Zum Rückgang von RomaschülrInnen an Sonderschulen im Burgenland

Die Arbeit befasst sich mit der schulischen Situation der Roma in Mittel- und Osteuropa wobei vor allem der überproportional hohe Anteil dieser Minderheit an Sonderschulen thematisiert wird. Konkret wird dabei auf die Situation der Roma österreichweit und, im Speziellen, auf jene der Burgenland-Roma in Oberwart eingegangen. Mit Hilfe qualitativer Interviews wurden mögliche Gründe für den vor Ort stattgefundenen, anteilsmäßigen Rückgang von Kindern aus Romafamilien an der Sonderschule untersucht

Chloroplast Transition Metal Regulation for Efficient Photosynthesis

Schmidt SB, Eisenhut M, Schneider A. Chloroplast Transition Metal Regulation for Efficient Photosynthesis. Trends in Plant Science. 2020;25(8):817-828

Transcriptional response of the extremophile red alga Cyanidioschyzon merolae to changes in CO2 concentrations

Rademacher N, Wrobel TJ, Rossoni AW, et al. Transcriptional response of the extremophile red alga Cyanidioschyzon merolae to changes in CO2 concentrations. Journal of Plant Physiology. 2017;217:49-56.Cyanidioschyzon merolae (C. merolae) is an acidophilic red alga growing in a naturally low carbon dioxide (CO2) environment. Although it uses a ribulose 1,5-bisphosphate carboxylase/oxygenase with high affinity for CO2, the survival of C. merolae relies on functional photorespiratory metabolism. In this study, we quantified the transcriptomic response of C. merolae to changes in CO2 conditions. We found distinct changes upon shifts between CO2 conditions, such as a concerted up-regulation of photorespiratory genes and responses to carbon starvation. We used the transcriptome data set to explore a hypothetical CO2 concentrating mechanism in C. merolae, based on the assumption that photorespiratory genes and possible candidate genes involved in a CO2 concentrating mechanism are co-expressed. A putative bicarbonate transport protein and two a-carbonic anhydrases were identified, which showed enhanced transcript levels under reduced CO2 conditions. Genes encoding enzymes of a PEPCK-type C-4 pathway were co-regulated with the photorespiratory gene cluster. We propose a model of a hypothetical low CO2 compensation mechanism in C. merolae integrating these low CO2-inducible components

Photorespiration Is Crucial for Dynamic Response of Photosynthetic Metabolism and Stomatal Movement to Altered CO2 Availability

Eisenhut M, Bräutigam A, Timm S, et al. Photorespiration Is Crucial for Dynamic Response of Photosynthetic Metabolism and Stomatal Movement to Altered CO2 Availability. Molecular Plant. 2017;10(1):47-61.The photorespiratory pathway or photorespiration is an essential process in oxygenic photosynthetic organisms, which can reduce the efficiency of photosynthetic carbon assimilation and is hence frequently considered as a wasteful process. By comparing the response of the wild-type plants and mutants impaired in photorespiration to a shift in ambient CO2 concentrations, we demonstrate that photorespiration also plays a beneficial role during short-term acclimation to reduced CO2 availability. The wild-type plants responded with few differentially expressed genes, mostly involved in drought stress, which is likely a consequence of enhanced opening of stomata and concomitant water loss upon a shift toward low CO2. In contrast, mutants with impaired activity of photorespiratory enzymes were highly stressed and not able to adjust stomatal conductance to reduced external CO2 availability. The transcriptional response of mutant plants was congruent, indicating a general reprogramming to deal with the consequences of reduced CO2 availability, signaled by enhanced oxygenation of ribulose-1,5-bisphosphate and amplified by the artificially impaired photorespiratory metabolism. Central in this reprogramming was the pronounced reallocation of resources from growth processes to stress responses. Taken together, our results indicate that unrestricted photorespiratory metabolism is a prerequisite for rapid physiological acclimation to a reduction in CO2 availability

Flavodiiron Proteins in Oxygenic Photosynthetic Organisms: Photoprotection of Photosystem II by Flv2 and Flv4 in Synechocystis sp. PCC 6803

BACKGROUND: Flavodiiron proteins (FDPs) comprise a group of modular enzymes that function in oxygen and nitric oxide detoxification in Bacteria and Archaea. The FDPs in cyanobacteria have an extra domain as compared to major prokaryotic enzymes. The physiological role of cyanobacteria FDPs is mostly unknown. Of the four putative flavodiiron proteins (Flv1-4) in the cyanobacterium Synechocystis sp. PCC 6803, a physiological function in Mehler reaction has been suggested for Flv1 and Flv3. PRINCIPAL FINDINGS: We demonstrate a novel and crucial function for Flv2 and Flv4 in photoprotection of photosystem II (PSII) in Synechocystis. It is shown that the expression of Flv2 and Flv4 is high under air level of CO(2) and negligible at elevated CO(2). Moreover, the rate of accumulation of flv2 and flv4 transcripts upon shift of cells from high to low CO(2) is strongly dependent on light intensity. Characterization of FDP inactivation mutants of Synechocystis revealed a specific decline in PSII centers and impaired translation of the D1 protein in Delta flv2 and Delta flv4 when grown at air level CO(2) whereas at high CO(2) the Flvs were dispensable. Delta flv2 and Delta flv4 were also more susceptible to high light induced inhibition of PSII than WT or Delta flv1 and Delta flv3. SIGNIFICANCE: Analysis of published sequences revealed the presence of cyanobacteria-like FDPs also in some oxygenic photosynthetic eukaryotes like green algae, mosses and lycophytes. Our data provide evidence that Flv2 and Flv4 have an important role in photoprotection of water-splitting PSII against oxidative stress when the cells are acclimated to air level CO(2). It is conceivable that the function of FDPs has changed during evolution from protection against oxygen in anaerobic microbes to protection against reactive oxygen species thus making the sustainable function of oxygen evolving PSII possible. Higher plants lack FDPs and distinctly different mechanisms have evolved for photoprotection of PSII

