Recently, fertile spermatozoa and oocytes were generated from mouse induced pluripotent (iPS) cells using a combined in vitro and in vivo induction system. With regard to germ cell induction from human iPS cells, progress has been made particularly in the male germline, demonstrating in vitro generation of haploid, round spermatids. Although iPS-derived germ cells are expected to be developed t...

Nearly 2 m of DNA is so tightly packaged that it fits neatly within the nucleus of each cell of our body. As if this was not mind-blowing enough, the problem is intensified in the male germline, as the nucleus of a sperm cell is about 6 times smaller than that of a somatic cell. Sperm are highly specialized cells charged with the sole responsibility of delivering the paternal genome to offsprin...

Spermatogenesis is a key developmental process allowing for a formation of a mature male gamete. During its final phase, spermiogenesis, haploid round spermatids undergo cellular differentiation into spermatozoa, which involves extensive restructuring of cell morphology, DNA, and epigenome. Using mouse models with abrogated Y chromosome gene complements and Y-derived transgene we identified Y c...

The difference between transcriptional and translational activities of genes is one of the remarkable features in spermatogenesis. In this study, we characterized MIF4GD (MIF4G domain containing), a possible translational regulator, to uncover the function during rat spermatogenesis. Western blot analysis revealed the presence of two forms of MIF4GD with molecular sizes of 25 and 16 kDa in vari...

Successful spermatogonial transplantation requires depletion of the host germ cells to allow efficient colonization of the donor spermatogonial stem cells. Although a sterilizing drug, busulfan (Myleran), is commonly used for preparing a recipient mouse before transplantation, the optimal dose of this drug has not yet been defined. The present study investigated the effects of different doses o...

Round spermatids contain high levels of extremely varied mRNAs that are synthesized either throughout early spermatogenesis or during spermiogenesis from the haploid genome. Concomitantly, with major changes in the chromatin organization, arrest of transcription occurs at midspermiogenesis. However, previous investigations using RT-PCR have revealed the persistence of numerous and different tra...

N6-methyladenosine (m6A) represents one of the most common RNA modifications in eukaryotes. Specific m6A writer, eraser, and reader proteins have been identified. As an m6A eraser, ALKBH5 specifically removes m6A from target mRNAs and inactivation of Alkbh5 leads to male infertility in mice. However, the underlying molecular mechanism remains unknown. Here, we report that ALKBH5-mediated m6A er...

The genome of male germ cells is actively transcribed during spermatogenesis to produce phase-specific protein-coding mRNAs and a considerable amount of different noncoding RNAs. Ribonucleoprotein (RNP) granule-mediated RNA regulation provides a powerful means to secure the quality and correct expression of the requisite transcripts. Haploid spermatids are characterized by a unique, unusually l...

Telomere-capping complexes (TCCs) protect the ends of linear chromosomes from illegitimate repair and end-to-end fusions and are required for genome stability. The identity and assembly of TCC components have been extensively studied, but whether TCCs require active maintenance in nondividing cells remains an open question. Here we show that Drosophila melanogaster requires Deadbeat (Ddbt), a s...

The aim of this study was the evaluation of DNA flow cytometry for the analysis of male infertility. 171 ejaculates from 155 patients with fertility problems were analysed by flow cytometry and by conventional microscopical procedures. Using flow cytometry, it was possible to determine the relative proportions of the various cell populations: mature haploid and abnormal diploid mature spermatoz...