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"Point centromeres" bind to specific proteins that recognize particular DNA sequences with high efficiency. Any piece of DNA with the point centromere DNA sequence on it will typically form a centromere if present in the appropriate species. The best characterized point centromeres are those of the budding yeast, Saccharomyces cerevisiae ...
The human homolog, hsSgo1, associates with centromeres during prophase and disappears when anaphase starts. [74] When Shugoshin levels are reduced by RNAi in HeLa cells, cohesin cannot remain on the centromeres during mitosis, and consequently sister chromatids separate synchronically before anaphase initiates, which triggers a long mitotic arrest.
Chromatin diminution (founding father: Theodor Boveri). In this process, found in some copepods and roundworms such as Ascaris suum , portions of the chromosomes are cast away in particular cells. This process is a carefully organised genome rearrangement where new telomeres are constructed and certain heterochromatin regions are lost.
Retinoblastoma: A small percentage of retinoblastoma cases are caused by deletions in the region of chromosome 13 (13q14) containing the RB1 gene. [11] Children with these chromosomal deletions may also have intellectual disability, slow growth, and characteristic facial features (such as prominent eyebrows, a broad nasal bridge, a short nose ...
This level of chromatin structure is thought to be the form of heterochromatin, which contains mostly transcriptionally silent genes. Electron microscopy studies have demonstrated that the 30 nm fiber is highly dynamic such that it unfolds into a 10 nm fiber beads-on-a-string structure when transversed by an RNA polymerase engaged in transcription.
Extrachromosomal DNA found in cancer have historically been referred to as Double minute chromosomes (DMs), which present as paired chromatin bodies under light microscopy. Double minute chromosomes represent ~30% of the cancer-containing spectrum of ecDNA, including single bodies and have been found to contain identical gene content as single ...
Using an adenovirus vector for wild-type p53, human ovarian cancer cell line 2774qw1 (which expresses mutant p53) was transfected. mRNA levels of survivin were analyzed by real-time quantitative PCR and showed time-dependent down regulation of survivin mRNA levels when the cells were infected with wild-type p53. [17]
Bottom: Two tomato SCs with the chromatin removed, allowing kinetochores ("ball-like" structures) at centromeres to be revealed. The synaptonemal complex ( SC ) is a protein structure that forms between homologous chromosomes (two pairs of sister chromatids ) during meiosis and is thought to mediate synapsis and recombination during prophase I ...