Browsing by Author "Kmita, Hanna"
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Item Applicable Life-History and Molecular Traits for Studying the Effects of Anhydrobiosis on Aging in Tardigrades(Multidisciplinary Digital Publishing Institute (MDPI), 2022-08-17) Nagwani, Amit Kumar; Kaczmarek, Łukasz; Kmita, HannaAnhydrobiosis is induced by loss of water and indicates dehydration tolerance. Survival of dehydration is possible through changes at different levels of organism organization, including a remarkable reduction in metabolic activity at the cellular level. Thus, anhydrobiosis may be regarded as an anti-aging strategy. Accordingly, two hypotheses named after popular stories, “Sleeping Beauty” and “The Picture of Dorian Gray”, were proposed to explain the effect of anhydrobiosis on aging. The two hypotheses predict the presence (The Picture of Dorian Gray) or absence (Sleeping Beauty) of observable aging symptoms for animals undergoing anhydrobiosis. Predictions of these hypotheses have rarely been tested, and the cellular level has not been addressed. Tardigrades appear to be a useful model for studying the effect of anhydrobiosis on aging, as they are able to enter and survive anhydrobiosis at any stage of life, although not with the same success for all species. In this review, we discuss anhydrobiosis and aging mechanisms as well as tardigrade diversity and indicate possible multilevel markers that can be used to study the impact of anhydrobiosis on tardigrade aging. This review provides data on tardigrade diversity that may also be useful for human aging studies.Item Kompleks TOB/SAM: kluczowa rola w biogenezie mitochondriów(2007) Kmita, Hanna; Wojtkowska, MałgorzataBiałka tworzące strukturę beczułki b występują w błonie zewnętrznej bakterii Gramujemnych oraz w błonie zewnętrznej organelli pochodzenia endosymbiotycznego, tj. mitochondriów i chloroplastów, gdzie mogą pełnić różne funkcje. Mitochondrialne białka o strukturze beczułki b biorą udział w imporcie białka, transporcie metabolitów oraz w regulacji morfologii i dystrybucji mitochondriów. Białka te uznaje siê takze za istotny element ewolucji mitochondriów. Mechanizm wbudowywania białek tworzących strukturę beczułki b w błone zewnętrzną mitochondriów i bakterii Gram-ujemnych został niedawno opisany. Co więcej, wykazano, iż uległ on utrwaleniu w toku ewolucji. W przypadku mitochondriów w procesie tym uczestniczy kompleks TOB/SAM (topogeneza białek zewnętrznej błony mitochondrialnej tworzących strukturę beczułki b/maszyneria sortowania i składania białek), tworzony przez trzy podstawowe białka: Tob55 (Sam50), Tob38 (Sam35) and Mas 37 (Sam37). Wyniki analizy filogenetycznej wskazują, iż białko Tob55 pochodzi od bakteryjnego białka Omp85, podczas gdy inne mitochondrialne białka o strukturze beczułki b nie mają homologów wśród białek bakteryjnych.Item Organizacja aparatu importu białka do mitochondriów – perspektywa filogenetyczna(2016) Kmita, Hanna; Wojtkowska, MałgorzataPrawidłowe funkcjonowanie mitochondriów, i w konsekwencji komórek eukariotycznych, wymaga bezwzględnie importu większości białek mitochondrialnych. Proces ten może przebiegać różnymi drogami, a w ich powstaniu uczestniczą złożone kompleksy białkowe, nazywane kompleksami importowymi, zlokalizowane we wszystkich przedziałach mitochondrialnych, w tym w obu błonach mitochondrialnych. Niniejsze opracowanie służy podsumowaniu aktualnego stanu wiedzy dotyczącego organizacji kompleksów importowych u przedstawicieli wyróżnianych obecnie różnych linii rozwojowych organizmów eukariotycznych. Wyłaniający się obraz, mimo braku wielu danych, wskazuje na zróżnicowanie organizacji tych kompleksów, szczególnie widoczne w przypadku kompleksu TOM, co może mieć istotne implikacje natury ewolucyjnej jak i aplikacyjnej.Item Phylogenetic analysis of mitochondrial outer membrane β-barrel channels(2012) Wojtkowska, Małgorzata; Jąkalski, Marcin; Pieńkowska, Joanna R.; Stobienia, Olgierd; Karachitos, Andonis; Przytycka, Teresa M.; Weiner, January; Kmita, Hanna; Makałowski, WojciechTransport of molecules across mitochondrial outer membrane is pivotal for a proper function of mitochondria. The transport pathways across the membrane are formed by ion channels that participate in metabolite exchange between mitochondria and cytoplasm (voltage-dependent anion-selective channel, VDAC) as well as in import of proteins encoded by nuclear genes (Tom40 and Sam50/Tob55). VDAC, Tom40, and Sam50/Tob55 are present in all eukaryotic organisms, encoded in the nuclear genome, and have β-barrel topology. We have compiled data sets of these protein sequences and studied their phylogenetic relationships with a special focus on the position of Amoebozoa. Additionally, we identified these protein-coding genes in Acanthamoeba castellanii and Dictyostelium discoideum to complement our data set and verify the phylogenetic position of these model organisms. Our analysis show that mitochondrial β-barrel channels from Archaeplastida (plants) and Opisthokonta (animals and fungi) experienced many duplication events that resulted in multiple paralogous isoforms and form well-defined monophyletic clades that match the current model of eukaryotic evolution. However, in representatives of Amoebozoa, Chromalveolata, and Excavata (former Protista), they do not form clearly distinguishable clades, although they locate basally to the plant and algae branches. In most cases, they do not posses paralogs and their sequences appear to have evolved quickly or degenerated. Consequently, the obtained phylogenies of mitochondrial outer membrane β-channels do not entirely reflect the recent eukaryotic classification system involving the six supergroups: Chromalveolata, Excavata, Archaeplastida, Rhizaria, Amoebozoa, and Opisthokonta.Item Recovery from anhydrobiosis in the tardigrade Paramacrobiotus experimentalis: Better to be young than old and in a group than alone(Heliyon, 2024) Nagwani, Amit Kumar; Melosik, Iwona; Kaczmarek, Łukasz; Kmita, HannaDesiccation-tolerant organisms can survive dehydration in a state of anhydrobiosis. Tardigrades can recover from anhydrobiosis at any life stage and are considered among the toughest animals on Earth. However, the factors that influence recovery from anhydrobiosis are not well understood. The study aimed to evaluate the effect of sex, age, the presence of other individuals and the combination of the number and duration of anhydrobiosis episodes on the recovery of Paramacrobiotus experimentalis. The activity of 1200 individuals for up to 48 h after rehydration was evaluated using analysis of variance (ANOVA). Age was the main factor influencing return to activity, followed by the combination of number and duration of anhydrobiosis episodes, influence of the presence of other individuals, and sex. More individuals returned to activity after repeated short than repeated long anhydrobiosis episodes and older individuals were less likely to recover than younger individuals. In addition, when compared to single animals, the presence of other individuals resulted in higher number of active animals after dehydration and rehydration. The effect of sex was significant, but there was no general tendency for one sex to recover from anhydrobiosis better than the other one. The results contribute to a better understanding of the anhydrobiosis ability of Paramacrobiotus experimentalis and provide background for full explanation of molecular, cellular and environmental mechanisms of anhydrobiosis.