bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amino acid transport and exchange in unfertilized mouse eggs
Authors: Miller J. G. O. , Schultz G. A. 
Published: February 2005

AbstractThe mouse egg is an ideal model for the kinetic study of neutral amino acid exchange transport in development in that it possesses strong exchange‐mediated uptake/efflux with little other efflux. Exchange transport was examined by preloading eggs in unlabeled or labeled amino acid and then measuring subsequent amino acid fluxes. The existence of two L‐like (leucine‐preferring) systems, a low‐affinity exchange system, and a high‐affinity weakly exchanging system is suggested by the differences between preloaded and control eggs in uptake specificity and in the kinetic parameters of methionine uptake (respectively, Km = 220 and 69 μM, Vmax = 98 and 32 fmol/min/egg). The Vmax of exchange‐mediated efflux of methionine is similar to that for uptake into preloaded eggs, but the Km is about an order of magnitude higher. Preloading in alanine and serine (preferred substrates, along with cysteine, of system ASC) decreased the subsequent uptake of radiolabeled methionine, suggesting some ASC activity in the unfertilized mouse egg. The plateau in accumulation of leucine and phenylalanine, characteristic of simple exchange (mediated by system L), is not shared by methionine, suggesting the existence of another system (possibly an A, or alanine‐preferring, system) for the transport of methionine. Amino acid transport in the mouse egg is more complex than previously thought, the egg possessing four interacting systems for the transport of the neutral amino acids.
Effect of sperm motility on human embryo quality in in vitro fertilization
Authors: Chye Ng Soon , Edirisinghe W. R. , Wong P. C. , Ratnam S. S. 
Published: February 2005

AbstractSperm motility is important for penetration of the zona pellucida, and this parameter has been reported to be the single most important factor determining fertilization rates. As there was no report on the relationship between sperm motility and embryo quality, we investigated the influence of sperm motility on embryo quality in 41 patients with tubal disease and/or obstruction. The patients were either unstimulated or stimulated with clomiphene or clomiphene and human menopausal gonadotrophin. Of 116 oocytes collected, 86 (74.1%) fertilised and cleaved; of these only 44 embryos had clear equal blastomeres without fragmentation (grade 3). Grade 3 embryos were equally distributed through all initial sperm motility categories, and through all categories of sperm concentration after swim‐up. The ratio of motile sperm concentration in the initial semen sample to the final sperm concentration after swim‐up varied from 0.5 to 67, and grade 3 embryos were distributed randomly from low to high ratios. The pregnancy rate in this series was only 14.6% per replacement. The rate of gestational sacs per embryo replaced was 7.0% (6/86); if “poor” embryos were excluded, the rate was 9.1% (6/66). The absence of correlation between sperm motility and embryo quality is discussed on morphological grounds.
Action of phosphatidylcholine in protecting ram sperm from cold shock
Authors: Simpson Ann M. , Swan M. A. , White I. G. 
Published: February 2005

AbstractRapid cooling (cold shocking) of washed ejaculated ram sperm to 0°C irreversibly reduced motility, tail beat frequency, and respiration and increased the uptake of 45Ca2+. The plasma membranes were removed from the sperm head, and the acrosomes were detached from the nuclei. The plasma membranes of the middle piece were removed, and the mitochondria contained pale and expanded cristae, similar in appearance to ATP‐deprived mitochondria in the “condensed” configuration. The presence of 2.0 mg/ml phosphatidylcholine (lecithin) in the medium prevented ultrastructural damage on cold shock, and the motility, tail beat frequency, respiratory rate, and calcium uptake were maintained at levels similar to washed sperm. As the “protective” effect of phosphatidylcholine against cold shock was maintained to a certain extent after rewashing and centrifuging the sperm prior to cold shock, the interaction of phosphatidylcholine with ram sperm membranes may be fairly “tight” and not easily disrupted.
Vital staining and acrosomal evaluation of bovine sperm
Authors: Aalseth E. P. , Saacke R. G. 
Published: February 2005

