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  • Life and Medical Sciences  (6,945)
  • 1985-1989  (6,292)
  • 1950-1954  (653)
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  • 201
    Electronic Resource
    Electronic Resource
    Immunogold distribution of actin during sperimiogenesis in the normal rabbit and after experimental cryptorchidism (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 281-290 
    Details
    ISSN: 0148-7280
    Keywords: immunocytochemistry ; perinuclear substance ; F-actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Immunogold procedures for actin detection were used in combination with experimental cryptorchidism in the rabbit as a modei to shed more light on the function of subacrosomal actin during spermiogenesis. In the normal testis, actin was localized in the perinuclcar substance (PNS) from round spermatid onward but it was not detected in late spermatids. Actin labeling in each type of spermatid was essentially unmodified after 24 hr of cryptorchidism. However, among relevant immediate and delayed effects, discontinuous acrosomes overlying a continuous PNS with normal actin labeling were noted. Nuclear invaginations were seen in combination with subacrosomal dilatations: at this site actin labeling was found only in the PNS closely apposed to the nuclear envelope. In subacrosomal areas lacking PNS, actin labeling also was lacking. These results suggest that the subacrosomal actin (F-actin) is a component of the PNS that is tightly bound to the nuclear envelope rather than the overlying inner acrosomal membrane. Therefore, a function for the subacrosomal actin either in anchoring the acrosome to the nucleus or in capping the inner acrosomal membrane appears unlikely. The data rather suggest a capping function for the nuclear membrane during spermiogenesis.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120240305
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  • 202
    Electronic Resource
    Electronic Resource
    Ultrasound-guided transfundal uterine sperm recovery from Macaca fascicularis (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 327-331 
    Details
    ISSN: 0148-7280
    Keywords: uterine fluid ; sperm transport ; macaques ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previous studies from this center have indicated that the cynomolgus macaque (Macaca fascicularis) may serve as a model for human sperm interaction with the cervix and uterus. In some macaque species, transcervical aspiration of the uterine contents carries a significant risk of disturbing the cervical milieu due to the serpentine nature of the cervix. The only alternatives have been surgical procedures such as laparotomy or laparoscopy. In this paper, we report our experience with a new technique for ultrasound-guided sampling of spermatozoa in the macaque uterus. Twenty adult female cynomolgus macaques were monitored for menses (first day of menses = day l), and one mating per cycle was allowed on day 10, 11, or 12. In one group of ten animals, cervical mucus was sampled at 3 or 18 hr postcoitus (pc) and ultrasound-guided uterine aspiration was performed at 24 hours pc. In a second group of ten monkeys, uterine aspiration was at six hr pc and sperm numbers and motility were counted in the uterine fluid. Uterine fluid was obtained from fourteen of twenty monkeys. Pregnancy occurred in ten of the twenty experimental cycles. Ultrasound-guided uterine aspiration appears to be a reliable method for the evaluation of sperm transport in female macaques. The correlations between uterine sperm recovery and cervical mucus sperm populations arc discussed. The high conception rate in treatment cycles indicates that this procedure can be performed without apparent risk to pregnancy.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120240308
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  • 203
    Electronic Resource
    Electronic Resource
    Endpoint of first stage of zona pellucida-induced acrosome reaction in mouse spermatozoa characterized by acrosomal H+ and Ca2+ permeability: Population and single cell kinetics (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 303-326 
    Details
    ISSN: 0148-7280
    Keywords: 9-amino acridine pH probe ; fura-detected Ca2+ influx into acrosomal compartment ; cell population kinetics ; flagellar motion amplitude ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The acrosome reaction induced by the mouse egg's zona pcllucida in mouse sperm has been shown to proceed in two stages as characterized empirically by sequential changes in patterns of chlorletracycline fluorescence on the sperm plasma membrane surfaces. The chlortctracy-cline fluorescence pattern characteristic of fully intact sperm is designated B:in sperm bound to structurally intact zonae that induce the acrosome reaction, the B pattern changes first to an intermediate pattern S and then to a terminal pattern AR characteristic of the completed acrosome reaction. In the same study, it was shown, using a 9-amino acridine fluorescent pH probe, that completion of the first stage was characterized by increase in H+ permeability such that the H+ gradient between sperm head and medium was dissipated. In this study, we show that the fluorescent pH probe 9-N-dodecylamino acridine and the intracellular Ca2+ fluores cent probe fura-2 are both localized to the anterior part of the sperm head encompassing the acrosomal compartment in intact sperm, and the fluorescence associated with each probe is lost as the first stage of the acrosome reaction is completed. Loss of the pH probe fluorescence, pattern N, corresponds to onset of H+ permeability, and loss of fura-2 fluorescence, pattern F, corresponds to onset of Ca2+ permeability. Localization of intracellular fura-2 fluorescence to the acrosomal compartment required extracellular Mn2+ to quench surface-bound fura-2 AM, the tetra-acetoxymethyl ester of fura-2 used to load the cells. Loss of acrosomal fura-2 fluorescence is due to quenching by tracer Mn2+ accompanying Ca2+. Onset of membrane permeability to both H+ and Ca2+, asseenby loss of patterns N and F, occurred in synchrony in populations of sperm bound to isolated, structurally intact zonae, with an overall time coursfe of 210 min postbinding. The loss of pattern N in individual sperm cells bound to zonae was rapid, with a half time of 2.1 min. Concomitant with this rapid loss of pattern N was a shift in the amplitude of flagellar motion from large to small. The lag times to pattern N loss in 50 individual cells ranged from 30 to 140 min. The variable lag times determine the population kinetics; the rate of the endpoinl reaction seen in the individual cells is rapid and constant.Dissipation of the H+ gradient with immediate loss of pattern N was readily achieved by addition of nigericin with no change in the time course of the onset of Ca2+ permeability of the membranes enclcsing the acrasome. Onset of Ca2+ permeability was always accompanied by onset of H+ permeability, but the alkalinization caused by H+ permeability induced by nigericin had no effect on Ca2+ permeability in intact sperm. This indicates that the permeabilization of the membranes marking the endpoint reaction of the B-to-S transition is most likely due to pore formation induced by punctate fusion of the plasma and outer acrasomal membranes, as would be expected for an exocytotic reaction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120240307
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  • 204
    Electronic Resource
    Electronic Resource
    In Vitro maturation and fertilization of domestic cat follicular oocytes (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 343-356 
    Details
    ISSN: 0148-7280
    Keywords: maturation of oocytes ; chromosomes ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The time course and conditions necessary for oocyte maturation and subsequent fertilization in vitro were studied in the domestic cat. Darkly pigmented oocytes surrounded by cumulus cells and a tight corona radiata were collected from ovaries removed at ovariohysterectomy. After culture in Eagle's minimum essential medium, oocytes were evaluated for nuclear maturation by analyzing chromosomal spreads. Oocytes achieved metaphase II after intervals of 40-48 hr of in vitro incubation. The incidence of maturation was enhanced (P〈0.05) when oocytes were recovered from inactive (54%) or follicular (56%) stage donors compared to those recovered from luteal phase (29%) or pregnant (35%) cats. The proportion of oocytes successfully maturing in vitro in medium containing no hormone supplementation (37%) was less (P〈0.01) than counterparts cultured in follicle-stimulating hormone (FSH) only (48%) or FSH and luteinizing hormone (LH) (54%). The efficiency of maturation was not influenced (P 〉0.05) by either maintenance/transport temperature (4°C vs. 22°C) or delaying recovery of oocytes from antral follicles (2-8 hr vs. 24-32 hr). Approximately 36% of the in vitro matured oocytes cocultured with spermatozoa demonstrated evidence of fertilization; however, there appeared to be a critical development period for maximizing the incidence of fertilization. These results demonstrate that domestic cat antral oocytes are capable of maturing in vitro, and maturation is influenced by the reproductive status of the donor and the presence of gonadotropins in the culture medium. These oocytes are capable of forming embryos and developing to at least the 16-cell stage in vitro.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120240310
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  • 205
    Electronic Resource
    Electronic Resource
    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220101
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  • 206
    Electronic Resource
    Electronic Resource
    Status of the rat acrosome during sperm-zona pellucida interactions (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 1-13 
    Details
    ISSN: 0148-7280
    Keywords: fertilization ; spermatozoa ; acrosome ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Over the past 40 years evidence from many sources has indicated that the mammalian acrosome reaction occurs within or near the cumulus oophorus. Recently, however, workers investigating in vitro fertilization in the mouse have concluded that in this system the acrosome reaction takes place on the surface of the zona pellucida. We have investigated the interaction of rat spermatozoa and the zona pellucida by using the scanning electron microscope (SEM) and two monoclonal antibodies which are directed to antigens of the rat sperm acrosome.When in vitro inseminated eggs from which the cumulus has been removed are viewed with the SEM some sperm heads on the surface of the zona pellucida appear unaltered whereas others appear to be undergoing changes. In vivo, all displayed altered head morphology. Using immunogold labeling we found that the two antibodies employed, 2C4 and 5B1, were directed to acrosomal content and vesiculating acrosomal membranes. Immunofluoresence staining of zonae pellucidae in in vitro fertilization studies revealed numerous small positive regions. These were presumably acrosomal content and membranes which had been left on the zona surface by spermatozoa which had been associated with the zona surface. Our results suggest that the rat acrosome interacts with the zona pellucida. During this interaction some acrosomal content and membranes detach from the spermatozoon and remain on the surface of the zona pellucida.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220102
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  • 207
    Electronic Resource
    Electronic Resource
    Hemizona assay using salt-stored human oocytes: Evaluation of zona pellucida capacity for binding human spermatozoa (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 15-26 
    Details
    ISSN: 0148-7280
    Keywords: fertility ; sperm binding ; zona pellucida ; in vitro fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Human oocytes were stored (25°C) in 1.5 M MgCl2 for 6-30 days, then utilized in the new hemizona assay (HZA) for tight binding of human spermatozoa [Burkman et al.: Fertil Steril 49:688-697, 1988]. We have compared 1) the ability of matching salt-treated hemizonae or dimethylsulfoxide (DMSO)-treated hemizonae to distinguish between sperm from semen having normal versus subnormal characteristics and, 2) the kinetics of fertile sperm binding to salt-treated or DMSO-treated hemizonae. After sperm preparation, one salt-treated hemizona was incubated with normal spermatozoa and the matching hemizona was placed with sperm from the subnormal group. As a control, DMSO-treated hemizonae were incubated in additional sperm droplets. After 4 hours, the number of sperm tightly bound to each hemizona was counted. Within the normal semen group, there was equivalent binding to salt- or DMSO-treated hemizonae (54.0 ± 12 and 49 ± 14, respectively, mean ± SEM). Similarly, tight binding of sperm from the subnormal group was not affected by the zona storage method (21 ± 8 and 17 ± 5, respectively). For either storage approach, binding of subnormal sperm was significantly less (P 〈 0.01) compared with the number of normal sperm attached to the matching hemizona. For the kinetics study, the hemizona binding of proven fertile spermatozoa was followed throughout 8.5 hours. The shape of the binding curve was the same for zonae stored by either method and was consistent with our published kinetics data. Salt storage offers a simple and inexpensive means for accumulating and transporting human zonae pellucida; the resulting hemizonae function effectively in the HZA for estimating sperm binding potential.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220103
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  • 208
    Electronic Resource
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    Analysis of the chromosome complement in outbred mouse sperm fertilizing in vitro (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 71-81 
    Details
    ISSN: 0148-7280
    Keywords: structural chromosome abnormalities ; first-cleavage metaphase ; sperm aging ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The chromosome complements in a population of mouse sperm from random-bred ICR donors were analyzed at first-cleavage metaphase after in vitro fertilization (IVF) of oocytes from females of the same strain. The sperm were aged as donations occurred within an average of 31 days, either since last mating or at arrival at the animal facility in the case of virgin males. Of a total of 598 sperm complements studied from 22 sexually mature males aged 10-26 weeks old, there was one diploid complement (0.17%). The frequencies of hyperhaploidy and structural aberrations that were studied in 338 complements were 4.4% and 3.6%, respectively, giving an overall frequency of 8.0%. The hyperhaploid complements consisted of n + 1, n + 2, n + 3, and n + 7 counts, while the structural abnormalities were of the chromosome type and included large and small fragments and a possible translocation. This is the highest frequency of sperm chromosome abnormalities reported for mouse sperm obtained from males under physiological conditions and fertilized in vitro or in vivo. Sperm aging, strain, and/or technique differences are among the factors that may be responsible for this high frequency. Since the 8.0% frequency of hyperhaploidy and structural abnormalities is similar to the frequency reported for human sperm after IVF, the outbred murine in vitro fertilization system may be a useful model to study the origin of human sperm chromosome abnormalities.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220108
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  • 209
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    Incidence of chromosomal anomalies in early bovine embryos derived from in vitro fertilization (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 83-91 
    Details
    ISSN: 0148-7280
    Keywords: chromosome anomalies ; bovine embryo ; in vitro fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The incidence of chromosomal anomalies in early bovine embryos derived from follicular oocytes fertilized in vitro using sperm separated by Percoll density gradient centrifugation was investigated. Overall, chromosomal anomalies were observed in 13.7% (138/1005) of embryos. There were 14 haploids (1.4%), 2 hypodiploids (0.2%), 6 hyperdiploids (0.6%), 101 triploids (10.0%), 12 tetraploids (1.2%), 2 diploid/triploid mosaics (0.2%), and 1 diploid/tetraploid mosaic (0.1%). The frequency of triploidy was caused mainly by polyspermy. There was a significant difference in the frequency of embryos with abnormal chromosomes between the two bulls used (P 〈 0.005), but Percoll centrifugation did not affect the observed incidence of anomalies. The frequency of chromosomal anomalies in embryos at each stage increased with delay or arrest of development. These results suggest that the incidence of chromosomal anomalies depended on the conditions of in vitro fertilization and the arrest of development.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220109
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  • 210
    Electronic Resource
