Hybrid solar cells based on thin-film silicon and P3HT

International audienceHybrid concepts based on a nanoscale combination of organic and inorganic semiconductors are a promising way to enhance the cost efficiency of solar cells through a better use of the solar spectrum, a higher aspect ratio of the interface, and the good processability of polymers. A new type of solar cells has been investigated. It is based on a heterojunction between regio-regular poly(3-hexylthiophene) as an organic electron donor and silicon as an inorganic electron acceptor. In a first step towards nanostructured devices, cells made of flat thin films of these materials have been studied as a model case of the heterojunction. The materials were characterized through ellipsometry and absorption spectroscopy. The devices were studied by means of their spectral response and their I-V characteristics. By combining these results, the contribution of each layer and the mechanisms of photocurrent generation are explained. The best cells to-date show a power conversion efficiency of 1.6% under AM 1.5 illumination, with a Voc of 0.704 V and a Jsc of 4.22 mA/cm2

The Fungal Cell Wall : Structure, Biosynthesis, and Function

N.G. is funded by the Wellcome Trust via a senior investigator award and a strategic award and by the MRC Centre for Medical Mycology. C.M. acknowledges the support of the Wellcome Trust and the MRC. N.G. and C.M. are part of the MRC Centre for Medical Mycology. J.P.L. acknowledges support from ANR, Aviesan, and FRM.Peer reviewedPublisher PD

Reduction of indole-3-acetic acid methyltransferase activity compensates for high-temperature male sterility in Arabidopsis

High temperature is a general stress factor that causes a decrease in crop yield. It has been shown that auxin application reduces the male sterility caused by exposure to higher temperatures. However, widespread application of a hormone with vast effects on plant physiology may be discouraged in many cases. Therfore, the generation of new plant varieties that locally enhance auxin in reproductive organs may represent an alternative strategy. We have explored the possibility of increasing indoleacetic acid (IAA) in ovaries by reducing IAA METHYLTRANSFERASE1 (IAMT1) activity in Arabidopsis thaliana. The iamt1 mutant showed increased auxin signaling in funiculi, which correlated with a higher growth rate of wild-type pollen in contact with mutant ovaries and premature ovule fertilization. While the production of seeds per fruit was similar in the wild type and the mutant at 20°C, exposure to 29°C caused a more severe decrease in fertility in the wild type than in the mutant. Loss of IAMT1 activity was also associated with to the production of more nodes after flowering and higher tolerance of the shoot apical meristem to higher temperatures. As a consequence, the productivity of the iamt1 mutant under higher temperatures was more than double of that of the wild type, with almost no apparent trade-off

Afaattisten henkilöiden ja heidän läheistensä subjektiivinen arvio kuorolauluintervention hyödyistä

