Glycolipids of turions and leaves of Utricularia vulgaris at different stages of development

Turions of Utricularia vulgaris L. were germinated in long-day conditions at 15°C for 1,3 and 6 days and their glycolipid composition was compared with that of resting but vernalized turions. Digalactosyldiacylglycerides (DGDG), monogalactosyldiacylglycerides (MGDG) and cerebrosides were present at all stages of development. No great changes were found in the glycolipid classes during sprouting but some differences were noted in the proportions of fatty acids. The most common fatty acids in all three glycolipid classes studied were 16:0, 18:0 and 18:2. MGDG and DGDG also contained relatively much 18:3 and its proportion increased during germination. Young turions and full-grown leaves collected from nature contained the same glycolipid classes as the sprouting turions. The developmental stage of the organs studied is reflected in the fatty acid composition of DGDG and MGDG but is not so evident in the cerebrosides. The 18:2 fatty acid is rather typical of the resting turions, especially in DGDG.     

Discovery of rare and highly toxic microcystins from lichen-associated cyanobacterium Nostoc sp. strain IO-102-I

The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. Here we show that a terrestrial cyanobacterium Nostoc sp. strain IO-102-I isolated from a lichen association produces six different microcystins. Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp. strain 152. The dominant microcystin produced by Nostoc sp. strain IO-102-I was the highly toxic [ADMAdda(5)]microcystin-LR, which accounted for ca. 80% of the total microcystins. We assigned a structure of [DMAdda(5)]microcystin-LR and [d-Asp(3),ADMAdda(5)]microcystin-LR and a partial structure of three new [ADMAdda(5)]-XR type of microcystin variants. Interestingly, Nostoc spp. strains IO-102-I and 152 synthesized only the rare ADMAdda and DMAdda subfamilies of microcystin variants. Phylogenetic analyses demonstrated congruence between genes involved directly in microcystin biosynthesis and the 16S rRNA and rpoC1 genes of Nostoc sp. strain IO-102-I. Nostoc sp. strain 152 and the Nostoc sp. strain IO-102-I are distantly related, revealing a sporadic distribution of toxin production in the genus Nostoc. Nostoc sp. strain IO-102-I is closely related to Nostoc punctiforme PCC 73102 and other symbiotic Nostoc strains and most likely belongs to this species. Together, this suggests that other terrestrial and aquatic strains of the genus Nostoc may have retained the genes necessary for microcystin biosynthesis.     

Bacterial metastasis: the host plasminogen system in bacterial invasion

Several pathogenic bacterial species intervene with the mammalian proteolytic plasminogen-plasmin system. Recent developments have been made in understanding the structure and the virulence-associated functions of bacterial plasminogen receptors and activators, in particular by using plasminogen-deficient or transgenic gain-of-function mice. Bacteria can affect the regulation of the plasminogen system by degrading circulating plasmin inhibitors and by influencing the expression levels of mammalian plasminogen activators and activation inhibitors. Interaction with the plasminogen system promotes damage of extracellular matrices as well as bacterial spread and organ invasion during infection, suggesting common mechanisms in migration of eukaryotic and prokaryotic cells.     

The effect of some non-protein amino acids on pollen germination and pollen-tube growth in five species of the Vicieae

Summary The effects of canavanine, ,-diaminobutyric acid, homoarginine and lathyrine on the germination of pollen and on in-vitro growth of pollen tubes were studied in the following species: Lathyrus niger, L. silvestris, Vicia unijuga, Pisum sativum and Cicer arietinum.The effects of these non-protein amino acids depended on their quantity and on the plant species. Every amino acid had a promoting effect on germination and growth at some concentration in some species. Inhibition or promotion of pollen germination and pollen-tube growth were usually parallel. The stronger influence of some amino acid on growth than on germination may be due to slow penetration of the acid into the cell.Homoarginine and lathyrine had a promoting effect at all concentrations in L. niger, a species in which these amino acids occur naturally. In most other species they had, if anything, a very slight inhibitory effect, ,-Diaminobutyric acid and canavanine had the strongest inhibitory effects on the species studied. It seems possible that these amino acids are antimetabolites of common amino acids.It is obvious that non-protein amino acids can form effective hybridization barries, although the conditions in nature are more complex than in vitro. The ability to synthesize a new amino acid may therefore be of evolutionary significance in the isolation of new species and genera.     

