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Evolution of telomeric motif in arthropods
Vadovičová, Kristýna ; Forman, Martin (advisor) ; Sadílek, David (referee)
In contrast to other eukaryotes, the telomeres of Arthropoda, the most diversified phylum, are composed of a specific motif (TTAGG)n. The presence of this sequence is conserved within the phylum, yet alternative sequences derived from the ancestral have evolved. Diversity of short motifs has been found especially in the orders Coleoptera, Hymenoptera and Hemiptera. In addition, TRAS and SART retroelements transpose between telomeric sequences in many representatives of different orders. In arthropods, there are still numerous groups whose telomeres do not contain the (TTAGG)n motif, but alternatives have not been proposed yet. One of them is the order Araneae (spiders), as well as some orders of insects.An interesting exception is the order Diptera, where a telomerase-independent telomere elongation mechanism has evolved. The genera Anopheles and Chironomus have telomeres composed of long repeats (up to 350 bp). Drosophila melanogaster relies on a mechanism based on transposition of the telomere-specific retroelements HeT-A, TART and TAHRE. The diversity of telomeric repeats in Diptera can be considerable even in closely related species, which may complicate the identification of novel telomeric sequences in unstudied species. Key words Drosophila, insects, retroelements, telomere, (TTAGG)n
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Endogenous retroviral elements and their functions in the human genome
Famfulíková, Mirka ; Pačes, Jan (advisor) ; Lichá, Irena (referee)
In addition to the coding sequences, the human genome contains a so noncoding DNA, among which we count transposable elements capable of transposition in the genome. The remnants of the past retrovirus infections - endogenous retroviruses (human endogenous retroviruses - HERVs) belong to the transposable elements, which contain the LTR sequences. Human endogenous retroviruses make up to 8% of the size of the human genome. The retroviruses are not only passive relicts, but they have gained some key functions - too. They increase the plasticity of the human genome and some HERV LTRs can serve as binding sites for transcription factors like. Env protein from the families HERV-W and HERV- FRD were coopted by the human genome and are nowadays expressed as proteins Syncitin-1 and Syncitin-2, which are necessary by the forming of human placenta. Unfortunately, the HERV elements can have a negative health impacts. In the last decades they are subject of a debate in connection with various diseases, such as multiple sclerosis, schizophrenia, HIV proliferation and some types of tumorigenesis. The role of HERVs in the human genome is not completely known yet and it is important to continue with their research. Powered by TCPDF (www.tcpdf.org)
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Endogenous retroviral elements and their functions in the human genome
Famfulíková, Mirka ; Pačes, Jan (advisor) ; Lichá, Irena (referee)
In addition to the coding sequences, the human genome contains a so noncoding DNA, among which we count transposable elements capable of transposition in the genome. The remnants of the past retrovirus infections - endogenous retroviruses (human endogenous retroviruses - HERVs) belong to the transposable elements, which contain the LTR sequences. Human endogenous retroviruses make up to 8% of the size of the human genome. The retroviruses are not only passive relicts, but they have gained some key functions - too. They increase the plasticity of the human genome and some HERV LTRs can serve as binding sites for transcription factors like. Env protein from the families HERV-W and HERV- FRD were coopted by the human genome and are nowadays expressed as proteins Syncitin-1 and Syncitin-2, which are necessary by the forming of human placenta. Unfortunately, the HERV elements can have a negative health impacts. In the last decades they are subject of a debate in connection with various diseases, such as multiple sclerosis, schizophrenia, HIV proliferation and some types of tumorigenesis. The role of HERVs in the human genome is not completely known yet and it is important to continue with their research. Powered by TCPDF (www.tcpdf.org)
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