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    Induction of cross-fertilization between sea urchin eggs and starfish sperm by polyethylene glycol treatment (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 123-129 
    Details
    ISSN: 0148-7280
    Keywords: acrosome reaction ; sperm engulfment ; gamete membrane fusion ; interclass crossing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cross-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 in Strongylocentrotus eggs. Egg activation is thus closely linked with gamete membrane fusion.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220202
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  • 211
    Electronic Resource
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    Relationship between calcium, cyclic AMP, ATP, and intracellular pH and the capacity of hamster spermatozoa to express hyperactivated motility (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 163-177 
    Details
    ISSN: 0148-7280
    Keywords: epididymal maturation ; capacitation IBMX ; calmidazolium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Capacitation 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 species.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220205
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  • 212
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    Expression and topographical localization of cell surface fucosyltransferase activity during epididymal sperm maturation in the mouse (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 321-332 
    Details
    ISSN: 0148-7280
    Keywords: glycotransferase ; plasma membrane ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have demonstrated previously that spermatogenic cells in the mouse testis have high levels of fucosyltransferase activity. Furthermore, a significant portion of this activity has been localized to the cell surface (Millette et al.: Cell Biology of the Testis and Epididymis, 1987). Differential expression of fucosyltransferases and their function as ecto-enzymes may be important in the processes of sperm maturation and fertilization in mammals. Accordingly, here we report the activity levels of fucosyltransferase (FT) in spermatozoa isolated from the mouse caput and cauda epididymides. Calculated on a per cell basis, spermatozoa from the caput epididymis have significantly more FT activity than do spermatozoa from the cauda epididymis (18.07 ± 2.2 pmol/million cells compared with 2.8 ± 0.09 pmol/million cells). Furthermore, caput sperm exhibit a more significant increase in FT activity when assayed in the presence of Nonidet P-40. Calculated on the basis of cell surface area, however, FT activity remains constant on the head portion of spermatozoa isolated from all portions of the male reproductive tract and from capacitated spermatozoa. Measurements of FT activity in extracts of isolated sperm tails from cells at different stages of maturation indicate a greatly diminished activity in tails from sperm in the cauda epididymis. The total sperm surface area is composed predominantly of the plasma membrane surrounding the flagellar apparatus. Therefore, our data demonstrate that FT activity is retained selectively on the different topological regions of sperm, with losses during sperm maturation in the epididymis being restricted to the tail segment. Maintenance of high levels of FT activity of the plasma membranes of the mouse sperm head raise the possibility that FT is indeed involved in some aspects of sperm-egg recognition.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220309
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  • 213
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    Failure of spermatozoa from T/t mice to fertilize in vitro is overcome by zona drilling (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 369-373 
    Details
    ISSN: 0148-7280
    Keywords: assisted fertilization ; t-locus mice ; in vitro fertilization ; infertility ; mouse ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Failure of epididymal spermatozoa from T/t mutant mice, but not from t/t individuals, to fertilize oocytes in vitro was partially overcome by opening a small aperture in the zona pellucida with acidified Tyrode's solution to permit direct access of the spermatozoon to the vitellus. This study provides a model system to evaluate requirements for successful zona drilling in the treatment of human infertility and further insights into the effects of the t complex on sperm fertility.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220403
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  • 214
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    Assessment of the viability and fertilizing potential of cryopreserved bovine spermatozoa using dual fluorescent staining and two-flow cytometric systems (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 355-368 
    Details
    ISSN: 0148-7280
    Keywords: bull ; semen ; fluorophore ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A dual fluorescent staining system utilizing 5 (and-6)-carboxy-4′,5′-dimethyl fluorescein diacetate (CDMFDA) and Hydroethidine (HED) was developed to provide quantifiable information reflective of spermatozoal viability and fertilizing potential. Cryopreserved spermatozoa from ten bulls on which there was fertilizing capacity information were incubated for 1.5, and 3 hr at 39°C prior to fluorogenic staining. Spermatozoa were analyzed using both a FACS Analyzer and an EPICS V flow cytometer to determine if a particular fluorescence pattern was due to an instrumental artifact or cellular processes. Five fluorescent cellular populations were identified by the FACS Analyzer and three populations by the EPICS V. Spermatozoa were quantified after each incubation time for red (HED) and green (CDMFDA) fluorescence. Viable spermatozoa retained the greatest amount of both green and red fluorescence. Dead or moribund spermatozoa had a decrease in over-all fluorescence. The number of viable cells at 0 hr plus the number of dead or morbid cells at any time period were identified by the FACS Analyzer as important in estimating the potential fertility of a bull. The EPICS V identified the number of dead or moribund cells as being related to nonreturn rates. Incubation of samples decreased cellular viability, which resulted in reduced levels of both green and red fluorescence. Similarities between data obtained with both flow cytometers illustrated that cellular processes, not instrumental artifacts, were responsible for the decrease in over-all fluorescence when viability declined, the relationship between the number of cells with specific fluorescence levels and nonreturn rates, and the incubative-induced changes in fluorescence patterns.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220402
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  • 215
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    Modification of the zona-free hamster ova bioassay of boar sperm fertility and correlation with in vivo fertility (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 385-397 
    Details
    ISSN: 0148-7280
    Keywords: male fertility ; pig ; acrosome ; heterospermic insemination ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: These studies were designed to evaluate the ability of the zona-free hamster ova bioassay to detect differences in fertility of boar sperm. In the first study, sperm from two previously infertile boars were compared to sperm from seven previously fertile boars. The percentage of zona-free hamster ova penetrated by sperm from the previously infertile boars was significantly lower than the percentage of ova penetrated by sperm from previously fertile boars (18% of ova penetrated vs. 83%, P 〈 .001). In the 14 ejaculates from the previously infertile boars that had ejaculate motilities of 50% or greater, the percentage of zona-free hamster ova penetrated continued to be lower than in ejaculates from the fertile boars. One of the two previously infertile boars consistently had a normal semen analysis. The only two observed manifestations of his reduced fertility were his zero conception rate and the limited ability of his sperm to penetrate zona-free hamster ova. In the second study, females were inseminated with equal numbers of sperm from two previously fertile males and the paternity of offspring determined at birth. The experiment was replicated with four combinations of six boars. A high correlation was observed between the percentage of offspring sired and the ability to penetrate zona-free hamster ova (R = .89). Neither morphology nor the ability of the sperm to undergo an acrosome reaction during in vitro incubation was correlated with fertility in the competitive mating situation. These results suggest the zona-free hamster ova bioassay can improve the in vitro fertility assessment of fresh boar semen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220405
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  • 216
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    Proteins of the acrosomal region in mouse sperm: Immunological probes reveal post-testicular modifications (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 21-37 
    Details
    ISSN: 0148-7280
    Keywords: monoclonal antibodies ; epididymal maturation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Due to the central role the acrosomal region plays in sperm-egg interactions, monoclonal antibodies (mAbs) were used to identify components of this domain in mouse sperm. Sev eral sperm proteins that localize specifically to the anterior acrosomal region are described here in terms of electrophoretic mobility, susceptibility to proteolytic degradation, and post-translational modification during epididymal transit. Six different mAbs were used, each recognizing a distinctive antigen (Ag) or set of Ags in cauda epididymal mouse sperm: a doublet of 185/200 Kd (M42 mAb); 150-160 Kd (M5 mAb); 105 Kd (W71 mAb); 21, 35, and 60 Kd (M41 mAb); 27 and 33 Kd (W33 mAb); and 57 and 86 Kd (W108 mAb). Previously reported work implicates two of these, M42 Ag and M5 Ag, as participants in sperm-zona interaction (Saling and Lakoski: Biol Reprod 33:527-536, 1985; Saling: Dev Biol 117:511-519, 1986; and Lakoski et al.: Biol Reprod 38:221-233, 1988).Recognition of some (M42, M5, W108), but not all (W33), of the Ags by their corre sponding mAbs was affected by sperm incubation with proteases (trypsin or collagenase). Evidence of post-translational modification during epididymal maturation was suggested by altered electrophoretic mobility of several of the Ags (M42, M5, W33, and W108) accompanying sperm transit from proximal to distal epididymis. Retention of sperm within the caput epididymis prevented structural alterations for the four proteins exam ined, indicating that spatial rather than temporal factors are critical for Ag modification in maturing mouse sperm.
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230301
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    Fertilization and development of mouse eggs injected under the zona pellucida with single spermatozoa treated to induce the acrosome reaction (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 233-243 
    Details
    ISSN: 0148-7280
    Keywords: microinjection ; acrosome reaction ; embryo development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mouse spermatozoa were capacitated and acrosome reacted by incubation for 30 min to 6 h in modified Tyrode's medium (T6) and in cGMP. The fertilization rates of eggs microin-jected with a spermatozoon from samples incubated for 30 min, 2 h, and 6 h in T6 and in cGMP were 36%, 34%, 29%, and 43%, respectively. These rates were not correlated to the percentage of acrosome-reacted spermatozoa identified after these treatments. The lack of association could be explained by the selection of an increased proportion of acrosomc-reacted spermatozoa actually used for microinjection, particularly in samples incubated for 30 min and 2 h in T6. Both acrosome-intact and acrosome-reacted spermatozoa were identified under the zona in the eggs which failed to fertilize. Fertilized eggs developed at very high rates to the blastocyst stage in vitro.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120230210
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    Influence of cumulus cell processes on oolemma permeability and lethality of isolated mouse oocytes cultured in Ca2+-free medium (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 245-253 
    Details
    ISSN: 0148-7280
    Keywords: zona pellucida ; cumulus cells ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cumulus cell processes remaining in the zona pellucida of mouse occytes mechanically isolated from the ovary have been indirectly visualized by labeling their actin microfilament core with rhodaminyl-phalloidin. If the isolation of the oocytes is performed in Ca2+-free medium, the preisence of such processes allows the entry into the cell of low molecular weight molecules (such as 5-6 carboxyfluorescein) and contributes to the death of the cell in such experimental conditions.Following dissolution of the zona pellucida (by enzymatic or acidic treatment) the oocyte is no longer permeable to small molecules and becomes resistant to Ca2+-free medium, probably as a consequence of the collapse of cumulus cell processes. The role of cumulus cell processes and gap junctions in the permeability of mechanically isolated ovarian oocytes is discussed.
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    Effects of follicle-stimulating hormone and ovarian steroids during vitro meiotic maturation on fertilization of rat oocytes (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 267-277 
    Details
    ISSN: 0148-7280
    Keywords: gonadotropins ; oocytes ; maturation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The present study examined the effects of gonadotropins and ovarian steroids during in vitro meiotic maturation of rat oocytes on their ability to undergo in vitro fertilization. Fully grown oocytes were isolated from antral follicles of immature rats and cultured as oocyte-cumulus cell complexes (OCC) under conditions in which completion of meiotic maturation occurs spontaneously. They were then exposed to spermatozoa under conditions in which oocytes matured in vivo exhibit high fertilization rates. Compared with oocytes from pregnant mare's serum gonadotropin (PMSG) or follicle-stimulating hormone (FSH)-treated rats, a simiiar proportion of the oocytes (〉80%) from untreated rats underwent germinal vesicle breakdown, but such oocytes had a lower rate of fertilization (70% vs. 20%). The presence of FSH during in vitro maturation restored the fertilization rate for oocytes from untreated rats, while a cytochrome P450 inhibitor, aminoglutethimide phosphate abolished this beneficial effect of FSH. The addition of progesterone during the in vitro maturation period duplicated the beneficial effect of FSH on fertilization rate of oocytes from untreated rats; oestradiol-17β was less effective in this regard, and 5α-dihydrotestosterone was ineffective. These findings indicate that FSH and progesterone, although having no apparent effect on nuclear maturation of the oocyte, play an important role during oocyte maturation in enabling normal fertilization to occur.
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    URL: http://dx.doi.org/10.1002/mrd.1120230304
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    Activation of Ca2+channels during the acrosome reaction of sea urchin sperm is inhibited by inhibitors of chymotrypsin-like proteases (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 255-266 
    Details
    ISSN: 0148-7280
    Keywords: protease ; acrosome reaction ; calcium channel ; sperm ; sea urchin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Probable participation of sperm protease in the acrosome reaction was investigated using several inhibitors and substrates. Among those examined, L-l-tosylamide-2-phenylethyl chloromethyl ketone (TPCK) and chymostatin, chymotrypsin inhibitors, p-nitrophenyl-p′-guanidinobenzoate (NPGB), a serine protease inhibitor, and N-benzoyl-L-tyrosine ethyl ester (BTEE), a chymotrypsin substrate, inhibited the egg jelly-induced acrosome reaction of Strongylocentrotus intermedius. TPCK and BTEE, however, did not inhibit the reaction caused by ionophores, A23187, or nigericin. To know the mechanism of inhibition by chymotrypsin inhibitors and substrates of the egg jelly-induced acrosome reaction, intraccllular Ca2+ concentration ([Ca2+]i) and pH (pHi) were measured with fura-2 and 2′,7′-bis (carboxy-ethyl)carboxyfluorescein (BCECF), respectively. Egg jelly caused increase of [Ca2+]i which was depressed by BTEE. Egg jelly also caused a transient rise of pHi, which was not depressed by BTEE. In the presence of verapamil, the acrosome reaction by egg jelly was significantly inhibited concomitant with depressed increase of [Ca2+]i. The rise of pHj was not depressed by verapamil. Thus, modes of action of BTEE and of verapamil are similar to each other. Bringing these findings together, the authors present a view that a chymotrypsin-like protease of sea urchin sperm activates verapamil-sensitive Ca2+ channels, which take part in the acrosome reaction.
