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  • Springer  (118)
  • American Geophysical Union  (20)
  • 2005-2009  (60)
  • 1985-1989  (78)
  • 1940-1944
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  • 11
    Electronic Resource
    Electronic Resource
    Foraging behavior of cackling Canada Goose goslings: implications for the roles of food availability and processing rate (1988)
    Springer
    Oecologia 75 (1988), S. 119-124 
    Details
    ISSN: 1432-1939
    Keywords: Canada Goose ; Digestion ; Foraging ; Grazing ; Tundra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Time spent foraging (and in other activities), rate of pecking at food items and length of foraging and nonforaging periods were studied in cackling Canada goose (Branta canadensis minima) goslings during brood-rearing on the Yukon-Kuskokwim Delta, Alaska in 1978 and 1979. Brood density on the study area was twice as high in 1978 (23 broods) as in 1979 (12 broods) owing in part to annual variation in nesting density and success. Peck-rates were lower in meadows during 1978 than in 1979. There was no between-year difference in time spent foraging prior to the adult molt (59% of daylight hours) but during molt, goslings spent more time feeding in 1978 (70%) than in 1979 (56%). Prior to the adult molt, 12.2 and 11.9 hours were spent feeding each day in 1978 and 1979 respectively, whereas goslings fed for 13.4 and 10.6 hours daily, in the two years during molting and fledging. Increased foraging time during the molt in 1978 completely compensated for lower peck rates so that total number of pecks per day during this period were similar in 1978 (62,800 pecks/d) and 1979 (57,900 pecks/d). Elsewhere, we reported that cackling geese significantly reduced the availability of their preferred food in 1979 and this food comprised a smaller proportion of the diet in 1978 than 1979. This variation in diet suggests that preferred foods were less available at higher brood densities, resulting in annual variation in foraging behavior. Lengths of foraging periods increased during brood-rearing in both years but were longer on average in 1978. There was no seasonal or between year variation in the length of nonforaging periods. The alternating pattern of foraging and nonforaging periods suggests that rate of processing limits rate of food intake because a relatively constant period of time was regularly required to empty the esophagus before foraging could be resumed. The restriction of food intake by digestive processes increased the importance of dietary nutrient concentrations because low nutrient concentrations could not be compensated for by higher rates of food intake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378824
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  • 12
    Electronic Resource
    Electronic Resource
    Plant stress and insect behavior: cottonwood, ozone and the feeding and oviposition preference of a beetle (1988)
    Springer
    Oecologia 76 (1988), S. 51-56 
    Details
    ISSN: 1432-1939
    Keywords: Plagiodera versicolora ; Populus deltoides ; Clones ; Damage distribution ; Community structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adults and larvae of the beetle Plagiodera versicolora preferred to feed on and consumed more of cottonwood, Populus deltoides, plant material that had been previously exposed to an acute dose of ozone (0.20 ppm, 5 h), compared to controls in choice experiments. However, females preferred to oviposit on the unexposed controls. Results were consistent for 2 cottonwood clones over 3 years in disc, leaf and whole-plant choice tests. The differential feeding and oviposition response of this insect to stressed plants could have at least 3 unexpected consequences: 1. An immediate increase in damage to stressed trees, but a subsequent decrease in damage. 2. A subsequent increase in damage to unstressed adjacent trees. 3. Changes in the insect and pathogen communities of both stressed and unstressed trees. These complex scenarios show that predicting outcomes of plant stress on plant-insect interactions will require comprchensive examination of behavioral, growth and reproductive responses of insects to stressed plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379599
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  • 13
    Electronic Resource
    Electronic Resource
    Pseudocopulation of an orchid by male ants: a test of two hypotheses accounting for the rarity of ant pollination (1987)
    Springer
    Oecologia 73 (1987), S. 522-524 
    Details
    ISSN: 1432-1939