Tavoitteet. Tutkimuksen tavoitteena oli tarkastella uudenlaisen afasian kuntoutukseen suunnatun kuorolauluintervention subjektiivisesti koettua hyötyä. Interventio oli osa Helsingin yliopiston Kognitiivisen aivotutkimuksen yksikön Laulun sanoin -hanketta ja se koostui kuorolaulusta, ryhmämuotoisesta MIT (melodinen intonaatioterapia) -kuntoutuksesta sekä laulun harjoittelusta tablettitietokoneella. Interventioon osallistui afasiaa sairastavia henkilöitä sekä heidän läheisiään. Aiemmissa tutkimuksissa on havaittu, että musiikilla ja laululla voi olla kuntoutuksellisia vaikutuksia muun muassa kielellisiin toimintoihin. Afasian kuntoutuksessa on eniten tutkittu MIT-menetelmää, mutta myös uusia musiikkia sisältäviä kuntoutusmuotoja kehitetään aktiivisesti. Subjektiivisesti koettua kuntoutuksesta saatua hyötyä ei ole afasian osalta erityisesti tutkittu, vaikka oman kokemuksen tiedetään vaikuttavan kuntoutuk- sen lopputulokseen. Tässä tutkimuksessa tarkastellaan, minkälainen subjektiivinen arvio afaattisilla henkilöillä ja heidän läheisillään oli interventiosta. Lisäksi tarkastellaan, oliko afasian vaikeusasteella, harjoittelumäärällä tai demografisilla tai kliinisillä taustatiedoilla yhteyttä koettuun hyötyyn sekä erosivatko afaattisten henkilöiden ja läheisten kokemukset toisistaan. Menetelmät. Aineiston muodosti osallistujien intervention jälkeen täyttämät kyselylomakkeet subjektiivisista kokemuksista, interventiojakson aikana toteutuneet harjoittelumäärät sekä osallistujien demografiset ja kliiniset taustatiedot. Kyselylomakkeeseen vastasi 23 afaattista henkilöä sekä 11 läheistä. Aineistoa analysoitiin tilastollisesti Friedmanin testillä, Mann–Whitney U-testillä, Spearmanin järjestyskorrelaatioanalyysilla, Wilcoxonin merkittyjen sijalukujen testillä sekä yhden otoksen t-testillä. Avointen kysymysten vastauksia analysoitiin tyypittelemällä vastauksia teemoittain ja laskemalla esiintymisfrekvenssejä. Tulokset ja johtopäätökset. Afaattiset henkilöt kokivat intervention hyödylliseksi ja myös läheiset kokivat, että interventio oli afaattisille henkilöille hyödyllinen. Afaattisten henkilöiden ja läheisten kokemukset intervention hyödyllisyydestä eivät eronneet toisistaan, eikä harjoittelumäärän, kliinisten tai musiikillisten taustatietojen ja koetun hyödyn välillä havaittu tilastollisesti merkitsevää yhteyttä. Erityisesti mielialan kohoaminen, uusiin ihmisiin tutustuminen ja vertaistuen saaminen nousivat esiin kvalitatiivisissa vastauksissa. Näiden tulosten perusteella voidaan ehdottaa, että ryhmämuotoinen kuoro- laulukuntoutus, jossa on MIT:n elementtejä, vaikuttaa positiivisesti afaattisten henkilöiden mielialaan, sekä heidän itse arvioimana että läheisten arvioimana. Interventiosta voi jatkotutkimuksen avulla ke-hittää afasian ryhmämuotoisen laulukuntoutusmuodon.Målsättningar. Målsättningen med studien var att granska den subjektivt upplevda nyttan av en ny körsångsintervention som är en rehabiliteringsmetod riktad till afatiska personer. Interventionen var en del av Helsingfors universitets Laulun sanoin -projekt vid enheten för kognitiv hjärnforskning och den bestod av körsång, MIT (melodisk intonationsterapi) samt av sångövning med hjälp av tablettdator. I interventionen deltog afatiska personer och deras anhöriga. Tidigare forskning har påvisat att musik och sång kan ha en rehabiliterande verkan på bland annat språkliga funktioner. Inom afasiforskning har man speciellt koncentrerat sig på vilka rehabiliterande effekter MIT-metoden har, men även nya rehabiliteringsmetoder som innehåller musik och sång utvecklas aktivt. Forskning har påvisat att den subjektiva upplevelsen inverkar på rehabiliteringens resultat, men i dagsläget saknas det specifik forskning om hur afatiska personer upplever sin rehabiliteringsprocess. I denna studie granskas de afatiska personernas och deras anhörigas subjektiva upplevelse om körsångsinterventionen. Därtill granskas huruvida afasins svårighetsgrad, mängden övning eller de demografiska eller kliniska bakgrundsuppgifterna hade en koppling till den subjektivt upplevda nyttan. Dessutom granskas om upplevelsen skiljer sig mellan de afatiska personerna och deras anhöriga. Metoder. Materialet bestod av frågeformulärssvar om den subjektivt upplevda nyttan, uppgifter om övningsmängd under interventionen samt deltagarnas demografiska och kliniska bakgrundsuppgifter. 23 afatiska personer och 11 anhöriga fyllde i frågeformuläret. Statistiska analyser gjordes med hjälp av Friedmans test, Mann–Whitney U-test, Spearmans rangkorrelationsanalys, t-test och Wilcoxons rang- summetest. De kvalitativa svaren analyserades genom tematisering och räkning av frekvenser. Resultat och slutsatser. De afatiska personerna upplevde nytta av interventionen och även deras anhö- riga upplevde att afatiska personerna drog nytta av interventionen. De afatiska personernas och anhörigas upplevelser skilde sig inte ifrån varandra. Mängden övning samt de kliniska eller musikaliska bakgrundsuppgifterna korrelerade inte med den subjektivt upplevda nyttan. I de kvalitativa svaren betonade de afatiska personerna att interventionen bidragit positivt till ett gott humör, möjligheten till att träffa nya personer och möjligheten till att få stöd av andra i samma situation. Utifrån dessa resultat kan man konstatera att körsångsrehabilitering i grupp, med element av MIT, kan ha en positiv inverkan på de afatiska personernas sinnesstämning, både enligt dem själva och deras anhöriga. Genom fortsatt forskning kan interventionen utvecklas till en grupprehabiliteringsmetod för personer med afasi

