Dynamics of photosynthetic complexes in the thylakoid membranes from higher plants

PhDPhotosynthetic machinery in higher plants is localised in the thylakoids enclosed in a chloroplast. To optimise and regulate the photosynthetic efficiency under different, rapidly changeable environmental conditions the dynamics of the thylakoid membrane components is required. It has been invoked in several contexts, for example during assembly and turnover of the photosynthetic apparatus, regulation of light-harvesting and photosynthetic electron transport. In this study, by employing a confocal FRAP technique combined with freeze-fracture electron microscopy, I addressed a fundamental problem of visualising the mobility and distribution of photosynthetic complexes in a direct way close to the situation in vivo - the thylakoids of intact chloroplasts isolated from green plants. Firstly, I provided direct evidence that the dynamic changes in the distribution of photosynthetic complexes are involved in two high-light related physiological phenomena, namely photoinhibition and non-photochemical quenching. My study indicates that the photoinhibited membranes exhibit an elevated level of protein mobility accompanied by a decreased spacing between the complexes with the opposite effect observed in the photoprotective state. Secondly, my work allowed the identification of some key elements that are responsible for controlling the mobility under different physiological conditions such as: (1) phosphorylation of PSII core complexes after photoinhibition, (2) PsbS protein enhancing the membrane fluidity in a dark-adapted state and decreasing it after light treatment, (3) different xanthophyll composition of light-harvesting antenna with particular attention being paid to zeaxanthin which decreases the size of mobile fraction, (4) the degree of macromolecular crowding and the organisation of PSII-LHCII supercomplexes in the grana membranes which is dependent strongly on individual light-harvesting proteins, the minor antenna 4 complexes in particular. Lastly, a completely new approach of visualising the mobility of photosynthetic machinery in intact leaves has been introduced as a useful tool to study different aspects of plant acclimation and physiology under natural conditions.Biotechnology and Biological Science Research Council. University of London Central Research fun

Fusarium head blight resistance and mycotoxin profiles of four Triticum species genotypes

Fusarium head blight (FHB) resistance was evaluated for accessions of four Triticum species, including bread wheat (modern and old cultivars), spelt, emmer, and einkorn. Fusarium head infection, Fusarium kernel damage and accumulation of trichothecene toxins (deoxynivalenol, nivalenol) in grains were analysed. Modern bread wheat cultivars were the most susceptible to head infection, and emmer and einkorn accessions were the most resistant. Kernel damage was the least for emmer and spelt and greatest for bread wheat. No significant differences between the four host species were observed for toxin accumulation. However, the greatest amounts of deoxynivalenol were detected in the grains of modern wheat cultivars and the least in old bread wheat cultivars. The greatest amount of nivalenol was detected in einkorn grains and the least in old bread wheat cultivars. Wide variability of resistance of all types in all four species was observed. Accessions resistant to FHB and toxin accumulation in grains were identified

Multifocal intracerebral haemorrhage in case of staphylococcal sepsis in patient with myasthenia gravis and risk factors for cerebrovascular disease

W pracy przedstawiono przypadek chorego z miastenią, obciążonego czynnikami ryzyka udaru mózgu, u którego rozwinęła się posocznica gronkowcowa z zapaleniem wsierdzia. W przebiegu choroby wystąpił ciężki, wieloogniskowy udar krwotoczny, co wywołało zgon. Zwrócono uwagę na szczególne zagrożenie powikłaniami infekcyjno-naczyniowymi u osób w starszym wieku, obciążonych czynnikami ryzyka udaru mózgu, leczonych immunosupresyjnie w warunkach szpitalnych.The authors present a case of patient with myasthenia gravis, with coexisting risk factors for cerebrovascular disease, who developed staphylococcal sepsis complicated with endocarditis. In the course of the disease multifocal intracerebral haemorrhage emerged, which caused the patient's death. Special attention was drown to risk of infectious and vascular complications in elderly patients with factors predisposing to cerebrovascular disease and treated with immunosupressive agents during their stay in hospital

