Ubiquitin‐specific protease‐like 1 (USPL1) is a SUMO isopeptidase with essential,non‐catalytic functions

Isopeptidases are essential regulators of protein ubiquitination and sumoylation. However, only two families of SUMO isopeptidases are at present known. Here, we report an activity‐based search with the suicide inhibitor haemagglutinin (HA)‐SUMO‐vinylmethylester that led to the identification of a surprising new SUMO protease, ubiquitin‐specific protease‐like 1 (USPL1). Indeed, USPL1 neither binds nor cleaves ubiquitin, but is a potent SUMO isopeptidase both in vitro and in cells. C13orf22l—an essential but distant zebrafish homologue of USPL1—also acts on SUMO, indicating functional conservation. We have identified invariant USPL1 residues required for SUMO binding and cleavage. USPL1 is a low‐abundance protein that colocalizes with coilin in Cajal bodies. Its depletion does not affect global sumoylation, but causes striking coilin mislocalization and impairs cell proliferation, functions that are not dependent on USPL1 catalytic activity. Thus, USPL1 represents a third type of SUMO protease, with essential functions in Cajal body biology.     

Enzyme Thermistor Analysis of Penicillin in Standard Solutions and in Fermentation Broth

Immobilized penicillinase was applied in an enzyme thermistor for calorimetric analysis of samples containing penicillin G. Standard solutions as well as extracts from fermentation broth were analyzed. The enzyme was applied bound either to porous glass or, when dealing with crude preparations, to the inner surface of nylon tubing. In the fermentation system studied, high concentrations of penicillin were present, thus allowing dilution to reduce the influence of the composition of the medium on the analysis. The useful linear concentration range was from 0.1 to 100 mM. The coefficient of correlation between analytical results obtained with the present method and those from conventional assays was 0.997.     

Dependence of the flash-induced oxygen evolution pattern on the chemically and far red light-modulated redox condition in cyanobacterial photosynthetic electron transport

Flash-induced photosynthetic oxygen evolution was measured in cells and thylakoid preparations from the coccoid cyanobacteria Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 and from the filamentous cyanobacterium Oscillatoria chalybea. The resulting characteristic flash patterns from these cyanobacteria can be chemically altered by addition of exogenously added substances like CCCP, DCPiP and inorganic salts. Potassium chloride, manganese sulfate and calcium chloride affected the sequences by specific increases in the flash yield and/or effects on the transition parameters. Chloride appeared to exert the strongest stimulatory effect on the oxygen yield. In comparison to chloride, both manganese and calcium did not significantly stimulate the flash amplitudes as such, but improved the functioning of the oxygen evolving complex by decreasing the miss parameter alpha. Particular effects were observed with respect to the time constants of the relaxation kinetics of the first two flash signals Y1/Y2 of the cyanobacterial patterns. In the presence of the investigated chemicals the amplitudes of the first two flash signals (Y2 in particular) were increased and the relaxation kinetics were enhanced so that the time constant became about identical to the conditions of steady state oxygen flash amplitudes. The results provide further evidence against a possible participation of either PS I or respiratory processes to Y1/Y2 of cyanobacterial flash patterns. Dramatic effects were observed when protoplasts from Oscillatoria chalybea or cells from Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 were exposed to weak far red background illumination. Under these conditions, Y2 (and to a smaller extent Y1) of otherwise unchanged flash sequences were specifically modified. Y2 was substantially increased and again the relaxation kinetics were accelerated making the signal indistinguishable from a Y(SS) signal. From the mathematical fit of the sequences we conclude that S2 contributes to 10-20% of the S-state distribution (in comparison to 0% in the control). Thus, far red background illumination might represent a valuable means for photosynthetic investigations where high amounts of S2 are required like e. g. EPR measurements. In such experiments the corresponding EPR signals appeared substantially enhanced following far red preillumination (Ahrling and Bader, unpublished observations). Our results clearly show that the 'controversial results' from parts of the literature suggesting the participation of different mechanisms (net oxygen evolution, inhibited uptake processes etc.) are not required to explain the flash-induced oxygen evolution in cyanobacteria: the seemingly 'incompatible' conditions and conformations can be perfectly interconverted by different modulation techniques (chemicals, far red) of the respective redox condition within the water oxidation complex of photosynthesis.     

Pathological and immunological evaluation of different regimens of praziquantel treatment in a mouse model of Schistosoma mansoni infection

BackgroundOne of the considerable challenges of schistosomiasis chemotherapy is the inefficacy of praziquantel (PZQ) at the initial phase of the infection. Immature schistosomes are not susceptible to PZQ at the curative dose. Here, we investigated the efficacy of different PZQ regimens administered during the initial stage of Schistosoma mansoni infection in mice.Methodology/Principal findingsTwo months-old mice were individually infected with 80 S. mansoni cercariae and divided into one infected-untreated control group (IC) and four PZQ-treated groups: PZQ at 100 mg/kg/day for five consecutive days (group PZQ1), PZQ at 100 mg/kg/day for 28 days (group PZQ2), PZQ at 18 mg/kg/day for 28 days (group PZQ3) and a single dose of PZQ at 500 mg/kg (group PZQ4). The treatment started on day one post-infection (p.i), and each group of mice was divided into two subgroups euthanized on day 36 or 56 p.i, respectively. We determined the mortality rate, the parasitological burden, the hepatic and intestinal granulomas, the serum levels of Th-1, Th-2, and Th-17 cytokines, and gene expression. The treatment led to a significant (p < 0.001) reduction of worm burden and egg counts in the intestine and liver in groups PZQ2 and PZQ3. On 56^th day p.i, there was a significant reduction (p < 0.001) of the number and volume of the hepatic granulomas in groups PZQ2 and PZQ3 compared to group PZQ1 or PZQ4. Moreover, in group PZQ3, the serum levels of IFN-γ, TNF-α, IL-13, and IL-17 and their liver mRNA expressions were significantly reduced while IL-10 and TGF-β gene expression significantly increased. The highest mortality rate (81.25%) was recorded in group PZQ2.Conclusion/SignificanceThis study revealed that the administration of PZQ at 18 mg/kg/day for 28 consecutive days was the optimal effective posology for treating S. mansoni infection at the initial stage in a murine model.     

