Genetic analyses of feather pecking and related behavior traits of laying hens

Das Ziel der vorliegenden Arbeit war die Untersuchung der genetischen Fundierung von Verhaltensmerkmalen, insbesondere bei dem Merkmal Federpicken, und die Ableitung ethologischer Beziehungen zu anderen Merkmalen bei Legehennen. Hierfür standen Daten von zwei auf Federpicken divergent selektierten Linien und eine große F2-Population, welche aus diesen divergent selektierten Linien erstellt wurde, zur Verfügung. Hühner der Rasse White Leghorn wurden über 11 Generationen hinweg divergent auf hohes und niedriges Federpicken selektiert. Die ersten 5 Generationen wurden am Institut für Tierwissenschaften in Foulum, Dänemark, durchgeführt. Die weiteren Selektionsrunden fanden am Institut für Nutztierwissenschaften an der Universität Hohenheim, Deutschland, statt. Die große F2-Population, bestehend aus 960 Hennen, wurde aus der 10-ten Selektionsgeneration erzeugt und es wurde eine umfassende Datensammlung von Verhaltens- und Leistungsmerkmalen erhoben. Diese beiden Datensätze wurden zur Erstellung der nachfolgenden fünf Kapitel verwendet. In Kapitel eins werden mit den Daten der F2-Population eine quantitativ genetische Analyse von Furchtmerkmalen und Federpicken sowie aggressivem Picken durchgeführt. Furcht wurde mittels der Tonischen Immobilität, Open Field Aktivität und dem Emerge Box Test erfasst. Diese wurden sowohl im juvenilen als auch adulten Alter durchgeführt. Die Verhaltensmerkmale Federpicken und aggressives Picken wurden in Gruppen von 36 bis 40 Tieren im Alter von 27 Wochen aufgezeichnet. Die genetischen Parameter wurden mit einem linear gemischten Modell geschätzt. Aggressives Picken zeigte die höchste Heritabilität (0.27), gefolgt von Federpicken (0.14). Die Furchttestmerkmale zeigten Heritabilitäten zwischen 0.07 und 0.14. Die einzige nennenswerte genetische Korrelation zwischen den Furchtmerkmalen und Federpicken ist die tonische Immobilität im juvenilen Alter (rg=0.27). In Kapitel zwei werden unter der Verwendung eines Poisson Modells Varianzkomponenten und Heritabilitäten der Merkmale Federpicken und aggressivem Picken in unterschiedlichen Zeitperioden geschätzt. Die kurze Zeitperiode beinhaltet die Anzahl Federpicks pro 20 min und die aufsummierten Pickwerte über einen Tag ergab die mittlere Zeitperiode. Die Ergebnisse zeigten, dass die Modellierung der Daten als wiederholte Beobachtungen (kurze und mittlere Zeitperiode) und die Auswertung mittels Poisson Modell eine geeignete Methode darstellt, um wichtige permanente Umwelteffekte vom additiven Tiereffekt zu trennen. Das Ziel in Kapitel drei ist mittels Strukturgleichungsmodellen die Beziehung zwischen Federpicken und Federfressen, sowie der allgemeinen Bewegungsaktivität, zu analysieren. Die geschätzten Heritabilitäten von Federfressen, der allgemeinen Bewegungsaktivität und des Federpickens waren 0.36, 0.29 und 0.20. Die genetische Korrelation zwischen Federpicken und Federfressen (allgemeine Bewegungsaktivität) betrug 0.17 (0.04). Eine hohe genetische Korrelation mit 0.47 konnte zwischen Federfressen und der allgemeinen Bewegungsaktivität geschätzt werden. Der rekursive Effekt von Federfressen auf Federpicken war λ ̂_(FP,FE)= 0.258, und von der allgemeinen Bewegungsaktivität zum Federpicken lag bei λ ̂_(FP,GLA)= 0.046. Diese Ergebnisse implizieren, dass ein erhöhtes Federfressverhalten zu einer Erhöhung des Federpickens führt und das eine gesteigerte allgemeine Bewegungsaktivität in einer höhere Federpickanzahl resultiert. Das Ziel von Kapitel vier ist die Durchführung einer quantitativ genetischen Analyse und die Kartierung von Selektionssignaturen bei zwei divergent selektierten Legehennenlinien auf Federpickverhalten. In diesem Selektionsexperiment wurden die Linien über 11 Generation hinweg auf hohes und niedriges Federpicken selektiert. Das Pedigree und die Phänotypdaten der letzten sechs Generationen beider Linien standen für die statistische Auswertung mit einem linear gemischten Modells und