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  • 1
    Electronic Resource
    Electronic Resource
    REMOVAL OF GAS NUCLEI FROM LIQUIDS AND SURFACES1 (1945)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 67 (1945), S. 156-157 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01217a505
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Overgrowth competition in encrusting bryozoan assemblages of the intertidal and infralittoral zones of Alaska (2000)
    Springer
    Marine biology 136 (2000), S. 813-822 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Almost 2000 cheilostomatid–cheilostomatid (bryozoan) interactions were recorded from 110 rocks from intertidal and infralittoral zone locations at Kodiac Island in the Alaskan Boreal–Arctic. Intraspecific interactions were unusually rare; this may have resulted from inhibition of con-specific settlement by adult colonies. In one species, rank did vary as a function of depth. The proportion of determinate-species encounter-pairings (a pairing in which one competitor/species wins all encounters) and tied outcomes (whereby neither competitor/species wins or loses but are involved in a “standoff” or mutual overgrowth) increased from the upper midlittoral to the lower infralittoral. The assemblage of bryozoans formed a clear hierarchy, with a score of 0.83 on Tanaka and Nandakumar's transitivity index. Overgrowth dominants did not monopolise the assemblage. The most abundant species were mid- or lower-ranked competitors. The identity of the competitive species had a major influence on the outcome of encounters. Zooidal height and colony growth morphology were important factors determining overall overgrowth rank. The greatest number of interaction types was recorded on medium-sized (surface area 〉300 and 〈600 cm2) rocks, and the overall diversity of intertidal species was very high compared with studies conducted elsewhere. The high interaction and species diversity recorded may both have resulted from intermediate levels of disturbance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270000253
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  • 3
    Electronic Resource
    Electronic Resource
    Seasonality of polypide recycling and sexual reproduction in some erect Antarctic bryozoans (1998)
    Springer
    Marine biology 131 (1998), S. 647-658 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonality of polypide cycling has been investigated for three species of erect bryozoans from Antarctica: Isoseculiflustra rubefacta (Kluge, 1914), Nematoflustra flagellata (Waters, 1904) and Himantozoum antarcticum (Calvet, 1905). Approximately ten colonies of each species were collected monthly by SCUBA divers over a 14 mo period during 1992/1993, and the status of each individual zooid was classified as differentiating/regenerating, active (feeding autozooids), degenerate (brown body) or sexually reproductive (ovicells present, or zooid containing a larva). Polypide cycling in all three species was distinctly seasonal. New zooids formed at the growth margin and typically contained actively feeding polypides for ≃9 mo before these polypides degenerated into brown bodies in the austral winter (June). Very few polypides were active in the period from June to August, when water-column food levels were at their lowest; after this period new polypides differentiated. Individual zooids typically underwent a total of five (I. rubefacta and N. flagellata), or at least four (H. antarcticum) complete polypide cycles before becoming senescent. Polypide lifetimes generally became shorter as the age of the zooid increased. Sexual reproduction was also distinctly seasonal in these species, with bands of ovicells or sexually reproductive zooids being formed each year in late summer once a given colony had grown to a threshold size (or age). Larvae were then brooded for ≃10 mo before being released in January/February (N. flagellata) or February/March (H. antarcticum). The seasonal patterns of polypide cycling are related clearly to the variations in food availability, and these species appear to have the longest zooid lifetime (≃5 yr) and the slowest polypide cycling (once per year with polypide lifetimes up to 10 mo) reported for any bryozoan so far.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050357
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  • 4
    Electronic Resource
    Electronic Resource
    Sublittoral epifaunal communities at Signy Island, Antarctica. I. The ice-foot zone (1995)
    Springer
    Marine biology 121 (1995), S. 555-563 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photographs were taken every 0.5 m along three transects of 5.5 m length on shallow rock faces at Signy Island, Antarctica, during the austral summer of 1991/1992. The percentage cover of substratum ranged from 0 to 100% and the colonising communities included representatives of ten phyla. The zone from mean low-water neap level to 1.5 m depth was mostly devoid of organisms as a result of the seasonal formation of the encrusting ice foot. Coralline and macroalgae dominated from 2 to 3 m, and animal groups from 3.5 to 5.5 m. Bryozoans, and to a lesser extent sponges, were the most abundant animal phyla. Within the bryozoans a succession of colonisation of different species was observed, the most abundant two of which occupied 〉80% of substratum in places. Substratum type seemed to be the main factor influencing community development in the shallow sublittoral at Signy Island, although ice impact prevents community development in the top 1.5 m and limits it over the rest of the transect down to 5.5 m. Depth and profile of substratum also influenced communities within this depth range (particularly taxonomic composition).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349466