AbstractDried smears prepared from vitally stained sperm were evaluated as a method of simultaneously determining sperm viability and acrosomal morphology. A combination Fast Green FCF‐Eosin B stain was used. The stained smears were examined at × 1, 250 using differential interference contrast microscopy (DIC). For comparison, the percentage of sperm with intact acrosomes was also determined from wet smears using DIC. Acrosomal morphology was not altered by the staining procedure, as the percentage of intact acrosomes was similar whether quantitated from wet or stained smears. Absence of eosinophilic staining in the acrosome was used as an indication of sperm viability. The percentage of sperm with unstained acrosomes was highly correlated with the percentage of intact acrosomes quantitated from stained smears. Thus, vital staining provided an indication of sperm viability comparable to acrosomal integrity, a highly reliable technique. The major advantages of using dried stained smears were more thorough examination of individual sperm without sperm activity interference, simultaneous evidence of sperm viability and morphology, and the opportunity to delay evaluation. In addition, diluting spermatozoa in complex or simple media with or without egg yolk or follicular fluid did not interfere with subsequent staining or acrosomal evaluation.
Hormonal dissociation of ovulation and maturation of oocytes: Ovulation of immature amphibian oocytes by prostaglandin
Authors: Schuetz Allen W. 
Published: February 2005

AbstractProstaglandin involvement in ovulation and maturation of amphibian (Rana pipiens) ovarian follicular oocytes was investigated using in vitro‐cultured ovarian follicles. Exposure of follicles to PGF2α during culture stimulated variable but generally low levels of ovulation without concomitant induction of maturation. Addition of PGF2α to cultured follicles markedly enhanced the incidence of ovulation in follicles exposed to progesterone or frog pituitary homogenate (FPH). Onset of the ovulatory process was further accelerated following addition of PGF2α to FPH‐treated follicles. PGE, in contrast to PGF2α, exhibited no stimulatory effects on ovulation and consistently inhibited ovulation induction by FPH and progesterone. Cytological analysis of follicles undergoing ovulation revealed that ovulation of immature oocytes induced by PGF2α varied markedly from that seen following FPH or progesterone stimulation of follicles in vivo or in vitro. Immature oocytes in contrast to maturing oocytes were typically ovlulated with follicle cells still attached to the vitelline membrane. The observations indicate that PGF2α effected follicle rupture and contraction of the follicular epithelium and theca without prior separation of the follicle cells from the oocyte. Selective inhibitors of steroid synthesis (cyanoketone) and protein synthesis (cycloheximide) inhibited FPH‐induced ovulation and maturation. PGF2α reversed the inhibitory effects of cyanoketone and cycloheximide on FPH‐induced ovulation but not maturation of oocytes. Neither prostaglandins alone or in combination with progesterone or FPH induced ovulation of oocytes following removal of the follicular epithelium. Ovulatory effects of PGF2α appear to be mediated through the follicular epithelium. Results indicate that ovulation and maturation of amphibian oocytes can be induced independently of each other by separate classes of hormones. Normal synchronization of ovulation and maturation of oocytes may require the combined action of prostaglandins and steroids acting within different follicular compartments.
Fertilization cones of inseminated sea urchin (Arbacia punctulata) oocytes: Development of an asymmetry in plasma membrane topography
Authors: Longo Frank J. 
Published: February 2005

AbstractElectron microscopic and cytochemical investigations were carried out on inseminated Arbacia oocytes comparing structural and chemical properties of their microvillous surface and fertilization cones. Early fertilization cones (up to 4 min postinsemination) were relatively small, smooth surface projections of cytoplasm that engulfed the incorporated sperm nucleus. However, in contrast to surrounding microvillous areas of the oocyte surface, enlarged fertilization cones (8 to 15 min postinsemination) had a distinctive crenated appearance that persisted until their regression. When examined by various cytochemical techniques, membrane delimiting fertilization cones had a much lower affinity for agents that stain negatively charged and carbohydrate moieties (cationized ferritin, concanavalin A, ruthenium red, and alcian blue) than did other regions of the oocyte surface. This difference in surface properties of membrane delimiting the site of sperm‐egg fusion was not due solely to incorporated sperm plasma membrane and did not occur when inseminated oocytes were incubated with cytochalasin B. Little or no difference in the membrane of the fertilization cone versus microvillous areas was observed when inseminated eggs were freeze‐fractured or prepared with agents (filipin and polymixin B) to demonstrate β‐hydroxysterols and anionic phospholipids. These observations indicate that membrane delimiting the fertilization cone differs from the remainder of the oocyte surface and suggests that following insemination significant rearrangements of surface molecules take place within the egg plasmalemma that give rise to asymmetries in membrane topography.
X‐Y chromosome univalency in the testes of hyperthermic mice: I. Concomitant formation of multinucleated giant cells
Authors: Waldbieser G. C. , Chrisman C. L. 
Published: February 2005