einem Poisson Modell zur Verfügung. Das linear gemischte Modell eignete sich nicht zur Auswertung der Niedrigpickerdaten auf Grund der zu hohen Anzahl an Null-Werten im Beobachtungsvektor. Das Poisson Modell passte sich den Daten besser an und lieferte einen kleinen, aber kontinuierlichen genetischen Trend in beiden Linien. Aus der 11-ten Generation wurden 75 Tiere, davon 41 Hochpicker und 34 Niedrigpicker, mit dem Illumina 60K chicken Infinium iSelect chip genotypisiert. Zur Kartierung von Selektionssignaturen wurde ein FST basierten Ansatz verwendet. Es konnten 17 genomweit signifikante SNPs mit einem FST-Wert von 1 detektiert werden, das heißt die Allele sind an diesem SNP divergent fixiert. Die meisten dieser SNPs sind auf Chromosom 3 und 4 lokalisiert. Des Weiteren konnte eine Anzahl an signifikanter SNPs mit einem p-Wert von ≤ 5x10-4 und ≤ 5x10-5 kartiert werden. Basierend auf der Annahme, dass eine Selektion mehrere aufeinanderfolgende SNPs beeinflusst, konnten 13 Cluster identifiziert werden. In Kapitel fünf werden die Daten des F2-Kreuzungsexperimentes verwendet um eine genomweite Assoziationsanalyse der Merkmale Federpicken und aggressivem Pickverhalten durchzuführen. Die Ergebnisse dieser Assoziationsanalyse wurden mit den Ergebnissen des Selektionsexperiments (Kapitel vier) in einer Metaanalyse kombiniert, um diese mit denjenigen aus einer differentiellen Genexpressionsanalyse in Zusammenhang zu bringen. Hierfür wurden 817 F2-Hennen mit dem Illumina 60K chicken Infinium iSelect chip genotypisiert. Es wurde eine Single-Marker-Assoziationsanalyse durchgeführt und ein Poisson Modell verwendet. Es wurden vier genomweit signifikante SNPs für das Ausführen von aggressivem Picken detektiert, aber keine für Federpicken oder das Erhalten von aggressivem Picken. Jedoch konnte eine Reihe an signifikanten SNPs mit p≤5x10-5 für das Ausführen von Federpicken und für das Erhalten von aggressivem Picken kartiert werden. In der Metaanalyse wurden neun genomweit signifikante SNPs für Federpicken identifiziert, welche in chromosomalen Clustern (3 Mb) lokalisiert waren. Die differentielle Genexpressionsanalyse lieferte 8 von 750 untersuchten Genen, welche ein genomweit signifikant unterschiedliches Expressionslevel zeigten. Die Dissertationsschrift endet mit einer kapitelübergreifenden Diskussion.The main objective of the present study was to study the genetic foundation of behaviour traits, especially feather pecking behaviour, and to infer ethological interrelationship between certain traits of laying hens. The data of two divergently selected lines for feather pecking behaviour was available, and additionally a large F2-cross, set up from these divergently selected lines, was established. Chickens of a White Leghorn layer line were divergently selected for high and low feather pecking for 11 generations. The selection started in the Danish Institute of Animal Sciences, Foulum, Denmark, for the first six generations (0-5). Thereafter, five rounds of selection took place at the Institute of Animal Science, University of Hohenheim, Germany. The large F2-cross was established from the 10th selection generation, and a comprehensive data collection of behaviour and performance traits of 960 hens was performed. These two data sets were used for the following five research chapters. In chapter one, a quantitative genetic analysis of fear traits and feather pecking as well as aggressive pecking using data from the large F2-cross was performed. Fear was recorded by the tonic immobility test, the open field activity and the emergence box test. These were recorded at a juvenile and adult age. Behavior traits as feather pecking and aggressive pecking were recorded in groups of 36 to 40 animals at the age of 27 weeks. The genetic parameters were estimated using a linear mixed model. Aggressive pecking showed the highest heritability (0.27) followed by feather pecking (0.14). The fear test traits showed heritabilities in the range of 0.07 to 0.14. The appreciable