Leukemia is a clonal malignant disease originated in a single cell and characterized by the accumulation of abnormal lymphoid cells. The nature of the leukemic stem cell (LSC) has been a subject of ...continuing discussion, given the fact that human disease is diagnosed at late stages and cannot be monitored during its natural evolution from its cell of origin. Animal models provide a means to determine the leukemic initiating cell and the causes of malignancy, and to develop new treatments. Recent findings in mice have shown that cancer stem cells can initially arise through a reprogramming-like mechanism when the oncogene expression is targeted to the mouse stem cell compartment (Garcia-Ramirez et al., EMBO J 37(14):298783, 2018; Martin-Lorenzo et al., Cancer Res 78 (10):2669-2679, 2018; Perez-Caro et al., EMBO J 28(1):8-20, 2009; Rodriguez-Hernandez et al., Cancer Res 77(16):4365-4377, 2017). If leukemia arises through reprogramming processes, then perhaps many of the oncogenes that initiate tumor formation might be dispensable for tumor progression and maintenance. Leukemia will be modeled in the mice only if we are able to target the right cancer-initiating cell with a precise given oncogene. In the last years, some examples have already started to appear in the literature showing that targeting oncogene expression to the stem cell compartment in model mice might be the correct way of reproducing the genotype-phenotype correlations found in human leukemias (Garcia-Ramirez et al., EMBO J 37(14):298783, 2018; Martin-Lorenzo et al., Cancer Res 78 (10):2669-2679, 2018; Perez-Caro et al., EMBO J 28(1):8-20, 2009; Rodriguez-Hernandez et al., Cancer Res 77(16):4365-4377, 2017). This chapter addresses how to generate LSCs by transgenesis in a way that makes the resulting animal models valuable tools to reproduce and understand leukemogenesis, and for the development of therapeutic applications like drug discovery or biomarker identification.
To investigate how ligninolytic peroxidases acquired the uniquely high redox potential they show today, their ancestors were resurrected and characterized. Unfortunately, the transient Compounds I ...(CI) and II (CII) from peroxide activation of the enzyme resting state (RS) are unstable. Therefore, the reduction potentials (E°′) of the three redox couples (CI/RS, CI/CII and CII/RS) were estimated (for the first time in a ligninolytic peroxidase) from equilibrium concentrations analyzed by stopped‐flow UV/Vis spectroscopy. Interestingly, the E°′ of rate‐limiting CII reduction to RS increased 70 mV from the common peroxidase ancestor to extant lignin peroxidase (LiP), and the same boost was observed for CI/RS and CI/CII, albeit with higher E°′ values. A straightforward correlation was found between the E°′ value and the progressive displacement of the proximal histidine Hϵ1 chemical shift in the NMR spectra, due to the higher paramagnetic effect of the heme Fe3+. More interestingly, the E°′ and NMR data also correlated with the evolutionary time, revealing that ancestral peroxidases increased their reduction potential in the evolution to LiP thanks to molecular rearrangements in their heme pocket during the last 400 million years.
E°′ in evolution: Natural evolution leading to high redox potential lignin peroxidases shows a progressive movement of the proximal histidine relative to heme cofactor. This structural change correlated with the increase of redox potential that could be estimated, for the first time, from stopped‐flow equilibrium after enzyme resurrection.
Latinx immigrants living in the United States often experience the negative effects of systemic oppression, which may lead to psychological distress, including ethno-racial trauma. We define ...ethno-racial trauma as the individual and/or collective psychological distress and fear of danger that results from experiencing or witnessing discrimination, threats of harm, violence, and intimidation directed at ethno-racial minority groups. This form of trauma stems from a legacy of oppressive laws, policies, and practices. Using an intersectionality framework, this article discusses the complex ways in which interlocking systems of oppression (e.g., racism, ethnocentrism, nativism, sexism) and anti-immigrant policies impact Latinxs individuals, families, and communities. The article also presents a framework to stimulate healing from ethno-racial trauma titled, HEART (Healing Ethno And Racial Trauma). Grounded in the principles of Liberation Psychology and trauma-informed care, the framework is composed of four phases. Each phase is accompanied by a goal to assist clinicians in helping individuals, families, and communities to achieve growth, wellness, and healing. The main objective of each phase is for Latinx immigrants to find relief, gain awareness, and cope with systemic oppression while encouraging resistance and protection from the external forces that cause ethno-racial trauma. Overall, our intention and hopeful expectation is that the content presented in this article serves as a call to action for psychologists to make psychology a Sanctuary Discipline by using and integrating intersectionality theory, trauma-informed care, and Liberation Psychology into policy, research, and practice with Latinx immigrants.
