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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of capacitation in bat sperm monitored by zona-free hamster ova (1981)
    New York, NY : Wiley-Blackwell
    Gamete Research 4 (1981), S. 525-533 
    Details
    ISSN: 0148-7280
    Keywords: capacitation ; fertilization ; spermatozoa ; in vitro ; Little Brown Bat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The temperature dependence of capacitation in bat sperm (Myotis lucifugus lucifugus) was studied by monitoring fertilizations rates of zona-free hamster ova at different temperatures. Spermatozoa were cultured in BWW medium at temperatures 4°C, 24°C, 32°C, 42°C, and 55°C from 0-24 hr. Activation of sperm could be determined visually due to the change in movement seen through light microscopy. Activation was later confirmed by higher rates of fertilization. Preincubation of the bat sperm was found to have a direct effect on the success of penetration of the zona-free hamster ova. Holding bat spermatozoa at low temperature for long intervals allowed them to remain motile but unable to fertilize. Sperm are not irreversibly damaged, however, and activation, when the temperature is increased to 32°C, is faster than when sperm are intitially put at 32°C, resulting in good fertilization rates.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120040606
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  • 2
    Electronic Resource
    Electronic Resource
    Possible involvement of a sialylated component of the sperm plasma membrane in sperm-zona interaction in the mouse (1984)
    New York, NY : Wiley-Blackwell
    Gamete Research 10 (1984), S. 153-163 
    Details
    ISSN: 0148-7280
    Keywords: mouse ; sperm ; egg ; sperm plasma membrane ; in vitro ; binding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have studied the molecular mechanisms of gamete interaction in vitro in the laboratory mouse, Mus musculus. In particular, we were interested in whether this interaction is similar to a lectin-hapten-mediated process. Inhibition of sperm-zona binding was examined using various concentrations (.25 mM to 50 mM) of different sugars (sialic acid α-methylmannose, glucose, fucose, galactose, and N-acetyl-glucosamine). Sperm-zona binding was significantly decreased when eggs were pretreated with 10 mM of sialic acid or α-methylmannose but not by other sugars tested. Furthermore, treatment of capacitated sperm with neuraminidase destroyed their ability to bind and fertilize eggs. We have also used a specific lectin for sialic acid from the horseshoe crab (Limulus polyphemus) to agglutinate mouse sperm. The lectin (.120 ng/ml) mediated agglutination of mouse sperm (105 sperm/ml) was routinely observed to increase from a 10% agglutination immediately following their isolation from the epididymis to 100% agglutination 90 minutes later. Collectively, these results suggest the appearance of specific sugar moieties on the surface of the sperm plasma membrane which, in this particular species of mouse, are sialylated glycoproteins acting as ligands for specific receptors on the surface of the egg. These are the first data to indicate that sperm-egg recognition and attachment is a lectin-hapten-mediated process in the mouse.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120100207
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  • 3
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    A spectroscopic view of Epsilon Aurigae (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Spectroscopic observations from the ultraviolet, visible, and infrared obtained at the recent eclipse are discussed. The rotation curve for the disk around the secondary suggests that secondary is a low mass star (or binary). This result with the known mass function suggests that the primary may be a low mass star leaving the AGB and evolving to the white dwarf region.
