Molekularbiologische und Röntgenmikroskopische Charakterisierung der Heterochromatinproteine des Nematoden Caenorhabditis elegans
Bibliographic record
Abstract
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.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".