Acetic acid bacteria (AAB) and other members of the complex microbiotas, whose activity is essential for vinegar production, display biodiversity and richness that is difficult to study in depth due ...to their highly selective culture conditions. In recent years, liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) has emerged as a powerful tool for rapidly identifying thousands of proteins present in microbial communities, offering broader precision and coverage. In this work, a novel method based on LC–MS/MS was established and developed from previous studies. This methodology was tested in three studies, enabling the characterization of three submerged acetification profiles using innovative raw materials (synthetic alcohol medium, fine wine, and craft beer) while working in a semicontinuous mode. The biodiversity of existing microorganisms was clarified, and both the predominant taxa (Komagataeibacter, Acetobacter, Gluconacetobacter, and Gluconobacter) and others never detected in these media (Asaia and Bombella, among others) were identified. The key functions and adaptive metabolic strategies were determined using comparative studies, mainly those related to cellular material biosynthesis, energy-associated pathways, and cellular detoxification processes. This study provides the groundwork for a highly reliable and reproducible method for the characterization of microbial profiles in the vinegar industry.
It has been noted that in large solar energetic particle (SEP) events, the peak intensities show an East-West asymmetry with respect to the source flare locations. Using the 2D improved Particle ...Acceleration and Transport in the Heliosphere (iPATH) model, we investigate the origin of this longitudinal trend. We consider multiple cases with different solar wind speeds and eruption speeds of the coronal mass ejections (CMEs) and fit the longitudinal distributions of time-averaged fluence by symmetric/asymmetric Gaussian functions with three time intervals of 8, 24 and 48 hr after the flare onset time respectively. The simulation results are compared with a statistical study of three-spacecraft events. We suggest that the East-West asymmetry of SEP fluence and peak intensity can be primarily caused the combined effect of an extended shock acceleration process and the evolution of magnetic field connection to the shock front. Our simulations show that the solar wind speed and the CME speed are important factors determining the East-West fluence asymmetry.
Assessing historical environmental conditions linked to habitat colonization is important for understanding long‐term resilience and improving conservation and restoration efforts. Such information ...is lacking for the seagrass Zostera marina, an important foundation species across cold‐temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20‐ and 24‐fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services.
Plain Language Summary
This study investigated the historical colonization of eelgrass (Zostera marina), an important marine vascular plant in cold‐temperate coastal regions. Sediment cores from eelgrass meadows on the Swedish west coast dating back as far as 14,000 years were examined to understand the time‐course of eelgrass colonization and the subsequent modification of the environment. We found that eelgrass colonization began approximately 2,000 years ago, coinciding with the development of shallow, sheltered conditions that favored eelgrass growth. As eelgrass became established, this led to substantial habitat and sediment changes, including a 20‐ and 24‐fold increase in carbon and nitrogen accumulation, respectively. This highlights the crucial role of eelgrass as a provider of important ecosystem services, such as regulation of climate, nutrient retention, and sediment protection. We also examined the potential effects of climate change on eelgrass growth and health, predicting that decreased water clarity and altered water flow pose the greatest risks. Overall, this study adds valuable insights into the relationship between eelgrass and its environment, aiding in conservation and restoration efforts to mitigate climate change and maintain essential ecosystem services. It emphasizes the importance of specific environmental conditions for successful eelgrass colonization and restoration.
Key Points
Decreased hydrodynamics and water depth created a favorable environment for eelgrass establishment about 2,000 years ago
Carbon and nitrogen burial increased in order of magnitudes following seagrass colonization
Paleoecological information on environmental conditions linked to seagrass colonization can aid conservation and restoration efforts
Summary
Lignin is the second most abundant constituent of the cell wall of vascular plants, where it protects cellulose towards hydrolytic attack by saprophytic and pathogenic microbes. Its removal ...represents a key step for carbon recycling in land ecosystems, as well as a central issue for industrial utilization of plant biomass. The lignin polymer is highly recalcitrant towards chemical and biological degradation due to its molecular architecture, where different non‐phenolic phenylpropanoid units form a complex three‐dimensional network linked by a variety of ether and carbon–carbon bonds. Ligninolytic microbes have developed a unique strategy to handle lignin degradation based on unspecific one‐electron oxidation of the benzenic rings in the different lignin substructures by extracellular haemperoxidases acting synergistically with peroxide‐generating oxidases. These peroxidases posses two outstanding characteristics: (i) they have unusually high redox potential due to haem pocket architecture that enables oxidation of non‐phenolic aromatic rings, and (ii) they are able to generate a protein oxidizer by electron transfer to the haem cofactor forming a catalytic tryptophanyl‐free radical at the protein surface, where it can interact with the bulky lignin polymer. The structure–function information currently available is being used to build tailor‐made peroxidases and other oxidoreductases as industrial biocatalysts.