    Keywords: ASTROPHYSICS
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  • 4
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    Ultraviolet spectroscopy of old novae and symbiotic stars (1981)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The IUE spectra are presented for two old novae and for two of the symbiotic variables. Prominent emission line spectra are revealed as a continuum whose appearance is effected by the system inclination. These data provide evidence for hot companions in the symbiotic stars, making plausible the binary model for these peculiar stars. Recent IUE spectra of dwarf novae provide additional support for the existence of optically thick accretion disks in active binary systems. The ultraviolet data of the eclipsing dwarf novae EX Hya and BV Cen appear flatter than for the noneclipsing systems, an effect which could be ascribed to the system inclination.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Universe at Ultraviolet Wavelengths: The First Two Yrs. of Intern. Ultraviolet Explorer; p 461-467
    Format: application/pdf
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  • 5
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    Do all barium stars have a white dwarf companion? (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: International Ultraviolet Explorer short-wavelength, low-dispersion spectra were analyzed for four barium, two mild barium, and one R-type carbon star in order to test the hypothesis that the barium and related giants are produced by mass transfer from a companion now present as a white dwarf. An earlier tentative identification of a white dwarf companion to the mild barium star Zeta Cyg is confirmed. For the other stars, no ultraviolet excess attributable to a white dwarf is seen. Limits are set on the bolometric magnitude and age of a possible white dwarf companion. Since the barium stars do not have obvious progenitors among main-sequence and subgiant stars, mass transfer must be presumed to occur when the mass-gaining star is already on the giant branch. This restriction, and the white dwarf's minimum age, which is greater than 8 x 10 to the 8th yr, determined for several stars, effectively eliminates the hypothesis that mass transfer from an asymptotic giant branch star creates a barium star. Speculations are presented on alternative methods of producing a barium star in a binary system.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 270; July 1
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  • 6
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    The ultraviolet spectrum of the twin-degenerate interacting binary G61-29 (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A low-resolution IUE spectrum (1200 A-1900 A) of the twin-degenerate white-dwarf binary star G61-29 is presented. A comparison is made to similar IUE spectra of the old novae DQ Her and V603 Aql. G61-29 shows N V 1240 A and He II 1640 A in emission. Unlike the old novae, the C IV 1550 A doublet is not present. It is proposed that the mass-losing He white dwarf (with a mass of 0.02 solar mass) is the H-exhausted, He-rich core of an old star in which the original CNO nuclei have been converted to N-14 by the CNO-cycles.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 93
    Format: text
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  • 7
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    The CN radical in diffuse interstellar clouds (1984)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A survey of 15 lines of sight for the CN B2Sigma(+) X2Sigma(+) interstellar absorption lines shows that the CN column density in diffuse interstellar clouds follows the relation log N(CN) is proportional to m log N(H2), where m is approximately equal to 3. This result is reproduced by a reaction network in which CN is produced primarily from C2 by the neutral-neutral reaction C2 + N yields CN + C, and photodissociation is the main destruction pathway for the neutral molecules CH, C2, and CN. The CN radical is the first molecular species observed in diffuse clouds that requires a neutral-neutral reaction for its formation in the gas phase. The network also reproduces the observed ratio N(CN)/N(H2).
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 219-227
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  • 8
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    Physical conditions in the accretion disk of V603 Aquilae (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Ultraviolet and optical spectra of the old nova V603 Aql are discussed. The UV-optical continuum is dominated by emission from the accretion disk. Emission lines from ions of H, He, C, N, and O are identified. These lines are probably formed in a circumstellar shell with radius comparable to the binary separation, density ten billion per cu cm, and a roughly solar chemical composition. This corona is probably heated by radiation emitted by the underlying accretion disk. Photoionization calculations of the structure and emission-line spectrum of the corona are presented, and the effects of this gas on the X-ray continuum are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 260
    Format: text
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  • 9
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    Epsilon Aurigae in eclipse. II - Optical absorption lines from the secondary (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Optical high-resolution 2.7-m McDonald Observatory observations of Epsilon Aur obtained during the 1982-1985 eclipse are discussed, with focus on the K I resonance lines, some Fe II and Ti II lines in the blue, and the near-infrared N I excitation lines. The N I lines are immune to contamination by the secondary, and their radial velocity decline over the three-year interval fits the predicted velocity curve. The 7664 A and 7699 A K I lines strengthen greatly during the eclipse due to gas in orbit around the secondary passing in front of the primary, and the velocity pattern analysis indicates a mass of the secondary to solar mass ratio of between about 3 and 6 and a primary mass of 3 solar masses. The data are consistent with the picture of a low-mass post-AGB primary having lost mass through a wind and by Roche-lobe transfer to the secondary, and which will evolve to a white dwarf in less than 10,000 years.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 98; 389-402
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  • 10
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    Lithium in lower-main-sequence stars of the Alpha Persei cluster (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Lithium abundances are presented for main-sequence stars of spectral types F, G, and K in the young open cluster Alpha Per. For 46 cluster members, a correlation between Li abundance and projected rotational velocity v sin i is found: all of the Li-poor stars are slow rotators. Two explanations are proposed to account for the correlation: (1) that the Li depletion is introduced following a rapid spin-down phase experienced by young low-mass stars, and that this episode of Li depletion may be the dominant one determining the spread of Li abundances among young low-mass main-sequence stars, and (2) that star formation has occurred over a finite period such that the older stars have undergone a spin-down and depletion of Li by a means that may or may not depend on rotation. The Li abundance in the warm and rapidly rotating stars appears to be undepleted, as is predicted by recent models of pre-main-sequence stars. The depletion observed in the cool stars exceeds the level predicted by these models.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 333; 267-276
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