Extended hydrogen photoproduction by nitrogen-fixing cyanobacteria

Cyanobacteria are the only prokaryotic organisms performing oxygenic photosynthesis. They comprise a diverse and versatile group of organisms in aquatic and terrestrial environments. Increasing genomic and proteomic data launches wide possibilities for their employment in various biotechnical applications. For example, cyanobacteria can use solar energy to produce H2. There are three different enzymes that are directly involved in cyanobacterial H2 metabolism: nitrogenase (nif) which produces hydrogen as a byproduct in nitrogen fixation; bidirectional hydrogenase (hox) which functions both in uptake and in production of H2; and uptake hydrogenase (hup) which recycles the H2 produced by nitrogenase back for the utilization of the cell. Cyanobacterial strains from University of Helsinki Cyanobacteria Collection (UHCC), isolated from the Baltic Sea and Finnish lakes were screened for efficient H2 producers. Screening about 400 strains revealed several promising candidates producing similar amounts of H2 (during light) as the ΔhupL mutant of Anabaena PCC 7120, which is specifically engineered to produce higher amounts of H2 by the interruption of uptake hydrogenase. The optimal environmental conditions for H2 photoproduction were significantly different between various cyanobacterial strains. All suitable strains revealed during screening were N2-fixing, filamentous and heterocystous. The top ten H2 producers were characterized for the presence and activity of the enzymes involved in H2 metabolism. They all possess the genes encoding the conventional nitrogenase (nifHDK1). However, the high H2 photoproduction rates of these strains were shown not to be directly associated with the maximum capacities of highly active nitrogenase or bidirectional hydrogenase. Most of the good producers possessed a highly active uptake hydrogenase, which has been considered as an obstacle for efficient H2 production. Among the newly revealed best H2 producing strains, Calothrix 336/3 was chosen for further, detailed characterization. Comparative analysis of the structure of the nif and hup operons encoding the nitrogenase and uptake hydrogenase enzymes respectively showed minor differences between Calothrix 336/3 and other N2-fixing model cyanobacteria. Calothrix 336/3 is a filamentous, N2-fixing cyanobacterium with ellipsoidal, terminal heterocysts. A common feature of Calothrix 336/3 is that the cells readily adhere to substrates. To make use of this feature, and to additionally improve H2 photoproduction capacity of the Calothrix 336/3 strain, an immobilization technique was applied. The effects of immobilization within thin alginate films were evaluated by examining the photoproduction of H2 of immobilized Calothrix 336/3 in comparison to model strains, the Anabaena PCC 7120 and its ΔhupL mutant. In order to achieve optimal H2 photoproduction, cells were kept under nitrogen starved conditions (Ar atmosphere) to ensure the selective function of nitrogenase in reducing protons to H2. For extended H2 photoproduction, cells require CO2 for maintenance of photosynthetic activity and recovery cycles to fix N2. Application of regular H2 production and recovery cycles, Ar or air atmospheres respectively, resulted in prolongation of H2 photoproduction in both Calothrix 336/3 and the ΔhupL mutant of Anabaena PCC 7120. However, recovery cycles, consisting of air supplemented with CO2, induced a strong C/N unbalance in the ΔhupL mutant leading to a decrease in photosynthetic activity, although total H2 yield was still higher compared to the wild-type strain. My findings provide information about the diversity of cyanobacterial H2 capacities and mechanisms and provide knowledge of the possibilities of further