bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zygotic gene activation in the mouse embryo: Involvement of cyclic adenosine monophosphate‐dependent protein kinase and appearance of an AP‐1‐like activity
Authors: Schwartz Daniel A. , Schultz Richard M. 
Published: February 2005

AbstractProtein phosphorylation catalyzed by the cyclic adenosine monophosphate (cAMP)‐dependent protein kinase (PKA) is implicated in regulating zygotic gene activation in the two‐cell mouse embryo (Poueymirou and Schultz; Dev Biol 133:588–599, 1989). We now provide evidence that H8, which is a PKA inhibitor, inhibits expression of an hsp70‐driven β‐galactosidase reporter gene and that the concentration‐dependence of this inhibition is similar to that for inhibiting expression of a stage‐specific gene(s) that is a product of zygotic gene activation. We also demonstrate that neither cAMP nor serum can stimulate the expression, as detected by a histochemical assay, of a cAMP response element (CRE)‐ or serum response element (SRE)‐driven β‐galatosidase reporter gene, respectively in either germinal vesicle‐intact oocytes or aphidicolin‐arrested one‐cell embryos that are chronologically at the tw‐cell stage. In contrast, although 12‐O‐tetradecanoyl phorbol‐13‐acetate (TPA) does not stimulate expression of a TPA response element (TRE)‐driven β‐galatosidase reporter gene in germinal vesicle‐intact oocytes, it stimulates such expression in aphidicolin‐arrested one‐cell embryos. Moreover, TPA can stimulate the expression of either a CRE‐ or an SRE‐driven β‐galatosidase reporter gene in such embryos. Results of these studies further implicate protein phosphorylation in regulating zygotic gene activation, along with its role in modulating enhancer function in the early mouse embryo.
Golden hamster embryonic genome activation occurs at the two‐cell stage: Correlation with major developmental changes
Authors: Seshagiri Polani B. , McKenzie Debbie I. , Bavister Barry D. , Williamson Judy L. , Aiken Judd M. 
Published: February 2005

AbstractThe earliest time of onset of embryonic genome activation in golden hamsters was investigated. The inhibition of transcription by α‐amanitin (11 μg/ml) in cultured embryos resulted in a total arrest of development of early 2‐cell embryos (26 hr post‐egg activation); under similar conditions, immediate cleavage divisions of 1‐, late 2‐, 4‐, and 8‐cell embryos were not affected. Electrophoretic analysis of [35S]methionine‐labeled embryonic proteins showed that α‐amanitin treatment apparently inhibited transcription‐dependent protein synthesis in early 2‐cell and, to some extent, in late 2‐cell when compared to 4‐cell embryos. Analysis of total RNA synthesis, using [α32P]‐UTP or [32P]‐orthophosphate, showed that there was a high proportion of radioactivity associated with the macromolecular fraction (RNA) at the early and late 2‐cell stages and at the 4‐cell stage compared to that at the 1‐cell stage. These results indicate that the de novo synthesis of RNA, encoded by the embryonic genome, occurs at the 2‐cell stage and that the second and subsequent cleavage divisions of hamster preimplantation embryos are dependent on new transcriptional activity. This initial activity of the embryonic genome in hamsters is coincident with several characteristic features of in vitro development such as a block to development, synthesis of major proteins, change in energy substrate preference, phosphate‐inhibition of development and a requirement for amino acids.
Primary culture of human fallopian tube epithelial cells and co‐culture of early mouse pre‐embryos
Authors: Takeuchi Kazuhiro , Nagata Yukihiro , Sandow Bruce A. , Hodgen Gary D. 
Published: February 2005