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    Microtubule assembly is required for the formation of the pronuclei, nuclear lamin acquisition, and DNA synthesis during mouse, but not sea urchin, fertillization (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 309-322 
    Details
    ISSN: 0148-7280
    Keywords: pronuclear formation ; microtubules ; microfilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Microtubule assembly is required for the formation of the male and female pronuclei during mouse, but not sea urchin, fertilization. In mouse oocytes, 50 μM colcemid prevents the decondensation of the maternal meiotic chromosomes and of the incorporated sperm nucleus during in vitro fertilization. Nuclear lamins do not associate with either of the parental chromatin sets although peripherin, the PI nuclear peripheral antigen, appears on both. DN A synthesis docs not occur in these fertilized, colcemid-arrested oocytes. This effect is limited to the first hours after ovulation, since colcemid added 4-6 hours later no longer prevents pronuclear development, lamin acquisition, or DNA synthesis. Neither microtubule stabilization with 10 μM taxol nor microfilament inhibition with 10 μM cytochalasin D or 2.2 μg/ml lalrunculin A prevent these pronuclear events; these drugs will inhibit the apposition of the pronuclei at the egg center. In sea urchin eggs, colcemid or griseofulvin treatment doe? not result in the same effect and the male pronucleus forms with the attendant accumulation of the nuclear lamins. The differences in the requirement for microtubule assembly during pronucleus formation may be related to the cell cycle: In mice the sperm enters a meiotic cytoplasm, whereas in sea urchin eggs it enters an interphase cytoplasm. Refertilization of mitotic sea urchin eggs was performed to test the possibility that this phenomenon is related to whether the sperm enters a meiotic/mitotic cytoplasm or one at interphase; during refertilization at first mitosis, the incorporated sperm nucleus is unable to decondense and acquire lamins. These results indicate a requirement for microtubule assembly for the progression from meiosis to first interphase during mouse fertilization and suggest that the cytoskeleton is required for changes in nuclear architecture necessary during fertilization and the cell cycle.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120230308
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    Adrenergic stimulation of sea urchin sperm cells (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 291-302 
    Details
    ISSN: 0148-7280
    Keywords: noradrenrgic ; trifluoperazine ; verapamil ; calcium ; caffeine ; 8-Br-cAMP ; sperm motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The noradrenergic agonists norepinephrine and isoproterenol elicit greater stimulatory swim ming responses in sea urchin spermatozoa than epinephrine. The β-blocker atenolol induces an even greater motile rate, while the α-blocker phentolamine has only a moderate effect, it also causes a minimal reduction in the sperm cells' response to atenolpol. Caffeine increases the motility but to a lesser degree than 8-Br-cAMP. In drug interaction assays, both caffeine and 8-Br-cAMP depress the adrenergic effects. Agents that affect access of calcium to the flagellar apparatus (verapamil and trifluoperazine) depress the motility below the level of the controls when incubated separately with the sperm suspensions and counteract the stimulation due to atenolol. Adrenergic modulation of sperm motility thus appears to be both a calcium-dependent and a cyclic nucleotide-dependent process.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120240306
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    Devlopment of chimaeric two-cell mouse embryos produced by allogenic exchange of single nucleus from two- and eight-cell embryos (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 375-384 
    Details
    ISSN: 0148-7280
    Keywords: nuclear transfer ; cell allocation ; asynchronous embryos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Synchronous or asynchronous chimaeras were produced by transplanting a single nucleus of two- and eight-cell embryos from CD-lxCD-1 or BALB/CxBALB/C albino strains into one enucleated blastomere of a late Fl (C57/BLxCBA) × Fl two-cell embryo. The cytoplasmic volume of the blastomere was reduced in some instances by 50%. These chimaeric embryos were cultured in vitro and transferred to pseudopregnant recipients. The distribution of each component to the pups and to the day-10 embryos after transfer to recipients was determined by examining their coat color and by glucose phosphate isomerase analysis, respectively. The contribution of progeny of the nuclear-transplanted cell with nonreduced cytoplast to the pups was 83% when synchronous; this proportion decreased to 43% when asynchronous because the progeny tended to migrate to the trophoblast and/or to the primitive endoderm. When the recipient cytoplast was reduced by 50%, the contribution of the nuclear-transplanted cell progeny to the pups was 79% when synchronous and 80% when asynchronous. This shows that allogenic exchange of a single nucleus at the two-cell stage by nuclear transfer is an effective procedure for producing highly asynchronous mouse chimaeras and suggests that larger and advanced blastomeres tend to be excluded from the inner cell mass of the embryo, but smaller, advanced blastomeres do not.
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    URL: http://dx.doi.org/10.1002/mrd.1120240404
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    Effect of sulfated glycoconjugates on capacitation and the acrosome reaction of bovine and hamster spermatozoa (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 403-413 
    Details
    ISSN: 0148-7280
    Keywords: heparin ; fertilization ; dextran sulfate ; fucose sulfate glycoconjugate ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effects of sulfated glycoconjugates on the preparation of mammalian sperm for fertilization were investigated. The three sulfated glycoconjugates tested were heparin, dextran sulfate, and the fucose sulfate glycoconjugate (FSG) from the sea urchin egg jelly coat. In vivo, FSG induces the acrosome reaction in sea urchin sperm. Bovine sperm were found to be capacitated by heparin and FSG as judged both by ability of lysophosphatidylcholine (LC) to induce an acrosome reaction and by ability to fertilize bovine oocytes in vitro. The mechanism by which heparin or FSG capacitated bovine sperm appeared similar, since glucose inhibited capacitation by both glycoconjugates. In contrast to effects on bovine sperm, heparin and FSG induced the acrosome reaction in capacitated hamster sperm. When hamster sperm were incubated under noncapacitating conditions, heparin had no effect on capacitation or the acrosome reaction. Three molecular weights (MW) of dextran sulfate (5,000, 8,000, 500,000) were found to capacitate bovine sperm as judged by the ability of LC to induce an acrosome reaction. Whereas bovine sperm incubated with 5,000 or 8,000 M W dextran sulfate fertilized more bovine oocytes than control sperm (P 〈0.05), sperm treated with 500,000 M W dextran sulfate failed to penetrate oocytes. The high-MW dextran sulfate appeared to interact with the zona pellucida and/or sperm to prevent sperm binding. Results suggest that sulfated glycoconjugates may prepare sperm for fertilization across a wide range of species.
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    URL: http://dx.doi.org/10.1002/mrd.1120240407
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    Effects of transglutaminase substrates and inhibitors on the motility of demembranated reactivated spermatozoa (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 179-192 
    Details
    ISSN: 0148-7280
    Keywords: sperm motility ; axonemes ; microtubule sliding ; modeled spermatozoa ; cross linking ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The 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 of 3H-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 activity in sperm motility.
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    URL: http://dx.doi.org/10.1002/mrd.1120220206
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    Role of glutathione peroxidase in protecting mammalian spermatozoa from loss of motility caused by spontaneous lipid peroxidation (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 77-90 
    Details
    ISSN: 0148-7280
    Keywords: lipid peroxidation ; sperm H2O2 toxicity ; sperm glutathione peroxidase ; sperm glutathione ; sperm ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mouse and human spermatozoa, but not rabbit spermatozoa, have long been known to be sensitive to loss of motility induced by exogenous H2O2. Recent work has shown that loss of sperm motility in these species correlates with the extent of spontaneous lipid peroxidation. In this study, the effect of H2O2 on this reaction in sperm of the three species was investi gated. The rate of spontaneous lipid peroxidation in mouse and human sperm is markedly enhanced in the presence of 1-5 mM H2O2, while the rate in rabbit sperm is unaffected by H2O2. The enhancement of lipid peroxidation, the rate of reaction of H2O2 with the cells, the activity of sperm glutathione peroxidase, and the endogenous glutathione content are highest in mouse sperm, intermediate in human sperm, and very low in rabbit sperm. Inac tivation of glutathione peroxidase occurs in the presence of H2O2 due to complete conver sion of endogenous glutathione to GSSG: No GSH is available as electron donor substrate to the peroxidase. Inactivation of glutathione peroxidase by the inhibitor mercaptosucci nate has the same effect on rate of lipid peroxidation and loss of motility in mouse and human sperm as does H2O2. This implies that H2O2 by itself at 1-5 mM is not intrinsically toxic to the cells. With merceptosuccinate, the endogenous glutathione is present as GSH in mouse and human sperm, indicating that the redox state of intracellular glutathione by itself plays little role in protecting the cell against spontaneous lipid peroxidation. Mouse and human sperm also have high rates of superoxide production. We conclude that the key intermediate in spontaneous lipid peroxidation is lipid hydroperoxide generated by a chain reaction initiated by and utilizing superoxide. Removal of this hydroperoxide by gluta thione peroxidase protects these sperm against peroxidation; inactivation of the peroxidase allows lipid hydroperoxide to increase and so increases the peroxidation rate. Rabbit sperm have low rates of superoxide reaction due to high activity of their superoxide dismutase; lack of endogenous glutathione and low peroxidase activity does not affect their rate or lipid peroxidation. As a result, these sperm are not affected by either H2O2 or mercapto-succinate. These results lead us to postulate a mechanism for spontaneous lipid peroxida tion in mammalian sperm which involves reaction of lipid hydroperoxide and O2 as the rate-determining step.
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    Development in vitro of investment-free marsupial embryos during cleavage and early blastocyst formation (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 399-413 
    Details
    ISSN: 0148-7280
    Keywords: marsupial ; in vitro blastocyst ; investment-free embryos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Twenty embryos at the cleavage-arrested four-cell stage of the brown antechinus, Antechinus stuartii, were used to develop a method to obtain investment-free embryos by incubation at 35°C in 2.5% pancreatin, 0.05% trypsin, and 0.05% pronase. Control intact embryos and the investment-free embryos were incubated in Dulbccco's Modified Eagle's Medium with high glucose and 10% foetal calf serum in 5% CO2 in air at 35°C for 48 h. Release of embryos from the investments (shell, muooid, and zona pcllucida) took 4-4½ h in pancreatin, 6 h in trypsin, and 55 min to 1¼ h in pronase. Embryonic survival in vitro was best following pronase digestion. Pronase concentrations of 0.05%, 0.1 %, 0.25%, 0.5%, and 1.0% were used to free one-to 16-cell stage embryos of brown antechinus and the stripe-faced dunnart, Sminthopsis macroura. from their investments. Postincubation survival and development of embryos in vitro was best using between 0.05% and 0.25% pronase. Blastomeres in both intact and investment-free embryos shared similar characteristics during cleavage and blastocyst formation. The combined effect of these characteristics was that in intact embryos, no morula was formed, and the blastocyst developed, when cell numbers were high enough (about 32 cells), as a unilaminar structure flattened against the zona pellucida and without an inner cell mass. In investment-free embryos, the blastomeres dispersed over the base of the culture vessel. The investments were necessary to confine the blastomeres, to provide a surface for blastomere flattening, and to allow normal cellular associations to develop.
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    Glycerylphosphorylcholine diesterase activity of uterine fluid in conditions inducing secondary sex ratio change in the rat (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 415-420 
    Details
    ISSN: 0148-7280
    Keywords: sex ratio ; uterine enzyme ; dietary cation ; stress ; glycerylphosphorylcholine diesterase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Food restriction or decreasing the ratio of [Na+, K+] to Ca++, Mg++J in the diet of female rats before conception favoured the production of female offspring. Seven days of food deprivation decreased uterine fluid GPC diesterase activity in female rats, whereas long-term food restriction (21 days), rather than decreasing the enzyme activity, apparently stimulated it. Dietary Ca and Mg supplementation, likewise, produced significant decrease in GPC di esterase activity. A significantly positive correlation was observed between the levels of uterine GPC diesterase and secondary sex ratio change, which indicates that these dietary techniques of sex-ratio manipulation may modulate the uterine fluid GPC diesterase activity and influence sex determination in utero.
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    URL: http://dx.doi.org/10.1002/mrd.1120230406
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    Primordial germ cell development in cultures of dispersed central disks of stage X chick blastoderms (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 421-427 
    Details
    ISSN: 0148-7280
    Keywords: PGCS (primordial germ cells) ; stage X ; chick blastoderm ; cell aggregates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Central disk fragments cut from stage X chick blastoderms were dispersed and cultured on glass coverslips. After 48 hr of incubation the cultures showed various degrees of organization into three-layered aggregates in which no axis development was observed. Primordial germ cells (PGCs) were detected in ail cultures. The number of PGCs was found to be correlated to the initial cell concentration in the suspension. By regression analysis it was found that in cultures initiated from 10 central disks or more, the mean number of PGCs per fragment was constant and matched the number of PGCs found for intact control central disks incubated for the same length of time. It appears that in cultures of stage X, the morphologic expression of PGCs is related to the level of differentiation and organization of the somatic cells in the culture, which, in turn, is dependent on the initial concentration of cells in the culture.
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    Membrane specializations associated with the acrosomal complex of sea urchin sperm as revealed by immunocytochemistry and freeze fracture replication (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 429-440 
    Details
    ISSN: 0148-7280
    Keywords: acrosome reaction ; intraumembranous particles ; monoclonal antibody detection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Observations, employing freeze fracture replication and electron microscopic imrnunochemis-try, have been carried out to determine structural correlations of the plasma membrane domain occupied by a 210 kDa protein involved in the acrosomal reaction of sea urchin sperm and recognized by the monoclonal antibody, J10/14 (Trimmer et al: Cell 40:697-703, 1985; Proceedings of the National Academy of Sciences of the United States of America 83: 9055-9059, 1986). Immunogold-J10/14 staining of acrosorne-intact sperm was intense along the flagellum and a narrow collar just posterior to the sperm apex that surrounded the acrosomal complex (acrosomal vesicle and subjacent anterior nuclear fossa containing g-actin). Counts of gold particles revealed a density (average number of particles/μm2 of surface area) eightfold greater along the plasma membrane associated with the acrosomal complex than membrane delimiting the remainder of the sperm head. The collar of J10/14 staining was isomorphic with a dense aggregation of intramembranous particles in the P-face of the plasma membrane and a thin cytoplasmic region that surrounded the acrosomal complex. In acrosomc-reacted sperm, intense J10/14 staining was distributed along the flagellum and sperm head; prominent anterior staining was not apparent in all specimens. The density of gold particles associated with plasma membrane delimiting components of the former acrosomal complex, nucleus and mitochondrion, as well as the total average number of particles along the entire sperm surface, were increased in sperm acrosome-reacted with A-23187. Concomitant with this change in staining was the disappearance/reduction of the collars of intramembranous particles and cytoplasm. These observations indicate that plasma membrane components (210 kDa protein and intramembranous particles) and the collar of cytoplasm which are associated with the acrosomal complex are functionally, as well as structurally related. Analyses of particle density distributions along acrosome- and non-acrosome-reacted sperm suggest that the different staining patterns observed may be brought about by the recognition of cryptic sites at the time of the acrosomal reaction.