enhancing cyanobacterial H2 production.Syanobakteerit ovat ainoita prokaryoottisia eliöitä, jotka kykenevät fotosynteesiin. Syanobakteerit ovat monimuotoisia ja niitä löytyy lähes jokaisesta elinympäristöstä. Lisääntyvä tieto eri lajien genomeista ja niiden ilmentymisestä avaa laajoja mahdollisuuksia syanobakteerien biotekniseen soveltamiseen. Syanobakteerit pystyvät muun muassa valoenergiaa hyväksikäyttäen tuottamaan vetyä. Niillä on kolme entsyymiä, jotka ovat suoraan yhteydessä vetymetaboliaan: nitrogenaasi (nif) tuottaa vetyä typen sitomisen sivutuotteena; kaksisuuntainen hydrogenaasi (hox) sekä kuluttaa että tuottaa vetyä; ja lisäksi vetyä kuluttava hydrogenaasi (hup) kierrättää nitrogenaasin tuottaman vedyn takaisin solun energiakäyttöön. Tässä tutkimuksessa seulottiin Itämerestä ja Suomen järvistä eristettyjen syanobakteerien (Helsingin yliopiston kantakokoelma, UHCC) joukosta hyvin vetyä tuottavia kantoja. Neljän sadan seulontaan valitun kannan joukosta löytyi muutama villityypin syanobakteerikanta, joiden vedyn tuotanto on samalla tasolla kuin geenitekniikan avulla muokattujen kantojen tehostettu vedyntuottokyky – kuten Anabaena 7120 -kannan hup poistogeeninen mutantti (ΔhupL). Ihanteelliset olosuhteet vedyn valotuotannolle vaihtelevat eri kantojen välillä. Kaikki seulonnassa valikoituneet kannat ovat ilmakehän typpeä sitovia, rihmamaisia ja heterokystejä muodostavia. Vedyn tuotantoon osallistuvat kartoitettiin kymmeneltä parhaalta kannalta, joilta kaikilta löydettiin tavallista nitrogenaasia (nifHDK1) koodaavat geenit. Valittujen kantojen korkea vedyn tuotantokyky ei kuitenkaan osoittautunut olevan suoraa seurausta nitrogenaasin tai kaksisuuntaisen hydrogenaasin korkeasta aktiivisuudesta. Suurimmalla osalla parhaista vedyntuottajista osoittautui olevan hyvin aktiivinen vetyä kuluttava hydrogenaasi, jonka on ajateltu olevan este tehokkaalle vedyn tuotannolle. Kymmenen parhaan vedyntuottajakannan joukosta valittiin Calothrix 336/3 tarkempaan tarkasteluun. Nitrogenaasin ja vetyä kuluttavan hydrogenaasin nif ja hup operonien vertaileva analyysi paljasti pieniä poikkeamia Calothrix 336/3:n ja muiden typpeä sitovien mallikantojen välillä. Calothrix 336/3 on rihmamainen, typpeä sitova syanobakteeri, jolla on soikion muotoiset, rihmojen päissä olevat heterokystit. Calothrix 336/3:lla on kyky tarttua kiinni erilaisiin pintoihin ja kasvaa niiden pinnalla. Tätä ominaisuutta ja immobilisointi-tekniikkaa hyödyntämällä pystyttiin edelleen parantamaan vedyn valotuotantokapasiteettia. Alginaatilla immobilisointia vedyn valotuotantosysteeminä tutkittiin Calothrix 336/3:lla ja verrattiin sitä Anabaena 7120:een ja sen ΔhupL-mutanttiin samassa systeemissä. Ihanteellisen vedyn valotuotannon saavuttamiseksi, soluja pidettiin typpivapaissa olosuhteissa (Ar kaasufaasina), näin varmistaen nitrogenaasin toiminnan protonien pelkistämisessä vedyksi. Lisäksi syanobakteerisolut tarvitsevat pitkäaikaiseen vedyn valotuotantoon myös hiilidioksidia fotosynteettisen aktiivisuuden säilyttämiseksi sekä palautumissyklit mahdollistaakseen typen sitomisen. Säännöllisten vedyn valotuotantojaksojen ja palautumissyklien avulla, joissa Ar tai ilma toimivat kaasufaaseina, saatiin sekä Calothrix 336/3:n ja Anabaena 7120 ΔhupL-mutantin vedyn valotuotantoa huomattavasti pitkitettyä. On huomionarvoista, että ilman ja lisätyn hiilidioksidin toimiessa palautumissyklissä, ΔhupL-mutantin fotosynteettinen aktiivisuus väheni C/N epätasapainon johdosta, vaikka sen vedyn tuotto olikin parempi kuin vastaavan villityypin. Tutkimukseni lisää tietoa syanobakteerien vedyntuotannon moninaisuudesta ja mekanismeista, sekä lisää ymmärrystä syanobakteerien vedyn tuotannon lisäämiseksi tulevaisuudessa.Siirretty Doriast

Learning from and with Customers with Social Media: A Model for Social Customer Learning

