Following this interesting question

Hello Noé. How are you doing today?

Hum, firstly scales are difficult to obtain high quantity of genomic DNA. The quantity of DNA you can obtain from one sample depends of how much cells are in there. Scales have few quantities of cells to get large amount of DNA. Also, the keratin present in the scales impar the efficiency of extraction process if you don’t use something capable to degrade it.

You mentioned that using extraction kit you get less than 10ng/ul in 75ul elution volume. I suggest to eluate your sample in a lower volume, 10 to 20ul to concentrate your DNA. However, as the DNA seems degraded on agarose gel, probably there are something wrong during the extraction process.

So, my suggestions are the following. Try to remove the most keratin part of scale and use only the part connected to the body to extract DNA. Maybe this can improve the extraction of the kit. Alternatively, you can use a saline extraction protocol with or without phenol-chloroform. You will find more detailed in this paper doi:10.1101/pdb.prot4455.

Well, my best regards Noé and good luck in your research.

You can read this link ( https://link.springer.com/article/10.1007%2Fs10126-001-0010-9 ) maybe it can help.

Rapid Isolation of DNA from Fresh and Preserved Fish Scales for Polymerase Chain Reaction ...

Thank you both for your answers, I will look into it !

Best regards,

Noé