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  • Ultrastructure  (43)
  • Adult  (42)
  • Springer  (43)
  • American Association for the Advancement of Science (AAAS)  (42)
  • American Chemical Society
  • American Geophysical Union
  • 1980-1984  (85)
Collection
Publisher
  • Springer  (43)
  • American Association for the Advancement of Science (AAAS)  (42)
  • American Chemical Society
  • American Geophysical Union
Years
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
    Publication Date: 1981-12-04
    Description: Leucine catabolism is regulated by either of the first two degradative steps: (reversible) transamination to the keto acid or subsequent decarboxylation. A method is described to measure rates of leucine transamination, reamination, and keto acid oxidation. The method is applied directly to humans by infusing the nonradioactive tracer, L-[15N,1-13C]leucine. Leucine transamination was found to be operating several times faster than the keto acid decarboxylation and to be of equal magnitude in adult human males under two different dietary conditions, postabsorptive and fed. These results indicate that decarboxylation, not transamination, is the rate-limiting step in normal human leucine metabolism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Matthews, D E -- Bier, D M -- Rennie, M J -- Edwards, R H -- Halliday, D -- Millward, D J -- Clugston, G A -- AM-25994/AM/NIADDK NIH HHS/ -- HD-10667/HD/NICHD NIH HHS/ -- RR-00954/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1981 Dec 4;214(4525):1129-31.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7302583" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Carbon Isotopes ; Humans ; Kinetics ; Leucine/*metabolism ; Male ; Models, Biological ; Nitrogen Isotopes ; Oxidation-Reduction
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 1984-07-06
    Description: A retrovirus isolated from three patients with the acquired immunodeficiency syndrome (AIDS) in the United States was morphologically and antigenically identical to lymphadenopathy associated virus isolated in France. Two of these isolates were from a blood donor-recipient pair, each of whom developed AIDS. Lymphadenopathy associated virus was isolated from the blood donor's lymphocytes 12 months after his onset of AIDS symptoms and from the blood recipient's lymphocytes 1 month after her onset of AIDS symptoms. Two isolates from the blood donor-recipient pair and an isolate from an epidemiologically unrelated homosexual man were examined by competitive radioimmunoassay to determine their antigenic relatedness to each other and to other human retroviruses. The major core proteins (p25) of the isolates were antigenically identical and all three isolates were identical to prototype lymphadenopathy associated virus isolated in France.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Feorino, P M -- Kalyanaraman, V S -- Haverkos, H W -- Cabradilla, C D -- Warfield, D T -- Jaffe, H W -- Harrison, A K -- Gottlieb, M S -- Goldfinger, D -- Chermann, J C -- New York, N.Y. -- Science. 1984 Jul 6;225(4657):69-72.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6328663" target="_blank"〉PubMed〈/a〉
    Keywords: Acquired Immunodeficiency Syndrome/*microbiology/transmission ; Adult ; Antibodies, Viral/immunology ; *Blood Donors ; Blood Transfusion/adverse effects ; Deltaretrovirus/immunology ; Female ; Humans ; Male ; Retroviridae/*immunology ; Retroviridae Infections/*immunology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 1984-08-31
    Description: Plasma-free homovanillic acid, a major metabolite of dopamine, was measured in chronically ill schizophrenic patients both before and during treatment with the antipsychotic phenothiazine, fluphenazine. Neuroleptic treatment was associated with a significant time-dependent decrease in plasma homovanillic acid from pretreatment values, which were significantly elevated when compared with those of age- and sex-matched healthy control subjects. Further, both the absolute concentrations as well as the neuroleptic-induced reductions in plasma homovanillic acid determined over 5 weeks of neuroleptic treatment were statistically significantly correlated with ratings of psychosis and improvement in psychosis, respectively. These findings suggest that the delayed effects of neuroleptic agents on presynaptic dopamine activity may more closely parallel their therapeutic actions than do their immediate effects in blocking postsynaptic dopamine receptors and that a decrease in dopamine "turnover" may be responsible for their antipsychotic effects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pickar, D -- Labarca, R -- Linnoila, M -- Roy, A -- Hommer, D -- Everett, D -- Paul, S M -- New York, N.Y. -- Science. 1984 Aug 31;225(4665):954-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6474162" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Dopamine/metabolism ; Female ; Fluphenazine/pharmacology/*therapeutic use ; Homovanillic Acid/*blood ; Humans ; Male ; Phenylacetates/*blood ; Schizophrenia/blood/*drug therapy ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 1982-08-13
    Description: Cognitive activity resulted in increased flow of blood to the cerebral hemispheres. The increase was greater to the left hemisphere for a verbal task and greater to the right hemisphere for a spatial task. The direction and degree of hemispheric flow asymmetry were influenced by sex and handedness, females having a higher rate of blood flow per unit weight of brain, and females and left-handers having a greater percentage of fast-clearing tissue, presumably gray matter.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gur, R C -- Gur, R E -- Obrist, W D -- Hungerbuhler, J P -- Younkin, D -- Rosen, A D -- Skolnick, B E -- Reivich, M -- MH 30456/MH/NIMH NIH HHS/ -- NS-10939-09/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1982 Aug 13;217(4560):659-61.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7089587" target="_blank"〉PubMed〈/a〉
