bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic organic pH buffers can support fertilization of guinea pig eggs, but not as efficiently as bicarbonate buffer
Authors: Bhattacharyya Amitabha , Yanagimachi R. 
Published: February 2005

AbstractBicarbonate ions (HCO3−) in the medium are not absolutely essential for the fertilization of guinea pig eggs. However, fertilization takes place most efficiently in HCO3−‐buffered medium. Capacitation, the acrosome reaction, and zona penetration by spermatozoa can occur in HCO3−‐free media with synthetic organic buffers (i.e., MOPS, TES, HEPES, Tris, and TAPSO) but not as efficiently as in the HCO3−‐buffered medium. It appears that HCO3− functions as more than just a pH‐buffering molecule.
Effects of induction current and other factors on large‐scale electrofusion for pronuclear transplantation of mouse eggs
Authors: Kono T. , Tsunoda Y. 
Published: February 2005

AbstractIn this paper, we describe the procedure of large‐scale and efficient electrofusion for pronuclear transplantation in mouse eggs and the tolerance of the eggs for electric stimulus, assessed in vitro and in vivo development. The fusion chamber was arranged in parallel by dielectrodes (30‐mm length, 1‐mm width, and 2‐mm height), and 0.3 M mannitol in distilled water was used as a fusion solution. The agglutination cleavage of enucleated eggs with karyoplast was easily orientated in parallel with electrodes by alternating current between 100 and 500 kHz at 2 and 10 V/mm. Immediately after the orientation, a direct current of 150 V/mm was given for 200 μsec twice and repeated three times to induce fusion of the enucleated eggs with karyoplast. More than five eggs, at least, can be submitted to electrofusion at the same time. The eggs that were not fused were treated again in the same manner. The proportion of eggs fused with karyoplast was increased by preincubation in M16 medium prior to submitting them to the electrofusion. When the eggs were incubated for 60 min, 80% of them were fused with karyoplast by the first electric treatment; in contrast, only 19% of the eggs were fused if they were submitted to electrofusion directly. It was found that between the CD‐1 and F1 strains there was a difference in tolerance of the eggs to electric stimulus and that this was depend on the nuclei but not on cytoplasm. The proportion of development to blastocyst in the eggs fused with the pronuclear karyoplast derived from F1 (75 and 71%) was twice that of the eggs fused with the pronuclei derived from CD‐1 strain (25 and 37%). After transfer to recipients, live young were obtained from both the eggs fused with karyoplast following one or two electrofusion exposures.
Time sequence of germinal vesicle breakdown in pig oocytes after cycloheximide and p‐aminobenzamidine block
Authors: Kubelka M. , Motlík J. , Fulka J. , Procházka R. , Rimkevičová Zora , Fulka J. 
Published: February 2005

AbstractAll porcine oocytes cultured 20 hr in medium with 10 μg/ml cycloheximide rested in the germinal vesicle (GV) stage but with the highly condensed bivalents in nucleoplasm. When these oocytes were washed and cultured in the control medium for 2, 4, and 6 hr, germinal vesicle breakdown (GVBD) was completed in 0, 86, and 100% of them, respectively. When similarly inhibited oocytes cultured successively only 2.5 hr in the control medium were given again in cycloheximide enriched medium (3.5 hr), nearly all of them reached late diakinesis stage again. It means that oocytes cultured for 20 hr and washed free of this inhibitor of protein synthesis completed GVBD rapidly (4 hr) and protein synthesis crucial for nuclear membrane disintegration occurred already during the first 2 hr after washing of inhibitor. All oocytes cultured for 20 hr in medium with 1 mM p‐aminobenzamidine rested in GV with chromatin around the compact nucleolus. The successive culture in cycloheximide (20 hr) and p‐aminobenzamidine (10 hr) prevented GVBD in all oocytes, too. In contrast, when the oocytes washed after cycloheximide block (20 hr) were cultured in p‐aminobenzamidine enriched medium 2 and 3 hr and again for 6 hr in cycloheximide medium, the nuclear membrane dissolved in 62 and 68% of oocytes, respectively. These data suggest that inhibition of protein synthesis in pig oocytes does not prevent the high condensation of bivalents in GV. However, nuclear membrane breakdown requires the successive protein synthesis and proteolysis.
Partial characterization of a fraction from human follicular fluid that initiates the human sperm acrosome reaction in vitro
Authors: Siiteri Jon E. , Gottlieb Wayne , Meizel Stanley 
Published: February 2005