AbstractExposure of mice to an environment of approximately 35°C and 65% relative humidity for 2–5 days caused dissociation of the X‐Y chromosome bivalent in diakinesis‐metaphase I (primary) spermatocytes. Dissociation of autosomal bivalents, chromosome fragmentation, aneuploidy, and polyploidy were not significantly affected by heat stress. Heat stress also caused formation of multinucleated giant cells in the mouse testis. Giant cell formation followed a distribution similar to X‐Y dissociation, reaching highest levels 5 days after heat stress and returning to control levels 50–70 days after heat stress. Spermatogonial activity was not permanently damaged by these conditions, and the germinal epithelium was able to repopulate. We believe that cell aberration or cell death resulting from either or both of these anomalies causes much of the decreased fertility found after subjecting scrotal mammals to high temperatures.
Partial purification and characterization of dipeptidyl peptidase II (DPP II) from guinea pig testes
Authors: DiCarlantonio G. , Talbot P. , Dudenhausen Elizabeth 
Published: February 2005

AbstractDepeptidyl peptidase (DPP II) was partially purified from guinea pig testes by (NH4)2SO4 precipitation, Con A‐Sepharose 4B chromatography, and Sephadex G‐200 chromatography to a specific activity of 27.4 μmol Ala3 hydrolyzed min−1 mg−1 protein. Chromatography on a calibrated G‐200 column yielded a molecular weight of 135,000 daltons for the enzyme. Sodium dodecyl sulfate polyacrylamide electrophoresis showed an enrichment of a broad doublet at 64–66,000 daltons. The enzyme had optimal activity toward hydrolysis of L‐alanyl‐alanyl‐alanine at pH 4.5 and showed sensitivity to cations of increasing size with Tris producing the most inhibition of those tested. The enzyme was moderately inhibited by serine proteinase inhibitors. Thin‐layer chromatography revealed the dipeptidase nature of the enzyme's activity on tripeptides and dipeptidyl arylamides. A doublet of activity occurred when nitrocellulose electroblots of nondenaturing gel electrophoresis of the (NH4)2SO4 fraction were reacted with the specific DPP II substrate, lysyl‐alanyl‐4‐methoxy‐2‐napthylamide. Analytical isoelectric focusing of the G‐200 fraction followed by fluorescent enzyme activity detection that used cellulose triacetate overlay membranes impregnated with the specific DPP II substrate, lysyl‐alanyl‐7‐amino‐4‐trifluoromethylcou‐marin, revealed multiple isoforms focusing at pI = 4.8–5.6. Two prominent bands focused at pI = 4.9 and pI = 5.1. The properties of guinea pig testicular DPP II are compared and contrasted with similar dipeptidyl peptidases from other sources.
Sperm‐oocyte membrane fusion in the human during monospermic fertilization
Authors: Sathananthan A. Henry , Chen Christopher 
Published: February 2005

AbstractSperm‐oocyte membrane fusion has been observed during monospermic fertilization of a human oocyte in vitro.Women were stimulated with both clomiphene citrate and human menopausal gonadotropin and were given human chorionic gonadotropin before a LH‐surge. Twelve oocytes, collected at laparoscopy from six women who became pregnant by IVF, were allowed to mature for 7–14 hours in vitro and inseminated with preincubated sperm, fixed between 1–3 hours after insemination, and examined by transmission electron microscopy.Membrane fusion had occurred in one ovum 2 hours after insemination, and the oocyte had resumed maturation and was at anaphase II of meiosis. Cortical granules had been exocytosed, and some of their contents were visible at the surface close to the oolemma all around the oocyte. The sperm that fused with this oocyte was acrosome‐reacted and had been partly incorporated into the ooplasm, while the anterior two‐thirds of its head was phagocytosed by a tongue of cortical ooplasm. Membrane fusion had occurred between the oolemma and the plasma membrane overlying the postacrosomal segment of the sperm head, posterior to the equatorial vestige. Sperm chromatin had not decondensed, and serial sections revealed a midpiece attached to the basal plate and a tail located deeper in the ooplasm, all devoid of plasma membrane. Supplementary sperm penetrating the inner zona, approaching the perivitelline space, had undergone the acrosome reaction but had a persistent vestige of the equatorial segment of the acrosome with intact plasma membrane. Evidence of sperm chromatin decondensation was seen in other oocytes, 3 hours after insemination, which were at telophase II of meiosis. Eight oocytes penetrated by sperm were monospermic, while four were unfertilized.The general pattern of sperm fusion and incorporation appears to conform to that seen in most other mammals. The study also reveals that sperm have to complete the acrosome reaction before fusing with the egg.
X‐Y chromosome univalency in the testes of hyperthermic mice: II. Light and electron microscopic analysis of synaptonemal complexes
Authors: Waldbieser G. C. , Chrisman C. L. 
Published: February 2005

