Search results for "meiosis"
showing 10 items of 55 documents
RADHA - a new male germ line-specific chromosomal protein of Drosophila
1999
A new chromosomal protein - RADHA - of Drosophila is described that is specific for the male germ line. It is encoded by a single-copy gene, located in the region 96C-D of D. melanogaster polytene chromosomes. Transcription of the radha gene is restricted to the primary spermatocyte stage. The protein initially accumulates in some of the Y-chromosomal lampbrush loops. After meiosis it is found in the nuclei of spermatids and might be involved in chromatin rearrangement processes in the male germ line. RADHA is a basic protein with a C-terminal leucine zipper region and several segments capable of forming coiled-coil structures.
Stage-specific germ-cell marker genes are expressed in all mouse pluripotent cell types and emerge early during induced pluripotency.
2011
Embryonic stem cells (ESCs) generated from the in-vitro culture of blastocyst stage embryos are known as equivalent to blastocyst inner cell mass (ICM) in-vivo. Though several reports have shown the expression of germ cell/pre-meiotic (GC/PrM) markers in ESCs, their functional relevance for the pluripotency and germ line commitment are largely unknown. In the present study, we used mouse as a model system and systematically analyzed the RNA and protein expression of GC/PrM markers in ESCs and found them to be comparable to the expression of cultured pluripotent cells originated from the germ line. Further, siRNA knockdown experiments have demonstrated the parallel maintenance and independen…
Skeletal abnormalities of the upper limbs--neonatal diagnosis of 49,XXXXY syndrome.
2012
A case of neonatal diagnosis of 49,XXXXY syndrome is presented. Clinical identification was prompted by a bilateral thickening of the radioulnar joints and X-ray imaging disclosing almost complete radioulnar synostosis. Conventional karyotyping was initiated and revealed a karyotype of 49,XXXXY. Previously reported neonatal symptoms such as low birth weight, muscular hypotonia, or genital malformations were absent in this case. Microsatellite analysis showed two different X chromosomes each present in two copies, supporting that the four X chromosomes had arisen from a nondisjunction in maternal meiosis I followed by a second nondisjunction involving both X chromosomes in meiosis II. Multid…
Virus-like particles, bacteria and microsporidia affect spindle-associated membranes in spermatocytes of Lepidoptera species.
1997
SummaryLarval testes of four Lepidoptera species were examined using electron microscopy. The testes of one species, the Mediterranean mealmothEphestia kuehniella(Pyralidae), were devoid of intracellular pathogens and serve as a control. In this species, metaphase spindles of primary spermatocytes showed a thick layer of perispindle membranes. The membranes were structurally very similar to the agranular endoplasmic reticulum. Membranes of this type occurred also at high frequency throughout the spindle matrix. The analysis of larval testes ofPieris brassicae(Pieridae) revealed virus-like particles within spermatocytes. In another species,Philudoria potatoria(Lasiocampidae), the spermatocyt…
PSCDGs of mouse multipotent adult germline stem cells can enter and progress through meiosis to form haploid male germ cells in vitro
2010
Spermatogonial stem cells (SSCs) provide the basis for spermatogenesis throughout adult life by undergoing self-renewal and differentiation into sperm. SSC-derived cell lines called multipotent adult germline stem cells (maGSCs) were recently shown to be pluripotent and to have the same potential as embryonic stem cells (ESCs). In a differentiation protocol using retinoic acid (RA) and based on a double selection strategy, we have shown that ESCs are able to undergo meiosis and produce haploid male germ cells in vitro. Using this differentiation protocol we have now succeeded to generate haploid male germ cells from maGSCs in vitro. maGSCs derived from a Stra8-EGFP transgenic mouse line wer…
CEP63 deficiency promotes p53-dependent microcephaly and reveals a role for the centrosome in meiotic recombination
2015
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM
Human somatic cells subjected to genetic induction with six germ line-related factors display meiotic germ cell-like features
2016
AbstractThe in vitro derivation of human germ cells has attracted interest in the last years, but their direct conversion from human somatic cells has not yet been reported. Here we tested the ability of human male somatic cells to directly convert into a meiotic germ cell-like phenotype by inducing them with a combination of selected key germ cell developmental factors. We started with a pool of 12 candidates that were reduced to 6, demonstrating that ectopic expression of the germ line-related genes PRDM1, PRDM14, LIN28A, DAZL, VASA and SYCP3 induced direct conversion of somatic cells (hFSK (46, XY) and hMSC (46, XY)) into a germ cell-like phenotype in vitro. Induced germ cell-like cells …
The human X chromosome is enriched for germline genes expressed in premeiotic germ cells of both sexes.
2006
The role of X-chromosomal genes in spermatogenesis has been subject to a number of studies in different organisms. Recently, it was proposed that the X chromosome has a predominant role in premeiotic stages of mammalian spermatogenesis. We analyzed the expression of a representative set of 17 X-linked and 48 autosomal germline-restricted genes in different stages of human germ cell development. In accordance with data from other species, we show that the human X chromosome is indeed significantly enriched for genes activated in premeiotic stages of spermatogenesis. In contrast to recent studies, however, we found that expression of these genes is not restricted to spermatogenesis, but is ac…
Histone modifications in the male germ line of Drosophilaa
2013
Abstract Background In the male germ line of Drosophila chromatin remains decondensed and highly transcribed during meiotic prophase until it is rapidly compacted. A large proportion of the cell cycle-regulated histone H3.1 is replaced by H3.3, a histone variant encoded outside the histone repeat cluster and not subject to cell cycle controlled expression. Results We investigated histone modification patterns in testes of D. melanogaster and D. hydei. In somatic cells of the testis envelope and in germ cells these modification patterns differ from those typically seen in eu- and heterochromatin of other somatic cells. During the meiotic prophase some modifications expected in active chromat…
Origin and ploidy of multipronuclear zygotes
2000
Recently, several authors have proposed strategies for correction of triploidy based on the removal of the extra pronucleus at the zygote stage. In the present bioassay, the following were analysed: (1) the different factors that can induce the formation of multipronuclear zygotes in mammals; (2) the different morphological patterns established according to the number of pronuclei and polar bodies that can be observed at the zygote stage and used to distinguish the origin of multipronuclear zygotes; and (3) the pattern of chromosomal segregation during the first mitotic division and ploidy status of the resulting preim-plantation embryos. Such an analysis shows that the morphological crite…