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  • 1
    Digitale Medien
    Digitale Medien
    Some neurochemical studies on auditory regions of mouse brain (1979)
    Springer
    Experimental brain research 36 (1979), S. 573-584 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Auditory system ; GABA ; Acetylcholine ; Taurine ; Amino acids ; Neurotransmitters
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The mouse brain auditory pathway has been dissected into five regions: geniculate bodies, posterior colliculi, superior olives, cochlear nuclei, and cochleas. The following analyses were made in these regions and in the auditory cortex: protein, glutamate, γ-aminobutyrate, taurine, choline acetyltransferase, and glutamate decarboxylase. Taurine levels (nmol · mg of protein-1) were highest in cortex (93) and geniculate bodies (60) and lowest in the cochlear nuclei (27) and cochleas (29). Concentrations of γ-aminobutyrate (same units) were highest in the geniculate bodies (28), low in the superior olives and cochlear nuclei (9 to 10), and undetectable in the cochleas. The distribution of glutamate decarboxylase activity reflected that of γ-aminobutyrate. The activities of choline acetyltransferase (nmol · of acetylcholine synthesized · h · -1 mg of protein-1) were highest in the superior olives (60) and low in the cochleas (3). These results are interpreted as biochemical support for previous physiological and pharmacological identification of the olivo-cochlear bundle as cholinergic and the cochlear-nucleus neurones as non-cholinergic. The results also provide further evidence for a role of GABA in the posterior colliculi, but not in the cochleas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00238524
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  • 2
    Digitale Medien
    Digitale Medien
    Cytogenetics of the parthenogenetic grasshopper Warramaba (formerly Moraba) virgo and its bisexual relatives (1977)
    Springer
    Chromosoma 61 (1977), S. 127-148 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Triploid hybrids have been obtained by crossing individuals of the diploid Warramaba virgo with males of two undescribed related species of Warramaba, “P169” (neo-XY) and “P196” (X1X2Y). In both cases, offspring which receive a Y-chromosome from the father are males, while those that receive a neo-X from P169 or an X1 and an X2 from P196 are females. The triploids can be distinguished from diploids, even in the earliest nymphal instars, by the larger size of their eye facets. Their gonads are undeveloped and abnormal so that they are mostly sterile (the males absolutely so). Nevertheless, in the case of female hybrids (both the ones between virgo and P169 and those between virgo and P196) a few oocytes do develop and it was possible to obtain a further generation of hybrids by parthenogenesis. These, which are all female, and have karyotypes identical to those of their mothers, are derived from eggs which have undergone the virgo type of meiosis, with a premeiotic doubling of the chromosome number, followed by synapsis restricted to sister chromosomes. — Some diploid hybrids have also been obtained between the bisexual species P169 (♀) and P196 (♂). In this case the male offspring died in the embryonic stage or immediately after hatching. Female hybrids, on the other hand, were viable but had under-developed ovaries, so that they only laid very few eggs. Some of the latter developed into embryos with a karyotype identical to that of the mother, but the meiosis of these eggs has not yet been studied, so that it is not known whether it is of the virgo type. These hybridization experiments support the hypothesis that virgo originated as a hybrid between P196 and P169. — A single male hybrid between Warramaba picta (♀) and P169 (♂) was obtained; it had active spermatogenesis, but many meiotic abnormalities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00327397
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  • 3
    Digitale Medien
    Digitale Medien
    Cytogenetics of the parthenogenetic grasshopper Warramaba virgo and its bisexual relatives (1981)
    Springer
    Chromosoma 82 (1981), S. 453-469 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Cloned highly repeated DNA sequences were used to investigate the origins of W. virgo. The chromosomal and genomic organization of these sequences in the parthenogenetic grasshopper W. virgo and its sexual relatives indicate that W. virgo has had two independent origins. Data from the cloned sequences together with that from rapidly renaturing DNA are consistent with a hybridization event between two sexual species for each origin of the parthenogenetic species. Previously published data on C-banding and other karyotypic features (White and Contreras 1981) strengthen the dual origin conclusion. — The cloned DNA sequences, pWv 1 and pWv 5, have differentiated northern and southern races in the sexual species P196. The southern race appears to have hybridized with another sexual species, P169, to give rise to the Boulder/Zanthus clones of W. virgo. The northern race of P196 may have crossed with a species similar to P169 to give rise to the remaining W. virgo clones which are now present in both eastern and western Australia. White (1980) proposed that the origin of W. virgo was in western Australia and that the eastern populations were established by migration. Consistent with this hypothesis is our finding that the cloned DNA sequences have identical genomic and chromosomal organisation in populations of W. virgo in the two disjunct areas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00295006