AbstractA human follicular fluid (HFF) fraction prepared by Sephadex G‐75 column chromatography has been previously shown by this laboratory to initiate the human sperm acrosome reaction (AR) in vitro. In the present report, the apparent molecular weight (MW) of this AR activity determined by a longer G‐75 column than was used in the previous work was 50,000 ± 5,106. The G‐75 Sephadex void volume fractions of some but not all HFF samples were also found to contain some AR‐initiating activity. The occasional void volume activity was less potent than that of the 50,000 MW fraction and was not studied further. Further characterization of the 50,000 MW fraction was carried out. A time‐course study demonstrated that maximum AR were obtained within 5 min following the addition of the 50,000 MW fraction. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) followed by silver staining revealed that the 50,000 MW fraction was still a relatively crude preparation. Treatment of the 50,000 MW fraction with chloroform:methanol did not extract the AR‐initiating activity into the lipid phase. The AR‐initiating activity of the untreated 50,000 MW fraction was precipitated when it was boiled, but the activity was partially resistant to boiling after overnight incubation. Treatment of the 50,000 MW fraction with pronase E or with several glycosaminoglycan hydrolases did not destroy the activity. Pronase treatment resulted in a higher amount of boiling‐resistant AR‐initiating activity. The AR‐initiating activity of the untreated 50,000 MW fraction was partially dialyzable, but the activity of an undialyzed fraction did not pass through an ultrafiltration membrane with a 10,000 MW cut‐off. However, treatment of the 50,000 MW fraction with protease, peptide:N‐glycosidase F, and to a lesser extent chondroitinase ABC yielded an active lower MW activity which could pass through such an ultrafiltration membrane. The lower MW activity released by peptide:N‐glycosidase F eluted in the included volume (5,000–1,000) of a Sephadex G‐25 column. Neutral hexose but not protein or peptide was detected in the G‐25 peak of AR‐initiating activity. These results suggest that the AR‐initiating activity present in the 50,000 MW fraction of HFF: (1) is present either as two different AR factors (a high‐MW factor and a low‐MW, noncovalently bound factor) or as a single factor responsible for both the nondialyzable and dialyzable AR‐initiating activities (the latter being enzymatically released from the former), and (2) may be at least partially associated with N‐linked oligosaccharides of a glycoprotein or proteoglycan.
Intracellular pH change does not appear as a prerequisite for triggering activation of Barnea candida (Mollusca, Pelecypoda) oocytes
Authors: Brassard M. , Duclohier H. , Moreau M. , Guerrier P. 
Published: February 2005

AbstractBarnea Candida oocytes, exposed to excess KCl, ammonia, or digitonin, exhibit germinal vesicle breakdown (GVBD) and reinitiate meiosis, at least up to first polar body extrusion. While we confirm that KCl—but not ammonia‐induced activation requires external calcium, our findings that digitonin is effective at any pH from 6 to 8, in the presence of calcium, while the phorbol ester TPA and diacylglycerol fail to reinitiate meiosis, strongly suggests calcium as the main trigger for this process. Preliminary experiments using the fluorescent probes fluorescein diacetate and Quin 2/AM show, moreover, that KCl and ammonia produce both an intracellular calcium surge (30 nM) and a slight alkalinization of the intracellular cytoplasm from 7.84 to 8.05.
Effect of in vitro storage of bovine spermatozoa on acrosomal integrity, proteolytic activity, binding, and initiation of penetration of oocytes
Authors: Miller B. J. , Graves C. N. , Lodge J. R. 
Published: February 2005

AbstractDuring a 10‐day 5°C storage and subsequent 4–6‐hr 37°C incubation, both percent live spermatozoa and percent spermatozoa with an intact acrosome decreased, and percent spermatozoa with a late‐reacted or without an acrosome increased. When stored spermatozoa were mixed with oocytes, no decrease in percent of oocytes with spermatozoa bound or percent of oocytes with spermatozoa starting to penetrate occurred as storage time increased. A 58% decrease in acrosin gelatinolytic activity and a 56% decrease in acrosin esterolytic activity but no decrease in nonacrosin proteolytic activity were evident over the 10‐day storage. These studies show that a change in acrosomal morphology as well as a loss of acrosin may be responsible for the decreased fertility following extended in vitro storage of mammalian spermatozoa.
Sperm tail differentiation in the nudibranch mollusc Hypselodoris tricolor (gastropoda, opisthobranchia)
Authors: Medina A. , Moreno F. J. , García‐Herdugo G. 
Published: February 2005

