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Karyotype evolution of African clades of theraphosid mygalomorphs
Košátko, Prokop ; Král, Jiří (advisor) ; Nguyen, Petr (referee)
Karyotypes of mygalomorph spiders are not satisfactorily known. This thesis is focused on the basic cytogenetic analysis of selected species of African clades of theraphosid mygalomorphs. It includes four subfamilies: Eumenophorinae, Harpactirinae, Ischnocolinae and Stromatopelminae. Diploid numbers, chromosome morphology, sex chromosome systems and chromosome behaviour in male germline in the selected species of African theraphosid subfamilies were studied. The findings support published results, that refer of high karyotype diversity in Theraphosidae. Diploid chromosome number reduction is probably a basic trend of theraphosid karyotype evolution. The majority of analysed species exhibited one, two or three sex chromosomes. In some species neo-sex chromosome systems were found. In some species one or two sex chromosome pairs (SCP), composed of chromosomes which lack morphological differentiation were detected. Nucleolus organizer regions were detected by fluorescent in situ hybridization in several species. Constitutive heterochromatin detection was performed by C-banding in two species. Keywords: constitutive heterochromatin, diploid number, karyotype, fluorescence in situ hybridization, Mygalomorphae, nucleolus organizer region, SCP, sex chromosome, spider, Theraphosidae
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Karyotype analysis of selected groups of tetrapulmonate arachnids
Reyes Lerma, Azucena Claudia ; Sember, Alexandr (advisor) ; Johnson Pokorná, Martina (referee) ; de Bello Cioffi, Marcelo (referee)
Arachnids are a highly speciose group of arthropods with about 130 000 extant species from 12 orders. Some arachnid species are of economic and medical interest. They also offer various opportunities to study the link between genome and karyotype variability and morphological and ecological diversification, evolution and adaptation. The knowledge about arachnid karyotypes and genomes is, however, still limited. The available data show wide range of diploid chromosome numbers (2n), monocentric or holocentric chromosomal structure, variability in sex chromosome systems (especially in spiders) and modifications of meiosis. The main objective of this doctoral thesis was to study by conventional and molecular cytogenetic methods the mechanisms of karyotype evolution in haplogyne spiders (with monocentric and holocentric chromosomes), and further in two families (Charinidae and Phrynidae) from the closely related order Amblypygi. The selected groups offer unique insights into fundamental karyotype traits of the arachnid clade Tetrapulmonata, and they also enable to analyse the role of polyploidy in arachnid karyotype evolution and the evolutionary mechanisms behind the emergence of holocentric chromosomes. Our data suggest that holocentric chromosomes are an autoapomorphy for the haplogyne superfamily...
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Karyotype analysis of mesothelid spiders
Prokopcová, Lenka ; Král, Jiří (advisor) ; Zrzavá, Magda (referee)
Cytogenetics of mesothelid spiders is largely unkown. The presented diploma thesis is focused on the karyotype evolution of these spiders. As it is the most basal group of spiders, the analysis of its cytogenetics can bring important data about ancestral spider karyotype. In the framework of my thesis, I analysed diploid chromosome numbers, chromosome morphology, meiotic division, sex chromosomes and the pattern of selected molecular markers that were detected by fluorescence in situ hybridization. According to my results, mesothelid spiders have a high number of chromosomes and the prevalence of monoarmed chromosomes. Unlike other spiders, mesothelids have little differentiated sex chromosomes. Key words: evolution, spider, chromosome, karyotype, fluorescence in situ hybridization, nucleolar organiser region, sex chromosomes
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Karyotype evolution of African clades of theraphosid mygalomorphs
Košátko, Prokop ; Král, Jiří (advisor) ; Nguyen, Petr (referee)
