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  • Ultrastructure  (10)
  • Nodulation  (5)
  • Lepidoptera  (4)
  • Springer  (19)
  • 2005-2009
  • 1980-1984  (19)
  • 1965-1969
  • 1981  (19)
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Keywords
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  • Springer  (19)
Years
  • 2005-2009
  • 1980-1984  (19)
  • 1965-1969
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 107 (1981), S. 85-107 
    ISSN: 1615-6102
    Keywords: Male cytoplasmic inheritance ; Plumbago ; Pollen grain ; Pollen tube ; Sperm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Male gametes ofPlumbago zeylanica were examined in pollen grains and tubes using light and electron microscopy of chemically and physically fixed tissues, and Nomarski interference microscopy of isolated, living sperm cells. Male gametes are elongate, spindleshaped cells containing a nucleus, mitochondria, ER, ribosomes, vesicles, dictyosomes, probable microfilaments, and a variable number of plastids. In mature pollen grains ofP. zeylanica, the two sperm cells are directly linked; they share a transverse cell wall with plasmodesmata and are enclosed together by the inner vegetative cell plasma membrane. One of these two sperms is also associated with the vegetative nucleus as a consistent feature of pollen grain organization. The basis of this association appears to be a long, narrow projection of the sperm cell (averaging 〈 1 μm wide and about 30 μm long) which wraps around the periphery of the vegetative nucleus and occupies embayments of that nucleus. This association is maintained throughout pollen tube growth but becomes less extensive near the completion of tube growth and is severed following tube discharge. The consistent occurrence of the sperm-vegetative nucleus association in pollen grains, tubes and isolated pollen cytoplasm suggests that the two structures may be directly connected, but attempts to visualize this type of connection were unsuccessful. Possibly, the entwining nature and extent of complementary interfaces between vegetative nucleus and sperm may have a role in stabilizing their association. Functionally, the two sperms and vegetative nucleus appear to travel as a linked unit within the pollen tube, possibly increasing the effectiveness of gamete delivery and helping to ensure nearly simultaneous transmission of sperms into the receptive megagametophyte.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 30 (1981), S. 123-127 
    ISSN: 1570-7458
    Keywords: Sex Pheromones ; Repellent ; Heliothis armigera ; Heliothis zea ; Lepidoptera ; Noctuidae ; cotton bollworm ; corn earworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'examen en olfactomètre a porté sur les réactions face à d'autres femelles de la même espèce, de femelles vierges ou ayant copulé d'Heliothis armigera Hübner et H. zea Boddie. Le lot comprenait 8 femelles, vierges ou ayant copulé en présence d'une femelle vierge ou ayant copulé. Les 4 combinaisons possibles de femelles vierges et de femelles ayant copulé ont été examinées avec 12 répétitions pour chaque espèce. Un extrait de l'extrémité de l'abdomen de femelles vierges d'une espèce a été présenté aux femelles de l'autre espèce pour examiner les possibilités de réactions interspécifiques aux phéromones. Pour chaque espèce, les réactions interspécifiques de répulsion entre femelles ont été hautement significatives par rapport aux témoins, à l'exception toutefois des réactions de femelle ayant copulé face à des femelles ayant elles aussi copulé. Les répulsions moyennes chez H. armigera et H. zea pour les 8 femelles de chaque expérience ont été: a) vierges en présence d'une vierge: 7,33 et 7,66; b) vierges en présence d'une femelles ayant copulé: 5,76 et 5,58; c) femelles ayant copulé en présence d'une vierge: 4,67 et 4,83. Les différences sont hautement significatives entre chaque paire de moyennes et entre chaque paire et le lot témoin; 3,17; 3,17; 3,42; 4,00 pour H. armigera; 3,17; 3,50; 2,83 et 3,75 pour H. zea. Les femelles vierges des deux espèces, H. armigera et H. zea ont présenté une réaction de répulsion en présence d'un extrait de l'abdomen de l'autre espèce; les répulsions moyennes étant respectivement 5,53 et 5,33 contre 3,83 et 3,58 pour le lot trémoin. On peut en conclure que ces répulsions doivent entraîner une tendance à la répartition uniforme.
