Molekularbiologische und Röntgenmikroskopische Charakterisierung der Heterochromatinproteine des Nematoden Caenorhabditis elegans
Notice bibliographique
Résumé
The nematode C. elegans was the first multicellular organisms whose genome was completely sequenced (The C. elegans Sequencing Consortium, 1998). This model organism is highly eligible for a variety of approaches in developmental biology, genetics and biochemistry. For the first time, in this study the nematode C. elegans was used to investigate heterochromatin binding protein 1 (HP1) homologs in order to analyze their molecular functions. A sequence alignment revealed three HP1 homologs, HP1.1, HP1.2, and HP1.3 in the genome of C. elegans. HP1.3 was detected with an anti mouse-HP1 antibody. The nematode C. elegans is a model organism which can be used for genetical and biochemical approaches. The aim of this work was to explore the role of heterochromatin protein homologs in C. elegans. Extrachromosomal and integrated arrays expressions fluorescent fusion proteins of living specimen by HP1.1::GFP were created, which allowed the cytological observation with a confocal laser scanning microscope. The dynamics of the HP1.1 distribution throughout the cell cycle has been documented. The expression of HP1.1::GFP begins with the 60-cell stage in embryogenesis. HP1.1 is present in a very high number of cells in most of the tissues. Furthermore, there are mostly six spot-like subnuclear structures in the chromatin near to the nuclear envelope of interphase nuclei. These subnuclear structures disappear dynamically with the onset of mitosis, when the nuclear envelope breaks down. HP1.1 separates from chromosomes in the prometaphase completely, and relocates to chromosomes at late metaphase. At the anaphase HP1.1 occupies binding sites of the spindle-fibers as a layer. For concomitant visualization of HP1 and DNA a double-label experiment was used, in which H1.1::CFP serves as a indirect marker for DNA. I show that HP1.1 is part of the outer kinetochore of C. elegans holocentric chromosomes using images recorded with a confocal laser scanning microscope. dsRNA with HP1.1 expression showed multiple and variable defects including embryonic death, slow growth, dumpy-like animals, and larval arrest. The molecular mechanisms of HP1.1 localization to the spot-like structures in interphase were analyzed by dsRNA with established HP1 interacting proteins in the hp1.1::gfp reporter strain. dsRNA with the SET domain proteins SU(VAR)3-9 (C41G7.4), and another SET domain (C15H11.5) relocated HP1.1::GFP to the cytoplasm. dsRNA with the lamin B receptor (B0250.7) led to a diffuse intranuclear distribution of HP1.1::GFP in the nuclei. dsRNA with ORC2 (F59E10.1) expression resulted in misregulation of the quantity of HP1.1 expression and a modified intranuclear distribution. These results have given rise to interpretations that HP1.1 is involved in a number of different chromatin protein complexes. HP1.1 is not involved in the chromatin silencing in the germ line of C. elegans as shown by HP1.1 dsRNA experiments in a germline silenced reporter strain. This is additional and confirmed by the analysis of HP1.1 expression patterns. HP1.1 is involved in a number of different chromatin complexes which show that HP1.1 is a strictly somatic protein. The observations in this work indicate that at the molecular level HP1.1 in C. elegans functions in contrast to organisms which contain visible amounts of heterochromatin.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».