Knock-Down of the IFR1 Protein Perturbs the Homeostasis of Reactive Electrophile Species and Boosts Photosynthetic Hydrogen Production in <i>Chlamydomonas reinhardtii</i>

Venkanna D, Südfeld C, Baier T, et al. Knock-Down of the IFR1 Protein Perturbs the Homeostasis of Reactive Electrophile Species and Boosts Photosynthetic Hydrogen Production in &lt;i&gt;Chlamydomonas reinhardtii&lt;/i&gt;. Frontiers in Plant Science. 2017;8: 1347.The protein superfamily of short-chain dehydrogenases/reductases (SDR), including members of the atypical type (aSDR), covers a huge range of catalyzed reactions and in vivo substrates. This superfamily also comprises isoflavone reductase-like (IRL) proteins, which are aSDRs highly homologous to isoflavone reductases from leguminous plants. The molecular function of IRLs in non-leguminous plants and green microalgae has not been identified as yet, but several lines of evidence point at their implication in reactive oxygen species homeostasis. The Chlamydomonas reinhardtii IRL protein IFR1 was identified in a previous study, analyzing the transcriptomic changes occurring during the acclimation to sulfur deprivation and anaerobiosis, a condition that triggers photobiological hydrogen production in this microalgae. Accumulation of the cytosolic IFR1 protein is induced by sulfur limitation as well as by the exposure of C. reinhardtii cells to reactive electrophile species (RES) such as reactive carbonyls. The latter has not been described for IRL proteins before. Over-accumulation of IFR1 in the singlet oxygen response 1 (sor1) mutant together with the presence of an electrophile response element, known to be required for SOR1-dependent gene activation as a response to RES, in the promoter of IFR1, indicate that IFR1 expression is controlled by the SOR1-dependent pathway. An implication of IFR1 into RES homeostasis, is further implied by a knock-down of IFR1, which results in a diminished tolerance toward RES. Intriguingly, IFR1 knock-down has a positive effect on photosystem II (PSII) stability under sulfur-deprived conditions used to trigger photobiological hydrogen production, by reducing PSII-dependent oxygen evolution, in C. reinhardtii. Reduced PSII photoinhibition in IFR1 knock-down strains prolongs the hydrogen production phase resulting in an almost doubled final hydrogen yield compared to the parental strain. Finally, IFR1 knock-down could be successfully used to further increase hydrogen yields of the high hydrogen-producing mutant stm6, demonstrating that IFR1 is a promising target for genetic engineering approaches aiming at an increased hydrogen production capacity of C. reinhardtii cells

Wenig Luft bring viel Biogas

Bei der anaeroben Vergärung von faserreicher Biomasse zur Produktion von Biogas erweist sich die Hydrolyse von komplexen organischen Substanzen wie Grüngut, Stroh oder Hofdünger oftmals als der geschwindigkeitsbestimmende Teilschritt. Speziell der Abbau von Cellulose und Lignocellulose ist unter anaeroben Bedingungen erschwert [1]. Ursache ist der starke Zusammenhalt zwischen den Verbindungen innerhalb der Pflanzenstruktur, die eine effektive Barriere gegenüber einem hydrolytischen oder enzymatischen Abbau bilden [2]. Durch eine Vorbehandlung des Substrates lassen sich diese komplexen biochemischen Strukturen aufbrechen. Mittels vorgeschalteter biologischer Hydrolyse kann die stabile Lignozellulosestruktur effizienter aufgeschlossen und dem anaeroben mikrobiologischen Abbau bis zum Biomethan zugänglich gemacht werden. Zur Vorbehandlung von Biomasse existiert eine Vielzahl von Verfahren und Technologien, die eine Verbesserung der anaeroben Abbaubarkeit anstreben. Sie lassen sich in physikalische, chemische und biologische Verfahren unterteilen (Fig. 1). Biologische Verfahren besitzen gegenüber den physikalischen und chemischen Verfahren oft eine Reihe von Vorteilen, aber auch einige Nachteile

Impact of stressful life event on the global functioning outcome after an assertive community treatment

Background: Assertive community treatment (ACT) was reported to be an effective treatment to improve global functioning of ultra-high risk (UHR) adolescents. However, the infl uence of stressful life event (SLE) was not extensively studied which represent our objective. Method: The SLE (encompassing adoption, migration, family member's deceased, sexual or physical abuse, etc.) of 20 UHR adolescents, treated with an ACT model, were rated. 10 adolescents having 0 to 1 SLE (mainly parents' divorce; low SLE group) were compared 10 adolescents with 2 to 5 SLE (high SLE group). The adolescents were assessed at baseline and after treatment with the Health of Nation Outcome Scale for Children and Adolescents (HoNOSCA). The HoNOSCA allowed rating different diffi culties such as behavior, symptoms, disorders and social. Results: First, results on the whole sample indicated signifi cant improvement after ACT (compared to baseline) on the total (P = .04), symptoms (P = .025) and social (P = .009) scores of the HoNOSCA. Second, the improvement on the HoNOSCA's score of the high SLE group were signifi cantly higher for the total (P = .016), symptoms (P = .019) and behavior (P = .033) scores compared to the low SLE group. Discussion/Conclusion: Globally, ACT seems to be an appropriate treatment to enhance global functioning and more specifi cally the social and symptoms diffi culties of UHR adolescents. Additionally, UHR adolescents with a high numbers of SLE were observed to have a better benefi t of the ACT on global, symptoms and behavioral diffi culties