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  • 1
    Electronic Resource
    Electronic Resource
    A new interpretation of the sex determining mechanism of the European earwig,Forficula auricularia (1970)
    Springer
    Cellular and molecular life sciences 26 (1970), S. 1387-1389 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Riassunto Osservazioni su femmine diForficula auricularia L. indicano che esse possiedono un solo cariotipo formato da 22 autosomi e da 2 cromosomiX. Sulla base di questo studio, suggeriamo che i maschi con 3 cromosomi sessuali sono del tipoXYY, e nonXXY come precedentemente ritenuto da varii autori. Ci sono maschiXY 1t, XY2, XY2Y2 e mosaiciXY 2/XY2Y2 nella popolazione. Inoltre viene dimostrato che solamente il più grande dei due cromosomi Y, che caratterizzano questa specie, viene accumulato nei maschi con un meccanismo multiple di cromosomi sessuali.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02113049
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  • 2
    Electronic Resource
    Electronic Resource
    Cytogenetics of the grasshopper Moraba scurra (1963)
    Springer
    Chromosoma 14 (1963), S. 140-145 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cytology of a male individual of the grasshopper Moraba scurra which was heterozygous for a complex translocation involving breaks in four different, non-homologous, chromosomes, is described. Chains of up to eight chromosomes occur at first metaphase. Certain chromosomes which never normally show more than a single chiasma form two chiasmata with a fairly high frequency in this individual.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336755
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  • 3
    Electronic Resource
    Electronic Resource
    Chiasmatic and achiasmatic meiosis in African Eumastacid grasshoppers (1965)
    Springer
    Chromosoma 16 (1965), S. 271-307 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Male meiosis follows an entirely normal course in six species of the grasshopper genus Amatonga (Eumastacidae, Euschmidtiinae). 2. In twenty-four species of the Eumastacid subfamily Thericleinae the usual diplotene and diakinesis stages are omitted completely in the male sex, the transition from pachytene to prermetaphase being direct and apparently very rapid. 3. In some of these species chiasmata become visible at the beginning of first metaphase, when the spindle is established. In others the early metaphase bivalents are worm-like structures in which no chiasmata can be seen until mid-metaphase, when the chiasmata are suddenly revealed as loops open out between them. We call the latter type of meiosis cryptochiasmate. 4. In three species of the genus Thericles chiasmata are never seen in the male, even in late metaphase, and observations on first anaphase make it quite improbable that crossing-over has occurred. However, only observation of structurally heterozygous bivalents (which do not occur naturally in these species) will decide this question for certain. 5. In the species which most clearly lacks chiasmata in the male the chromosomes in the oocyte show clear chiasmata (oogenesis has not been studied in the other species).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325995
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  • 4
    Electronic Resource
    Electronic Resource
    Sex chromosomes and meiotic mechanisms in some African and Australian Mantids (1965)
    Springer
    Chromosoma 16 (1965), S. 521-547 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Species of the genus Compsothespis have an X1X2Y trivalent in the male with both ends of the X2 chromosome associated with the same end of the Y. This X1X2Y mechanism must have had an independent origin from the one found in the Mantinae sensu stricto. 2. A second species of Rhodomantis has been shown to have an X1X2Y trivalent in which X1 and X2 are associated with the same limb of the Y, leaving the other limb free. The sex chromosome mechanisms of Compsothespis and Rhodomantis both imply the existence of triple synaptic segments. 3. The genera Bolbe, Ligaria, Hoplocorypha, Antistia, Dystacta, Bisanthe and Harpagomantis have XO males. 4. A species of Dystacta is polymorphic for a pericentric inversion. A species of Hoplocorypha and one of Antista are polymorphic for fusions or dissociations. 5. The genera Sphodropoda, Polyspilota and Archimantis belong to the group of X1X2Y Mantinae sensu stricto. It has been shown that those members of this group which have very small Y-chromosomes have the pairing limbs of the X1 and X2 chromosomes unusually long; it is probable that this situation is due to translocations having occurred whereby material was transferred from the Y to the X's. 6. Bolbe and Harpagomantis are added to the list of mantid genera with achiasmatic meiosis (Callimantis-type) in the male. Achiasmatic meiosis has probably been evolved at least five times in the phylogeny of the mantids. 7. Some comparisons are made between the achiasmatic mechanisms which have evolved in certain mantid genera and in a few species of Thericleine Eumastacid grasshoppers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326972
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  • 5
    Electronic Resource
    Electronic Resource
    Asymmetry of heteropycnosis in tetraploid cells of a grasshopper (1970)
    Springer
    Chromosoma 30 (1970), S. 51-61 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In XO male grasshoppers (Acridoidea and Eumastacoidea) X-chromatin is negatively heteropycnotic in spermatogonial mitoses. In neo-XY species which have a fusion between the original X and an autosome it is usual for the former alone to show negative heteropycnosis. This is the case in the Australian Morabine grasshopper species “P52a”. In tetraploid spermatogonia of this species, however, which contain two neo-X's and two neo-Y's, only one of the neo-X's has a negatively heteropycnotic left limb, the other X having the same degree of condensation as the autosomes. This novel type of behavior is compared with the heteropycnosis of one of the two X's in the somatic cells of female mammals. It is concluded that the asymmetry of condensation of the two X's in tetraploid spermatogonia of “P52a” demonstrates the existence of a fundamental cellular mechanism which is inherent and only expressed under the abnormal condition of tetraploidy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293909
