bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential expression of insulin‐like growth factor‐II in specific regions of the late (post day 9.5) murine placenta
Authors: Redline Raymond W. , Chernicky Cheryl L. , Tan Hui‐Qing , Ilan Joseph , Ilan Judith 
Published: February 2005

AbstractInsulin‐like growth factor‐II (IGF‐II) expression has been implicated as a major determinant of fetal size during murine pregnancy. It remains unclear whether expression in the fetus, the placenta, or both is the overriding factor controlling growth. To gain further understanding of the placental contribution, we mapped IGF‐II expression in the fetal vascular and trophoblastic portions of the late murine placenta (day 9.5–18.5). We found that, as in the fetus itself, vasculogenic mesenchyme, in this case derived from the allantois, was the strongest expressor of IGF‐II. Trophoblast, on the other hand, while expressing somewhat less IGF‐II, showed a dynamic pattern of IGF‐II expression, which reflected its continuing differentiation during late pregnancy. Initially (days 9.5 and 12.5), the spongiotrophoblast, which is homologous to the cytotrophoblast columns and shell in early human pregnancy, strongly expressed IGF‐II. Later, expression in the spongiotrophoblast was down‐regulated as a new population, the 30‐called glycogen cells, emerged within the spongiotrophoblast (day 12.5–15.5) and went on to invade the mesometrial decidua. Glycogen cells, which are homologous to human intermediate trophoblast, strongly expressed IGF‐II. Trophoblast lining the area of maternalfetal exchange, the labyrinth, on the other hand, maintained a constitutive lower level of IGF‐II expression throughout late pregnancy. © 1993 Wiley‐Liss, Inc.
Anion channels in the sea urchin sperm plasma membrane
Authors: Morales Ezequiel , De La Torre Lucia , Moy Gary W. , Vacquier Victor D. , Darszon Alberto 
Published: February 2005

AbstractIonic fluxes in sea urchin sperm plasma membrane regulate cell motility and the acrosome reaction (AR). Although cationic channels mediate some of the ionic movements, little is known about anion channels in these cells. The fusion of sperm plasma membranes into lipid bilayers allowed identification of a 150 pS anion channel. This anion channel was enriched from detergent‐solubilized sperm plasma membranes using a wheat germ agglutinin Sepharose column. Vesicles formed from this preparation were fused into black lipid membranes (BLM), yielding single channel anion‐selective activity with the properties of those found in the sperm membranes. The following anion selectivity sequence was found: NO3− > CNS− > Br− > CI−. This anion channel has a high open probability at the holding potentials tested, it is partially blocked by 4,4′‐diisothiocyano‐2,2′ ‐stilbendisulfonic acid (DIDS), and it often displays substates. The sperm AR was also inhibited by DIDS. © 1993 Wiley‐Liss, Inc.
Surface‐associated glycosyltransferase activities in rat sertoli cells in vitro
Authors: Raychoudhury Samir S. , Millette Clarke F. 
Published: February 2005