Social media can enable and significantly increase the collaboration andlearning from customers in various ways, for instance by novel social waysof providing and receiving feedback from new products and concepts. Wehave created a model that can support managers and researchers to betteranalyse and understand the possibilities of social media approaches especiallyfrom the business-to-business (B2B) customer interface standpoint. Weused the model to analyse found various types of business-to-business relatedsocial media approaches to create new understanding of the scarcelyresearched field of social media in the customer learning and the customerinterface of B2B innovation

Ethical climate and nurse competence - newly graduated nurses' perceptions

Background: Nursing practice takes place in a social framework, in which environmental elements and interpersonal relations interact. Ethical climate of the work unit is an important element affecting nurses' professional and ethical practice. Nevertheless, whatever the environmental circumstances, nurses are expected to be professionally competent providing high-quality care ethically and clinically. Aim: This study examined newly graduated nurses' perception of the ethical climate of their work environment and its association with their self-assessed professional competence, turnover intentions and job satisfaction. Method: Descriptive, cross-sectional, correlational research design was applied. Participants consisted of 318 newly graduated nurses. Data were collected electronically and analysed statistically. Ethical considerations: Ethical approval and permissions to use instruments and conduct the study were obtained according to required procedures. Data were rendered anonymous to protect participant confidentiality. Completing the questionnaire was interpreted as consent to participate. Findings: Nurses' overall perception of the ethical climate was positive. More positive perceptions related to peers, patients and physicians, and less positive to hospitals and managers. Strong associations were found between perceived ethical climate and self-assessed competence, turnover intentions in terms of changing job, and job satisfaction in terms of quality of care. Nurses at a higher competence level with positive views of job satisfaction and low turnover intentions perceived the climate significantly more positively. Conclusion: Nursing management responsible for and having the power to implement changes should understand their contribution in ethical leadership, as well as the multidimensional nature of nurses' work environment and the interaction between work-related factors in planning developmental measures. Future research should focus on issues in nurse managers' ethical leadership in creating ethical work environments. There is also a need for knowledge of newly graduated nurses' views of factors which act as enhancers or barriers to positive ethical climates to develop. Interventions, continuing education courses, and discussions designed to promote positive ethical climates should be developed for managers, nurses, and multi-professional teams.Peer reviewe

: Normobaric hypoxia training in military aviation and subsequent hypoxia symptom recognition

ABSTRACT Altitude hypoxia episodes are increasingly common in military aviation. Hypoxia training is man datory for fighter pilots, but evidence-based data on the effects of training are scarce. The pur pose of this study was to validate the normobaric hypoxia (NH) training effect. Data were collected from 89 pilots from the Finnish Air Force (FINAF). This survey was conducted in a tac tical F/A-18C Hornet simulator in two sessions under normobaric conditions, in which the pilots performed flight missions and breathed 21% oxygen (O2) in nitrogen (N2), and blinded to the pilot, the breathing gas was changed to a hypoxic mixture containing either 8, 7 or 6% O2 in N2. The time taken to notice hypoxia symptoms and peripheral capillary O2 saturation was measured. A mean of 2.4 years after the initial training, pilots recognised their hypoxic symp toms 18 s quicker with 8% O2 mixture, 20 s quicker with 7% O2 and 10 s quicker with 6% O2. Our data indicate that NH training in a flight simulator helps pilots to recognise hypoxia symp toms earlier, and may, thus, enhance flight safety. Practitioner Summary: We show that hypoxia training enhances pilots’ ability to recognise symptoms of acute normobaric hypoxic exposure up to 2.4 years after an initial NH training ses sion. Based on these data, refreshment NH training is nowadays mandatory every 3 years in the FINAF as opposed to the North Atlantic Treaty Organisation (NATO) Standardisation Agreement (STANAG) requirement of 5-year intervals between hypoxia trainings. Abbreviations: O2: oxygen; TUC; time of usefull consciousness; SpO2: peripheral capillary oxy gen saturation; NATO: North Atlantic Treaty Organization; STANAG: stanrdization agreement; HH: hypobaric hypoxia; NH: normobaric hypoxia; FINAF: finnish air force; N2: nitrogen; ECG: electro cardiogra