AbstractHyperthermia‐induced X‐Y dissociation has been observed in diakinesis‐metaphase I sper‐matocytes but not in pachytene spermatocytes, which have been implicated as highly susceptible to heat stress. To determine X‐Y dissociation in pachytene spermatocytes and to compare levels of dissociation between pachytene and diakinesis‐metaphase I spermatocytes male ICR mice were exposed to 35°C ± 0.07°C and 65% ± 0.14% relative humidity for 2 or 4 days. Control mice were housed at 24°C ± 0.04°C and 43% ± 0.58% relative humidity. Mice were killed 0, 3, 5, 8, or 10 days after stress and the testes processed for meiotic chromosome display at diakinesis‐metaphase I and synaptonemal complex display at pachynema. Twenty‐five to thirty cells per mouse at both stages of meiosis were observed with light microscopy, and pachytene spreads with transmission electron microscopy to determine heat‐stress effects on synaptonemal complex structure. Statistical analyses revealed significant linear increases in X‐Y dissociation with prolonged exposure to heat at pachynema and diakinesis‐metaphase I. Levels of pachytene dissociation were one‐half the levels of dissociation at diakinesis‐metaphase I. The resolvable structure of the lateral elements of the synaptonemal complex was not affected by heat stress.
Human sperm chromosomes in zona‐free hamster eggs: Pretreatment of spermatozoa with calcium ionophore facilitates later examination of chromosomes
Authors: Wramsby H. , Yanagimachi R. 
Published: February 2005

AbstractFreshly ejaculated human spermatozoa exposed to 10 μM calcium ionophore A23187 for 30 minutes quickly bound to and penetrated into zona‐free hamster eggs. When these eggs were cultured for 13 hours in the presence of low concentrations of vinblastin and podophyllotoxin, then fixed and spread with the use of a cold fixation technique, haploid sets of sperm chromosomes were demonstrated. The number of spermatozoa that were attached to the egg surface at insemination influenced the success rate of chromosome demonstration. The best results (an average of about 0.7 chromosome set per egg) were obtained when insemination was controlled so that an average of seven spermatozoa attached to each egg at the end of a 15–30‐minute insemination period. This improved method for demonstrating human sperm chromosomes would be useful in the analysis of paternal genetic contributions in reproduction as well as in assessing the effects of environmental genotoxic agents or conditions on spermatozoa.
Action of gossypol on rat germinal cells. II. The acrosome
Authors: Baccetti B. , Bigliardi E. , Burrini A. G. , Renieri T. , Selmi M. G. 
Published: February 2005

AbstractThe action of gossypol on the acrosomal complex in rats has been investigated by microscopical and submicroscopical methods. The drug displays its morphological action only on spermatozoa during the transit through the epididymis, causing malformations and vesiculations. It appears to exert a primary action on the SS groups formation, disturbing morphological molding occurring in this period and inhibiting capacitation.
Interactions of aged gametes: In vitro fertilization using in vitro‐aged sperm and in vivo‐aged ova in the mouse
Authors: Smith A. L. , Lodge J. R. 
Published: February 2005

AbstractA study of varying combinations of in vitro‐aged sperm and in vivo‐aged ova at 3 hr intervals from 0–24 hr resulted in failures at different steps of the fertilization process during in vitro fertilization of mouse ova. Significant decreases caused by sperm aging, ova aging, and sperm × ova aging interaction were found in sperm penetration. Pronuclear formation was not affected by sperm aging and was enhanced by ova aging, and there was a significant effect of sperm × ova aging interaction. Sperm aging significantly influenced the prometaphase stage of the fertilization process. Therefore, it is suggested that the detrimental fertilization effects resulting from aging gametes are due to different mechanisms in sperm and ova, that these mechanisms are affected at different times, and that they affect different steps in the fertilization process.
Cyclic nucleotide content and protein phosphorylation during maturation of Spisula oocytes
Authors: Adeyemo Oyewole , Shirai Hiroko , Koide S. S. 
Published: February 2005

