197 research outputs found
Identification of proteins related to microspore embryogenesis responsiveness in anther cultures of winter triticale (×Triticosecale Wittm.)
Tekla z Wodzickich Małachowska jako protektorka Towarzystwa Dobroczynności w Krakowie. Przyczynek do biografii
The person I described in my article is Tekla Małachowska nee Wodzicka (1764–1829), daughter of Eliasz, a starost of Krakow, and Ludwika Wielopolska. Tekla was the second wife of Piotr Małachowski (1730–1799), the governor of Krakow province. After her husband’s death, she settled in Stopnice near Krakow. She came back to public life during the period of the Duchy of Warsaw. Then she moved to Krakow and rendered services to the cause of organizing the Charity Association in Krakow. In February 1817 Małachowska became the first President of the Charity Association. She was taking care of the persons under the Charity Association’s charge, organizing charitable concerts and balls where she assembled money for the Charity Association. Thanks to her personal qualities and welfare-and-social work Małachowska gained the general respect of community. Her friends were not only among the representatives of aristocratic houses but also leading intellectualists of the time, such as Jan Śniadecki, who bequeathed 12 thousands Polish zlotys for education of children in Niedźwiedź. Tekla Małachowska died on 22 December 1829, and was buried with her husband in Niedźwiedź In token of gratitude for her protection, on 11 February 1821 the Charity Association resolved to hang the portraits painted on metal of Tekla Małachowska and Stanisław Mieroszewski in the Chapel of the Poor in the Wawel Castle. These portraits, stamped in copper, were distributed later among the members of the Charity Association. After Małachowska’s death, a funeral mass for her soul was said on 16 January 1830 was. A few years later that sermon was recorded in the commemorative book/visitor’s book of the deceased benefactors of the Charity Association in Cracow.Bohaterką tekstu jest Tekla z Wodzickich Małachowska (1764–1829), córka Eliasza, starosty krakowskiego, i Ludwiki z Wielopolskich. Tekla była drugą żoną Piotra Małachowskiego (ok. 1730–1799), wojewody krakowskiego. Po śmierci męża zamieszkała w Stopnicy pod Krakowem. Do życia publicznego powróciła w okresie Księstwa Warszawskiego. Wtedy przeniosła się do Krakowa. Włączyła się w działania przy organizacji Towarzystwa Dobroczynności. W lutym 1817 roku została pierwszą prezeską Towarzystwa. Troszczyła się o swoich podopiecznych, organizowała koncerty charytatywne, bale, na których zbierała pieniądze dla Towarzystwa. Walory osobiste i działalność społeczno-charytatywna zyskały jej powszechny szacunek. Do grona przyjaciół zaliczali ją nie tylko przedstawiciele rodów magnackich osiadłych w Krakowie, ale także czołowi intelektualiści epoki, m.in. Jan Śniadecki. Testamentem zapisała 12 tys. złp na edukację dzieci w Niedźwiedziu. Zmarła 22 grudnia 1929 roku, pochowana obok męża w Niedźwiedziu. Towarzystwo było bardzo wdzięczne protektorce za opiekę, dlatego 11 lutego 1821 roku uchwaliło, aby malowane na blasze portrety jej i Stanisława Mieroszewskiego zawiesić w kaplicy ubogich na Wawelu. Portrety te, odbite na miedzi, później rozpowszechnione zostały wśród członków towarzystwa. Po śmierci Małachowskiej 16 stycznia 1830 roku w kaplicy ubogich odprawiono żałobne nabożeństwo za jej duszę. Wygłoszone na nim wtedy kazanie ku czci Tekli Małachowskiej kilka lat później wpisano do pamiątkowej Księgi zmarłych dobroczyńców Towarzystwa
Changes in gene expression patterns associated with microspore embryogenesis in hexaploid triticale (×Triticosecale Wittm.)
Glutathione provides antioxidative defence and promotes microspore-derived embryo development in isolated microspore cultures of triticale (xTriticosecale Wittm.)
The efficiency of microspore embryogenesis (ME) is determined by the complex network of internal and environmental factors. Among them, the efficient defence against oxidative stress seems to be one of the most important. The present study confirms this hypothesis showing the positive effect of glutathionethe most abundant cellular antioxidanton ME in isolated microspore cultures of triticale (xTriticosecale Wittm.). For the first time, low temperature (LT) pre-treatment of tillers was combined with the exogenous application of glutathione and associated with the total activity of low-molecular weight antioxidants, the endogenous content and redox status of glutathione, and the effectiveness of ME. The results indicate that efficient antioxidative defence is the first, although not the only, prerequisite for effective ME. In responsive genotypes, LT alone stimulated antioxidative defence and decreased cell redox status, which was associated with increased cell viability and high frequency (ca. 20%) of microspore reprogramming. Application of glutathione had no effect either on the microspore viability or on the initial number of embryogenic microspores. However, it increased the number of embryo-like structures, probably by stimulating the next phases of its development. In recalcitrant genotypes, the main role of glutathione seems to be its participation in cell protection from oxidative stress. However, even enhanced antioxidative activity, which sustained cell viability and increased the number of embryogenic microspores, was insufficient for efficient haploid/doubled haploid plant production. Evidently, there are still other defective elements in the complex network of factors that regulate the process of ME
Over-expression of the molecular chaperone Hsp104 in Saccharomyces cerevisiae results in the malpartition of [PSI + ] propagons.