New evidence on the association of occupation with amyotrophic lateral sclerosis : A register-based case-control study in Finland

ObjectivesAmyotrophic lateral sclerosis (ALS) is a serious neurodegenerative disease that usually leads to death within a few years from diagnosis. The risk factors for ALS are still largely unknown. However, it is assumed that environmental factors play a role in disease onset. Occupation is suggested as a potential risk factor, but findings are inconsistent. The aim of this study was to assess the association of occupation with ALS in Finland. Register data were used to avoid recall bias and to obtain a large enough sample to detect the potential associations. MethodsThis case-control study included ALS cases that occurred between 1980 and 2015 in Finland (n = 4,781). ALS cases were identified from the causes of death register. For each ALS case, six controls were selected matched for sex and birth-year. The date of death of the ALS case was set as index date. Information on occupation was obtained from Statistics Finland for all subjects. The focus was on the longest-held occupation on 2-digit level (70 groups). The association of occupation with ALS was analyzed using conditional logistic regression. ResultsCompared to "clerical work and other office work," the risk of ALS was increased in "packing and wrapping work" (OR 1.53, 95% CI 1.08-2.17), "laundering, dry cleaning and pressing work" (OR 1.83, 95% CI 1.08-3.08), and "travel service work" (OR 8.75, CI 2.76-27.74). A decreased risk was found in "planning, administrative and research work in the technical fields" (OR 0.69, 95% CI 0.48-0.98). Of the significant associations identified, only "travel service work" was significant after FDR multiple testing correction. ConclusionsThis study identified occupations in which the risk of ALS was increased. Further studies are needed to pinpoint the potential exposures in these occupations that may trigger the disease.Peer reviewe

A New Method for Combined Hyperventilation and Hypoxia Training in a Tactical Fighter Simulator

Physiological episodes are an issue in military aviation. Some non-pressure-related in-flight symptoms are proved to be due to hyperventilation rather than hypoxia. The aim of this study was to validate a new training method provoking hyperventilation during normobaric hypoxia (NH) training in an F/A-18 Hornet simulator. METHODS: In a double-blind setting, 26 fighter pilots from the Finnish Air Force performed 2 setups in a WTSAT simulator in randomized order with full flight gear. Without the pilot's knowledge, 6% O2 in nitrogen or 6% O2 + 4% CO2 in nitrogen was turned on. Ventilation (VE) was measured before, during, and after hypoxia. SpO2 and ECG were monitored and symptoms documented. The subjects performed a tactical identification flight until they recognized symptoms of hypoxia. Thereafter, they performed hypoxia emergency procedures with 100% O2 and returned to the base with a GPS malfunction and executed an instrument landing system (ILS) approach with the waterline HUD mode evaluated by the flight instructor on a scale of 1 to 5. RESULTS: Ventilation increased during normobaric hypoxia (NH) from 12 L · min−1 to 19 L · min−1 at SpO2 75% with 6% O2, and from 12 L · min−1 to 26 L · min−1 at SpO2 77% with 6% O2 + 4% CO2. ILS flight performance was similar 10 min after combined hyperventilation and hypoxia (3.1 with 6% O2 + 4% CO2 and 3.2 with 6% O2). No adverse effects were reported during the 24-h follow-up. DISCUSSION: Hyperventilation-provoking normobaric hypoxia training is a new and well-tolerated method to meet NATO Standardization Agreement hypoxia training requirements

Bone as a Possible Target of Chemical Toxicity of Natural Uranium in Drinking Water

Uranium accumulates in bone, affects bone metabolism in laboratory animals, and when ingested in drinking water increases urinary excretion of calcium and phosphate, important components in the bone structure. However, little is known about bone effects of ingested natural uranium in humans. We studied 146 men and 142 women 26–83 years of age who for an average of 13 years had used drinking water originating from wells drilled in bedrock, in areas with naturally high uranium content. Biochemical indicators of bone formation were serum osteocalcin and amino-terminal propeptide of type I procollagen, and a marker for bone resorption was serum type I collagen carboxy-terminal telopeptide (CTx). The primary measure of uranium exposure was uranium concentration in drinking water, with additional information on uranium intake and uranium concentration in urine. The data were analyzed separately for men and women with robust regression (which suppresses contributions of potential influential observations) models with adjustment for age, smoking, and estrogen use. The median uranium concentration in drinking water was 27 μg/L (interquartile range, 6–116 μg/L). The median of daily uranium intake was 36 μg (7–207 μg) and of cumulative intake 0.12 g (0.02–0.66 g). There was some suggestion that elevation of CTx (p = 0.05) as well as osteocalcin (p = 0.19) could be associated with increased uranium exposure (uranium in water and intakes) in men, but no similar relationship was found in women. Accordingly, bone may be a target of chemical toxicity of uranium in humans, and more detailed evaluation of bone effects of natural uranium is warranted

