The Fragilis interferon-inducible gene family of transmembrane proteins is associated with germ cell specification in mice

Background  

Specification of primordial germ cells in mice depends on instructive signalling events, which act first to confer germ cell competence on epiblast cells, and second, to impose a germ cell fate upon competent precursors. fragilis, an interferon-inducible gene coding for a transmembrane protein, is the first gene to be implicated in the acquisition of germ cell competence.     

<Emphasis Type="Italic">Dppa3 / Pgc7 / stella</Emphasis> is a maternal factor and is not required for germ cell specification in mice

Background  

In mice, germ cells are specified through signalling between layers of cells comprising the primitive embryo. The function of Dppa3 (also known as Pgc7 or stella), a gene expressed in primordial germ cells at the time of their emergence in gastrulating embryos, is unknown, but a recent study has claimed that it plays a central role in germ cell specification.     

Germ cell development in the Honeybee (Apis mellifera); Vasa and Nanos expression

Background  

Studies of specification of germ-cells in insect embryos has indicated that in many taxa the germ cells form early in development, and their formation is associated with pole plasm, germ plasm or an organelle called the oosome. None of these morphological features associated with germ cell formation have been identified in the Honeybee Apis mellifera. In this study I report the cloning and expression analysis of Honeybee homologues of vasa and nanos, germ cell markers in insects and other animals.     

Identification of ERβ1 and ERβ2 in human seminoma, in embryonal carcinoma and in their adjacent intratubular germ cell neoplasia

Background  

Estrogens exert a role on germ cell physiology of normal human testis through the mediation of the estrogen receptor (ER) beta subtypes. Epidemiological studies evidenced an increased incidence of testicular germ cell cancer after elevated pre-natal estrogen exposure but the expression of estrogen receptors in these testicular neoplasms has not been well elucidated.     

On the number of founding germ cells in humans

Background  

The number of founding germ cells (FGCs) in mammals is of fundamental significance to the fidelity of gene transmission between generations, but estimates from various methods vary widely. In this paper we obtain a new estimate for the value in humans by using a mathematical model of germ cell development that depends on available oocyte counts for adult women.     

Reinstatement of "germinal epithelium" of the ovary

Background  

The existing dogma that the former term ovarian "germinal epithelium" resulted from a mistaken belief that it could give rise to new germ cells is now strongly challenged.     

Differences in polyadenylation site choice between somatic and male germ cells

Background  

We have previously noted that there were differences in somatic and male germ cell polyadenylation site choices. First, male germ cells showed a lower incidence of the sequence AAUAAA (an important element for somatic polyadenylation site choice) near the polyadenylation site choice. Second, the polyadenylation sites chosen in male germ cells tended to be nearer the 5' end of the mRNA than those chosen in somatic cells. Finally, a number of mRNAs used a different polyadenylation site in male germ cells than in somatic cells. These differences suggested that male germ cell-specific polyadenylation sites may be poor substrates for polyadenylation in somatic cells. We therefore hypothesized that male germ cell-specific polyadenylation sites would be inefficiently used in somatic cells.     

Impact of methoxyacetic acid on mouse Leydig cell gene expression

Background  

Methoxyacetic acid (MAA) is the active metabolite of the widely used industrial chemical ethylene glycol monomethyl ether, which is associated with various developmental and reproductive toxicities, including neural toxicity, blood and immune disorders, limb degeneration and testicular toxicity. Testicular toxicity is caused by degeneration of germ cells in association with changes in gene expression in both germ cells and Sertoli cells of the testis. This study investigates the impact of MAA on gene expression in testicular Leydig cells, which play a critical role in germ cell survival and male reproductive function.     

Enhanced ERbeta immunoexpression and apoptosis in the germ cells of cimetidine-treated rats

Background  

Cimetidine, refereed as antiandrogenic drug, causes hormonal changes in male patients such as increased testosterone and FSH levels. In the rat testis, structural alterations in the seminiferous tubules have been related to germ cell loss and Sertoli cell death by apoptosis. Regarding the important role of Sertoli cells in the conversion of testosterone into estrogen, via aromatase, the immunoexpression of estrogen receptors-beta (ERbeta) was evaluated in the germ cells of untreated and treated rats with cimetidine. A relationship between ERbeta immunoreactivity and apoptosis was also investigated in the germ cells of damaged tubules.     

