C3Fe.B6-repro27 congenic mice (repro27, N10) display gender-specific sterility. Mice homozygous for the repro27 mutation contain a premature stop codon in exon 18 of the Golgi autoantigen, golgin subfamily a, 3 (Golga3) transcript. It was shown that disruption of Golga3 leads to defects in spermatogenesis. Indeed, increased germ cell apoptosis is observed as early as Day 12 in repro27 mutant mice, and the few germ cells that complete spermatogenesis yield abnormal and infertile sperm. Germ cell development appears normal up to the pachytene stage, but development could be disrupted earlier and go undetected until the pachytene stage. Alternatively, Golga3 may be required for normal Sertoli cell function, and mutated Golga3 disrupts the Sertoli cells' ability to support germ cell maturation. Currently, there is little information regarding Golga3 regulation during early germ cell development or in Sertoli cells. Here we characterize Golga3 mRNA levels in whole testes and Sertoli cells during early postnatal development in wild type and mutant and heterozygous repro27 mice. Because alternate splicing of the 5' end of Golga3 has been predicted, we amplified approximately 1.5 kb in this region to determine if splice variants are present in the testes. Testes cDNA samples were used from wild type C3HeB/FeJ mice on Days 4, 6, 8, and 14 (n = 2/day) and mutant repro27 mice on Days 6, 8, and 14 (n = 2/day). In wild type mice, two bands were detected on all days and sequencing data indicated that both bands are variants of Golga3. In mutant mice, Golga3 was either not detected or the presence of two bands was observed. To determine steady-state mRNA levels of Golga3 during early development, testes were collected from wild type animals on Day 4-5 (n = 3), 6 (n = 3), 7 (n = 3), 8 (n = 4), 9 (n = 4), and 14 (n = 4) and from heterozygous and mutant repro27 mice on Day 6 (heterozygous n = 3; mutant n = 4), 8 (heterozygous n = 4; mutant n = 5), 10 (heterozygous n = 4; mutant n = 3), and 14 (heterozygous n = 5; mutant n = 4). Relative to the Day 4-5 wild type samples, Golga3 levels increased over 10-fold in wild type mice on all sampling days with maximal induction of over 18-fold on Days 7 and 8. Heterozygous animals showed elevated levels of Golga3, but maximal induction was just over 6-fold on Day 8. Conversely, repro27 mutant mice showed very little induction of Golga3 mRNA and were under 2-fold during the sampling period. Since repro27 mutant mice exhibit a premature stop codon in Golga3 but also show decreased induction of Golga3 during early postnatal testes development, we hypothesized that the premature stop codon destabilizes the Golga3 transcript in mutant mice. To test this, Sertoli cells were isolated from 6-8 wild type, heterozygous, and mutant mice at 8-10 days of age. After 3 days of culture, Sertoli cells were treated either for 7.5 hours with DMSO (control) or 5 ug/mL Actinomycin D (n = 3 wells/treatment; 2 replicates) and Golga3 levels quantified. Contrary to results in the literature, Golga3 was detected in Sertoli cells. In wild type and heterozygous mice, Golga3 mRNA levels decreased approximately 1.5-fold after Actinomycin D treatment compared with nearly 3-fold in mutant mice. Results indicate that decreased Golga3 mRNA during early postnatal testes development causes infertility in repro27 mutant mice, and may be due to decreased transcript stability resulting from a premature stop codon. (poster)