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    Effects of semen preservation on boar spermatozoa head membranes (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 441-449 
    Details
    ISSN: 0148-7280
    Keywords: boar ; spermatozoa ; membrane fluidity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Head plasma membranes were isolated from the sperm-rich fraction of boar semen and from sperm-rich semen that had been subjected to three commercial preservation processes: Ex tended for fresh insemination (extended), prepared for freezing but not frozen (cooled), and stored frozen for 3-5 weeks (frozen-thawed). Fluorescence polarization was used to determine fluidity of the membranes of all samples for 160 min at 25°C and also for membranes from the sperm-rich and extended semen during cooling and reheating (25 to 5 to 40°C, 0.4°C/min). Head plasma membranes from extended semen were initially more fluid than from other sources (P 〈 0.05). Fluidity of head membranes from all sources decreased at 25°C, but the rate of decrease was significantly lower for membranes from cooled and lower again for membranes from frozen-thawed semen. Cooling to 5°C reduced the rate of fluidity change for plasma membranes from the spernvrich fraction, while heating over 30°C caused a signifi cantly greater decrease. The presence of Ca++ (10 mM) lowered the fluidity of the head plasma membranes from sperm-rich and extended semen over time at 25°C but did not affect the membranes from the cooled or frozen-thawed semen. The change in head plasma membrane fluidity at 25°C may reflect the dynamic nature of spermatozoa membranes prior to fertilization. Extenders, preservation processes and temperature changes have a strong influence on head plasma membrane fluidity and therefore the molecular organization of this membrane.
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    URL: http://dx.doi.org/10.1002/mrd.1120230409
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    Lipid peroxidation in human spermatozoa as relatd to midpiece abnormalities and motility (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 127-134 
    Details
    ISSN: 0148-7280
    Keywords: lipid peroxidation ; human sperm motility ; morphology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The formation of malondialdehyde (MDA), a product of lipid peroxidation (LPO), was measured in human spermatozoa from 27 subjects with normal sperm characteristics. Peroxidation of lipids in washed spermatozoa was induced by catalytic amounts of ferrous ions and ascorbate and malondiaidehyde dctermint-d by thiobarbituric method. MDA formation varied considerably from one sample to another. The studied population showed a strong correlation between lipid peroxidation potential (amount of MDA formed by 108 spermatozoa after 1 hour of incubation) and 1) initial motility r = -0.623, P = 0.001; and 2) morphologic abnormalities of the midpiece r = 0.405, P = 0.05. These results suggest that poor motility is linked with membrane fragility and that spermatozoa with midpiece abnormalities probably have membrane and/or cytoplasmic antiperoxidant system defects. Because LPO potential is related to the two most important characteristics of fertility, it seems possible that it has the potential to become a good biochemical index of semen quality.
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    Trout sertoli cells and germ cells in primary culture: I. Morphological and ultrastructural study (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 151-169 
    Details
    ISSN: 0148-7280
    Keywords: teleost ; testis ; cell culture ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In order to characterize trout Sertoli cells and germ cells obtained after testis dissociation and cell separation, we have studied their morphology, ultrastructure, survival, and ability to express differentiated activities in primary cultures. After dissociation, the fine structure of Sertoli cells does not differ from that observed in situ and only minor changes are shown for at least 13 days. Until they are flattened in a monolayer, they keep the ability to retain germ cells on their surface. When flattened, some of them are able to divide. At the opposite of meiotic germ cells, spermatogonia can develop independently of Sertoli cells. They are able to proliferate during at least 10 days. Spermatocytes and spermatids are obtained as single cells and multinucleated giant cells (symplasts). In the absence of somatic cells, their maximal viability is approximately 5 days, whereas spermatocytes adhering to Sertoli cells can survive at least 10-12 days, provided trout lipoproteins are present. Spermatocytes are able to differentiate to spermatids, although this process is impaired for some ceils. The adhesion of spermatogonia and spermatocytes to Sertoli cells is specific, mediated by desmosome-like junctions and favored by lipoproteins. These data are compared to what is known in mammals and in amphibians.
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    Catalase activity in human spermatozoa and seminal plasma (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 185-196 
    Details
    ISSN: 0148-7280
    Keywords: free radicals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Catalase activity was determined in human semen by measuring the oxygen burst with a Clark electrode, after H2O2 addition. Significant catalase activities (mean ± SD) were found in migrated, motile spermatozoa (44 ± 17 nmoles O2/min/108 cells) and in seminal plasma of normozoospermic men (129 ± 59 nmoles O2/min/ml). It has been demonstrated that seminal catalase originated from prostate; however, its activity was not correlated with the usual prostatic markers (such as citric acid and zinc). Our data suggest a multiglandular function secreted by this organ. The catalase activities measured in seminal samples from asthenozo-ospermic, infertile men were found lower than those from normozoospermic subjects. The understanding of the relative contribution of the different enzyme systems against O2 toxicity (superoxide dismutase, catalase, glutathione peroxidase) seem to be a priority area of research to understand disturbances of sperm function.
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    Morphology of immature bovine oocytes (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 197-204 
    Details
    ISSN: 0148-7280
    Keywords: cow ; ultrastructure ; cumulus cell processes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine cumulus oocyte complexes (COCs) as used for in vitro maturation and fertilization can be classified into different categories by light microscopical inspection. We have distinguished four categories based on compactness and transparency of the cumulus investment and homogeneity and transparency of the ooplasm. The four categories were studied for their morphological characteristics at the ultrastructural level and for their developing capacity in an in vitro maturation system. In categories 1 and 2 oocytes, organelles were evenly distributed. In categories 3 and 4, oocytes organelles were clustered and the distribution of the organelles mimicked the characteristics of oocytes during final maturation. Cumulus cell process endings penetrated the cortex of the oocyte or were located superficial to the cortex of the oocyte. In category 1 oocytes, most of the process endings penetrated the cortex. In category 4 oocytes, most of the process endings did not penetrate. In categories 2 and 3 oocytes, both forms of process endings did occur.After in vitro maturation, only category 4 oocytes showed a decreased developing capacity. Categories 1-3 oocytes showed equal developing capacity in an in vitro maturation system.
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120240301
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    Role of spermatozeugmata in the spawning ecology of the brooding oyster Ostrea edulis (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 219-228 
    Details
    ISSN: 0148-7280
    Keywords: bivalvia ; spermatozeugma ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ostrea edulis spawns spermatozeugmata, each composed of radially arrayed sperm cells attached by an extracellular matrix (ECM) to a core of acellular vesicles. The acellular vesicles arc formed from excess nuclear and plasma membranes produced during spermatid condensation, and the ECM is topologically restricted to the interstices between acellular vesicles and sperm heads, being absent from the flagellar surface. When released into seawater, spermatozeugmata retain their structural integrity for varying periods (up to 24 hours) and become demersally distributed in still water. The flagella activate, initially beating in a non-synchronized, languid manner; however, both the tempo and amplitude of the flagellar action gradually increase to resemble that of typical ‘primitive’ sperm once the cells are released from the spermatozeugma. This increase in flagellar activity and subsequent gamete release coincide with an erosion of the ECM and suggest that the ECM may modulate sperm motility in addition to adhering the cells to the spermatozeugma. Sperm are capable of fertilizing eggs only after dissociating from the spermatozeugma. The net effect of spermatozeugma formation in Ostrea edulis may be the retention of viable sperm in high concentrations at the benthic/ water column interface for prolonged periods after spawning, at least in low current regimes. Unfertilized O. edulis eggs are also concentrated at this location, in the inhalent chambers of female oysters. Spermatozeugmata are entrained by the inhalent current of females and carried into the brood chamber where fertilization occurs. The Ostrea edulis spermatozeugma likely functions as an efficient sperm transfer mechanism if two conditions are met: 1) eggs are retained as broods within benthic females, 2) egg masses are at intermediate distances from spawning males.
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    The plasama membrane of Xenopus laevis spermatozoon (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 237-246 
    Details
    ISSN: 0148-7280
    Keywords: sperm ; lectin ; turbidimetry ; freeze-fracture ; deep-etching ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Xenopus laevis sperm plasma membrane ultrastructure has been studied by means of freeze-fracture, deep-etching, and lectin-gold binding. Xenopus spermatozoa differ from those of other species in that their plasma membrane does not exhibit topographical domains. In fact, no geometric arrangement or characteristic array of particles is present on fractured plasma membrane. Fractures rarely occur in acrosomal or nuclear membranes. Wheat germ agglutinin receptors are distributed homogeneously, on the plasma membrane of the sperm head and tail.
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    Calcium-binding proteins of boar spermatozoan plasma membranes: Identification and partial characterization (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 49-60 
    Details
    ISSN: 0148-7280
    Keywords: sperm ; plasma membranes ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Calcium-binding proteins (CBPs) of boar spermatozoa and boar seminal plasma were identified by using a 45Ca overlay technique to detect these proteins on transblots of PAGE-separated proteins. A single CBP (Mr ∼ 300 kDa) was detected in seminal plasma. This protein binds specifically to the plasma membrane overlying the principal segment and is removed from sperm during capacitation. The protein was purified for further charac terization by anion exchange chromatography and gel filtration. In addition, six major proteins (30, 35, 38, 42, 52, and 66 kDa) which do not originate from accessory gland secretions were found to be strongly associated with the plasma membrane. Most of these proteins are not integral to the membrane and appear to develop an association with the plasma membrane during cpididymai maturation. Similarly, calmodulin-binding proteins appear to develop strong associations with the plasma membrane during epididymal transit.
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    Sperm morphology and storage in the female reproductive tract of the fat-tailed dunnart, Sminthopsis crassicaudata (Marsupialia: Dasyuridae) (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 61-75 
    Details
    ISSN: 0148-7280
    Keywords: dunnart ; spermatozoa ; isthmus ; epithelium ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A study of spermatozoa in the isthmus of the oviduct and of the surrounding epithelial cells in the dasyurid marsupial, Sminthopsis crassicaudata, was carried out. At least 10% of the ejaculated spermatozoa probably populate the isthmus region, where many come to reside in crypts until around the time of ovulation. Ultrastructural observations of spermatozoa in this region indicated that they had intact acrosomes and were identical in their morphology with those in the cauda epididymidis. After ovulation spermatozoa rapidly disappeared, some of which may be phagocytosed by the cells lining the crypts. These epithelial cells were also found to have many large, electron-dense granules at the time of sperm storage, but the contents did not appear to be released until the zygotes passed along the tract. The secretory activity of these cells may thus relate more to the production of the shell membrane that comes to surround the zygote than to the cells performing a nutritive or protective function for the spermatozoa during their period of storage within the female reproductive tract.
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    Characterization of cell surface polypeptides of unfertilized, fertilized, and protease-treated zona-free mouse eggs (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 91-101 
    Details
    ISSN: 0148-7280
    Keywords: fertilization ; zona-free egg ; membrane polypeptides ; radioiodination ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The polypeptide composition of unfertilized, fertilized, and protease-treated zona-free mouse eggs was evaluated in this study. Zona-free eggs were radioiodinated by an Iodogen-catalyzed reaction. Light microscopic autoradiography of egg sections revealed that labeling was restricted to the cell surface. Labeled eggs were solubilized, and cell surface polypeptides were identified by one-dimensional SDS polyacrylamide gel electro-phoresis and autoradiography. The unfertilized egg demonstrated 8-10 peptides that incorporated125I, with major bands observed at approximately 145-150, 94, and 23 kilo-daltons (kD). Zona-free eggs fertilized in vitro and then radiolabeled demonstrated several new bands in comparison to unfertilized eggs, with a major band appearing at approxi mately 36 kD. Treatment of radiolabeled unfertilized eggs with either trypsin or chymo-trypsin (1 mg/ml for 5-20 min) caused enzyme-specific modifications in labeled polypep tides. Trypsin (T) treatment resulted in time-dependant modification of the three major peptides at 145-150,94, and 23 kD. Chymotrypsin (CT) treatment, in contrast, was asso ciated with loss or modification of the 94 kD band, with no apparent effect on either the 145-150 or 23 kD band. Taken together with previous data indicating that T or CT egg treatment interferes with sperm-egg attachment and fusion (Boldt et al.: Biol Reprod 39:19-27, 1988), these results suggest a possible role for the 94 kD protein in sperm-egg interaction.
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    URL: http://dx.doi.org/10.1002/mrd.1120230109
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    Identification, isolation, and properties of a plasma membrane protein involved in the adhesion of boar sperm to the porcine zona pellucida (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 103-118 
    Details
    ISSN: 0148-7280
    Keywords: gamete-interactions ; fertilization ; mammals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Boar sperm plasma membranes contain an integral protein (Mr 55 kDa) that apparently functions in the adhesion of sperm to the zona pellucida (Peterson and Hunt: J Cell Biol 105:170a, 1987.) In experiments described in this report, the protein is identified after additional steps of purification involving lectin affinity chromatography and preparative PAGE. An active form of the adhesion protein (APz) develops or becomes first exposed in the corpus epididymis and is fully active in the cauda epididymis; a significant portion of this conformationally labile protein, while integral to the plasma membrane, cannot be solubilized by nonionic detergents and may be associated with the membrane skeleton. APz does not exhibit enzymatic properties thought possibly to be involved in sperm-zona interaction in this and other species. Galactosyltransferase substrates and inhibitors and anliproteases including soybean trypsin inhibitor, pepstatin, leupeptin, and p-aminoben-zamidine failed to block sperm from binding to porcine eggs. Boar sperm proacrosin and antiproacrosin antibody failed to inhibit sperm-egg binding. When plasma membranes or fractions containing APz that bind to dextran sulfate agarose were chromatographed on L-fucose agarose, a sugar which binds proacrosin, plasma membrane proteins that bound to the column failed to absorb anti-APz antibody, Anti-APz was absorbed by fractions that did not contain proacrosin. These data indicate that APz is not proacrosin. Since anti-APz monovalcnt antibody raised from whole cauda or corpus sperm plasma membranes or from chromatographic fractions containing APz completely block capacitated sperm from binding to eggs, and since the ability of this antibody to be absorbed develops as sperm become capable of binding to eggs, we view AP, to be the major and perhaps only plasma membrane protein involved in the adhesion of capacitated boar sperm to eggs prior to the acrosome reaction.