Effect of drought on storage root development and gene expression profile of sweetpotato under greenhouse and field conditions

Greenhouse and field culture systems were used to study the effect of drought conditions on the storage root (SR) formation in \u27Beauregard\u27 sweetpotato (Ipomoea batatas). In the greenhouse culture system, drought was simulated by withholding water for 5 and 10 days after transplanting (DAT) cuttings in dry sand. Control plants received water at planting and every 3 days thereafter. In the field studies, natural drought conditions and selective irrigation were used to impose water deprivation during the critical SR formation period. Greenhouse drought for 5 and 10 DAT reduced the number of SRs by 42% and 66%, respectively, compared with the controls. Field drought resulted in a 49% reduction in U.S. #1 SR yield compared with the irrigated condition. Quantitative real-time polymerase chain reaction (PCR) analysis showed differential expression of a set of sweetpotato transcription factors and protein kinases among greenhouse-grown plants subjected to well-watered conditions and water deficit during 5 DAT. A significant enhancement of expression was observed for known drought stress-associated genes such as an abscisic acid-responsive elements-binding factor, dehydration-responsive element-binding factor, and homeodomain- zip proteins. Members of calcium-binding proteins showed differential expression under drought stress. For the first time it is reported that knotted1-like homeobox and BEL1-like genes showed altered expression in response to drought stress under a greenhouse condition. In summary, the results suggest that water deprivation during the SR formation period influences root development and expression patterns of stress-responsive genes and those previously found associated with SR formation in sweetpotato

Solonamide B Inhibits Quorum Sensing and Reduces Staphylococcus aureus Mediated Killing of Human Neutrophils

Methicillin-resistant Staphylococcus aureus (MRSA) continues to be a serious human pathogen, and particularly the spread of community associated (CA)-MRSA strains such as USA300 is a concern, as these strains can cause severe infections in otherwise healthy adults. Recently, we reported that a cyclodepsipeptide termed Solonamide B isolated from the marine bacterium, Photobacterium halotolerans strongly reduces expression of RNAIII, the effector molecule of the agr quorum sensing system. Here we show that Solonamide B interferes with the binding of S. aureus autoinducing peptides (AIPs) to sensor histidine kinase, AgrC, of the agr two-component system. The hypervirulence of USA300 has been linked to increased expression of central virulence factors like α-hemolysin and the phenol soluble modulins (PSMs). Importantly, in strain USA300 Solonamide B dramatically reduced the activity of α-hemolysin and the transcription of psma encoding PSMs with an 80% reduction in toxicity of supernatants towards human neutrophils and rabbit erythrocytes. To our knowledge this is the first report of a compound produced naturally by a Gram-negative marine bacterium that interferes with agr and affects both RNAIII and AgrA controlled virulence gene expression in S. aureus

Development of bioluminescent Group B streptococcal strains for longitudinal infection studies

