Molecular support for high paracellular absorption in the intestine of flying mammals 

ENRIQUE CAVIEDES-VIDAL; BRUN A; FERNÁNDEZ MARINONE, G.; CLAUDIA GATICA-SOSA; EDWIN R. PRICE; AYELEN AMWEG; HUGO ORTEGA; KARASOV WH

San Diego

Congreso; Experimental Biology Annual Meeting; 2014

Federation of American Societies for Experimental Biology

Flying mammals absorb water­soluble nutrients (e.g. glucose) at the intestine mainly by the paracellular route [across tight junctions (TJ) between adjacententerocytes], while non­flying mammals mainly rely on the transcellular route (across cell membrane using transporter proteins). We predicted thatinsectivorous bats Tadarida brasiliensis, compared to Mus musculus, would show enhanced expression of CLDN­2 (CLDN=claudin) and OCLN (occludin)TJ proteins, which have been described as responsible for the permeability of polar water­soluble solutes. We assessed the level and spatial distribution ofCLDN­2, ­3, ­5, ZO­1 and OCLN by immunohistochemistry along the villus axis in the proximal intestine. Immuno­specificity of the antibodies was checkedby western blot. No differences were found for CLDN­3 and ZO­1 between species. We confirmed low expression of CLDN­2 in mice (Holmes et al. 2006,Gene Expr Patterns 6: 581­8; no signal detected in our preparations), but in bats the villus tips exhibited CLDN­2. OCLN was expressed along the entirevillus axis but with a stronger signal for the bat than for mice, giving additional support to our prediction. A third difference was that CLDN­5 was stronglyexpressed along the villus in bats, whereas in mice its presence was not detected. Findings suggest potential molecular mechanism(s) underlying theobserved higher paracellular absorption in bats compared to mice.