AbstractWe have previously demonstrated fucosyltransferase (FT) activity on mouse germ cell surfaces at different stages of spermatogenesis. To complement these findings, here we report FT activity on the Sertoli cell (SC) surface. SC isolated and cultured from 20‐day‐old rat testes displayed FT activity with a Vmax of 12.5 pmoles/mg protein/min and a Km of 22 μM, while purified Sertoli cell plasma membranes (SCPM) showed FT activity with a Vmax of 10 pmoles/mg protein/min and a Km of 18.2 μM for GDP‐[14C]‐L‐fucose. Fucosyltransferase activities were 16.7 and 2.6 pmoles/mg protein/min in SC and SCPM, respectively; 16% of FT activity is, therefore, on the cell surface. To test whether the expression of FT activity in SC was regulated by hormones and growth factors, SC were cultured in serum‐free medium supplemented with insulin, transferrin, sodium selenite, and epidermal growth factor (medium 4F) or in 4F plus follicle‐stimulating hormone, testosterone, hydrocortisone, and vitamin E (medium 8F). We found that FT activity in SC is not modulated by these hormones or growth factors (4F or 8F). For comparison with FT, galactosyltransferase (GalTase) activities in SC and SCPM were also determined. SC displayed GalTase activity with a Vmax of 50 pmoles/mg protein/min and a Km of 38.5 μM, while SCPM showed GalTase activity with a Vmax of 25 pmoles/mg protein/min and a Km of 20.8 μM for UDP‐[3H]‐galactose. Galactosyltransferase activities were 29.2 and 9.6 pmoles/mg protein/min in SC and SCPM, respectively. Therefore, ∼33% of the total cell GalTase activity was detected on the surface membranes of rat Sertoli cells. These results suggest that cell surface glycosyltransferases may be involved in Sertoli cell function during mammalian spermatogenesis. © 1993 Wiley‐Liss, Inc.
Uptake and metabolism of pyruvate and glucose by individual sheep preattachment embryos developed in vivo
Authors: Gardner David K. , Lane Michelle , Batt Paul 
Published: February 2005

AbstractThe uptake of pyruvate and glucose by individual sheep oocytes and preattachment sheep embryos at each state of development up to the hatching blastocyst was determined using a microfluorescence technique. After an initial increase at fertilization, pyruvate uptake was relatively constant (˜15 pmol/embryo/h) from the zygote through to the morula. Upon blastocyst formation and hatching, there were significant increases in uptake (39 pmol/embryo/h, P < 0.001; and 53 pmol/embryo/h, P < 0.001, respectively). In contrast to that of pyruvate, glucose uptake was very low (˜1 pmol/embryo/h) up to the time of genome activation (eight‐ to 16 cell stage), after which there were significant increases in uptake at each successive stage of development. By the hatching blastocyst stage, glucose uptake had reached 54 pmol/embryo/h. The ability of day‐7 hatching blastocysts to oxidize pyruvate and glucose was determined indirectly by measuring the production of lactate when either substrate was present as the sole energy source. Unlike the mouse blastocyst, which has a considerable oxidative capacity for both pyruvate and glucose, the day‐7 sheep blastocyst showed limited ability to oxidise either substrate. Rather, in the sheep blastocyst, 65% of pyruvate and 98% of glucose taken up could be accounted for as lactate. Such low levels of substrate oxidation appear to be inconsistent with the energy requirements of the proliferating preattachment ruminant blastocyst. The utilization of alternative substrates at the blastocyst, such as amino acids, is proposed. © 1993 Wiley‐Liss, Inc.
Calcium channels play a pivotal role in the sequence of ionic changes involved in initiation of mouse sperm acrosomal exocytosis
Authors: Fraser Lynn R. 
Published: February 2005

