Is a differentiated advice by season and region necessary?

The ultraviolet radiation component in the solar spectrum varies greatly with season. In the summer, the significant short-wavelength (UV-B) radiation at midday can produce erythema in sensitive skin in less than 20 min in middle latitudes, and yet in winter months, the same midday exposure dose would require hours of exposure. The challenge for public health authorities is to provide simple, understandable messages for sensitive individuals to limit excessive exposure at appropriate times of the day during spring and summer months and yet not to take needless precautions or limit exposure during fall and winter months at mid and circumpolar latitudes. The appropriate exposure for beneficial effects is not possible to achieve at many latitudes during winter months, but is readily achieved in summer months. Simple messages should be tailored to the local times of day, reflecting the locale and season. One simple means to communicate the relative UV-B exposure relates to the length of one's shadow (the "Shadow Rule"). Further challenges are presented when apparently mixed messages would be justified for different skin phototypes.     

Reconstitution and alignment by a magnetic field of a β-barrel membrane protein in bicelles

A protocol is described for the reconstitution of a transmembrane β-barrel protein domain, tOmpA, into lipid bicelles. tOmpA is the largest protein to be reconstituted in bicelles to date. Its insertion does not prevent bicelles from orienting with their plane either parallel or perpendicular to the magnetic field, depending on the absence or presence of paramagnetic ions. In the latter case, tOmpA is shown to align with the axis of the β-barrel parallel to the magnetic field, i.e. perpendicular to the plane of the bilayer, an orientation conforming to that in natural membranes and favourable to structural studies by solid-state NMR. Reconstitution into bicelles may offer an interesting approach for structural studies of membrane proteins in a medium resembling a biological membrane, using either NMR or other biophysical techniques. Our data suggest that alignment in the magnetic field of membrane proteins included into bicelles may be facilitated if the protein is folded as a β-barrel structure.     

Purification and properties of a thermostable extracellular β-D-xylosidase produced by a thermotolerant Aspergillus phoenicis

A β-D-xylosidase was purified from cultures of a thermotolerant strain of Aspergillus phoenicis grown on xylan at 45°C. The enzyme was purified to homogeneity by chromatography on DEAE-cellulose and Sephadex G-100. The purified enzyme was a monomer of molecular mass 132 kDa by gel filtration and SDS-PAGE. Treatment with endoglycosidase H resulted in a protein with a molecular mass of 104 kDa. The enzyme was a glycoprotein with 43.5% carbohydrate content and exhibited a pI of 3.7. Optima of temperature and pH were 75°C and 4.0–4.5, respectively. The activity was stable at 60°C and had a K _m of 2.36 mM for p-nitrophenyl-β-D-xylopiranoside. The enzyme did not exhibit xylanase, cellulase, galactosidase or arabinosidase activities. The purified enzyme was active against natural substrates, such as xylobiose and xylotriose. Journal of Industrial Microbiology & Biotechnology (2001) 26, 156–160. Received 23 June 2000/ Accepted in revised form 29 September 2000     

Removal (and attempted removal) of material from a Hooded Vulture Necrosyrtes monachus nest by a starling and a Hooded Vulture§

Relatively little is documented about nest material theft in vultures. We used camera traps to monitor Hooded Vulture Necrosyrtes monachus nests for a year. We report camera trap photographs of a starling Lamprotornis sp. removing what appeared to be dung from an inactive Hooded Vulture nest on Cleveland Game Reserve, north-eastern South Africa, in October 2016. We also had evidence of a Hooded Vulture attempting to remove twigs from the same nest in August 2016. This behaviour is previously unrecorded in Hooded Vultures and, although seemingly rare, it represents an attempt to reduce the energetic costs of nest building in this species.     

Conformational State Distributions and Catalytically Relevant Dynamics of?a Hinge-Bending Enzyme Studied by Single-Molecule FRET and a Coarse-Grained Simulation