genetic correlation between fear traits and feather pecking was tonic immobility at juvenile age (rg=0.27). In chapter two we used dispersed Poisson models to estimate variance components, heritabilities of feather and aggressive pecking of different observation periods. The short period included the number of feather pecks in 20 min and the medium period was the summed bouts within one day. The results showed that modelling the data as repeated observations (short and medium period) and analysing them with a dispersed Poisson model is a suitable option to separate the important permanent environment effects from the additive animal effects and to account for the non-normal distribution of the data. The objective of chapter three was to analyze the interrelationship between feather pecking and feather eating as well as general locomotor activity using structural equation models. The estimated heritabilities of feather eating, general locomotor activity and feather pecking were 0.36, 0.29 and 0.20, respectively. The genetic correlation between feather pecking and feather eating (general locomotor activity) was 0.17 (0.04). A high genetic correlation of 0.47 was estimated between feather eating and general locomotor activity. The recursive effect from feather eating to feather pecking was λ ̂_(FP,FE)= 0.258, and from general locomotor activity to feather pecking λ ̂_(FP,GLA)= 0.046. These results imply that an increase of feather eating leads to an increased feather pecking behavior and that an increase in general locomotor activity results in a higher feather pecking value. The objective of chapter four was to perform a quantitative genetic analysis and to map signatures of selection in two divergent laying hen lines selected for feather pecking behaviour. In the selection experiment, lines were selected for low or high feather pecking for 11 generations. Pedigree and phenotypic data were available for the last six generations of both lines for the statistical analysis with a standard mixed linear model and a Poisson model. The mixed linear model failed to analyse the low feather pecker data because of the large number of 0s in the observation vector. The Poisson model fitted the data well and revealed a small but continuous genetic trend in both lines. From the 11th generation 75 birds, 41 high feather peckers and 34 low feather peckers were genotyped using the Illumina 60K chicken Infinium iSelect chip. An FST-based approach was used to map selection signature. We detected 17 genome-wide significant SNPs with a FST-value of 1, i.e. alleles were divergently fixed in the two lines, which are mostly located on chromosome 3 and 4, and a number of additional significant SNPs with a p-value of ≤ 5x10-4 and ≤ 5x10-5, respectively. Based on the assumption that selection affects several consecutive SNPs, 13 clusters were identified. In chapter five, we used the data from the large F2-cross experiment to perform a genome-wide association study for feather pecking and aggressive pecking behaviour, to combine the results of this GWAS with the results from the selection experiment (chapter four) in a meta-analysis, and to link the results to those obtained from a differential gene expression study. 817 F2-hens were genotyped with the Illumina 60K chicken Infinium iSelect chip. We used single marker association analysis and a Poisson model. We detected four genome-wide significant SNPs for aggressive pecking delivered, but none for feather pecking and aggressive pecking received. However, a number of significant SNPs at p≤5x10-5 were mapped for feather pecking and aggressive pecking received. In the meta analysis we identified nine genome-wide significant SNPs for feather pecking delivered, which were localized in chromosomal clusters (3 Mb). A previously conducted differential gene expression analysis provided eight significantly differential expressed genes within the feather pecking associated chromosomal clusters. The thesis ends with a general discussion