Developmental changes in the subcellular structure of the seeds of Atropa belladonna

Subcellular changes in the embryo and endosperm of Atropa belladonna were studied at four developmental stages. The endosperm cells turn to storage cells much earlier than those of the embryo, which matures later. Cells of the cotyledon and radicle are very similar in structure. The young cells contain large osmiophilic spherosomes. The cytoplasm is filled with ribosomes but dictyosomes are very rare. Some proplastids, containing starch, and mitochondria are present in the early developmental stages but do not occur in the dormant cells. During ripening, the vacuoles of the endosperm cells and embryo develop into protein bodies. They become filled with protein material without any recognisable transport mechanism. Protein bodies have several electron-translucent globoid cavities and the protein mass contains a roundish or crystalline body. This body does not stain with potassium iodide but with periodic acid Schiff-reagent and protein stains, indicating that it contains glycoproteins. The embryo and endosperm cells of ripe Atropa seeds are very similar and filled with protein bodies and small spherosomes.     

The uptake of phenylalanine into suspension-cultured cells of Atropa belladonna

When suspension-cultured cells of Atropa belladonna L. were in late growth phase, phenylalanine, one of the early precursors of atropine, was taken up mainly by diffusion without carrier but also actively via mediated transport. The uptake capacity of different callus lines varied from 0.4 to 1.9 μol (g fresh weight)⁻¹ h⁻¹ with an optimum pH at 4.5 or 5.0, depending on the callus line, 2,4-Dinitrophenol (DNP) and KCN inhibited about 35–45% of the total uptake in all tested callus lines, so that a part of the uptke was dependent on metabolic energy.
The rate of phenylalanine uptake was fastest from 2 to 7 days after the start of the suspension culture. The increase was from 50 to 300%, depending on the cell line. The enhancement was mainly due to increased mediated uptake and could be inhibited by cycloheximide during the first days of the suspension culture. Glutamine, added to the nutrient medium, also prevented the increase. The inhibition caused by glutamine together with cycloheximide was not additive. Obviously, glutamine did not directly affect the carrier, but possibly repressed its synthesis. When cells entered the stationary phase, the total uptake began to decrease, and most of it was non-mediated. The suspension cultures of A. belladonna had only limited capacity to regulate the transport of phenylalanine into the cells at this phase of growth.     

Seasonal changes in the chloroplast ultrastructure of Diapensia lapponica

Leaf specimens of evergreen Diapensia lapponica were collected monthly in Northern Finland (ca 70°N) in order to study seasonal changes in the ultrastructure of the chloroplasts of the palisade mesophyll.
The volume fraction of chloroplasts per cell was lowest in summer and increased towards autumn and winter. However, the relative size seemed to be higher in summer than in other seasons. Length/width (L/W) ratio was calculated as an index of the chloroplast shape. The shape varied from elongated (usually concavo-convex in profile), with an L/W ratio from 1.9 to 2.5 in summer, to roundish or irregular (L/W ratio from 1.2 to 1.4) in midwinter. In autumn the chloroplasts were most elongated (LW ratio 2.6). The starch content was highest at the end of June when it constituted 38% of the volume of chloroplast. It decreased from then till November and was absent during the rest of the winter. Changes in the thylakoid system involved an increase in the number of partitions from an average of three in early summer to 11 in autumn and a decrease to M again towards winter. In spring it was up to 7 again. The large grana and high portion of stroma thylakoids observed in late August - September (the period of rhythmic light) are consistent with the high photosynthesis activity reported previously in D. lapponica in laboratory conditions.     

