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  • 1985-1989  (1)
  • 1955-1959  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 183 (1959), S. 326-326 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In certain micro-organisms, shikimic acid has been demonstrated to be in the direct path to aromatic ring biosynthesis5. Microbial response to exogenous quinic acid has been reported in secondary mutants of Aerobacter which grew well when supplied with quinic acid5. Similar results have been ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The iguanid lizard Sceloporus grammicus has a high level of karyotypic variability, and has often been cited as an example of chromosomal speciation. We examined a total of 2036 secondary spermatocytes from 30 S. grammicus males, and found that 16 of the 30 individuals (including a single lizard collected from a hybrid zone between two chromosome races) produced completely balanced spermatocytes. Fourteen of the 30 lizards (including both chromosomal heterozygotes and homozygotes) had relatively low (0.6% to 7.1%) levels of aneuploidy. Heterozygotes had a 1.1% increase over homozygotes in the number of aneuploid spermatocytes observed. The frequency of aneuploidy in S. grammicus may not be high enough to cause chromosomal speciation by any of the mechanisms that have been proposed for this complex. Most individuals showed balanced segregation of the autosomal trivalents, but nearly half of the lizards had a significant excess of spermatocytes with the X1 and X2 rather than the Y sex chromosomes. Five lizards had spermatocytes which had fission mutations not found in the somatic cells. As many as 5.9% of the spermatocytes in one individual had chromosomal mutations. This chromosomal mutation rate has important implications for chromosomal evolution in S. grammicus.
    Type of Medium: Electronic Resource
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