bluuebunny/crossref_metadata_2025_split huggingface dataset:
TGF‐β receptors
Authors: Massagué Joan , Andres Janet , Attisano Liliana , Cheifetz Sela , López‐Casillas Fernando , Ohtsuki Masahiko , Wrana Jeffrey L. 
Published: February 2005

AbstractThe nature and role of cell surface proteins that bind members of the TGF‐β family has been investigated. TGF‐β, activins, and BMPs each bind to receptors of 55 kDa (type I) and 70 kDa (type II). In the TGF‐β system, these receptors are implicated in the mediation of multiple responses. A member of the type II receptor family has been cloned that encodes four alternatively spliced versions of a transmembrane serine/threonine kinase receptor related to the recently cloned mouse activin receptor and C‐elegans daf‐1 gene. Inhibitors of serine/threonine kinase activity block transcriptional and growth inhibitory responses to TGF‐β. In addition to the signaling receptors, many cell types express the TGF‐β binding proteoglycan betaglycan. Betaglycan has been purified, molecularly cloned, and shown to bind TGF‐β via its core protein and basic fibroblast growth factor via its heparan sulfate chains. In addition to receptors I and II and betaglycan, some cells express a newly identified set of membrane proteins that specifically bind either TGF‐β1 or TGF‐β2. Three of the four isoform‐restricted binding proteins are bound to the membrane via phospholipid anchors. Like betaglycan, these proteins might function to regulate the interaction between TGF‐β and their target cells. © 1992 Wiley‐Liss, Inc.
TGF‐β family factors in Drosophila morphogenesis
Authors: Hoffmann F. Michael 
Published: February 2005

AbstractMany Drosophila genes have now been identified with substantial sequence similarity to vertebrate protooncogenes and growth factors. Some of these have been isolated directly by cross‐hybridization with vertebrate probes and some have been recognized in the sequences of genes cloned because of their intiguing mutant phenotypes. An example of a gene isolated for its interesting development functions but with homology to a vertebrate growth factor is the Drosophila decapentaplegic gene (dpp). An example of a Drosophila gene isolated by virtue of its sequence conservation is the vgr/60A gene. Both dpp and vgr/60A are members of the transforming growth factor‐β family and are most similar to the human bone morphogenetic proteins. The regulation of the dpp gene by several different groups of pattern formation genes including the dorsal/ventral group, the terminal group, the segment polarity genes, and the homeotic genes indicates that many events in embryogenesis require the cell to cell communication mediated by the secreted dpp protein. The temporal and spatial pattern of vgr/60A expression differs from that of dpp indicating that it may be regulated by different pattern information genes. The experimental advantages of the Drosophila system should permit a better understanding of the importance of growth factor homologs in specific developmental events, aid in establishing the functional interactions between these regulatory molecules, and identify new genes that are important for the biological functions of growth factors. It is likely that some of the newly identified genes will have vertebrate homologs and the analysis of these may be helpful in studies on vertebrate development and tumor biology. © 1992 Wiley‐Liss, Inc.
The sperm entry site during fertilization of the zebrafish egg: Localization of actin
Authors: Hart Nathan H. , Becker Karen A. , Wolenski Joseph S. 
Published: February 2005

AbstractThe sperm entry site (SES) of zebrafish (Brachydanio rerio) eggs was studied before and during fertilization by fluorescence, scanning, and transmission electron microscopy. Rhodamine phalloidin (RhPh), used to detect polymerized filamentous actin, was localized to microvilli of the SES and to cytoplasm subjacent to the plasma membrane in the unfertilized egg. The distribution of RhPh staining at the SES correlated with the ultrastructural localization of a submembranous electrondense layer of cortical cytoplasm approximately 500 nm thick and containing 5‐ to 6‐nm filaments. Actin, therefore, was organized at the SES as a tightly knit meshwork of filaments prior to fertilization. Contact between the fertilizing sperm and the filamentous actin network was observed by 15–20 sec postinsemination or just before the onset of fertilization cone formation. Growing fertilization cones of either artificially activated or inseminated eggs exhibited intense RhPh staining and substantial increase in thickness of the actin meshwork. Collectively, TEM and RhPh fluorescence images of inseminated eggs demonstrated that the submembranous actin became rearranged in fertilization cones to form a thickened meshwork around the sperm nucleus during incorporation. The results reported here suggest that activation of the egg triggers a dramatic polymerization of actin beneath the plasma membrane of the fertilization cone. Furthermore, the actin involved in sperm incorporation is sensitive to the action of cytochalasins.
Rabbit blastocysts accumulate platelet‐activating factor (PAF) and lyso‐PAF in vitro
Authors: Jones M. A. , Kudolo G. B. , Harper M. J. K. 
Published: February 2005

