Novel leukotrienes: Products formed by initial oxygenation of arachidonic acid at C-15

A preparation of human leukocytes was incubated with arachidonic acid. Two new dihydroxy acids with conjugated triene structures, were isolated and characterized as 8,15-dihydroxy-5,9,11,13-eicosatetraenoic acid (8,15-leukotriene B₄) and 14,15-dihydroxy-5,8,10,12-eicosatetraenoic acid (14,15-leukotriene B₄).     

Yield efficiency of the X-ray mutant svalöf's ‘pallas barley’

Summary Svalöf's Pallas barley is an X-ray mutant of the high-yielding Bonus barley variety. Both varieties were released by the Swedish Seed Association, Svalöf, and have gained wide distribution. Pallas barley arose as an erectoides mutant in 1947. After careful testing it was approved in 1958 as an original Swedish variety. It soon became widespread over great parts of western Europe owing to its high productivity, pronounced lodging resistance and high nitrogen utilization.Danish tests of barley varieties are recorded and published yearly. From 1958 when Pallas entered the Danish trials, and up to and including 1964, its parent Bonus barley was the official Danish standard variety. In 1965 it was replaced by Pallas barley. A careful biometrical comparison of the two varieties has been made with regard to grain yield, lodging resistance, straw height and strawproduction. In addition, the influence of increased lodging resistance on yield as well as the variance of yield and lodging have been analysed.

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Zusammenfassung Die Gerstensorte Svalöfs Pallas geht auf eine im Jahre 1947 entstandene röntgeninduzierte erectoides-Mutante der ertragreichen Sorte Bonus zurück. Beide Sorten wurden von dem Schwedischen Saatzuchtverein in Svalöf gezüchtet. Nach eingehender Prüfung wurde sie 1958 als schwedische Zuchtsorte zugelassen und erlangte durch ihre gute Ertragsfähigkeit, die wesentlich verbesserte Standfestigkeit und gute Stickstoffverwertung weite Verbreitung in großen Teilen Westeuropas.Die Ergebnisse der dänischen Gersten-Sortenprüfungen werden alljährlich veröffentlicht. 1958 wurde Pallas erstmalig in diese Versuche einbezogen, bei denen bis einschließlich 1964 ihre Ausgangssorte Bonus als offizielle Standardsorte diente. Sie wurde 1965 durch Pallas ersetzt. Beide Sorten wurden in bezug auf Ertragsfähigkeit, Standfestigkeit, Strohlänge und Strohertrag sorgfältigen biometrischen Prüfungen unterzogen, weiterhin wurden der Einfluß erhöhter Standfestigkeit auf die Ertragsfähigkeit untersucht sowie Ertrags- und Standfestigkeitsvarianzen geschätzt.

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This paper is cordially dedicated to Professor Hans Stubbe in appreciation of his pioneer research on induced mutations in cultivated plants.     

Effects of back-mounted biologgers on condition,diving and flight performance in a breeding seabird

Biologging devices are providing detailed insights into the behaviour and movement of animals in their natural environments. It is usually assumed that this method of gathering data does not impact on the behaviour observed. However, potential negative effects on birds have rarely been investigated before field-based studies are initiated. Seabirds which both fly and use pursuit diving may be particularly sensitive to increases in drag and load resulting from carrying biologging devices. We studied chick-rearing adult common guillemots Uria aalge equipped with and without back-mounted GPS tags over short deployments of a few days. Concurrently guillemots carried small leg-mounted TDR devices (time-depth recorders) providing activity data throughout. Changes in body mass and breeding success were followed for device equipped and control guillemots. At the colony level guillemots lost body mass throughout the chick-rearing period. When-equipped with the additional GPS tag, the guillemots lost mass at close to twice the rate they did when equipped with only the smaller leg-mounted TDR device. The elevated mass loss suggests an impact on energy expenditure or foraging performance. When equipped with GPS tags diving performance, time-activity budgets and daily patterns of activity were unchanged, yet dive depth distributions differed. We review studies of tag-effects in guillemots Uria sp. finding elevated mass loss and reduced chick-provisioning to be the most commonly observed effects. Less information is available for behavioural measures, and results vary between studies. In general, small tags deployed over several days appear to have small or no measurable effect on the behavioural variables commonly observed in most guillemot tagging studies. However, there may still be impacts on fitness via physiological effects and/or reduced chick-provisioning, while more detailed measures of behaviour (e.g. using accelerometery) may reveal effects on diving and flight performance.     

