Cytogenetic analysis and description of the sexual chromosome determination system ZZ/ZW of species of the fish genus Serrapinnus (Characidae, Cheirodontinae)

Four populations of Serrapinnus notomelas and one population of Serrapinnus sp.1, both belonging to the subfamily Cheirodontinae, were analyzed by Giemsa and silver nitrate impregnation techniques. We found 2n = 52 chromosomes for all populations, with interspecific differences in the karyotype formula; S. notomelas showed 16m + 22sm + 10st + 4a, with fundamental number (FN) = 100 for males, and 16m + 23sm + 10st + 3a, with FN = 101 for females. Serrapinnus sp.1 had 8m + 16sm + 4st + 24a, with FN = 80 for males, and 8m + 15sm + 4st + 25a, with FN = 79 for females. The difference in FN for the two sexes is due to a pair of heteromorphic chromosomes in the females of both species, which characterizes a ZZ/ZW-type mechanism of chromosome sexual determination. Interspecies differences were also found in nucleolus organizer regions (NORs). A simple NOR system was detected in three of four S. notomelas populations, while Serrapinnus sp.1 had two chromosome pairs with NOR. Although S. notomelas and Serrapinnus sp.1 have the same diploid number, differences in the karyotype structure indicate that these are different species. Apparently there was pericentric inversion during the karyotype evolution of these species.

Identificación de cromosomas sexuales marcadores mediante hibridación in situ con fluorescencia (FISH) / Identification of sex chomosome markers using fluorescence in situ hybridization (FISH)

Del 6 al 15 de los casos son síndrome de Turner presentan un cariotipo en mosaico con una línea 45,X, y otra con un pequeño cromosoma sexual marcador de origen no determinado, que puede ser un anillo o un fragmento céntrico. La identificación de su origen, que frecuentemente se dificulta por la falta de resolución de las técnicas citogenéticas y la variabilidad en el fenotipo clínico , es de vital importancia ya que, si provienen de un cromosoma Y, el paciente tiene un riesgo elevado de desarrollar gonadoblastoma. El objetivo del presente trabajo fue determinar el origen de pequeños cromosomas sexuales marcadores mediante la técnica de hibridación in situ con fluorescencia (FISH). Se estudiaron ocho pacientes: siete mostraban fenotipo Turner con genitales externos femeninos, y la octava tenía talla baja con ambigüedad de genitales. En todos los casos se identificó, en el cariotipo de sangre periférica, un mosaico con una línea celular que presentaba un cromosoma sexual marcador; en tres se corroboró el mosaico en fibroblastos. Para la técnica de FISH se utilizaron sondas de DNA marcadas con biotina, con secuencias complementarias a la región centroamérica alfa satélite de los cromosomas X y Y. Con la sonda alfa satélite del X, se estableció que el cromosoma marcador provenía del X en siete pacientes. En la paciente con genitales ambiguos, se determinó que el marcador derivaba del cromosoma Y. Consecuentemenete la técnica FISH fue capaz de identificar el origen de los cromosomas sexuales marcadores en las ocho pacientes

A Karyotype Study in Chiroptera (Bats)

The bat (Chiroptera) is the only mammal that is able to fly as birds do and forms a peculiar taxonomic group in that the diploid number of chromosomes seldom are of the same number in the same genus and the different species in contrast to the other eutherian mammals. At the present time, many karyological problems remain unsolved in Korean bats. It is easy enough to imagine that many interesting things have happened in the chromosomes of the Korean bats as well. The present study was designed in order to get karyotypic data on living species of Korean bats (Vespertilio superans THOMAS and Miniopterus schreibersii fuliginosus (HODGSON). The diploid number of chromosomes of the Vespertilio superans was 38. The autosomes consisted of 6 pairs of the large metacentric, a pair of the small submetacentric and 11 pairs of tile small acrocentric chromosomes. The X chromosome was medium sized and metacentric in type and the Y was a small acrocentric type. The fundamental number was 50. The diploid number of chrmosomes of the Miniopterus schreibersii fuliginosus was 46. The autosomes consisted of 8 pairs of the metacentric type including a pair of minute metacentric chromosomes. and 18 pairs of the small acrocentric type chromosomes. The X chromosome was medium-sized and submetacentric, and the Y was a small acrocentric chromosome. The fundamental number was 52.