie   embryologie   metabolismus   MeSH
• fertilizace MeSH
• histony genetika   metabolismus   MeSH
• luminescentní proteiny genetika   metabolismus   MeSH
• mitóza MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

The development of complex multicellular organisms is dependent on regulatory decisions that are necessary for the establishment of specific differentiation and metabolic cellular states. Nuclear receptors (NRs) form a large family of transcription factors that play critical roles in the regulation of development and metabolism of Metazoa. Based on their DNA binding and ligand binding domains, NRs are divided into eight NR subfamilies from which representatives of six subfamilies are present in both deuterostomes and protostomes indicating their early evolutionary origin. In some nematode species, especially in Caenorhabditis, the family of NRs expanded to a large number of genes strikingly exceeding the number of NR genes in vertebrates or insects. Nematode NRs, including the multiplied Caenorhabditis genes, show clear relation to vertebrate and insect homologues belonging to six of the eight main NR subfamilies. This review summarizes advances in research of nematode NRs and their developmental functions. Nematode NRs can reveal evolutionarily conserved mechanisms that regulate specific developmental and metabolic processes as well as new regulatory adaptations. They represent the results of a large number of natural experiments with structural and functional potential of NRs for the evolution of the phylum. The conserved and divergent character of nematode NRs adds a new dimension to our understanding of the general biology of regulation by NRs. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

• MeSH
• Caenorhabditis elegans embryologie   genetika   MeSH
• hlístice embryologie   genetika   růst a vývoj   MeSH
• konzervovaná sekvence MeSH
• molekulární evoluce * MeSH
• receptory cytoplazmatické a nukleární klasifikace   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Cells belonging to the germ lineage segregate physically and molecularly from their somatic neighbors during embryogenesis. While germ line-specific chromatin modifications have been identified at later stages in the Caenorhabditis elegans nematode, none have been found in the single P4 germ line founder cell that arises at the beginning of gastrulation. Using light and electron microscopy, we now report that the chromatin organization in the germ line founder cell of the early C. elegans embryo is distinct from that in the neighboring somatic cells. This unique organization is characterized by a greater chromatin compaction and an expansion of the interchromatin compartment. The ultrastructure of individual chromatin domains does not differ between germ line and somatic cells, pointing to a specific organization mainly at the level of the whole nucleus. We show that this higher order reorganization of chromatin is not a consequence of the P4 nucleus being smaller than somatic nuclei or having initiated mitosis. Imaging of living embryos expressing fluorescent markers for both chromatin and P granules revealed that the appearance of a distinct chromatin organization in the P4 cell occurs approximately 10 min after its birth and coincides with the aggregation of P granules around the nucleus, suggesting a possible link between these two events. The higher order reorganization of chromatin that is reported here occurs during the establishment of definitive germ cell identity. The changes we have observed could therefore be a prerequisite for the programming of chromatin totipotency.

• MeSH
• Caenorhabditis elegans embryologie   ultrastruktura   MeSH
• chromatin metabolismus   ultrastruktura   MeSH
• embryo nesavčí metabolismus   ultrastruktura   MeSH
• restrukturace chromatinu fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

In the Caenorhabditis elegans nematode, the oocyte nucleolus disappears prior to fertilization. We have now investigated the re-formation of the nucleolus in the early embryo of this model organism by immunostaining for fibrillarin and DAO-5, a putative NOLC1/Nopp140 homolog involved in ribosome assembly. We find that labeled nucleoli first appear in somatic cells at around the 8-cell stage, at a time when transcription of the embryonic genome begins. Quantitative analysis of radial positioning showed the nucleolus to be localized at the nuclear periphery in a majority of early embryonic nuclei. At the ultrastructural level, the embryonic nucleolus appears to be composed of a relatively homogenous core surrounded by a crescent-shaped granular structure. Prior to embryonic genome activation, fibrillarin and DAO-5 staining is seen in numerous small nucleoplasmic foci. This staining pattern persists in the germline up to the ∼100-cell stage, until the P4 germ cell divides to give rise to the Z2/Z3 primordial germ cells and embryonic transcription is activated in this lineage. In the ncl-1 mutant, which is characterized by increased transcription of rDNA, DAO-5-labeled nucleoli are already present at the 2-cell stage. Our results suggest a link between the activation of transcription and the initial formation of nucleoli in the C. elegans embryo.

• MeSH
• buněčné jadérko genetika   metabolismus   ultrastruktura   MeSH
• Caenorhabditis elegans embryologie   genetika   ultrastruktura   MeSH
• embryo nesavčí embryologie   ultrastruktura   MeSH
• genetická transkripce fyziologie   MeSH
• genom u helmintů fyziologie   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• proteiny Caenorhabditis elegans genetika   metabolismus   MeSH
• vývojová regulace genové exprese fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• apoptóza genetika   MeSH
• Caenorhabditis elegans embryologie   genetika   metabolismus   MeSH
• genetická transkripce genetika   MeSH
• hormony štítné žlázy fyziologie   MeSH
• lidé MeSH
• proteiny Caenorhabditis elegans fyziologie   genetika   MeSH
• regulace genové exprese genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH