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  • Bacillus acidocaldarius  (2)
  • Invertebrate phototransduction  (2)
  • Key words Wheat  (2)
  • LDL receptor  (2)
  • Springer  (8)
  • Geological Society of America (GSA)
Collection
Publisher
  • Springer  (8)
  • Geological Society of America (GSA)
Years
  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 94 (1997), S. 557-563 
    ISSN: 1432-2242
    Keywords: Key words Wheat ; PCR ; Microsatellite ; Simple sequence repeats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The development of large panels of simple-to-analyse genetic markers for tagging agronomically important genes and diversity studies in hexaploid bread wheat is an important goal in applied cereal genetic research. We have isolated and sequenced over 200 clones containing microsatellites from the wheat genome and have tested 153 primer pairs for genetic polymorphism using a panel of ten wheat varieties, including the parents of our main mapping cross. A subset comprising 49 primer pairs detects 76 loci, of which 74 can be unequivocably allocated to one of the wheat chromosomes. A relatively low frequency of the loci detected are from the D genome, and these loci show less polymorphism than those from the A and B genomes. Generally, the microsatellites show high levels of genetic polymorphism and an average of 3.5 alleles per locus with an average polymorphism information content (PIC), value of 0.51. The observed levels of polymorphism are positively correlated with the length of the microsatellite repeats. A high proportion, approximately two-thirds, of primer pairs designed to detect simple sequence repeat (SSR) variation in wheat do not generate the expected amplification products and, more significantly, often generate unresolvable PCR products. In general, our results agree closely with those obtained from other recent studies using microsatellites in plants.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 97 (1998), S. 946-949 
    ISSN: 1432-2242
    Keywords: Key words Wheat ; Microsatellite markers ; Genetic map
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Hexaploid bread wheat (Triticum aestivum) has low levels of RFLP. Simple sequence repeats, however, show high levels of polymorphism and are therefore especially useful in intervarietal breeding applications. We present 53 newly mapped microsatellite loci for the wheat genetic map, 41 primary loci and 12 additional loci from these same primer pairs. Markers have been accredited with a quality score on a scale of 1–5 which describes the complexity of the amplification product profile from each primer pair.
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  • 5
    ISSN: 1432-0878
    Keywords: Photoreceptors ; Ommatidia ; Tissue dissociation ; Enzymatic digestion ; Invertebrate phototransduction ; Electrophysiology ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Photoreceptor cells that were mostly free of extracellular material and suitable for most electrophysiological study procedures were dissociated from whole heads of the fruit fly, Drosophila melanogaster, by a simple “smash” technique employing gentle chopping by a razor blade through Parafilm sheets. A variety of commonly available proteolytic and glycolytic digestion enzymes were tested as additions to the basic dissociation procedure described. With the aid of Nomarski interference contrast optics, periodic acid-Schiff staining, and fluorescent labeling and microscopy methods, it was determined that proteolytic enzymatic digestion does little to enhance the dissociation procedure, and instead, often damages the cells that one is attempting to recover. Unexpectedly, certain glycolytic enzymes, when added to the basic procedure, appear to enhance the recovery of intact viable Drosophila photoreceptors that are stripped of most extracellular material. Based on these results, a hypothesis concerning the biochemical nature of the extracellular matrix of the Drosophila retina is proposed. Drosophila photoreceptors are an interesting model system for the study of invertebrate phototransduction and photoreceptor cell biology because of their many well-characterized mutant strains. The technique described here should produce clean viable photoreceptors or ommatidia that respond to light, and that are suitable for patch clamping or cell culture.