Congruence between perceived and theoretical knowledge before and after an internet-based continuing education program about venous leg ulcer nursing care

Background: Previous research has revealed nurses' knowledge gaps in venous leg ulcer (VLU) nursing care, and continuing education is needed. The closer nurses' perceived knowledge is to their evidence-based theoretical knowledge, the better possibilities they have to conduct evidence-based VLU nursing care. Objectives: To assess the congruence between nurses' perceived and theoretical knowledge about VLU nursing care before and after an internet-based education about VLU nursing care (eVLU). Design: Quasi-experimental study with intervention and comparison groups and pre- and post-measurements. Setting: Home health care in two Finnish municipalities. Participants: Nurses (n = 946) working in home health care were invited to participate. In the intervention group, 239 nurses and 229 nurses in the comparison group met the inclusion criteria, and they were all recruited to the study. Method: Nurses were divided into intervention and comparison groups with lottery between the municipalities. Nurses in both groups took care of patients with VLU according to their organizations' instructions. In addition to this, nurses in the intervention group received a 6-week eVLU while those in the comparison group did not. Data were collected with a questionnaire about perceived and theoretical knowledge before education, at six weeks, and at 10 weeks. The percentages of congruence were calculated at every measurement point, and the McNemar test was used to detect statistical significance of changes between measurements. Results: The increase of congruence was more often statistically significant in the intervention group than in the comparison group. Conclusion: The results support the hypothesis that the congruence between perceived and theoretical knowledge will be higher among nurses receiving eVLU. Because of the low participation and drop-outs, the results should be interpreted with caution.Peer reviewe

Normobaric hypoxia training in military aviation and subsequent hypoxia symptom recognition

Altitude hypoxia episodes are increasingly common in military aviation. Hypoxia training is mandatory for fighter pilots, but evidence-based data on the effects of training are scarce. The purpose of this study was to validate the normobaric hypoxia (NH) training effect. Data were collected from 89 pilots from the Finnish Air Force (FINAF). This survey was conducted in a tactical F/A-18C Hornet simulator in two sessions under normobaric conditions, in which the pilots performed flight missions and breathed 21% oxygen (O2) in nitrogen (N2), and blinded to the pilot, the breathing gas was changed to a hypoxic mixture containing either 8, 7 or 6% O2 in N2. The time taken to notice hypoxia symptoms and peripheral capillary O2 saturation was measured. A mean of 2.4 years after the initial training, pilots recognised their hypoxic symptoms 18 s quicker with 8% O2 mixture, 20 s quicker with 7% O2 and 10 s quicker with 6% O2. Our data indicate that NH training in a flight simulator helps pilots to recognise hypoxia symptoms earlier, and may, thus, enhance flight safety. Practitioner Summary: We show that hypoxia training enhances pilots’ ability to recognise symptoms of acute normobaric hypoxic exposure up to 2.4 years after an initial NH training session. Based on these data, refreshment NH training is nowadays mandatory every 3 years in the FINAF as opposed to the North Atlantic Treaty Organisation (NATO) Standardisation Agreement (STANAG) requirement of 5-year intervals between hypoxia trainings. Abbreviations: O2: oxygen; TUC; time of usefull consciousness; SpO2: peripheral capillary oxygen saturation; NATO: North Atlantic Treaty Organization; STANAG: stanrdization agreement; HH: hypobaric hypoxia; NH: normobaric hypoxia; FINAF: finnish air force; N2: nitrogen; ECG: electrocardiogram; CI: confidence interval; SD: standard deviation.publishedVersionPeer reviewe