Group B Streptococcus (GBS) remains the leading bacterial cause of invasive neonatal disease, resulting in substantial morbidity and mortality. New therapeutic approaches beyond antibacterial treatment to prevent neonatal disease outcomes are urgent. One significant limitation in studying GBS disease and progression is the lack of non-invasive technologies for longitudinal studies. Here, we develop and compare three bioluminescent GBS strains for in vivo pathogenic analysis. Bioluminescence is based on the luxABCDE operon on a replicative vector (luxGBS-CC17), and the red-shifted firefly luciferase on a replicative vector (fflucGBS-CC17) or integrated in the genome (glucGBS-CC17). We show that luxGBS-CC17 is suitable for in vitro analysis but does not produce a significant bioluminescent signal in infected pups. In contrast, the fflucGBS-CC17 results in a strong bioluminescent signal proportional to the organ colonisation level. However, the stability of the replicative vector depends on the route of infection, especially when pups acquire the bacteria from infected vaginal mucosa. Stable chromosomal integration of luciferase in glucGBS-CC17 leads to significant bioluminescence in both haematological and vertical infection models associated with high systemic colonisation. These strains will allow the preclinical evaluation of treatment efficacy against GBS invasive disease using whole-mouse bioluminescence imaging.info:eu-repo/semantics/publishedVersio

Adventitious root primordia formation and development in stem nodes of ‘Georgia jet’ sweetpotato, Ipomoea batatas

PREMISE OF THE STUDY: Yield in sweetpotato is determined by the number of storage roots produced per plant. Storage roots develop from adventitious roots (ARs) present in stem cuttings that serve as propagation material. Data on the origin of sweetpotato ARs and the effect of nodal position on AR establishment and further development are limited. METHODS: We anatomically described root primordium initiation using stem sections and measured number of root primordia formed at different nodal positions using light microscopy and correlated nodal positions with AR number and length 14 d after planting (DAP). KEY RESULTS: Primordia for ARs initiate at the junction of the stem pith ray and the cambium, on both sides of the leaf gap, and they are well developed before emerging from the stem. The number of ARs that develop from isolated stem nodes 14 DAP corresponded to the number of AR primordia detected inside the stem. The total length of established roots at nodes 9-13 from the apex is about 2-fold longer than at nodes 5-8. CONCLUSIONS: Nodal position (age) has a significant effect on the developmental status and number of root primordia inside the stem, determining the number and length of ARs that have developed by 14 DAP. Adventitious roots originating from nodes 9-13 possess similar AR systems and develop better than those originating from younger nodes 3-8. The mechanism regulating AR initiation in nodes is discussed. This system can serve for studying the effect of environmental conditions on AR initiation, development, and capacity to form storage roots

Transcriptional profiling of maturing tomato (Solanum lycopersicum L.) microspores reveals the involvement of heat shock proteins, ROS scavengers, hormones, and sugars in the heat stress response

Above-optimal temperatures reduce yield in tomato largely because of the high heat stress (HS) sensitivity of the developing pollen grains. The high temperature response, especially at this most HS-sensitive stage of the plant, is poorly understood. To obtain an overview of molecular mechanisms underlying the HS response (HSR) of microspores, a detailed transcriptomic analysis of heat-stressed maturing tomato microspores was carried out using a combination of Affymetrix Tomato Genome Array and cDNA-amplified fragment length polymorphism (AFLP) techniques. The results were corroborated by reverse transcription-PCR (RT-PCR) and immunoblot analyses. The data obtained reveal the involvement of specific members of the small heat shock protein (HSP) gene family, HSP70 and HSP90, in addition to the HS transcription factors A2 (HSFA2) and HSFA3, as well as factors other than the classical HS-responsive genes. The results also indicate HS regulation of reactive oxygen species (ROS) scavengers, sugars, plant hormones, and regulatory genes that were previously implicated in other types of stress. The use of cDNA-AFLP enabled the detection of genes representing pollen-specific functions that are missing from the tomato Affymetrix chip, such as those involved in vesicle-mediated transport and a pollen-specific, calcium-dependent protein kinase (CDPK2). For several genes, including LeHSFA2, LeHSP17.4-CII, as well as homologues of LeHSP90 and AtVAMP725, higher basal expression levels were detected in microspores of cv. Hazera 3042 (a heat-tolerant cultivar) compared with microspores of cv. Hazera 3017 (a heat-sensitive cultivar), marking these genes as candidates for taking part in microspore thermotolerance. This work provides a comprehensive analysis of the molecular events underlying the HSR of maturing microspores of a crop plant, tomato