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  • Cambridge University Press (CUP)  (28)
  • Biodiversitätsforschung  (28)
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  • Cambridge University Press (CUP)  (28)
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  • Biodiversitätsforschung  (28)
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  • 1
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 1993
    In:  Zygote Vol. 1, No. 1 ( 1993-02), p. 9-15
    In: Zygote, Cambridge University Press (CUP), Vol. 1, No. 1 ( 1993-02), p. 9-15
    Kurzfassung: In the marine brown alga, Fucus , two poles are differentiated before cell division determining the future rhizoid or thallus. We have used a combination of the Ca 2+ -sensitive dye Calcium Green and the pH-sensitive dye SNARF monitored at pH-insensitive wavelengths to obtain confocal ratio images of free cytoplasmic calcium distribution at different stages in polarising Fucus zygotes. These dyes have the advantage that they can be used in most confocal microscopes and their longer excitation wavelengths greatly reduce autofluorescence problems. Dyes of varying molecular weights (free acid form, 10 000 mol.wt or 70 000 mol.wt dextran-conjugated) were pressure microinjected into early zygotes which were allowed to polarise in unidirectional light. Dextran-conjugated dyes remained non-compartmentalised and fluorescence could be monitored for up to 3 days following microinjection. Currently we have been able to detect Ca 2+ gradients at the tip of the rhizoid, confirming earlier results. Localised Ca 2+ elevations have also been observed at the rhizoid pole of the polarising zygote before the onset of rhizoid germination. Limitations of this technique and the significance of these Ca 2+ gradients are discussed.
    Materialart: Online-Ressource
    ISSN: 0967-1994 , 1469-8730
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 1993
    ZDB Id: 1483381-5
    SSG: 12
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  • 2
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 1996
    In:  Zygote Vol. 4, No. 1 ( 1996-02), p. 67-72
    In: Zygote, Cambridge University Press (CUP), Vol. 4, No. 1 ( 1996-02), p. 67-72
    Kurzfassung: The experimental objective was to determine whether the capability of bovine oocyte plasma membrane to bind sperm changes during in vitro oocyte maturation and fertilisation. Binding was quantified by the intensity of tetramethylrhodamine isothiocyanate (TRITC) fluorescence at the periphery of oocytes following incubation with biotinylated sperm plasma membrane proteins and subsequent incubation with TRITC-avidin. Bovine oocytes were matured in vitro . Sample groups were removed after 0,6 and 22 h, or inseminated and further cultured for 24 or 48 h. Oocytes were denuded of cumulus cells and zona pellucida and co-incubated with 56 μg biotinylated bovine sperm plasma membrane protein for 45 min in 150 μl drops of saline-BSA. Controls were incubated for the same time period in the absence of sperm plasma membrane proteins. All oocytes were rinsed, incubated with TRITC-avidin and subsequently fixed and transferred to mounting medium. Oocytes were scanned with a confocal microscope and analysed using ImageQuant software. The binding of sperm plasma membrane was quantified by integrated fluorescent intensity in standardised ellipses spaced around the plasma membrane of the oocyte. Values are expressed as mean intensity units per 320 pixel ellipse. Binding of sperm plasma membrane continued to increase throughout in vitro oocyte maturation and fertilisation (9051, 24318 and 49953 for 0 and 22 h in vitro matured oocytes and fertilised oocytes, respectively; p = 0.0001). A dramatic decrease in sperm plasma membrane binding to the oocyte plasma membrane was observed in 2-cell embryos (mean intensity = 24477, p = 0.0001). The observed binding was primarily due to the binding of sperm plasma membrane proteins, as control oocytes incubated with TRITC- avidin only were barely visible (integrated fluorescence intensity values ranged from 8 to 3757).
    Materialart: Online-Ressource
    ISSN: 0967-1994 , 1469-8730
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 1996
    ZDB Id: 1483381-5
    SSG: 12
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  • 3
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 1949
    In:  Bulletin of Entomological Research Vol. 40, No. 3 ( 1949-12), p. 355-358
    In: Bulletin of Entomological Research, Cambridge University Press (CUP), Vol. 40, No. 3 ( 1949-12), p. 355-358
    Kurzfassung: The great increase, in recent years, in the number of contact insecticides has created a demand for methods whereby the content of active substance in samples of these insecticides may be estimated quantitatively in a simple manner. Such methods are important, because on the one hand the producer wishes to know if his product meets the necessary requirements and on the other hand the official services concerned with the control of insect pests must be able to test the fundamental value of commercial preparations. Moreover quantitative methods for the estimation of contact insecticides are useful for scientific research in this field.
