Species concept and morphological differentiation of strains traditionally assigned to Micrasterias truncata

The morphological and molecular differentiation of the Micrasterias truncata (Corda) ex Bréb species complex was investigated. In total, 17 strains traditionally assigned to M. truncata were isolated from different European localities (Czech Republic, southwest France, Ireland), and obtained from public culture collections. In addition, strains of the morphologically similar species, M. decemdentata (Nägeli) W. Archer and M. zeylanica F. E. Fritsch, were also included. Molecular phylogenetic analysis based on trnG^ucc intron sequences revealed five well supported clades. Two Australian strains assigned to M. truncata var. pusilla G. S. West formed a lineage sister to M. zeylanica. This was evident from a concatenated phylogeny based on small subunit rDNA and trnG^ucc intron sequences. The isolated position of these strains was also illustrated by parallel landmark‐based geometric morphometric analysis of cell shapes. The strains NIES 783 and NIES 784 probably represent a separate species. Particular analysis, including additional strains, is needed to resolve the relationship inside this lineage. The second phylogenetic lineage, containing two strains of M. truncata var. semiradiata (Kützing) Wolle, was also different from other strains on the basis of morphometric data. We suggest recognizing this variety as a separate species, Micrasterias semiradiata L.A. Brébisson ex F. T. Kützing. The remaining three clades formed a firmly supported group of the ‘core’M. truncata recognized by both molecular markers. However, neither any morphological, morphometric, nor geographical pattern was detected among members of these three clades. This pattern could be caused by a relatively recent origin of these lineages that may represent a sympatric, truly cryptic species. Strains attributable to traditional morphologically defined variety M. truncata var. neodamensis were nested within the ‘core’M. truncata.     

Calreticulin mRNA and protein are localized to protein bodies in storage maize callus cells

Maize callus cells possess numerous protein bodies which develop as sub-compartments of the endoplasmic reticulum. We localized maize calreticulin mRNAs and protein in maize callus cells using in situ hybridization and immunocytochemistry. Calreticulin mRNAs were selectively targeted to the endoplasmic reticulum (ER) subdomains surrounding protein bodies. Profilin mRNAs, used as a positive control for in situ hybridization experiments, showed distinct and rather diffuse localization pattern. Using both, immunofluorescence and immunogold electron microscopy localization techniques, calreticulin was found to be enriched around and within protein bodies in maize callus storage cells. As a positive control for reticuloplasmins, HDEL antibody revealed labelling of protein bodies and of the nuclear envelope. The identity of protein bodies was confirmed by specific binding of an α zein antibody. These data suggest that calreticulin mRNA is targeted towards protein body forming subdomains of the ER, and that calreticulin is localized and enriched in these protein bodies. The possibility that calreticulin plays an important role in zein retention within the ER and/or its assembly and packaging into protein bodies during protein body biogenesis in maize callus is discussed.     

Small‐scale variation of corticolous microalgal covers: Effects of microhabitat,season, and space

The present study focuses on temporal and microscale spatial variation of the community structure and richness of subaerial microalgae growing on the bark of European beech (Fagus sylvatica) trees in temperate deciduous forests. Subaerial phototrophic biofilms present common and conspicuous microalgal communities growing on a variety of natural and man‐made substrata. However, in comparison with other major microalgal communities such as phytoplankton and microphytobenthos, basic patterns of their spatio‐temporal variation remain largely unknown. The bark samples were collected six times each spring and autumn in a period of 3 years (2010–2013) and were cultured on agar plates, and then individual clonal strains were identified by light microscopy. A total of 55 morphotypes (considered as operational taxonomic units for subsequent analyses) were recognized, which mainly belong to the classes Trebouxiophyceae and Chlorophyceae. Interestingly, temporal variation explained the largest proportion of variation in the community structure. This variation was primarily related to seasonal fluctuations, and although the communities recorded in spring and autumn showed many overlapping taxa, a clear distinction in species composition and abundance was observed. However, the microhabitat characteristics such as bark roughness also significantly structured the microalgal community. Conversely, spatial factors such as the height of the samples above ground or distance of the samples on a trunk seemed to be of lesser importance on this scale. Thus, we concluded that the previously unrecognized seasonal changes, resulting from variation in temperature, humidity, and irradiance, as well as the non‐seasonal temporal changes, possibly resulting from local colonization or extinction of individual taxa, should be considered as one of the important factors in structuring aerial microalgal communities.     

Photosynthesis and chlorophyll content in different areas of fodder cabbage leaves

Byla stanovena intensita fotosynthesy a obsah chlorofylu v terěících z r?znych okrsk? ?epele listu krmné kapusty odr. Coulet de Flandre. Obsah chlorofylu na jednotku plochy byl vy??í v apikální ?ásti list? ne? v ?ásti basální, vy??í ve st?edové ne? v okrajové ?ásti listu. Nebyly nalezeny podstatné rozdily v intensitě fotosynthesy ve vzorcích z r?znych ?ástí listu. Intensita fotosynthesy není p?ímo úměrná váze su?iny daného vzorku, a?koliv vàha su?iny na jednotku plochy je podstatně vy??í v apikálni ne? v basální ?ásti listové plochy.     

Über die Chromosomenzahlen einiger Heilpflanzen

Zusammenfassung Die Verfasser haben an Mikrotomschnitten die diploiden Chromosomenzahlen einiger Heilpflanzen festgestellt. Sie betragen beiRauwolfia serpentina 2 n=22, beiCassia acutifolia 2 n=28, beiCnicus benedictus 2 n=22, beiThymus vulgaris 2 n=30, beiFagopyrum esculentum undFagopyrum tataricum 2 n=16. Ferner wurden beiRauwolfia serpentina zwei Satelliten und bei den beiden Buchweizenarten je ein Satellit gefunden. Die beiCnicus, Thymus undFagopyrum beobachteten Chromosomenzahlen entsprechen denen, die andere Autoren an Material von anderen Standorten festgestellt haben. Die Satelliten wurden von diesen Autoren nicht gefunden.Die Basiszahl beiCnicus ist b=11, was diese Gattung der GattungCarduus genetisch annähert, deren ArtenC. defloratus undC. acanthoides ebenfalls 2 n=22 Chromosomen besitzen, eine Zahl, die in der GattungCirsium nicht vorkommt, mit welcher aberCarduus nicht selten in genetischen Zusammenhang gebracht wird.