I'm making a cytogenetic characterization of chromosomes in meiosis, specifically during prophase I and as you can see in the picture, this cell must be in pachytene forming a synaptonemal complex but the chromosomes circled are already separating because chiasma can be seen. I got a lot of this results where some chromosomes are early or delayed and I wanted to know if it is of natural occurrence, is part of the treatment or product of some mutation.
I worked with a male Mus musculus, colchicine 0.1%, Carnoy, sodium citrate and OLA 2%.
Any help would be appreciated. Thanks in advance
so you can get asynapsis due to problems with synaptonemal complex formation, cohseins, or from treatments with certain chemicals. However to get a real understanding you will probably want to do a prep that can let you look at more spread chromosomes. i have attached a publication where you can stain for SC with anti-scp3 on spread pachytene cells and get detailed analysis of asynapsis events.
Article Altered Cohesin Gene Dosage Affects Mammalian Meiotic Chromo...
Hello , I think that checkpoint controls can delay meiotic progression to allow defects or errors in these processes to be repaired or corrected. For example mouse spermatocytes possess quality control checkpoints that eliminate cells with persistent irreparable defects in chromosome synapsis or recombination, and as you know that during meiosis, recombination, synapsis, chromosome segregation and gene expression are co-ordinately regulated to ensure successful execution of cell division.
Hi Anny
I agree with Nichole that you should try to get better spreads of your chromosomes. On the other hand, I do not know what is the circled structure in your picture. However, for the chromosomes to start to separate the spindle must have formed, and I do not see any trace of it in your picture.
Some time ago, we inferred asynchrony among chromosomes related to their size, but I am not sure this would apply to your data
https://www.researchgate.net/publication/237188064_Independent_arrangement_of_bivalents_and_or_quadrivalents_in_linear_meiotic_metaphase_plates_of_rye
Pablo
Article Independent arrangement of bivalents and (or) quadrivalents ...
I guess this reported event must have been consistent before it could be seen as a feature of the study case. Nature has ways of enforcing order in cytological events, which include progression of karykinetic processes. There is need to observe several more chromosome spreads to confirm that the observation is actually consistent with the study sample. There is also need to extend the investigation to a large population to ensure that it is not an uncommon case. If it persists, then it could be suspected as a natural event, but if it does not persist, it could then be passed for a special or conditional case. The quality of chromosome slide may also cause what seems like uneven progression of the cell division process.
Thank you so much for your responses, all have been really useful. For those interested, it appears that the event was product of the chemicals and the concentration of them that I used in my procedure, when I changed the times and concentration I didn't see this problem.
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