AbstractPlatelet‐activating factor (1‐O‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphorylcholine; PAF) is a very potent phospholipid, which has been demonstrated to stimulate smooth muscle and change vascular permeability. PAF has been detected in the rabbit preimplantation uterine endometrium and has been demonstrated to bind specifically to rabbit uterine membranes. To evaluate the possible role of PAF in maternal‐embryonic chemical communication, we report here that rabbit blastocysts can accumulate [3H]PAF from their environment. Blastocysts were able to accumulate [3H]PAF as time‐, buffer‐, age‐, and concentration‐dependent functions. The accumulation was inhibited by some PAF receptor antagonists, such as U66985, as well as by unlabeled PAF and lyso‐PAF, indicating that the accumulation process may be receptor mediated. The data support the current model of PAF as a paracrine factor in preimplantation stages of reproduction.
Purification and characterization of a vitelline coat lysin from Ciona intestinalis spermatozoa
Authors: Marino Rita , De Santis Rosaria , Hirohashi Noritaka , Hoshi Motonori , Pinto Maria Rosaria , Usui Noriko 
Published: February 2005

AbstractIn Ciona intestinalis a chymotrypsin‐like activity is involved in sperm penetration of the egg vitelline coat. A chymotrypsin‐like enzyme has been purified from spermatozoa by a protocol including ion exchange chromatography, gel filtration, and native polyacrylamide gel electrophoresis. The purified enzyme resulted homogeneous when analyzed by SDS‐PAGE. The molecular weight of the chmotrypsin‐like enzyme was estimated to be 35 KDa by gel filtration and 24 KDa by SDS‐PAGE in nonreducing conditions. The pH optimum of the enzyme is 8.4 and its activity is enhanced by Ca2+. It shows the highest activity towards the synthetic substrate Suc‐Ala‐Ala‐Pro‐Phe‐AMC. Furthermore, by electron microscopy, the purified enzyme affects the structure of egg vitelline coat, and thus it fulfills one of the criteria of a lysin.
Myometrial connexin 43 trafficking and gap junction assembly at term and in preterm labor
Authors: Hendrix E. M. , Mao S. J. T. , Everson W. , Larsen W. J. 
Published: February 2005

AbstractModulation of connexin 43 (cx43) in the myometrium of timed pregnant rats was studied using enzyme‐linked immunosorbent assay (ELISA), immunocytochemical localization, and immunoblot. These techniques utilized site‐specific antibodies directed against a portion of the carboxyl tail of cx43. We found that cx43 is synthesized several days prior to labor but accumulates within the cytoplasm until parturition, when it is rapidly transported to the plasma membrane and assembled into gap junction plaques at the cell surface. These cx43‐positive gap junctions begin to disappear from the plasma membrane within hours of delivery of the last pup and are completely absent within 24 hr following delivery. These structures are apparently internalized and degraded within the cytoplasm. ELISA documents a reduction of total cellular cx43 to baseline levels within 5 days following parturition. While the timing of synthesis, cytoplasmic storage, concentration in apparent Golgi vesicles, and transport to and assembly in the plasma membrane are accelerated in three models of preterm labor, the sequence of these events and the correlation of parturition with the formation of gap junctions are identical to those documented in normal labor. These results support the hypothesis that effective labor requires the synthesis and assembly of cx43 into functional gap junctions at the myometrial cell surface. © 1992 Wiley‐Liss, Inc.
F‐actin in guinea pig spermatozoa: Its role in calmodulin translocation during acrosome reaction
Authors: Moreno‐Fierros Leticia , Hernández Enrique Othon , Salgado Zaira O. , Mújica Adela 
Published: February 2005