AbstractWe have established a monolayer culture system for human fallopian tube epithelial cells. The cells were isolated from tubes using collagenase digestion, and were cultured in Ham's F‐10 supplemented with 15% fetal calf serum. The epithelial cells derived from culture were characterized using immunocytochemical staining and electron microscopy. These cells were stained with antikeratin and anti‐epithelial membrane antigen, but showed no staining after treatment with antivimentin. Electron microscopy showed many microvilli on the cell surface and tight junctions or desmosomes at areas of cell‐cell contact. Cell proliferation was enhanced by epidermal growth factor, but not by fibroblast growth factor, insulin, transferrin, estradiol‐17β, or progesterone.The 2‐cell ICR mouse pre‐embryos were co‐cultured for 4 days with tubal epithelial cells (A) (n = 98), in cell‐conditioned medium (B) (n = 83), or in medium alone (C) (n = 72). During the first 24 h in culture, for groups A and B, the rates of cleavage to the 4‐cell stage were 90.9% and 81.9%, respectively. Cleavage rates in these two groups were significantly higher (P =0.0012, P > 0.00001) than in group C (56.9%). After 72 h in culture, the rates of development to the blastocyst stage were significantly higher for groups A and B compared to group C (89.6% and 73.5% vs. 54.5%, P > 0.00001, P = 0.0002). These results suggest that factor(s) from tubal epithelial cells may facilitate the development of mouse pre‐embryos throughout the pre‐implantation stages.
Cleavage rate of diandric triploid mouse embryos during the preimplantation period
Authors: Henery C. C. , Kaufman M. H. 
Published: February 2005

AbstractThe postimplantation development of human and animal triploid embryos is well documented, but there is little informative data on their preimplantation development. An analysis of cell number at appropriate times during this period and thus their cleavage rate would give an indication of the potential triploids have for further development and may explain some problems associated with their postimplantation development. To rule out any effects of technical procedures on cleavage rate, appropriate controls were used. Diandric triploid embryos were produced using standard micromanipulatory techniques, which involved the injection of a male pronucleus into a recipient one‐cell‐stage embryo. The karyoplast was fused to the cytoplasm by electrofusion, and the resulting tripronucleate diandric triploid embryos were transferred to appropriate pseudopregnant recipients. At specific times after the transfer, the embryos were recovered and cell numbers established. The results were plotted and regression lines drawn. Three controls were used (1) micromanipulated diploid embryos from which the male pronucleus had been removed and immediately reinserted and fused to restore diploidy, (2) diploid embryos that had been briefly incubated in cytochalasin D and colcemid to find out the effects these agents had on development, and (3) diploid embryos that had been isolated and briefly incubated in tissue culture medium. All embryos were subsequently transferred to recipients. After isolation at specific times during the preimplantation period, cell numbers were also established and the results plotted. The cell doubling time of the diandric triploid embryos was 13.55 hr (± 1.25), and this was not significantly different from the various controls. The cell doubling time of (1) the micromanipulated controls was 12.12 hr (± 1.16), (2) the control embyros incubated in cytoskeletal inhibitors 10.87 hr (± 0.75), and (3) the group that was briefly incubated in tissue culture 12.43 hr (± 0.74). There was no significant effect of manipulation or incubation in cytoskeletal inhibitors on cleavage rate. Our findings indicate that triploid embryos divide at the same rate as diploid embryos during the preimplantation period.
Morphological development and sex of bovine in vitro‐fertilized embryos
Authors: Avery Birthe , Jørgensen Claus B. , Madison Valerie , Greve Torben 
Published: February 2005

AbstractBovine in vitro‐fertilized embryos at the blastocyst stage were collected at days 7, 8, and 10 postinsemination and sex was determined via the polymerase chain reaction (PCR) to compare the embryonic development with the sex of the embryos. The percentages of males (sex ratio) after division of the embryos into three developmental groups were 68%, 48%, and 35% in the fast, intermediate, and slow groups, respectively (P = 0.014). The percentages of males on days 7, 8, and 10 were 60%, 40% and 33%, respectively (P = 0.043). The average sex ratio for the whole material was 50%. It is thus concluded that male bovine preimplantation embryos develop faster than female embryos.
Synthesis and modification of D7 protein during Xenopusoocyte maturation
Authors: Smith Rosamund C. , Dworkin Mark B. , Dworkin‐Rastl Eva 
Published: February 2005

AbstractThe Xenopus maternal mRNA D7 is translationally repressed during oogenesis, only becoming recruited into polysomes during oocyte maturation, with D7 protein being detectable for the first time prior to germinal vesicle breakdown (GVBD). The synthesis of D7 protein was found to be induced by a variety of maturation‐promoting agents including cyclin, c‐mos and crude preparations of MPF. D7 protein induced by all these agents is post‐translationally modified and exists as a number of variants of differing molecular weight. In contrast to endogenous D7 mRNA, D7 RNA injected into the stage VI oocyte is efficiently translated, resulting in the accumulation of predominantly unmodified D7 polypeptides, which become increasingly modified during oocyte maturation to produce a pattern of polypeptides similar to those derived from endogenous D7 mRNA. Thus, the system that results in the post‐translational modification of the D7 protein is itself activated during oocyte maturation. The nature of the protein modification is not known but does not appear to be phosphorylation. The translation of exogenous D7 RNA in the stage VI oocyte does not lead to translational derepression of endogenous D7 mRNA.
Glycogen breakdown in cleaving xenopus embryos is limited by ADP
Authors: Dworkin Mark B. , Dworkin‐Rastl Eva 
Published: February 2005