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  • 5
    Electronic Resource
    Electronic Resource
    Sublittoral epifaunal communities at Signy Island, Antarctica. II. Below the ice-foot zone (1995)
    Springer
    Marine biology 121 (1995), S. 565-572 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photographic samples were taken every 5 m along two 40 m transects on mostly rock face at Signy Island, Antarctica, during the austral winter of 1991. Dense and taxonomically rich communities of benthos occurred at most of the sublittoral study locations. These communities, however, varied significantly with substratum type, substratum profile and depth. Algae were generally the largest occupiers of space, but the area of substratum colonised by animal taxa increased whenever the profile approached vertical. Shallower than 15 m, disturbance effects, largely from ice, restricted community development to a high degree, but the frequency of disturbance at 25 m appeared to maintain high diversity by preventing domination of the assemblage by a few competitively superior taxa. Bryozoans, and to a lesser extent sponges, were the most abundant animal phyla. Among the bryozoans, species with an encrusting growth form occurred at the shallowest depths followed by encrusting massive/folaceous species and, at 40 m, the erect flexible forms. The ratio of encrusting to erect bryozoan species changed rapidly over the 0 to 50 m depth zone, from exclusively encrusting at 0 to 5 m to approaching 1 at 50 m. The erect bryozoans studied, from the shallow sublittoral to 290 m, could be classified as encrusting massive (foliaceous), erect flexible or erect rigid forms. There was some suggestion, despite the overlap between groups and considerable intra-group variation, that encrusting massive forms were abundant in the shallowest water, followed by erect flexible forms and then erect rigid forms with increasing depth. Some species which occurred as encrusting massive/foliaceous forms in deeper water occurred mostly in encrusting form only in shallow water (〈15 m).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349467
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  • 6
    Electronic Resource
    Electronic Resource
    Amorphous Tumours induced in Alfalfa by Potato Leafhoppers (1963)
    [s.l.] : Nature Publishing Group
    Nature 199 (1963), S. 95-96 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Granovsky1'4 suggested that leaf hoppers produced injury by introducing some chemical or enzymatic toxin into the plant with their salivary secretions. Histological and chemical studies by Smith and Poos5 and Smith6 demonstrated that feeding leaf hoppers injected a protein aceous sheath material ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/199095a0
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  • 7
    Electronic Resource
    Electronic Resource
    Gain from Two Cycles of Divergent Selection for Root Morphology in Alfalfa (1999)
    Springer
    Crop science 39 (1999), S. 1026-1035 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Medicago sativa L.) has been identified for use in phytoremediation. Phytoremediation is defined as the use of green plants to remove or contain environmental contaminants. Alteration of root morphology would increase the degradative efficiency of alfalfa for phytoremediation. Root morphology traits in alfalfa are heritable, but are strongly influence by dormancy and geographic origin. Our objective was to create alfalfa source germplasms that differ in root morphology within the same genetic background. Four experimental alfalfa germplasms differing dormancy and genetic origin were evaluated after two cycles of divergent selection for root morphology traits. Two sources were selected for few vs. many lateral roots and the other two sources were selected for few vs. many fibrous roots followed by one subsequent cycle of selection for few vs. many lateral roots. These divergent populations were evaluated using two fertilizer rates (0 and 200 kg N ha-1) and were established twice at each of two locations. Plants from one experiment at each location were dug at the end of the establishment year and from the second experiment at the end of the first production year. All plants were evaluated for number of lateral roots, fibrous root mass, taproot diameter, plant count per plot, and plot root weight. Two cycles of divergent selection for root morphology traits in all four source germplasms produced alfalfa populations that differed in root morphology. Realized heritabilities from all germplasm sources ranged from 21 to 48% for fibrous root mass and from 11 to 43% for lateral root number. Response to selection varied among the four source germplasms and indicated that the choice of parent germplasm will be a factor for success in producing alfalfa populations that differ in root morphology within a single genetic source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular and whole-plant responses to selection for enzyme activity in alfalfa root nodules: evidence for molecular compensation of aspartate aminotransferase expression (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 355-361 