Micro-CT 3D imaging reveals the internal structure of three abyssal xenophyophore species (Protista, Foraminifera) from the eastern equatorial Pacific Ocean

Xenophyophores, giant foraminifera, are distinctive members of the deep-sea megafauna that accumulate large masses of waste material (‘stercomare’) within their agglutinated tests, and organise their cells as branching strands enclosed within an organic tube (the ‘granellare’ system). Using non-destructive, three-dimensional micro-CT imaging we explored these structures in three species from the abyssal eastern Pacific Clarion-Clipperton Zone (CCZ). In Psammina spp., the low-density stercomare occupied much of the test interior, while high-density granellare strands branched throughout the structure. In Galatheammina sp. the test comprised a mixture of stercomare and test particles, with the granellare forming a web-like system of filaments. The granellare occupied 2.8–5.1%, the stercomare 72.4–82.4%, and test particles 14.7–22.5%, of the ‘body’ volume in the two Psammina species. The corresponding proportions in Galatheammina sp. were 1.7% (granellare), 39.5% (stercomare) and 58.8% (test particles). These data provide a potential basis for estimating the contribution of xenophyophores to seafloor biomass in areas like the CCZ where they dominate the megafauna. As in most xenophyophore species, the granellare hosted huge numbers of tiny barite crystals. We speculate that these help to support the extensive granellare system, as well as reducing the cell volume and lightening the metabolic burden required to maintain it

Confocal laser scanning microscopy as a valuable tool in Diptera larval morphology studies

Larval morphology of flies is traditionally studied using light microscopy, yet in the case of fine structures compound light microscopy is limited due to problems of resolution, illumination and depth of field, not allowing for precise recognition of sclerites’ edges and interactions. Using larval instars of cyclorrhaphan Diptera, we show the usefulness of confocal laser scanning microscopy (CLSM) for studying the morphological characters of immature stages by taking advantage of the autofluorescent properties of cephaloskeleton structures. We compare data obtained from killed but unprepared larvae with those from larvae prepared by clearing according to two commonly used methods, either with potassium hydroxide or with Hoyer’s medium. We also evaluated the CLSM application for examining already slide-mounted larvae stored in museum collections and those freshly prepared. Our results indicate that CLSM and 3D reconstruction are excellent for visualizing small, compound structures of cylrorrhaphan larvae cephaloskeleton, if appropriate clearing techniques, i.e. the application of KOH, are used. Maximum intensity projection of confocal data sets obtained from material freshly prepared and that stored in museum collection does not differ. Because of this and the fact that KOH is commonly used as a clearing method to examine the cephaloskeleton of Diptera larvae, it is possible, and highly recommended, to use slides already prepared with this method for re-examination by CLSM. We conclude that CLSM application can be an invaluable source of data for studies of larval morphology of Cyclorrhapha by way of taxonomic diagnoses, character identification and improvement in characters homologization.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited

Variation for resistance to Fusarium head blight in winter and spring wheat varieties studied in 2009–2016.