AbstractThe sequence of ionic changes involved in initiation of acrosomal exocytosis in capacitated mouse spermatozoa was investigated. Earlier studies demonstrated that a large influx of Na+ is required for exocytosis, this Na+ apparently being associated with an increase in intracellular pH (pHi) via an Na+‐H+ exchanger. This rise in pHi may in turn activate calcium channels and permit the influx of extracellular Ca2+ needed to trigger acrosomal exocytosis. In the present study, the dihydropyridine voltage‐dependent calcium channel antagonist nifedipine was able to inhibit significantly exocytosis in sperm cells treated in various ways capable of stimulating acrosomal loss. The monovalent cation ionophore monensin can promote Na+ entry required for both capacitation and acrosomal exocytosis, as demonstrated by using chlortetracycline to monitor changes in sperm functional potential. In the presence of 10 nM nifedipine, monensin treatment accelerated capacitation but was unable to trigger exocytosis. The requirement for internalization of a high concentration of Na+ can be bypassed by the addition of 25 mM NH4CI to raise the pHi of cells capacitated in 25NH4CI to raise the pHi of cells capacitated in 25 mM Na+ (insufficient Na+ to support exocytosis under usual conditions). Again, introduction of nifedipine was able to inhibit exocytosis. In a third experimental approach, amiloridestimulated exocytosis in capacitated cells was significantly inhibited by nifedipine. In contrast to these treatments directed at specific mechanisms, the ability of the Ca2+ inophore A23187 to promote more general entry of Ca2+ and thereby to accelerate capacitation and exocytosis was not inhibited by nifedipine. Finally, monensin‐treated cells exhibited a rise and then a fall in 45Ca2+ uptake, the time course of which paralleled stimulation of acrosomal exocytosis in similarly treated cells. Nifedipine significantly reduced this uptake. The fact that nifedipine can block exocytosis induced by a variety treatments strongly suggests that voltage‐dependent calcium channels play a pivotal role in the response. These results are consistent with the following sequence of ionic changes in capacitated cells leading to acrosomal exocytosis: [Na+]i ↑ → [H]i↓ → pHi ↑ → activation of calcium channels → [Ca2+]i ↑ → exocytosis. Given that zona‐induced exocytosis is reportedly an indirect response, mediated by voltage‐dependent calcium channels, and that the Na+‐H+ exchanger in somatic cells can be activated by receptor‐mediated mechanisms, we suggest that sperm‐zona inter action promotes an influx of Na+ by activating an Na+‐H+ exchanger and thereby initiating the above sequence of changes. © 1993 Wiley‐Liss, Inc.
Porcine zona pellucida ZP3α glycoprotein mediates binding of the biotin‐labeled Mr 55,000 family (ZP3) to boar sperm membrane vesicles
Authors: Yurewicz Edward C. , Pack Beverley A. , Armant D. Randall , Sacco Anthony G. 
Published: February 2005

AbstractThe two Mr 55,000 glycoproteins, ZP3α and ZP3b̃, of porcine zona pellucida copurify as a preparation designated ZP3. Gamete binding assays have implicated ZP3α, but not ZP3b̃, as participating in sperm‐zona recognition events. We now report that boar sperm contain membrane‐associated binding sites with specificity for ZP3α. Biotin‐labeled (b‐) preparations of ZP3 bind to intact boar sperm in a saturable manner, with localization on the anterior head region. Membrane vesicles obtained from capacitated sperm by nitrogen cavitation retain b‐ZP3 binding sites as determined by an enzyme‐linked method employing alkaline phosphatase‐conjugated strepavidin. In competitive binding assays using b‐ZP3 (0.1μg/ml) as probe, heat‐solubilized zonae and ZP3 were effective competitors, whereas the nonzona molecules fetuin and fucoidin were not. Digestion of ZP3 with endo‐b̃‐galactosidase, an enzyme that trims polylactosamines, enhanced its affinity for membrane receptors. In contrast treatments such as chemical deglycosylation, pronase digestion, or disruption of disulfide bonds abolished the ligand activity of ZP3. Finally, purified ZP3α was an at least 100‐fold better antagonist than purified ZP3b̃. The results demonstrate that binding of b‐ZP3 to isolated boar sperm membranes is mediated by sperm receptors with specificity for the ZP3α macromolecular component and reveal a complex contribution of both carbohydrate and protein moieties toward the ligand activity of this sperm adhesive zona molecule. © 1993 Wiley‐Liss, Inc.
Sequence, expression, and chromosomal assignment of a human sperm outer dense fiber gene
Authors: Gastmann Oliver , Burfeind Peter , Güunther Eberhard , Hameister Horst , Szpirer Claude , Hoyer‐Fender Sigrid 
Published: February 2005

