Action dichroism in perception of vectorial photo-excitation in the solar-tracking leaf ofLavatera cretica L.

The leaf lamina ofLavatera cretica L. exhibits a diaphototropic response that discriminates between two opposite, constant vectorial excitations by white light beams whose fluence rates differ by as little as 10% (50 versus 45 μmol·m⁻²·S⁻¹). The relationship between the response (angular velocity of laminar reorientation) and the fluence-rate ratio is linear. The lamina similarly discriminates between two such excitations by polarized light, one with the electrical vector transverse to the plane of the two beams (θ) and the opposite one with the vector parallel to that plane (⪙). When two such beams were of equal fluence rate, the lamina reoriented towards the ⪙ beam. When the fluence rate of the θ beam was maintained at 50 μmol·m⁻²·s⁻¹ and that of the ⪙ beam was reduced, the response to the latter (angular velocity of laminar reorientation) was reduced progressively. Further reduction in the fluence rate of the ⪙ polarized beam eventually resulted in reorientation in the opposite direction (towards the θ beam) and the response to the latter increased progressively with the reduction in fluence rate. The equilibrium was at a ⪙/θ ratio of 0.62. Measurements of reflectance of oblique beams of ⪙ and θ polarized light from the upper laminar surface, and of transmittance of such light ghrough the lamina, eliminated the possibility that optical dichroism of the lamina contributed significantly to these results. The implications of this action dichroism to the postulated mechanism of perception of vectorial excitation by these leaves is discussed. Dedicated to the 60thbirth day of Professor Hans Mohr     

Myo-inositol oxygenase from oat seedlings

Summary Enzyme preparations from oat seedlings showing the activity ofmyo-inositol oxygenase (E.C.1.13.99.1) have been described previously. In contrast tomyo-inositol oxygenase preparations from other sources, e.g. rat kidney or yeast, the oat enzyme seemed to exhibit a somewhat less stringent activity, acting on other inositols and inositol methyl ethers as well as onmyo-inositol.By purification of the enzyme present in the extract from oat seedlings with the help of an affinity gel specific for enzymes acting onmyo-inositol a homogeneous enzyme preparation was obtained, which shows the same strict specificity as themyo-inositol oxygenase from other sources. It has a molecular weight of 62,000 and tends to aggregate to oligomers (up to tetramers) under physiological pH-values; in more alkaline media dissociation to monomers is observed. The action on the other inositols and inositol methyl ethers is apparently due to one or more other enzymes, which are also adsorbed on the affinity gel, but can be separated from themyo-inositol oxygenase by elution with increasing concentrations ofmyo-inositol.Dedicated to Professor Karl KRATZL on the occasion of his 60th birthday.     

Ethylene and the geotropic response of lateral branches in peanuts (Arachis hypogaea L.)

The prostrate growth habit of runner-type peanut plants changedwhen treated with the ethylene-releasing compound CEPA: thehorizontal branches became plagiotropically oriented and theplant assumed a bushy form. Treatment with CEPA caused a markedincrease in ethylene evolution for about a week, which thendecreased to the level of the control. Nevertheless, the branchesmaintained their newly assumed plagiotropic orientation. Ethylene evolution from isolated branch tips correlated withtheir age and orientation, being highest in old plagiotropicand lowest in old diatropic branches. Light intensity and qualitywhich caused plagiotropic orientation of branches also causedan increase in ethylene evolution, while ethylene evolutionwas lowest under light conditions favouring diatropic orientation.Along with the changes to plagiotropic orientation by CEPA,an increase in GA-like substances and a decrease in growth inhibitorswas observed in extracts from treated plants. (Received October 7, 1975; )     

Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review

ObjectiveTo summarise the evidence on accuracy of the Ottawa ankle rules, a decision aid for excluding fractures of the ankle and mid-foot.DesignSystematic review.Results32 studies met the inclusion criteria and 27 studies reporting on 15 581 patients were used for meta-analysis. The pooled negative likelihood ratios for the ankle and mid-foot were 0.08 (95% confidence interval 0.03 to 0.18) and 0.08 (0.03 to 0.20), respectively. The pooled negative likelihood ratio for both regions in children was 0.07 (0.03 to 0.18). Applying these ratios to a 15% prevalence of fracture gave a less than 1.4% probability of actual fracture in these subgroups.ConclusionEvidence supports the Ottawa ankle rules as an accurate instrument for excluding fractures of the ankle and mid-foot. The instrument has a sensitivity of almost 100% and a modest specificity, and its use should reduce the number of unnecessary radiographs by 30-40%.

What is already known on this topic

Although most patients with ankle sprains who present to emergency departments undergo radiography, less than 15% have a fractureThe Ottawa ankle rules is a clinical decision aid designed to avoid unnecessary radiography

What this paper adds

The Ottawa ankle rules is highly accurate at excluding ankle fractures after sprain injury     

Biliproteidkomposition und Pigmentverteilung in scheibchenförmigen Phycobilisomen von Rhodella violacea

Ein Modell der Anordnung von Phycoerythrin, Phycocyanin und Allophycocyanin in den scheibchenförmigen Phycobilisomen von Rhodella violacea wird vorgestellt; es steht in Einklang mit der quantitativen und qualitativen Pigmentkomposition, dem intermolekularen Energietransfer sowie der Feinstruktur isolierter Phycobilisomen. Hohe Lichtintensitäten und sechstägiger Nitratmangel führen zu einer Reduktion des gesamten Biliproteidgehalts der Zellen. Darüber hinaus ist eine Veränderung der Pigmentkomposition der isolierten Phycobilisomen nachweisbar. Der Phycocyanin- und der Allophycocyaningehalt sind davon unberührt, während der Phycoerythrinanteil auf wenigstens 78% verringert wird. Der Verlust von zwei bis drei Phycoerythrinaggregaten je Phycobilisom beeinträchtigt weder die Fähigkeit zum Energietransfer noch die Fluoreszenzausbeute bei 665 nm in Suspensionen gleichen Phycocyanin- und Allophycocyaningehalts. Wir danken der Deutschen Forschungsgemeinschaft (SFB 103) für die finanzielle Unterstützung.     

A chloroplast DNA of Euglena gracilis with five complete rRNA operons and two extra 16S rRNA genes

Summary DNA was isolated from chloroplasts of Euglena gracilis var. bacillaris (ATCC No. 10616). The structure of the rDNA was studied using partial denaturation mapping and heteroduplex analysis. Seven GC-rich stretches representing the rDNA were apparent in the partial denaturation pattern. To analyse the structure of the rDNA in detail, heteroduplexes with the E. coli rrnD operon cloned in the plasmid pBK8 were prepared. Five complete rRNA operons were found. In addition one extra 16S rRNA gene was located between the second and third complete operons and another extra 16S rRNA gene was upstream of all five operons. Each one was associated with a small inverted repeat structure.