AbstractThe presence of actin has been determined in mammalian spermatozoa. However, its function in these cells is still almost unknown. Only in boar spermatozoa has evidence for F‐actin and a possible function for it been presented. In this work, actin distribution and F‐actin were determined in uncapacitated, capacitated, and acrosomal‐reacted guinea pig spermatozoa, by means of monoclonal and polyclonal antibodies, using an indirect immunoperoxidase technique, and by the use of rhodamine‐phalloidin. With the last probe we found filamentous actin in these cells. By both techniques, actin was detected in the acrosome and in the entire tail. In some cells with acrosomal reaction, actin was also detected in the equatorial and in the postacrosomal regions. SDS‐PAGE and Western blots immunostained with monoclonal and polyclonal anti‐actin antibodies confirmed the presence of actin in extracts of guinea pig spermatozoa. Actin was also detected in preparations of Percoll‐purified spermatozoa. We have communicated that guinea pig spermatozoa show a change on calmodulin location during the acrosome reaction. They present it first in the equatorial region and later in the postacrosomal region. To determine if F‐actin participates in this calmodulin translocation, we studied the effect of cytochalasin D. It was found that the number of cells with calmodulin in the equatorial region increased in the presence of cytochalasin D while the number of cells with calmodulin in the postacrosomal region decreased. We also found that after cytochalasin D treatment acrosome loss was increased and sperm motility was slightly inhibited. Our results suggest that actin participate in calmodulin translocation to the postacrosomal region during acrosome reaction, in maintaining the acrosome structure, and perhaps also in sperm motility. © 1992 Wiley‐Liss, Inc.
A freezing and thawing method of hamster oocytes designed for both the penetration test and chromosome assay of human spermatozoa
Authors: Tateno Hiroyuki , Kamiguchi Yujiroh , Mikamo Kazuya 
Published: February 2005

AbstractSuperovulated hamster oocytes were cryopreserved and thawed according to our carefully designed procedures. More than 90% (92 ± 4%) of oocytes survived freezing and thawing. They were proven to be well conserved, showing excellent performance comparable to freshly ovulated oocytes in the human sperm penetration test (proportion of penetrated ova: 94.7% vs. 93.6%) and human sperm chromosome analysis (proportion of metaphasic ova: 81.8% vs. 83.6%). There was no statistically significant difference in the incidences of sperm chromosome aberrations between assays using fresh and frozen‐thawed oocytes. In addition, there was no statistically significant increase of aberrations in female pronuclear (hamster) chromosomes. This freezing‐thawing method was found to be reliable, yielding viable hamster oocytes of high quality. © 1992 Wiley‐Liss, Inc.
In vitro fertilization, development, and implantation after exposure of mature mouse oocytes to visible light
Authors: Barlow P. , Puissant F. , Van Der Zwalmen P. , Vandromme J. , Trigaux P. , Leroy F. 
Published: February 2005

AbstractMature mouse oocytes were exposed prior to in vitro fertilization to visible light during 1, 2, or 4 hr at an intensity of 4,000 lux. Compared to controls cultured under identical conditions but protected from light, exposed eggs did not show any significant modification of cleavage speed are rate. After transfer of blastocysts obtained in vitro in uteri of pseudopregnant females, the implantation rate and the proportion of normal fetuses were not found to be different in relation to preliminary light exposure of oocytes fertilized and cultured in vitro. © 1992 Wiley‐Liss, Inc.
Determination of enzyme activities of energy metabolism in the maturing rat oocyte
Authors: Tsutsumi Osamu , Satoh Kazuo , Taketani Yuji , Kato Takahiko 
Published: February 2005

AbstractEnzyme activities were determined quantitatively in individual rat oocytes to study their energy metabolism during maturation. Low hexokinase activity and high activities of lactate dehydrogenase and enzymes in the phosphate pathway, i.e., glucose 6‐P and 6‐P gluconate dehydrogenases, were characteristic of immature oocytes. Hexokinase may be a rate‐limiting enzyme that enables oocytes to use glucose as an energy source. During maturation, the activities of hexokinase, phospho‐fructokinase, and malate dehydrogenase increased significantly, suggesting that the glycolytic pathway, as well as the tricarboxylic acid cycle, developed as the first meiotic division proceeded. In contrast, the activities of glucose 6‐P and 6‐P gluconate dehydrogenases decreased in maturing oocytes. The observation that the enzyme pattern in mature oocytes resembles more closely that in somatic cells appears to be significant, especially in light of previous studies showing this developmental trend in preimplantation embryos. © 1992 Wiley‐Liss, Inc.
Isolation and cultivation of blastocyst‐derived stem cell lines from american mink (Mustela vison)
Authors: Sukoyan M. A. , Golubitsa A. N. , Zhelezova A. I. , Shilov A. G. , Vatolin S. Y. , Maximovsky L. P. , Andreeva L. E. , McWhir J. , Pack S. D. , Bayborodin S. I. , Kerkis A. Y. , Kizilova H. I. , Serov O. L. 
Published: February 2005