Interaction with Intestinal Epithelial Cells Promotes an Immunosuppressive Phenotype in Lactobacillus casei

Maintenance of the immunological tolerance and homeostasis in the gut is associated with the composition of the intestinal microbiota. We here report that cultivation of Lactobacillus casei ATCC 334 in the presence of human intestinal epithelial cells promotes functional changes in bacteria. In particular, the interaction enhanced the immunosuppressive phenotype of L. casei as demonstrated by the ability of L. casei to generate functional regulatory T cells (CD4+CD25+FoxP3+) and production of the anti-inflammatory cytokine interleukin-10 by human peripheral blood mononuclear cells. The results indicate microbe-host cross-talk that changes features of microbes, and suggest that in vitro simulation of epithelial cell interaction can reveal functional properties of gut microbes more accurately than conventional cultivation.     

Hydrogen Photoproduction by Immobilized N2-Fixing Cyanobacteria: Understanding the Role of the Uptake Hydrogenase in the Long-Term Process

We have investigated two approaches to enhance and extend H₂ photoproduction yields in heterocystous, N₂-fixing cyanobacteria entrapped in thin alginate films. In the first approach, periodic CO₂ supplementation was provided to alginate-entrapped, N-deprived cells. N deprivation led to the inhibition of photosynthetic activity in vegetative cells and the attenuation of H₂ production over time. Our results demonstrated that alginate-entrapped ΔhupL cells were considerably more sensitive to high light intensity, N deficiency, and imbalances in C/N ratios than wild-type cells. In the second approach, Anabaena strain PCC 7120, its ΔhupL mutant, and Calothrix strain 336/3 films were supplemented with N₂ by periodic treatments of air, or air plus CO₂. These treatments restored the photosynthetic activity of the cells and led to a high level of H₂ production in Calothrix 336/3 and ΔhupL cells (except for the treatment air plus CO₂) but not in the Anabaena PCC 7120 strain (for which H₂ yields did not change after air treatments). The highest H₂ yield was obtained by the air treatment of ΔhupL cells. Notably, the supplementation of CO₂ under an air atmosphere led to prominent symptoms of N deficiency in the ΔhupL strain but not in the wild-type strain. We propose that uptake hydrogenase activity in heterocystous cyanobacteria not only supports nitrogenase activity by removing excess O₂ from heterocysts but also indirectly protects the photosynthetic apparatus of vegetative cells from photoinhibition, especially under stressful conditions that cause an imbalance in the C/N ratio in cells.     

Culture-independent evidence for the persistent presence and genetic diversity of microcystin-producing Anabaena (Cyanobacteria) in the Gulf of Finland

The late summer mass occurrences of cyanobacteria in the Baltic Sea are among the largest in the world. These blooms are rarely monotypic and are often composed of a diverse assemblage of cyanobacteria. The toxicity of the blooms is attributed to Nodularia spumigena through the production of the hepatotoxic nodularin. However, the microcystin hepatotoxins have also been reported from the Baltic Sea on a number of occasions. Recent evidence links microcystin production in the Gulf of Finland directly to the genus Anabaena . Here we developed a denaturing gradient gel electrophoresis (DGGE) method based on the mcyE microcystin synthetase gene and ndaF nodularin synthetase gene that allows the culture-independent discrimination of microcystin- and nodularin-producing cyanobacteria directly from environmental samples. We PCR-amplified microcystin and nodularin synthetase genes from environmental samples taken from the Gulf of Finland and separated them on a denaturing gradient gel using optimized conditions. Sequence analyses demonstrate that uncultured microcystin-producing Anabaena strains are genetically more diverse than previously demonstrated from cultured strains. Furthermore, our data show that microcystin-producing Anabaena are widespread in the open Gulf of Finland. Non-parametric statistical analysis suggested that salinity plays an important role in defining the distribution of microcystin-producing Anabaena . Our results indicate that microcystin-producing blooms are a persistent phenomenon in the Gulf of Finland.