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  • 4
    Digitale Medien
    Digitale Medien
    Cytogenetics of the parthenogenetic grasshopper Warramaba virgo and its bisexual relatives (1982)
    Springer
    Chromosoma 85 (1982), S. 181-199 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract A study of the chromosomal location and genomic organization of the ribosomal RNA cistrons in the genus Warramaba, involving in situ hybridization and restriction enzyme analysis as well as C- and N-banding and silver staining, has confirmed that the parthenogenetic species W. virgo has two phylads. These phylads appear to have originated independently by hybridization between the precursors of the present day bisexual species “P169” and “P196”. The clones of the Standard phylad of W. virgo have their 18S+26S rDNA cistrons located in C-bands 4, 44 and 49, while those of the Boulder-Zanthus phylad have them in C-bands 50, 74 and 87.5. The relative numbers of the ribosomal genes at the different sites vary greatly from clone to clone and are closely correlated with the width of the corresponding C- and N-bands. Site 49 of the ribosomal cistrons is present as a separate band in the eastern race “A” of P196 but has been incorporated into band 50 in the western race “B” of this species. The former race is assumed to be ancestral to the Standard phylad of W. virgo, the latter to the Boulder-Zanthus phylad, but there has been loss of the 74 and 87.5 sites in the the Standard phylad and the 4 and 44 sites in the Boulder-Zanthus clones. The ribosomal cistrons in W. picta, a species with a primitive karyotype, occur in several sites, only some of which have counterparts in P169 and P196. The 5S rDNA cistrons are located in bands 59.5, 69 and 72.5 in the Standard phylad of W. virgo. — The genomic organization of the 18S+26S rDNA cistrons, as shown by restriction enzyme analysis, is different in the two W. virgo phylads and there are also differences in organization between P196A and P196B. The pattern in P196B and that in the Boulder-Zanthus phylad suggest that they are related. As in the in situ analyses, the genomic organizations of the ribosomal cistrons in both W. virgo phylads are not simply the additive products of those in any known populations of P169 and P196. New repeat lengths indicative of segmental amplification events occur in particular clones of W. virgo. — Throughout the genus Warramaba the N-banding technique stains all bands containing 18S+26S and 5S rDNA cistrons. The Olert silver technique stains band 72.5 in the Standard phylad, but does not correlate with the locations of 18S+26S ribosomal genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00294964
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  • 5
    Digitale Medien
    Digitale Medien
    Cytogenetics of the parthenogenetic grasshopper Warramaba (formerly Moraba) virgo and its bisexual relatives (1978)
    Springer
    Chromosoma 67 (1978), S. 55-61 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Hybrids of both sexes were obtained from the reciprocal crosses, carried out in the laboratory, between the species believed to have given rise, by hybridization some thousands of years ago, to the parthenogenetic species W. virgo. All males with a Y-chromosome derived from P196 died before reaching the adult stage, but two males from the reciprocal cross (i.e., with a Y from P169) survived up to the adult stage. Their testes were small but normal in structure and histology. At the first meiotic division almost all the chromosomes were univalents, 0–2 bivalents being formed. Some chiasmata between non-homologous chromosomes were present. Segregation at first anaphase is irregular so that sperms with 3–15 chromosomes are formed. Such hybrids appear to be entirely sterile.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00285647
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  • 6
    Digitale Medien
    Digitale Medien
    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
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00285964
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  • 7
    Digitale Medien
    Digitale Medien
    Cytogenetics of the parthenogenetic grasshopper Warramaba (formerly Moraba) virgo and its bisexual relatives (1980)
    Springer
    Chromosoma 81 (1980), S. 213-248 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The distribution of late-replicating segments along the chromosomes of five clones of W. virgo is described. Some, but not all of these segments correspond to C-bands. In general, the “autoradiographic profiles” (histograms of linear grain density along the length of chromosomes labeled with tritiated thymidine in late S-phase) show strong resemblances throughout the five clones. However, some significant differences exist, and these are particularly marked in the case of the Boulder clone, which is anomalous in many other respects. — A similar study has also been carried out on the two bisexual species of Warramaba (“P169” and “P196”) that gave rise, by hybridization more than half a million years ago, to the parthenogenetic W. virgo. In the case of P169, the autoradiographic profiles of the three large chromosomes (X+A, B+5, CD) which it has contributed to the W. virgo karyotype are extremely similar to those of the corresponding chromosomes in the virgo clones we have studied. In the case of P196 there is likewise, in most instances, a close resemblance of the autoradiographic profiles of the AB, X1 and CD chromosomes to those of the same chromosomes in the virgo clones, but that of the X1 shows no particular resemblance to the anomalous profile of the X1 in the Boulder clone, in which the X1 has undergone a structural reorganisation. The autoradiographic profile of the P196 CD chromosome does, however, show a much closer resemblance to that of the corresponding chromosome in the Boulder clone than to those of the CD196 in the other four virgo clones studied. These investigations confirm the considerable evolutionary stability of DNA replication patterns.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00285950
