Table 3.
Diet effects on crossover frequency in C57BL/6 male mice: analyses per spermatocyte and per bivalent
| (A) B6 spermatocytes: | Maintenance diet | Breeding diet |
|---|---|---|
| MLH1 foci | 23.50 ± 2.17a | 24.24 ± 2.31b |
| SC length (μm) | 169.0 ± 21.2 | 164.6 ± 17.9 |
| (B) Number and type of bivalents: | ||
| E0 | 19 (0.5%) | 16 (0.5%) |
| E1 | 2808 (75.4%) | 2417 (71.8%) |
| E2 | 895 (24.0%) | 927 (27.5%) |
| E3 | 2 (0.1%) | 5 (0.1%) |
(A) After analyzing an independent group of B6 mice, a significant increase in MLH1 foci count per spermatocyte was again observed in animals fed with breeding diet respect to those kept in maintenance diet (ab, t-student test, P = 0.001), while no significant differences in SC length were detected (P = 0.20, Mann–Whitney U test). Data are the result of the analysis of 196 spermatocytes in the maintenance group and 177 in the breeding group. (B) When bivalents were classified according to the number of crossovers (E0–E3), a significant change was also observed (P = 0.004, χ2 test). This change was mainly due to an increase of E2 bivalents at the expense of E1 in the breeding group, respect to the maintenance group.