Ruediger Behr

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The differentiation of insulin-producing beta-cells has been investigated in great detail; however, little is known about the factors that delineate the second-most abundant endocrine lineage, the glucagon-producing alpha-cell. Here we utilize a novel YAC-based Foxa3Cre transgene to delete the winged helix transcription factor Foxa2 (formerly HNF-3beta) in(More)
Naive pluripotency is manifest in the preimplantation mammalian embryo. Here we determine transcriptome dynamics of mouse development from the eight-cell stage to postimplantation using lineage-specific RNA sequencing. This method combines high sensitivity and reporter-based fate assignment to acquire the full spectrum of gene expression from discrete(More)
Mice lacking the functional cAMP responsive element modulator (CREM) gene, a component of cAMP-mediated signal transduction, exhibit a specific arrest of round spermatid development although follicle stimulating hormone (FSH) and androgen secretion are not impaired. We studied testicular expression of CREM protein by immunocytochemistry in four patients(More)
Spermatogenesis is a highly complex cell differentiation process that is governed by unique transcriptional regulation and massive chromatin alterations, which are required for meiosis and postmeiotic maturation. The underlying mechanisms involve alterations to the epigenetic layer, including histone modifications and incorporation of testis-specific(More)
BACKGROUND Embryonic stem cells (ESC) hold great promise for the treatment of degenerative diseases. However, before clinical application of ESC in cell replacement therapy can be achieved, the safety and feasibility must be extensively tested in animal models. The common marmoset monkey (Callithrix jacchus) is a useful preclinical non-human primate model(More)
Fertilization of Xenopus laevis eggs triggers a wave of increased [Ca2+]i. The exact signal transduction pathway culminating in this Ca2+ wave remains unknown. To determine whether increases in tyrosine kinase activity are part of this pathway, we microinjected tyrosine kinase inhibitors into unfertilized eggs. Upon fertilization, signs of activation were(More)
The maternal nucleolus is required for proper activation of the embryonic genome (EGA) and early embryonic development. Nucleologenesis is characterized by the transformation of a nucleolar precursor body (NPB) to a mature nucleolus during preimplantation development. However, the function of NPBs and the involved molecular factors are unknown. We uncover a(More)
Seminomas are characterized by expression of several stem cell markers, supporting their origin from germ cells. The current study focuses on novel germ cell markers in normal testes compared to those in fetal testes and different progression stages of seminomas. Microarray data were followed by RT-PCRs and immunohistochemistry on pure seminomas (pT1 to(More)
The seminiferous epithelium in the nonhuman primate Callithrix jacchus is similarly organized to man. This monkey has therefore been used as a preclinical model for spermatogenesis and testicular stem cell physiology. However, little is known about the developmental dynamics of germ cells in the postnatal primate testis. In this study, we analyzed testes of(More)
BACKGROUND Histone to protamine exchange, in man, is only 80% complete and spermatozoal histones are highly acetylated suggesting that their associated genes may be involved in early gene expression in the embryo. METHODS Using in situ hybridization and immunocytochemistry, we analyzed expression of protamine-1 and protamine-2, and histone H4 specifically(More)