why no 28S RNA?

Narayanan Karthikeyan karthi at CCVAX.SINICA.EDU.TW
Wed Dec 23 11:48:28 EST 1998

> Dear netters,
> I have made total RNAs from earthworm for many many times, 
> but only got 18S band on agarose gel, no 28S band at all. I 
> could get 28S and 18S RNAs with other materials such as fish 
> egges and chiken liver. It doesn't like being digested by 
> RNase, because the 18S band was very sharp and small band 
> down the gel was not much . I have been trying with many 
> protocals including Promega's total RNA isolation system 
> using Guanidine thiocyanate, PerSeptive's purification kit 
> using Proteinase K and the method combining phenol 
> extraction and LiCl precipitaion. What ever a protocal I 
> used the results were almost the same, e.g. no 28S RNA. I 
> have got tired, it seems no hope for getting 28S RNA with 
> earthworm. I really need help. Why is that? Any suggestions, 
> ideas and hints will be appreiciated. 
> Thanks in advance!
> Tianyu
> E-mail:jing at nic.hbu.edu.cn

I also wondered the same when I was working with Drosophila system. I
used to extract RNAs from Drosophila embryos and cell lines and found to
have only one band around 18S. I have no idea why it is like that. But
all my RNAs worked great for PCR and Northerns. So do not panic.
If anyone got the reason for this phenomenon please let us know.
Good luck

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