AbstractXenopus eggs contain large stores of glycogen, but this glycogen is not glycolytically processed during cleavage. The Embden‐Meyerhof pathway is inhibited by the absence of pyruvate kinase activity in vivo, and lactate and pyruvate are present at relatively low levels. In the late blastula, just preceding gastrulation, lactate levels increase, indicating the onset of glycogen breakdown and glycolytic flux. Glycolysis from microinjected [14C]glucose‐6‐phosphate could be transiently activated, however, by the coinjection of ADP into fertilized eggs, and constitutively activated by the injection of the ATPase potato apyrase, indicating the presence of all enzymes necessary for glycolytic activity. The isozyme profiles of pyruvate kinase and malic enzyme, two enzymes involved in carbon metabolism during cleavage or in the subsequent activation of glycogen breakdown, do not change between the egg and gastrula stages. These data suggest that the activation of glycogen breakdown and glycolysis in the late blastula is probably not a result of new gene activity but may be the metabolic consequence of increased free ADP that is then able to support the pyruvate kinase reaction.
Spatial distribution of active genes implicated in the regulation of insulin‐like growth factor stimulatory loops in human decidual and placental tissue of first‐trimester pregnancy
Authors: Glaser Anna , Luthman Holger , Stern Ingrid , Ohlsson Rolf 
Published: February 2005

AbstractWe have previously shown that the insulin‐like growth factor‐2 (IGF‐2) gene is partially coexpressed with the IGF‐1 and ‐2 receptor genes in proliferative cytotrophoblasts of the human extraembryonic tissue. Here we show that high levels of IGF‐2 gene expression are not restricted to the embryonic tissue but can also be found in the decidua compacta. The IGF‐2 gene is thus expressed at high levels in the mesenchymal stroma of the decidua to establish potentially short‐range communication with primarily IGF‐1 receptor‐positive mesenchymal stroma cells. Conversely, the glandular and surface epithelia coexpress the IGF‐1 receptor and IGF‐1 genes, while the IGF‐2 gene is not detected above background levels. The potential control machanisms of these cell‐cell signalling pathways were investigated by the analysis of the spatial distribution of active IGF binding proteins (IGFBP) genes. The IGFBP‐3 gene is coexpressed with the IGF‐2 gene in proliferative cytotrophoblasts of the embryonic placenta. While active IGFBP‐1 and ‐2 genes in our hands cannot be detected in the embryonic placenta, all three IGFBP genes are expressed in complex and overlapping patterns in the decidua compacta. The results are discussed in terms of how the various IGFBP genes may operate in different cell types to restrict IGF local stimulatory pathways. © 1992 Wiley‐Liss, Inc.
Functional properties of caltrin proteins from seminal vesicle of the guinea pig
Authors: Coronel Carlos E. , Lardy Henry A. 
Published: February 2005

AbstractCaltrin proteins from seminal vesicle content of the guinea pig bind with great specificity to different regions of the spermatozoa. Indirect immunofluorescence studies with polyclonal antibodies showed that caltrin I binds to the head, on the acrosomal cup, while caltrin II binds on the principal tail and the neck. No fluorescence was detected either in the midpiece or in the postacrosomal area of the head when sperm were exposed to either of the caltrins. Calcium‐induced hyaluronidase release, which occurs during the acrosomal reaction, was dramatically inhibited by caltrin I (∼85% inhibition). Caltrin II was less effective in preventing the enzyme release (∼50% inhibition). Chemical modification of the structure modified the biological activity of the two caltrins. Reduction and carboxymethylation of the cysteine residues diminished the inhibitory activity on 45Ca2+ uptake and reduced the ability of the proteins to react with their antibodies. Removal of the carbohydrate portion by chemical deglycosylation transformed the inhibitor proteins into enhancers of calcium uptake into the spermatozoa. Caltrin proteins from the guinea pig appear to play the same physiological role as bovine caltrin, regulating specifically calcium transport across the spermatozoal membranes related with the acrosome reaction and hyperactivation process. The dual behavior of caltrins to inhibit or enhance Ca2+ uptake enables them to fulfill this function. Nevertheless, molecular mechanisms different from those described for bovine caltrin seem to be involved in the control of the functional activity of the guinea pig caltrins. © 1992 Wiley‐Liss, Inc.
Structural organization of surface domains of sperm mitochondria
Authors: Olson Gary E. , Winfrey Virginia P. 
Published: February 2005