AbstractThe sperm axoneme of Hypselodoris tricolor forms from a single centriole that is located initially beneath the plasma membrane and then migrates to the nuclear surface. A conspicuous centriolar adjunct‐like formation is present in the neck of midspermatids, but it becomes very reduced at the end of spermiogenesis. In spermatocyte and spermatid mitochondria, intracristal bodies originate from the accumulation of a dense material in some cristae. From our observations and foregoing reports, it may be concluded that the process of sperm tail differentiation in opisthobranchs resembles that in pulmonates, whereas it differs in many respects from that occurring in prosobranchs. The appearance of intracristal bodies in modified mitochondria seems to be a special feature of spermatogenesis in the opisthobranchs that does not occur in the two other groups of gastropod molluscs.
Binding of chemotactic peptide to the outer surface and to whole human spermatozoa with different affinity states
Authors: Ballesteros Luz Ma. , Delgado Nestor M. , Rosado Adolfo , Correa Carlos , Hernandez‐Perez Omar 
Published: February 2005

AbstractBinding of N‐formyl‐methionyl‐L‐leucyl‐[3H]phenylalanine (fML[3H]Ph) to human ejaculated spermatozoa and to its isolated plasma membrane was studied. Our data confirm the presence of specific receptors for f‐MLPh in the human spermatozoa and suggest that whole spermatozoa receptors exist in two affinity states, one high‐affinity, low‐capacity specific receptor (Kd = 12.3 ± 0.5 nM, n = 22,285 ± 65,008 binding sites per sperm cell) and a second one (Kd = 700 ± 47 nM) that is not saturable, indicating a low‐affinity, high‐capacity nonspecific site. In contrast, sperm membrane showed only one class of binding site (Kd = 6.4 ± 0.12 nM), which was statistically different from that of the high‐affinity binding site of intact spermatozoa. To explain this difference we discuss the possibility that first, the two binding affinities represent two interconvertible states of a single receptor population, which, depending on the metabolic activity of spermatozoa, may change its physicochemical properties; or second, they reflect two different processes, binding and/or transport into the spermatozoa.
Behavior of sperm nuclei in intact and bisected metaphase II mouse oocytes fertilized in the presence of colcemid
Authors: Borsuk Ewa , Mańka Renata 
Published: February 2005

AbstractOur objective was to examine the developmental fate of sperm nuclei in oocytes fertilized under conditions of meiotic arrest. Therefore zona‐free metaphase II oocytes and oocyte fragments (nucleate and anucleate) were fertilized in the presence of colcemid. In anucleate oocyte fragments, normal male pronuclei develop. In contrast, in intact oocytes and nucleate fragments sperm nuclei after initial decondensation undergo secondary condensation. This state is maintained as long as the oocytes are treated with colcemid. When the drug is removed 3 h after insemination, the meiotic spindle(s) is reconstructed, the second polar body(ies) is extruded, and a female pronucleus (or micronuclei) forms. At the same time the sperm nucleus decondenses again and transforms into a male pronucleus. In addition oocytes fertilized in the presence of colcemid could not be refertilized. These observations suggest that oocytes and oocyte fragments fertilized in the presence of colcemid undergo activation despite the failure of pronucleus formation. The inhibitory effect of colcemid on the formation of pronuclei is expressed only in the presence of oocyte chromosomes. We suggest that colcemid stabilizes factors responsible for chromosome condensation that are associated with oocyte chromosomes but not factors (whether the same or different) present in the cytoplasm.
An influx of extracelluar calcium is required for initiation of the human sperm acrosome reaction induced by human follicular fluid
Authors: Thomas Paul , Meizel Stanley 
Published: February 2005