Rainfall manipulation experiments as simulated by terrestrial biosphere models: Where do we stand?

Changes in rainfall amounts and patterns have been observed and are expected to continue in the near future with potentially significant ecological and societal consequences. Modelling vegetation responses to changes in rainfall is thus crucial to project water and carbon cycles in the future. In this study, we present the results of a new model‐data intercomparison project, where we tested the ability of 10 terrestrial biosphere models to reproduce the observed sensitivity of ecosystem productivity to rainfall changes at 10 sites across the globe, in nine of which, rainfall exclusion and/or irrigation experiments had been performed. The key results are as follows: (a) Inter‐model variation is generally large and model agreement varies with timescales. In severely water‐limited sites, models only agree on the interannual variability of evapotranspiration and to a smaller extent on gross primary productivity. In more mesic sites, model agreement for both water and carbon fluxes is typically higher on fine (daily–monthly) timescales and reduces on longer (seasonal–annual) scales. (b) Models on average overestimate the relationship between ecosystem productivity and mean rainfall amounts across sites (in space) and have a low capacity in reproducing the temporal (interannual) sensitivity of vegetation productivity to annual rainfall at a given site, even though observation uncertainty is comparable to inter‐model variability. (c) Most models reproduced the sign of the observed patterns in productivity changes in rainfall manipulation experiments but had a low capacity in reproducing the observed magnitude of productivity changes. Models better reproduced the observed productivity responses due to rainfall exclusion than addition. (d) All models attribute ecosystem productivity changes to the intensity of vegetation stress and peak leaf area, whereas the impact of the change in growing season length is negligible. The relative contribution of the peak leaf area and vegetation stress intensity was highly variable among models.     

Synthesis, structural and electrochemical features of alicyclic and aromatic α,α′-N2- and-S2-dioximate macrobicyclic cobalt(II,III) and ruthenium(II) tris-complexes

The triribbed-functionalized cobalt(II,III) and ruthenium(II) clathrochelate derivatives of the vic-dioximes with two nitrogen or sulfur atoms in α-positions to π-conjugated diazomethine chelate fragments of a macrobicyclic framework were obtained in moderate yields under mild and high dilution conditions by nucleophilic substitution of six reactive chlorine atoms of the boron-capped macrobicyclic cobalt and ruthenium(II) precursors with N₂- and S₂-dinucleophiles (ethylenediamine and the corresponding α-dithiols in the presence of triethylamine, respectively). The complexes obtained were characterized using elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, ¹H and ¹³C{¹H} NMR and EPR spectroscopies, magnetochemistry and X-ray crystallography. The MN₆-coordination polyhedra of all the X-ray studied clathrochelates possess a slightly distorted trigonal prismatic geometry. The encapsulated cobalt(II) ions are shifted from the centers of the cavities formed by the macrobicyclic ligand due to the Jahn-Teller distortion, while the ruthenium and iron(II) ions in their clathrochelate analogs do occupy these centers. The main geometrical parameters of the macrobicyclic frameworks vary with Shannon radius of an encapsulated metal ion. In the case of the tris-ethylenediamine cobalt(III) clathrochelate, the field strength of the macrobicyclic amine ligand is essentially lower than those for their aromatic and aliphatic analogs because of the negative σ_para-effect of the ribbed alkylamine substituents. The magnetometry and EPR data confirmed the low-spin character of the cobalt(II) complexes synthesized. The electrochemically generated oxidized cobalt clathrochelates are stable in the CVA time scale, whereas their ruthenium- and iron-containing analogs as well as the reduced forms of all the cobalt, ruthenium and iron complexes obtained are unstable.     

Ring-based versus disc-based separation of spatial scales: a case study on the impact of arable land proportions on invertebrates in freshwater streams

The impact of different land-use types on species is traditionally estimated by correlating landscape proportions recorded in buffer areas around focal points with species data observed at these sites. If a high proportion of a specific land-use type exists within a small radius, it will be accumulated in larger buffers and may confound the interpretation at larger scales. We sampled freshwater invertebrates in ten streams using cages with artificial substrate and compared the effects of arable land proportions calculated in disc-shaped buffers of increasing radius versus areas calculated from non-overlapping rings of increasing radius. We hypothesize that (1) the accumulative disc-based approach leads to confounding effects across increasing buffer size and that (2) the use of ring-based methods facilitates the identification of relevant scales for conservation measures. The abundance of crustaceans showed a positive relationship with arable land proportions, but Plecoptera abundance and the taxonomic richness of Ephemeroptera and Plecoptera decreased with increasing arable land proportions in the surrounding landscape. Our results further support the presence of confounding effects in disc-based analyses, as correlations between arable land proportions and Crustacea, or Plecoptera, respectively, were affected by the accumulation of small-scale area proportions. The distance at which arable land proportions significantly affected benthic fauna in freshwater streams was consistently shorter if calculated from rings rather than from discs. Although an a priori definition of ring width introduces new challenges, a combined use of disc- and ring-based techniques for the estimation of land-use effects may substantially improve the realization of conservation and protection measures in terrestrial and aquatic systems.