Hi Mariella! I tried writing you directly on ResearchGate but it wouldn't let me.<br /> Anyway, very interesting study. Congratulations. I had a few questions. First, when were samples taken for pH and tissue transcriptomics with respect to feeding? I might expect we could see not just differences across species but over time with respect to a feeding event within an individual.

Second, you seem to be characterizing the vampire stomach as an absorptive organ. But then I have to wonder, why does it exist? Why not simply reduce the stomach and let the blood meal go straight to the intestine? I mean, at least for water absoprtion, we showed that it was higher in the vampire intestine than the stomach. We suggested that the stomach served as a storage chamber for social food sharing (and gastric processing), but that while the bloodmeal was in this storage chamber, they might as well start doing some water absorption.

I would think along similar lines for what you are showing here. There's reduced or no acidity, reduced pepsin (so, reduced to no traditional gastric processing), and improved absorption of some nutrients. But then couldn't the bloodmeal just go straight to the intestine for all that absorption? It seems to me that the increased absorption is more incidental than the primary function of the vampire stomach. Or is there perhaps some feature of the vampire stomach absorption that trades off with absorption in the intestine?

Third: Any evidence of upregulated aquaporins in the intestine? You only noted upregulation in the stomach. I have been curious about this as a mechanism for intestinal water absorption across species with different dietary water loads.

Again, great study, Cheers- Eddy Price