Both studies focus on differences in the expression of the housekeeping gene under two different conditions, normal and cancer/diseased tissue, and indicate that using two or more housekeeping genes allows for the detection of any systematic bias that may arise.
Only minor differences in the expression of this housekeeping gene were observed between the different tissues (data not shown), suggesting that 18S rRNA can be used for normalization.
The genetic distance between two strains can be quantitatively estimated as allelic differences in the nucleotide sequences of housekeeping or virulent genes among bacterial strains [ 8].
It involves detecting allelic differences in the sequences of various housekeeping genes [ 20– 22] and can also been extended to include virulence genes [ 23].
Ct values were standardised against HMBS (PBGD), the least variable housekeeping gene, to avoid errors due to differences in efficiency between the housekeeping and test genes, which were present from cycle 27 to 35 in most cases.
All strains had homologous type 11 sequences without any nucleotide differences in seven housekeeping genes.
First of all, the two sets of results are not directly object of comparison, for the reason that different methodological approaches were used (cellular separation vs. total blood, differences in housekeeping genes, different algorithms and statistical tools applied to results from RT-PCR assays...)...
However, for many experimental applications, we must make the difference between the housekeeping genes which are constantly expressed in all the tissues and the ubiquitous genes.
To test if there is statistically significant difference in R between the housekeeping genes in State 1 and State 2: Randomly sample 192 housekeeping genes and evaluate R Find another R using the rest of the housekeeping genes Repeat the procedure 1000 times and count the number of procedures in which the R difference is larger than the observed R difference.
Furthermore, the differences in the chromatin features between specific genes and housekeeping genes indicate the involvement of chromatin organisation in the control of gene expression [ 6].
