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  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Luteochrome isolated from the tubers of a white-fleshed variety of sweet potato (Ipomoea batatas LAM.) has been shown by HPLC, 1H-NMR and CD spectra to consist of a mixture of (5R,6S,5′R,8′R)- and (5R,6S,5′R,8′S)- 5,6:5′,8′-diepoxy-5,6,5′,8′-tetrahydro-β,β-carotene (1 and 2, resp.). Therefore, its precursor is (5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene (4). This is the first identification of luteochrome as a naturally occurring carotenoid and, at the same time, gives the first clue to the as yet unknown chirality of the widespread β,β-carotene diepoxide. These facts demonstrate that the enzymic epoxidation of the β-end group occurs from the α-side, irrespective of the presence of OH groups on the ring.
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  • 2
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
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  • 3
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Germanium (Ge), in the form of germanic acid, at a Ge/Si molar ratio of 1.0 inhibits gemmule development and silica deposition in the marine demosponge Suberites domuncula. Lower Ge/Si ratios inhibit the growth in length of the silica spicules (tylostyles) producing short structures, but with relatively normal morphology and close to normal width; spherical protuberances occasionally occur on these spicules. A few of the short spicules possess completely round rather than pointed tips. Many of the latter develop when Ge is added (pulsed) to growing animals, thus inducing a change in spicule type. These results indicate that the growth in length of the axial filament is more sensitive to Ge inhibition than is silica deposition and that pointed spicule tips normally develop because the growth of the axial filament at the spicule tip is more rapid than silica deposition. Newly formed spicules initiate silica deposition at the spicule head but the absence of Ge-induced bulbs as in freshwater spicules (oxeas) leaves open the question of whether there is a silicification center(s) present in Suberites tylostyles. The morphogenesis of freshwater oxeas and of marine tyolstyles appears fundamentally different-bidirectional growth in the former and unidirectional growth in the latter. X-ray analysis demonstrate relatively uniform Ge incorporation into the silica spicules with considerable variation from spicule to spicule in the incorporated level. Increased silicic acid concentration induces the formation of siliceous spheres, suggesting that the axial filament becomes prematurely encased in silica.
    Additional Material: 28 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 186 (1985), S. 343-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In this astrophorid sponge, both intercellular fibrils and spongin microfibrils are elaborated with the former forming exceptionally dense arrangements throughout much of the matrix. Fibrils are very dense below the surface where they surround the small silica asters and throughout the cortex in the form of bundles that can form pseudo-plywood arangements. In the endosome, fibril bundles are isolated and fewer in number. The surfaces of the large silica spicules are uniquely encased by intercellular fibrils or compacted intercellular fibrils that form a type of “fibrillar spongin” or spongin microfibrils intermixed with fibrils. Well developed microfibrillar spongin, intermixed with some fibrils, encases larger spicules below the sponge surface within the tissue and extends above the tissue surrounding spicules that emerge from the sponge thus placing this fibrillar matrix in direct contact with the sea water. The results of other studies suggest that the fibrils and microfibrils of this species are collagenous. The elaboration of these special matrices indicates that the differentiation of spongocytes (which secrete microfibrils) is weak and that the activity of lophocytes (which secrete fibril bundles) is highly labile. The variability of the fibrillar arrangements in this species supports the view that astrophorid sponges are possibly important for understanding the phylogeny of the organic skeletal matrix of sponges.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 395-400 
    ISSN: 0935-6304
    Keywords: Gas chromatography (GC) ; Fused silica ; Column technology ; Surface modification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for fabricating fused silica capillary columns which have specific surface properties but still retain the excellent strength, flexibility, and resilience of pure fused silica. By using the Modified Chemical Vapor Deposition process (MCVD), typically used for the production of optical fiber lightguides, inorganic dopants such as Al, Nd, Ge, and P can be introduced into the preform-tube by MCVD. Doped columns have a wide range of specific surface properties, and columns with undoped fused silica prepared by MCVD are more chemically inert and less acidic than columns prepared by conventional methods. This paper describes the method for fabricating capillaries and the initial studies to characterize them.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 113-117 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extension of the understanding of properties of films of metals produced on glass surfaces by vacuum evaporation has permitted the fabrication of film-resistance thermometers that with simple instrumentation accurately measure surface or average surface temperatures without altering the geography of that surface. Formerly unknown and unstabled related properties of such films have been classified and may be anticipated or eliminated by recommended experimental procedures. Films of several of the most chemically inert and refractory metals 300 to 3,000 Å. thick have been shown to attain accuracies as high as 0.01°C. for practical periods of time. Their use, which is described, is developing satisfactorily, and the technique and equipment for their preparation are relatively simple.