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    In vitro fertilization in the sheep: Effect of elevated calcium concentration at insemination (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 119-125 
    Details
    ISSN: 0148-7280
    Keywords: ovine ; in vitro fertilization ; calcium ; semen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Oocytcs (n = 273), collected from superovulated ewes, were inseminated with in vitro capacitated spermatozoa from four rams [Crozet et al., 1987]. In each experiment, paral lel insemination was performed using aliquants from a single ejaculate in either our stan-dard fertilization medium DM-H-SS (a modification of Bracken's defined medium, buffered with HEPES and containing 20% v/v sheep serum) or in the same medium supplemented with calcium lactate (DM-H-SS + Ca). The measured total calcium con centrations were Ca++T = 2.74 mM in DM-H-SS medium and Ca++T = 8.74 mM in DM-H-SS + Ca; the ratio of free to total calcium in DM-H-SS was Ca++F/Ca++T = 0.85. Fertilization was assessed at 17 hours postinsemination.Variations in the ejaculates were observed for each of the four rams tested. When DM-H-SS + Ca was used, the percentages of fertilized (75% vs. 50%) and monospermic (58% vs. 41%) eggs were significantly enhanced compared with use of DM-H-SS. No improve ment was observed in control medium DM-H-SS + lac containing neutralized lactic acid. Supplementing the fertilization medium with calcium had no apparent effect on the inci dence of polyspermy.These experiments show that the fertilization rate achievable in vitro by individual ejaculates from various rams can be increased by raising the calcium concentration in the fertilization medium to a value much higher than that present in tuba! fluids from estrous ewes. Extended incubation in such a high calcium concentration is unnecessary for in vitro capacitation of ram spermatozoa.
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230201
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    Preimplantation embryo development and serum steroid levels in immature rats induced to ovulate or superovulate with pregnant mares' serum gonadotropin injection or follicle-stimulating hormone infusions (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 127-138 
    Details
    ISSN: 0148-7280
    Keywords: embryo development ; superovulation ; PMSG ; FSH ; steroids ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Follicular stimulation protocols using pregnant mares' serum gonadotropin (PMSG) or a follicle-stimulating hormone (FSH) preparation were compared to evaluate the yield and quality of embryos obtained from immature rats. Rats received a superovulatory dose of PMSG (401U), a nonsuperovulatory dose of the same gonadotrophin (4 IU), or a continu ous s.c. infusion over a 72-h period with a purified FSH preparation containing an opti mum ratio of luteinizing hormone (LH): FSH (FSH-hCG). The females were caged with fertile males on the evening of the 3rd day of gonadotropin treatment and scored for the occurrence of mating on the next morning; subgroups were killed on days 1-4 of preg-nancy. High fertilization rates were observed in rats treated with 4 IU PMSG (84.1%) and in rats infused with FSH-hCG (91.0%); however, a much lower fertilization rate was observed following treatment with 40 IU PMSG (41.5%). From median ovulation rates of 9 and 79 in rats treated with 4 IU PMSG and in rats infused with FSH-hCG, medians of 8 and 69 embryos, respectively, were recovered from reproductive tracts flushed on day 4 of pregnancy, from which 75% were morulae or blastocysts; in contrast, from a median ovu lation rate of 42.5, a median of only 12 embryos was recovered on day 3 of pregnancy following superovulation with 40 IU PMSG of which 80% were degenerate ova. Serum steroid profiles during the first 4 days of pregnancy differed significantly among treatment groups, the major differences being in substantially elevated levels of estradiol and andro-gens on days 1-3 in rats receiving the high (40 IU) dose of PMSG. Levels of these steroids in rats superovulated with the FSH-hCG infusion regimen were only marginally elevated above levels observed in rats treated with the low (4 IU) nonsuperovulatory dose of PMSG. Consistent with high ovulation rates, serum progesterone levels rose to considera bly higher levels during the period in both superovulated groups than in animals receiving the low, nonsuperovulatory dose of PMSG. This work describes a novel method to superovulate rate (FSH-hCG) leading to high yields of normally developing embryos at all preimplantation stages and illustrates the close association between high yield of emyryos and low levels of circulating andorgens and estradiol-17β during the preimplantation period.
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    A consistently successful procedure for in vitro fertilization of golden hamster eggs (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 139-158 
    Details
    ISSN: 0148-7280
    Keywords: IVF ; sperm motility ; 2-cell embryos ; culture media ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Complete details are described for the first time of the procedures used in the author's laboratory for obtaining in vitro fertilization (IVF) of golden hamster eggs leading to the first cleavage division. These IVF procedures have been developed during the past 20 years and are very reproducible: IVF of at least 75% of eggs is routinely achieved, and on average 65% of inseminated eggs undergo the first cleavage division in vitro. These results can easily be obtained by inexperienced investigators. The ease and reproducibility of the hamster IVF procedures make them very suitable for studies of sperm:egg interaction and associated events. Studies in the author's laboratory have included analysis of sperm fertilizing ability under chemically defined conditions, the presence of sperm acrosome reaction stimulating factors in the egg investments, maturation of oocytes in vitro, the block to polyspermy, and the contribution of egg aging to fertilization anomalies. In addition, the motility of hamster sperm under chemically defined conditions is used in a routine screening protocol for detecting contaminants in the culture milieu. Golden hamster gametes of Ter several distinct advantages for IVF studies, including the large size of the sperm acrosome, the persistence of the very large sperm tail in the ooplasm for many hours following fertilization, and the translucence of the ooplasm, which facilitates observation of the sperm tail and pronuclei. The female golden hamster exhibits a regular 4 day estrous cycle, with distinctive indications of estrus and postestrus phases. Because of the advantages of using the golden hamster, the procedures described in this report may be useful to other investigators wishing to conduct research using IVF. Essentially the same IVF procedures can be used with monkey and bovine gametes.
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    Capacitation of hamster spermatozoa with the divalent cation chelators D-penicillamine, L-histidine, and L-cysteine in a protein-free culture medium (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 159-170 
    Details
    ISSN: 0148-7280
    Keywords: sperm capacitation ; zinc ; egg penetration ; in vitro ; chemically-defined culture medium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: By using a chemically defined (protein-free) culture medium that supports sperm viability but not capacitation or the acrosome reaction, we have determined that hamster spermatozoa can be chemically capacitated in vitro by the divalent cation chelators D-penicilla-mine, L-histidine, and L-cysteine in the absence of bovine serum albumin (BSA). Washed cauda epididymal spermatozoa were preincubated (1-2 × 106 sperm/ml) for 3, 4, or 6 hr at 37°C in 5% CO2 in air. The basic culture medium used for sperm preincubation and for sperm:egg coincubation was a modified Tyrode's solution (protein-free) containing 10 mM sodium lactate, 100 μM sodium pyruvate, and 1.0 mg/ml polyvinylalcohol (TLP-PVA). Sperm viability was maintained in all preincubation and coincubation media with PHE (20 μM D-penicillamine, 100 μM hypotaurine, and 1.0 μM epinephrine). The low control sperm preincubation medium consisted of TLP-PVA. In some cases the high control preincubation medium also contained 3 mg/ml BSA (TALP-PVA). The experimental preincubation medium was TLP-PVA with additional D-penicillamine (125 or 500 μM), or L-histidine (10, 100, or 1,000 μM) or L-cysteine (25, 75, or 125 μM). After preincubation, sperm were coincubated (2 × 104 sperm/ml) with cumulus-free hamster eggs in TALP-PVA ± additional D-penicillamine, L-histidine, or L-cysteine for 1.5 hr, fixed, and evaluated for percent egg penetration as an index of sperm capacitation. The results demonstrate that hamster spermatozoa can be chemically capacitated in vitro with D-penicillamine (500 μM: range of mean penetration values, 53.6%-84.3%), L-histidine (100 μM: range of mean values, 24.8%-56.3%) or L-cysteine (75 μM: 51.3%) in the absence of exogenous protein.
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    URL: http://dx.doi.org/10.1002/mrd.1120230203
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    Direct contact is required between serum albumin and hamster spermatozoa for capacitation in vitro (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 171-180 
    Details
    ISSN: 0148-7280
    Keywords: acrosome reaction ; dialysis membrane ; direct or indirect incubation ; BSA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A dialysis unit was used to test whether direct physical contact between serum albumin and hamster spermatozoa is required for capacitation and/or the acrosome reaction. Sperm and bovine serum albumin (BSA) were incubated cither together (direct incubation) or separated by a dialysis membrane (indirect incubation). Sperm viability was supported with “sperm motility factors” (hypotaurine and epinephrine) and polyvinylalcohol (PVA). Spermatozoa became capacitated and underwent acrosome reactions when directly incubated in medium containing BSA (TALP-PVA), but did not undergo acrosome reactions when indirectly incubated with BSA (medium TLP-PVA). When sperm were first incubated for 4 hr indirectly with BSA, followed by 4 hr direct incubation with BSA, capacitation did not occur during indirect incubation. These findings indicate that an “intimate association” is necessary between serum albumin and spermatozoa to support capacitation under in vitro incubation conditions. The data are consistent with the concept of direct transfer of compounds from sperm to albumin and/or vice versa during sperm capacitation.
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    URL: http://dx.doi.org/10.1002/mrd.1120230204
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    Morphogenesis of the decapitated and decaudated sperm defect in two brothers (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 181-188 
    Details
    ISSN: 0148-7280
    Keywords: human spermatozoa ; male infertility ; decapitated ; decaudated ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The “decapitated sperm” defect, found in both of two sterile brothers, may be assumed to have a genetic origin. The present material suggests that the term “decapitated spermatozoa” is not exact, because detached heads and tails were found in the brothers' ejaculate that could be regarded as “decapitated tails” and “decaudated heads.” The present report describes frequent, more or less advanced stages of detachment. Both heads and tails showed a normal structure in which only the postnuclear region was deficient, lacking basal plate and implantation fossa. A break at a different level of the midpiece, and therefore three kinds of separation, were observed. The defect, according to the present research, must originate in the testicular region, whereas the detachment occurs in the epididymis.
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    URL: http://dx.doi.org/10.1002/mrd.1120230205
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    Gamete membrane fusion in hamster spermatozoa with reacted equatorial segment (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 203-213 
    Details
    ISSN: 0148-7280
    Keywords: acrosome reaction ; plasma membrane ; vesiculation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mammalian spermatozoa must undergo many changes to be able to fertilize the oocyte. One of these changes, the acrosome reaction, has been established as a requisite for gamete membrane fusion to occur; it consists of the fusion and vesiculation of the sperm plasma membrane with the outer acrosomal membrane of the principal segment of the acrosome. Reaction of the equatorial segment has occasionally been observed. The objective of the present work was to determine whether the presence of the sperm plasma membrane over the equatorial segment is necessary for gamete membrane fusion to occur.Golden hamster spermatozoa were capacitated in vitro in TAPL 10K, and the maximum possible percentage of acrosome reaction was determined at 82.79% + 1.69% SD (P = 0.27; r = 0.21). Ultrastructural studies showed that 93.6% of the reacted spermatozoa in this population had their principal and equatorial segments reacted. The fertilizing ability of these spermatozoa was assayed using zona-free hamster oocytes. The percentage of fertilized ova obtained was 98.8% (308/312). Ultrastructural studies snowed the presence of spermatozoa with reacted equatorial segment inside the cytoplasm of immature oocytes. The evidence presented in this work demonstrates that the plasma membrane of spermatozoa with reacted equatorial segment retains its ability to fuse with the oocyte.
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    URL: http://dx.doi.org/10.1002/mrd.1120230207
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    Influence of serum and hormones on bovine oocyte maturation and fertilization in vitro (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 189-201 
    Details
    ISSN: 0148-7280
    Keywords: cow ; embryo ; fetal calf serum ; luteinizing hormone ; insemination ; cumulus cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three approaches were investigated for improvement of in vitro maturation (IVM), in vitro fertilization (IVF), and early embryonic development in cattle. These were: 1) Selection of oocytes, 2) medium supplementation with fetal calf serum (FCS) and cow sera (DO, Dl, D10, and D20 to correspond with estrus, metestrus, diestrus, and proestrus, respectively), and 3) addition of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol-17β (E2)during maturation. Greater proportions (percentage) of oocytes initially selected for their compact cumulus cells completed IVM and IVF when compared to unselected oocytes (P 〈 .05). Proportions (percentage) of selected oocytes that matured and cleaved after in vitro insemination according to serum type used for IVM were: FCS: 110/175 (62.9%) and 37/110 (33.6%) and DO: 130/145 (89.7%) and 52/130 (40.0%); D1 127/130 (97.7%) and 41/127 (32.3%); D10 95/98 (96.9%) and 35/95 (36.8%); D20:113/116 (97.4%) and 49/113 (43.4%). A higher proportion (P 〈 .05) of embryos resulting from the D20 group reached four- and eight-cell stages. In FCS-supplemented maturation media with no hormones added during maturation (control), results of IVM and IVF were 157/265 (59.2%) and 39/157 (24.8%), respectively. With E2 (1 μg/ml) and FSH (5 μg/ml), comparable results were 189/215 (87.9%) and 71/189 (37.6%); with E2 (1 μg/ml) plus LH (10 μml), 280/327 (85.6%) and 111/280 (39.6%). Added hormones improved IVM results (P 〈 .05) and, when FSH or LH was added with E2, in vitro development to four- and eight-cell stages was markedly enhanced (P 〈 .05). Selection of oocytes, D20 serum, and added E2 and FSH or LH for IVM improved in vitro development of bovine embryos after IVF.
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    Gamete processing in an environmental chamber: Effect on in vitro fertilization outcome (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 229-232 
    Details
    ISSN: 0148-7280
    Keywords: mouse model ; IVF ; environment ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A study of mouse gamete processing for in vitro fertilization (IVF) under various conditions showed that it is necessary to control the atmosphere if the temperature is raised from 22°C to 37°C. The data suggest that maximum IVF success is attained by processing the gametes at 37°C, under an atmosphere of 5% O2 and 5% CO2, and overlaying the medium with silicone oil.
