Preserving a high degree of genome integrity and stability in germ cells is of utmost importance for reproduction and species propagation. However, the regulatory mechanisms of maintaining genome stability in the developing primordial germ cells (PGCs), in which rapid proliferation is coupled with global hypertranscription, remain largely unknown. Here, we find that mouse PGCs encounter a constitutively high frequency of transcription–replication conflicts (TRCs), which lead to R-loop accumulation and impose endogenous replication stress on PGCs. We further demonstrate that the Fanconi anemia (FA) pathway is activated by TRCs and has a central role in the coordination between replication and transcription in the rapidly proliferating PGCs, as disabling the FA pathway leads to TRC and R-loop accumulation, replication fork destabilization, increased DNA damage, dramatic loss of mitotically dividing mouse PGCs, and consequent sterility of both sexes. Overall, our findings uncover the unique source and resolving mechanism of endogenous replication stress during PGC proliferation, provide a biological explanation for reproductive defects in individuals with FA, and improve our understanding of the monitoring strategies for genome stability during germ cell development.

We describe automated nucleic acid (NA) isolation from diverse sample types using MagMAX kits (Ambion, Inc.) on KingFisher Magnetic Particle Processors (Thermo Scientific). The MagMAX-96 Blood RNA Isolation Kit is designed for total RNA isolation from whole blood from several species, without white blood cell fractionation, in about 45 min (including genomic DNA removal). The MagMAX-96 Total RNA Isolation Kit is designed for total RNA isolation from up to 2 × 10 6 cultured cells and up to 10-mg tissue. The isolated total RNA is highly intact and pure, ready to use in downstream applications such as microarray analysis or real-time reverse transcription (RT)-PCR for gene expression profiling or pathogen detection. The MagMAX-96 Viral RNA Isolation Kit is designed for viral RNA and DNA isolation from cell free or nearly cell-free samples such as swabs, serum, and plasma; it takes about 15 min. Total NA of high quality and purity is recovered at >75% efficiency, providing high sensitivity for pathogen detection by real-time RT-PCR. Unlike automated liquid handling systems that move reagents into and out of a single well of a multiwell plate to perform the different steps of an RNA isolation procedure, the KingFisher Magnetic Particle Processors use permanent magnetic rods to collect magnetic beads from solution and release them into another well containing reagent for the subsequent step of the procedure. The effectiveness of bead collection and transfer lead to superior washing and elution efficiency, as well as rapid processing. It is a very effective strategy for automation of magnetic-bead-based NA isolation kits. (JALA 2007; 12:195–201)

884Update of variants iden fi ed in the pancrea c β-cell K ATP channel genes KCNJ11 and ABCC8 in individuals with congenital hyperinsulinism and diabetes 983 Fundamental role of BMP15 in human ovarian folliculogenesis revealed by null and missense muta ons associated with primary ovarian insuffi ciency Raff aella Rosse , Ilaria Ferrari , Ilaria Beste , Silvia Moleri , Francesco Branca , Luisa Petrone , Palma Finelli and Luca Persani 998 Func onal characteriza on of the fi rst missense variant in CEP78 , a founder allele associated with cone-rod dystrophy, hearing loss, and reduced male fer lity 1025 Cri cal assessment of secondary fi ndings in genes linked to primary arrhythmia syndromes Volume 41 , Number 5 was mailed the week of April 06, 2020 Front Cover: The cover image is based on the Research Ar cle FANCL gene muta ons in premature ovarian insuffi ciency by Yajuan Yang et al., h ps://doi.

FANCI is an essential component of Fanconi anemia pathway, which is responsible for the repair of DNA interstrand cross-links (ICLs). As an evolutionarily related partner of FANCD2, FANCI functions together with FANCD2 downstream of FA core complex. Currently, growing evidences showed that the essential role of FA pathway in male fertility. However, the underlying mechanisms for FANCI in regulating spermatogenesis remain unclear. In the present study, we found that the male Fanci−/− mice were sterile and exhibited abnormal spermatogenesis, including massive germ cell apoptosis in seminiferous tubules and dramatically decreased number of sperms in epididymis. Besides, FANCI deletion impaired maintenance of undifferentiated spermatogonia. Further investigation indicated that FANCI was essential for FANCD2 foci formation and regulated H3K4 and H3K9 methylation on meiotic sex chromosomes. These findings elucidate the role and mechanism of FANCI during spermatogenesis in mice and provide new insights into the etiology and molecular basis of nonobstructive azoospermia.

No abstract