Pappa2 deletion in mice affects male but not female fertility

Table 1 Reproductive traits of mice homozygous for Pappa2 disruption (Pappa2 ^KO/KO) or homozygous for the intact allele (Pappa2 ^fl/fl)

	Females			Males
	Pappa2 ^fl/fl	Pappa2 ^KO/KO	P-value^a	Pappa2 ^fl/fl	Pappa2 ^KO/KO	P-value^a
N	15	17		6	10
Mass at pairing (g)	23.5 ± 0.5	20.7 ± 0.4	0.0001	30.5 ± 0.7	24.6 ± 0.5	0.0001
Age at pairing (weeks)	19.5 ± 0.4	19.4 ± 0.4	0.80	19.5 ± 0.8	19.4 ± 0.6	0.97
Days between pairing and birth of first litter	27.0 ± 2.0	24.0 ± 1.9	0.28	25.3 ± 2.2	22.3 ± 1.7	0.28
Days between births of first and second litters	30.6 ± 1.1	26.7 ± 1.1	0.11	23.1 ± 1.1	38.8 ± 1.1	0.0001
Proportion of matings that produced second litter within 35 days of birth of first litter^b	8/14^c = 57.14 %	15/17 = 88.24 %	0.10	6/6 = 100 %	2/10 = 20 %	0.0070
Size of first litter at birth	8.1 ± 0.6	7.8 ± 0.6	0.75	8.8 ± 0.7	8.4 ± 0.6	0.65
Size of first litter at wean	7.5 ± 0.6	7.3 ± 0.6	0.85	8.6 ± 0.8	8.2 ± 0.6	0.69
Size of second litter at birth	7.6 ± 0.6	8.1 ± 0.5	0.50	6.3 ± 0.9	8.2 ± 1.0	0.20
Size of second litter at wean	6.9 ± 0.6	7.4 ± 0.5	0.54	5.8 ± 0.8	6.0 ± 0.9	0.90

^aFor most traits, values are least squares means ± standard error from a general linear model including the effect of genotype (GLM procedure; SAS, ver 9.3). The number of days between the births of the first and second litters was analysed using failure time analysis with a log-logistic distribution, with females that did not produce a second litter included as right-censored observations (LIFEREG procedure), and the proportion of matings that produced a second litter was analysed using Fisher’s Exact Test (FREQ procedure, chisq option). Analyses with nonparametric tests (Wilcoxon, Kruskal-Wallis; NPAR1WAY procedure) yielded qualitatively similar results
^bIn the first set of pairs, males were removed from females two weeks after the first litter was born, and therefore the females could only have given birth to a second litter within 35 days of the birth of the first litter. In contrast, pairs in the second set of matings were left together until the birth of the second litter
^cOne female died while delivering first litter and so was not included in this analysis

ISSN: 1477-7827