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  • 1960-1964  (3)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Chromosomal uniformity in the avian subclass Carinatae (1964)
    Springer
    Chromosoma 15 (1964), S. 280-288 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. A method for making two-dimensional measurements of colchicinized metaphase chromosomes was applied to six avian species and one interfamilial hybrid of the subclass Carinatae: the canary (Serinus canarius, 2n=80±), the parakeet (Melopsittacus undulatus, 2n=58±), the pigeon (Columba livia domestica, 2n= 80±), the turkey-pheasant hybrid (♂ Meleagris gallopavo × ♀ Phasianus colchicus, 2n=80±), the Japanese quail (Coturnix coturnix japonica, 2n=78 ±), the jungle fowl of Java (Gallus gallus bankivo, 2n=78 ±), and the duck (Anas platyrhyncha domestica, 2n=80 ±). 2. In these species representing five different orders of diverse geographic origin, the total chromosome area varied only from 62.42 μ 2 in the turkey-pheasant hybrid to 67.95 μ 2 in the parakeet. 3. The absolute size of the Z-chromosome was equally uniform, ranging only from 2.3 μ 2 in the pigeon and duck to 3.0 μ 2 in the canary. A W-chromosome two-thirds as large as the Z was noted in the female canary and pigeon; thus the sex chromosome constitution of the heterogametic sex in all avian species is probably ZW, not ZO. 4. Class Aves, subclass Carinatae, constitutes an independently uniform class with regard to the total chromosome area and the absolute size of the Z-chromosome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321513
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Close karyological kinship between the reptilian suborder serpentes and the class aves (1964)
    Springer
    Chromosoma 15 (1964), S. 606-617 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In contrast to the situation found in two classes of warm-blooded vertebrates, mammals and birds, the class Reptilia is not uniform with regard to total genetic content; rather, it contains two distinct categories. The close cytological kinship between snakes and birds was revealed. Both are almost identical in total genetic content, which is about 50 per cent that of placental mammals. Both have microchromosomes, as well as Z-chromosomes very similar in absolute size, comprising nearly 10 per cent of the homogametic haploid (AZ) set. This leads to the implication that snakes and birds originated from the same lineage, and that their Z-chromosomes have not changed substantially since the Jurassic period of the Mesozoic era, about 180 million years ago. Within the reptilian suborder Serpentes, the step-by-step differentiation from the primitive ZW pair to the grossly heteromorphic ZW pair could be observed. In the ancient family Boidae, the sex chromosomes were still homomorphic to each other. In the family Colubridae, the beginning of heteromorphism was manifested in two ways. In some species, a pericentric inversion on the W caused it to differ from the Z; in others, duplication of the W occurred. In the family Crotalidae, the W had apparently achieved its very specialized status; it was a distinctly smaller element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319994
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    X-autosome ratio and the behavior pattern of individual X-chromosomes in placental mammals (1964)
    Springer
    Chromosoma 15 (1964), S. 14-30 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary From the 15 diverse species of placental mammals investigated cytologically in this laboratory, seven species and one interspecific hybrid were selected for the present study : man (Homo sapiens, 2n=46), cattle (Bos taurus, 2n=60), the cat (Felis domestica, 2n=38), the dog (Canis familiaris, 2n=78), the mouse (Mus musculus, 2n=40), the golden hamster (Mesocricetus auratus, 2n=44), the creeping vole (Microtus oregoni, 2n=17/18), and the mule (2n=63). We devised a method for making two-dimensional measurements of chromosomes which produced the following results: 1. Despite the wide variation in chromosome number, the eight species had diploid chromosome complements which appeared to contain about the same amount of genetic material, varying from 145.14 μ2 in the mouse to 165.73 μ2 in cattle. 2. The X-chromosome of the dog, the donkey, and cattle appeared to be almost identical in absolute size, ranging from 4.11 to 4.65 μ2. Although only presumptive identification of the X is possible in the cat, the mouse, man, and the horse, they too seemed to fall within the same size range (3.75–5.07 μ2). Phylogenic studies of vertebrate sex chromosomes suggest that the X in the great majority of placental mammals retains the original size and genetic constitution of a common ancestor. In the golden hamster, the X is twice this size (8.33 μ2) and is regarded as a duplicate; in the creeping vole, three times (12.70 μ2), a triplicate. In the latter species, the sex chromosome constitution of somatic cells in the normal female is XO. 3. Each of the three X-chromosome types demonstrated a distinctive behavior pattern in somatic cells. If positive heteropycnosis can be equated with genetic inertness, then all the species in this study appeared to have about the same amount of functioning X-chromosome material in diploid nuclei of both sexes. The ambivalent nature of the mammalian X apparently provides the mechanism which maintains the constant optimal ratio between the functional X and the autosomes in somatic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326912
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    Paper (German National Licenses)
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