Utilização do Programa Farmácia Popular do Brasil por idosos

OBJETIVO Avaliar a prevalência e os fatores associados à utilização do Programa Farmácia Popular do Brasil – modelo expansão entre idosos e os motivos de não utilização. MÉTODOS Neste estudo transversal de base populacional, realizado na zona urbana de Pelotas, RS, foram avaliados 1.305 idosos (60 anos ou mais) que utilizaram medicamentos nos últimos 15 dias. Como variáveis independentes foram caracterizados fatores socioeconômicos, nível econômico, renda familiar em salários mínimos, escolaridade em anos de estudo e status ocupacional. As variáveis demográficas foram sexo, idade, situação conjugal e cor da pele autorreferida. Para análise dos fatores associados à utilização do PFPB-E, utilizou-se regressão de Poisson. RESULTADOS A prevalência de utilização do programa foi de 57,0% e a de conhecimento foi de 87,0%. Nos indivíduos com 80 anos ou mais, a utilização do programa foi de 41,0%. Quanto à origem das prescrições utilizadas pelos idosos, 46,0% eram oriundas do SUS. Os principais motivos para não utilização foram: dificuldade em conseguir receita, falta do medicamento, desconhecimento sobre os medicamentos ofertados e sobre o programa. Maior idade, menor renda, ter doença crônica e usar quatro ou mais medicamentos estiveram associados à utilização. CONCLUSÕES É preciso ampliar o conhecimento e a utilização do Programa Farmácia Popular do Brasil, especialmente entre os mais idosos, e melhorar a divulgação da lista de medicamentos do programa aos usuários e aos médicos. Dessa forma, será possível reduzir gastos com medicamentos de uso contínuo, que são especialmente importantes para essa população.OBJECTIVE To assess the prevalence and factors associated with the use of the expanded Brazilian People’s Pharmacy Program among older adults and the reasons for not using it. METHODS In this population-based cross-sectional study conducted in the urban area of Pelotas, RS, Southern Brazil, we evaluated 1,305 older adults (aged 60 years or over) who had used medication in the last 15 days. Independent variables were socioeconomic factors, economic status, household income in minimum wages, educational attainment in years of schooling and occupational status. Demographic variables were sex, age, marital status, and self-reported skin color/race. Poisson regression was employed to analyze the factors associated with the use of the program. RESULTS The prevalence of use was 57.0% whilst the prevalence of knowledge of the program was 87.0%. In individuals aged 80 years or over, use of the program was 41.0%. As to the origin of the prescriptions used by older adults, 46.0% were from the Brazilian Unified Health System. The main reasons for not using the program were: difficulty in getting prescriptions, medication shortage, and ignorance about the medications offered and about the program. Higher age, lower income, presence of chronic diseases, and use of four or more medications were associated with use of the program. CONCLUSIONS It is necessary to expand the knowledge and use of the Brazilian People’s Pharmacy Program, especially among older adults, and to improve the dissemination of its list of medications to users and physicians. Thus it will be possible to reduce spending on long-term medications, which are especially important for this population

Dissociating refreshing and elaboration and their impacts on memory

Maintenance of information in working memory (WM) is assumed to rely on refreshing and elaboration, but clear mechanistic descriptions of these cognitive processes are lacking, and it is unclear whether they are simply two labels for the same process. This fMRI study investigated the extent to which refreshing, elaboration, and repeating of items in WM are distinct neural processes with dissociable behavioral outcomes in WM and long-term memory (LTM). Multivariate pattern analyses of fMRI data revealed differentiable neural signatures for these processes, which we also replicated in an independent sample of older adults. In some cases, the degree of neural separation within an individual predicted their memory performance. Elaboration improved LTM, but not WM, and this benefit increased as its neural signature became more distinct from repetition. Refreshing had no impact on LTM, but did improve WM, although the neural discrimination of this process was not predictive of the degree of improvement. These results demonstrate that refreshing and elaboration are separate processes that differently contribute to memory performance