    Materialart: Online-Ressource
    ISSN: 0007-4853 , 1475-2670
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 1949
    ZDB Id: 1496538-0
    SSG: 12
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  • 4
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 2006
    In:  Zygote Vol. 14, No. 3 ( 2006-08), p. 249-257
    In: Zygote, Cambridge University Press (CUP), Vol. 14, No. 3 ( 2006-08), p. 249-257
    Kurzfassung: The acrosome reaction is a fundamental event in the biology of the sperm and is a prerequisite to fertilization of the egg. Members of the Rho family of GTPases and their effectors are present in the cytoplasm and/or plasma membrane overlying the acrosome of porcine sperm. We have implicated the Rho family of GTPases and the Rho-activated kinase, ROCK-1, in mediating the zona-pellucida-induced acrosome reaction. Others have implicated the Rho GTPase in regulating the ionophore-induced acrosome reaction in the sperm of several mammalian species as well as in motility of bovine sperm. In this study, the localization of the Rho GTPases (RhoA, RhoB, Rac1 and Cdc42) as well as the effectors RhoGDI, PI(4)P5K and ROCK-1, was determined in boar, human, rat, ram, bull and elephant sperm. The four GTPases were each present in the sperm head of all species examined. RhoGDI was expressed in the head and tail of sperm from all species except pig, where it was present only in the head. PI(4)P5K was expressed in both head and tail of sperm from all species, but expression was typically weaker in the tail. Finally, ROCK-1 was expressed in the heads and tails of all sperm except that of the boar, where it was present only in the acrosomal region. These observations taken together suggest that the expression of Rho GTPases in sperm has been conserved throughout mammalian evolution, most likely due to the role of these GTPases in regulating acrosomal exocytosis.
    Materialart: Online-Ressource
    ISSN: 0967-1994 , 1469-8730
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 2006
    ZDB Id: 1483381-5
    SSG: 12
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  • 5
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 2015
    In:  International Journal of Astrobiology Vol. 14, No. 1 ( 2015-01), p. 27-32
    In: International Journal of Astrobiology, Cambridge University Press (CUP), Vol. 14, No. 1 ( 2015-01), p. 27-32
    Kurzfassung: In the frame of the EXPOSE-R mission outside the Russian Zvezda Module of the International Space Station (ISS) passive thermoluminescence dosimeters were applied to measure the radiation exposure of biological samples. The detectors were located beneath the sample carriers to determine the dose levels for maximum shielding. The dose measured beneath the sample carriers varied between 317 ± 10 and 230 ± 2 mGy, which amount to an average dose rate of 381 ± 12 and 276 ± 2 μGy d −1 . These values are close to those assessed for the interior of the ISS and reflect the high shielding of the biological experiments within the EXPOSE-R facility. As a consequence of the high shielding (several g cm −2 ), the biological samples were predominantly exposed to galactic cosmic heavy ions and trapped protons in the Earth's radiation belts, whereas the trapped electrons did not reach the samples.
