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  • 1
    Electronic Resource
    Electronic Resource
    Cell Size, Macromolecule Composition, Nuclear Number, Oxygen Consumption and Cyst Formation During Two Growth Phases in Unagitated Cultures of Acanthamoeba castellanii (1969)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 16 (1969), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. The size, composition and physiology of average cells have been studied in cultures of Acanthamoeba castellanii during the phases of logarithmic growth and population growth deceleration (PGD). Most of the features examined were relatively constant during log phase, but had significant changes during PGD. Average cell volume increased about 60% and total dry mass about 15–20% during the latter period. Total protein content remained constant thruout both growth phases, but cytochrome oxidase doubled during PGD. DNA, RNA and glycogen levels began to change during late log phase. DNA decreased about 50% and RNA increased about 75%. Glycogen decreased 50% during the RNA build-up and then increased to a plateau above the log phase level. A final decrease in glycogen followed an increase in the relative numbers of cysts in late PGD.It was found that PGD begins when O2 becomes limiting and evidence that the subsequent changes in macromolecule composition are related to encystation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1969.tb02329.x
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  • 2
    Electronic Resource
    Electronic Resource
    High-resolution laser spectroscopy of theQ v(0) transitions in solid parahydrogen (1994)
    Springer
    Applied physics 59 (1994), S. 265-281 
    Details
    ISSN: 1432-0649
    Keywords: 78.30.Hv ; 61.80.Ed ; 78.20.Jq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Our recent high-resolution laser spectroscopy of theQ v(0) (υ=υ←0,J=0←0) transitions in solid parahydrogen is discussed. The systems studied include the fundamental vibrational bands of impurity D2 and HD, the first and second overtones of parahydrogen, and the charge-induced spectrum ofγ-ray irradiated parahydrogen. Additionally, Stark and stimulated Raman-gain spectroscopies are applied to the solid. The linewidths are as sharp as 2 MHz HWHM, which is highly unusual for a solid. Our spectra demonstrate a variety of physical phenomena, particularly theΔk = 0 selection rule, as well asJ = 1/J = 0 pair intermolecular interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01081395
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  • 3
    Electronic Resource
    Electronic Resource
    Group-I introns with unusual sequences occur at three sites in nuclear 18S rRNA genes of Acanthamoeba lenticulata (1998)
    Springer
    Current genetics 34 (1998), S. 71-78 
    Details
    ISSN: 1432-0983
    Keywords: Key words Group-I introns ; Ribosomal DNA ; Acanthamoeba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven of eleven isolates of Acanthamoeba lenticulata were found to have group-I introns located at one of three positions within the 18S rRNA gene. The introns are 636–721-bp long and are absent from mature rRNA. They lack open reading frames that could encode any known endonucleases. Sequences of introns from the same site in different isolates are 86.0–98.9% identical, while from different sites they are 24.2–29.8% identical. The most closely related introns from other organisms are in the 18S rRNA genes of several green algae where the 17.0–23.6% identity is mostly limited to a highly conserved core of base pairs including P, Q, R and S. Because the A. lenticulata introns only occur in one Acanthamoeba lineage, they were probably acquired after the divergence of this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050368
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  • 4
    Electronic Resource
    Electronic Resource
    Direct measurement of the crystal field splitting of isolated J=1 impurities in solid parahydrogen (1996)
    Springer
    Journal of low temperature physics 102 (1996), S. 241-247 
    Details
    ISSN: 1573-7357
    Keywords: 33.70 Cfj ; 33.20 E ; 78.30 J
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The crystal field splitting of single J=1 impurity orthohydrogen molecules in an otherwise pure J=0 parahydrogen crystal has been studied experimentally and theoretically over many years. We have measured this quantity directly from the fine structure of the Q3 (0) (v = 3← 0, J = 0← 0) overtone transition induced by J=1 hydrogen, in the near infrared using a Ti:sapphire laser. From our observed eight pairs of split spectral lines, we have determined the value Δ/k = [E(M=±1) − E(M=0)]/k = 0.0102 ± 0.0003 K including its sign. A straightforward numerical calculation based on ab initio calculations of the H2-H2 potential reproted by Mulder, van der Avoird, and Wormer gives Δ/k = 0.0116 K which is close to the experimental value. This suggests that the static and dynamic effects of phonons on the splitting may have been overestimated in the past.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754660
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  • 5
    Electronic Resource
    Electronic Resource
    The induction of multinuclearity in agitated and in aging cultures of Acanthamoeba sp. neff (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 70 (1967), S. 53-61 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Unagitated cultures of Acanthamoeba in the logarithmic growth phase have been observed to consist of over 99% mononucleates and less than 1% multinucleates. A small increase in the relative numbers of multinucleates occurs as the culture age and conditions for growth become limiting. A large increase in the proportion of multinucleates occurs during logarithmic growth, if the cultures are agitated by shaking or by the bubbling from a stream of air. After an initial increase and until the end of logarithmic growth, the numbers of multinucleates in the agitated cultures are maintained at a constant fraction of the total population. Proportions of multinucleates as high as 25% are observed during this period. A second increase in the relative numbers occurs as conditions for growth become limiting. Under these conditions, the multinucleates may exceed 50% of the total population. The factors inducing multinuclearity as well as the kinetics of the mononucleate and multinucleate accumulation curves are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040700108
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    Paper (German National Licenses)
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