AbstractOuter dense fibers (ODFs) are located on the outside of the axoneme in the midpiece and principal piece of the mammalian sperm tail and may help to maintain the passive elastic structures and elastic recoil of the sperm tail. We have identified and describe here a human gene that is homologous to the Mst(3)CGP gene family of Drosophila melanogaster and encodes an ODF protein of 241 amino acids. The transcribed region has a size of ˜lkb and contains two exons of 416 bp and 406 bp, respectively, not including the 3′ untranslated region. The gene is expressed in testis but not in human spleen, kidney, or brain and resembles in this respect the expression of the Drosophila Mst(3)CGP gene family in the male germline. An antiserum raised against a synthetic peptide derived from the N‐terminus of the encoded sequence identified a protein of ˜ 32 kDa in an extract of human sperm flagella. By Southern‐blot analyses and in situ hybridization, the ODF gene was localized to band q22 of chromosome 8. The isolation of a human gene encoding a sperm tail protein may provide the ability to identify and investigate, on the molecular level, possible reasons for human male infertility that are dependent on flagellar disturbances. © 1993 Wiley‐Liss, Inc.
Zinc, iron, and copper contents of Xenopus laevis oocytes and embryos
Authors: Nomizu Tsutomu , Falchuk Kenneth H. , Vallee Bert L. 
Published: February 2005

AbstractZinc is essential for vertebrate development; its deficiency results in multiple congenital malformations. Knowledge of the zinc biochemistry that underlies embryologic development is very limited. This has led us to investigate the zinc, iron, and copper contents of Xenopus laevis oocytes and embryos. Stage 1–6 oocytes, isolated from ovaries, and stage 1–40 embryos, obtained by in vitro fertilization techniques, were washed in metalfree water prior to digestion by 70% ultrapure HNO3. The metal content of the digests was analyzed by atomic absorption spectrometry. Stage 6 oocytes contain 65.8 4, 31.1 ± 3, and 0.68 ± 0.2 ng of zinc, iron and copper, respectively. The corresponding concentrations are 1, 0.5, and 0.01 mM in 1 μl eggs. The metal content varies as a function of egg maturation. The zinc content increases from 3–7 to >60 ng by stages 3 and 6, respectively. A similar pattern is noted for iron, which increases from 2–5 to 30 ng at analogous stages. In contrast, the copper content remains virtually unchanged in oocytes undergoing maturation. Importantly, the total of all three metals does not vary throughout the first 50 stages of development, when all tadpole organs are forming. Hence, the full complement of zinc, iron, and copper needed for incorporation into apoproteins during development is already present at a time when oocyte maturation is completed. The specific metalloproteins that store, donate, and accept these metals during induction and organogenesis and the alterations caused by metal deficiency can now be identified. © 1993 Wiley‐Liss, Inc.
Mitogenic and cytogenetic evaluation of transforming growth factor‐β on murine preimplantation embryonic development in vitro
Authors: Lim Joyce , Bongso Ariff , Ratnam Shan 
Published: February 2005

AbstractSlow cleavage rate has been a major contributory factor influencing embryo morphology in in vitro fertilization (IVF) programs. The role of transforming growth factor‐b̃ (TGFb̃1) in improving this characteristic was evaluated using the murine model. Replicate batches of eight‐cell compacting embryos from superovulated mice were divided into three groups. Group A were treated with 0.3 ng/ml TGFb̃1 at the initial compacting stage, followed by a second treatment of 0.1 ng/mL 22 h later at the cavitating stage; group B received 0.3 ng/ml TGFb̃1 at the cavitating stage; group C were controls. The percentages of treated embryos reaching fixed embryonic stages, total cell number (TCN), mitotic index, and incidence of chromosome anomalies were monitored. The percentage of embryos reaching the cavitating, expanded, hatching, and hatched stages in both treatment groups were not significantly different from control (96.6% ± 4.2% to 37.7% ± 12.7% vs. 95.3% ± 7.3% to 47.0% ± 3.5%; P > 0.05). Values between the two treatment groups were also not significantly different. Embryos in groups A and B produced significantly greater TCN at expanded blastocyst and hatching stages compared to controls (Group A: 107.0 ± 18.9 vs. 89.9 ± 17.4, P < 0.05 and 125.5 ± 16.4 vs. 113.9 ± 12.1, P < 0.05; Group B: 107.9 ± 14.0 vs. 89.9 ± 17.4, P < 0.05 and 124.9 ± 17.4 vs. 113.9 ± 12.1, P < 0.05). Values, however, were not significantly different between treatment groups. The mean mitotic index for eight‐cell compacting embryos treated with a single dose of 0.3 ng/ml TGFb̃1 was significantly greater than control (0.1944 ± 0.1376 vs. 0.1282 ± 0.2573, P < 0.05). No significant increase in the incidence of chromosome anomalies was observed in embryos exposed to TGFb̃1. The results demonstrate that TGFb̃1 had a tremendous mitogenic effect on late murine embryonic stages and may thus be useful to improve embryo morphology in IVF programs and to produce adequate metaphases from biopsied embryos for preimplantation cytogenetic diagnosis. © 1993 Wiley‐Liss, Inc.
Effect of follicle size on bovine oocyte quality and developmental competence following maturation, fertilization, and culture in vitro
Authors: Lonergan P. , Monaghan P. , Rizos D. , Boland M. P. , Gordon I. 
Published: February 2005

