Question

TAC and JAX are two different strain of mice. Both were injected with melanoma (cancer) cells and the growth of tumors in the animals was monitored for several days. With respect to the following figure: What are the results? . 1500 -a-TAC ㅎ. JAX What do the results tell you about the two mouse strains? . 500 7 10 13 16 20 22 Day post injection In another experiment, TAC mice were co-housed with JAX mice for three weeks. During the co-housing, the mice are exposed to and acquire bacteria from the feces that they may chew on or consume, leading to changes in the composition of the bacterial communities in their guts. The mice were then injected with melanoma cells and the growth of tumors in the animals was monitored for several days. With respect to the following figure: 1TAC JAX What are the results? 1000 NS What might these results mean? 710 1316 2022 Day post injecton How might these results alter our understanding of what constitutes a functioning organ?

Answer 1

Answer:

(a) (i) JAX and TAC mice exhibited significant differences in melanoma growth rate, with tumors growing more aggressively in TAC mice.

(ii) This difference was immune-mediated: Tumor-specific T cell responses and intratumoral CD8+ T cell accumulation were significantly higher in JAX compared to TAC mice.

(b) (i)  Cohousing ablated the differences in tumor growth and immune responses between the two mouse populations, arguing for an environmental influence.

(ii) TAC mice appeared to acquire the JAX phenotype upon cohousing, suggesting that JAX mice may be colonized by commensal microbes that dominantly facilitate antitumor immunity.