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    Incorporation and fate of specific sperm plasma membrane components following insemination as revealed by ultrastructural immunocytochemistry (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 215-228 
    Details
    ISSN: 0148-7280
    Keywords: Membrane fusion ; membrane fluidity ; protein diffusion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Studies have been carried out to 1) further characterize sperm specific plasma membrane polypeptides (33 and 35 kDa) that are recognized by a monoclonal antibody previously described (Longo, 1989) and 2) follow the incorporation and dispersal of these proteins within plasmalemmae of monospermic and polyspermic sea urchin (Arbacia punctuluta) eggs and oocytes utilizing immunocytochemical methods at the ultrastructural level of observation. Only sperm labeled when incubated with monoclonal antibody to the 33 and 35 kDa proteins followed by colloidal gold-tagged second antibody. Colloidal gold label was observed on the egg plasma membrane immediately after gamete membrane fusion; the amount and extent of label, i.e., the distance from the site of sperm incorporation, increased with time postinsemination. By 20 min postinsemination approximately one hemisphere of the inseminated egg/oocyte was associated with label. The expanding distribution of colloidal gold label on inseminated eggs and oocytes vs. time reflects the free diffusion of 33 and 35 kDa sperm surface proteins among egg/oocyte plasma membrane components. Label was also found in forming endocytotic vesicles, suggesting that sperm plasma membrane proteins may be internalized.
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    Analysis of the first cell cycle in the cross between hamster eggs and human sperm (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 299-308 
    Details
    ISSN: 0148-7280
    Keywords: human sperm chromatin ; S-phase ; DNA synthesis ; bromodeoxyuridine ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Golden hamster eggs fused with human sperm were pulsed with bromodeoxyuridine to determine the timing of S-phase and the length of the first ceil cycie in this hybrid cross. Fused eggs were fixed and pronuclei scored for incorporation of the thymidine analogue detected by indirect immunofiuorescence. Although S-phase started synchronously 3-3.5 hr after coincuba-tion of sperm and eggs, its duration was variable such that two-cell stages appeared at 16 hr while a proportion of pronuclei was still engaged in DNA synthesis. Unlike rodent sperm chromatin, human sperrn chromatin was able to participate in DNA synthesis well before its maturation into a fully developed pronucleus. Human sperm chromatin appears able to function under conditions different in several respects from those in human eggs.
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    URL: http://dx.doi.org/10.1002/mrd.1120230307
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    Effect of the degree of maturation of mouse oocytes at fertilization: A source of chromosome imbalance (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 205-218 
    Details
    ISSN: 0148-7280
    Keywords: oocyte aging ; immature oocytes ; oocyte maturation ; chromosome abnormalities ; in vitro fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: It has been suggested that the abnormal maturation of the human oocyte during fertilization in vitro may result in chromosome imbalance and, induce embryonic loss. Using a mouse model, we have studied the influence of the degree of oocyte maturation (either immaturity or overmaturity) on the chromosome characteristics of embryos at the first-cleavage division. Immature oocytes were obtained 2-3 h or 3-4 h before the expected ovulation time (b.o.). Overmaturation was induced by aging the newly ovulated oocytes in vitro for 3,6, and 12 h. Our results show a significant decrease in the fertilization rate in the immature groups (65.53% at 2-3 h b.o. and 16.59% at 3-4 h b.o. vs. 78.22% at control) and after 12 h of in vitro aging (69.39%), while a significant increase of this parameter was found at 3 h of aging (82.59%) as compared to the other groups. No significant differences were found in the occurrence of aneup'.oidy or hypcrhaploidy in embryos obtained from immature, newly ovulated, and overmature oocytes. Finally, an increased incidence of polyploidy was detected in immature, 2-3 h b.o. (31.20%), and overmature, 3 h (23.04%) and 6 h (31.61%), groups as compared to the control group (14.59%).
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    URL: http://dx.doi.org/10.1002/mrd.1120240208
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220201
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    Kinetics of spontaneous and induced acrosomal loss in human sperm incubated under capacitating and noncapacitating conditions (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 109-122 
    Details
    ISSN: 0148-7280
    Keywords: acrosome reaction ; capacitation ; ionophore ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The kinetics of spontaneous and induced acrosomal loss have been studied in human sperm incubated in capacitating and noncapacitating media. Acrosomal status was quantitated using indirect immunofluorescence with a monoclonal antibody. The response of sperm to induction by calcium ionophores was time dependent reaching a maximum after 6 hours of incubation under capacitating conditions. The inducible population slowly decreased in size through the balance of a 24-hour incubation. The time-dependent development of ionophore responsiveness by sperm exposed to capacitating conditions corroborates the idea that only capacitated cells can respond to undergo acrosomal loss in response to ionophore. In contrast, only a small, constant percentage of sperm incubated under noncapacitating conditions responded to ionophore. Substitution experiments involving the addition or deletion of human serum albumin suggest that albumin is not absolutely required for capacitation but is essential for the maintenance of motility. Polyvinyl alcohol can be substituted for serum albumin, but it does not support capacitation or motility as well as HSA. These studies may provide a basis for optimizing capacitating conditions for human sperm in vitro as well as for diagnosing fertility or fertility potential based on measurements of spontaneous and ionophore induced acrosomal loss under defined culture conditions.
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    URL: http://dx.doi.org/10.1002/mrd.1120220111
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    In vitro capacitation and fertilizing ability of ejaculated rabbit sperm treated with lysophosphatidylcholine (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 131-141 
    Details
    ISSN: 0148-7280
    Keywords: acrosome reaction ; lysolecithin ; in vitro fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Four 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 tended to be superior.
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    Preimplantation mammalian aggregation and injection chimeras (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 233-247 
    Details
    ISSN: 0148-7280
    Keywords: chimera ; transgenics ; embryos ; ES cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The 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.
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    Capacitation of bovine spermatozoa by lysophospholipids and trypsin (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 193-204 
    Details
    ISSN: 0148-7280
    Keywords: in vitro fertilization ; zona pellucida ; oocyte penetration assay ; bull semen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bovine 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 trypsin.
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    Human antral follicles: Oocyte nucleus and the karyosphere formation (electron microscopic and autoradiographic data) (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 219-231 
    Details
    ISSN: 0148-7280
    Keywords: human oocyte nucleus ; karyosphere ; RNA synthesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The 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 discussed.
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    Crater defect in human spermatozoa (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 249-255 
    Details
    ISSN: 0148-7280
    Keywords: human spermatozoa ; “crater defect,” ; nuclear malformation ; acrosome malformation ; cytoskeleton ; sperm head morphogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This report describes the “crater defect” in human spermatozoa, a malformation that consists of a nuclear and acrosomal invagination present in 100% of the cells, whereas tail structure and motility are fairly normal. The defect occurs during spermiogenesis. A possible concomitance with abnormalities in the microtubular apparatus involved in the sperm molding is discussed.
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    Age dependence of bovine oocyte activation (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 265-275 
    Details
    ISSN: 0148-7280
    Keywords: bovine ; oocyte activation ; A23187 ; electric shock ; time dependent ; nuclear transfer ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The ability of bovine oocytes to undergo parthenogenetic activation using either a Ca++-Mg++-H+ ionophore (A23187) or electric shock was investigated, as a prelude to understanding activation potential following nuclear transfer into ooplasm. Oocytes were collected from slaughterhouse ovaries by aspiration of 1-5-mm follicles. The time of placement into maturation medium was noted, and maturational age (time in culture) measured from that point. After exposure to activating conditions eggs were cultured for a further 12-16 hours, fixed, and stained with aceto-orcein. Oocytes that progressed to telophase or pronuclear formation were considered activated. Concentrations of A23187 ranging from 100 pM to 100 μM showed that 1-100 μM levels resulted in 94-100% activation at 30 hours maturation. Frequency of activation differed from controls (no ionophore) at 100 nM (49%; P 〈 0.05). With A23187 maximum response occurred between 26 and 30 hours of maturation (77% and 92%, respectively). A short pulse electric shock, capable of causing oocyte membrane fusion, gave similar results relative to maturational age (82% and 90% activation for 26 and 30 hours, respectively). Therefore, maximum response to the two activating stimuli occurred in oocytes at similar maturational ages. Exposure to activating conditions prior to onset of activating ability (18 hours) followed by another exposure at 26 hours showed that the oocytes were still fully able to activate upon reaching maturational activation competence. Because cytochalasin B is present in the medium used for nuclear transfer, oocytes were incubated with cytochalasin B prior to exposure to an activating stimulus. Frequency of activation was similar to the control treatment (61% and 73%). The effect of mechanical stress of cytoplasm removal and replacement by electrofusion on activation was also not significant. Overall, maturational age of the oocyte was the main determinant of activation ability.
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    Effects of ultrasound on ovulation in the mouse (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 333-338 
    Details
    ISSN: 0148-7280
    Keywords: ultrasound ; ovulation ; hyperthermia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vitro fertilization and embryo transfer (IVF-ET) programs use ultrasound extensively for monitoring the growth of ovarian follicles and, subsequently, for confirming the presence of a fetal sac. There have been few reports of the effects of ultrasound on ovulation rates in mammals, and we report here that following exposure to continuous wave ultrasound at a spatial average intensity of 3.0 W/cm2 for five minutes, ovulation rates measured 10 days later were significantly reduced in mice. When temperature elevation of the exposed ovary was measured with a thermocouple, hyperthermia correlated with reduction in ovulation.
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    URL: http://dx.doi.org/10.1002/mrd.1120220310
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220401
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    Induction and inhibition of amphibian (Rana pipiens) oocyte maturation by protease inhibitor (TPCK) (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 339-354 
    Details
    ISSN: 0148-7280
    Keywords: meiosis ; follicle ; protease ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report for the first time that oocyte nuclear and cytoplasmic maturation are triggered in vitro in non-hormone-treated amphibian (Rana pipiens) ovarian follicles following transient exposure to synthetic chymotrypsin inhibitor Nα-tosyl-L-phenylalanine-chloromethyl ketone (TPCK). The mechanism of action of TPCK in regulating oocyte maturation was investigated and compared to that induced by progesterone or pituitary hormone. Follicular oocytes failed to mature following continuous exposure to the same doses of TPCK in the presence or absence of progesterone. Continuous treatment of follicles with lower levels of TPCK occasionally induced GVBD in the absence of progesterone and augmented maturational effects of low levels of progesterone. TPCK induced maturation of intrafollicular oocytes without stimulating progesterone production and also induced maturation of naked oocytes. Stimulation of follicular progesterone synthesis following gonadotropin stimulation or addition of pregnenolone was inhibited by TPCK, indicating that TPCK affects metabolic processes in both the somatic and germinal components of the ovarian follicle. Oocyte maturation induced by either TPCK or progesterone was inhibited by cycloheximide, calcium-deficient medium, and forskolin. Results suggest that TPCK induces oocyte maturation independent of steroidogenesis via mechanisms similar to those triggered by progesterone involving protein synthesis, formation of cytoplasmic maturation-promoting factor (MPF), and changes in cAMP levels. Our data indicate that a chymotrypsin-like protease plays a role(s) in regulating the oocyte meiotic maturation process.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120220311
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    Cytochemical study of intracellular calcium in hamster spermatozoa during the acrosome reaction (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 375-384 
    Details
    ISSN: 0148-7280
    Keywords: sodium-calcium antiporter ; postacrosomal lamina ; membrane fusion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Calcium was localized by a pyroantimonate technique in hamster spermatozoa during the acrosome reaction and pyroantimonate precipitates were observed in the anterior region of the acrosome. The calcium was also localized in the postacrosomal lamina of spermatozoa undergoing the acrosome reaction. Spermatozoa, incubated in capacitating medium containing verapamil, showed denser precipitates with an increase in concentration of this drug. Ionophore A23187 enhanced binding of calcium to the acrosomal region. The sodium channel inhibitor amiloride inhibited the acrosome reaction and the pyroantimonate precipitates were absent in these spermatozoa, whereas ionophore monensin enhanced the acrosome reaction. This suggests that the Na+/Ca++ antiporter may be responsible for intracellular Ca++ regulation during the acrosome reaction in hamster spermatozoa.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120220404
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    Differentiation of binuclear spermatozoa in mice (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 399-410 
    Details
    ISSN: 0148-7280
    Keywords: gametogenesis ; mice ; Golgi apparatus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In an electron microscopy study of abnormal spermatogenesis in mice, we have found that two discrete haploid nuclei may be located in a single spermatid cytoplasm after the second meiotic division. The spermatid continues to differentiate and forms a binucleate spermatozoon with both nuclei separately packaged within the sperm head. The Golgi apparatus of the double spermatid forms a single proacrosome that attaches to both nuclei. Apparently, one acrosomal structure differentiates to cover and compartmentalize the two haploid nuclei within the sperm head. Chromatin condensation appears normal. The head morphology and number of flagella vary in mature spermatozoa produced by this process. This work demonstrates one pathway by which polyploid spermatids continue to differentiate to spermatozoa after failure of cytoplasmic division or possibly cellular fusion.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120220406
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    Distribution and role of microfilaments during early events of sheep fertilization (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 411-425 
    Details
    ISSN: 0148-7280
    Keywords: actin ; egg ; cytochalasin D ; NBD-phallacidin ; anti-actin antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The distribution of actin was studied during early events of sheep fertilization by fluorescence microscopy after staining with 7-nitrobenz-2-oxal-1.3 diazole (NBD)-phallacidin and anti-actin antibody and by electron microscopy after heavy meromyosin labelling. Unfertilized and fertilized eggs exhibited a continuous band of fluorescence with both NBD-phallacidin and anti-actin antibody. Unlike in mice, no high concentration of actin overlying the spindle was detected in ovulated sheep oocytes. At the site of sperm head incorporation, the fertilization cone developed above the decondensing male chromatin and was underlined by a submembranous area rich in microfilaments. A similar actin network was observed in the cortex of the second polar body.Cytochalasin D was used to investigate the role of actin during the fertilization process. This drug did not prevent sperm fusion and incorporation but inhibited polar body abstriction and fertilization cone development and retarded sperm tail incorporation. Moreover, in the presence of the drug, the anchorage of the metaphase II spindle at the surface of the egg was destroyed. The role of microfilaments in these early events is discussed.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120220407
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    Masthead (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230101
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    Effects of non-24-hour days on reproductive efficacy and embryonic development in mice (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 435-441 
    Details
    ISSN: 0148-7280
    Keywords: low mating rate ; low embryonic weight ; retarded development ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: ICR female mice were exposed to either 22 (L11, D11) or 26 hour day (L13, D13) light/dark cycles for at least 2 weeks before mating and/or during pregnancy. The mating rates of these animals decreased considerably. When pregnant females were examined at gestation days 12.0 or 17.5, resorption rates were increased, the embryos weighed less, and development was retarded in the experimental groups with preconceptional exposure to non-24-hour days. We speculate that in mice maternal and paternal pre- and periconceptional environment of daily light/dark cycles is important for normal reproductive efficacy and normal embryonic development during pregnancy.
