Molecular Cytogenetics

[@kailashnathmishra9642]

Excellent explanation about FISH techniques

[@saravananramachandran5852]

Informative illustrative explanation on molecular cytogenetic analysis and FISH technique

[@ravindrapal577]

Nice presentation on molecular cytogenetic

[@hhaider5group]

Excellent description of Fluorescence in situ hybridization technique : thumbs-up !

[@atishkumargavit8554]

Good Informative video

[@Martin-uj4mi]

@Joseph Ross not sure if your explanation about deletion around 16:00 is correct. If you look at the visualization of the two chromosomes in question, you see they have the same size as of right now - meaning that if your theory was true, then the chromosome with the deletion would be way larger than the normal chromosome, if it *didnt* have the deletion

[@JosephRoss]

The tricky thing about cytogenetics is that several factors can distort the relative sizes of homologous chromosomes. Look at chromosome 3 in this human karyotype: www.genome.gov/genetics-glossary/Karyotype One homolog doesn't have an insertion or deletion relative to the other. It is for this exact reason that techniques like chromosome banding and FISH are critical for direct comparisons of homologs. The important aspect of molecular cytogenetics (including FISH) is that, like chromosome banding, it unambiguously identifies presence/absence of the FISH probe sequence on a chromosome. In this case, the deletion could be as few as hundreds of thousands of base pairs of DNA, which is too small a difference to detect visually, but if that sequence is missing from one homolog, FISH can detect that small difference.

[@ravindrapal577]

Very informative presentation

[@theresaveniegas1110]

Thank you, now everything makes sense. Didn’t understand this when it was being discussed with the professor

[@utpalendughosh934]

Good informative video..

[@RanjitSingh-gp3nc]

Nice presentation

[@rajkumarbiradar3587]

Beautiful explanation about Karyokynasis process followed by cytokinesis

[@anitakoeri2762]

Nice presentation sir

[@sheetalkalhapure4247]

Very good explanation with presentation.Very valuable....Thank u

[@niruraj7]

Very good and well explained lecture

[@1joannabullen]

Thank you so much for explaining this in a way that is accessible to students!

[@samraddhisinghmsc4233]

Beautiful please make a series on cytogenetics

[@darshanakorgaonkar8045]

Nice presentation. Thank you

[@yes_stretch_no_stress]

Thank you very much for this 🌟 very informative

[@ajitdighe7776]

Nice presentation Thank you

[@sailajavj6536]

Very informative lecture and well explained, Thank you sir.

[@avinashkudva8592]

Informative lecture. Thank you

[@hurriyahfajrissaadah8528]

aaaa this is amazing presentation, thank you mr :)

[@ijayita]

Excellent session.Thank you.

[@tekamerenwalling1519]

Excellent presentarion

[@prosenjitdawn5186]

Important concepts explained in simple way.

[@rajungdrr]

Very interesting session Thank you

[@dr.chaitanyajha7628]

Nice on FISH explanation

[@dr.sharadgiramkar942]

Nice explanation,...

[@samraddhisinghmsc4233]

How do we confirm between duplication and deletion in this like the case mentioned in deletion could also mean that there was duplication in the other one ( the one which we considered normal chromosome homologoue)

[@JosephRoss]

If I understand your question correctly, then the simplest answer is that the assumption is that a diploid individual has two copies (alleles) of each locus, and so in metaphase FISH we should see four signals, indication the positions of that locus on the four sister chromatids. If, for example, one pair of sister chromatids shows a FISH signal and the other doesn't, that would suggest a deletion. If one pair of sister chromatids has two sets of FISH signals, that would suggest that the locus has duplicated. Or, in another case, if a third pair of FISH signals exists on another chromosome, that would also suggest duplication.

[@samraddhisinghmsc4233]

@@JosephRoss thankyou for the explanation, although I wanted to ask that that what we are assuming as deletion in one of the homologoue could be duplication in the other homologoue ( the one which we thought to be normal one) so how do we confirm that

[@artiraval6161]

Nice explanation

[@saharalbanna2095]

that was amazing...thank u 2 much !keep on great work🙇

[@sharatkrsanasam2127]

Thanks you sir for your nice video session

[@guaroa1123]

Excelent!! amazing presentation.