Manganese Homeostasis in Cyanobacteria

Eisenhut M. Manganese Homeostasis in Cyanobacteria. Plants. 2020;9(1): 18.Manganese (Mn) is essential for life on earth. As a catalyst of the water oxidation reaction within photosystem II, the trace metal is responsible for the evolution of virtually all oxygen in the earth’s atmosphere. Mn acts furthermore as an activator or cofactor of numerous enzymes involved in reactive oxygen species scavenging or central and secondary metabolism. While the sufficient supply of oxygenic photosynthetic organisms with Mn is obvious for maintaining photosynthetic activity, the avoidance of cellular Mn overload is also critical. In this review, current knowledge about the Mn homeostasis network in the model cyanobacterium Synechocystis sp. PCC 6803 is presented, including transporters and regulators

Manganese Homeostasis in Cyanobacteria

Manganese (Mn) is essential for life on earth. As a catalyst of the water oxidation reaction within photosystem II, the trace metal is responsible for the evolution of virtually all oxygen in the earth’s atmosphere. Mn acts furthermore as an activator or cofactor of numerous enzymes involved in reactive oxygen species scavenging or central and secondary metabolism. While the sufficient supply of oxygenic photosynthetic organisms with Mn is obvious for maintaining photosynthetic activity, the avoidance of cellular Mn overload is also critical. In this review, current knowledge about the Mn homeostasis network in the model cyanobacterium Synechocystis sp. PCC 6803 is presented, including transporters and regulators

Four plus one: vacuoles serve in photorespiration

Timm S, Eisenhut M. Four plus one: vacuoles serve in photorespiration. Trends in Plant Science . 2023.Photorespiration is inevitable for oxygenic photosynthesis. It has fascinated researchers over decades because of its multicompartmental organization. Recently, Lin and Tsay identified a vacuole glycerate transporter contributing to photorespiratory metabolism under short-term nitrogen depletion. This key finding adds a fifth interacting subcellular compartment and extends the photorespiratory metabolic repair module. Copyright © 2023 Elsevier Ltd. All rights reserved

Using Publicly Available RNA-seq Data for Expression Analysis of Genes of Interest

Wulf D, Bräutigam A, Eisenhut M. Using Publicly Available RNA-seq Data for Expression Analysis of Genes of Interest. Methods in Molecular Biology. 2024;2792:241-250.RNA-seq data in publicly available repositories enable the efficient reanalysis of transcript abundances in existing experiments. Graphical user interfaces usually only allow the visual inspection of a single gene and of predefined experiments. Here, we describe how experiments are selected from the Sequence Read Archive or the European Nucleotide Archive, how data is efficiently mapped onto a reference transcriptome, and how global transcript abundances and patterns are inspected. We exemplarily apply this analysis pipeline to study the expression of photorespiration-related genes in photosynthetic organisms, such as cyanobacteria, and to identify conditions under which photorespiratory transcript abundances are enhanced. © 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature

Improving crop yield

Eisenhut M, Weber APM. Improving crop yield. Science. 2019;363(6422):32-33.Synthetic photorespiration bypass increases crop yieldThe enzyme ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBisCO) is one of the most abundant proteins on Earth. During photosynthesis, it assimilates atmospheric CO2into biomass and hence is a major driver of the global carbon cycle. However, the enzyme is catalytically imperfect. It accepts not only CO2as a substrate, but also O2, which leads to the formation of a toxic byproduct, 2-phosphoglycolate (2-PGlycolate) (1). The metabolic pathway photorespiration detoxifies 2-PGlycolate, and it is essential for performing photosynthesis in an O2-containing atmosphere. Importantly, photorespiration causes a 20 to 50% yield penalty, depending on the environmental conditions and the type of photosynthesis employed (2). Multiple attempts have been undertaken to overcome this yield penalty and thereby increase biomass production in plants, with limited success to date. On page 45 of this issue, Southet al.(3) present a synthetic pathway that fully detoxifies 2-PGlycolate inside plant chloroplasts. Transgenic tobacco plants expressing this pathway show strongly enhanced biomass production in field trials, suggesting that this could be used to improve crop yields