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  • 6
    Electronic Resource
    Electronic Resource
    Karyotypes and meiotic mechanisms of some eumastacid grasshoppers from East Africa, Madagascar, India and South America (1970)
    Springer
    Chromosoma 30 (1970), S. 62-97 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Five species of the subfamily Thericleinae from East Africa show various types of “cryptochiasmatic” meiosis in the male, in which the chiasmata are not visible in prophase and are only revealed in the course of first metaphase. Several of these species have very large chromosomes. Two species belonging to the subfamily Miraculinae, from Madagascar have 2 n♂=25 acrocentric chromosomes, the highest number known in the Eumastacidae. Their meiosis is of the normal type. — Eighteen species of the subfamily Pseudoschmidtiinae, also from Madagascar have, for the most part, small chromosomes and a very uniform karyotype, of 2 n♂=21 acrocentrics. A species of Xenomastax has acquired an X1X2Y sex chromosome mechanism as a result of two successive chromosomal fusions. A fusion beween autosomes has reduced the chromosome number to 2 n♂=19 in the genus Tetefortina. The male meiosis of the Pseudoschmidtiinae is quite orthodox. — Two species of Eumastacids belonging to the subfamily Mastacideinae, from South India, show 2 n♂=21 acrocentrics. The male meiosis is quite orthodox, with a rather high chiasma frequency. — Three South American species of Eumastacidae, belonging to the subfamilies Paramastacinae, Parepisactinae and Eumastacinae respectively, have karyotypes which seem to be very different from those of the Old World subfamilies that have been studied. Meiosis is normal. The cytological evidence thus confirms the view of systematists that the evolutionary divergence of the subfamilies of Eumastacidae is very considerable, and presumably ancient. As far as we can tell, each subfamily may be characterized by a typical or primitive karyotype. There have been fewer evolutionary fusions of chromosomes in the Thericleinae and Pseudoschmidtiinae than in the Morabinae and no chromosomal dissociations are known to have occurred in the two former subfamilies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293910
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  • 7
    Electronic Resource
    Electronic Resource
    The chromosomes of Hemimerus bouvieri chopard (Dermaptera) (1971)
    Springer
    Chromosoma 34 (1971), S. 183-189 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The parasitic insect Hemimerus bouvieri, of rather uncertain systematic position but probably an aberrant member of the order Dermaptera, shows 2n ♂=7, 2n ♀=8. The chromosomes appear to be holocentric. There is an X1X2Y sex chromosome mechanism in the male, and a sex-trivalent is formed at meiosis. The two autosomal bivalents seem to be chiasmate and the members of the sex-trivalent may also be held together by chiasmata, but this is uncertain. In general, these cytological features are similar to those of true earwigs (Forficulina).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285185
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  • 8
    Electronic Resource
    Electronic Resource
    Cytogenetics of the parthenogenetic grasshopper Warramaba (formerly Moraba) virgo and its bisexual relatives (1978)
    Springer
    Chromosoma 67 (1978), S. 309-339 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The karyotypes of Warramaba virgo and the two bisexual species which gave rise to it, by hybridization, have been studied by the C- and G-banding techniques. W. virgo consists of a number of clones which differ by a limited number of inversions, translocations and fusions and also in C-banding pattern. In general, each local population consists of a single clone, although instances are known where two clones exist at the same locality. A total of fifteen cytological clones are here recognised and described. Some of these are known from single localities, while others have been found at several collecting sites in the same general area. The differences between them in banding pattern are relatively minor, i.e. the architecture of the karyotype has been highly conserved. A total of 50 C-bands have been recognised in W. virgo, but some of these are only present in a single clone and most clones have 39–40 bands. Most of these are centromeric or interstitial; a few are terminal (telomeric) in the short arms. There are three types of bands, dark-staining centromeric ones, intermediate ones that are somewhat less densely staining, and lighter ones that appear “grey” even after successful C-banding. The C-banding pattern of W. virgo provides additional evidence for its origin by hybridization between the bisexual species “P196” and “P169”. It is possible that W. virgo arose only “once” (i.e. from one or more matings between P196 and P169 individuals in the same deme, within a few generations). However, two clones (Zanthus and Boulder), which are themselves closely similar, differ so much in banding pattern from all others that they may have arisen independently.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00285964
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  • 9
    Electronic Resource
    Electronic Resource
    Evidence for Polyploidy in the Hermaphrodite Groups of Animals (1940)
    [s.l.] : Nature Publishing Group
    Nature 146 (1940), S. 132-133 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IT is now well known that a large number of species of higher plants are polyploids, and it is reasonable to infer that polyploidy has been one of the main evolutionary methods of species formation in the angiosperms. In animals a few instances of polyploidy are known in parthenogenetic forms ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/146132a0
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  • 10
    Electronic Resource
    Electronic Resource
    Chromosome Cycle of Ascaris megalocephala (1936)
    [s.l.] : Nature Publishing Group
    Nature 137 (1936), S. 783-783 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] PAINTER1 and Schrader2 have recently suggested that the long chromosomes of the germ-line cells in Ascaris megalocephala are peculiar in having a large number of spindle attachments instead of only one as hitherto assumed. Some time ago, I carried out an experiment ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/137783a0
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