Grenzen der Kompensation: Energiebudgets von Ringelg?nsen (Branta b. bernicla) — die Wirkung von St?rreizen

Zusammenfassung Der Einfluß von Störreizen auf das Energiebudget von Ringelgänsen wurde im Frühjahr 1991 in zwei Vorland-Salzwiesen des Nationalparks Schleswig-Holsteinisches Wattenmeer vergleichend untersucht. Die Häufigkeit störreizbedingter Reaktionen der Gänse (Störreizhäufigkeit) wurde als Index für die anthropogene Beeinflussung der Gebiete herangezogen. Die Beeinflussung war in Westerhever mit 1,5±0,7 Reaktionen/h signifikant größer als vor dem Norderheverkoog (1,0±0,6 Reaktionen/h). Mit zunehmender Aktivitätszeit wurde in beiden Gebieten im Verlauf des Frühjahres mehr umsetzbare Energie aufgenommen. In Westerhever haben die Gänse im Vergleich zu denen vor dem Norderheverkoog mit Ausnahme des Mai jeweils mehr umsetzbare Energie aufgenommen. Die energetischen Kosten (DEE) der Gänse wurden anhand der Zeit-Energie-Budget Methode und über die gemessene Körpermasseentwicklung von Fänglingen berechnet. Beide Methoden erzielten vergleichbare Ergebnisse; die Unterschiede betrugen je nach Gebiet 0,4 bis 4,5 %. In Westerhever verzeichneten die Gänse im Vergleich zu denen vor dem Norderheverkoog im Monatsmittel höhere energetische Kosten. Aus dem budgetierten Energieüberschuß (E) wurde die theoretisch mögliche Reservestoffanlagerung (Änderung der Körpermasse) der Gänse berechnet. In Westerhever konnten die Gänse im Verlauf des Frühjahres 357 g Körperreserven anlagern. Bei den Gänsen vor dem Norderheverkoog waren es 399 g. Der Unterschied betrug 11,7 %, war aber nicht signifikant. Anhand von Fangdaten ist bekannt, daß Ringelgänse im langjährigen Mittel Körperreserven von 380 bis 400 Gramm anlagern. Die Störreizhäufigkeit des Tages bewirkte eine signifikante Veränderung der Budgetparameter DME und DEE und E auf stündlicher Basis. In Westerhever stieg die Aufnahme an umsetzbarer Energie signifikant mit steigender Störreizhäufigkeit an. Vor dem Norderheverkoog verringerte sich diese jedoch signifikant. Die Energieaufwendungen stiegen in beiden Gebieten signifikant mit steigender Reizhäufigkeit an. Der Überschuß in der Energiebilanz der Gänse in Westerhever war an Tagen mit einer großen Störreizhäufigkeit um 8,7 % gegenüber den Tagen mit einer geringen Reizhäufigkeit verringert. Aufgrund fehlender kompensatorischer Nahrungsaufnahme war der Überschuß bei den Gänsen vor dem Norderheverkoog um maximal 27,5 % vermindert. Die Gänse in Westerhever haben störreizbedingte Zeitverluste bei der Nahrungsaufnahme und erhöhte energetische Kosten durch Verhaltensänderung und eine erhöhte Nahrungsaufnahme pro Zeit kompensiert. Aufgrund physiologischer Zwänge sind sie jedoch in dem stark vom Menschen beeinflußten Gebiet an die Grenzen ihrer Kompensationsmöglichkeit angelangt. Die errechnete Reservestoffanlagerung und auch der Jungvogelanteil im nachfolgenden Herbst waren geringer als bei den Gänsen vor dem Norderheverkoog.

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Compensatory limits: energy budgets of Brent Geese,Branta b. bernicla, the influence of human disturbance

