摘要:

AbstractCross‐fertilization between sea urchin eggs (Strongylocentrotus nudus) and starfish sperm (Asterina pectinifera) was induced by treatment with polyethylene glycol (PEG). Without treatment with PEG, the denuded egg surface (jelly coat‐ and vitelline coat‐free) engulfed the head of acrosome‐reacted sperm; however, sperm penetration did not occur [Kyozuka and Osanai, 1988]. When these eggs were exposed briefly to PEG (molecular weight 3,000) in seawater, the sperm entered the egg by membrane fusion. Cortical granules were discharged, and embryogenesis began following sperm penetration. PEG did not induce parthenogenesis inStrongylocentrotuseggs. Egg activation is thus closely linked with gamete membrane

ISSN:0148-7280    

DOI:10.1002/mrd.1120220202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractFour experiments were replicated 1) to establish dose‐response relationships between lysophosphatidylcholine (LPC), sperm motility, and the acrosome reaction (AR), 2) to evaluate the influence of rabbit serum (RS) on these endpoints, 3) to compare buck differences in induction of the AR, and 4) to examine fertilizing ability in vitro of sperm tested under the first three objectives. Semen was collected from Dutch‐belted rabbits, washed once by centrifugation, resuspended, and preincubated for 2 or 4 hr in a chemically defined medium (DM), DM plus 20% RS, or BSA‐free DM plus 20% RS at 37°C. At the end of preincubation LPC was added to the preincubated sperm at concentrations of from 0 to 100 μg/ml. Sperm were examined .5–4 hr later for AR and sperm motility. For in vitro fertilization, sperm and ova were coincubated in DM up to 24 hr after insemination and in a more complex medium for another 24 hr. Addition of LPC to 4‐hr‐preincubated sperm was more effective for inducing the AR than addition to 2‐hr‐preincubated sperm. A significant increase (P<.05) in the AR occurred in 15 and 30 min following exposure to 100 and 80 μg of LPC per ml, respectively, but the higher concentration of LPC decreased sperm motility. Addition of 20% RS to DM with or without BSA surprisingly inhibited the AR but maintained sperm motility, as expected. Bucks differed (P<.05) in the initial percentage and the induced percentage of AR sperm. For the AR the optimal concentration of LPC per ml was 80 μg, but for in vitro fertilization 60 μg t

ISSN:0148-7280    

DOI:10.1002/mrd.1120220203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractIntercellular communication within the ovarian follicle has been implicated in the control of meiotic arrest and maturation in the mammalian oocyte. We have shown that a rapid down‐regulation of cumulus cell gap junctions is correlated temporally with meiotic resumption in the intact rat follicle [Larsen et al., Dev Biol, 113:517–521]. Here this relationship has been analyzed further by incubating isolated rat cumulus‐oocyte complexes (COCs) with agents known to influence germinal vesicle breakdown (GVBD) or that have been shown to modulate gap junction turnoverin vitro. Quantitative freeze‐fracture analysis revealed that cumulus cell gap junction membrane decreased significantly prior to the initiation of GVBD in COCs incubated in medium lacking serum or other additives. The addition of serum and follicle‐stimulating hormone, an experimental condition that delayed GVBD, accelerated and augmented gap junction loss at both the cumulus cell and oocyte surface. The continuous elevation of cyclic adenosine monophosphate levels, which stimulates gap junction formation in other systems, maintained meiotic arrest but did not interfere with gap junction loss. Conversely, the complete inhibition of junctional loss by a microfilament destabilizing agent, dihydrocytochalasin B, did not alter the course of GVBD normally seen in its absence. Subsequent freeze‐fracture analysis and dye coupling experiments confirmed that cumulus and oocyte gap junctions in these preparations were intact and functional during the period of meiotic resumption. These findings suggest that factors other than cumulus and oocyte gap junction turnover are required for the control of meiotic arrest and maturation in the isolated COC. However, these results do support our earlier suggestion that gap junction loss within the cumulus oophorus is instrumental in isolating the oocyte from the regulatory influence of its underlying membrana granulosa cells during meiotic maturation in the intact preovulatory follicle [Larsen et al., Dev Biol,