[@jayasreedanduprolu1084]

very good information on aberrations

[@anshikasharaffkavya6484]

Very informative

[@MrPato2234]

could someone explain me something?? i have a doubt regarding the chromosomes and strands on dna identification. At 12:16, i think that the drawings for the explanations are only schematics. But, in the reality, the two sister chromatids that form one "chromosome" of the pair seen in a metaphasic spread (because at that stage the cell have a 4n "dna content"), each of them have a double dna strand, because of the way that the dna compacts. Right ?Could someone tell me if this is right?And by the way, if is right, this means that the probe binds to four sites on each "chromosome" of the pair ?Sorry for my english, i'm not native

[@JosephRoss]

To clarify: at 12:16, I've diagrammed two sister chromatids, each of which is a double-stranded DNA double-helix. Do note that, outside of mitosis and meiosis, a double-stranded DNA molecule would be called a chromosome. I think that reason you're having some confusion about ploidy (DNA copy number) and what I've drawn is that I'm only showing the metaphase pair of sister chromatids for one of the homologs of this chromosome. Put another way, for a diploid (2n) organism, at metaphase, you would see two "X"s (as I've just drawn one). For example, let's say I've drawn human chromosome 1. What I've diagrammed would be the two sister chromatids of the chromosome 1 that was inherited from the mother at birth. So, I've not also drawn the other version (homolog) of chromosome 1: the other pair of sister chromatids related to the chromosome 1 inheirted from the father at birth. So, yes at this stage in mitosis (or meiosis), the cell could temporarily be described as being 4n (although formally ploidy is defined at interphase before DNA replication, so a cytogeneticist would never refer to a metaphase nucleus as 4n), but I've only drawn two of the four double-helices for simplicity. Also, you're correct about probe binding: because at metaphase there are four homologous double-helices (for each of the maternal and paternal alleles there will be two double-helices), so you would observe four probe molecules binding in a high-resolution FISH experiment. For example, see: figshare.com/articles/_Visualization_by_FISH_on_mitotic_metaphase_chromosome_of_the_RNU2_locus_/821019 but notice that sometimes the two chromatids are close enough together that two probe signals merge into one.

[@mohd.shamsulhaque2965]

nice session

[@Hotchanna]

Great explanation! Well done! Thank you!

[@sharadbissa6210]

Revived knowledge.

[@ritus6468]

Very well explained. Thank you.

[@animalsciencewithdr.vijayz1101]

Well explained

[@yavuzyildirim6141]

quality content. but i have a question how single stranded dna from probe has more attraction to subject single stranded dna then its own pair how it manages to get in there quicker?

[@JosephRoss]

Mass action, essentially: molecular cytogeneticists apply a vast excess of probe compared to chromosomes. It only takes one molecule of probe to anneal to the chromosome of interest, so if we add 1,000,000 molecules of probes (just for example), then even if 999,999 probes re-anneal to their complementary DNA sequence, we still have one to anneal to the chromosome.

[@dr.yogeshmishra5740]

A very good explanation of chromosome abberation. Thanks

[@padmshreepatel824]

Tried well to explain Karyogram an how to construct it and other concepts of molecular cytogenetics.

[@danborri18]

Can we see deletion like you show in this apresentaion in the interphase ?

[@JosephRoss]

yes, you could. For a diploid cell, you would expect to see two FISH signals per locus; if a locus were deleted, then you would see none (or one, if the deletion only existed on one of the two homologs). The only difference in interphase is you cannot see the individual chromosomes clearly. I suggest searching the web for images of interphase FISH.

[@dr.heenamomin9476]

Excellent

[@akashmanoj9431]

This was amazing!

[@izzahflipsthetable7336]

Wait if every probe is for a specific chromosome, then does that mean every probe is the same for everyone? I mean, person A and person B can use the same probe, the probe being specific to chromosome 3 for example?

[@JosephRoss]

It depends on the specific probe (and most importantly its length). Generally speaking, any probe would be expected to hybridize to the same spot on the same chromosome in any person. However, if that chromosomal region is very different (at the DNA sequence level) between those two individuals, then it is possible the probe would hybridize to one person's chromosomes and not to the other's. There are also plenty of examples of copy number variation (CNV), where one person's chromosome might have multiple copies of the target site (so you'd observe multiple FISH signals), where another person's chromosome might not contain those extra copies of the sequence. As usual, the devil's in the details.

[@izzahflipsthetable7336]

@@JosephRoss Man thanks for the explanation appreciate it!

[@prosenjitdawn5186]

Ahhh nice talk. very informative.

[@kalyangiri5731]

Thank you.

[@jankithakker6232]

very nice

[@dr.nileshkumarpandya7595]

Thank you

[@drchandpasha]

Thanks

[@drchandpasha]

Thanks sir

[@rajkumarbiradar3587]

Beautiful images of chromosomal abberation

[@sanjeevupadhyay6996]

good

[@sueschaer2342]

amazing

[@Therealtalkpodcast1115]

pro tip : watch at 1.5x

[@prakashdabgar7170]

Thanks sir