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  • 6
    ISSN: 1432-0878
    Keywords: Key words: Photoreceptors ; Ommatidia ; Tissue dissociation ; Enzymatic digestion ; Invertebrate phototransduction ; Electrophysiology ; Drosophila melanogaster (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Photoreceptor cells that were mostly free of extracellular material and suitable for most electrophysiological study procedures were dissociated from whole heads of the fruit fly, Drosophila melanogaster, by a simple ”smash” technique employing gentle chopping by a razor blade through Parafilm sheets. A variety of commonly available proteolytic and glycolytic digestion enzymes were tested as additions to the basic dissociation procedure described. With the aid of Nomarski interference contrast optics, periodic acid-Schiff staining, and fluorescent labeling and microscopy methods, it was determined that proteolytic enzymatic digestion does little to enhance the dissociation procedure, and instead, often damages the cells that one is attempting to recover. Unexpectedly, certain glycolytic enzymes, when added to the basic procedure, appear to enhance the recovery of intact viable Drosophila photoreceptors that are stripped of most extracellular material. Based on these results, a hypothesis concerning the biochemical nature of the extracellular matrix of the Drosophila retina is proposed. Drosophila photoreceptors are an interesting model system for the study of invertebrate phototransduction and photoreceptor cell biology because of their many well-characterized mutant strains. The technique described here should produce clean viable photoreceptors or ommatidia that respond to light, and that are suitable for patch clamping or cell culture.
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  • 7
    ISSN: 1435-232X
    Keywords: Key words Hyperlipoproteinemia ; Lipoproteins ; LDL receptor ; Familial hypercholesterolemia ; Genetic diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Heterozygous familial hypercholesterolemia (FH) is a serious disorder causing twice normal low-density lipoprotein (LDL) cholesterol levels early in childhood and very early coronary disease in both men and women. Treatment with multiple medications together with diet can normalize cholesterol levels in many persons with FH and prevent or delay the development of coronary atherosclerosis. Previously published blood cholesterol criteria greatly under-diagnosed new cases of FH among members of known families with FH and over-diagnosed FH among participants of general population screening. Thus, there is a need for accurate and genetically validated criteria for the early diagnosis of heterozygous FH. In the course of investigations of coronary artery disease in Utah, we identified a family whose proband showed elevated plasma levels of LDL cholesterol. To carry out molecular genetic diagnosis of the disease, we screened DNA samples for mutations in all 18 exons and the exon-intron boundaries of the LDL receptor gene (LDLR). Novel point mutations were identified in the proband: a C-to-T transversion at nucleotide position 631, causing substitution of tyrosine for histidine at codon 190 in exon 4 of the LDLR gene. The mutant allele-specific amplification method was used to examine 12 members of the family recruited for the diagnosis. This method helped to unequivocally diagnose 7 individuals as heterozygous for this particular LDLR mutation, while excluding the remaining 5 individuals from carrier status with FH.
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  • 8
    ISSN: 1435-232X
    Keywords: Key words Hyperlipoproteinemia ; Lipoproteins ; LDL receptor ; Familial combined hyperlipidemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Factors predisposing to the phenotypic features of familial combined hyperlipidemia have not been clearly defined. In the course of investigating familial coronary artery disease in Utah, we identified a three-generation family in which multiple members were affected with type IIa hyperlipoproteinemia (HLP IIa), type IIb hyperlipoproteinemia (HLP IIb), or type IV hyperlipoproteinemia (HLP IV). Because several family members had relatively severe low-density lipoprotein (LDL) cholesterol elevation, in order to dissect the possible contribution to the plasma lipoprotein abnormalities in this pedigree, we identified a novel point mutation in the low-density lipoprotein receptor (LDLR) gene, a G-to-A transition at nucleotide position 337 in exon 4. This change substituted lysine for glutamic acid at codon 92 (D92K) of the LDL receptor. By means of mutant allele-specific amplification we determined that the mutation co-segregated with elevated cholesterol and LDL cholesterol in the plasma of family members with HLP IIa and HLP IIb, but not with the elevated plasma triglycerides seen in HLP IIb and HLP IV patients. Thus, in families with apparent familial combined hyperlipidemia, a defective LDLR allele and other genetic or environmental factors that elevate plasma triglycerides may account for the multiple lipid phenotypes observed in this kindred.
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