AbstractTen embryonic stem (ES) cell lines from mink blastocysts were isolated and characterized. All the lines had a normal diploid karyotype; of the ten lines studied, five had the XX and five had the XY constitution. Testing of the pluripotency of the ES‐like cells demonstrated that (1) among four lines of genotype XX, an X was late‐replicating in three; both Xs were active in about one‐third of cells of line MES8, and analysis of glucose‐6‐phosphate dehydrogenase revealed no dosage compensation for the X‐linked gene; (2) when cultured in suspension, the majority of lines were capable of forming “simple” embryoid bodies (EB), and two only showed the capacity for forming “cystic” multilayer EBs. However, formation of ectoderm or foci of yolk sac hematopoiesis, a feature of mouse ES ceils, was not observed in the “cystic” EB; (3) when cultured as a monolayer without feeder, the ES cells differentiated into either vimentin‐positive fibroblast‐like cells or cytokeratin‐positive epithelial‐like cells (less frequently); neural cells appeared in two lines; (4) when injected into athymic mice, only one of the four tested lines gave rise to tumors. These were fibrosarcomas composed of fibrobalst‐like cells, with an admixture of smooth muscular elements and stray islets of epithelial tissue; (5) when the ES cells of line MES1 were injected into 102 blastocyst cavities and subsequently transplanted into foster mathers, we obtained 30 offspring. Analysis of the biochemical markers and coat color did not demonstrate the presence of chimaeras among offspring. Thus the cell lines derived from mink blastocysts are true ES cells. However, their pluripotential capacities are restricted. © 1992 Wiley‐Liss, Inc.
Electrically induced calcium elevation, activation, and parthenogenetic development of bovine oocytes
Authors: Collas Philippe , Fissore Rafael , Robl James M. , Sullivan Eddie J. , Barnes Frank L. 
Published: February 2005

AbstractThe influence of electrical stimulation on the level of intracellular Ca2+ in bovine oocytes, as well as activation and extent of parthenogenetic development, was investigated. Mature oocytes were electrically stimulated at 29 hr of maturation, and intracellular Ca2+ concentration was determined with the Ca2+ indicator fura‐2 dextran (fura‐2 D). The Ca2+ response of oocytes to a given electrical pulse was variable. Oocytes responded with either no Ca2+ rise from baseline (≈︁ 12 nM), a short‐duration Ca2+ rise (from 12 nM to 300 nM) that returned to baseline within 2 min of the pulse, or a long‐duration Ca2+ rise (from 12 nM to 1,000–2,000 nM) that never returned to baseline during the 8 min period over which the oocytes were monitored. In these oocytes, Ca2+ level returned to baseline when oocytes were removed from 0.30 M mannitol and placed in an ionic medium. Increasing field strength or pulse duration tended to increase the proportion of oocytes displaying a Ca2+ rise, and at 1.0 kVcm−1 for 40 μsec, all oocytes displayed a long‐duration Ca2+ elevation. Direct transfer of oocytes from culture medium to mannitol also triggered a Ca2+ rise. Multiple stimulations, either electrical or by transferring to mannitol, produced multiple Ca2+ rises. This mannitol‐induced Ca2+ rise could be inhibited by first washing the oocytes in medium containing equal parts of 0.30 M mannitol and phosphate buffered saline (PBS). The level of Ca2+ stimulation affected activation and development of oocytes. Insufficient, or, conversely, excessive Ca2+ stimulation impaired development. Optimum development was obtained with (1) three pulses of 0.2 kVcm−1 for 20 μsec, each pulse 22 min apart, after direct transfer of oocytes from culture medium to mannitol (22% blastocysts) or (2) three pulses of 1.0 kVcm−1 for 20 μsec after transfer of oocytes from culture medium to medium containing equal parts mannitol and PBS, then to mannitol (24% blastocysts). This procedure avoided induction of a Ca2+ rise prior to the pulse. The results indicate that the level of Ca2+ stimulation can be regulated by incubation conditions prior to the pulse and, to some extent, by field strength and pulse duration. The level of electrical stimulation influenced oocyte Ca2+ response, activation, and parthenogenetic development. © 1993 Wiley‐Liss, Inc.
In vitro maturation of oocytes from a marsupial, the tammar wallaby (Macropus eugenii)
Authors: Mate Karen E. , Rodger John C. 
Published: February 2005