Thiamine is a crucial cofactor involved in the maintenance of carbohydrate metabolism and participates in multiple cellular metabolic processes within the cytosol, mitochondria, and peroxisomes. ...Currently, four genetic defects have been described causing impairment of thiamine transport and metabolism: SLC19A2 dysfunction leads to diabetes mellitus, megaloblastic anemia and sensory‐neural hearing loss, whereas SLC19A3, SLC25A19, and TPK1‐related disorders result in recurrent encephalopathy, basal ganglia necrosis, generalized dystonia, severe disability, and early death. In order to achieve early diagnosis and treatment, biomarkers play an important role. SLC19A3 patients present a profound decrease of free‐thiamine in cerebrospinal fluid (CSF) and fibroblasts. TPK1 patients show decreased concentrations of thiamine pyrophosphate in blood and muscle. Thiamine supplementation has been shown to improve diabetes and anemia control in Rogers' syndrome patients due to SLC19A2 deficiency. In a significant number of patients with SLC19A3, thiamine improves clinical outcome and survival, and prevents further metabolic crisis. In SLC25A19 and TPK1 defects, thiamine has also led to clinical stabilization in single cases. Moreover, thiamine supplementation leads to normal concentrations of free‐thiamine in the CSF of SLC19A3 patients. Herein, we present a literature review of the current knowledge of the disease including related clinical phenotypes, treatment approaches, update of pathogenic variants, as well as in vitro and in vivo functional models that provide pathogenic evidence and propose mechanisms for thiamine deficiency in humans.
Versatile peroxidase (VP) from the white-rot fungus Pleurotus eryngii is a high redox potential peroxidase of biotechnological interest able to oxidize a wide range of recalcitrant substrates ...including lignin, phenolic and non-phenolic aromatic compounds and dyes. However, the relatively low stability towards pH of this and other fungal peroxidases is a drawback for their industrial application. A strategy based on the comparative analysis of the crystal structures of VP and the highly pH-stable manganese peroxidase (MnP4) from Pleurotus ostreatus was followed to improve the VP pH stability. Several interactions, including hydrogen bonds and salt bridges, and charged residues exposed to the solvent were identified as putatively contributing to the pH stability of MnP4. The eight amino acid residues responsible for these interactions and seven surface basic residues were introduced into VP by directed mutagenesis. Furthermore, two cysteines were also included to explore the effect of an extra disulfide bond stabilizing the distal Ca2+ region. Three of the four designed variants were crystallized and new interactions were confirmed, being correlated with the observed improvement in pH stability. The extra hydrogen bonds and salt bridges stabilized the heme pocket at acidic and neutral pH as revealed by UV-visible spectroscopy. They led to a VP variant that retained a significant percentage of the initial activity at both pH 3.5 (61% after 24 h) and pH 7 (55% after 120 h) compared with the native enzyme, which was almost completely inactivated. The introduction of extra solvent-exposed basic residues and an additional disulfide bond into the above variant further improved the stability at acidic pH (85% residual activity at pH 3.5 after 24 h when introduced separately, and 64% at pH 3 when introduced together). The analysis of the results provides a rational explanation to the pH stability improvement achieved.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The VPs (versatile peroxidases) secreted by white-rot fungi are involved in the natural decay of lignin. In the present study, a fusion gene containing the VP from Pleurotus eryngii was subjected to ...six rounds of directed evolution, achieving a level of secretion in Saccharomyces cerevisiae (21 mg/l) as yet unseen for any ligninolytic peroxidase. The evolved variant for expression harboured four mutations and increased its total VP activity 129-fold. The signal leader processing by the STE13 protease at the Golgi compartment changed as a consequence of overexpression, retaining the additional N-terminal sequence Glu-Ala-Glu-Ala that enhanced secretion. The engineered N-terminally truncated variant displayed similar biochemical properties to those of the non-truncated counterpart in terms of kinetics, stability and spectroscopic features. Additional cycles of evolution raised the T50 8°C and significantly increased the enzyme's stability at alkaline pHs. In addition, the Km for H2O2 was enhanced up to 15-fold while the catalytic efficiency was maintained, and there was an improvement in peroxide stability (with half-lives for H2O2 of 43 min at a H2O2/enzyme molar ratio of 4000:1). Overall, the directed evolution approach described provides a set of strategies for selecting VPs with improvements in secretion, activity and stability.
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