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  • Articles  (6)
  • Temperature and pH  (2)
  • Bio-electrical impedance  (1)
  • Catalpa speciosa  (1)
  • Development  (1)
  • Key words Swallow  (1)
  • Springer  (6)
  • American Chemical Society
  • American Meteorological Society
  • American Physical Society
  • Amsterdam : Elsevier
  • Blackwell Science, Ltd
  • Elsevier
  • Institute of Physics
  • Seismological Society of America
  • Springer Nature
  • Wiley
  • 2000-2004  (2)
  • 1980-1984  (4)
Collection
  • Articles  (6)
Keywords
Publisher
  • Springer  (6)
  • American Chemical Society
  • American Meteorological Society
  • American Physical Society
  • Amsterdam : Elsevier
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Years
  • 2000-2004  (2)
  • 1980-1984  (4)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 210 (2000), S. 157-161 
    ISSN: 1432-041X
    Keywords: Key words Swallow ; bicoid ; Drosophila ; mRNA localization ; Oogenesis ; Embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We analyzed a functional homologue of the swallow gene from Drosophila pseudoobscura. The swallow gene of D. melanogaster plays an essential role in localizing bicoid mRNA in oocytes, and swallow mutant embryos show anterior pattern defects that result from the lack of localization of the bicoid morphogen. The pseudoobscura homologue rescues the function of swallow mutants when introduced into the genome of D. melanogaster, and its expression is similar to that of the melanogaster gene. The predicted pseudoobscura and melanogaster proteins are 49% identical and 69% conserved. The coiled-coil domain previously identified in the melanogaster swallow protein is strongly conserved in the pseudoobscura homologue, but the weak similarity of the melanogaster swallow protein to the RNP class of RNA-binding proteins is not conserved in the pseudoobscura homologue. These and other observations suggest a structural role for swallow in localizing bicoid mRNA, perhaps as part of the egg cytoskeleton.
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  • 2
    ISSN: 1432-072X
    Keywords: Molar growth yields ; Thermoacidophile ; Respiratory chain energy conservation ; Membrane permeability ; Temperature and pH ; Bacillus acidocaldarius
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The molar yield coefficients (Y glucose, Y O 2) of glucose-limited continuous cultures of the thermoacidophile Bacillus acidocaldarius have been measured as a function of dilution rate as well as over a range of temperature and pH (51°C to 64°C, pH 2.8–5.5) at a fixed dilution rate of approximately 0.1 h-1. The highest growth yields were observed at 51°C and pH〉4.3 (Y glucose 54.8 g cells · mol glucose-1, Y O 2 15.0 g cells · mol O 2 -1 ), but were very much lower than those of mesophilic neutrophiles of similar respiratory chain composition to B. acidocaldarius. Even lower growth yields were observed when the temperature was raised or when the pH was lowered, lowest yields occurring at 64°C and pH 2.8 (Y glucose 23.4 g cells · mol glucose-1, Y O 2 5.9 g cells · mol O 2 -1 ). These decreases in growth yield could be correlated with increases in the permeability of the cytoplasmic membrane to protons, i.e. cells needed to catalyse enhanced rates of substrate oxidation in order to avoid a potentially lethal acidification of the cytoplasm. This strategy appears to be successful in that the specific death rates in situ were very low for all cultures except those growing under the most extreme conditions (64°C, pH 2.8).
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  • 3
    ISSN: 1432-072X
    Keywords: Bacillus acidocaldarius ; Response surface analysis ; Temperature and pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A minimal-salts medium has been optimised to support the growth of the acidophilic thermophilic bacterium Bacillus acidocaldarius. This medium was used during a study of the effect of temperature and pH on the growth rate and growth yield of this organism in batch cultures; a statistical method was used to design the experimental points, and the data were subjected to a response surface analysis which allowed the growth rate and growth yield to be predicted over the entire temperature and pH range from a minimum number of experimental points. The results indicate different responses for growth rate (optimum, 60°C, pH 4.1) and growth yield (optimum tending towards low temperature and neutral pH).
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  • 4
    ISSN: 1573-5052
    Keywords: Clustering ; Data-processing ; Michigan ; Numerical method ; Phytosociology ; Stratum ; Understory ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During May and June, 1974, relevés were obtained from 30 plantation stands in the Saginaw Forest in southeastern Michigan. The canopy trees in these plantations were planted between 1904 and 1938. The understory has developed naturally over the years. The forest plantations offer opportunities for study of the effects of the canopy on the structure and species composition of the understory. A new numerical method of data structuring was used, which is based on the detection patterns of associated species within the table of 30 relevés from Saginaw Forest plantations. The method employs two difference measures. DIF 1 uses presence/absence data and DIF 2 the cover/abundance values obtained from the relevés. Both difference measures supply distance values for every pair of relevés. The least dissimilar relevés are then grouped together by the farthest neighbor agglomerative algorithm of Lance & Williams (1967). The DIF 1 analysis was inconclusive, but the DIF 2 analysis gave coherent results. It has shown that relevés with similar canopies have similar understories. The differences in understories among the relevés are due less to species composition than to the relative abundances of the species.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 8 (1982), S. 1025-1034 
    ISSN: 1573-1561
    Keywords: Catalpa speciosa ; catalpol ; catalposide ; iridoid glycosides ; nectar thieves ; pollination ; toxic nectar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The floral nectar ofCatalpa speciosa has a chemical mechanism that limits thievery. A bioassay employing sphingid larvae,Ceratomia catalpae, shows that catalpa iridoid glycosides are present in the floral nectar. When potential nectar thieves are fed nectar, a sucrose solution of identical concentration, or a sucrose solution plus 0.4% catalpol and 0.4% catalposide (catalpa iridoids), the thieves drink significantly more of the pure sucrose solution than either of the other two sugar sources. Those thieves that drink either the nectar or the sucrose solution plus catalpa iridoids develop behavioral abnormalities including regurgitation and loss of locomotion. The response of the potential nectar thieves to nectar or the sucrose solution plus catalpa iridoids cannot be distinguished by the amount consumed or by their behavior. The legitimate diurnal pollinators ofC. speciosa are not affected by the iridoid glycosides.
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  • 6
    ISSN: 1741-0444
    Keywords: Virtual biopsies ; Barrett's oesophagus ; Bio-electrical impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It has previously been shown that it is possible to differentiate between squamous and columnar epithelia in rat and resected human tissues using an impedance probe to makein vitro measurements. This probe can be passed down an endoscope allowing measurements to be made in patients. However, the probe emerges parallel to the oesophageal wall, with little room to manoeuvre. The conditions of control required to give reliable readings have been investigated. The importance of pressure applied and the angle of approach to the oesophagus was assessed. Pressures in the range 26.6 Pa to 46.3 kPa and angles in the range 15–90 degrees were considered. Inin vitro studies it was observed that it was possible to obtain consistent readings with pressures greater than 2.9 kPa and with angles greater than 15 degrees between the probe and the oesophagus. These conditions can be achievedin vivo, and readings obtained from twelve patients are shown (45 readings on normal squamous, 34 on Barrett's oesophagus and 22 on stomach). At low frequencies (9.6–153.2 kHz), a Mann-Whitney test shows a significant difference (p〈0.001) when comparing the means from squamous and columnar, and also when readings from Barrett's and normal gastric epithelia are compared (p〈0.001).
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