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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The annual epidemic spawning period of a Scottish population of Arenicola marina (L.) has been recorded over a period of 13 yr. This population spawns between mid-October and mid-November in a discrete spawning event over a period of 4 to 5 d. Endocrine manipulation experiments showed that spawning is induced in females only if sufficient titres of PMH (prostomial maturation hormone) are present in the prostomia. These levels are attained during the 2 to 3 wk prior to the natural spawning date. The East Sands, St. Andrews population always spawns during periods of spring tides regardless of tidal amplitude or whether they are full- or new-moon tides. Meteorological data, including sea-temperature data were collected for each year, and correlation of the environmental data with spawning time was attempted. Correlation of spawning times with weather patterns showed that mean daily air pressures were significantly higher during the spawning period than from September to November as a whole. Evidence also suggests that a reduction in sea temperature is required prior to spawning. A significant moderate negative correlation was found between May to July air temperatures and spawning date, suggesting that higher May to July temperatures may induce early spawning. Daily rainfall and wind speed were also lower during the spawning period, but not significantly so. These results indicate that air pressure (or changes therein) may act as a final spawning cue, and the advantages of this are discussed in relation to fertilization success. A model of the interplay between environmental parameters and the endocrine mechanisms controlling the induction of spawning is proposed. Higher than average summer temperatures may advance gametogenesis to bring the population into a state of maturity (full-size oocytes, well-developed sperm morulae), and may also advance spawning time. Once the population has completed gametogenesis, a drop in sea temperature is then required to trigger an increase in endocrine titres within the prostomium, without which spawning cannot be induced by prostomial injection. The population spawns on spring tides; however a lack of clement weather coinciding with the spring tide will result in population-wide spawning being aborted, as in 1996. Clement weather (high pressure, low rainfall and wind speed) in conjunction with spring tides permits spawning to proceed to completion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @British journal for the history of science 24 (1991), S. 377-379 
    ISSN: 0007-0874
    Source: Cambridge Journals Digital Archives
    Topics: History , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
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    Cambridge : Periodicals Archive Online (PAO)
    History of science. 21:4=54 (1983:Dec.) 369-388 
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  • 4
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    Dordrecht : Periodicals Archive Online (PAO)
    Theory and Decision. 3:1 (1972:Oct.) 79 
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theory and decision 3 (1972), S. 76-90 
    ISSN: 1573-7187
    Source: Springer Online Journal Archives 1860-2000
    Topics: Sociology , Economics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] We have cloned a cDNA for bovine lysozyme c2, a novel lysozyme characteristic of the cow stomach and expressed its protein product by secretion using its native signal sequence in the methylotrophic yeast, Pichia pastoris. A semi–continuous fermentation process used for production resulted in ...
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  • 7
    ISSN: 1432-2048
    Keywords: Embryo (tissue culture) ; Tissue culture (plant regeneration) ; Zea (plant regeneration)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the summer of 1983, immature embryos from 101 selfed inbred lines and germplasm stocks of Zea mays L. were examined for their ability to produce callus cultures capable of plant regeneration (regenerable cultures) using a medium with which some limited success had previously been obtained. Forty-nine of the genotypes (49%) produced callus which visually appeared similar to callus previously cultured and shown to be capable of plant regeneration. After five months, 38 of these genotypes were alive in culture and plants were subsequently regenerated from 35 (92%) of them. No correlation was observed between plant regeneration and callus growth rate, the vivipary mutation (genes vp1, 2, 5, 7, 8 and 9), or published vigor ratings based on K+ uptake by roots. When F1 hybrid embryos were cultured, 97% of the hybrids having at least one regenerable parent also produced callus capable of plant regeneration. No regenerable cultures were obtained from any hybrid lacking a parent capable of producing a regenerable callus culture. In the summer of 1984, immature embryos from 218 additional inbred lines and germplasm stocks were plated and examined for their ability to produce regenerable callus cultures on media containing altered micronutrient concentrations, 3,6-dichloro-o-anisic acid (dicamba), glucose, and elevated levels of vitamin-free casamino acids and thiamine. Of these genotypes 199 (91%) produced callus that was regenerable in appearance. In the 1984 study, plant regeneration was noted in many commercially important inbreds, including B73, Mo17, B84, A632, A634, Ms71, W117, H993H95 and Cm105. Thus tissue-culture techniques are now available to obtain callus cultures capable of plant regeneration from immature embryos of most maize genotypes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used human β2 and β4 cDNA probes to map the genes encoding two isoforms of the regulatory β subunit of voltage-activated Ca2+ channels, viz. CACNB2 (β2) and CACNB4 (β4), to human chromosomes 10p12 and 2q22-q23, respectively, by fluorescence in situ hybridization. The gene encoding the β2 protein, first described as a Lambert-Eaton myasthenic syndrome (LEMS) antigen in humans, is found close to a region that undergoes chromosome rearrangements in small cell lung cancer, which occurs in association with LEMS. CACNB2 (β2) and CACNB4 (β4) genes are members of the ion-channel gene superfamily and it should now be possible to examine their loci by linkage analysis of ion-channel-related disorders. To date, no such disease-related gene has been assigned to 10p12 and 2q22-q23.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2242
    Keywords: Transposable elements ; Activator ; Maize ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Somaclonal variation (tissue culture-induced mutations) may result, in some instances, from the activation of transposable elements. This study was conducted to determine whether somaclonal variants in the Zea maize L. inbred line FR27rhm were associated with movement of the transposable element Activator (Ac). Ten variants, seven of which from genetic analyses fit a single recessive gene model and three which did not due to a low number of mutant plants, were selected for analysis. Total DNA from these and from uncultured FR27rhm seedlings were examined by Southern blot analysis using the internal 1.6-kb Hind III fragment derived from the cloned Ac7 element as a probe. By using a restriction endonuclease which does not cut within the element, the number and distribution of the copies of Acrelated sequences in the FR27rhm genome could be determined. From the number of bands seen in the blots, we conclude that the FR27rhm inbred contains large numbers of Ac -related sequences. However, the pattern of bands seen in the ten variants and in the uncultured seedlings were identical, indicating that there had been no movement of any of the Acrelated sequences to cause the tissue culture-induced mutations.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 28 (1993), S. 2815-2819 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The following account describes investigations of dimensional and stiffness characteristics of representative polyacrylic and silicone rubbers over the approximate temperature range 20 °C–175 °C. The results have led to a quantitative understanding of distinctive features in the behaviour of these elastomers, encountered during the course of their repeated use as tool materials in composite component manufacture, conforming with an explanation in terms of thermally induced cross-linking. It is concluded that silicone rubber offers more promise than polyacrylic rubber in applications where behavioural stability and a reasonable degree of control are required.
    Type of Medium: Electronic Resource
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