1. Epigenetic inheritance in the mouse
Irmgard Roemer, Wolf Reik, Wendy Dean, Joachim Klose 
Current Biology 
Volume 7, Issue 4, Pages (April 1997)
DOI: /S (06)

2. Figure 1
Sections from two-dimensional electrophoresis patterns [37] of mouse tissue proteins. Liver, heart (data not shown) and brain protein extracts from adult animals were separated by high resolution two-dimensional electrophoresis [37] and patterns were compared for experimental and control groups. In liver, ∼ spots were examined, in heart muscle 4 000, and in brain (counted by laser densitometry and computer analysis). (a–c) Brain proteins: the arrowed spot is present in natural hybrids (C57BL/6×DBA/2) (a), but completely absent in NC hybrids (BDB) (b) and in NC hybrid offspring (c). Sequencing of peptides from this brain protein (LIRPAES, VYRLDFIQQQ, VMYFLITFGEGVEP, ASVVFNQL; single-letter amino-acid code) identified it as OMP. (d–i) Liver proteins from (d–f) female and (g–i) male mice: the arrowed spots were previously identified by partial sequencing as MUPs, and are present in natural hybrids (C57BL/6×DBA/2) (d,g), but substantially reduced in NC hybrids (BDB) (e,h) and in NC hybrid offspring (f,i). In addition to OMP and MUP shown in this figure, there were 11 spots in liver, 5 spots in heart and 12 spots in brain that showed quantitative differences between experimental and control groups.
Current Biology 1997 7, DOI: ( /S (06) )

3. Figure 2
Methylation patterns of Mup genes obtained from B1 mice of the backcrosses B6×DBD and B6×BDB, from an NC hybrid male (BDB), and from controls. Males and females were investigated. Note that there are sex-specific differences in methylation of some Mup genes [4], which is why we show both male and female methylation patterns. DNA samples from adult liver (10 μg) were digested with BamHI and MspI or the methylation-sensitive restriction enzyme HpaII, as recommended by the supplier (NBL). Digested samples were electrophoresed through 0.8–1% agarose gels and blots were hybridized and washed at high stringency [38]. The inserts of the probe BS655 [39] were digoxigenin-labelled by random priming [40]. The detection of digoxigenin-labelled nucleic acids by enzyme immunoassay with luminescence on nylon membranes was performed following the standard procedure described in the manual of the DIG luminescence detection kit (Boehringer-Mannheim, Germany) with some modifications: the detection procedure was modified by doubling the hybridization volume and the number of blocking, washing and incubation steps. The organization of group 1 Mup genes, restriction enzyme sites and the probe used have been described elsewhere [4]. BamHI–MspI fragments diagnostic for the Mup genes BS5, CL8, BL1 and CL11 are indicated on the right, and DNA marker sizes on the left. Abbreviations: DNAm, DNA methylation; N, normal; I, increased. The mouse types are explained in the legend to Table 1. All gels were scanned and methylation indices were calculated from the ratio of uncut (methylated) fragment to cut (unmethylated) fragment. The indices were: CL11 (3.8kb → 2.6kb); BL1 (3.8kb → 3.0kb); BS5, CL8 (5.6kb → 4.4kb). For each gel, ratios of these indices were calculated between NC hybrid animals and controls. Because BS5, CL8 and BL1 show sex-specific methylation differences [4], the CL11 index was used to define ‘normal’ and ‘increased’ methylation. The control group had a mean of 1 and a maximum of 1.5. Animals in the experimental group were described as having ‘normal’ methylation if they fell into this range, and as having ‘increased’ methylation starting from an index of 2 and ranging up to 10.
Current Biology 1997 7, DOI: ( /S (06) )

4. Figure 3
Growth deficiency of NC hybrid offspring. The histograms show body weights (mean ± standard deviation) of B1 male mice (a) and B1 female mice (b) on postnatal day 35 of the B6×DBD and B6×BDB backcross (Experimental), and B6×BBD controls (Control); and of B1 embryos and B1 controls on embryonic days 14 (c) and 15 (d). The differences in weight in (a,b) were significant by Welchtest (p <0.01). The difference between experimental and control B1 mice continued to be significant (p<0.05) on days 40 and 60 in the male group, but not in the female group. Variances pooled between male and female groups were significantly higher in the experimental than the control group (p<0.05 on day 35), suggesting that the differences between the experimental and control groups could be due to the presence of normal-sized and significantly smaller animals in the former group. A bimodal distribution, however, could not be fitted to the data. (c,d) The difference in body weight between the experimental and control B1 groups apparently arises between embryonic days 14 and 15 (variance analysis p<0.001).
Current Biology 1997 7, DOI: ( /S (06) )