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    Microsurgical bisection of porcine morulae and blastocysts to produce monozygotic twin pregnancy (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 1-9 
    Details
    ISSN: 0148-7280
    Keywords: micromanipulation ; embryo bisection ; transfer ; porcine monozygotic twin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Porcine morulae were bisected by a glass needle after softening of zonae pcllucidae by pronase followed by a treatment with 0.05% trypsin/0,02% EDTA for decreasing intercel lular junction of blastomeres. Transfer of 49 half-morulae to three recipients resulted in one pregnancy. The blastocysts were bisected symmetrically so as to leave a cellular bridge between the sister half-embryos after the softening of zonae followed by or without the trypsin/EDTA treatment. Transfer of 47 monozygotic (MZ) pairs of half-blastocysts to nine recipients resulted in four pregnancies. A litter of nine fetuses was obtained from seven MZ pairs of half-blastocysts, demonstrating that at least two pairs of MZ twin fetuses were produced. It is thought that the procedure for bisecting blastocysts developed in this study is one of the potential methods of producing porcine MZ twins.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120230102
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    Pregnant mares' serum gonadotropin source influences fertilization and fresh or thawed embryo development, but the effect is genotype specific (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 11-20 
    Details
    ISSN: 0148-7280
    Keywords: gonadotropin source ; in vitro embryo development ; embryo cryopreservation ; genotype ; mouse ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The influence of the source of pregnant mares' serum gonadotropin (PMSG) on the num ber, quality, and in vitro development of mouse embryos before and after freezing was evaluated among three genotypes: N:NIH(S), C57BL/6N, and C3H/HeN-MTV-. Immature females were given PMSG from one of five commercial sources. Following col lection ( 116 hr later), embryos were evaluated for stage of development, and four-to eight-cell embryos were pooled within genotype and assigned to standardized fresh or freeze-thaw culture trials. Different PMSG sources stimulated the production of different num bers of total embryos (P 〈 0.05) but not necessarily more embryos suitable for freezing. Differences in embryo production among genotypes indicated that absolute embryo num bers using a single mouse genotype may not accurately reflect the potency of a specific gonadotropin source. The PMSG source also affected the ability of an embryo to survive in culture either immediately after collection or after frozen storage. The effect, however, was genotype specific, with some mouse strains being relatively insensitive to PMSG source, whereas gonadotropin source played a major role in determining in vitro viability in others. Development rates for freshly collected embryos differed, often inconsistently, from those of thawed embryos regardless of the PMSG source used, demonstrating that fresh embryo development cannot be used to estimate expected post-thaw survival. In vitro development of thawed embryos is influenced not only by genotype, but also the source of the gonadotropin used to promote follicular development and oocyte maturation. These findings may explain, in part, the wide variation in embryo viability and culture rates reported among laboratories and intraspecies animal populations.
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    Heparin and glutathione: Physiological decondensing agents of human sperm nuclei (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 39-47 
    Details
    ISSN: 0148-7280
    Keywords: nuclei decondensation ; thiol reagents ; reduced glutathione ; glycosaminoglycan ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: It has been proposed that reduced glutathione (GSH) or other thiol reagents may partici pate in the basic mechanism by which sperm-decondensing activity is accomplished. How ever, in vitro, these reagents seem to be inactive and require the presence of other chemi cals, usually detergents. Heparin binds specifically to the sperm membrane and provokes the decondensation of human sperm and the activation of DNA transcription and synthe sis. However, the concentrations at which these effects occur seem to be higher than those expected under physiological conditions. In the present study, thiol reagents at 10 mM concentration, either alone or combined, were completely ineffective in inducing any sig nificant nuclear decondensation after prolonged exposures (24 hr) of incubation. Heparin, 153.8 μM, was capable of inducing only a small increase in nuclear swelling. However, GSH at concentrations as low as 0.1 mM in combination with heparin induces deconden sation of human sperm nuclei in vitro. When GSH concentration was kept constant at 5 mM, nuclear decondensation was induced with heparin at concentrations as low as 11.6 μM, and a maximal decondensation (90%) was obtained with only 21.6 μM of heparin. The latter is more than ten times less than the minimal active concentration of heparin used alone.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120230105
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    Unstable genes affecting chloroplast development in soybean (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 532-541 
    Details
    ISSN: 0192-253X
    Keywords: Variegation ; Transposable elements ; Thylakoid membranes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Y18 is a nuclear gene of soybean (Glycine max) necessary for normal chloroplast development. An unstable allele (Y18-m) of the Y18 gene has been previously characterized genetically [Peterson and Weber: Theor Appl Genet 39:156-162, 1969.] Plants homozygous for the unstable allele produce leaves that exhibit a variegated pattern of green and yellow leaf sectors, indicating somatic mutability events. Germinal instability is detected by the recovery of either pure breeding dominant green (rare) or pure breeding recessive yellow (frequent) plants from the mutable stock. In contrast to most unstable genes identified in other plant systems, the Y18-m mutation is from the dominant green state to the recessive yellow state, producing a pattern of “reverse variegation.” Current work has focused on further characterization of this mutation at the whole plant level as well as at the biochemical level. These results include observations on the cell- and tissue-type specificity of the mutation, stability of the recessive yellow mutation, and a biochemical analysis of mutant and normal thylakoid membranes to identify the specific polypeptides affected by the y18 mutation. Several polypeptides of the thylakoid membranes are missing, and many, including the major light harvesting complex (LHCP) polypeptides, are reduced. Messenger RNAs for LHCPII were also reduced to a greater extent than other leaf transcripts in the yellow sectors of variegated plants. A comparison of Y18-m to other soybean mutable genes and transposable element insertions is made.
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    URL: http://dx.doi.org/10.1002/dvg.1020100612
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    DNA methylation in fungi (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 63-69 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100202
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    Set of proteins shows abnormal posttranslational modification in embryos homozygous for dominant T-mutations (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 53-62 
    Details
    ISSN: 0192-253X
    Keywords: Mouse T-locus ; Two-dimensional gel electrophoresis ; Embryonic development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: T and Tc are dominant mutations in the mouse that affect neuroaxial development when heterozygous and cause embryonic death when homozygous. Embryos were analyzed individually by two-dimensional gel electrophoresis at 9½ days gestation, 1 day before homozygotes die in utero. A comparison of the protein patterns of mutant homozygotes with those of their littermates revealed a set of proteins (T-proteins) that showed isoelectric point (pl) polymorphism. All the T-proteins were more basic in mutant homozygotes. These polymorphisms could be detected, although they were less pronounced, in embryos as young as 7½-day presomite stages, when it is impossible to distinguish homozygous mutants grossly. Interestingly, the same proteins show a pl shift from basic to acidic in wild-type embryos during development from 7½ to 9½ days. Thus, it appears that in T and Tc mutants a developmentally specific posttranslational acidic modification of these proteins is disturbed. The likely cause of the abnormality is a defect in some mechanism for phosphorylation, since the T-proteins of wild-type embryos were shifted to higher pls by phosphatase treatment. This disturbance appears to be localized to axial structures (neural tube, somites, and surrounding mesenchyme) since only these structures, and not the rest of the mutant homozygous embryos, contain abnormally basic T-proteins.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100108
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    Genetic analysis of modifiers affecting sexual dimorphism and temperature sensitivity of bx1 in Drosophila melanogaster (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 106-111 
    Details
    ISSN: 0192-253X
    Keywords: Bithorax complex ; Variable penetrance suppression ; Enhancement ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Two modifiers of bithorax1 phenotypic expression are described. An X-chromosome region is associated with sexual dimorphism in bx1 penetrance. It is hypothesized that sexual dimorphism is in part due to a lack of dosage compensation of the modifier, in males. A third chromosome region that segregates with the pink peach allele is implicated in mediating temperature sensitivity. By appropriate combinations of modifiers, both sexual dimorphism and temperature sensitivity can be greatly reduced.
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    Masthead (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100301
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    Introduction (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 123-123 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100302
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    Analysis of Adh gene regulation in Drosophila: Studies using somatic transformation (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 210-219 
    Details
    ISSN: 0192-253X
    Keywords: Intron ; Alcohol dehydrogenase ; Enhancer ; Promoter ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used in vitro mutagenesis and somatic transformation [Sofer and Martin, 1987a; Martin et al., 1986] to investigate the role of cis-acting sequences in the control of alcohol dehydrogenase gene expression in larvae of Drosophila melanogaster. Two sets of experiments were carried out. In the first, a series of aeletions were constructed in the region upstream of the proximal transcriptional start site. In the second, one or both introns were removed from within the structural gene. These constructs (on circular plasmids) were injected into Adh-null embryos and ADH activity was assayed in third instar larvae of the injected generation. The first set of experiments indicated that there are at least three distinct regulatory regions essential for larval activity located in the 5′ flanking region of the gene. One, in an area that includes the TATA box, was found to be necessary but not sufficient for larval ADH activity. Two others, further upstream, seemed to have enhancer-like properties because their absence could be compensated by a second copy of the Adh gene on the same plasmid molecule. The second set of experiments showed that neither the tis-sue distribution nor amount of ADH activity was affected by the removal of one or both introns from the Adh gene.
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    Larval fat body-specific gene expression in D. melanogaster (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 220-231 
    Details
    ISSN: 0192-253X
    Keywords: Drosophila ; Fat body ; Ecdysone ; cis-acting regulatory elements ; Development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The P1 gene, together with the LSP-1a, -1β, and -ly, LSP-2, and P6 genes, is expressed exclusively in the larval fat body of D. melanogaster during the third instar. In vivo mapping of the cis-acting regulatory sequences of the P1 gene was carried out using hybrid constructs with three different reporter genes and a combination of transient and germline transformation assays. This revealed that regulatory elements involved in the setting up of the temporal and spatial specificities of transcription of the P1 gene are located in a short DNA region immediately upstream of the mRNA transcription start. This region includes on element that behaves as a fat-body transcriptional enhancer and element(s) required for ecdysone inducibility of transcription of the P1 gene.
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    Molecular genetics of dopa decarboxylase and biogenic amines in Drosophila (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 232-238 
    Details
    ISSN: 0192-253X
    Keywords: Transcriptional regulation ; Alternate splicing ; Neurotransmitters ; Learning ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The gene Ddc encodes two isoforms of the enzyme dopa decarboxylase in Drosophila. These gene products catalyze the final steps in the synthesis of the biogenic amines sero-tonin and dopamine. This article summarizes recent progress in understanding the tissue- and cell-specific regulation of Ddc, which occurs at both the transcription and alternate splicing levels. In addition, results that are pertinent to understanding the roles of biogenic amines in the neurophysiology of Drosophila are discussed.