Potentially inappropriate medications among older adults in Pelotas, Southern Brazil

OBJECTIVE To assess the use of potentially inappropriate medications among older adults. METHODS This is a population-based cross-sectional study with 1,451 older individuals aged 60 years or more in the city of Pelotas, State of Rio Grande do Sul, Brazil, in 2014. We have investigated the use of medications in the last 15 days. Using the Beers criteria (2012), we have verified the use of potentially inappropriate medications and their relationship with socioeconomic and demographic variables, polypharmacy, self-medication, and burden of disease. RESULTS Among the 5,700 medications used, 5,651 could be assessed as to being inappropriate. Of these, 937 were potentially inappropriate for the older adults according to the 2012 Beers criteria (16.6%). Approximately 42.4% of the older adults studied used at least one medication considered as potentially inappropriate. The group of medications for the nervous system accounted for 48.9% of the total of the potentially inappropriate medications. In the adjusted analysis, the variables female, advanced age, white race, low educational level, polypharmacy, self-medication, and burden of disease were associated with the use of potentially inappropriate medications. CONCLUSIONS It is important to known the possible consequences of the use of medication among older adults. Special attention should be given to the older adults who use polypharmacy. Specific lists should be created with more appropriate medications for the older population in the National Essential Medicine List.OBJETIVO Avaliar o uso de medicamentos potencialmente inadequados entre idosos. MÉTODOS Estudo transversal de base populacional com 1.451 idosos com 60 anos ou mais em Pelotas, RS, em 2014. Investigou-se o uso de medicamentos nos últimos 15 dias. Utilizando os critérios de Beers (2012), verificou-se a potencial inadequação dos medicamentos e sua relação com variáveis socioeconômicas e demográficas, polifarmácia, automedicação e carga de doença. RESULTADOS Dentre os 5.700 medicamentos utilizados, 5.651 puderam ser avaliados quanto à inadequação. Destes, 937 eram potencialmente inadequados para idosos segundo os critérios de Beers de 2012 (16,6%). Cerca de 42,4% dos idosos usaram no mínimo um medicamento considerado potencialmente inapropriado. O grupo de medicamentos para o sistema nervoso correspondeu a 48,9% do total de medicamentos potencialmente inadequados. Na análise ajustada, as variáveis sexo feminino, idade avançada, cor da pele branca, baixa escolaridade, polifarmácia, automedicação e carga de doença mostraram-se associadas ao uso de medicamentos potencialmente inadequados. CONCLUSÕES É importante que sejam bem conhecidas as possíveis consequências do uso de medicamentos entre idosos. Atenção especial deve ser dada aos idosos que fazem uso de polifarmácia. É necessário existir listas específicas com medicamentos mais adequados para uso em idosos na Relação Nacional de Medicamentos Essenciais

Root and crown rot pathogens found on dry beans grown in Mozambique

Dry edible beans are a vital food source in Mozambique, East Africa—one that alleviates hunger and malnutrition and adds value to the economy. In recent years, root/crown rot (RCR) pathogens have emerged as limiting constraints in dry bean production. Not much has been characterized concerning the causal agents of RCR in Mozambique. The purpose of this study was to identify the primary pathogen(s) associated with RCR dry bean samples collected at breeder nursery sites and farmer fields in Mozambique using molecular sequencing and culture-based methods. Sequencing revealed, not surprisingly, an increased diversity of fungal/oomycete operational taxonomic units when compared to culture-based methods of diversity. Species of Fusarium, mainly F. oxysporum, were the dominant taxa detected in RCR dry beans through sequencing the ITS rDNA region and partial EF-1α gene. Collectively, 333 fungi and/or Oomycetes were isolated in culture during the 2014–2015 growing seasons and tested for pathogenicity on healthy bean seedlings. Fusarium species were identified by both morphological and molecular characters. At least 60% of the isolates inoculated on common bean were recognized as potentially pathogenic. From both isolation frequency and pathogenicity testing, F. oxysporum and related species play an important role in the bean RCR complex. We found similar results from dry beans grown in the two main bean-growing regions of Mozambique. These findings will allow breeders to screen for resistance to F. oxysporum in greenhouse grown bean plants as well as within field grown bean cultivars