AbstractSperm mitochondria are assembled into an organized sheath surrounding the outer dense fibers and axoneme of the flagellar midpiece. Each mitochondrion is arranged so that its surface faces three different cellular organelles including the plasma membrane, neighboring mitochondria and the outer dense fiber–axoneme complex. In this manuscript we present data on structural differentiations of these three different surface domains of the outer mitochondrial membrane. We demonstrate that the apposed surfaces of adjacent mitochondria are joined by a two dimensional network of studs unique to this domain. By contrast, the surface domain facing the outer dense fiber–axoneme complex exhibits a different, but highly ordered structural organization, evident as a parcrystalline network of parallel stripes; this domain is further distinguished by its exclusive association with a midpiece‐specific cytoskeletal complex. These differentiations are not seen on the surface domain of mitochondria which faces the plasma membrane. The implications of the mosaic composition of the outer mitochondrial membrane in the assembly and function of the mitochondrial sheath are discussed. © 1992 Wiley‐Liss, Inc.
Cyclin B in fish oocytes: Its cDNA and amino acid sequences, appearance during maturation, and induction of p34cdc2 activation
Authors: Hirai T. , Yamashita M. , Yoshikuni M. , Lou Y.‐H. , Nagahama Y. 
Published: February 2005

AbstractUnder the influence of maturation‐inducing hormone (MIH) secreted from follicle cells, oocyte maturation is finally triggered by maturation‐promoting factor (MPF), which consists of a homolog of the cdc2+ gene product of fission yeast (p34cdc2) and cyclin B. Two species of cyclin B clones were isolated from a cDNA library constructed from mature goldfish oocytes. Sequence comparisons revealed that these two clones are highly homologous (95%) and were found to be similar to Xenopus cyclin B1. Using monocional antibodies against Escherichia coli produced goldfish cyclin B and the PSTAIR sequence of p34cdc2, we examined the levels of cyclin B and p34cdc2 proteins during goldfish oocyte maturation induced in vitro by 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐DP), a natural MIH in fish. Protein p34cdc2 was found in immature oocyte extracts and did not remarkably change during oocyte maturation. Cyclin B was not detected in immature oocyte extracts and appeared when oocytes underwent germinal vesicle breakdown. Cyclin B that appeared during oocyte maturation was labelled with [35S]methionine, indicating its de novo synthesis. Introduction of E. coli‐produced cyclin B into immature oocyte extracts induced p34cdc2 (MPF) activation. Although the possibility that immature goldfish oocytes contain an insoluble cyclin B is not completely excluded, these results strongly suggest that 17α, 20β‐DP induced oocytes to synthesize cyclin B, which in turn activates preexisting p34cdc2, forming active MPF. © 1992 Wiley‐Liss, Inc.
Vitrification of mouse oocytes using short cryoprotectant exposure: Effects of varying exposure times on survival
Authors: Shaw P. W. , Bernard A. G. , Fuller B. J. , Hunter J. H. , Shaw R. W. 
Published: February 2005

AbstractThe effects on oocyte viability of varying the duration of exposure to cryoprotectants before rapid cooling to – 196°C were examined, using the vitrification protocol of Nakagata. A very short exposure (15 sec) was found to be optimal, resulting in an overall rate of development from vitrified oocytes to hatching blastocysts of 31.8%. Very high rates of survival (77–89%) of oocytes exposed to the cryoprotectant media, but without the vitrification, together with extreme variability in results between straws in the vitrified groups, suggest that losses in viability during vitrification may result from ice damage during devitrification of the medium. (c) 1992 Wiley‐Liss, Inc.
Demonstration of a stage‐specific expression of the zfy protein in fetal mouse testis using anti‐peptide antibodies
Authors: Su Hua , Lau Yun‐Fai Chris 
Published: February 2005

