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  • Bacillus acidocaldarius  (2)
  • Pollen  (2)
  • Springer  (4)
  • Geological Society of America (GSA)
  • Geological Society of London
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 10 (1997), S. 236-240 
    ISSN: 1432-2145
    Keywords: Key words Cucurbita texana ; Pollen ; Pollen performance ; Pollen competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We examined the effects of pollen competition (pollen load size) on sporophytic vigor and gametophytic performance in Cucurbita texana, a wild gourd, while controlling for alternative interpretations of the data. Under field conditions we compared the vigor of progeny produced from large and small pollen loads and examined the in vitro performance of the pollen produced by the progeny. We found that the progeny from large pollen loads germinated faster and had a greater reproductive output (male flowers and fruits) than progeny produced from small pollen loads. In addition, we found that the pollen produced on plants derived from large pollen loads grew faster in vitro than the pollen produced on plants derived from small pollen loads. These findings indicate that pollen competition affects the performance of the resulting sporophytic generation and the microgametophytes they produce.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2145
    Keywords: Pollen ; microgametophyte ; soil phosphorus ; pollen competition ; pollen performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine the effects of soil phosphorus on pollen production, pollen grain size, phosphate concentration per pollen grain, and the siring ability of pollen, two cultivars of the common zucchini (Cucurbita pepo) were grown under two soil phosphorus conditions in an experimental garden. Overall, soil phosphorus availability had a significant effect on reproductive output through the female function and on traits affecting the male function of plants (staminate flower production, pollen production per flower, and pollen grain size). In addition, pollen produced by plants in the high phosphorus soils had a higher phosphate concentration than pollen produced by plants in the low phosphorus soils. A pollen mixture experiment revealed that pollen produced by plants in the high phosphorus treatment sired significantly more seeds than pollen produced by plants in the low phosphorus treatment. This study showed that growing conditions such as soil phosphorus can influence the size of a pollen grain and its chemical composition, which, in turn, can affect its ability to sire mature seeds.
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  • 3
    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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  • 4
    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).
    Type of Medium: Electronic Resource
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