Role of phosphatidylglycerol in the function and assembly of Photosystem II reaction center, studied in a cdsA-inactivated PAL mutant strain of Synechocystis sp. PCC6803 that lacks phycobilisomes

To analyze the role of phosphatidylglycerol (PG) in photosynthetic membranes of cyanobacteria we used two mutants of Synechocystis sp. PCC6803: the PAL mutant which has no phycobilisomes and shows a high PSII/PSI ratio, and a mutant derived from it by inactivating its cdsA gene encoding cytidine 5'-diphosphate diacylglycerol synthase, a key enzyme in PG synthesis. In a medium supplemented with PG the PAL/ΔcdsA mutant cells grew photoautotrophically. Depletion of PG in the medium resulted (a) in an arrest of cell growth and division, (b) in a slowdown of electron transfer from the acceptor Q_A to Q_B in PSII and (c) in a modification of chlorophyll fluorescence curve. The depletion of PG affected neither the redox levels of Q_A nor the S₂ state of the oxygen-evolving manganese complex, as indicated by thermoluminescence studies. Two-dimensional PAGE showed that in the absence of PG (a) the PSII dimer was decomposed into monomers, and (b) the CP43 protein was detached from a major part of the PSII core complex. [³⁵S]-methionine labeling confirmed that PG depletion did not block de novo synthesis of the PSII proteins. We conclude that PG is required for the binding of CP43 within the PSII core complex.     

Intracellular targeting of calmodulin mRNAs in primary hippocampal cells.

We investigated the intracellular distribution of the mRNAs corresponding to the three non-allelic CaM genes in cultured hippocampal cells by in situ hybridization with digoxigenin-labeled gene-specific riboprobes. In neurons the perikaryon was heavily stained and strong dendritic mRNA targeting was detected for all three CaM genes. The color labeling exhibited a punctate distribution, suggesting that CaM mRNAs are transported in RNA granules. Immunocytochemistry for S100 demonstrated that glial cells express CaM mRNAs at a very low level. A minority of the cultured cells were negative for either labeling.     

Central Venous-To-Arterial CO2-Gap May Increase in Severe Isovolemic Anemia

Despite blood transfusions are administered to restore adequate tissue oxygenation, transfusion guidelines consider only hemoglobin as trigger value, which gives little information about the balance between oxygen delivery and consumption. Central venous oxygen saturation is an alternative, however its changes reflect systemic metabolism and fail to detect regional hypoxia. A complementary parameter to ScvO₂ may be central venous-to-arterial carbon dioxide difference (CO₂-gap). Our aim was to investigate the change of alternative transfusion trigger values in experimental isovolemic anemia. After splenectomy, anesthetized Vietnamese mini pigs (n = 13, weight range: 18–30 kg) underwent controlled bleeding in five stages (T₁–T₅). During each stage approximately 10% of the estimated starting total blood volume was removed and immediately replaced with an equal volume of colloid. Hemodynamic measurements and blood gas analysis were then performed. Each stage of bleeding resulted in a significant fall in hemoglobin, the O₂-extraction increased significantly from T₃ and ScvO₂ showed a similar pattern and dropped below the physiological threshold of 70% at T₄. By T₄ CO₂-gap increased significantly and well correlated with VO₂/DO₂ and ScvO₂. To our knowledge, this is the first study to show that anemia caused altered oxygen extraction may have an effect on CO₂-gap.     

Hemin and bile pigments are the secondary structure regulators of intrinsically disordered antimicrobial peptides

The interaction of protoporphyrin compounds of human origin with the major bee venom component melittin (26 a.a., Z +6) and its hybrid derivative (CM15, 15 a.a., Z +6) were studied by a combination of various spectroscopic methods. Throughout a two‐state, concentration‐dependent process, hemin and its metabolites (biliverdin, bilirubin, bilirubin ditaurate) increase the parallel β‐sheet content of the natively unfolded melittin, suggesting the oligomerization of the peptide chains. In contrast, α‐helix promoting effect was observed with the also disordered but more cationic CM15. According to fluorescence quenching experiments, the sole Trp residue of melittin is the key player during the binding, in the vicinity of which the first pigment molecule is accommodated presumably making indole‐porphyrin π‐π stacking interaction. As circular dichroism titration data suggest, cooperative association of additional ligands subsequently occurs, resulting in multimeric complexes with an apparent dissociation constant ranged from 20 to 65 μM. Spectroscopic measurements conducted with the bilirubin catabolite urobilin and stercobilin refer to the requirement of intact dipyrrinone moieties for inducing secondary structure transformations. The binding topography of porphyrin rings on a model parallel β‐sheet motif was evaluated by absorption spectroscopy and computational modeling showing a slipped‐cofacial binding mode responsible for the red shift and hypochromism of the Soret band. Our results may aid to recognize porphyrin‐responsive binding motifs of biologically relevant, intrinsically disordered peptides and proteins, where transient conformations play a vital role in their functions.     