AbstractThe role of Ca2+ in the human sperm acrosome reaction was investigated using the fluorescent calcium indicator fura‐2. Previous experiments have shown that a Sephadex G‐75 column fraction of human follicular fluid can stimulate the human sperm acrosome reaction [Suarez SS, Wolf DP, Meizel S (1986): Gamete Res 14:107–121]. Using fura‐2, we demonstrated that this Sephadex G‐75 fraction also stimulates a rapid, transient increase in intracellular free Ca2+. This Ca2+ transient is blocked either by chelation of extracellular calcium or by addition of the Ca2+ antagonist La3+. We have also been able to stimulate the acrosome reaction in human sperm without significant loss of motility, using the divalent cation ionophore ionomycin. Acrosome reactions stimulated by whole follicular fluid, the G‐75 fraction, or ionomycin are all blocked by removal of extracellular Ca2+. These results strongly suggest that an influx of extracellular Ca2+ is responsible for intiating the acrosome reaction in human sperm treated with human follicular fluid. This is the first demonstration in mammalian sperm that a potentially physiological stimulus can cause an increase in intracellular Ca2+ concomitant with the acrosome reaction.
Success of fertilization in golden hamsters is a function of the relative gamete ratio
Authors: Stewart‐Savage J. , Bavister Barry D. 
Published: February 2005

AbstractGamete concentrations can be expressed as either absolute gamete ratios (sperm/egg), the concentration of the motile sperm (sperm/ml), or as a relative gamete ratio (sperm/egg × ml). We demonstrate that the success of hamster fertilization in vitro is a function of the relative gamete ratio and that any effect of the insemination medium geometry is minimal. Consistent fertilization occurs when the relative gamete ratio is above 103.5 sperm/egg × ml, but becomes variable above 105.0 sperm/egg × ml. At suboptimal relative gamete ratios, there is a strong sperm concentration effect on both the consistency and level of fertilization, whereas the absolute gamete ratio only affects the overall level of fertilization. These effects are seen when the sperm concentration is below 103.5 sperm/ml and when the absolute gamete ratio is below 102.3 sperm/egg. These influences are probably due to reduced sperm survival at low sperm concentrations and due to a sampling error that occurs when small numbers of sperm are transferred. When the absolute gamete ratios found in vivo in the hamster [Cummins and Yanagimachi, 1982, Gamete Res 5, 239–256] are converted to relative gamete ratios, they are similar to our in vitro results. Thus relative gamete ratios allow, for the first time, comparison between in vitro and in vivo data in the hamster, and between other rodents.
Analysis of calmodulin acceptor proteins and the influence of calmodulin antagonists on human spermatozoa
Authors: Aitken R. J. , Clarkson J. S. , Hulme M. J. , Henderson C. J. 
Published: February 2005

AbstractThe possible role of calmodulin in regulating a number of calcium‐dependent functions exhibited by human spermatozoa was investigated by using the antagonists trifluoperazine and calmidazolium. At high doses both antagonists inhibited the motility of human spermatozoa and induced a concomitant rise in [Ca2+]i and a decline in cAMP. Lower doses of these antagonists, particularly calmidazolium, suppressed the ability of human spermatozoa to generate reactive oxygen species and exhibit sperm‐oocyte fusion, without influencing [Ca2+]i, cAMP, or motility. This inhibition of sperm‐oocyte fusion was effective even if the spermatozoa were subsequently exposed to A23187, suggesting that calmodulin may regulate this aspect of human sperm function at a point downstream from calcium influx.Both radiolabelling and affinity chromatography techniques were used to detect a number of calcium‐dependent and calcium‐independent calmodulin acceptor proteins in the human spermatozoon. The major calcium‐dependent acceptor proteins exhibited Mr values of 32,000 and 22,000–27,000, respectively, and did not appear to be associated with the sperm plasma membrane.
Development of enucleated parthenogenones that received pronuclei or nuclei from fertilized mouse eggs
Authors: Tsunoda Y. , Shioda Y. 
Published: February 2005

AbstractThis study compares the developmental potential of enucleated mouse parthenogenones that received pronuclei from fertilized eggs with those that received nuclei from late two‐cell embryos. The proportion of reconstituted parthenogenones, which received pronuclei at the one‐cell stage, that developed to blastocysts in vitro and to live fetuses after transfer to recipients was significantly lower than that of reconstituted control eggs. However, the in vitro and in vivo developmental potential of reconstituted parthenogenones that received nuclei at the two‐cell stage from fertilized late two‐cell embryos was not different from that of reconstituted control eggs.These results were contrary to those reported previously by Mann and Lovell‐Badge (1984), who showed that parthenogenetic eggs receiving pronuclei from fertilized eggs developed well both in vitro and in vivo.
A gonadotropin‐releasing hormone agonist and an activator of protein kinase C improve in vitro oocyte maturation in Macaca fascicularis
Authors: Lefèvre B. , Gougeon A. , Peronny H. , Testart J. 
Published: February 2005

