A multifunctional serine protease primes the malaria parasite for red blood cell invasion

The malaria parasite Plasmodium falciparum replicates within an intraerythrocytic parasitophorous vacuole (PV). Rupture of the host cell allows release (egress) of daughter merozoites, which invade fresh erythrocytes. We previously showed that a subtilisin-like protease called PfSUB1 regulates egress by being discharged into the PV in the final stages of merozoite development to proteolytically modify the SERA family of papain-like proteins. Here, we report that PfSUB1 has a further role in ‘priming' the merozoite prior to invasion. The major protein complex on the merozoite surface comprises three proteins called merozoite surface protein 1 (MSP1), MSP6 and MSP7. We show that just before egress, all undergo proteolytic maturation by PfSUB1. Inhibition of PfSUB1 activity results in the accumulation of unprocessed MSPs on the merozoite surface, and erythrocyte invasion is significantly reduced. We propose that PfSUB1 is a multifunctional processing protease with an essential role in both egress of the malaria merozoite and remodelling of its surface in preparation for erythrocyte invasion.     

A comprehensive proteome map of bovine cerebrospinal fluid

Cerebrospinal fluid (CSF) is considered as the most promising body fluid target for the discovery of biomarkers for early diagnosis of neurodegenerative diseases such as Creutzfeldt–Jakob disease in humans and bovine spongiform encephalopathy in cattle. For the recognition of disease‐associated changes in bovine CSF protein patterns, a detailed knowledge of this proteome is a prerequisite. The absence of a high‐resolution CSF proteome map prompted us to determine all bovine CSF protein spots that can be visualised on 2‐D protein gels. Using state‐of‐the‐art 2‐DE technology for proteome mapping of bovine ante mortem CSF combined with sensitive fluorescent protein staining and MALDI‐TOF/TOF MS for protein identification, a highly detailed 2‐DE map of the bovine CSF proteome was established. Besides the proteins mapped by earlier studies, this map contains 66 different proteins, including 58 which were not annotated in bovine 2‐DE CSF maps before.     

The role of c-di-GMP signaling in an Aeromonas veronii biovar sobria strain

Aeromonas is a ubiquitous gram-negative bacterium that persists in the environment. It is shown that all isolates of persistent Aeromonas clones show strong biofilm formation ability. C-di-GMP regulates biofilm formation in many bacteria. To investigate the impact of c-di-GMP signaling, we introduced heterologous GGDEF and EAL domain proteins from Salmonella Typhimurium to an Aeromonas veronii biovar sobria strain. Overexpression of the GGDEF domain protein AdrA increased c-di-GMP concentration and biofilm formation and reduced motility. Production of the quorum-sensing signaling molecule C4-homoserine lactone and adhesion to aquatic plant duckweed and amoeba surfaces were enhanced. On the other hand, overexpression of the EAL domain protein YhjH decreased biofilm formation and increased motility.     

Uptake of Mineral Particles by Biomphalaria glabrata (Say.) (Pulmonata,Mollusca) and its Importance for Growth Rate and Egg Production

The ingestion of mineral particles by Biomphalaria glabrata is proved and the importance of these particles in the diet of the snails is investigated. The number of particles ingested rises with the size of the snails and they are retained in quantity in the alimentary tract when an adequate supply is not provided. The size of grit found in the gut differs widely from the mixture offered. Mineral particles are ingested actively and selectively. Quantitative investigations comparing snails cultured with and without sand showed a slight advantage concerning growth and reproduction for snails cultured with sand.     

Intracellular protein binding patterns of the anticancer ruthenium drugs KP1019 and KP1339

The ruthenium compound KP1019 has demonstrated promising anticancer activity in a pilot clinical trial. This study aims to evaluate the intracellular uptake/binding patterns of KP1019 and its sodium salt KP1339, which is currently in a phase I–IIa study. Although KP1339 tended to be moderately less cytotoxic than KP1019, IC₅₀ values in several cancer cell models revealed significant correlation of the cytotoxicity profiles, suggesting similar targets for the two drugs. Accordingly, both drugs activated apoptosis, indicated by caspase activation via comparable pathways. Drug uptake determined by inductively coupled plasma mass spectrometry (ICP-MS) was completed after 1 h, corresponding to full cytotoxicity as early as after 3 h of drug exposure. Surprisingly, the total cellular drug uptake did not correlate with cytotoxicity. However, distinct differences in intracellular distribution patterns suggested that the major targets for the two ruthenium drugs are cytosolic rather than nuclear. Consequently, drug–protein binding in cytosolic fractions of drug-treated cells was analyzed by native size-exclusion chromatography (SEC) coupled online with ICP-MS. Ruthenium–protein binding of KP1019- and KP1339-treated cells distinctly differed from the platinum binding pattern observed after cisplatin treatment. An adapted SEC-SEC-ICP-MS system identified large protein complexes/aggregates above 700 kDa as initial major binding partners in the cytosol, followed by ruthenium redistribution to the soluble protein weight fraction below 40 kDa. Taken together, our data indicate that KP1019 and KP1339 rapidly enter tumor cells, followed by binding to larger protein complexes/organelles. The different protein binding patterns as compared with those for cisplatin suggest specific protein targets and consequently a unique mode of action for the ruthenium drugs investigated.     