W latach 2009–2016 w doświadczeniach infekcyjnych badano podatność na fuzariozę kłosów ogółem 142 odmian pszenicy ozimej oraz 53 odmian pszenicy jarej. Kłosy zakażano sztucznie izolatami Fusarium culmorum. Ze względu na duże zróżnicowanie średniego nasilenia fuzariozy kłosów w kolejnych latach, wartości indeksów fuzariozy kłosów w poszczególnych latach poddano standaryzacji. Z wartości standaryzowanych wyliczono średnie wieloletnie dla odmian. Wśród odmian pszenicy ozimej najmniejszą podatność na fuzariozę kłosów wykazały wzorce odporne oraz odmiany Fregata, Olivin, Petrus, Turnia, Nateja, Piko i Dorota. Najbardziej podatne na fuzariozę kłosów były odmiany: Muszelka, Rapsodia, Kris, Kampana, Bagou, Belenus, Alcazar, Torrild, Banderola, Forkida. Wśród odmian pszenicy jarej najmniejszą podatność na fuzariozę kłosów wykazały również wzorce odporne oraz odmiany Pasteur, Jasna, Histra, Raweta i Izera. Najbardziej podatne były odmiany pszenicy twardej: SMH 87 i Strongfield oraz pszenicy zwyczajnej Banti, Nawra, Griwa, Radocha, Cytra i Helia.n 2009–2016 in the field experiments resistance to Fusarium head blight of 142 varieties of winter wheat and 53 varieties of spring wheat was evaluated. Wheat heads were inoculated with Fusarium culmorum isolates Due to the large diversity of medium severity of Fusarium head blight in subsequent years, the values of the Fusarium head blight indexes in different years were standardized. With the standardized value, averages for individual varieties were calculated. Among winter wheat varieties, the highest resistance to Fusarium head blight showed resistant check varieties and varieties ‘Fregata’, ‘Olivin’, ‘Petrus’, ‘Turnia’, ‘Nateja’, ‘Piko’ and ‘Dorota’. The most susceptible to Fusarium head blight were varieties: ‘Muszelka’, ‘Rapsodia’, ‘Kris’, ‘Kampana’, ‘Bagou’, ‘Belenus’, ‘Alcazar’, ‘Torrild’, ‘Banderola’ and ‘Forkida’. Among the varieties of spring wheat, the highest resistance to Fusarium head blight also showed resistant check varieties and varieties ‘Pasteur’, ;Jasna’, ‘Histra’, ‘Raweta’, ‘Izera’. The most susceptible were varieties of durum wheat: ‘SMH 87’, and ‘Strongfield’ and bread wheat ‘Banti’, ‘Nawra’, ‘Griwa’, ‘Radocha’, ‘Cytra’ and ‘Helia’

Resistance of spring wheat cultivars and lines to Fusarium head blight caused by Fusarium culmorum

Badano odporność na fuzariozę kłosów 25 odmian pszenicy jarej oraz 35 odmian i linii z kolekcji form odpornych Zakładu Fitopatologii IHAR — PIB. Badania prowadzono w latach 2010–2012 na polach doświadczalnych w Radzikowie. Kłosy pszenicy inokulowano izolatami Fusarium culmorum. Oceniano stopień porażenia kłosa (indeks fuzariozy kłosów). Odmiany wykazały średnią podatność na fuzariozę kłosów. Indeks fuzariozy kłosów wyniósł 28,1%, wystąpiło znaczne, istotne statystycznie, zróżnicowanie tej cechy. Zakres zmienności mieścił się w granicach 15,8–45,6%. Znaleziono zarówno odmiany odporne na porażenie kłosa (Napola, Raweta, Torka, Histra, Pasteur), jak i odmiany o bardzo wysokiej podatności (Banti, Nawra, Griwa). Odmiany i linie z kolekcji były w większości wysoko odporne na fuzariozę kłosów. Indeks fuzariozy kłosów wyniósł 5,5%, zakres zmienności mieścił się w granicach: 0–26,9%. Bardzo wysoką odporność wykazały linie CJ 9306 i CJ 9311 oraz odmiana Sumai 3, u których nie obserwowano objawów choroby.Resistance to Fusarium head blight was studied in 25 spring wheat cultivars from the Polish National List and 35 cultivars/lines from the collection of the resistant forms of the Department of Plant Pathology. Experiments were conducted over years 2010–2012 in the experimental fields in Radzików, Poland. Heads of spring wheat were inoculated with Fusarium culmorum. Severity of the head infection (Fusarium head blight index) was evaluated. Spring wheat cultivars were on average moderately susceptible, however wide, statistically significant, variability of reaction occurred. Fusarium head blight index was 28.1%, at a range 15.8–45.6%. Resistant cultivars were found (Napola, Raweta, Torka, Histra, Pasteur), as well as some highly susceptible cultivars were observed (Banti, Nawra, Griwa). Cultivars and lines from the collection were in majority highly resistant to FHB. Fusarium head blight index was 5.5%, at a range 0–26.0%. Lines ‘CJ 9306’ i ‘CJ 9311’ and cultivar Sumai 3 were very highly resistant and showed no symptoms of disease