AbstractCynomolgus monkey oocytes were recovered from follicles > 1,000 μm in diameter at day 8 in gonadotropin‐stimulated cycles and cultured in vitro for 2 days. Germinal vesicle breakdown (GVBD) occurred in 30.3% of control oocytes (n = 76) compared with 54.0% and 55.0% of oocytes cultured in presence of a gonadotropin‐releasing hormone agonist (GnRHa), Buserelin (n = 50), or a protein kinase C activator, 1‐oleoyl‐2‐acetyl‐rac‐glycerol (OAG, n = 40), respective (P < .01). As similar results were obtained using OAG or Buserelin, we hypothesize that the action of Buserelin upon the primate oocyte is protein‐kinase‐C dependent. The possible effects of Buserelin on in vivo oocyte maturation have to be detemined.
Capacitation potential of the fallopian tube: A study involving surgical insemination and the subsequent incidence of polyspermy
Authors: Hunter R. H. F. , Nichol R. 
Published: February 2005

AbstractIn an attempt to demonstrate limitations in the capacitating potential of the Fallopian tube, ejaculated boar spermatozoa were introduced directly into the isthmus at varying intervals before ovulation. The incidence and degree of polyspermy subsequently observed were taken as indicators of the population of capacitated spermatozoa confronting the newly ovulated eggs: the more extensive the condition of polyspermy, the greater the number of capacitated spermatozoa presumed to have been available at the site of fertilization. Results are based on 673 eggs from 53 animals.When suspensions containing 2.21–3.87 × 108 sperm per ml were introduced 36–40 hours and 26–30 hours before ovulation, 85% and 61% respectively of the eggs were polyspermic, such eggs exhibiting mainly dispermy and trispermy. By contrast, when comparable sperm suspensions from the same boar were instilled 17–18 hours before ovulation, 70% of the eggs were polyspermic but the degree of polyspermy had increased dramatically: most eggs contained 40 or more sperm heads in the vitellus, invariably forming swollen chromatin aggregates rather than male pronuclei. Surgical insemination at times closer to ovulation significantly reduced the incidence and degree of polyspermy, reaching a low of 2% with insemination 1–2 hours before ovulation. These results therefore support the concept of a limited capacitation potential of the Fallopian tube.In a separate series of observations, mating animals shortly before surgical insemination with sperm suspensions from the same boar markedly reduced the incidence of polyspermy. This latter observation may be of clinical significance in procedures of laparoscopic or transcervical insemination into the tubes to alleviate human infertility. The manner whereby myosalpingeal physiology could be modified in response to coital stimulation is discussed.
Inhibition of adenosine‐metabolizing enzymes modulates mouse sperm fertilizing ability: A changing role for endogenously generated adenosine during capacitation
Authors: Monks Nicola J. , Fraser Lynn R. 
Published: February 2005

AbstractThe effect of inhibiting adenosine‐metabolizing enzymes on sperm fertilizing ability was studied to investigate a possible role for endogenously generated adenosine in the regulation of capacitation. The compounds used have been shown to be effective inhibitors of the relevant enzymes in similarly incubated mouse sperm suspensions. Inhibition of 5′‐nucleotidase activity with α,β‐methylene adenosine 5′‐diphosphate (AMPCP), to reduce available endogenous adenosine, caused a dose‐dependent inhibition of the fertilizing ability of partially capacitated spermatozoa, which was significant with 100 and 250 μM AMPCP. Conversely, inhibition of adenosine deaminase with 100 nM coformycin, to increase available endogenous adenosine, promoted the fertilizing ability of partially capacitated spermatozoa when the fertilization rate of control suspensions was low. However, coformycin had no effect on sperm suspensions with moderate fertilizing ability, and it inhibited fertilizing ability when added to capacitated spermatozoa. These data are consistent with a promotion of the early stages of capacitation by endogenously generated adenosine and suggest that sensitivity to adenosine changes as capacitation proceeds. Because the majority of adenosine‐metabolizing enzyme activity resides in or is directed toward the extracellular compartment in such suspensions, these effects of adenosine may be mediated at the outer surface of the cell. By interacting with receptors on adenylate cyclase, externally produced adenosine could modulate intracellular levels of cyclic adenosine monophosphate (cAMP), thereby influencing fertilizing ability.