ABSTRACT
Tight junctions are mainly formed by two types of proteins; claudins and
occludin, both of which are fundamental to maintain the integrity and barrier
function of the intestinal epithelium. This barrier function allows for the absorption
of nutrients, mainly by transcytosis; however, in birds, 90% of the substances
are absorbed by paracellular mechanisms. Despite this, claudins present in the
different parts of the intestinal tract of adult chickens are not known, much
less their functional role. This study aimed to determine the presence of mRNA
of claudins 1, 2, 3, 5, 10, 12, 16 and occludin, in the different regions of
the intestine (duodenum, jejunum, ileum, cecum, and rectum) in chickens (Gallus
gallus domesticus) through RT-PCR. To meet this goal, 7 weeks old roosters
destined for slaughter and chicken embryos of 16 days of incubation (positive
control) were used. For all the processed samples, amplicons of the expected
size were obtained; claudin 1 (662 pb), claudin 2 (162 pb), claudin 3 (185 pb),
claudin 5 (224 pb), claudin 10 (687 pb), claudin 12 (738 pb), claudin 16 (191
pb) and occludin (430 pb). To corroborate these findings, obtained amplicons
were sequenced and, subsequently, a basic alignment was performed on the NCBI,
obtaining a correlation of 100% with the original sequences in all analyzed
samples. To our knowledge, the present work represents the first written report
regarding the presence of mRNA of the main proteins involved in tight junction
formation throughout the intestinal tract of domestic chickens of 7 weeks of
age. These findings will allow elucidating the specific function of each of the
reported proteins in the process of paracellular absorption in chickens.