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Charakterizace oocytů afrických rypošů
KOPECKÁ, Eva
This study is focused on characterisation of oocytes of long-lived rodents, naked mole-rat and giant mole-rat, that are emerging models of long-term oocyte and ovarian quality. In the second part, the effect of repeated ovulations on aging-associated quality decline of oocyte is studied, comparing mouse and giant mole-rat.
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Evolution of karyotype and sex chromosomes in African and American clades of theraphosid mygalomorph spiders
Turečková, Eva ; Forman, Martin (advisor) ; Šťáhlavský, František (referee)
The family Theraphosidae (tarantulas) are generally known of spiders, often keept as hobby pets. Despite their popularity, many aspect of tarantula biology are still omitted. This include also cytogenetic research. In order, to fill this gap I analysed chromosomal constitution in 13 species of tarantulas belonging to the different genera from Africa and south/central America. Data set in this thesis included, also, the tarantula with so far the best covered genome Acanthoscuria genicullata, and the iconic, giant spider Theraphosa stirmi. Conventional giemsa staining of male meiotic plates was accompanied with visualisation of major rRNA clusters using fluorescence in situ hybridization with 18S rDNA probe. Diploid counts ranges considerably from 31 (Ceratogyrus meridionalis) to 83 (Theraphosa stirmi). In some specimens presence of multivalents indicated a possibility of hybridization of different chromosomal races in a hobby lineages. Various types of differentiated sex chromosomes have been proven, including X0, X1X20 X1X2X30 systems. Interestingly, the diversity in karyotype features was not linked with diversity in major rDNA cluster number. Most of the species displayed one prominent locus located on autosomes. Two species exhibited polymorphism in the presence of one more additive smaller...
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Genes of early meiotic prophase I of spermatogenesis in house mouse
Škaloudová, Eliška ; Trachtulec, Zdeněk (advisor) ; Forman, Martin (referee)
Meiosis is an essential cellular process that is necessary for gamete formation in all sexually reproducing organisms. This work is focused on the description of the genes of early stages of meiotic division in males of a mammalian model, the house mouse. The first part summarizes meiosis focusing on prophase I, which is longer than prophase II. Prophase I is divided into five stages, namely leptotene, zygotene, pachytene, diplotene, and diakinesis. Mouse spermatogenesis and its differences from oogenesis are also briefly described. The second part provides a list of genes encoding proteins required for initiation of meiotic division, pairing and synapses of chromosomes, and initiation of the catalysis of double-strand breaks. Double-strand breaks are repaired by homologous recombination, which may result in so-called crossing-over, the major source of genetic variability. The work deals with the early stage of homologous recombination and components required for this process. Localization of meiotic double-strand breaks in the genome is not random and is under the control of the Prdm9 gene, which seems to take multiple roles, such as the formation of new subspecies of the house mouse. Knowledge of the genes controlling the early stages of meiotic division is a prerequisite to understanding some of...
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Genetic interactions of the Prdm9 gene
Šebestová, Lenka ; Trachtulec, Zdeněk (advisor) ; Král, Jiří (referee)
The Prdm9 gene (PR domain containing 9, Meisetz, Hybrid sterility 1) encodes enzyme that trimethylates histone 3 on lysines 4 and 36. These methylation marks determine the positions of DNA double-strand breaks that are repaired by meiotic homologous recombination. In this study, we assayed genetic interactions of Prdm9 with two genes important for spermatogenesis - Mili (Piwil2) involved in piRNA biogenesis and Mybl1 encoding transcription factor that regulates many genes important for prophase I, including piRNA precursors. We crossed laboratory mice carrying mutation in Prdm9 with heterozygotes for mutation in Mybl1 or Mili, and created compound heterozygotes and, in case of Mybl1, also double homozygotes. We assessed body weight and male fertility parameters (weight of testes, sperm count, malformed sperm, percentage of tubules containing spermatocytes and of abnormal nuclei of pachytene spermatocytes) of these mice and compared them to controls. We also investigated the effect of Mybl1 and Mili mutations on fecundity of F1 intersubspecific hybrids. Our results revealed possible interactions of Prdm9 and Mybl1 in the laboratory mouse. Decreased gene dosage of Mybl1 reduced fertility of intersubspecific F1 hybrids. Interaction between Prdm9 and Mili in both laboratory mouse and F1 hybrids remain...
