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  • 1
    Electronic Resource
    Electronic Resource
    Cytogenetics and taxonomy: considerations based on chromosome studies of freshwater fish (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 28 (1986), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Several species belonging to different families of Brazilian freshwater fish are being studied cytogenetically, and the results obtained thus far have indicated interesting peculiarities. We show that karyotypic analysis, in addition to contributing to a better knowledge of the species, can also aid in their characterization, and we demonstrate the advantages of an associated cytogenetic-taxonomic study, especially with respect to some groups of neotropical freshwater fish in Brazil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1986.tb05153.x
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  • 2
    Electronic Resource
    Electronic Resource
    PCR primed with minisatellite core sequences yields species-specific patterns and assessment of population variability in fishes of the genus Brycon (2003)
    Berlin, Germany : Blackwell Verlag GmbH
    Journal of applied ichthyology 19 (2003), S. 0 
    Details
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Minisatellite core sequences were used as single primers in polymerase chain reaction (PCR) to amplify genomic DNA in a way similar to the random amplified polymorphic DNA methodology. This technique, known as Directed Amplification of Minisatellite-region DNA, was applied in order to differentiate three neotropical fish species (Brycon orbignyanus, B. microlepis and B. lundii) and to detect possible genetic variations among samples of the threatened species, B. lundii, collected in two regions with distinct environmental conditions in the area of influence of a hydroelectric dam. Most primers generated species-specific banding patterns and high levels of intraspecific polymorphism. The genetic variation observed between the two sampling regions of B. lundii was also high enough to suggest the presence of distinct stocks of this species along the same river basin. The results demonstrated that minisatellite core sequences are potentially useful as single primers in PCR to assist in species and population identification. The observed genetic stock differentiation in B. lundii associated with ecological and demographic data constitute a crucial task to develop efficient conservation strategies in order to preserve the genetic diversity of this endangered fish species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0426.2003.00443.x
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  • 3
    Electronic Resource
    Electronic Resource
    Cytogenetics of the genus Leporinus (Pisces, Anostomidae). 1.Karyotype analysis, heterochromatin distribution and sex chromosomes (1997)
    Springer
    Chromosome research 5 (1997), S. 12-22 
    Details
    ISSN: 1573-6849
    Keywords: fish cytogenetics ; heterochromatin ; karyo-type evolution Leporinus ; sex chromosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytogenetic analyses (Giemsa staining, C-banding, AgNO3 labelling of nucleolus organizer regions (NORs) and staining with base-specific fluorochromes) were performed on the South American fish species Leporinus friderici, L. obtusidens and L. elongatus. The overall karyotypic structure, position of NORs, as well as the amount,distribution and composition of constitutive heterochromatin were determined. Particular attention was given to the highly differentiated ZZ/ZW sex chromosome system of L. obtusidens and L. elongatus. Sharing the apparently ancient macroscopic karyotype of Anostomidae, all three species have 2n=54 meta- or submetacentric chromosomes. NORs were found exclusively on chromosome pair 2, which may represent the ancestral NOR-bearing chromosome of the anostomid karyotype. Observed differences in the relative position of NORs along chromosome 2 and variations in the amount and distribution of constitutive heterochromatin throughout the karyotype were most probably caused by heterochromatin-mediated chromosome rearrangements. Detailed analysis of the morphologically similar heteromorphic ZZ/ZW sex chromosomes of L. obtusidens and L. elongatus allowed detection of differences in the DNA composition of the largely heterochromatic W chromosomes. However, since these and the W chromosomes of three other Leporinus species exhibit homologies with respect to their relative size, centromere position and amount and distribution of heterochromatin, it is concluded that they evolved from the same ancestral W chromosome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018485217391
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  • 4
    Electronic Resource
    Electronic Resource
    An overview of marine fish cytogenetics (2000)
    Springer
    Hydrobiologia 420 (2000), S. 55-62 
    Details
    ISSN: 1573-5117
    Keywords: chromosomes ; evolution ; nucleolar organizer region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The number of cytogenetic studies of marine fish has increased in recent years. Fish groups, such as Perciformes, which comprises many of the extant marine teleosts of economic importance, show little divergence in chromosome number and most species display a diploid number of 48 acrocentric chromosomes. In the Serranidae, Sparidae, Sciaenidae (Perciformes) and Mugilidae (Mugiliformes) small chromosome variations are restricted to subtle heterochromatin or nucleolar organizer region (NOR) modifications. There appears to exist a strict relationship between both absence of geographic barriers throughout the marine environment and high mobility of these animals (eggs, larvae, or adults), with a rarity of chromosome rearrangement at the macrostructural level. Moreover, a cellular homeostasis might also be important to karyotype maintenance among these fishes, limiting changes in the chromosome complement to cryptic chromosome rearrangements. Other groups, such as Blenniidae, Gobiidae and Scorpaenidae, for instance, show more extensive chromosome diversity, which is probably related to limited mobility. Numerical and structural chromosome polymorphisms and several sexual chromosome systems are recurrent among these fishes. A wide karyotypic diversification also characterizes the Tetraodontiformes, an interesting fish group with peculiar morphological, physiological and ecological characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003977418900
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    Paper (German National Licenses)
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