    Materialart: Online-Ressource
    ISSN: 1473-5504 , 1475-3006
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 2015
    ZDB Id: 2079707-2
    SSG: 12
    SSG: 16,12
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 2008
    In:  Oryx Vol. 42, No. 02 ( 2008-4)
    In: Oryx, Cambridge University Press (CUP), Vol. 42, No. 02 ( 2008-4)
    Materialart: Online-Ressource
    ISSN: 0030-6053 , 1365-3008
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 2008
    ZDB Id: 2020801-7
    SSG: 12
    SSG: 23
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 1992
    In:  Bulletin of Entomological Research Vol. 82, No. 4 ( 1992-12), p. 441-448
    In: Bulletin of Entomological Research, Cambridge University Press (CUP), Vol. 82, No. 4 ( 1992-12), p. 441-448
    Kurzfassung: Four dispersal phases occur during larval development of Chilo partellus (Swinehoe) on young host plants, phase 1, ballooning of newly hatched larvae when moving from egg batch to plant whorl, phase 2, ballooning of first and second instars which leave the plant whorl in the week after egg eclosion, phase 3, walking prior to stem penetration, and phase 4, walking after stem penetration. In laboratory experiments larval dispersal was density dependent during dispersal phases 1, 3 and 4 and there were clear differences between maize and sorghum in the percentage of migrating lavae and time of migration. Maize plants accommodated many more pupae than sorghum plants which suggests that the distribution of older larvae in the field can be more clumped in maize than in sorghum. Pupal weight descreased with infestation level on sorghum but seemed less affected on maize. Resistance to starvation in four combinations of temperature and relative humidity increased with age. All hatchlings survived six hours′ starvation but with considerably reduced crawling capacity. Seven- and 15-day old larvae were descreasingly affected. Older larvae survived and maintained their mobility after 48 hours. Successful dispersal will depend on host-plant, egg load, and costs of migration; these costs will change with larval age.
    Materialart: Online-Ressource
    ISSN: 0007-4853 , 1475-2670
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 1992
    ZDB Id: 1496538-0
    SSG: 12
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  • 8
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 2005
    In:  The Lichenologist Vol. 37, No. 6 ( 2005-11), p. 481-483
    In: The Lichenologist, Cambridge University Press (CUP), Vol. 37, No. 6 ( 2005-11), p. 481-483
    Kurzfassung: Strigula muscicola Berger, Coppins, Cl. Roux & Sérus. is described as new to science; it is a muscicolous species with aggregated ascomata and 3-septate ascospores, growing in subalpine habitats in Austria, Norway and Scotland.
    Materialart: Online-Ressource
    ISSN: 0024-2829 , 1096-1135
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 2005
    ZDB Id: 1471008-0
    SSG: 12
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  • 9
    In: Oryx, Cambridge University Press (CUP), Vol. 44, No. 2 ( 2010-04), p. 285-292
    Kurzfassung: The global population of saiga Saiga tatarica , categorized as Critically Endangered on the IUCN Red List, declined by 〉 95% at the end of the 20th century, resulting in several conservation initiatives to protect the species. Previously used methods to monitor population trends were inadequate to assess numbers of saiga properly. We report findings from the first survey for Mongolian saiga S. tatarica mongolica to utilize statistically rigorous methodology, using line transect distance sampling in 2006 and 2007 to obtain population estimates in and around the Sharga Nature Reserve, the southern part of the species' current range. We estimate a density of 0.54 and 0.78 saiga km -2 in 2006 and 2007, respectively. Our best models suggest that 4,938 (95% confidence interval, CI = 2,762–8,828) saiga occupied the 4,524-km 2 study area in 2006 and 7,221 (95% CI = 4,380–11,903) occupied the 4,678-km 2 study area in 2007. Although these estimates, with their large confidence intervals, preclude an assessment of the impacts of conservation initiatives on population trends, they suggest that the Mongolian saiga population is larger than previous reports based on minimum counts, and adequate to support in situ population recovery. Modifications to the survey protocol hold promise for improving the precision of future estimates. Distance sampling may be a useful, scientifically defensible method for monitoring saiga population trends and assessing the effectiveness of conservation efforts to stabilize and recover populations.
    Materialart: Online-Ressource
    ISSN: 0030-6053 , 1365-3008
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 2010
    ZDB Id: 2020801-7
    SSG: 12
    SSG: 23
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  • 10
    Online-Ressource
    Online-Ressource
    Cambridge University Press (CUP) ; 2013
    In:  Oryx Vol. 47, No. 2 ( 2013-04), p. 157-158
    In: Oryx, Cambridge University Press (CUP), Vol. 47, No. 2 ( 2013-04), p. 157-158
    Materialart: Online-Ressource
    ISSN: 0030-6053 , 1365-3008
    Sprache: Englisch
    Verlag: Cambridge University Press (CUP)
    Publikationsdatum: 2013
    ZDB Id: 2020801-7
    SSG: 12
    SSG: 23
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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