New Thinking in Punt Morphology

This note is to reflect the thoughts, practical work and hopes of two workers in the Netherlands who are angaged in this branch of science, Dr. B.M.Moeliono of the Botanical laboratory at Groningen, and myself at the Rijskherbarium at laide

THE TAXONOMIC POSITION OF PAPUODENDRON C.T. WHITE AS ELUCIDATED BY ANATOMICAL CHARACTERS

When, in 1946, White described Papuodendron lepidotum from New Guinea, he apparently hesitated to incorporate this species in the Bombacaceae

NEW THINKING IN PUNT MORPHOLOGY

This note is to reflect the thoughts, practical work and hopes of two workers in the Netherlands who are angaged in this branch of science, Dr. B.M.Moeliono of the Botanical laboratory at Groningen, and myself at the Rijskherbarium at laide

Structural Adaptability Facilitates Histidine Heme Ligation in a Cytochrome P450

Almost all known members of the cytochrome P450 (CYP) superfamily conserve a key cysteine residue that coordinates the heme iron. Although mutation of this residue abolishes monooxygenase activity, recent work has shown that mutation to either serine or histidine unlocks non-natural carbene- and nitrene-transfer activities. Here we present the first crystal structure of a histidine-ligated P450. The T213A/C317H variant of the thermostable CYP119 from Sulfolobus acidocaldarius maintains heme iron coordination through the introduced ligand, an interaction that is accompanied by large changes in the overall protein structure. We also find that the axial cysteine C317 may be substituted with any other amino acid without abrogating folding and heme cofactor incorporation. Several of the axial mutants display unusual spectral features, suggesting that they have active sites with unique steric and electronic properties. These novel, highly stable enzyme active sites will be fruitful starting points for investigations of non-natural P450 catalysis and mechanisms

Non-natural Olefin Cyclopropanation Catalyzed by Diverse Cytochrome P450s and Other Hemoproteins

Recent work has shown that engineered variants of cytochrome P450_(BM3) (CYP102A1) efficiently catalyze non-natural reactions, including carbene and nitrene transfer reactions. Given the broad substrate range of natural P450 enzymes, we set out to explore if this diversity could be leveraged to generate a broad panel of new catalysts for olefin cyclopropanation (i.e., carbene transfer). Here, we took a step towards this goal by characterizing the carbene transfer activities of four new wild-type P450s that have different native substrates. All four were active and exhibited a range of product selectivities in the model reaction: cyclopropanation of styrene by using ethyl diazoacetate (EDA). Previous work on P450_(BM3) demonstrated that mutation of the axial coordinating cysteine, universally conserved among P450 enzymes, to a serine residue, increased activity for this non-natural reaction. The equivalent mutation in the selected P450s was found to activate carbene transfer chemistry both in vitro and in vivo. Furthermore, serum albumins complexed with hemin were also found to be efficient in vitro cyclopropanation catalysts

Quality measurement of out-patient neuropsychological therapy after stroke in Germany: definition of indicators and retrospective pilot study

Background: In contrast to the hospital setting, today little work has been directed to the definition, measurement, and improvement of the quality of out-patient medical and therapeutic care. We developed a set of indicators to measure the quality of out-patient neuropsychological therapy after stroke. Methods: The indicators cover core and interdisciplinary aspects of out-patient neuropsychological work such as mediation of patients into social care in case of need. Selection of the quality-indicators was done together with a consensus group of out-patient therapists and supported by evidence, validity, reliability as well as estimated relevance and variability with the quality of care. The set of indicators was further tested in a retrospective cohort study. Anonymous data of 104 patients were collected from out-patient clinical records of five clinics between November 2017 and April 2018. Associations between process and outcome quality were estimated exploitatively. Results: Results allowed for the identification of areas with greater variability in the quality of process care and indicated that attention training as recommended by current guidelines had the lowest overall rate for meeting the quality-aim (met in 44% of the cases). This was followed by time<1month until the start of therapy (63% met) and mediation into social care in case of need (65% met). We further observed that overall quality and involving relatives in the therapy was associated with higher rates of professional reintegration (p-value=0.03). However, the need for mediation into social care was associated with a reduced chance for successful professional reintegration (p-value=0.009). Conclusion: In conclusion, we describe a first set of quality indicators which cover different aspects of out-patient neuropsychological therapy and sufficient variability with care. First data further suggests that meeting the specified quality aims may indeed have relevant effects on outcomes

Structural and functional consequences of removing the N-terminal domain from the magnesium chelatase ChlH subunit of Thermosynechococcus elongatus

Magnesium chelatase (MgCH) initiates chlorophyll biosynthesis by catalysing the ATP-dependent insertion of Mg2+ into protoporphyrin. This large enzyme complex comprises ChlH, I and D subunits, with I and D involved in ATP hydrolysis, and H the protein that handles the substrate and product. The 148 kDa ChlH subunit has a globular N-terminal domain attached by a narrow linker to a hollow cage-like structure. Following deletion of this ~18 kDa domain from the Thermosynechoccus elongatus ChlH, we used single particle reconstruction to show that the apo- and porphyrin-bound forms of the mutant subunit consist of a hollow globular protein with three connected lobes; superposition of the mutant and native ChlH structures shows that, despite the clear absence of the N-terminal ‘head’ region, the rest of the protein appears to be correctly folded. Analyses of dissociation constants shows that the ΔN159ChlH mutant retains the ability to bind protoporphyrin and the Gun4 enhancer protein, although the addition of I and D subunits yields an extremely impaired active enzyme complex. Addition of the Gun4 enhancer protein, which stimulates MgCH activity significantly especially at low Mg2+ concentrations, partially reactivates the ΔN159ChlH–I–D mutant enzyme complex, suggesting that the binding site or sites for Gun4 on H do not wholly depend on the N-terminal domain

Coherent X-ray Diffractive Imaging; applications and limitations

The inversion of a diffraction pattern offers aberration-free diffraction-limited 3D images without the resolution and depth-of-field limitations of lens-based tomographic systems, the only limitation being radiation damage. We review our experimental results, discuss the fundamental limits of this technique and future plans.Comment: 7 pages, 8 figure