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  • 8
    Digitale Medien
    Digitale Medien
    Cytogenetics of the parthenogenetic grasshopper Warramaba virgo and its bisexual relatives (1983)
    Springer
    Chromosoma 88 (1983), S. 227-236 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Combinations of DNA-binding fluorescent dyes and counterstains that enhance selectivity and contrast in primary stain fluorescence were used to differentiate types of C-bands in the genus Warramaba. Chromomycin A3 (in conjunction with two A-T binding counterstains), which identifies chromosome segments enriched in G-C base pair clusters, stains only a minority of the C-bands in Warramaba species, but these include all those known to contain 18S + 26S rRNA cistrons and most of those containing 5S rRNA genes. DAPI/actinomycin D fluorescent staining is positive for a very few bands, including two (in the Standard phylad of W. virgo) that are at or adjacent to sites containing 5S rRNA cistrons. One of the latter regions is also positively stained by DAPI/distamycin A which, in addition, highlights some centromeric bands. The fluorescent staining patterns of the Standard and Boulder-Zanthus phylads of W. virgo are significantly different, confirming their independent origin by hybridization between different races of the ancestral species “P169” and “P196”.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00285625
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  • 9
    Digitale Medien
    Digitale Medien
    Biased gene conversion and asymmetrical introgression between subspecies (1988)
    Springer
    Chromosoma 96 (1988), S. 368-371 
    Details
    ISSN: 1432-0886
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Data from chromosomal in situ hybridization and restriction fragment length polymorphism (RFLP) of ribosomal DNA (rDNA) obtained from the same individuals of two subspecies of the Australian grasshopper Caledia captiva, suggest the occurrence of biased exchange of DNA sequences in hybrid individuals. Thus, there are a disproportionate number of Torresian individuals that possess Moreton ribosomal RNA gene sequences. This bias correlates with the previously described pattern of asymmetrical introgression of Moreton rDNA into Torresian populations. The present findings demonstrate the potential effect of biased gene conversion on the frequencies of introduced gene variants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00330703
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  • 10
    Digitale Medien
    Digitale Medien
    Variation within and between nucleolar organizer regions in Australian hylid frogs (Anura) shown by 18S+28S in-situ hybridization (1990)
    Springer
    Genetica 80 (1990), S. 17-29 
    Details
    ISSN: 1573-6857
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Five distinct classes of secondary constriction are found in the hylid frogs from the genera Litoria and Cyclorana, each of which is defined by its C-banding pattern and morphology (King, 1980, 1987). In-situ hybridization experiments utilizing 18S+28S copy RNA probes derived from Xenopus and Drosophila rDNA templates, were made on nine species of frogs possessing the major constriction types. Types 1, 2, 4, and 5 are confirmed as being NORs. These results also indicate that type 1 and 2 constriction types are not differentially despiralized as previously suggested, but show absolute differences in the quantity of ribosomal DNA present. This variation took two forms, deletion polymorphism and amplification polymorphism. These differences were observed between homologues within cells and between cells within individuals. Animals possessing these ‘despiralized’ constrictions are therefore mosaics for both deletion and amplification polymorphisms. Polymorphism frequencies vary greatly between constriction types. Some specimens have a higher level of presence/absence heterozygosity, (L. moorei, type 2, L. nannotis type 5, L. raniformis) (animal A, pair 8 type 2), than do others (L. peronii, L. rothii, L. caerulea). The above species also vary markedly in the degree and frequency of amplification of the NORs. The type 4 constrictions analysed (L. coplandi, L. Lesueuri and C. novaehollandiae) have a particularly low frequency of presence/absence heterozygosity, and they have fewer size heteromorphisms between homologues. The type 3 ephemeral constrictions did not hybridize to cRNA probes at any stage. In all but one of the species studied, a single pair of chromosomes possessed an NOR. However, in L. raniformis these occurred on two pairs of chromosomes. Each of these sites behaved independently, and the pair 8 constriction had significantly more between cell variation than did that on pair 13. The significance of these observations is discussed and is related to the evolution of NOR structure and the distribution of heterochromatin in amphibians.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00120116
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