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  • 7
    ISSN: 0884-3996
    Keywords: Luminometer ; evaluation ; rapid microbiology ; ATP assay ; firefly luciferase ; photometer ; radiometer ; comparison ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An assessment has been carried out of the relative performance of ten instruments for quantification of adenosine triphosphate (ATP) by the firefly luciferase assay. The instruments evaluated were Amersham Amerlite Analyser, Dynatech Tube Luminometer, Dynatech Multiplate Luminometer, Dynatech Camera Luminometer, Hamilton Lumicon, LKB 1250 Luminometer, LKB 1251 Luminometer, Lumac Biocounter M2010A, Turner 20 TD Luminometer and a prototype version of the CLEAR Speed Tech 2000. An 800-fold difference in sensitivity was found between the most sensitive (Lumac, Turner) and the least sensitive (Dynatech Tube) of the conventional instruments. The Dynatech Camera Luminometer which worked on a completely different principle to the other instruments was about 5000 times less sensitive than the best of the photomultiplier tube instruments. The relative sensitivity of the instruments was maintained regardless of whether solutions of ATP in water or trichloroacetic acid extracts of bacteria were analysed. An analysis of 960 ATP bioluminescence assays showed that data obtained from such measurements are normally distributed.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 131 (1987), S. 29-35 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The compensatory growth of the kidney which is induced by unilateral ne-phrectomy is a highly regulated process resulting principally in hypertrophy of the remaining kidney. The events which regulate this process are unknown. We have examined the levels of transcripts for the proto-oncogenes, myc, H-ras, K-ras, and fos, and the cellular genes, H4 histone, ornithine aminotrans-ferase, and gamma-glutamyl transpeptidase, following unilateral nephrec-tomy in the rat. The pattern of expression of c-myc, c-H-ras, and c-K-ras during compensatory growth of the kidney differs from the pattern of expression of these proto-oncogenes during liver regeneration, in which, unlike the kidney, hyperplasia rather than hypertrophy predominates. The lack of change in the abundance of these proto-oncogene transcripts following unilateral nephrec-tomy suggests a primary relationship between the expression of these proto-oncogenes and DNA synthesis and indicates there may be separate signals for cell growth, one to double cell size and one to replicate DNA. Increased mRNA transcripts for the enzymes ornithine aminotransferase and gamma-glutamyl transpeptidase were induced in the contralateral kidney after ne-phrectomy. The time course of expression for these two enzymes differs. The early expression of the gamma-glutamyl transpeptidase gene may indicate an involvement of this glutathione-metabolizing enzyme during renal compensatory growth, while the function of the delayed increase in ornithine amino-transferase transcripts in the remaining kidney is not apparent.
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  • 9
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The osteopetrotic, microphthalmic (mi/mi) mouse lacks functional osteoclasts and has also been reported to be deficient in mast cells and natural-killer (NK) cells. The later deficiencies could be secondary to the osteopetrotic marrow, or a direct result of the mi allele. Therefore, heterozygotes were examined for these cell types, since these mice do not exhibit osteopetrosis. Adult +/mi animals have approximately 50%, and mi/mi animals examined by histologic techniques or tissue histamine levels have 0-10%, of the peritoneal, dermal, and intestinal mast cells compared with that of +/+ animals. Leukocyte histamine, indicative of the number of basophils, demonstrates the same pattern. Histamine content per mast cell in +/+ and +/mi animals is identical. The number of large granular lymphocytes (LGL) in splenic leukocyte preparations from +/mi animals is 50% that of +/+ animals, and these cells are undetectable in preparations from mi/mi mice. NK activity against YAC-1 cells paralleled the number of LGL present. The resorptive response of neonatal calvaria to parathyroid hormone was delayed in the case of cultured +/mi bone compared with that of +/+ bone, but the final rate of calcium release was identical. These data indicate that (1) the presence of one mi allele can affect the development of four distinct cell types, and (2) osteopetrosis alone does not account for the lack of mast cells, basophils, and NK cells in mi/mi mice.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 15 (1986), S. 43-56 
    ISSN: 0148-7280
    Keywords: calcium ; ultrastructure ; motility ; respiration ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rapid cooling (cold shocking) of washed ejaculated ram sperm to 0°C irreversibly reduced motility, tail beat frequency, and respiration and increased the uptake of 45Ca2+. The plasma membranes were removed from the sperm head, and the acrosomes were detached from the nuclei. The plasma membranes of the middle piece were removed, and the mitochondria contained pale and expanded cristae, similar in appearance to ATP-deprived mitochondria in the “condensed” configuration. The presence of 2.0 mg/ml phosphatidylcholine (lecithin) in the medium prevented ultrastructural damage on cold shock, and the motility, tail beat frequency, respiratory rate, and calcium uptake were maintained at levels similar to washed sperm. As the “protective” effect of phosphatidylcholine against cold shock was maintained to a certain extent after rewashing and centrifuging the sperm prior to cold shock, the interaction of phosphatidylcholine with ram sperm membranes may be fairly “tight” and not easily disrupted.
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