The first record of subtropical insects (Thysanoptera) in central Europe: long‐distance transport of airborne thrips,applying three‐dimensional backward trajectories

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A comparative autoradiography study in post mortem whole hemisphere human brain slices taken from Alzheimer patients and age-matched controls using two radiolabelled DAA1106 analogues with high affinity to the peripheral benzodiazepine receptor (PBR) system

The binding of two radiolabelled analogues (N-(5-[125I]Iodo-2-phenoxyphenyl)-N-(2,5-dimethoxybenzyl)acetamide ([125I]desfluoro-DAA1106) and N-(5-[125I]Fluoro-2-phenoxyphenyl)-N-(2-[125I]Iodo-5-methoxybenzyl)acetamide ([125I]desmethoxy-DAA1106) of the peripheral benzodiazepine receptor (PBR) (or TSPO, 18kDa translocator protein) ligand DAA1106 was examined by in vitro autoradiography on human post mortem whole hemisphere brain slices obtained from Alzheimer's disease (AD) patients and age-matched controls. Both [(125)I]desfluoro-IDAA1106 and [(125)I]desmethoxy-IDAA1106 were effectively binding to various brain structures. The binding could be blocked by the unlabelled ligand as well as by other PBR specific ligands. With both radiolabelled compounds, the binding showed regional inhomogeneity and the specific binding values proved to be the highest in the hippocampus, temporal and parietal cortex, the basal ganglia and thalamus in the AD brains. Compared with age-matched control brains, specific binding in several brain structures (temporal and parietal lobes, thalamus and white matter) in Alzheimer brains was significantly higher, indicating that the radioligands can effectively label-activated microglia and the up-regulated PBR/TSPO system in AD. Complementary immunohistochemical studies demonstrated reactive microglia activation in the AD brain tissue and indicated that increased ligand binding coincides with increased regional microglia activation due to neuroinflammation. These investigations yield further support to the PBR/TSPO binding capacity of DAA1106 in human brain tissue, demonstrate the effective usefulness of its radio-iodinated analogues as imaging biomarkers in post mortem human studies, and indicate that its radiolabelled analogues, labelled with short half-time bioisotopes, can serve as prospective in vivo imaging biomarkers of activated microglia and the up-regulated PBR/TSPO system in the human brain.     

Peptide conjugates of therapeutically used antitubercular isoniazid—design,synthesis and antimycobacterial effect

Tuberculosis (TB) is a bacterial infectious disease caused by Mycobacterium tuberculosis, a slow‐growing, powerful human pathogen which can survive in the host macrophages. In the chemotherapy of such intracellular pathogens it is necessary to achieve relatively high level of the drug in blood to attain therapeutically effective concentration in infected cells, which presumably has several serious side effects on healthy tissues. The elimination of M. tuberculosis from infected phagocytes could be more efficient with target cell‐directed delivery of antituberculars. A particularly promising approach is to conjugate a drug moiety to a peptide based carrier. The conjugates are chemically constructed to target release by hydrolysis (enzymatic and/or chemical) to liberate the active compound. Here we report the synthesis, characterisation and antimycobacterial evaluation of isoniazid (INH) peptide conjugates. As carrier moiety T‐cell epitope of immundominant 16‐kDa protein of M. tuberculosis and tuftsin‐derived peptides were used. To conjugate INH two synthetic methods were developed, where INH was coupled directly to the peptides or through a heterobifunctional reagent. We found that all of the INH conjugates were effective against M. tuberculosis and the minimal inhibitory concentration (MIC) values were comparable to the free INH moiety. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.     

Species-specific distribution of two sympatric Maculinea butterflies across different meadow edges

An important consequence of habitat fragmentation is the increase of edge habitats. Environmental factors in the edges are different from those in the interiors, which causes changes in the distribution of plant and animal species. We aimed to study how edges affect the distribution of two butterfly species within meadow fragments. We therefore investigated the effect of distance from edge and edge type (road edge versus tree edge) on two sympatric large blue species (Maculinea teleius and M. nausithous). Our results showed that edge type had contrasting effects on the two species. M. teleius favoured both interiors and road edges, while M. nausithous preferred the tree edges. In the case of the latter species a strong positive edge effect was also found. This kind of within-habitat niche segregation is probably related to the different microenvironmental conditions at the edges. Foodplant density did not seem to limit the distribution of these species. Our results suggest that interiors of meadows are important for M. teleius, while tree edges maintain the habitats of the regionally rarer butterfly, M. nausithous.     

Application of spontaneously immortalized odontoblast cells in tooth regeneration

Here, we report on the first attempt to bioengineer tooth using a spontaneously immortalized mesenchymal cell line. To assess the odontogenic potential of this cell line, odontoblast-lineage cells (OLC) were re-associated with competent dental epithelium isolated from E14.5 mice. A novel three-dimensional organ germ culture method was applied to nurture the constructs in vitro. Additionally, recombinants were transplanted under the kidney capsule in host animals for 2 weeks. Transplants developed into tooth tissues in one-third of the cases. OLC-derived GFP-positive cells could be identified in mineralizing tooth germs by immunohistochemistry. OLCs were capable of intercellular and cell-matrix communication, thus they eventually differentiated into functional odontoblasts. In summary, we managed to utilize OLCs for dental mesenchyme substitution in tooth regeneration experiments. Therefore, our spontaneously transformed cell line proved its potential for future complex, tooth developmental and bioengineering studies.