    Keywords: Ant pollination ; Orchid ; Pseudocopulation ; Metapleural gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The orchid Leporella fimbriata is pollinated by pseudocopulation with winged males of the ant Myrmecia urens. This recently studied interaction provides a unique opportunity to examine the two current hypotheses concerning the apparent rarity of ant pollination systems worldwide. The first hypothesis requires a series of specialized growth forms and floral characteristics regarded as adaptations to ant pollination. L. fimbriata does not possess them. The second considers the pollenicidal effects of secretions from the metapleural gland of ants. These glands are absent in M. urens males and it may be that the occurrence of ant pollination requires the absence of metapleural glands in the vector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379410
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  • 14
    Electronic Resource
    Electronic Resource
    Temporal variation of mineralogy and petrology in cognate gabbroic enclaves at Arenal volcano, Costa Rica (1989)
    Springer
    Contributions to mineralogy and petrology 103 (1989), S. 110-122 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Gabbroic enclaves ejected during the current eruption phase (A-1) and during the latest prehistoric eruption phase (A-2) of Arenal Volcano show systematic variations in texture, mineralogy and composition as a function of host rock chemistry and timing of eruption. The most differentiated enclaves occur in the more differentiated A-2 lavas. Enclaves in the A-1 volcanics are consistently less evolved. Within the current A-1 eruption, the most mafic enclaves are amphibole-bearing rocks that were erupted during the first 2–3 years of activity (1968–1970). These enclaves occur in the most differentiated A-1 volcanics and are not in equilibrium with their host rocks. They crystallized from a hydrous melt that was slightly more mafic than anything erupted during the current cycle. We interpret the enclaves as sidewall crystallization products of a melt, possibly a high-alumina basalt, that was immediately parental to the A-1 lavas. Enclaves that occur in A-1 rocks erupted after 1970 and all of the A-2 enclaves are amphibole-free and less mafic than the early A-1 enclaves. Their chemistry suggests that they formed during the early to intermediate crystallization of their host lavas. None of the enclaves contain minerals that might have equilibrated with a primary, mantle-derived melt. Geothermometry is consistent with geochemistry, with amphibole-bearing A-1 enclaves yielding the highest pyroxene temperatures (ave. 1090° C) and A-2 enclaves the lowest (ave. 1030° C). Geobarometry suggests mid- to upper crustal depths for the crystallization of all enclaves. The enclaves are cognate and reflect pre-eruptive crystallization of Arenal magmas. They record evolution from a hydrous, basaltic magma to the drier basaltic andesites that characterize the current eruption. Volatiles appear to have been lost due to depressurization during the slow ascent of the magmas through the upper levels of the crust following the initial explosive eruption. Volatile loss and depressurization resulted in the destabilization and the progressive resorption of amphibole. The A-2 lavas may represent the long-term fractionation products of basaltic andesite magmas similar in composition to the A-1 lavas. Anorthitic plagioclase, commonly thought of as a phase stabilized by high Ca/Na and high water pressure, continued to crystallize in a system with relatively low Ca/Na and which had dehydrated and/or depressurized to the point at which amphibole was no longer stable. This suggests that compositional characteristics other than high Ca/Na or high water content may have stabilized the anorthite in the basaltic and basaltic andesite melts at Arenal. We speculate that the high-alumina content of the Arenal magmas may be the stabilizing factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371368
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  • 15
    Electronic Resource
    Electronic Resource
    A method to create simplified versions of existing habitat suitability index (HSI) models (1988)
    Springer
    Environmental management 12 (1988), S. 79-83 
    Details
    ISSN: 1432-1009