    Notes: Abstract An olfactometer was used to determine the effect of pheromones released by females of the bollworms Heliothis armigera (Hübner) and H. zea (Boddie) on females of the same species. Four combinations of virgin and mated females were tested for repellency of one to the other. Evidence is presented that females of the two bollworms were repelled by females of the same species. In addition, extracts of virgin female abdomens of each species repelled virgin females of the other species.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 130 (1981), S. 204-212 
    ISSN: 1432-072X
    Keywords: Agmenellum quadruplicatum ; Nitrogen starvation ; Ultrastructure ; PATO poststain ; Cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nitrogen limitation on the ultrastructure of the unicellular cyanobacterium, Agmenellum quadruplicatum, were studied by thin sectioning transmission electron microscopy. Nitrogen became limiting for growth 14–15 h after transfer to nitrogen-limiting medium, but cultures retained full viability for at least 45 h. The c-phycocyanin: chlorophyll a ratio and cellular nitrogen content of the culture dropped rapidly after 14–15 h, as a progressive deterioration of major cell structures took place. Phycobilisomes were degraded first, followed by ribosomes and, then, thylakoid membranes. These structures were virtually depleted from the cells within 26 h. Intracellular polysaccharide accumulated in place of the normal cell structures throughout this period. Nitrogen limitation did not affect polyphosphate bodies, carboxysomes, lipid granules, the cell envelope, or the extra-cellular glycocalyx. All of the ultrastructural changes resulting from nitrogen limitation were reversed upon addition of nitrate to a starved culture. Most cell structures were restored within 3 h, and restoration was complete within 9 h.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 60 (1981), S. 139-142 
    ISSN: 1573-5036
    Keywords: Legumes ; Nitrogen fixation ; Nodulation ; Winged beans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Only legumes of the cowpea cross-inoculation group, including the winged bean (Psophocarpus tetragonolobus) were found to form nodules in a temperate zone soil with no previous history of legume cropping. Isolates from root nodules from uninoculated winged beans grown in the field only nodulated legumes in the cowpea cross-inoculation group.Rhizobium japonicum formed ineffective nodules with the winged bean.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 603-618 
    ISSN: 1432-0827
    Keywords: Preameloblasts ; Tooth germs ; Monkey ; Enamel ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Cytodifferentiation of inner enamel epithelium and the adjacent connective tissue from the tip of the cervical loop to the initiation of enamel elaboration in twoMacaca species was examined. Ten- to twelve-month-old specimens were fixed by perfusion and the permanent tooth buds were prepared for transmission electron microscopy. At the cervical loop proper, inner enamel epithelium cells have lobed nuclei, a paucity of cytoplasm, and wide extracellular spaces; the basal lamina facing the dental papilla is straight. With increasing distance from the tip of the cervical loop, the following changes occur gradually: (a) preameloblasts elongate from 15 to 45 µm, and their organelles, particularly mitochondria and profiles of rough endoplasmic reticulum, become more numerous; (b) extracellular spaces decrease between preameloblasts starting at the basal (infranuclear) end; (c) the basement membrane becomes convoluted and associated with aperiodic fibers; (d) preodontoblast projections penetrate the aperiodic fibers; (e) collagen fibers subjacent to the basement membrane increase in density, with particularly thick fibers paralleling the aperiodic fibers. These modifications occur within three-fourths of the distance from the tip of the cervical loop to the mineralization front. The condensation of preodontoblasts is followed immediately by predentin synthesis. Concomitantly, the basement membrane breaks down and the aperiodic fibers are engulfed by preameloblasts. Preameloblast projections penetrate junctional predentin, contact mineralized dentin, and enamel synthesis ensues. At this stage the ameloblast is 45 µm long, the nucleus is central or basal, the Golgi apparatus has migrated apically, but the Tomes' process has not yet formed. The results indicate that odontogenesis inMacaca monkeys more closely resembles human odontogenesis than does that in the murine rodents.
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  • 6
    ISSN: 1615-6102
    Keywords: Dasya ; Mitosis ; Rhodophyta ; Spermatangia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitosis in the marine red algaDasya baillouviana (Ceramiales, Florideophyceae) was observed with the electron microscope. Most details of the process are quite similar to those observed in the other macroscopic red algae studied to date. However, some minor variations were noted. At late prophase a very small nuclear envelope protrusion (NEP) is formed at each division pole subjacent to the “nucleus associated organelle” known as the polar ring (PR) and 2–3 cisternae of perinuclear endoplasmic reticulum (PER) are commonly present during metaphase-anaphase. In contrast, in the other florideophycean algae where mitosis has been reported, a prominent NEP is present at late prophase (McDonald personal communication,Scott et al. 1980) and only a single cisterna of PER is observed. Additionally, during mid-late interphase and in mitotically-quiescent cells ofDasya, a single cisterna of smooth-surfaced ER is always juxtaposed with each PR. The possible significance of PER in theFlorideophyceae and other multinucleate organisms is discussed as well as the likely functions of spindle-associated smooth ER. It is suggested that ultrastructural features of mitosis should be useful as criteria to aid in the interpretation of the phylogeny of red algae.
