|
|
Karyotype differentiation of the harvestmen belonging to the subroder Laniatores from South Africa
Marešová, Alexandra ; Šťáhlavský, František (advisor) ; Symonová, Radka (referee)
Current cytogenetic knowledge of the suborder Laniatores is only known for 11 species from South and North America. This study presents the first cytogenetic analyses of South African families Biantidae and Triaenonychidae which belong to the most diverse suborder of harvestmen. After analyzing the karyotype, variability in the diploid chromosome number was found, with Biantidae having 2n = 38-52 and Triaenonychidae having 2n = 28-64. Variability was also observed in the morphology of chromosomes. While both families predominantly exhibit bi-armed chromosomes, individual species show different representations of various morphological types. In addition to basic cytogenetic analyses, fluorescent in situ hybridization (FISH) was performed, revealing variability in the number and location of gene clusters for 18S rRNA. Using this method, the telomeric motif (TTAGG)n was also localized, which was present only at the ends of chromosomes in all analyzed species from both families. Key words: cytogenetics, harvestmen, Laniatores, FISH, 18S rRNA, karyotype variability
|
|
|
Sex chromosome evolution in selected taxa of teleost fishes (Teleostei)
Pavlica, Tomáš ; Sember, Alexandr (advisor) ; Kratochvíl, Lukáš (referee)
Teleosts represent more than half of the extant vertebrate species. They show a wide range of mechanisms driving both sex determination and sex differentiation, including nine sex chromosome systems described to date. Teleost sex chromosomes are generally considered as evolutionarily young, therefore they are suitable for an analysis of the early stages of evolution of these unique genomic regions. The aim of the current thesis was to analyze the presence and degree of differentiation of sex chromosomes in two Nothobranchius killifish species and one Bunocephalus banjo catfish representative using conventional and molecular cytogenetic methods. Different populations of N. kadleci and N. furzeri analysed in this thesis shared anXY sex chromosome system. Despite the obvious heteromorphy of their sex chromosomes, comparative genome hybridization (CGH) did not show any region of differentiation. Analysis of synaptonemal complexes by immunostaining coupled with the mapping of 18S rDNA and telomeric repeats using fluorescent in situ hybridization (FISH) showed mainly standard pairing with the contribution of synaptic adjustment. Pachytene spreads of females from one N. furzeri population contained a small supernumerary chromosome which was not present in metaphases of studied somatic cells. Distribution...
|
guest ::