Efecto de la técnica de acodo en Dracaena marginata, sobre la calidad de las raíces

Se comparó el efecto del tiempo transcurrido desde la dilución de la hormona AIB y la forma de conservación de la hormona de enraizamiento AIB, y su relación con la forma de trabajo de cuatro acodadores (operarios que realizan los acodos) sobre la exportabilidad y la calidad de las raíces de acodos en cañas de Dracaena marginata de 4" y 6". Se utilizó un diseño irrestricto aleatorio con un arreglo factoria l4x3, y como unidad experimental cuatro minutos de trabajo. Se evaluaron tres variables en cada acodo: exportabilidad, ausencia de doble fila de raíces y largo de éstas, para lo cual se utilizaron modelos de regresión logística. Se encontraron interacciones entre el trabajo del acodador y el efecto de envejecimiento de la hormona para las tres variables modeladas, las cuales indican que uniformar el procedimiento con el que se realiza el acodo puede llevar a una mayor calidad y a aumentar la probabilidad de que cada caña sea exportable

Iron salt supplementation during gestation and gestational diabetes mellitus

OBJETIVE: To evaluate the association between the use of iron salts during the first two trimesters of gestation in non-anemic women and the development of gestational diabetes mellitus. METHODS: The study used maternal data from the 2015 Pelotas Birth Cohort. All non-anemic women at the 24th week of gestation (n = 2,463) were eligible for this study. Gestational diabetes mellitus was self-reported by women. Crude and adjusted logistic regression were performed considering level of significance = 0.05. RESULTS: Among the women studied, 69.7% were exposed to prophylactic iron supplementation in the first two trimesters of gestation. The prevalence of gestational diabetes mellitus among those exposed was 8.7% (95%CI: 7.4–10.1) and 9.3% (95%CI: 7.4–11.6) among those who were not exposed. Iron supplementation was not associated with increased risk of gestational diabetes mellitus in crude (OR = 0.9; 95%CI: 0,7–1,3) and adjusted analysis (OR = 1.1; 95%CI :0,8–1,6). CONCLUSIONS: The results suggest that routine iron use in non-anemic pregnant women does not increase the risk of developing gestational diabetes. This evidence supports the existing national and international guidelines, in which prophylactic iron supplementation is recommended for all pregnant women as soon as they initiate antenatal care in order to prevent iron deficiency anemia

Medication use among pregnant women from the 2015 Pelotas (Brazil) birth cohort study

Background: Medication use during pregnancy is a common practice that has been increasing in recent years. The aim of this study is to describe medication use among pregnant women from the 2015 Pelotas (Brazil) Birth Cohort Study. Methods: This paper relies on a population-based cohort study including 4270 women. Participants completed a questionnaire about the antenatal period, including information about medication use. We performed descriptive analyses of the sample and the medications used and adjusted analyses for the use of medications and self-medication. Results: The prevalence of medication use was 92.5% (95% CI 91.7–93.3), excluding iron salts, folic acid, vitamins, and other minerals. The prevalence of self-medication was 27.7% (95% CI 26.3–29.1). In the adjusted analysis, women who had three or more health problems during pregnancy demonstrated higher use of medicines. Self-medication was higher in lower income groups and among smokers and multiparous women (three pregnancies or more). Acetaminophen, scopolamine, and dimenhydrinate were the medications most commonly used. Conclusions: This study describes the pattern of drug use among pregnant women in a population-based cohort study, with a high prevalence of self-medication. Greater awareness of the risks of self-medication during pregnancy is required, focusing on groups more prone to this practice, as well as ensuring qualified multidisciplinary prenatal care

Spring Commencement, 2017

Program for the One Hundred Eightieth Commencement of Marshall University

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