    Keywords: Adolescent ; Adult ; Brain/metabolism/*physiology ; *Cerebrovascular Circulation ; *Cognition ; Female ; *Functional Laterality ; Humans ; Male ; Metabolic Clearance Rate ; Rest ; *Sex Characteristics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 133 (1982), S. 11-19 
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Mastigocladus laminosus ; Fischerella ; True branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology and ultrastructure of the thermophilic cyanobacteriumMastigocladus laminosus were examined by scanning and transmission electron microscopy. Mature cultures consisted of relatively old, wide filaments that branched frequently to form younger, thinner filaments. The cells of the younger filaments had a consistently cylindrical morphology, while those of older filaments were rounded and pleomorphic. The internal ultrastructure of the cells depended somewhat on their age. As young cells became larger and wider, their thylakoids underwent slight rearrangement and spread out toward the center of the cytoplasm. Polyphosphate bodies, carboxysomes (polyhedral bodies), and lipid-body-like structures increased in number as the cells aged, but ribosomes and cyanophycin granules were depleted. Cell division involved septum formation followed by ingrowth of the outer membrane and sheath. Cells in older filaments were separated from each other by a complete layer of sheath material. Septum formation in older cells was also seen to occur parallel to the long axis of the filament, thereby confirming that true branching took place.
    Type of Medium: Electronic Resource
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  • 7
    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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  • 8
    ISSN: 1432-0878
    Keywords: Ecdysteroids ; Moulting hormones ; Xyleborus ferrugineus pupae ; Ultrastructure ; Prothoracic gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The prothoracic glands of female pupae of Xyleborus ferrugineus at three ages (0-h, 48-h and 72-h-old) were examined for ultrastructural changes that correlate with high titers of ecdysteroids in the entire pupa. In all three ages, the prothoracic gland cells appear compact with a prominent nucleus. Lysosome-like structures with concentrically oriented internal membrane are observed in both 0-h and 72-h-old gland cells. Mitochondria are abundant in the glands of both ages, and rough endoplasmic reticulum is relatively sparse. Numerous microtubules are present in the prothoracic gland cells of 48-h-old female pupae that contain relatively high titers of ecdysteroids. Rough endoplasmic reticulum also is especially abundant at this age of the pupa. Ecdysone titers, estimated by the radioimmunoassay method (RIA), were 161.04±22.61 pg/mg, 704.25±69.02 pg/mg and 298.72±26.80pg/mg body weight in 0-h, 48-h and 72-h-old female pupae, respectively.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 116 (1983), S. 1-13 
    ISSN: 1615-6102
    Keywords: Cuticle ; Peristomatal transpiration ; Stomata ; Ultrastructure ; Funaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cuticle and pore development in the guard cells ofFunaria were investigated with the electron microscope. Pore cuticle formation is simultaneous with the creation of the pore itself. The morphology of the pore cuticle is unlike that of any cuticle described in the literature. It has many lamellae which are penetrated by electron dense fibrils. Three different cuticular morphologies exist from the pore to the subsidiary cell walls. The cuticles on the pore and outer walls contain fibrils that sometimes reach to the surface. The subsidiary cell cuticle lacks fibrils altogether. It is hypothesized that (1) cuticularization of the middle lamella contributes to ventral wall separation and (2) differences in extent of cuticular fibrils are related to greater water loss from stomata than from subsidiary cells (peristomatal transpiration).
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 228 (1983), S. 389-403 
    ISSN: 1432-0878
    Keywords: Lymph node, avian ; Ultrastructure ; Macrophages ; Phagocytic capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of the avian lymph node (ALN) is characterized by a thin capsule, thin lymphoreticular cords, and an absence of trabeculae. It is not possible to subdivide the ALN into cortex, paracortex and medulla, or to subdivide the system of sinuses into marginal, trabecular and medullary divisions. The lymphoreticular cords contain avian germinal centers (AGC) with B-lymphocytes and the area of T-lymphocytes. Postcapillary venules are responsible for the recirculation of lymphocytes. Sinus reticular cells do not exist in the ALN, but free macrophages are present. The phagocytic capacity of the macrophages was determined by injection of vital dyes (India ink, Berlin blue) and inoculation with Candida cells. Macrophages filled with markers migrate from the lymph sinuses into the lymphoreticular cords and further into the AGC. The mobility of the macrophages is remarkably lower after phagocytosis of Candida cells.
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