Structural basis for the disaggregase activity and regulation of Hsp104
The Hsp104 disaggregase is a two-ring ATPase machine that rescues various forms of non-native proteins including the highly resistant amyloid fibers. The structural-mechanistic underpinnings of how the recovery of toxic protein aggregates is promoted and how this potent unfolding activity is prevented from doing collateral damage to cellular proteins are not well understood. Here, we present structural and biochemical data revealing the organization of Hsp104 from Chaetomium thermophilum at 3.7 angstrom resolution. We show that the coiled-coil domains encircling the disaggregase constitute a 'restraint mask' that sterically controls the mobility and thus the unfolding activity of the ATPase modules. In addition, we identify a mechanical linkage that coordinates the activity of the two ATPase rings and accounts for the high unfolding potential of Hsp104. Based on these findings, we propose a general model for how Hsp104 and related chaperones operate and are kept under control until recruited to appropriate substrates
Hsp104-Dependent Remodeling of Prion Complexes Mediates Protein-Only Inheritance
Inheritance of phenotypic traits depends on two key events: replication of the determinant of that trait and partitioning of these copies between mother and daughter cells. Although these processes are well understood for nucleic acid–based genes, the mechanisms by which protein-only or prion-based genetic elements direct phenotypic inheritance are poorly understood. Here, we report a process crucial for inheritance of the Saccharomyces cerevisiae prion [PSI(+)], a self-replicating conformer of the Sup35 protein. By tightly controlling expression of a Sup35-GFP fusion, we directly observe remodeling of existing Sup35([PSI+]) complexes in vivo. This dynamic change in Sup35([PSI+]) is lost when the molecular chaperone Hsp104, a factor essential for propagation of all yeast prions, is functionally impaired. The loss of Sup35([PSI+]) remodeling by Hsp104 decreases the mobility of these complexes in the cytosol, creates a segregation bias that limits their transmission to daughter cells, and consequently diminishes the efficiency of conversion of newly made Sup35 to the prion form. Our observations resolve several seemingly conflicting reports on the mechanism of Hsp104 action and point to a single Hsp104-dependent event in prion propagation
The Number and Transmission of [PSI+] Prion Seeds (Propagons) in the Yeast Saccharomyces cerevisiae
Yeast (Saccharomyces cerevisiae) prions are efficiently propagated and the on-going generation and transmission of prion seeds (propagons) to daughter cells during cell division ensures a high degree of mitotic stability. The reversible inhibition of the molecular chaperone Hsp104p by guanidine hydrochloride (GdnHCl) results in cell division-dependent elimination of yeast prions due to a block in propagon generation and the subsequent dilution out of propagons by cell division.Analysing the kinetics of the GdnHCl-induced elimination of the yeast [PSI+] prion has allowed us to develop novel statistical models that aid our understanding of prion propagation in yeast cells. Here we describe the application of a new stochastic model that allows us to estimate more accurately the mean number of propagons in a [PSI+] cell. To achieve this accuracy we also experimentally determine key cell reproduction parameters and show that the presence of the [PSI+] prion has no impact on these key processes. Additionally, we experimentally determine the proportion of propagons transmitted to a daughter cell and show this reflects the relative cell volume of mother and daughter cells at cell division.While propagon generation is an ATP-driven process, the partition of propagons to daughter cells occurs by passive transfer via the distribution of cytoplasm. Furthermore, our new estimates of n(0), the number of propagons per cell (500-1000), are some five times higher than our previous estimates and this has important implications for our understanding of the inheritance of the [PSI+] and the spontaneous formation of prion-free cells
Biophysical approaches for the study of interactions between molecular chaperones and protein aggregates
[SWI+], the Prion Formed by the Chromatin Remodeling Factor Swi1, Is Highly Sensitive to Alterations in Hsp70 Chaperone System Activity
The yeast prion [SWI+], formed of heritable amyloid aggregates of the Swi1 protein, results in a partial loss of function of the SWI/SNF chromatin-remodeling complex, required for the regulation of a diverse set of genes. Our genetic analysis revealed that [SWI+] propagation is highly dependent upon the action of members of the Hsp70 molecular chaperone system, specifically the Hsp70 Ssa, two of its J-protein co-chaperones, Sis1 and Ydj1, and the nucleotide exchange factors of the Hsp110 family (Sse1/2). Notably, while all yeast prions tested thus far require Sis1, [SWI+] is the only one known to require the activity of Ydj1, the most abundant J-protein in yeast. The C-terminal region of Ydj1, which contains the client protein interaction domain, is required for [SWI+] propagation. However, Ydj1 is not unique in this regard, as another, closely related J-protein, Apj1, can substitute for it when expressed at a level approaching that of Ydj1. While dependent upon Ydj1 and Sis1 for propagation, [SWI+] is also highly sensitive to overexpression of both J-proteins. However, this increased prion-loss requires only the highly conserved 70 amino acid J-domain, which serves to stimulate the ATPase activity of Hsp70 and thus to stabilize its interaction with client protein. Overexpression of the J-domain from Sis1, Ydj1, or Apj1 is sufficient to destabilize [SWI+]. In addition, [SWI+] is lost upon overexpression of Sse nucleotide exchange factors, which act to destabilize Hsp70's interaction with client proteins. Given the plethora of genes affected by the activity of the SWI/SNF chromatin-remodeling complex, it is possible that this sensitivity of [SWI+] to the activity of Hsp70 chaperone machinery may serve a regulatory role, keeping this prion in an easily-lost, meta-stable state. Such sensitivity may provide a means to reach an optimal balance of phenotypic diversity within a cell population to better adapt to stressful environments
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