Meeting Abstract
We previously documented varied changes in the colonic microbiomes of animals representing five classes of vertebrates (i.e., tilapia, toads, leopard geckos, quail, and mice) over the course of fasting. In the current study we tested the hypotheses that the extent of tissue reorganization in the fasted colon was correlated with the observed changes in the microbiome. Colon segments adjacent to those used for the genomic study were fixed in Carnoy’s solution, mounted on slides, and stained with hematoxylin and eosin. We used ImageJ software to quantify cross-sectional and mucosal surface areas as well as thicknesses of mucosa, submucosa, and tunica muscularis. We found no fasting-induced differences in the morphology of colons of the mice (3days), quail (7days), or geckos (28 days). The toads that exhibited a general increase in phylogenetic diversity of their microbiome also exhibited reduced mucosal circumference at 14 and 21 days. The tilapia that increased their phylogenic diversity also exhibited a thickened tunica muscularis in 21 days, but this change is unlikely to explain the dramatic changes in their microbiome that we documented. Given that the mice and quail exhibited fasting-induced increases and reductions, respectively, in their microbial diversity but did not exhibit detectable changes in colon morphology, we conclude that structural reorganization is not the primary factor shaping changes in microbial diversity within the fasted colon.