Higher Fusarium Toxin Accumulation in Grain of Winter Triticale Lines Inoculated with Fusarium culmorum as Compared with Wheat

Resistance to Fusarium head blight in 32 winter triticale and 34 winter wheat accessions was evaluated. Triticale and wheat were sown in field experiments in two locations. At the time of flowering, heads were inoculated with three Fusarium culmorum isolates. Fusarium head blight index was scored and after the harvest percentage of Fusarium damaged kernels was assessed. Grain was analysed for type B trichothecenes (deoxynivalenol and derivatives, nivalenol) and zearalenone (ZEN) content. The average Fusarium head blight indexes were 28.0% for wheat and 19.2% for triticale accessions. The percentage of Fusarium damaged kernels was also higher for wheat and came to 55.6%, while for triticale this figure was 40.2%. The average content of deoxynivalenol (DON) for wheat amounted to 11.65 mg/kg and was lower than the result for triticale which was 14.12 mg/kg. The average contents of nivalenol were similar in both cereals: 4.13 mg/kg and 5.19 mg/kg for wheat and triticale respectively. Considerable amounts of DON derivatives in the cereals were also detected. The ZEN content in the grain was 0.60 mg/kg for wheat and 0.66 mg/kg for triticale. Relationships between Fusarium head blight index, Fusarium damaged kernels and mycotoxin contents were statistically significant for wheat and mostly insignificant for triticale. Triticale proved to have less infected heads and kernels than wheat. However, the content of type B trichothecenes was higher in triticale grain than in wheat grain

Fusarium head blight resistance of types I and II in wheat and triticale

Określano odporności na infekcję (typ I) oraz na rozprzestrzenianie się Fusarium w kłosie (typ II) u 146 odmian i linii pszenicy ozimej oraz 30 linii pszenżyta ozimego. Kłosy inokulowano poprzez opryskiwanie lub punktową iniekcję zawiesiny zarodników Fusarium culmorum do środkowego kłoska w kłosie. Średnia odporność typu I wyniosła 2,4 punkty infekcji dla pszenicy oraz 2,9 dla pszenżyta. Różnica w odporności typu I pomiędzy pszenicą i pszenżytem była istotna statystycznie. Średnia odporność typu II wyniosła 2,4 porażone kłoski dla pszenicy oraz 2,1 dla pszenżyta. Różnica w odporności typu II pomiędzy pszenicą i pszenżytem była istotna statystycznie. Brak było zależności pomiędzy odpornością obu typów. Odporność pszenicy na fuzariozę kłosów określona w warunkach polowych korelowała istotnie ze odpornością typu I oraz II. W przypadku pszenżyta odporność polowa korelowała istotnie jedynie z odpornością typu II.Resistance to initial infection (type I) and to the spread of Fusarium within the spike (type II) of 146 cultivars and lines of winter wheat and 30 lines of winter triticale was determined. Spikes were inoculated by spraying or injection into the middle spikelet of the spore suspension of Fusarium culmorum. The average resistance of type I amounted to 2.4 points of infection for wheat and 2.9 for triticale. The difference in resistance type I between wheat and triticale was statistically significant. The average resistance of type II amounted to 2.4 infested spikelets for wheat and 2.1 for triticale. The difference in type II resistance between wheat and triticale was statistically significant. There was no relationship between both types of resistance. Wheat resistance to Fusarium blight in field conditions significantly correlated with resistances of the type I and type II. In the case of triticale field resistance correlated significantly only with type II resistance