Karyotypes of mygalomorph spiders are not satisfactorily known. This thesis is focused on the basic cytogenetic analysis of selected species of African clades of theraphosid mygalomorphs. It includes four subfamilies: Eumenophorinae, Harpactirinae, Ischnocolinae and Stromatopelminae. Diploid numbers, chromosome morphology, sex chromosome systems and chromosome behaviour in male germline in the selected species of African theraphosid subfamilies were studied. The findings support published results, that refer of high karyotype diversity in Theraphosidae. Diploid chromosome number reduction is probably a basic trend of theraphosid karyotype evolution. The majority of analysed species exhibited one, two or three sex chromosomes. In some species neo-sex chromosome systems were found. In some species one or two sex chromosome pairs (SCP), composed of chromosomes which lack morphological differentiation were detected. Nucleolus organizer regions were detected by fluorescent in situ hybridization in several species. Constitutive heterochromatin detection was performed by C-banding in two species. Keywords: constitutive heterochromatin, diploid number, karyotype, fluorescence in situ hybridization, Mygalomorphae, nucleolus organizer region, SCP, sex chromosome, spider, Theraphosidae
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Analysis of sex chromosomes and gene clusters in selected mygalomorph and araneomorph spiders
Pappová, Michaela ; Král, Jiří (advisor) ; Johnson Pokorná, Martina (referee)
1 Abstract: The diploma thesis focuses on study of sex chromosomes evolution and repetitive organized genes of chosen mygalomorph and araneomorph spiders. Spiders are characterized by complexicity of sex chromosome systems, their karyotypes contain multiple sex chromosomes X. Besides multiple X chromosomes they also contain a pair or two pairs of nondiferentiated sex chromosomes X and Y. The used methods include methods of classical cytogenetics (preparation of chromosome slides, C-banding) and methods of molecular cytogenetics (fluorescent in situ hybridization and comparative genome hybridization). Complex sex systems were discovered in the studied Theraphosidae spiders. In Theraphosidae spiders Atropothele socotrana and Poecilotheria vittata neo-sex chromosomes were found. Analysis of molecular differentiation of sex chromosomes suggests low differentiation of Y chromosome in neo-sex chromosomes and pair of nondifferentiated sex chromosomes XY. In haplogyne spider Kukulcania aff. hibernalis (X1X2Y), the Y chromosome was significantly differentiated, male specific signal covered the whole chromosome. Detection of 18S rDNA showed that karyotypes of majority of analysed Theraphosidae spiders and haplogyne spiders contain low number (1 or 2) of nucleolar organizing regions localized terminally, which...
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Karyotype analysis of mesothelid spiders
Prokopcová, Lenka ; Král, Jiří (advisor) ; Zrzavá, Magda (referee)
Cytogenetics of mesothelid spiders is largely unkown. The presented diploma thesis is focused on the karyotype evolution of these spiders. As it is the most basal group of spiders, the analysis of its cytogenetics can bring important data about ancestral spider karyotype. In the framework of my thesis, I analysed diploid chromosome numbers, chromosome morphology, meiotic division, sex chromosomes and the pattern of selected molecular markers that were detected by fluorescence in situ hybridization. According to my results, mesothelid spiders have a high number of chromosomes and the prevalence of monoarmed chromosomes. Unlike other spiders, mesothelids have little differentiated sex chromosomes. Key words: evolution, spider, chromosome, karyotype, fluorescence in situ hybridization, nucleolar organiser region, sex chromosomes
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Molecular composition of constitutive heterochromatin
Pajpach, Filip ; Král, Jiří (advisor) ; Holá, Dana (referee)
Constitutive heterochromatin of eukaryotes includes various types of repetitive DNA and transposons characteristic for given region. DNA of centromeric and telomeric re- gions is usually highly methylated and transcribed to RNA transcripts, which participate in formation, functions and spreading of heterochromatin along with histones, their mod- ifications and non-histone proteins. The most typical histone modification in heterochro- matin is methylation, which forms the binding site for protein HP1. This protein (and his paralogues in other eukaryotes except for S. cerevisiae) participates in formation of com- plexes including other proteins like histone methylases SUV39H and their paralogues. Es- sential are also telosome proteins regulating telomeric heterochromatin, Polycomb group proteins and many others, for instance MBD1, Epe1, SUMO and DNA methylases DNMT. Many proteins form complexes, which partake in mechanisms necessary for heterochro- matin maintenance, for example RDRC and RITS complexes in RNA interference, SHREC complex in heterochromatin spreading, and PRC complexes forming heterochromatin in specific situations. Key words: centromere, DNA, histone, HP1, constitutive heterochromatin, methylation, modification, protein, RNA, specific, telomere
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