Jeannie Lee (Harvard) 1 - X Chromosome Inactivation: Making and Breaking the Silence

[@rogerparker3422]

A super lecture, very well presented. Thanks Jeannie Lee and iBiology!

[@Viz_lifelore]

expected to learn more on Mary Lyon's experiments that led her to this groundbreaking conclusion, someone please let me know any source to learn about that!

[@000Krim]

This channel is amazing

[@aaquib608]

Absolutely

[@sagarak999]

What an amazing lecture!!

[@danchokonstantinov6735]

Great lecture . I always maintained that junk DNA is a false statement of incomplete scientific knowledge. Of interest is if increase in gene expression requires a fine tuning expression , in other words is overexpression of a particular gene beneficial and chronologically determinant.

[@aintnothingbutchickenwing]

With the references too

[@hannahmich7342]

I find this lecture really informing. I have one from of intersex. During gestation my germ cells failed to fully reach the gonads. Thus one gonad remained as a fetal gonad, ovotestis and an attached germ cell teratoma. Depending on how you define it. My other gonad did develop as a testis but remain small and immature. If that were not enough I have a number of germ cell teratoma found in various areas of my abdomen. Two were removed when I was ten years old and several others were found when I was an adult. These teratoma were 10 cm and 17.5 cm when surgically remove. The 10 cm one happened to also be malignant. I tend to be asexual but also see myself as being transgender.

[@hannahmich7342]

@Ismael barrera Interesting! I’ll have to digest this information and do more study

[@crynotable]

Very nice

[@Dirajmk]

thank you

[@ButteredFlied]

My name is Jeannie

[@brentweissert6524]

fascinatiing. When you say that this is something that all mammals do, am i correct in assuming that this does not happen in non mammals, for example, reptiles? if so, why?

[@xyz9250]

If you reactive the inactive X, will it also inactive the previously active X? otherwise wouldn’t it lead imbalance and cause other problems?

[@rawaaa3359]

Hello, how could we say in the X-linked inheritance that there is a carrier or pure form if the second x chromosome is inactivated anyway and how the presence of one x chromosome would affect if always the only one X is activated.

[@cerberaodollam]

Hmmmm. If inactivation turns us basically into Turners, why do Turners have a recognizable condition? Or they turn off that one by mistake in some cells?

[@bearpancakes]

Because there’s control mechanisms, the inactivated X is not turned useless, it is still used to control/balance the active X

[@priyankajaikumar]

severe phenotype character are seen in turners due to deficiency in escape genes from silencing.

[@OxMxFxG123]

Not all genes are silenced on the inactive X. A bunch of genes escape inactivation.

[@thomassahotra7423]

It’s not all inactive still 10% xicst rna but which one gets inactived israndom and it happens in mammals for dosage compensation

[@thomassahotra7423]

Does anyone know which x passes down to germ cell during meiosis in females and how this process is reversed

[@nailamusa5943]

Hello mam My question is, the inactivation of x chromosome have any effect on autosomal genes?

[@madhurakamat1656]

Then how are females safe from X linked or sexlinked diseases if this phenomenon occurs? What happens then?

[@bearpancakes]

Females can still be affected by X linked diseases but it’s a little more tricky than it seems. If it’s a dominant condition and the affected X is active, the disease will be present; if it’s a recessive condition (only presents in homozygous) then the other unaffected X can compensate for it, and if it’s the unaffected X that’s active the disease will not be present.

[@robertogonzalez6083]

@@bearpancakes so in a recessive condition if the unaffected X is silenced then the disease will be present, yea?

[@GauravSharma00]

I had the same question, particularly with regard to color-blindness, which, as I understand it, is a X-linked recessive condition. The best explanation that I could come up with in view of what was presented in this lecture, was in terms of the random “mosaic” of activation in the cells of a female. So consider a female having two X-chromosomes, one of which carries the allele for colorblindness and the other carries the normal allele. Because the cells in the female will be a “mosaic” composed of cells in which either one of the X-chromosomes is inactive, about half the cells will have the X-chromosome with the normal allele as the active one, staving off color-blindness (and similarly other X-chromsome linked recessive conditions). Fascinating lecture, but as in much of Biology, generated more questions than it answered!

[@cerberaodollam]

"there are no supernumerary Xes" - with some excepions ;)

[@madhurakamat1656]

What about intersex?

[@richardwu9013]

Which definition are you talking about?

[@iam_google_mai3167]

That why you not advanced in genitc and u will never be until understanding the polarities of these jens

[@iam_google_mai3167]

First it's not y x. It's h and small x for what we gain from eating that is important to live your so wrong and I proud to tell