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Sex in Trypanosomatids
Kvapilová, Kateřina ; Volf, Petr (advisor) ; Čepička, Ivan (referee)
3 Abstrakt Rody Leishmania a Trypanosoma jsou původci vážných lidských onemocnění: leishmaniózy a trypanosomózy. Dlouhá léta nebyly u těchto parazitů nalezeny přesvědčivé důkazy o genetické výměně, a proto byly rody Trypanosoma a Leishmania považovány za klonálně se rozmnožující, a to binárním štěpením jako většina prvoků. Výzkum ztěžovaly i skutečnosti, že pohlavní dimorfismus není patrný a chromosomy nekondenzují, tudíž nejsou viditelné. Nicméně klonální model začaly zpochybňovat pozorování přirozeně se vyskytujících hybridních druhů. Nejdříve byla existence sexu popsána u trypanosom a to prvním přímým důkazem hybridů T. brucei, získaných po společném přenosu rodičů mouchou tsetse. U leishmanii byl důkaz poskytnut na základě dvojitě rezistentních hybridů a sexuální výměna podstupovala stejný meiotický proces jako T. brucei. Byli pozorovaní přirozeně se vyskytující hybridi Nového i Starého světa jak u rodu Viannia, tak i u rodu Leishmania. Otázkou dalších výzkumů bylo, jaký je mechanismus genetické výměny, ale odpověď dodnes není jasná. Klíčová slova: genetická výměna, Trypanosoma, Leishmania, klonalita, meióza, GFP, přenašeč Abstract Genera Leishmania and Trypanosoma are agents of serious human diseases: leishmaniasis and trypanosomózy. For many years these parasites were considered clone-replicating by...
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Analysis of chromosomal aberrations in sperm by fluorescence in situ hybridization
Bendová, Petra ; Diblík, Jan (advisor) ; Novotná, Drahuše (referee)
The presented bachelor work is focused on the determination of frequency chromosomally abnormal sperm in the semen of healthy men (donors) with normal karyotype (46, XY). The important process, which plays an irreplaceable role in the development of numerical aberrations of chromosomes or structural abnormalities in the segregation of the gametes, is meiosis. Therefore, I devote much attention on meiosis in the theoretical part. The theoretical part is focused on the process of pre mature sperm (spermatogenesis), and the consequences of fertilize the oocyte by aneuploid sperm. In my work I present an overview of numerical abnormalities in autosomes and gonosomes and their frequency and distribution of gametes in healthy men. I also focused on the distribution and a brief description of structural aberrations affecting chromosomes and not least I paid attention on method of multicolor interphase fluorescence in situ hybridization, which in combination with sperm chromatin dekondenzation become irreplaceable and valuable research tool for rapid analysis of chromosomal abnormalities in large sperm samples. The experimental part of bachelor work deals with monitoring the frequency of selected numerical abnormalities in sperm samples of five donors aged 23 to 30 years with the use of I-FISH (fluorescence in situ...
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Earlier evolutionary dead-ends, now the creators of a reproductive strategy: the origin and reproduction of the all-male water frog lineage Pelophylax esculentus
Doležálková, Marie ; Choleva, Lukáš (advisor) ; Mikulíček, Peter (referee) ; Kratochvíl, Lukáš (referee)
Asexual modes of reproduction are usually based on the principle of copying (cloning) DNA from the female and passing it on to the offspring. For most asexually reproducing vertebrates the progeny develop from an unreduced and often unfertilised egg. This is driven by the mechanisms of parthenogenetic and gynogenetic reproduction. While in the former the clonal germ cell develops spontaneously and separately, in the latter a sexual partner is needed to activate the cleavage of the ovum, although without the fusion of the sperm and egg. Therefore in both cases there is no fertilization and the clonal progeny consist solely of daughters, hence the majority of previous studies have only focused on asexual female lineages. However, on rare occasions asexual clonal males can arise when the right fertilization occurs. Whilst these offspring are usually infertile, fertile diploid asexual males have been discovered in just three genera of hybrid origin in vertebrates. One of these unique cases is the European water frog complex of the genus Pelophylax, whose distribution includes the Czech Republic. In areas around the upper Odra River populations of hybrid males were recently discovered who form stable all-male lineages, similar to those formed by asexual females. The results of this study show that males produce...