    Keywords: Habitat evaluation procedures ; Habitat quality ; Habitat suitability index models ; Impact assessment ; Wildlife management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The habitat evaluation procedures (HEP), developed by the US Fish and Wildlife Service, are widely used in the United States to determine the impacts of major construction projects on fish and wildlife habitats. HEP relies heavily on habitat suitability index (HSI) models that use measurements of important habitat characteristics to rate habitat quality for a species on a scale of 0 (unsuitable) to 1.0 (optimal). This report describes a method to simplify existing HSI models to reduce the time and expense involved in sampling habitat variables. Simplified models for three species produced HSI values within 0.2 of those predicted by the original models 90% of the time. Simplified models are particularly useful for rapid habitat inventories and evaluations, wildlife management, and impact assessments in extensive areas or with limited time and personnel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01867379
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  • 16
    Electronic Resource
    Electronic Resource
    Industry and the environment: Chief executive officer attitudes, 1976 and 1986 (1989)
    Springer
    Environmental management 13 (1989), S. 243-249 
    Details
    ISSN: 1432-1009
    Keywords: Environmental values ; Executive attitudes ; Pollution management ; Attitudinal shifts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This research considers the question of changing environmental values within the leadership of firms responsible for the management of pollution as an unwanted byproduct. Information was obtained from a pair of surveys mailed to the chief executive officers (CEOs) of the 50 largest firms listed within the mining and manufacturing directories of Colorado, Montana, Utah, and Wyoming in 1976 and again in 1986. The authors found that industry CEOs were more supportive of environmental concerns in 1986 than 1976, suggesting that ecological values have become institutionalized to some extent. Yet, there is little indication that this attitudinal shift in environmental concern among CEOs has been accompanied by a willingness to spend a larger proportion of the company budget on pollution control or to improve working relationships with federal regulatory officials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868371
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  • 17
    Electronic Resource
    Electronic Resource
    The origin of mutant cells: mechanisms by whichSaccharomyces cerevisiae produces cells homoplasmic for new mitochondrial mutations (1985)
    Springer
    Current genetics 9 (1985), S. 627-640 
    Details
    ISSN: 1432-0983
    Keywords: Mitochondria ; Mutation ; Yeast ; Selection ; Random drift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Haploid yeast cells have about 50 copies of the mitochondrial genome, and a mutational event is unlikely to affect more than one of these at a time. This raises the question of how such cells, or their progeny, become fixed (homoplasmic) for the mutant alele. We have tested the roles of six hypothetical mechanisms in producing erythromycin-resistant mutant cells: (i) random partitioning of mitochondrial genomes at cell division; (ii) intracellular selection for mtDNA molecules of one genotype; (iii) intracellular random drift of mitochondrial allele frequencies; (iv) intercellular selection for cells of a particular mitochondrial genotype; (v) induction of mitochondrial gene mutations by the antibiotic used to select mutants; and (vi) reduction in the number of mitochondrial genomes per cell by the antibiotic. Our experiments indicate that intracellular selection plays the major role in producing erythromycin-resistant mutant cells in the presence of the antibiotic. In the absence of the antibiotic, the combined effects of random drift and random partitioning are most important in determining the fate of new mutations, most of which are lost rather than fixed. Our experiments provide no evidence for mutation induction or ploidy reduction by erythromycin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00449815
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  • 18
    Electronic Resource
    Electronic Resource
    E.p.r. and spectroscopic studies of configurational changes in 1,4-diazacycloheptane copper(II) complexes (1987)
    Springer
    Transition metal chemistry 12 (1987), S. 214-218 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary E.p.r. and spectroscopic studies of bis(1,4-diazacycloheptane)copper(II) perchlorate, bromobis(1,4-diazacycloheptane)copper(II) perchlorate and dibromo-bis(1,4-diazacycloheptane)copper(II), were carried out in MeNO2, DMSO and H2O solutions as well as in the polycrystalline state. The ligation of bromide ion to bis(1,4-diazacycloheptane)copper(II) along thez-axis was investigated. The e.p.r. spectra are explained in terms of energy changes involving the electronic ground state and the lowest excited state as a function of ligation of nucleophiles to the metal atom along thez-axis. In the polycrystalline