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    URL: http://dx.doi.org/10.1002/dvg.1020100312
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    The gypsy retrotransposon of Drosophila melanogaster: Mechanisms of mutagenesis and interaction with the suppressor of Hairy-wing locus (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 239-248 
    Details
    ISSN: 0192-253X
    Keywords: Transposable element ; Transcription factor ; Suppression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used the yellow gene of Drosophila melanogaster as a model system in which to study the molecular mechanisms by which the gypsy retrotransposon causes mutant phenotypes that can be reversed by nonalleiic mutations at the suppressor of Hairy-wing locus. This gene encodes a 109,000 dalton protein that contains an acidic domain and 12 copies of the Zn finger motif, which are characteristic of some transcription factors and DNA binding proteins. The suppressible y2 allele is caused by the insertion of the gypsy element at -700 bp from the start of transcription of the Yellow gene, resulting in a phenotype characterized by mouth parts and denticle belts in the larvae, and by bristles in the adults, that show wildtype coloration, but mutant wings and body cuticle in the adult flies. This phenotype is the result of the interaction of gypsy sequences homologous to mammalian enhancers with tissue-specific yellow transcriptional regulatory elements located upstream from the gypsy insertion site and responsible for the expression of the yellow gene in the mutated tissues. This interaction is dependent on the binding of the su(Hw) protein to the specific gypsy sequences involved in the induction of the mutant phenotype.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100313
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    Genetic interactions of the Suppressor 2 of zeste region genes (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 249-260 
    Details
    ISSN: 0192-253X
    Keywords: Regulatory genes ; Pc group ; Drosophila embryogenesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A wide variety of gain of function mutations have been induced in the Posterior Sex Comb (Psc) - Aristapedioid (Arp) - Suppressor 2 of zests(Su(z)2) region of the second chromosome of Drosophila. This region contains at least three apparently related genes, two of which we have been studying. Psc1 has previously been used to identify Psc as a Pc group gene; however, it is a complex mutation with both gain and loss of function character. We report here that the Pc group character of Psc is not due to a gain of function and presumably reflects the function of the wild-type gene. We also provide evidence for a maternal function for Psc, as well as the neighboring Su(z)2 gene.Su(z)2 does not appear to be a Pc group gene as it does not act in a synergistic fashion with other PC group genes in promoting posteriorly directed transformations. However, we have found that mutations in Su(z)2 do interact in a variety of interesting ways with mutations in Pc group genes.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100314
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    Hemin increases production of β-like globin RNA transcripts in human erythroleukemia K-562 cells (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 311-317 
    Details
    ISSN: 0192-253X
    Keywords: β-globin ; Human erythroleukemia cells ; RNA transcripts ; K562 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previous studies have indicated that control and hemin-treated human eryth-roleukemia K-562 cells fail to produce adult-type β-globin mRNA transcripts and to translate them into nascent β-globin chains. Expression of the β-globin DNA sequences in K-562 cells can occur, however, under certain conditions. To readdress this issue and to examine the possibility of whether these cells produce immature and untranslatable β-globin RNA transcripts, we prepared total cyto-plasmic RNA from control and inducer-treated cells and performed Northern blot hybridization analysis using 5′ end-labeled fragments of the human β-globin DNA rather than 3′ end fragments as probes. Although hybridization of both cytoplasmic and nuclear K-562 RNA with a32P-labeled 3′ end fragment (1.6kb Bam H1 cut) coding for a large part of the first exon of β-globin failed to detect β-globin RNA transcripts, hybridization with a 5′ end 32P-labeled 2.0kb Bam H1 fragment (coding for the third exon and part of the second) revealed the presence of relatively small (〈7S) RNA molecules both in nuclear and cytoplasmic fraction. S1 nuclease mapping of both cytoplasmic and nuclear RNA with the use of 5′ end-labeled 2.0 kb Bam H1 fragment of human β-globin DNA indicated protection of a small portion located 64bp 5′ upstream from the Bam H1 site of the second exon. The amount of protected portion was relatively higher in K-562 cells undergoing erythroid maturation. These findings suggest that control and differentiating K-562 cells synthesize β-globin-like RNA transcripts that are 3′ end short, immature, and unable to give rise to adult β-globin chains. These results also indicate that K-562 cells may lack factors that are unique for transcription and processing of the human β-globin RNA transcripts.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100406
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    Erratum (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 345-345 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100411
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    Masthead (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100501
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    Announcement (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 347-347 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100412
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    Regulation of catalase-specific mRNA and its processing during development in mice (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 339-344 
    Details
    ISSN: 0192-253X
    Keywords: Delayed processing ; Splicing ; Transcription ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study deals with the pattern of developmental expression of the catalase gene in mice. We have used a mouse catalase 2 kb cDNA (pMCT-1) and its 1.4 kb 5′ fragment as probes to characterize the transcripts during embryonic development and differentiation. Total RNA was isolated from 8 days postconceptus (p.c.) whole embryos and from livers and carcasses of 13, 15, and 18 day p.c. embryos as well as from the livers of newborn and adult mice of the S.W. strain. The RNA was applied on slot blots, and run on agarose gels to generate northern blots. Blots were hybridized with the 32P-labeled cDNA probe under different stringency conditions. Autoradiograms were scanned with a densitometer to quantify relative hybridization signals of RNA samples obtained from two or three individual mice representing each stage of development.The catalase transcript is detectable as early as 8 days p.c. with the beginning of somite formation. At this stage, it is primarily in the form of a 12.2 kb transcript. One additional band (2.4 kb) is also apparent at this stage although at a very low intensity. The intensity of the two bands increases with development, particularly during 13-18 days p.c. in liver and carcass. The 2.4 kb RNA band increases sharply from day 8 through 13, 15, and 18 days p.c. and is confined primarily to the liver. Interestingly, only the 2.4 kb RNA band is seen at and after birth. The 2.4 kb RNA is the known mature message of the catalase gene in mice. The presence of large catalase-specific RNA species (seen during development in utero only) is interpreted as the primary transcript of this gene. The complete and efficient processing of this primary transcript takes place only after birth and primarily in the liver, which may be related to the physiological role of this enzyme in oxygen metabolism, particularly stressful superoxides, expected with independent respiration. At a lower stringency wash of the northern blots, a 9.5 kb RNA was seen during a narrow window of in utero development. This 9.5 kb band may represent an uncharacterized catalase-related gene with a possible role in development and differentiation.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100410
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    Expression of a methotrexate resistant dihydrofolate reductase gene in transgenic mice (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 349-355 
    Details
    ISSN: 0192-253X
    Keywords: SV40 promoter ; Expression vector ; Drug resistance ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have previously demonstrated systemic resistance to methotrexate (MTX) in transgenic mice carrying a foreign, mutant dihydrofolate reductase (DHFR, E.C. 1.5.1.3) gene. The new gene was introduced as a cDNA cloned into an expression vector driven by the simian virus 40 (SV40) early promoter. Previous physiologic studies suggested that transgenic mice tolerated drug doses invariably lethal to controls on the basis of gastrointestinal (GI) resistance to MTX. In the present study we evaluated foreign gene expression at the RNA level in the three major sites of MTX toxicity: intestine, liver, and bone marrow.The transgene was transcriptionally active in small bowel, and levels of expression were high in animals tolerating the largest doses of MTX. The gene was also expressed in the liver in some pedigrees, but was not detected in hemopoietic tissues of any of the pedigrees tested. Our studies correlate the site of expression of a drug resistant dhfr gene with an altered physiologic response to MTX, and demonstrate that transgenic mice can be used as a test system for expression of genes considered for use in somatic gene therapy.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100502
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    Hyperinsulinemia in transgenic mice carrying multiple copies of the human insulin gene (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 356-364 
    Details
    ISSN: 0192-253X
    Keywords: Glucose intolerance ; Insulin resistance ; Diabetes mellitus ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We are investigating human insulin gene expression in transgenic mice. An 8.8 kilobase (kb) human genomic DNA fragment, including the insulin gene (1.4 kb) and 2 kb of 5′ human flanking sequences, was introduced into mouse embryos by pronuclear microinjection. Two lines of transgenic mice have been established, both of which carry the intact human gene in multiple copies. Animals from both lines have significantly higher insulin levels than control mice, and the degree of hyperinsulinemia shows a positive correlation with human gene copy number in the two lines. Expression of the human gene is confirmed by the detection of human C-peptide in plasma. Tissue specificity of expression is maintained, with human insulin mRNA detectable only in the pancreas. The transgenics maintain normal fasting blood glucose in spite of their high insulin levels, but preliminary studies show them to be glucose intolerant when given a glucose load. These mice provide a model system for further studies on the regulation of insulin gene expression and on the effects of chronic hyperinsulinemia on glucose homeostasis.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100503
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    Liver-specific and high-level expression of human serum amyloid P component gene in transgenic mice (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 365-371 
    Details
    ISSN: 0192-253X
    Keywords: Pentraxins ; Acute phase protein ; Lipopolysaccharide ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: To analyze the regulation of human serum amyloid P component (SAP) gene expression, we have produced seven transgenic mice. The 3.3 kb human SAP genes containing about 0.8 kb of 5′ and 1.5 kb of 3′ flanking region were injected into fertilized eggs of C57BL/6 mice. In five of the seven transgenic mice, human SAP was detected in the sera and serum concentrations were higher than that of human serum in three lines. The human SAP gene was expressed only in the liver. Amounts of human mRNA in the liver and serum concentrations of human SAP were roughly proportional to the copy number of the integrated gene. Human SAP production lowered the serum levels of mouse endogenous SAP. With the intraperitoneal administration of lipopolysaccharide, the mRNA levels in the liver and serum levels of mouse SAP increased several-fold in both the control and transgenic mice. On the other hand, neither the mRNA nor the serum levels of human SAP increased significantly.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100504
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    Developmental effects of modifiers of the vg mutant in Drosophila melanogaster (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 386-392 
    Details
    ISSN: 0192-253X
    Keywords: Vestigial ; Cell death ; Modifier genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An analysis of the modifiers affecting the expression of the vg gene was performed. We selected for weak and strong expression of the vg mutant in 2 segregating populations obtained by crossing a vestigial stock with an Oregon laboratory stock (O) and with a wild strain (B) captured near Bologna, Italy. The selection for enlarged wings was more effective in the vg B population where wild wings appeared from the lCth generation. The assay of the three major chromosomes showed that the modifiers are located on chromosomes 2 and 3. The mutant imaginal disc cell death phenotype is evident in vg/vg strains that have a wild-type wing phenotype. It is suggested that the selected modifiers do not prevent cell death but induce regenerative growth.
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    URL: http://dx.doi.org/10.1002/dvg.1020100506
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    Temporal and tissue-specific expression of myosin heavy chain isoforms in developing and adult avian muscle (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 372-385 
    Details
    ISSN: 0192-253X
    Keywords: Monoclonal antibodies ; Myogenesis ; Adult isoforms ; Quail ; Chicken ; Muscle development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have raised monoclonal antibodies (Mabs) to myosin heavy chain isoforms (MHCs) that have specific patterns of temporal expression during the development of quail pectoral muscle and that are expressed in very restricted, tissue-specific patterns in adult birds. We find that an early embryonic, a perinatal, and an adult-specific, fast myosin heavy chain a.e co-expressed at different levels in the pectoral muscle of 8-12 day quail embryos. The early embryonic MHC disappears from the pectoral muscle at approximately 14 days in ovo, whereas the perinatal MHC persists until 26 days post-hatching. The adult-specific MHC accumulates preferentially and eventually completely replaces the other isoforms. These Mabs cross-react with the homologous isoforms of the chick and detect a similar pattern of MHC expression in the pectoral muscle of developing chicks. Although the early embryonic and perinatal MHC isoforms recognized by our Mabs are expressed in the pectoral muscle only during distinct developmental stages, our Mabs also recognize MHC isoforms present in the heart and extraocular muscle of adult quail. Immunofingerprinting using Staphylococcus aureus protease V8 suggests that the early embryonic and perinatal MHC isoforms that we see are strongly homologous with the adult ventricular and extraocular muscle isoforms, respectively. These observations suggest that at least three distinct MHC isoforms, which are normally expressed in adult muscles, are co-expressed during the early development of the pectoral muscle in birds. In this respect, the pattern of expression of the MHCs recognized by our Mabs in developing, fast muscle is very similar to the patterns described for other muscle contractile proteins.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100505
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    Masthead (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020100601
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    Characterization of bz1 mutants isolated from mutator stocks with high and low numbers of Mu1 elements (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 460-472 
    Details
    ISSN: 0192-253X
    Keywords: Transposable elements ; Maize ; Mutation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The high frequency of mutations in Mutator stocks of maize is the result of transposition of Mu elements. Nine different Mu elements that share the 220 bp Mu terminal inverted repeats have been described. Mul elements have been found inserted into most of the molecularly characterized mutant alleles isolated from Mutator stocks, and most Mutator stocks contain a high number of Mul elements (10-60). However, it is clear that additional Mu elements, which share the Mul termini but have unrelated internal sequences, can also transpose in Mutator stocks. We were interested in comparing the mutation frequency and type of elements that inserted into a particular locus when Mutator stocks with differing numbers of Mul elements were utilized. Furthermore, previous studies with Mu-induced mutations have demonstrated that the element that inserted most frequently was Mul. Therefore, to try to obtain Mu elements different from Mul we utilized a stock that had a low number (3-6) of Mul elements as well as a Mutator stock with a more typical number of Mul elements (20-60).Utilizing both stocks, we isolated numerous mutants at one gene, Bronze1 (Bz1), and compared the type of elements inserted. In this paper we report that both the high and low Mu1 stocks produced bz1 mutants at frequencies characteristic of Mutator stocks, 6.6 and 4.3 ± 10-5, respectively. We describe the isolation of 20 bz1 mutations, and the initial molecular characterization of eight unstable mutations: two from the high Mu1 stock and six from the low Mu1 stock. The six alleles isolated from the low Mu1 stock appear to contain deleted Mu1 elements, and the two alleles isolated from the high Mu1 stock contain elements very similar to Mu1. When the mutants from the low Mu1 stocks were examined, it was found that the Mu1 -related elements increased from 3-6 copies to 9-20 copies in one generation. The high number of Mu1 -related elements was maintained in subsequent out-crosses. This spontaneous activation and amplification of Mu -related elements occurred in at least 1% of the low Mu1 plants.
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    URL: http://dx.doi.org/10.1002/dvg.1020100607
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    Genetic analyses of putative two-element systems regulating somatic mutability in Mutator-induced aleurone mutants of maize (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 10 (1989), S. 482-506 
    Details
    ISSN: 0192-253X
    Keywords: Mutator ; Transposable elements ; Controlling elements ; Autonomous elements ; Regulator elements ; Mutable genes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Mutator transposable element system (Mu) of maize has been responsible for the induction of numerous mutable aleurone mutants of maize. Unlike similar mutants induced by other transposable element systems, the mutability of Mu-induced mutants did not seem initially to be regulated by an independent autonomous or regulator element. However, in a continuing study of two Mu-induced a1 mutable mutants (a1-Mum2) and a1-Mum3, lines have been obtained that give evidence of an independently segregating regulator of somatic mutability. Data from several generations of crossing are presented indicating that intense somatic mutability in many of these stocks is under the control of an independent regulator. However, testing of other lines, which initially gave evidence of the presence of an independent regulator, were negative. Some of these latter lines could be expected to have Mutator elements that were modified (methylated) at sites recognized by certain restriction endonucleases. Modification of Mu elements, which is known to affect the expression of somatic mutability, might, at times, be responsible for producing conditions that mimic the segregation of an independent regulator. Lines with stable derivatives of the a1-Mum2 and a1-Mum3 can recover intense somatic mutability by crossing with germinally active Mutator stocks. Thus, active Mutator lines contain regulator elements and evidence is presented suggesting that such lines have multiple copies of these elements. Most a1- Mum2 and a1-Mum3 stocks segregating for a regulator do not have germinal Mutator activity. Thus the presence of one or a few putative regulator elements does not necessarily account for the high level of germinal activity in most Mutator stocks.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020100609
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    Specific absorption rate (SAR) in models of the human head exposed to hand-held UHF portable radios (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 10 (1989), S. 173-186 
    Details
    ISSN: 0197-8462
    Keywords: dosimetry ; transceivers ; radiofrequency radiation ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Specific absorption rate (SAR) was measured in models of the human head exposed to hand-held portable radios (“transceivers”) transmitting at frequencies in the 800-MHz band. An isotropic implantable electric-field probe was used to measure internal fields induced in the head models, and SARs were determined by calculation. As well as determining representative values and distributions for SARs under various conditions, it was shown that antenna type and orientation with respect to the head are important factors affecting energy absorption.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/bem.2250100206
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