ISSN:0148-7280    

DOI:10.1002/mrd.1120220204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractCapacitation of hamster caudal spermatozoa at a density of 1 × 106/ml is associated with a progressive rise in cAMP levels that precedes the onset of hyperactivated motility. This increase is not expressed by caput spermatozoa incubated under identical conditions. Both the incidence of hyperactivation and the rise in cAMP levels are severely attenuated in the absence of exogenous calcium. Neither factor is restored to control levels by the addition of the phosphodiesterase inhibitor IBMX, although in the presence of exogenous calcium, this reagent increased cAMP levels, stimulated percentage motility and advanced the appearance of hyperactivation.Treatment of spermatozoa at a density of 1 × 106/ml with the calmodulin antagonist, calmidazolium (CZ), caused severe disruption of sperm motility and abolished hyperactivation, while causing only a slight reduction in cAMP content. Addition of IBMX in the presence of CZ elevated cAMP content to levels higher than normally observed during capacitation but did not restore either coordinated or hyperactivated motility.To determine both the mechanisms responsible for this elevation of cAMP content and the changes that occur during epididymal maturation to facilitate the expression of this increase, the free cytosolic calcium concentration, ATP levels, and intracellular pH of caput and caudal cells were compared. The calcium content of caudal spermatozoa rose significantly at a time when cAMP levels were increasing, while ATP content and intracellular pH fell. However, the inability of caput spermatozoa to express a rise in cAMP content was not due to deficiencies in any of these factors.These results indicate a positive role for the cAMP rise in the expression of hyperactivated motility and that the fundamental control mechanism governing both these events may be the influx of calcium that accompanies capacitation in this specie

ISSN:0148-7280    

DOI:10.1002/mrd.1120220205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of transglutaminase (TGase) substrates putrescine, dansylcadaverine, spermine, etc., and the TGase inhibitor cystamine were tested on the motility of demembranated mammalian spermatozoa. These products blocked within a few seconds the motility of demembranated reactivated spermatozoa at concentrations ranging from 0.25 to 5 mM. These minimal inhibitory concentrations could be decreased 5–150‐fold when TGase substrates and inhibitor were incubated with demembranated spermatozoa for 15 min prior to the addition of Mg·ATP. The inhibition was reversed by higher concentrations of Mg·ATP but none of these TGase substrates or inhibitor could inhibit bull sperm dynein ATPase. TGase activities, as measured by the incorporation of3H‐putrescine into TCA‐precipitable proteins, were present in both sperm Triton‐soluble and ‐insoluble fractions. On the other hand, amine acceptor protein substrates for the TGase‐catalyzed reaction were present only in the insoluble fraction. The Triton‐soluble TGase was similar to the known “tissue” TGases; the Triton‐insoluble TGase activity was calcium independent. The same TGase substrates and inhibitor that blocked the motility of reactivated spermatozoa also blocked TGase activities. Linear relationships were observed between the concentrations of these substances required to block sperm motility and those to block TGase activities. These data suggest the involvement of a TGase act

ISSN:0148-7280    

DOI:10.1002/mrd.1120220206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractBovine spermatozoa were incubated in vitro with lysophosphatidylserine (LPS), lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), lysophosphatidylinositol (LPI), or trypsin. Capacitation of sperm was evaluated by penetration of the zonae pellucidae of dead bovine oocytes. Capacitation times could be shortened to 3 h or less by treatment of spermatozoa with each of these lysophospholipids (LPLs) (P<.05). The maximum oocyte penetration percentages for individual LPLs were 40% for 10 μM LPS, 24% for 160 μM LPC, 31% for 320 μM LPE, and 19% for 320 μM LPI. Capacitation also was facilitated (P<.01) by trypsin treatment of spermatozoa. Spermatozoa treated with 250 or 2,500 units/ml of trypsin penetrated more oocytes (17 and 18%) than spermatozoa treated with 0 or 25 units/ml of trypsin (0 and 3%).Spermatozoa treated with increasing concentrations of LPL showed a decrease in both the percentage of intact acrosomes and of progressively motile spermatozoa. Increasing levels of trypsin in the incubation medium also led to a decrease (P<.05) in the percentages of intact acrosomes and a decrease (P<.01) in the percentages of progressively motile spermatozoa.Percentages of live, ovulated oocytes fertilized by spermatozoa incubated for 1 h in LPS (86%, 6/7) were not different from those incubated for 24 h in control medium (71%, 5/7). Percentages of oocytes fertilized with both of these capacitation treatments were higher (P<.05) than for oocytes exposed or killed or uncapacitated sperm.Rapid induction of capacitation and the acrosome reaction can be accomplished by exogenous treatment of bovine sperm with lysophospholipids or tryp

