Search results for "oogenesis"

Identification and characterization of a constitutive HSP75 in sea urchin embryos.

1997

Abstract An antiserum against a hsp of the 70-kDa family was prepared, by means of a fusion protein, which was able to detect a constitutive 75-kDa hsc in the sea urchinP. lividus.This hsc was present both during oogenesis and at all developmental stages. A two-dimensional electrophoresis has revealed four isolectric forms of this 75-kDa hsc. The amino acid sequence of the fragment used to prepare the anti-hsp70 antibodies revealed a 43% identity with the corresponding part of sea urchin sperm receptor, and in mature eggs a brighter immunofluorescence was seen all around the cell cortex where the receptor for sea urchin sperm is localized. In oocytes the hsp75 was localized in the cytoplasm…

Evidence for the mechanosensor function of filamin in tissue development

2016

AbstractCells integrate mechanical properties of their surroundings to form multicellular, three-dimensional tissues of appropriate size and spatial organisation. Actin cytoskeleton-linked proteins such as talin, vinculin and filamin function as mechanosensors in cells, but it has yet to be tested whether the mechanosensitivity is important for their function in intact tissues. Here we tested, how filamin mechanosensing contributes to oogenesis in Drosophila. Mutations that require more or less force to open the mechanosensor region demonstrate that filamin mechanosensitivity is important for the maturation of actin-rich ring canals that are essential for Drosophila egg development. The ope…

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…

The impact of ovarian stimulation on the expression of candidate reprogramming genes in mouse preimplantation embryos.

2012

Ovarian stimulation with gonadotrophins is an integral part of assisted reproductive technologies in human subfertility/infertility treatment. Recent findings have associated ovarian stimulation with the increased incidence of imprinting disorders in humans as well as defects in genome-wide methylation reprogramming and, in particular, imprinting in mice. Here, we present the first study that determined the impact of ovarian stimulation on the expression of developmentally important reprogramming genes <i>(Apex1, Lig1, Lig3, Mbd2, Mbd3, Mbd4, </i>and<i> Polb)</i> in single early mouse morula embryos (16-cell stage). Using absolute quantification of mRNA by quantitati…

Regulation of vitellogenesis in Nereis virens (Annelida: Polychaeta): effect of estradiol-17beta on eleocytes.

2005

Abstract In the marine polychaete Nereis virens , the yolk protein precursor vitellogenin (Vg) is synthesized in specialized coelomic cells (eleocytes) during oogenesis. This process was visualized by immunohistochemistry using antibodies raised against the yolk protein. Transversal sections from male and female worms confirmed that eleocytes from females but not from males produce Vg. In order to investigate the hormonal regulation of Vg synthesis, eleocytes were incubated in vitro with estradiol-17β (E 2 ) at a concentration of 1 μg/l for up to three days. A strong increase in Vg secretion was detected by ELISA in culture media of treated eleocytes from vitellogenic females. In contrast, …

MITOCHONDRIAL MASS, DISTRIBUTION AND ACTIVITY DURING SEA URCHIN OOGENESIS

2015

The sea urchin egg is a favourite model for studies of the molecular biology and physiology of fertilization and early development, yet we know sparingly little of its oocytes and of mitochondria behaviour during oogenesis. The process of oogenesis in most echinoderms is asynchronous so each ovary lobe has hundreds of oocytes at all stages of development. At the beginning of oogenesis, the oocyte is about 10 µm in diameter. During the vitellogenic phase of oogenesis, the oocyte accumulate yolk proteins and grow to ten times their original size to 80 to 100 µm in sea urchins. The oocyte, arrested at the prophase of the first meiotic division, is apparent with its large nucleus, the germinal …

Studies on sea urchin oocytes. II. Synthesis of RNA during oogenesis.

1972

Abstract Isolated oocytes of the sea urchin Paracentrotus lividus actively incorporate 3H-uridine into RNA. Labeled RNA was analysed by sucrose gradient and acrylamide gel electrophoresis following cell fractionation. Much of the radioactivity is incorporated at the nucleolar level in the form of rRNA precursors. The kinetics of maturation of these latter suggests that this occurs at a slower rate than during embryogenesis. Other non-nucleolar RNA classes are also actively labelled and retained in the nucleus for many hours. These results are confirmed by an autoradiographic investigation.

P. lividus oogenesis and early development require autophagy

2014

It is well known that autophagy is a major intracellular pathway for the degradation and recycling of cytosolic components, in both basal and stress conditions. We have recently demonstrated the activation of autophagy in P. lividus embryos: at high levels, after a stress induced by cadmium, and at basal levels, during the physiological development (1) (2). Here we report ours recent data about autophagy during oogenesis and segmentation. In order to detect autophagolysosomes (AVOs) and autolysosomes, we respectively performed incubation in vivo with acridine orange (AO), and in situ immunofluorescence (IF) with the anti-LC3 antibody (autophagy marker). All observations were carried out by …

2002

Analysis of gonad organization and development revealed that Serranus atricauda is a functional simultaneous hermaphrodite. The ovary is classified as asynchronous. Oocyte growth is divided into five stages: stage I (primary growth stage), stage II (yolk vesicle formation), stage III (vitellogenesis), stage IV (oocyte maturation) and stage V (mature egg). The testis is of the unrestricted or lobular spermatogonial type. Spermatogenic cells include spermatogonia, primary and secondary spermatocytes, spermatids (which form cysts in the seminiferous tubules) and spermatozoa (free in the lumen). The histological structure of the gonad and sperm morphology would seem to indicate that this specie…

Cyclic AMP-dependent and independent stimulations of ovarian steroidogenesis by brain factors in the blowfly, Phormia regina.

2000

0303-7207 doi: DOI: 10.1016/S0303-7207(00)00312-9; The involvement of cyclic-AMP (cAMP) as a potential second messenger in the neurohormonal control of ovarian steroidogenesis was investigated in the adult female blowfly Phormia regina. Individual measurements of ovarian cAMP concentrations and of ovarian biosynthesis of ecdysteroids, stimulated after a protein meal, demonstrated that steroidogenesis is preceded by a peak of cAMP in the ovaries. In vitro, ovarian steroidogenesis was stimulated by cell-permeable analogues of cAMP and by forskolin. Crude brain extracts were also able to elicit a rise of cAMP in the ovaries in vitro and the secretion of ecdysteroids into the medium: such extra…