    Details
    ISSN: 1432-2242
    Keywords: Glutamate oxalate transaminase ; Isozymes ; Nitrogen fixation ; Medicago sativa L. ; Rhizobium meliloti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The enzyme aspartate aminotransferase (AAT) plays a key role in the assimilation of fixed-N in alfalfa (Medicago sativa L.) root nodules. AAT activity in alfalfa nodules is due to the activity of two dimeric isozymes, AAT-1 and AAT-2, that are products of two distinct genes. Three forms of AAT-2 (AAT-2a, -2b, and-2c) have been identified. It was hypothesized that two alleles occur at the AAT-2 locus, giving rise to the three AAT-2 enzymes. In a prior study bidirectional selection for root nodule AAT and asparagine synthetase (AS) activities on a nodule fresh weight basis in two diverse alfalfa germ plasms resulted in high nodule enzyme activity subpopulations with about 20% more nodule AAT activity than low enzyme activity subpopulations. The objectives of the study presented here were to determine the inheritance of nodule AAT-2 production and to evaluate the effect of bidirectional selection for AAT and AS on AAT-2 allelic frequencies, the relative contributions of AAT-1 and AAT-2 to total nodule activity, nodule enzyme concentration, and correlated traits. Two alleles at the AAT-2 locus were verified by evaluating segregation of isozyme phenotypes among F1 and S1 progeny of crosses or selfs. Characterization of subpopulations for responses associated with selection was conducted using immunoprecipitation of in vitro nodule AAT activity, quantification of AAT enzyme protein by ELISA, and AAT activity staining of native isozymes on PAGE. Results indicate that selection for total AAT activity specifically altered the expression of the nodule AAT-2 isozyme. AAT-2 activity was significantly greater in high compared to low activity subpopulations, and high AAT subpopulations from both germ plasms had about 18% more AAT-2 enzyme (on a nodule fresh weight basis). No significant or consistent changes in AAT-2 genotypic frequencies in subpopulations were caused by selection for AAT activity. Since changes in AAT activity were not associated with changes in AAT-2 genotype, selection must have affected a change(s) at another locus (or loci), which indirectly effects the expression of nodule AAT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229494
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  • 9
    Electronic Resource
    Electronic Resource
    A multiple-trait breeding program for improving the symbiosis for N2 fixation betweenMedicago sativa L. andRhizobium meliloti (1984)
    Springer
    Plant and soil 82 (1984), S. 303-314 
    Details
    ISSN: 1573-5036
    Keywords: Acetylene reduction ; Disease resistance ; Host-Rhizobium strain interaction ; Nitrate reductase ; Nodule enzymes ; Nodule mass ; 15N evaluation ; Plant vigor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The goal of breeding alfalfa for increased N2 fixation potential is addressed. A chronological progression of breeding, physiological, microbiological, and plant pathological research is described. Studies describing the interrelationships among plant morphological, plant physiological, andRhizobium effectiveness traits are summarized. It was concluded that N2 fixation in alfalfa is affected by coordinated responses among many physiological and biochemical traits. The simultaneous improvement of many factors in the symbiosis requires a comprehensive multiple-step breeding program. The current program includes selection in the glasshouse for seedling vigor,Rhizobium preference, shoot growth, nodule mass, root growth, nitrogenase (as measured by acetylene reduction), and nodule enzyme activity. The inclusion of additional selection traits is anticipated. Field evaluations of N2 fixation potential of alfalfa populations are made with15N isotope dilution techniques. Plant germplasm sources used in the breeding program include several heterogeneous populations which have good combining ability and pest resistance when they are intercrossed. Significant progress has been made in achieving the goal of breeding alfalfa for improved N2 fixation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184269
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  • 10
    Electronic Resource
    Electronic Resource
    Bubble formation in animals. II. Gas nuclei and their distribution in blood and tissuesThis work has been aided since July 1, 1942, by grants from the Committee on Aviation Medicine of the National Research Council carried out under contract recommended by the Commitee on Medical Reseach between the Office of Scientific Research and Development and Princeton University. Reference will not be made to progress reports or other literature of the Committee on Aviation Medicine. (1944)
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 24 (1944), S. 23-34 
    Details
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1030240103
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