Selfish Genes and Plant Speciation

A key to understand the process of speciation is to uncover the genetic basis of hybrid incompatibilities. Selfish genetic elements (SGEs), DNA sequences that can spread in a population despite being associated with a fitness cost to the individual organism, make up the largest component in many plant genomes, but their role in the genetics of speciation has long been controversial. However, the realization that many organisms have evolved a variety of suppressor mechanisms that reduce the deleterious effects of SGEs has spurred renewed interest in their importance for speciation. The relationship between SGEs and their suppressors often results in strong selection on at least two interacting loci and this arms race therefore creates a situation where SGEs may give rise to hybrid dysgenesis due to Bateson–Dobzhansky–Muller incompatibilities (BDMIs). Here, I argue that examples of SGEs underlying BDMIs may be particularly common among plants compared to other taxa and that a focus on loci involved in genetic conflicts may be especially useful for workers interested in the genetics of plant speciation. I first discuss why the frequent mating system shifts and hybridization events in plants make for a specifically dynamic relationship between SGEs and plant host genomes. I then review some recent empirical observations consistent with SGE-induced speciation in plants. Lastly, I suggest some future directions to test fully the utility of this perspective.     

Computer‐aided calibration for visual estimation of vegetation cover

Question: What precision and accuracy of visual cover estimations can be achieved after repeated calibration with images of vegetation in which the true cover is known, and what factors influence the results? Methods: Digital images were created, in which the true cover of vegetation was digitally calculated. Fifteen observers made repeated estimates with immediate feedback on the true cover. The effects on precision and accuracy through time were evaluated with repeated proficiency tests. In a field trial, cover estimates, before and after calibration, were compared with point frequency data. Results: Even a short time of calibration greatly improves precision and accuracy of the estimates, and can also reduce the influence of different backgrounds, aggregation patterns and experience. Experienced observers had a stronger tendency to underestimate the cover of narrow‐leaved grasses before calibration. The field trial showed positive effects of computer‐based calibration on precision, in that it led to considerably less between‐observer variation for one of the two species groups. Conclusions: Computer‐aided calibration of vegetation cover estimation is simple, self‐explanatory and time‐efficient, and might possibly reduce biases and drifts in estimate levels over time. Such calibration can also reduce between‐observer variation in field estimates, at least for some species. However, the effects of calibration on estimations in the field must be further evaluated, especially for multilayered vegetation.     

Ecosystem effects of partial fish migration in lakes

Migration is a widespread phenomenon in many ecosystems. Most often, studies on migration have focused on how migration strategies are dependent on ecological parameters, but little attention has been paid to the top-down effect of migration on ecosystem processes. Cyprinid fish in many European lakes undergo partial migration, where a part of the population leaves the lake and enters streams for the winter. In this study, we model the effect of partial migration by fish on lower trophic levels in a lake ecosystem. Our results suggest that spring phyto- and zooplankton dynamics, including occurrences of clear-water phases, can be related to the timing and magnitude of partial migration of planktivorous fish. From our results we conclude that partial migration can influence the dynamics of lower trophic levels in the ecosystem. Furthermore, we hypothesize that partial migration may affect the stability of alternative stable states and transitions between them.     

Reversible alteration of nanosecond reduction of chlorophyll a+II in inside-out thylakoids correlated to inhibition and reconstitution of oxygen-evolving activity

The electron donation to Chl a⁺_II has been studied by measurement of absorbance changes at 824 nm under repetitive excitation conditions. For untreated inside-out thylakoids the electron donation was dominated by 35 and 220 ns kinetics. After salt-washing, both oxygen-evolution and nanosecond phases decreased drastically with corresponding increase in the microsecond time range. On addition of a purified 23 kDa protein, a restoration of the nanosecond phases up to 75% of the orginal level was obtained concomitant with a corresponding restoration of oxygen evolution. The results are consistent with a function of the 23 kDa protein at the oxidizing side of Photosystem II and that the nanosecond donation to Chl-a⁺_II is coupled to the natural path of electrons from water.     

Cost of In-Patient Care over 7 Years among Surgically and Conventionally Treated Obese Patients

Objective: Bariatric surgery improves cardiovascular risk factors and quality of life, but few studies have directly addressed the relation between obesity treatment and hospitalization costs. This prospective controlled study compares in-patient care between surgically and conventionally treated obese patients. Research Methods and Procedures: A total of 962 surgically and conventionally treated obese patients from the intervention study, Swedish Obese Subjects, were followed for 6 years. Changes in days of hospitalization and hospitalization costs were analyzed. Information on hospitalizations for each subject were obtained from the Swedish Hospital Discharge Register. Results: After 6 years, weight change was −16.7% in the surgical group and +0.9% in the control group (p < 0.0001). The cumulated hospital stay over 6 years was 23.4 days in the surgical group and 6.9 days in the control group (p < 0.0001). The average hospital cost for the surgical intervention was US$4300. Incremental costs that could be attributable to obesity surgery averaged US$1200 per year. After exclusion of hospitalizations for the surgical intervention and conditions common after bariatric surgery, there were no significant differences between the groups in number of hospital days or hospitalization costs. Discussion: Our experience from bariatric surgery indicates that average weight reductions of 16% will not reduce hospitalization costs over 6 years. Costs of bariatric surgery are limited and seem to be motivated given the marked improvements of cardiovascular risk factors, cardiac structure, and function and health-related quality of life.