AbstractCyclic nucleotide levels in the oocytes of the surf clam Spisula solidissima were measured during germinal vesicle breakdown (GVBD) induced by fertilization. The level of cAMP and cGMP in untreated oocytes was 8.23 ± 0.95 and 4.89 ± 0.39 pmol/106 oocytes. The ratio of cAMP to cGMP ranged from 1.5 to 2.0. The cAMP level in Spisula oocytes fluctuated after fertilization and before GVBD. The cGMP level showed minimal fluctuation, with a tendency to decrease initially followed by a subsequent rise to the basal level in a nonsynchronous manner. These changes were not statistically significant. There was a general increase in protein phosphorylation during the period after fertilization and before GVBD. The greatest increase occurred with proteins of estimated molecular weights of 52, 18, and 12 kD, analyzed by gel electrophoresis and autoradiography.
Superovulation in immature and mature Chinese hamsters
Authors: Roldan Eduardo R. S. , Horiuchi Toshitaka , Yanagimachi Ryuzo 
Published: February 2005

AbstractMature female Chinese hamsters ovulate an average of 8.8 ± 1.0 (mean ± SD) eggs per female in each estrous cycle. Superovulation can be induced in both immature and mature females by subcutaneous or intraperitoneal injections of pregnant mare serum gonadotropin (PMSG) and either human chorionic gonadotropin (hCG) or pituitary luteinizing hormone (PLH). The best superovulation in immature females was induced by the administration of 15 IU of PMSG followed 72 hr later by injection of 15 IU of hCG (about 25 eggs per female) or 0.2 mg (200 IU) PLH (about 46 eggs per female). Ovulation started about 13–15 hr after administration of hCG (or PLH) and was completed during the next 5–6 hr. Superovulation in mature females could be induced by injecting PMSG any day of the estrous cycle, but the best superovulation (about 39 eggs per female) was induced by injecting 15 IU of PMSG on day 1 (day of ovulation) followed by the injection of 0.4 mg of PLH 72 hr later. When immature females treated with the best superovulatory protocol were mated on the evening of PLH injection, only 5% of the eggs were found fertilized 50 hr after PLH administration. On the other hand, about 60% of the eggs were found fertilized in mature females mated following treatment with the best superovulatory protocol. The majority (83–85%) of superovulated eggs obtained from both immature and mature females were normally fertilized in vitro.
Isolation of 125I‐concanavalin A‐labeled plasma membrane from unfertilized mouse eggs
Authors: Boldt Jeffrey , Wolf Don P. 
Published: February 2005

AbstractA procedure was developed for isolation of plasma membrane (PM) preparations from unfertilized mouse eggs. Zona‐free mouse eggs prepared by the method of Boldt and Wolf (Gamete Res 13:213–222, 1986) were labeled with 125I‐concanavalin A (ConA) prior to sonication and fractionation on iso‐osmotic self‐generated Percoll density gradients. Experiments using the ConA‐specific sugar α‐methylmannoside (αMM) indicated that 125I‐ConA bound specifically to the egg PM. Greater than 95% of 125I‐ConA binding to zona‐free eggs was blocked in the presence of 0.1 M αMM, and incubation of eggs in αMM after 125I‐ConA labeling caused release of 85–90% of bound label. Fractionation of 125I‐ConA‐labeled eggs by Percoll density gradient centrifugation yielded a single radioactive peak at density = 1.025, corresponding to egg PM material. Prolonged incubation of 125I‐ConA‐labeled eggs or egg sonicates prior to fractionation did not alter the location of the radioactive peak, indicating that 125I‐ConA did not label other organelles. As a control, human erythrocytes were labeled with 125I‐ConA and fractionated under identical experimental conditions and yielded a single radioactive peak at density (1.020) comparable to that observed for 125I‐ConA‐labeled eggs. These results indicate that 125I‐ConA can be used as a specific marker to support PM isolation from small numbers of zona‐free mouse eggs.