AbstractThe zinc finger Y (Zfy) gene is located on the Y chromosome of all placental mammals. Although it is phylogenetically conserved and is expressed in mouse fetal testis, it is not the sex determining Y (Tdy) gene. To address the possible function of the Zfy gene in mice, the distribution of Zfy protein in fetal mice was investigated by immunocytochemical staining using several specific antisera against synthetic peptides of the mouse Zfy protein. Analysis of various fetal tissues at different embryonic stages demonstrated a specific staining only in fetal testis. In particular, reactive protein was initially observed in male fetal gonads at day 11.5 postcoitum (p.c.). The immuno‐staining intensified in fetal testes at day 12 and 12.5 p.c., decreased drastically in those at day 13 and 14 p.c. and became undetectable in those at day 15 p.c. and beyond. The reactive molecules were distributed mostly within the seminiferous tubules of the embryonic testis. The present observations confirm the previous findings with RT‐PCR analysis and indicate that Zfy or Zfy‐like protein is expressed in stage‐specific manner during early testis differentiation. Its location in the seminiferous tubules suggests a possible role in early germ cell development. © 1992 Wiley‐Liss, Inc.
Characterization of male meiotic germ cell‐specific antigen (Meg 1) by monoclonal antibody TRA 369 in mice
Authors: Watanabe Daisuke , Sawada Ken , Koshimizu Uichi , Kagawa Tsutomu , Nishimune Yoshitake 
Published: February 2005

AbstractWe have identified a male meiotic germ cell‐specific antigen (Meg 1) with monoclonal antibody (mAb) TRA 369 in mice. The Meg 1 antigen was strongly expressed in specific steps of meiotic germ cells from pachytene spermatocyte to early spermatid, and not in other germ cells or somatic cells. Immunohistochemical examination revealed that the antigen was localized to the cytoplasm and was not distributed in the nucleus or on the cell surface. This antigen was demonstrated to have a molecular weight of 93 kDa and an isoelectric point of 5.2 by Western blotting. This molecule was first detected in the testis of 13‐day‐old mouse when pachytene spermatocytes first appeared. Thus this is a differentiation‐specific antigen in male meiotic germ cells, and mAb TRA 369 is a useful tool to study the regulation of germ cell differentiation and to define germ cell development in a molecular level. © 1992 Wiley‐Liss, Inc.
Protein synthesis requirements during resumption of meiosis in the hamster oocyte: Early nuclear and microtubule configurations
Authors: Plancha Carlos E. , Albertini David F. 
Published: February 2005

AbstractThe organization of chromatin and cytoplasmic microtubules changes abruptly at M‐phase entry in both mitotic and meiotic cell cycles. To determine whether the early nuclear and cytoplasmic events associated with meiotic resumption are dependent on protein synthesis, cumulus‐enclosed hamster oocytes were cultured in the presence of 100 μg/ml puromycin or cycloheximide for 5 hr. Both control (untreated) and treated oocytes were analyzed by fluorescence microscopy after staining with Hoechst 33258 and tubulin antibodies. Freshly isolated oocytes exhibit prominent nucleoli and diffuse chromatin within the germinal vesicle as well as an interphase network of cytoplasmic microtubules. After 4–4.5 hr in culture, most oocytes were in prometaphase I of meiosis as characterized by a prominent spindle with fully condensed chromosomes and numerous cytoplasmic asters. After 5–5.5 hr in culture, microtubule asters are no longer detected in most cells and the spindle is the only tubulin‐positive structure. Incubation for 5 hr in the presence of inhibitors does not impair germinal vesicle breakdown, chromatin condensation, kinetochore microtubule assembly, or cytoplasmic aster formation in the majority of oocytes examined; however, under these conditions, a population of oocytes retains a germinal vesicle, exhibiting variable degrees of chromatin condensation and cytoplasmic aster formation. Meiotic spindle formation in inhibited in all oocytes. These effects are fully reversible upon culture of treated oocytes in drug‐free medium for 5 hr. The data indicate that meiotic spindle assembly is dependent on ongoing protein synthesis in the cumulus‐enclosed hamster oocyte; in contrast, chromatin condensation and aster formation are not as sensitive to protein synthesis inhibitors during meiotic resumption. © 1992 Wiley‐Liss, Inc.