Characterization of eight novel proteins with male germ cell-specific expression in mouse

Background  

Spermatogenesis and fertilization are highly unique processes. Discovery and characterization of germ cell-specific genes are important for the understanding of these reproductive processes. We investigated eight proteins encoded by novel spermatogenic cell-specific genes previously identified from the mouse round spermatid UniGene library.     

Different DNA methylation patterns detected by the Amplified Methylation Polymorphism Polymerase Chain Reaction (AMP PCR) technique among various cell types of bulls

Background  

The purpose of this study was to apply an arbitrarily primed methylation sensitive polymerase chain reaction (PCR) assay called Amplified Methylation Polymorphism Polymerase Chain Reaction (AMP PCR) to investigate the methylation profiles of somatic and germ cells obtained from Holstein bulls.     

Impact of proximal cytoplasmic droplets on quality traits and in-vitro embryo production efficiency of cryopreserved bull spermatozoa

Background  

Proximal cytoplasmic droplets (PCDs), a remnant of germ cell cytoplasm, are common non-specific morphological defects in bovine semen. This study evaluated the effect of higher percentages of PCDs on the quality of frozen-thawed bovine semen, embryo production and early embryo development.     

Transforming growth factor beta-1 decreases the yield of the second meiotic division of rat pachytene spermatocytes <Emphasis Type="Italic">in vitro</Emphasis>

Background  

TGF beta and its receptors are present in both germ cells and somatic cells of the male gonad. However, knock-out strategies for studying spermatogenesis regulation by TGF beta have been disappointing since TGF beta-or TGF beta receptor-null mice do not survive longer than a few weeks.     

The CMV early enhancer/chicken β actin (CAG) promoter can be used to drive transgene expression during the differentiation of murine embryonic stem cells into vascular progenitors

Background  

Mouse embryonic stem cells cultured in vitro have the ability to differentiate into cells of the three germ layers as well as germ cells. The differentiation mimics early developmental events, including vasculogenesis and early angiogenesis and several differentiation systems are being used to identify factors that are important during the formation of the vascular system. Embryonic stem cells are difficult to transfect, while downregulation of promoter activity upon selection of stable transfectants has been reported, rendering the study of proteins by overexpression difficult.     

Conserved and divergent patterns of expression of DAZL,VASA and OCT4 in the germ cells of the human fetal ovary and testis

Background  

Germ cells arise from a small group of cells that express markers of pluripotency including OCT4. In humans formation of gonadal compartments (cords in testis, nests in ovary) takes place during the 1st trimester (6–8 weeks gestation). In the 2nd trimester germ cells can enter meiotic prophase in females whereas in males this does not occur until puberty. We have used qRTPCR, Westerns and immunohistochemical profiling to determine which of the germ cell subtypes in the human fetal gonads express OCT4, DAZL and VASA, as these have been shown to play an essential role in germ cell maturation in mice.     

Loss of spermatogonia and wide-spread DNA methylation defects in newborn male mice deficient in DNMT3L

Background  

Formation of haploid spermatozoa capable of fertilization requires proper programming of epigenetic information. Exactly how DNMT3L (DNA methyltransferase 3-Like), a postulated regulator of DNA methyltransferase activity, contributes to DNA methylation pattern acquisition during gametogenesis remains unclear. Here we report on the role of DNMT3L in male germ cell development.     

Epigenetic reprogramming in the porcine germ line

Background  

Epigenetic reprogramming is critical for genome regulation during germ line development. Genome-wide demethylation in mouse primordial germ cells (PGC) is a unique reprogramming event essential for erasing epigenetic memory and preventing the transmission of epimutations to the next generation. In addition to DNA demethylation, PGC are subject to a major reprogramming of histone marks, and many of these changes are concurrent with a cell cycle arrest in the G2 phase. There is limited information on how well conserved these events are in mammals. Here we report on the dynamic reprogramming of DNA methylation at CpGs of imprinted loci and DNA repeats, and the global changes in H3K27me3 and H3K9me2 in the developing germ line of the domestic pig.