Non-homogeneous marking of distal colonic mucosa using Dolichos biflorus lectin

Bone marrow cells in murine colitis: multi-signal analysis confirms pericryptal myofibroblast engraftment without epithelial involvement

Background

The contribution of bone marrow-derived cells to epithelial tissues in the inflamed gut remains controversial. Recent reports have suggested that cell fusion between bone marrow-derived cells and the intestinal epithelium takes place in inflammatory conditions.

Methods

In attempts to confirm this, we have undertaken gender mis-matched bone marrow (BM) transplants from male Swiss Webster (SWR) mice to B and T cell-deficient female Rag2 KO mice which, 4 weeks later, were given 5% dextran sodium sulphate in drinking water to induce acute colitis. A further BM-treated group of animals with a graft versus host-like condition was also studied. We developed a new method to combine up to three brightfield or fluorescent lectin- or immuno-histochemical signals with fluorescent in situ hybridisation for the Y and X chromosomes to enable us unequivocally to identify BM-derived male cells which presented as different cell types in the gastrointestinal tract.

Principal Findings

In rolled preparations of whole intestines we scanned around 1.5 million crypts at many tissue levels. In no instance did we see a Y chromosome-positive cell in the epithelial compartment, which was not also CD45-positive. We saw no evidence of cell fusion, based on combined X and Y chromosome analysis. Levels of CD45-positive stromal and lymphoid cells and pericryptal myfibroblasts (positive for α-smooth muscle actin) increased with time up to a plateau, which resembled the level seen in untreated control grafted animals. We saw very few Y chromosome-positive endothelial cells in intestinal stromal vessels.

Conclusions

We conclude that whole BM transplantation does not result in intestinal epithelial engraftment in this model. Our new methods can usefully assist in multi-signal analyses of cell phenotypes following BM transplant and in models of chimaerism and regenerative medicine.

Mapping behavioural evolution onto brain evolution: the strategic roles of conserved organization in individuals and species

The pattern of individual variation in brain component structure in pigs, minks and laboratory mice is very similar to variation across species in the same components, at a reduced scale. This conserved pattern of allometric scaling resembles robotic architectures designed to be robust to changes in computing power and task demands, and may reflect the mechanism by which both growing and evolving brains defend basic sensory, motor and homeostatic functions at multiple scales. Conserved scaling rules also have implications for species-specific sensory and social communication systems, motor competencies and cognitive abilities. The role of relative changes in neuron number in the central nervous system in producing species-specific behaviour is thus highly constrained, while changes in the sensory and motor periphery, and in motivational and attentional systems increase in probability as the principal loci producing important changes in functional neuroanatomy between species. By their nature, these loci require renewed attention to development and life history in the initial organization and production of species-specific behavioural abilities.

Preliminary analysis of azoxymethane-induced colon tumorigenesis in mouse aggregation chimeras

Inbred mice exhibit differential susceptibility to colon carcinogens. The following study addresses the possibility that differences are intrinsic to colonic mucosa (cell autonomous) or are mediated by extracolonic systemic factors (e.g. liver activation of carcinogens). Our approach was to construct mouse aggregation chimeras, mice whose tissues are a mosaic of cells derived from two parental genotypes, from a susceptible (SWR) and a resistant (DBA/2) strain. Forty-five embryo aggregations yielded 11 viable pups, four of which were chimeric by coat color. Six-week-old SWR<-->BA/2 chimeras were injected i.p. with azoxymethane (AOM) once a week for 8 weeks (5 and 7.5 mg/kg body wt for 2 weeks followed by 10 mg/kg for 6 weeks) and tumor incidence in distal colon was evaluated 15 weeks after the last injection. Additional groups of parental mice received the same treatment. In the parental SWR treatment group, 1.7 +/- 0.82 tumors/colon were found. No tumors were observed in AOM-treated DBA/2 mice. In SWR<-->DBA/2 chimeras exposed to AOM, 2.8 +/- 2.1 tumors/colon were found. Tumor lineage was examined in paraffin sections stained with Dolichos biflorus agglutinin-peroxidase, a cell surface specific marker that stains intestinal endothelial cells of SWR and epithelial cells of DBA/2. Cellular lineage of tumors was further evaluated by microsatellite analysis of DNA isolated by microdissection. There was no significant difference in tumor incidence between SWR parental and chimera treatment groups. Histochemical analysis of tumor tissue in chimeras suggested that most tumors were derived from SWR. However, subsequent genetic analysis of tumors indicated mixed parental composition. These preliminary studies suggest that DBA/2 resistance mechanisms are not sufficient to protect adjacent SWR-derived epithelium from the tumorigenic effects of AOM.