This is the Cavalli lab video channel. It features video abstracts describing scientific discoveries of our lab, which relate to our publications.
For a short intro on our interest, go to ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-5PEp1Ia4ROc.html. This video is in French, but you can add subtitles. For English subtitles, click the "cc" button on the bottom right, then click on the "settings" button on the bottom right, the select "subtitles", "Auto-translate", English.
For more information of our lab, go to: www.igh.cnrs.fr/en/research/departments/genome-dynamics/21-chromatin-and-cell-biology
For other media profiles of Giacomo Cavalli: Twitter: twitter.com/giacomo_cavalli - @giacomo_cavalli Google Scholar: scholar.google.com/citations?user=5oWMD9EAAAAJ&hl=en
Not applicable to humans. “Heritance” from somatic cells is far different from what occurs after meiosis in the germ cell line, and it is that cell line that is responsible for transgenerational “inheritance.” In mammals, all of the epigenetics changes are removed and restored back to baseline. The cysteine is demethylated, and the histone’s spatial orientation/morphology epigenetics changes removed, which I find fascinating but is indeed a fact and was a surprise which destroys transgenerational epigenetic theory in fact. This is actually done twice, once after inception and once after implantation. Therefore no prior epigenetic changes from parent will pass to child, barring an extremely rare mistake ie: the equivalence of a rare nucleotide substitution that occurs in a genetic mutation if you will. This has been and continues to be extensively studied, but there is no evidence that the parent’s epigenetic changes can be passed to the offspring. If I am wrong, please elaborate, because I find it potentially dangerous that people are extrapolating this unproven if not disproven theory to subjects that could have large societal implications.
Yes it is. Indeed, a frequent observation when inserting DNA sequences into the genome in order to express proteins is that the DNA can not be expressed, or is initially expressed but mRNA expression becomes silenced over time. This is frequently due to the packaging of chromosomal DNA into condensed structures. Therefore, understanding the 3D folding of chromosomes allows one to improve DNA technologies in order to enable better and more stable expression of desired genes.
Thanks for posting this, it helps clarify the scales involved. One question I haven't been able to find an answer to: Is it known whether the larger chromatin structures are anchored in place by actin filaments?
Excellent video! Clear/straightforward/concise visualization of these different levels of organization. Beautifully done ...thank you for sharing! One thing I didn't understand though, (if anybody can enlighten this layman), ...the highest level noted, "chromosone territory", is said to correspond to entire chromosones, but the visual shows what I presume are those seperate entire chromosones, (represented as different colors), as amorphus blobs smushed against each other. Why do we not see the typical seperate "X" shapes of each seperate chromosone commonly seen under a microscope? Am I misinterpreting something?
Very good question! The X shapes are a special, highly condensed state of chromosomes which is only present as the cells are diving, in the process known as mitosis. This "X"' state is optimum for neatly segregating chromosomes into daughter cells without mistakes, but it is so condensed that it is incompatible with other functions such as transcription into RNA or duplication of the DNA that is required before the cells can divide. During the remaining time of the cell life outside mitosis, when the cell is functioning, producing proteins and metabolites that maintain our body function, chromosomes partially decondense and they are no longer visible with this X shape but take the form of the pseudo globular chromosome territories depicted in the video. You can take a look at the education video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-gbSIBhFwQ4s.html. The first 30 seconds show folding into nucleosomes and are correct. From 30 seconds to 1minute 15 seconds they model the folding of nucleosomes into chromatin fibers, and this is the part that needed to be corrected, which we did with our video. After 1 minute 15 seconds you see the X-shaped chromosomes in mitosis and then you see how they decondense under the microscope in a time-lapse video of a cell mitosis. Hope this helps!
@@cavallilabvideos8738 Thank you ...extremely helpful! Your explanation makes it all very clear, and I see that "X" state is indeed noted as very temporary/mitosis only in the other video you noted. Fascinating! These 3d visualizations are such an incredibly wonderful/powerful clarification tool!! So many aspects/details/contextual elements come to light that otherwise would be hazy or out of mind. (Though I suppose there are also numerous secondary aspects that must still be speculative in such inherently comprehensive/literal/thorough/detailed representations, (such as the particular motions for example perhaps). Regardless ...much better to have reasonable speculative placeholder secondary aspects to fill out a full picture.) Really appreciate what you do and share!!
Dear Nori, you will find in the discussion detailed information and further readings on many data that converge toward the interpretation that is showed in the video. Nevertheless, putting together experimental evidence on subjects of sizes that are over a million fold smaller than a centimeter (1-10 nanometer) is always a difficult and uncertain challenge and probably we will have to change several points as the knowledge progresses in the coming years. Stay tuned ...
The genes for the heavy and light chains of immunoglobulin are in chromosome 2, 14 and 22. I was wondering if these chromosomes are neighboring each other in the nucleus and specifically in the b-cell. In this nice animation I see that the chromosomes are colored. Is there a map between the colors and the chromosomes?
Great question and I can not answer but the 3D organization of the B-cell genome was studied in this paper: www.nature.com/articles/s41467-020-20849-y. You might contact the corresponding authors José Martine-Subero at imartins@clinic.cat or Marc Marti-Renom @ martirenom@cnag.crg.eu for more infos!
Yes, H3K27Acetylation will prevent PRC2 to deposit H3K27 methylation by direct competition and so H3K27Ac blocks silencing. Furthermore, H3K36 di- or trimethylation inhibits PRC2. see article DOI: 10.7554/eLife.61964 for an explanation of the mechanism.
It is a company called Arkitek Scientific, www.arkitek.com/ ! Excellent people, we had lots of discussions with them in order to get the concepts straight and then to refine them in order to be precise and improve the rendering, they were responsive and efficient throughout the process !
India education better than France education because India ancient time Sushrut teaching the world how to teach anybody but your explanation is very nice
Yes, nucleosome clutches were first observed by Maria Aurelia Ricci and colleagues in 2015, using the incorporation of a fluorescent histone into the chromatin fiber and its observation with Stochastic Optical Reconstruction Microscopy (STORM, see link 1- below), an advanced fluorescence microsopy method that provides extremely high spatial resolution. These small nucleosome aggregates were confirmed by Ou and colleagues, using ChromEMT, which combines "multitilt electron microscopy tomography" with a labeling method to selectively enhance the DNA contrast (again, advanced microscopy methodology, see link 2- below). These nucleosome aggregates represent a disordered 5- to 24-nm-diameter curvilinear chain that can be further packed inside interphase nuclei: 1- www.cell.com/action/showPdf?p... 2- doi.org/10.1126/science.aag0025
Very interesting model of chromosome organization. The concept of nucleosome clutches of variable number of them coming together and then organizing into chromatiin nano domains (CNDs) is a new thought which further highlights dynamicity of chromatin in interphase. A good model to work upon.