Over the last few decades, a view has emerged showing that multidomain enzymes are biological machines evolved to harness stochastic kicks of solvent particles into highly directional functional motions. These intrinsic motions are structurally encoded, and Nature makes use of them to catalyze chemical reactions by means of ligand-induced conformational changes and states redistribution. Such mechanisms align reactive groups for efficient chemistry and stabilize conformers most proficient for catalysis. By combining single-molecule Förster resonance energy transfer measurements with normal mode analysis and coarse-grained mesoscopic simulations, we obtained results for a hinge-bending enzyme, namely phosphoglycerate kinase (PGK), which support and extend these ideas. From single-molecule Förster resonance energy transfer, we obtained insight into the distribution of conformational states and the dynamical properties of the domains. The simulations allowed for the characterization of interdomain motions of a compact state of PGK. The data show that PGK is intrinsically a highly dynamic system sampling a wealth of conformations on timescales ranging from nanoseconds to milliseconds and above. Functional motions encoded in the fold are performed by the PGK domains already in its ligand-free form, and substrate binding is not required to enable them. Compared to other multidomain proteins, these motions are rather fast and presumably not rate-limiting in the enzymatic reaction. Ligand binding slightly readjusts the orientation of the domains and feasibly locks the protein motions along a preferential direction. In addition, the functionally relevant compact state is stabilized by the substrates, and acts as a prestate to reach active conformations by means of Brownian motions.     

Estimating position and velocity of a submerged moving object by the clawed frog Xenopus and by fish—A cybernetic approach

The lateral-line system is a unique facility of aquatic animals to locate predator, prey, or conspecifics. We present a detailed model of how the clawed frog Xenopus, or fish, can localize submerged moving objects in three dimensions by using their lateral-line system. In so doing we develop two models of a slightly different nature. First, we exploit the characteristic properties of the velocity field, such as zeros and maxima or minima, that a moving object generates at the lateral-line organs and that are directly accessible neuronally, in the context of a simplified geometry. In addition, we show that the associated neuronal model is robust with respect to noise. Though we focus on the superficial neuromasts of Xenopus the same arguments apply mutatis mutandis to the canal lateral-line system of fish. Second, we present a full-blown three-dimensional reconstruction of the source on the basis of a maximum likelihood argument.     

Induction of alkane-oxidizing andα-olefin-epoxidizing enzymes by a non-hydrocarbon in aPseudomonas

A strain ofPseudomonas aeruginosa could be induced to oxidizen-paraffins and to epoxidize-olefins by treating peptone-grown cells with 1,6-hexanediol or by growing them on this substrate. Of some related alcohols and acids investigated, only a few showed weak inducing capacities.Shell Research N.V.     

Acid secretion of parietal cells is paralleled by a redistribution of NSF and α, β-SNAPs and inhibited by tetanus toxin

Stimulation of parietal cells causes fusion of intracellular tubulovesicles with the canalicular plasma membrane thereby increasing the apical membrane area up to tenfold. The presence of the SNARE proteins synaptobrevin, syntaxin1, and SNAP25 in parietal cells and their intracellular redistribution after stimulation suggest a SNARE-mediated mechanism. Here we show that NSF and alpha, beta-SNAPs which are involved in the dissociation of the SNARE complex in neurons also occur in parietal cells exhibiting subcellular distributions similar to the ones obtained for SNARE proteins and for the H+, K(+)-ATPase. More importantly proteolytic cleavage of synaptobrevin by tetanus neurotoxin completely inhibits the cAMP-dependent increase of acid secretion further supporting the crucial role SNARE proteins play in parietal cells.     

Biochemical properties of a β-mannanase and a β-xylanase produced by Ceriporiopsis subvermispora during biopulping conditions

One mannanase and one of the three xylanases produced by Ceriporiopsis subvermispora grown on Pinus taeda wood chips were characterized. A combination of ion exchange chromatography and SDS-PAGE data revealed the existence of a high-molecular-weight mannanase of 150 kDa that was active against galactoglucomannan and xylan. Its activity was optimal at pH 4.5. The K_m value with galactoglucomannan as substrate was 0.50 mg ml^?1. One xylanase with molecular mass of 79 kDa was also purified and characterized. Its activity was optimal at 60 °C and pH 8.0. Its K_m value with birchwood xylan as substrate was 1.65 mg ml^?1. Both the mannanase and the 79 kDa xylanase displayed relatively high activity on carboxymethyl cellulose. The sensitivity of the xylanase and mannanase to various salts was evaluated. None of the tested salts inhibited the xylanase, but Mn⁺², Fe⁺³, and Cu⁺² were strong inhibitors for the mannanase.     

Interventional cardiology and general cardiology: divided by a common speciality? From George Bernard Shaw. America and England are two countries divided by a common language.