The impact of human disturbances on the energy budget of Brent Geese,Branta b. bernicla, during spring migration was investigated in two different salt marsh areas within the national park Schleswig-Holsteinisches Wattenmeer, Germany. We used the frequency of disturbance-related reactions of the birds as an indicator of the anthropogenic influencing of the sites. The disturbance frequency was significantly higher in the Westerhever salt marsh (1,5±0,7 reactions/h) than in the Norderheverkoog area (1,0±0,6 reactions/h). Monthly activity and energy budgets of the birds were calculated from March to May, based on several simultaneous day-round field observations per month. The amount of daily metabolizable energy (DME) was calculated via dropping rate and digestability of the food. The daily energy expenditure (DEE) was calculated by means of the time-energy-budget methods and by calculations, using the bodymass changes of caught birds during spring. With both methods very similar results were obtained; they varied between 0,4 to 4,5 % per areas and month. The daily energy budget (Æ E) was calculated from DEE — DME. Due to an increasing daily activity time from March to Mai the DME increased in both areas. Compared to the Norderheverkoog area the DME of the birds in Westerhever was higher in March and April, and similar in Mai. DEE increased in both areas too and was in all months higher in Westerhever than in Norderheverkoog. The calculated bodymass changes of the birds during spring was 357 g for the birds in Westerhever and 399 g for the birds in Norderheverkoog. Bodymass measures from caught birds revealed a mean mass gain of 380 to 400 g during spring. The daily disturbance frequency caused a significant change in the budget parameters DME, DDE and E on a hourly base. In Westerhever DME/h increased, while in Norderheverkoog DME/h decreased significantly with increasing disturbance frequency. At the same time DEE/h increased in both areas significantly. As a consequence E/h was reduced at days with a high disturbance frequency; in Westerhever by 8,7 % and in Norderheverkoog by 27,5%. In the disturbed area the birds compensated the time-loss during feeding and the higher energetic costs during disturbance-related flights by a change in activity pattern and by an increased food consumption per time unit. Based on physiological constraints the birds reached their compensatory abilities. The calculated bodymass gain and the proportion of young birds in the flocks was reduced in autumn.

     

Occupational injuries,illness affect 1 in 13 Canadians.

One in every 13 Canadian workers has experienced a work-related illness or injury, federal data indicate. Occupational-health clinics in Ontario report a growing number of cases of sick-building syndrome, repetitive-strain injury, asthma and chemical exposure, as well as injuries related to the use of construction equipment. In the past the medical profession assumed that men incurred most work-related injuries, but today, says an occupational-health specialist, "work-related illness and injuries are just as likely to happen to women or to white-collar professionals."     

Automata,repeated games and noise

We consider two-state automata playing repeatedly the Prisoner's Dilemma (or any other 2 × 2-game). The 16 × 16-payoff matrix is computed for the limiting case of a vanishingly small noise term affecting the interaction. Some results concerning the evolution of populations of automata under the action of selection are obtained. The special role of win-stay, lose-shift-strategies is examined.     

Methane monooxygenase mutants of Methylosinus trichosporium constructed by marker-exchange mutagenesis

Abstract Methylosinus trichosporium OB3b synthesizes a soluble cytoplasmic methane monooxygenase when grown in copper-depleted medium and a membrane-bound particulate methane monooxygenase under copper-replete conditions. The genes encoding the hydroxylase component of soluble methane monooxygenase, carried on a plasmid in Escherichia coli , were insertionally inactivated using a kanamycin cassette and transferred back into M. trichosporium by conjugation. Marker-exchange mutagenesis, via a double homologous recombination event, yielded a soluble methane monooxygenase-negative mutant which grew only on methane using the particulate methane monooxygenase during copper-replete growth conditions, thus proving that the two methane oxidation systems in this methanotroph are genetically distinct.     

On the measurement of shapes

We are here concerned with the functionf which assigns to each pointP of an object the numberf(P) which is the shortest distance fromP to the border. This function appears in various guises in diverse biological studies. The functionf(P) is itself a measure of shape—or more precisely, an infinite set of measures, one for each point (and hence, in view of its geometric definition, usually in a form inconvenient for use). Thus in this paper we sought a reasonable representative of this infinite set of measures, namely themean of the numbersf(P) asP ranges over all points of the entity. Computability studies are developed for various classes of shapes. For example, (1) the mean for a lamina bounded by a polygon circumscribable about a circle of radiusr isr/3; (2) the mean for a domain bounded by a polyhedron circumscribable about a sphere of radiusr isr/4. The transition from pointwise to piecewisef(P), especially in the non-convex case, requires working with inequalities.     

The nutritional ecology of larvae of Alsophila pometaria and Anisota senatoria feeding on early- and late-season oak foliage

The larvae of Alsophila pometaria (Harr.), feeding on the young foliage of oak, has a higher relative growth rate (RGR) and relative nitrogen accumulation rate (RNAR) than the larvae of Anisota senatoria (J. E. Smith), feeding on the mature foliage of oak. Although the young oak foliage is more efficiently digested by A. pometaria (higher AD's), it is not more efficiently assimilated and used for growth (no difference in ECI's). Thus, the higher growth rate of A. pometaria is due entirely to a higher consumption rate (RCR and RNCR). Young foliage is significantly higher in nitrogen and water than mature foliage, but phenol and tannin levels are comparable in young and old foliage. A. pometaria consumes the foliage of different oak species at the same rate, independent of nitrogen content, while A. senatoria increases its consumption rate in response to decreased nitrogen levels. As a result, the growth rate of A. pometaria is directly related to leaf nitrogen content, while the growth rate of A. senatoria is independent of leaf nitrogen. The two species of insects have digestive systems that are very similar biochemically, and that are well-designed for effective protein digestion. Tannins and phenols do not influence the nutrional indices of either species. We suggest that the major benefit of spring feeding is the availability of succulent, high-nitrogen foliage, and not the avoidance of high-tannin foliage. The spring feeder appears to have a feeding strategy that favors rapid growth at the expense of efficiency, while the late summer feeder has a strategy that favors efficiency over rate.

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Résumé Alimentées sur feuillage jeune de chêne, les chenilles d'Alsophila pometaria avaient un taux relatif de croissance (RGR) et un taux relatif d'accumulation d'azote (RNAR) plus élevés que les chenilles d'Anisota senatoria alimentées sur feuillage mûr de chêne. Bien que le jeune feuillage soit plus efficacement digéré par A. pometaria (AD plus élevé), il n'est pas assimilé et utilisé pour la croissance avec de meilleurs rendements (les ECI ne sont pas différents). Ainsi le taux de croissance plus élevé d'A. pometaria est dû entièrement à un taux de consommation plus important (RCR et RNCR). Le feuillage jeune est significativement plus riche en azote et en eau que le feuillage mûr, mais les niveaux de phénol et de tanins sont les mêmes. A pometaria consomme les feuilles de différentes espèces de chênes au même taux, indépendamment de la teneur en azote, tandis que A. senatoria accroît sa consommation en réponse à une diminution de la teneur en azote. Il en résulte que le taux de croissance d'A. pometaria dépend directement de la teneur en azote des feuilles, tandis que celui d'A. senatoria en est indépendant. Les systèmes digestifs des deux insectes sont biochimiquement semblables et sont efficaces pour la digestion des protéines. Les tanins et les phénols n'influent pas sur les indices nutritionnels de ces deux espèces. Nous estimons que le principal intérêt de l'alimentation printanière est la disponibilité en feuillage succulent, riche en azote, et non l'absence de feuilles à haute teneur en tanin. L'alimentation printanière semble correspondre à une strategie alimentaire qui favorise la croissance aux dépens de l'efficacité tandis que l'alimentation en fin d'été est une stratégie qui favorise l'efficacité sur la rapidité.

     

Selective activation of cyclic AMP dependent protein kinase by calcitonin in a calcitonin secreting lung cancer cell line

When the F1-ATPase from the thermophilic bacterium, PS3, was inactivated by 90% with 7-chloro-4-nitro[14C]benzofurazan ([14C]Nbf-Cl) at pH 7.3 and then gel-filtered, 1.25 mols of [14C]Nbf-O-Tyr and less than 0.1 mol of Nbf-N-Lys were formed per mol of enzyme. After adjusting the pH of the gel-filtered, modified enzyme to 9.0 and incubating it for 14 hrs. at 23 degrees C to promote O----N migration, 0.68 mol of Nbf-N-Lys were formed per mol of enzyme while about 16% of the original activity reappeared. Isolation of the subunits after the O----N migration showed that 90% of the incorporated 14C was present in the beta subunit, which contained 0.21 mols of [14C]Nbf-N-Lys per mol. A tryptic peptide which contained the majority of the 14C incorporated into the beta subunit was isolated and subjected to automatic amino acid sequence analysis contained 38 residues. The amino acid sequence immediately around the lysine residue labeled with [14C]Nbf-, K*, was found to be: ...I-G-L-F-G-G-A-G-V-G-K*-T-V-L-I-G... .     

Photosynthetic electron transport in guard cells of diverse species

Guard cells of plants representing 18 species were assayed qualitatively for potential to conduct photosynthetic linear electron transport. These plants included C₃ pteridophytes, C₃ and C₄ monocots, and C₃, C₄, and Crassulacean acid metabolism dicots. By use of a microfluorospectrophotometer, guard cell samples in epidermal peels were isolated optically. Chlorophyll fluorescence was monitored from the onset of excitation light. For guard cells of all these species, fluorescence intensity increased during illumination. When samples were preincubated with 3-(3,4-dichlorophenyl)-1,1-dimethylurea, diuron, however, there was a more rapid increase in fluorescence. These results indicate that all tested guard cells conduct photosynthetic electron transport through the reaction center of photosystem II.     

Changes in intracellular proteolysis in Escherichia coli during prolonged growth with a low concentration of dihydrostreptomycin

Abstract Escherichia coli was cultured with a low concentration of dihydrostreptomycin (2.5 μg/ml.). Growth was similar to untreated controls for 10 h after which a slow decline in growth rate occurred; growth ceased after 20 h. Intracellular catabolism of pulse-labelled protein synthesised at various points during the antibiotic treatment increased during the first 10 h, but during the second 10 h proteolysis progressively declined to almost control values. The production of an aberrant proteolytic system is one possible explanation.