Simultaneous intra/extravascular administration of antiproliferative agents as a new strategy to inhibit restenosis: The peak of reactive cell proliferation as a hallmark for the duration of the treatment

Background  

Strictly intravascular approaches for the treatment of postangioplasty restenosis are effective in the intima and the inner parts of the media but may be insufficient to control redundant pathways in the more outer parts of the media and the adventitia. An inverse situation may occur subsequently to a strictly extravascular approach, like the recently suggested pericardial approach in pigs. We hypothesized that simultaneous intra/extravascular administration of anti-restenotic agents inhibits restenosis by blocking all stimulatory pathways in the entire arterial wall.     

Deep sequencing reveals diversity and community structure of complex microbiota in five Mediterranean sponges

Marine sponges harbor dense microbial communities of exceptionally high diversity. Despite the complexity of sponge microbiota, microbial communities in different sponges seem to be remarkably similar. In this study, we used a subset of a previously established 454 amplicon pyrosequencing dataset (Schmitt and Taylor, unpublished data). Five Mediterranean sponges were chosen including the model sponge Aplysina aerophoba to determine the extent of uniformity by defining (i) the core microbial community, consisting of bacteria found in all sponges, (ii) the variable microbial community, consisting of bacteria found in 2–4 sponges, and (iii) the species-specific community, consisting of bacteria found in only one sponge. Using the enormous sequencing depth of pyrosequencing the diversity in each of the five sponges was extended to up to 15 different bacterial phyla per sponge with Proteobacteria and Chloroflexi being most diverse in each of the five sponges. Similarity comparison of bacteria on phylum and phylotype level revealed most similar communities in A. aerophoba and A. cavernicola and the most dissimilar community in Pseudocorticium jarrei. A surprising minimal core bacterial community was found when distribution of 97% operational taxonomic units (OTUs) was analyzed. Core, variable, and species-specific communities were comprised of 2, 26, and 72% of all OTUs, respectively. This indicates that each sponge contains a large set of unique bacteria and shares only few bacteria with other sponges. However, host species-specific bacteria are probably still closely related to each other explaining the observed similarity among bacterial communities in sponges.     

Development of a high-performance liquid chromatographic method for the determination of 11-keto-β-boswellic acid in human plasma

A validated HPLC method for the determination of 11-keto-β-boswellic acid (KBA) in human plasma was developed. The method involves the solid-phase extraction of KBA from plasma followed by a separation with reversed-phase HPLC. Calibration was based on external standardisation and ranged between 0.1 and 2.0 μg KBA per ml plasma. Linearity was established over the entire calibration range and in each case the coefficient of correlation (r²) was above 0.99. The recovery of KBA from plasma was 85.7%. It was further demonstrated that the method can be applied successfully to monitor the level of KBA in plasma.     

Species-Specific Growth Responses to Climate Variations in Understory Trees of a Central African Rain Forest

Basic knowledge of the relationships between tree growth and environmental variables is crucial for understanding forest dynamics and predicting vegetation responses to climate variations. Trees growing in tropical areas with a clear seasonality in rainfall often form annual growth rings. In the understory, however, tree growth is supposed to be mainly affected by interference for access to light and other resources. In the semi-deciduous Mayombe forest of the Democratic Republic of Congo, the evergreen species Aidia ochroleuca, Corynanthe paniculata and Xylopia wilwerthii dominate the understory. We studied their wood to determine whether they form annual growth rings in response to changing climate conditions. Distinct growth rings were proved to be annual and triggered by a common external factor for the three species. Species-specific site chronologies were thus constructed from the cross-dated individual growth-ring series. Correlation analysis with climatic variables revealed that annual radial stem growth is positively related to precipitation during the rainy season but at different months. The growth was found to associate with precipitation during the early rainy season for Aidia but at the end of the rainy season for Corynanthe and Xylopia. Our results suggest that a dendrochronological approach allows the understanding of climate–growth relationships in tropical forests, not only for canopy trees but also for evergreen understory species and thus arguably for the whole tree community. Global climate change influences climatic seasonality in tropical forest areas, which is likely to result in differential responses across species with a possible effect on forest composition over time.