ISSN:0148-7280    

DOI:10.1002/mrd.1120220207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe fibrous sheath from rat epididymal sperm was isolated by sequential extraction, first with Triton X‐100 and dithiothreitol, and then with 6 M urea and dithiothreitol. The latter extraction procedure solubilized most of the sperm components, leaving the head and the fibrous sheath as the only intact structures. This material was purified by sucrose gradient centrifugation. Electron microscopy confirmed the purity of the isolated material and revealed the characteristic structural features of the fibrous sheath.Polyacrylamide gel electrophoresis (in the presence of sodium dodecyl sulfate) of the fibrillar material, showed a complex polypeptide composition. The polypeptides with molecular weights of 80,000, 24,000, and 11,500 accounted for about 65% of the total protein of the fibrous sheath. Peptide map analyses indicated that the components of molecular weights of 80,000 and 24,000 are unrelated to the polypeptides of similar size of the outer dense fibers. On the other hand, it appears that the fibrous sheath and the outer dense fibers share the polypeptide of 11,500 daltons. The component of 80,000 daltons contains on the average about 3 mol of phosphoserine per mol of polypeptide, indicating that the most abundant polypeptide of the fibrous sheath is a phosphoprotei

ISSN:0148-7280    

DOI:10.1002/mrd.1120220208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe functional organization of the nucleus in the oocytes from human antral follicles was examined by morphological and autoradiographic analysis methods at the light and electron microscopic level. According to the position of the nucleus, the level of its transcriptional activity, and the pattern of distribution of structures in it, oocytes fall into two groups. In the first one, the oocytes with the nucleus in the central position are characterized by the distribution of numerous structures all over the nucleus or by a different extent of aggregation of chromatin around the nucleolus. The nuclei of these oocytes are characterized by [3H]uridine incorporation, the label being localized over purely fibrillar, agranular nucleoli and over dispersed fibrillar chromatin adjacent to either the regions of densely packed chromatin or fibrillar‐granular material of the nucleolus‐like bodies. The latter, the same as condensed chromatin, do not incorporate [3H]uridine. In the second group, the nuclei are displaced towards the oocyte's periphery, and chromosomes surround the nucleolus as a continuous mass closely adjacent to its surface, thus forming a karyosphere. The karyosphere formation takes place on the background of cessation of nuclear transcriptional activity. A fully formed karyosphere represents a complex of closely associated inactivated structures: Nucleolus, chromosomes, and nucleolus‐like bodies. The karyosphere nucleolus bears no granules and consists of densely packed finely fibrillar material (fibrils 3 nm thick). Two zones (central and peripheral) can be distinguished in a nucleolus. Nucleolus‐like bodies, consisting of granules 20 nm in diameter embedded in finely fibrillar material, are often associated with chromosomes.In this study, data obtained by observations on the loss of association between the oocyte (with karyosphere) and corona radiata cells are evaluated. The relation of the karyosphere formation to the atresia process and the duration of karyosphere existence in human antral follicles are also di

ISSN:0148-7280    

DOI:10.1002/mrd.1120220209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe preimplantation embryo is highly resilient to experimental manipulations. A specific manipulation that has revealed many clues to the developmental process is chimera production. Chimeras have been used to describe the importance of developmental characteristics of embryonic cells and how these characteristics are involved with developmental fate. These characteristics have been monopolized in the production of interspecific chimeras and the production of transgenic animals. This review attempts to discuss the major factors affecting preimplantation mammalian embryo chimera production.

ISSN:0148-7280    

DOI:10.1002/mrd.1120220210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0148-7280    

DOI:10.1002/mrd.1120220201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY