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.

---

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.

     

Induction of chitinase and {beta}-1,3-glucanase activity in sunflower suspension cells in response to an elicitor from Phytophthora megasperma f. sp. glycinea (Pmg). Evidence for regulation by ethylene and 1-aminocyclopropane-1-carboxylic acid (ACC)

In heterotrophic cell suspensions of sunflower (Helianthus annuusL. cv. Spanners Allzweck) the effect of Pmg elicitor, a fungalelicitor preparation from Phytophthora megasperma f. sp. glycinea,on the induction of chitinase and ß-1,3-glucanaseactivity was studied in relation to changes in ethylene biosynthesis.Dose-response experiments with Pmg elicitor showed that theonset of the induction of intracellular chitinase and ß-1,3-glucanaseactivity coincided or followed a transient rise in ethyleneand particularly endogenous 1-aminocyclopropane-1-carboxylicacid (ACC) levels within 5 h of application. Treatment with5 µg ml^–1 elicitor stimulated ethylene and ACC levels1.6-fold and 4-fold, relative to control, respectively. Themolar ratio of ACC to ethylene changed from approximately 3:1in controls to 9:1 in treated cells. During further incubation,ethylene formation and, to a lesser degree, ACC levels declinedand the ACC/ethylene ratio increased to 56:1 in elicitor-treatedcells. On a protein basis, the activities of ß-1,3-glucanaseand chitinase increased approximately 5-fold and 8-fold, respectively,48 h after elicitor application. Additional treatment with theACC synthesis inhibitor aminoethoxyvinyiglycine (AVG) decreasedelicitor-induced enzyme activities and the levels of both ethyleneand ACC. Elicitor effects on chitinase and ß-1,3-glucanaseactivities could be fully restored when ACC was additionallyapplied. Concomitantly, the ACC/ ethylene ratio increased. Neithertreatments with ACC alone, which simultaneously increased internalACC and ethylene levels, nor treatments with AVG alone, whichsimultaneously reduced ACC and ethylene levels, could generallystimulate chitinase or ß-1,3-glucanase activitiesin the cells. It is suggested that ACC functions as a promotingfactor in the induction of chitinase and ß-1,3-glucanaseactivity triggered by Pmg elicitor and appears to reverse aninhibiting influence of ethylene. Key words: 1-Aminocyclopropane-1-carboxylic acid, chitinase, ß-1,3-glucanase, ethylene, Helianthus cellsuspension cultures, Phytophthora megasperma-elicitor     

Blood chemistry of the common marmoset (Callithrix jacchus) maintained in an indoor-outdoor environment: Primate comparisons

Blood chemistry values were collected over a three-year period from at least 10 colony-born and 24 wild-born apparently normal common marmosets. BUN, SGOT, creatinine, calcium, phosphorus, alkaline phosphatase, protein, albumin, cholesterol, triglycerides, uric and glucose values were determined. A statistical comparison of baseline values was made between wild-born, colony-born, male and female marmosets. Also the same comparison was made between common marmosets and cotton-top tamarins, white lipped tamarins and human subjects.     

The myosin filament: V. Intermediate voltage electron microscopy and optical diffraction studies of the substructure

Using a 200 kV electron microscope (JEM 200 A), thick (up to 0.4 μm) crosssections of the myosin filaments of vertebrate striated muscle were studied. It was found that: (a) with increasing section thickness the cross-sectional profiles of the shaft of the filament were increasingly more triangular and in sections 0.4 μm thick each apex of the triangle was clearly blunted. This unique cross-sectional profile is predicted by the model proposed by Pepe (1966,1967) in which 12 parallel structural units are packed to form a triangular profile with a structural unit missing at each apex of the triangle. (b) With increasing section thickness the substructure of the myosin filament was enhanced, with the best substructure visible in sections 0.2 μm to 0.3 μm thick. This strongly supports parallel alignment of structural units in the shaft of the filament as proposed by Pepe (1966,1967). (c) The substructure spacing, determined by optical diffraction from electron micrographs of cross-sections of individual myosin filaments or groups of filaments is about 4 nm. (d) The different optical diffraction patterns observed from individual myosin filaments can be explained if the projection of each structural unit in the plane of the section has an elongated profile. With a substructure spacing of 4 nm an elongated cross-sectional profile could be produced by having two myosin molecules per structural unit. Models drawn with two myosin molecules per structural unit in the model proposed by Pepe (1966,1967) gave optical diffraction patterns similar to those observed from individual filaments. (e) The different optical diffraction patterns observed from individual myosin filaments can be explained if the elongated profiles in each structural unit are similarly oriented but with the orientation changing along the length of the filament. The change in orientation per unit length of the filament must be small enough to maintain an elongated profile for the projection of the structural unit in the plane of the sections 0.3 μm thick. All of these observations and conclusions strongly support the model for the myosin filament proposed by Pepe (1966,1967).     

Food plant choices of two goldenrod beetles: Relation to plant quality

Summary The leaf beetles Trirhabda borealis and T. virgata are specialist herbivores of meadow goldenrods, Solidago spp., in central New York. Upon emergence, both larvae and adults must actively search for food plants, and must choose among the five goldenrod species (S. canadensis, S. gigantea, S. graminifolia, S. juncea and S. rugosa) that co-occur in old fields. The relationship between Trihabda foraging decisions and plant quality was examined by comparing food preferences in the field with the performance of beetles caged on each host. Trirhabda adults were highly selective in their use of food plants. Adults of T. borealis preferred a single host, S. canadensis, while T. virgata adults were most common on S. canadensis and S. gigantea. These preferences were not strictly related to variation in plant quality. In the laboratory, T. borealis performed equally well on four goldenrods (but completely failed to reproduce when fed S. graminifolia), and T. virgata performed equally well on all five hosts.Larval feeding preferences in each beetle species were broader, and were more in accord with subtle variation in plant quality. Newly-hatched T. borealis larvae readily colonized four hosts and rejected only S. graminifolia, which conferred the lowest survivorship and the slowest growth. Larvae of T. virgata accepted each host, even though growth rates were somewhat slower on S. graminifolia and S. juncea.Ontogenetic differences in host preference and host tolerance may have evolved because of the different host-finding abilities of each beetle stage. During host search, the sluggish, newly-emerged larvae may be more food-limited and accept even marginally inferior food plants. The relatively mobile adults are more discriminating and use a subset of suitable hosts. The intermingled dispersion of Solidago species in old fields results in frequent larval colonization of hosts seldom used by adults. In diverse plant communities, ultimate patterns of food plant choice can be a complex function of at least three factors: intrinisic plant quality, local plant dispersion, and the host-search abilities of the insect forager.     

The size of the extracellular space in the isolated midgut ofManduca sexta

The size of the extracellular space in the isolated midgut ofManduca sexta measured statically with labeled sucrose and with labeled inulin was 48 and 50 percent of tissue water respectively. Both labeled sulfate and labeled mannitol yielded loading spaces which approached the volume of the tissue water with increasing pulse time and are not valid markers of the extracellular space. A washout method yielded unreliable values for the sucrose and inulin spaces and its use cannot be justified using presently available midgut chamber designs. Values of the sucrose space measured statistically in this study and other studies using different Lepidopteran larvae and different perfusion chambers range from 42 to 48 percent of the tissue water. Agreement between published values of the sulfate space and these values of the sucrose space is fortuitous, the labeling pulses being short enough to yield approximately half saturation of the actual sulfate loading space.     

The prosthetic group of methylamine dehydrogenase from Pseudomonas AM1: evidence for a quinone structure

The g-value and linewidth of ESR spectra of methylamine dehydrogenase (primary-amine:(acceptor) oxidoreductase (deaminating) EC 1.4.99.-) and methanol dehydrogenase (alcohol:(acceptor) oxidoreductase, EC 1.1.99.8) are very similar. This similarity is also reflected in electron-nuclear double resonance (ENDOR) results, the coupling constants of two protons in one enzyme equalling those in the other. The presence of a third proton in the ENDOR spectrum of methylamine dehydrogenase suggests a different structure or a different kind of interaction which can be related to the finding that the resolved ROSTHETIC GROUP IS PROTEIN-BOUND. The bound prosthetic group has a high redox-potential, supporting the conclusion from the ESR and ENDOR results that it is a quinone derivative.     

Early events in neuromuscular junction formation in vitro: induction of acetylcholine receptor clusters in the postsynaptic membrane and morphology of newly formed synapses

The development of clusters of acetylcholine (ACh) receptors at newly formed synapses between embryonic chick spinal cord and muscle cells grown in vitro has been studied by iontophoretic mapping with ACh. A semi-automated technique using on-line computer analysis of ACh responses and a photographic system to record the position of each ACh application permit the rapid construction of extensive and detailed maps of ACh sensitivity. Clusters of receptors, evident as peaks of ACh sensitivity, are present on many uninnervated myotubes. The distribution of ACh sensitivity closely parallels the distribution of 125I-alpha-bungarotoxin binding sites on the same muscle cell. In all cases where individual myotubes were adequately mapped before and after synapse formation, ingrowing axons induced new clusters of receptors rather than seeking out preexisting clusters. Synapses can form at active growth cones within 3 h of nerve-muscle contact. New receptor clusters can appear beneath neurites within a few hours. Many of the uninnervated clusters on innervated myotubes disappear with time. In contrast, receptor clusters on uninnervated myotubes remain in the same location for many hours. Synaptic clusters and clusters on uninervated myotubes are stable even though individual receptors are metabolized rapidly. The morphology of several identified sites of transmitter release was examined. At the scanning EM level, synapses appeared as small, rough-surfaced varicosities with filopodia that radiated outwards over the muscle surface. One synapse was studied by transmission EM. Acetylcholinesterase and a basement lamina were present within the synaptic cleft.