state, the weaker the apical interaction (square-planar species) the lower theg-value and the higher the copper(II) hyperfine coupling constant. In the liquid state, theg-values observed in non-coordinating solvents such as MeNO2 are similar to those for the polycrystalline material suggesting structural similarity in the two states. The electronic absorption maxima for the three complexes in the liquid state shift to higher energy with an increase in tetragonal distortion around copper(II). In strongly coordinating solvents the e.p.r. spectra and absorption maxima are independent of the anion present. The increasing strength of solvation results in an increase in the wavelength of the optical transition and theg-values, and a decrease in the copper(II) hyperfine coupling constant. It appears that an increase in the basicity of the solvent has the same effect on thed-orbital energy levels and on the unpaired electron density on copper(II)_as does increasing the electronegativity of the substituents on the ligand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023533
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  • 19
    Electronic Resource
    Electronic Resource
    An improved method for the isolation of rat cardiac sarcoplasmic reticulum (1988)
    Springer
    Molecular and cellular biochemistry 84 (1988), S. 87-95 
    Details
    ISSN: 1573-4919
    Keywords: rat ; cardiac sarcoplasmic reticulum ; Ca2+-ATPase ; calsequestrin ; 53 kD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Preparations of cardiac sarcoplasmic reticulum (CSR) isolated from the rat by differential centrifugation have been widely used for measuring alterations in intracellular calcium flux in response to metabolic and pharmacologic disruptions. However, the purity of these SR fractions has not been firmly established. Using a combination of differential and linear sucrose gradient centrifugation, we have isolated rat CSR with high specific activity and purity. By SDS-PAGE analysis, the preparation is enriched in a protein (110 kD) of similar size to the Ca2+-ATPase of SR from other sources. Gels stained with the dye ‘Stains All’ reveal a blue colored 55 kD band, confirming the presence of calsequestrin, the intraluminal low-affinity calcium binding protein of SR. The presence of the transmembrane 53 kD glycoprotein of SR was confirmed by endoglycosidase-H treatment followed by SDS-PAGE and also by a modified Western blotting technique. The rate of calcium uptake in this preparation averages 130 nmol/mg over the first minute of accumulation, approximately 4 times that previously reported for rat CSR. Calcium uptake in our preparation was essentially complete within 5 minutes. Preparations isolated by this method should be of value in future studies measuring alterations in rat CSR function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235196
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  • 20
    Electronic Resource
    Electronic Resource
    Influence of exercise on cardiac and skeletal muscle myofibrillar proteins (1988)
    Springer
    Molecular and cellular biochemistry 83 (1988), S. 27-36 
    Details
    ISSN: 1573-4919
    Keywords: fatigue ; myofibril ATPase ; Ca2+ regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The purpose of this study was to examine the Ca2+-Mg2+ myofibrillar ATPase and protein composition of cardiac and skeletal muscle following strenuous activity to voluntary exhaustion. Sprague-Dawley rats (200 g) were assigned to a control and exercised group, with the run group completing 25 m·min−1 and 8% grade for 1 hour. Following activity, the myocardial Ca2+−Mg2+ myofibrillar ATPase activity -pCa relationship had undergone a rightward shift in the curve. Electrophoretic analysis revealed a change in the pattern of cardiac myofibrillar protein bands, particularly in the 38–42 Kdalton region. Enzymatic analysis of myofibrillar proteins from plantaris muscle, revealed no change in Ca2+ regulation following exercise. Electronmicrographic and electrophoretic analysis revealed extensively disrupted sarcomeric structure and a change in the ratio of several plantaris myofibrillar proteins. No difference was observed for myosin: Actin: tropomyosin ratios; however a dramatic reduction in 58 and 95 Kdalton proteins were evident. The results indicate that prolonged running is associated with similar responses in cardiac and skeletal muscle myofibrillar protein compositions. The abnormalities in myofibrillar ultrastructure may implicate force transmission failure as a factor in exercised-induced muscle damage and/or fatigue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223195
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