For a couple of years now, the annual meeting of the American College of Cardiology (ACC) consists of two separate meetings: the conventional ACC meeting and the SCAI-ACCi2 (Society for Cardiovascular Angiography and Interventions) meeting. The SCAI-ACCi2 meeting is specifically intended for interventional cardiologists and in order to attend the meeting one has to pay either a special entrance fee for this meeting or an additional fee to attend both meetings. Even Fellows of the ACC are not allowed into this dedicated interventional meeting (unless they pay the additional entrance fee). At the ACC.08 meeting in Chicago this year, the general cardiologist (ACC.08) could be recognised by a blue badge and the interventional cardiologist by a yellow badge (SCAI.ACCi2).     

Synthesis of hexyl α-glucoside and α-polyglucosides by a novel Microbacterium isolate

Alkyl-glucosides and alkyl-polyglucosides are the new-generation biodegradable surfactants with good emulsifying and wetting properties. The α-forms of these glucosides occur in antibiotics and also stimulate nasal absorption of many drugs. In this paper, we report the synthesis of hexyl α-glucoside and α-polyglucosides using cell-bound α-glucosidase activity of a novel strain of Microbacterium paraoxydans. A number of cell-bound glycosyl hydrolase activities were detected in the isolate with the maximum hydrolytic activity of 180 IU g^?1 dry wt cells on p-nitrophenyl-α-d-glucopyranoside. In a micro-aqueous system, at a water activity of 0.69, 1.8 g l^?1 of hexyl α-glucoside (corresponding to about 25 % yield) was synthesized by whole cells with maltose and hexanol as substrates. The concentration was enhanced to 11 g l^?1 (~60 % yield) in a biphasic system at a water content of 60 %. ¹H and ¹³C NMR spectra of the purified compound confirmed the synthesized product to be hexyl-α-d-glucopyranoside, while the presence of hexyl di- and tri-glucosides was confirmed by electrospray ionization mass spectrometry. The cell-driven synthesis makes this an extremely attractive alternative for synthesis of such compounds.     

Flower formation in the short-day plant Kalanchoë by grafting with a long-day and a short-long-day Echeveria

Flower formation was induced in the shortday plant Kalanchoë blossfeldiana Poellnitz under long-day conditions by grafting with flowering shoots of the short-long-day plant Echeveria harmsii (Rose) MacBr. and of the long-day plant Echeveria pulvoliver (E. pulvinata Rose x E. harmsii). Vegetative shoots from induced Echeveria plants failed to cause a flowering response in Kalanchoë. The presence of flowering and vegetative shoots side by side on induced Echeveria plants provides evidence for physiological chimeras in this genus.Abbreviations LD long day(s) - SD short day(s) - LDP long-day plant(s) - LSDP long-short-day plant(s) - SDP short-day plant(s) - SLDP short-long-day plant(s)     

Mechanisms of nuclear reprogramming by eggs and oocytes: a deterministic process?

Differentiated cells can be experimentally reprogrammed back to pluripotency by nuclear transfer, cell fusion or induced pluripotent stem cell technology. Nuclear transfer and cell fusion can lead to efficient reprogramming of gene expression. The egg and oocyte reprogramming process includes the exchange of somatic proteins for oocyte proteins, the post-translational modification of histones and the demethylation of DNA. These events occur in an ordered manner and on a defined timescale, indicating that reprogramming by nuclear transfer and by cell fusion rely on deterministic processes.     

Refolding of a denatured α-chymotrypsin and its smart bioconjugate by three-phase partitioning

α-Chymotrypsin inactivated with 8 M urea and 100 mM dithiothreitol could be completely reactivated by subjecting it to three-phase partitioning (TPP). TPP consisted of adding 30% w/v ammonium sulfate and t-butanol (volume equivalent to aqueous solution of denatured α-chymotrypsin) at 25°C. The activated α-chymotrypsin was recovered as an interfacial precipitate between the upper organic and lower aqueous phase. It was found that this could be extended to a thermally inactivated smart bioconjugate of α-chymotrypsin with Eudragit S-100 (a reversibly soluble–insoluble methmethacrylate). The thermally inactivated bioconjugate had to be further subjected to urea and dithiothreitol before refolding by three-phase partitioning. Ninety per cent of the activity of the bioconjugate could be recovered. The free enzyme and its bioconjugate which lost activity in the presence of 90% dioxane recovered 94 and 90% of their activities, respectively, by employing TPP. The refolded free enzyme and its bioconjugate were evaluated in terms of V_max/K_m and their fluorescence emission spectra.