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Polyploidy with specific view to paleopolyploidy and its detection
Kotz, Matěj ; Král, Jiří (advisor) ; Rothová, Olga (referee)
Polyploidy is a significant phenomenon in the evolution of eucaryotic organisms. It has been a subject of interest of biologists for decades and it has been studied particularly largely in plants, where it most often occurs. This thesis handles occurrence of poylploidy in organims and a special emphasis is laid on old polyploidization events occurrence of polyploidy in animal taxa. Furthermore, the types of polyploidy and obstacles are discussed here, that a polyploid organism has to tackle to stabilize its genome. That also includes the need to ensure the correct chromosome segregation in a meiotic division. A special case of polyploidy is paleopolyploidy (sometimes refered to as "ancient polyploidy" in English), which is an evolutionary old polyploidization event, that is followed by the process of diploidization. This process is characterized besides others by a large number of structural changes in chromosomes and a loss of some DNA sequences and a gradual transition of the polyploid genome to the cytologically diploid state. Because of these changes, it is difficult to detect a paleopolyploidy and the main part of this thesis is dedicated to this problem, in which the main approaches that might lead to its detection are discussed. Key words: polyploidy, animal, plant, meiosis, paleopolyploidy,...
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The role of cohesin genes in the meiosis of male house mouse
Šebestová, Lenka ; Trachtulec, Zdeněk (advisor) ; Král, Jiří (referee)
Cohesin genes play an important role in cell division. They ensure proper chromosome segregation during mitosis and meiosis. This study is focused on the role of cohesin genes during meiosis in male house mouse (Mus musculus). At first, this study introduces key processes of mammalian meiosis. Next, the structure of cohesin complex is described; it consists of a heterodimer SMC proteins - SMC3 and SMC1α or SMC1β, which are enclosed to the ring by cleavable subunit RAD21, RAD21L or REC8. Fourth subunit - a STAG protein (STAG1, STAG2 or STAG3) associates with the cleavable subunit. Meiotic function of specific cohesin proteins (SMC1β, RAD21L, REC8 and STAG3) as deduced from the phenotypes of the deficiencies of their genes in male mouse is depicted. All these four genes are necessary for many processes during meiosis, - e.q. sister chromatid cohesion maintenance, synapsis and recombination. STAG3, SMC1β, and REC8 are necessary for centromeric cohesion. STAG3 and RAD21L are important for the assembly of the remaining cohesin subunits. The most important phenotype of deficiency of all four genes is the complete meiotic arrest in male prophase I. Therefore, cohesin research is important for the investigation of the causes of sterility in mammals. key words: cohesin, meiosis, spermatogenesis, mouse,...
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Karyotype analysis of selected representatives of two pedipalpid orders, Amblypygi and Uropygi
Sember, Alexandr ; Král, Jiří (advisor) ; Ráb, Petr (referee)
Karyotype analysis of selected species from arachnid orders Amblypygi and Uropygi Whip spiders (Amblypygi) and whip scorpions (Uropygi) represent relict arachnid orders which has been found already at Upper Carboniferous strata. Although cytogenetic data from amblypygids and uropygids might be important to reconstruct karyotype evolution of arachnids, cytogenetics of these orders is almost unknown. Presented study is aimed in analysis of karyotype and meiosis in 16 species of Amblypygi and 4 species of Uropygi. Both groups are characterized by considerable range of diploid chromosome numbers (2n = 24 - 86 in Amblypygi and 36 - 66 in Uropygi). Analysed species does not exhibit morfologically differentiated sex chromosomes. Differentiation of sex chromosomes on molecular level was revealed in amblypygid Paraphrynus mexicanus by comparative genome hybridization. Obtained data indicate XY/XX sex chromosome system in this species. Comparison of karyotype data indicates reduction of chromosome numbers during evolution of both orders. In Amblypygi, this reduction was accompanied by increase of number of biarmed chromosomes. This trend is not apparent in Uropygi. Karyotypes of most analysed amblypygids and uropygids are also characterized by low amount of heterochromatin. Most studied species exhibit two pairs...
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