AbstractThe aim of the present series of experiments was to investigate the effect of the size of follicle from which the oocytes originate on their subsequent in vitro developmental ability. Ovarian follicles were isolated and grouped according to size (2–6 mm, >6 mm). Primary oocytes were carefully liberated and grouped according to morphology into one of five categories: denuded; expanded; with two or three layers of cumulus; with four or five layers; and with many (six or more) layers. Following in vitro maturation (IVM), fertilization (IVF), and culture (IVC), more oocytes with many layers of cumulus (P < 0.01, 70.2%, 73/104 vs. 46.8%, 87/186, respectively) and a higher proportion of blastocysts were obtained from follicles > 6 mm compared to 2–6 mm follicles (P < 0.01, 65.9%, 60/91 from >6 mm follicles vs. 34.3%, 34/99 from 2–6 mm follicles, respectively). Use of follicular fluid (BFF) from follicles of different sizes in the IVM medium did not significantly increase the cleavage rate or blastocyst yield compared to controls. Administration of procine folliclestimulating hormone (pFSH) to donors prior to slaughter was investigated as a possible means of increasing the number of larger sized follicles in the ovaries and, thereby, the quality of the recovered oocytes. It was found that administration of six injections of pFSH beginning 3 days prior to slaughter resulted in a significant increase (P < 0.001) in the proportion of follicles >6 mm in diameter (31.6%) compared to that in nontreated controls (6.6%) and to animals that received only four injection groups (9.4%). The blastocyst yield from oocytes originating from >6 mm follicles, whether from unstimulated or from pFSH‐treated animals, was approximately double that of oocytes from 2–6 mm follicles (P < 0.01; 42.9%, 24/56 for >6 mm follicles vs. 22.8%, 21/92 for 2–6 mm follicles, respectively, for the 6 pFSH group; P > 0.05; 62.5%, 5/8 for >6 mm follicles vs. 32.8%, 22/67 for 2–6 mm follicles, respectively, for the control). © 1994 Wiley‐Liss, Inc.
Nuclear dynamics of parthenogenesis of bovine oocytes matured in vitro for 20 and 40 hours and activated with combined ethanol and cycloheximide treatment
Authors: Presicce Giorgio A. , Yang Xiangzhong 
Published: February 2005

