Global ETD Search

11	Morphological variation and genetic diversity of Triops cancriformis (Crustacea: Notostraca) and their potential for understanding the influence of postglacial distribution and habitat fragmentation Zierold, Thorid 06 July 2006 (has links) Triops cancriformis (Crustacea: Notostraca) occurs in ephemeral habitats like rain pools or floodplain pools distributed over a large geographical range. The named habitats are disturbed by human impacts and, consequently, T. cancriformis is endangered throughout its distribution range. In the present thesis the populated habitats and threats are characterised and further morphological and genetic variations detected among and within European populations are reported. On the basis of recent investigations it is shown that T. cancriformis subspecies separation is hampered by an individual variability which points to the necessity of species revision. The analysis of mitochondrial gene sequence data suggests that the species has colonised most of Europe very recently. The advantage of a complex reproductive strategy in T. cancriformis in this process is discussed. The population structure resolved with nuclear DNA markers highlights that there is low allelic diversity among and within populations compared to other Branchiopoda (Daphnia). By means of the present study it can be shown that habitat conservation is most important to protect T. cancriformis. info:eu-repo/classification/ddc/590 ddc:590
12	Yeast mitochondrial copper metabolism: topology and role of Cox11p Khalimonchuk, Oleh 15 February 2006 (has links) Cytochrome c oxidase (COX) is one of two known Cu-containing enzymes in mitochondria. Delivery and insertion of copper into COX are very complex processes that require multiple steps and involve a large number of assisting factors. One of the involved components is Cox11p, a copper binding protein in the inner mitochondrial membrane that is conserved from prokaryotes to eukaryotes. Cox11p is essential for respiratory growth and implicated in the assembly of the CuB site located in subunit Cox1p of COX. In the thesis the topology of Cox11p was determined and evidence for its association with the mitochondrial translation machinery is provided. The interaction of Cox11p with mitoribosomes is mediated by its single evolutionary conserved transmembrane segment and appears to be indirect and mediated by another conserved membrane protein(s). A model is proposed in which the CuB site is co-translationally formed by a transient interaction between Cox11p and the nascent Cox1p in the mitochondrial intermembrane space. In addition the genetic and biochemical characterization of S. pombe Cox11p homologue was performed. Two versions of cox11+ gene are detected in a haploid S. pombe genome. Cells lacking either of the cox11+ copies remain respiratory competent, whereas deletion of both S. pombe cox11+ alleles appears to result in either spore lethality or in severe decrease of spores viability. Thus, both versions of SpCox11p are functional and important. In S. pombe Cox11p exists as a tandem with the mitoribosomal protein Rsm22p. This precursor protein is cleaved during mitochondrial import into two mature protein species corresponding to Rsm22p- and Cox11p-like moieties. info:eu-repo/classification/ddc/570 ddc:570
13	Divergent functions of the Arabidopsis mitochondrial SCO proteins: HCC1 is essential for COX activity while HCC2 is involved in the UV-B stress response Steinebrunner, Iris, Gey, Uta, Andres, Manuela, Garcia, Lucila, Gonzalez, Daniel H. 11 July 2014 (has links) (PDF) The two related putative cytochrome c oxidase (COX) assembly factors HCC1 and HCC2 from Arabidopsis thaliana are Homologs of the yeast Copper Chaperones Sco1p and Sco2p. The hcc1 null mutation was previously shown to be embryo lethal while the disruption of the HCC2 gene function had no obvious effect on plant development, but increased the expression of stress-responsive genes. Both HCC1 and HCC2 contain a thioredoxin domain, but only HCC1 carries a Cu-binding motif also found in Sco1p and Sco2p. In order to investigate the physiological implications suggested by this difference, various hcc1 and hcc2 mutants were generated and analyzed. The lethality of the hcc1 knockout mutation was rescued by complementation with the HCC1 gene under the control of the embryo-specific promoter ABSCISIC ACID INSENSITIVE 3. However, the complemented seedlings did not grow into mature plants, underscoring the general importance of HCC1 for plant growth. The HCC2 homolog was shown to localize to mitochondria like HCC1, yet the function of HCC2 is evidently different, because two hcc2 knockout lines developed normally and exhibited only mild growth suppression compared with the wild type (WT). However, hcc2 knockouts were more sensitive to UV-B treatment than the WT. Complementation of the hcc2 knockout with HCC2 rescued the UV-B-sensitive phenotype. In agreement with this, exposure of wild-type plants to UV-B led to an increase of HCC2 transcripts. In order to corroborate a function of HCC1 and HCC2 in COX biogenesis, COX activity of hcc1 and hcc2 mutants was compared. While the loss of HCC2 function had no significant effect on COX activity, the disruption of one HCC1 gene copy was enough to suppress respiration by more than half compared with the WT. Therefore, we conclude that HCC1 is essential for COX function, most likely by delivering Cu to the catalytic center. HCC2, on the other hand, seems to be involved directly or indirectly in UV-B-stress responses. SCO Synthese Cytochrom-c-Oxidase Mitochondrien Kupferchaperon COX-Komplex UV-B Stress Pflanzenwachstum Pflanzenentwicklung BN-PAGE Arabidopsis thaliana TU Dresden Publikationsfonds SCO (synthesis of cytochrome c oxidase) mitochondria copper chaperone COX complex UV-B stress plant growth and development BN-PAGE Arabidopsis thaliana Technical University Dresden Publication funds ddc:570 rvk:WA 15000
14	Divergent functions of the Arabidopsis mitochondrial SCO proteins: HCC1 is essential for COX activity while HCC2 is involved in the UV-B stress response Steinebrunner, Iris, Gey, Uta, Andres, Manuela, Garcia, Lucila, Gonzalez, Daniel H. 11 July 2014 (has links) The two related putative cytochrome c oxidase (COX) assembly factors HCC1 and HCC2 from Arabidopsis thaliana are Homologs of the yeast Copper Chaperones Sco1p and Sco2p. The hcc1 null mutation was previously shown to be embryo lethal while the disruption of the HCC2 gene function had no obvious effect on plant development, but increased the expression of stress-responsive genes. Both HCC1 and HCC2 contain a thioredoxin domain, but only HCC1 carries a Cu-binding motif also found in Sco1p and Sco2p. In order to investigate the physiological implications suggested by this difference, various hcc1 and hcc2 mutants were generated and analyzed. The lethality of the hcc1 knockout mutation was rescued by complementation with the HCC1 gene under the control of the embryo-specific promoter ABSCISIC ACID INSENSITIVE 3. However, the complemented seedlings did not grow into mature plants, underscoring the general importance of HCC1 for plant growth. The HCC2 homolog was shown to localize to mitochondria like HCC1, yet the function of HCC2 is evidently different, because two hcc2 knockout lines developed normally and exhibited only mild growth suppression compared with the wild type (WT). However, hcc2 knockouts were more sensitive to UV-B treatment than the WT. Complementation of the hcc2 knockout with HCC2 rescued the UV-B-sensitive phenotype. In agreement with this, exposure of wild-type plants to UV-B led to an increase of HCC2 transcripts. In order to corroborate a function of HCC1 and HCC2 in COX biogenesis, COX activity of hcc1 and hcc2 mutants was compared. While the loss of HCC2 function had no significant effect on COX activity, the disruption of one HCC1 gene copy was enough to suppress respiration by more than half compared with the WT. Therefore, we conclude that HCC1 is essential for COX function, most likely by delivering Cu to the catalytic center. HCC2, on the other hand, seems to be involved directly or indirectly in UV-B-stress responses. info:eu-repo/classification/ddc/570 ddc:570

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