AbstractThis study examined the competence of oocytes from the tammar wallaby, Macropus eugeniio mature in vitro. Oocytes were collected from follicles >1 mm diameter 24 h after pregnant mare serum gonadotrophin (PMSG) treatment and incubated in Eagle's minimum essential medium supplemented with 10% fetal calf serum, at 35°C in 5% CO2 in air for 24, 36, or 48 h. Oocytes were incubated either granulosa cell‐intact or granulosa cell‐free or in the presence of 10 IU ml−1 PMSG or 10 μg ml−1 porcine luteinizing hormone (LH) + 10 μg ml−1 porcine follicle stimulating hormone (FSH). The ability of oocytes recovered from small (<1.5‐mm‐diameter) and large (≥1.5‐mm‐diameter) follicles to mature in vitro was also examined. The nuclear status of oocytes was assessed using the DNA‐specific dye Hoechst 33342. Initially, all oocytes examined contained a germinal vesicle. After 24 h of culture, 60% of oocytes had progressed to metaphase I or anaphase I. After 36 h, approximately 20% of oocytes possessed metaphase II chromosomes, and 20% of oocytes were at metaphase I or anaphase I. At the completion of the 48 h culture period, 40% of oocytes had completed maturation to the metaphase II stage. In vitro oocyte maturation after 48 h was not affected by the presence of granulosa cells, PMSG, or LH and FSH. More oocytes from large follicles (55%) completed maturation by 48 h than from small follicles (20%). Approximately 50% of oocytes remained at the GV stage at all times under all conditions. Marsupial oocytes thus undergo spontaneous nuclear maturation once removed from the follicular environment, suggesting a basically similar control system to that in placental mammals. © 1993 Wiley‐Liss, Inc.
Gene introduction into mouse blastocysts via “pricking”
Authors: Sato Masahiro , Tada Norihiro , Iwase Reiko , Amann Egon 
Published: February 2005

AbstractIt is a well‐known phenomenon that cultured mammalian cells that have been pricked in the presence of foreign DNA can be transformed. This micromanipulation ‘pricking’ technique was applied to mouse blastocysts to determine whether uptake of exogenous DNA would occur in the embryos. The middle region of the inner cell mass (ICM) was pricked three times in each blastocyst in a medium containing a linearized plasmid DNA. When the 60 treated blastocysts were transferred to the uterine horns of pseudopregnant females, 30 developing fetuses (50%) at the mid‐gestation stage were obtained. Twenty‐two of the 30 fetuses (73%) had less than 1 copy of the foreign DNA per diploid cell, as revealed by polymerase chain reaction (PCR)‐Southern analysis, a sensitive technique combined with Southern blot processing of the PCR products. The 8 other fetuses were negative for the foreign DNA. When blastocysts were pricked in the presence of vector DNA coupling E. coli β‐galactosidase (β‐gal) gene to a mouse metallothionein‐I (MT‐I) promoter and assessed for β‐gal activity histochemically after 1 and 5 days of culture in the presence of 1 μM CdCI2, at least 65% of the embryos exhibited β‐gal activity mainly in the ICM region. These results indicate that mouse blastocysts can be transfected with a relatively high efficiency after pricking, and that the introduced gene expression occurs. This approach provides a means of mapping the regulatory elements of genes that are active in the mouse blastocyst ICM, and may be useful in investigating the fate of the ICM cells in an intact blastocyst by labeling them via pricking technique. © 1993 Wiley‐Liss, Inc.
The protective action of betaine on the deleterious effects of NaCl on preimplantation mouse embryos in vitro
Authors: Biggers J. D. , Lawitts J. A. , Lechene C. P. 
Published: February 2005

AbstractThe development of outbred mouse (CF1) zygotes in vitro has been studied using medium SOM in which the concentrations of NaCl (85, 105, 125 mM), glutamine (0, 1, 2 mM), and betaine (0, 1, 2 mM) were varied. The effects of the compounds were studied using a 33 factorial experimental arrangement. The inhibitory effect of relatively high concentrations of NaCl and the protective effect of glutamine were confirmed. Betaine, an organic osmolyte, can also protect against the deleterious effects of relatively high concentrations of NaCl. The intracellular contents of potassium and sodium have also been measured in single zygotes using X‐ray electron probe spectrometry. When medium SOM contains 85 mM or 125 mM NaCl, the intracellular content of Na rises and the content of K decreases. These changes are partially reduced in the presence of 125 mM NaCl if betaine is also in the medium. Betaine has no effect on the intracellular content of K and Na if the concentration of NaCl is 85 mM. These results suggest that organic osmolytes may be required in embryo culture media to prevent excessive changes in the intracellular ionic concentration. © 1993 Wiley‐Liss, Inc.