AbstractBovine oocytes matured in vitro (IVM) for 20 hr vs. 40 hr were treated for activation with 7% ethanol in Dulbecco's phosphate‐buffered saline for 5 min followed by incubation in M199 + 7.5% fetal calf serum containing cycloheximide (10 μg/ml). TreatedIVM oocytes and the controls (no ethanol and cycloheximide exposures) were fixed after 0, 1, 2, 3, 4, 5, 7, 10, and 20 hr of incubation and stained 24 hr later with 1% acetoorcein to examine nuclear events. Different stages of nuclear development of the activated oocytes were identified on the basis of nuclear and chromosomal morphology. Pronuclear development was classified into four stages (PN I, II, III, and IV) according to pronuclear progression in chromatin decondensation, nucleoplasm appearance, and nuclear size. The results demonstrated that the combined activation treatment effectively drove the IVM oocytes, both young (20 hr) and aging (40 hr), out of metaphase arrest. The activation rates for young oocytes examined immediately after 0, 1, 2, 3, 4, 5, 7, 10, and 20 hr of incubation with cycloheximide were, respectively, 7%, 24%, 77%, 96%, 92%, 97%, 98%, 93%, and 98%. For aging oocytes (40 hr) the corresponding activation values at the same time intervals were 6%, 84%, 100%, 100%, 100%, 100%, 98%, 100%, and 100%, respectively. These values were significantly higher than those for the corresponding controls. The activated aging oocytes achieved peak activation response more rapidly than did young oocytes. In addition, nuclear events in aging oocytes proceeded faster than those in young ones. Spontaneous activation rates of the aging oocytes were also higher (6–57%) than those of the young ones (0–14%). © 1994 Wiley‐Liss, Inc.
Deficiency in fertilization by morphologically abnormal sperm produced by Azh mutant mice
Authors: Meistrich Marvin L. , Kasai Kenichi , Olds‐Clarke Patricia , Macgregor Grant R. , Berkowitz Albert D. , Tung Kenneth S. K. 
Published: February 2005

AbstractMale mice homozygous for the azh mutation produce spermatozoa with abnormal head shapes and have significantly reduced fecundity, to between 5% and 10% that of wild‐type or heterozygous mice. Several possible causes of this infertility were investigated. No gross endocrine disorders in azh/azh male mice were observed, and they exhibited apparently normal mating behavior. In addition, their sperm were motile, were capable of hyperactivated motility, and did not show premature acrosome reactions. However, quantitative analysis revealed slight but significant reductions in several motility parameters. Analysis of embryos following mating of azh/azh males with superovulated females indicated a reduction in the number of fertilized eggs compared to control matings. In vitro, spermatozoa from azh/azh mice failed to fertilize cumulus‐intact/zona‐intact and cumulus‐free/zona‐intact ova, although they successfully fertilized zonafree ova. These results indicate that the primary defect in fertility of azh/azh male mice is a result of sperm quality, likely, in sperm morphology, and is manifest at the level of interaction with the zona pellucida. © 1994 Wiley‐Liss, Inc.
Unusual nuclear structure of the spermatozoon in a marsupial, Sminthopsis crassicaudata
Authors: Breed W. G. , Leigh C. M. , Washington J. M. , Soon L. L. L. 
Published: February 2005

AbstractThe organization of sperm chromatin in the dasyurid marsupial, Sminthopsis crassicaudata, was investigated using various morphological techniques. Transmission electron microscopy indicates two quite distinct chromatin regions became evident late in spermiogenesis with an outer globular region containing blocks of very electron‐dense chromatin. Fluorescent light microscopical studies after staining with DNA dyes and 7‐amino actinomycin D of testicular, caput, and cauda epididymal spermatozoa showed that this region fluoresced less brightly than the rest of the nucleus, indicating the presence of fewer DNA binding sites. Freeze fracture showed that the chromatin in most of the nucleus had randomly arranged particles of various sizes, but that of the outer region was composed entirely of small particles. This outer region was more resistant to low concentrations of the ionic detergent, SDS, whereas both guanidine hydrochloride and urea together with sodium chloride generally dispersed all the chromatin except that in the outer globular region and in a localized area of the nucleus beneath the acrosome. This study has thus revealed that the outer globular chromatin of these spermatozoa responds differently to ionic detergents and protein denaturing agents and has a different chromatin organization than most of the rest of the nucleus. The significance of these differences remains, however, to be determined. © 1994 Wiley‐Liss, Inc.