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  • 7
    ISSN: 1573-5036
    Keywords: Acetylen reduction assay ; Aluminium toxicity ; Chemical composition ; Cowpea ; Cultivar tolerance to soil acidity ; Liming ; Nitrogen deficiency ; Nitrogenase activity ; Nodulation ; Relative dry matter yields ; Soil acidity ; Ultisol ; Lime-induced yield depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The differential response of six cowpea (Vigna unguiculata (L.) Walp) cultivars to liming was assessed in a greenhouse trial using an Ultisol (Typic Paleudult) from southeastern Nigeria. Lime rates from 0 to 5.0 t/ha were applied to give a range of soil pH, determined in 1∶1 soil/water from 4.25 to about 7.0. Without liming, relative dry matter yields of tops ranged between 46.6 and 76.8 percent. Significant yield responses to the first lime increment (0.5 t/ha) were observed particularly in the less tolerant cultivars and maximum yields were generally obtained with application of 1.6 to 2.5 t/ha lime. Among the six cultivars, TVu 4557 and Ife Brown were most tolerant, Vita-1 and Vita-3 were moderately tolerant, and TVu 1977-OD and TVu 4552 were least tolerant to soil acidity. The latter two cultivars were the most poorly nodulated when grown in the unlimed soil. The first lime increment enabled excellent nodulation to be achieved in all cultivars. Nitrogen analyses on tops confirmed the visual symptoms of nitrogen deficiency in two cultivars (Vita-1, TVu 1977-OD) grown in the unlimed soil. Analysis of data on chemical composition of plant tops and chemical soil characteristics gave indications that aluminium toxicity is the major growth limiting factor for cowpeas in this soil. This study, albeit with a limited range of cowpea germplasm clearly indicates that cowpea possesses considerable potential as a grain legume on strongly acid soils (pH〈5.0), even in circumstances where lime is not available. Low rates of lime (0.5 t/ha or less) will greatly expand the available choice of cultivars.
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  • 8
    ISSN: 1573-5036
    Keywords: Cations ; Interaction ; Mycorrhiza ; Nodulation ; Phosphate ; Trifolium subterraneum ; VAM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Conclusions Mycorrhizal fungi increase the rate of phosphate uptake by roots (P inflow) over a range of soil P levels even when mycorrhizal growth increases no longer occur. It is likely that the fungi play a direct part in uptake and translocation of P to the roots. V.A.M. effects on nodulation and N2 fixation are largely indirect, probably resulting from improved P nutrition and growth at low soil P levels. Work on inorganic cation nutrition is much less advanced, but it is already clear that there are interactions between P nutrition and cation uptake which may also be indirect. The pattern of N assimilation (N2 fixation vis-à-vis NaNO3 or (NH4)2SO4 uptake) may modify cation/P interactions. Further work is required to distinguish cause and effect and to clarify the role played by V.A.M. fungi.
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  • 9
    ISSN: 1573-1561
    Keywords: Synthesis ; isomers ; 5,7-dodecadienal ; sex pheromone ; Malacosoma disstria ; Malacosoma californicum ; Lepidoptera ; Lasiocampidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract All four geometrical isomers of 5,7-dodecadien-1-ol have been stereoselectively synthesized by using Wittig condensation reactions. (5 Z,7E)-5,7-Dodecadien-1-ol and its corresponding aldehyde are components of the sex pheromone of the forest tent caterpillar. (5 E,7 Z)-5,7-Dodecadienal is a component of the pheromone of the western tent caterpillar. These compounds have been successfully tested in the field.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 7 (1981), S. 615-625 
    ISSN: 1573-1561
    Keywords: Redbacked cutworm ; Euxoa ochrogaster ; Lepidoptera ; Noctuidae ; sex pheromone blend ; sex attractant ; parapheromone ; Z-5-decenyl acetate ; Z-5-undecenyl acetate ; Z-5-dodecenyl acetate ; Z-7-dodecenyl acetate ; Z-9-dodecenyl acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Four acetates,Z-5-decenyl acetate,Z-5-,Z-7-, andZ-9-dodecenyl acetates, in microgram ratios of 1∶200∶2∶1 or 1∶200∶6∶2 were excellent, specific sex pheromone blends for capturing male redbacked cutworm moths in cone traps. Blends in ratios of 1∶200∶2∶1 and 2∶200∶2∶1 at 1000 μg/ rubber septum dispenser remained highly effective for 6 weeks under field conditions. The essential minor components,Z-5-decenyl,Z-7-, andZ-9-dodecenyl acetates, became inhibitory at concentrations of about 10% in the blends, and this may be an important general phenomenon in lepidopteran pheromones. Blends involving a parapheromone,Z-5-undecenyl acetate, withZ-5-,Z-7-, andZ-9-dodecenyl acetate, in microgram ratios of 8∶200∶2∶1 or 20∶200∶6∶2 were also excellent specific attractants for this species. TheZ-8-dodecenyl acetate had no obvious effect on the attraction of the redbacked cutworm males.
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