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  • 1
    Electronic Resource
    Electronic Resource
    Poly(dimethylsiloxane) as a reference standard for exact mass measurement in chemical ionization mass spectrometry (1987)
    s.l. : American Chemical Society
    Analytical chemistry 59 (1987), S. 194-197 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00128a040
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  • 2
    Electronic Resource
    Electronic Resource
    ENDOR and Special TRIPLE Resonance Spectroscopy of QA.bul.- of Photosystem 2 (1995)
    s.l. : American Chemical Society
    Biochemistry 34 (1995), S. 12075-12081 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00037a051
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and Antitumor Activity of Novel Water Soluble Derivatives of Camptothecin as Specific Inhibitors of Topoisomerase I (1995)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 38 (1995), S. 395-401 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00003a001
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  • 4
    Electronic Resource
    Electronic Resource
    Calcium ion dependency of ethylene production in segments of primary roots of Zea mays (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 67 (1986), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We investigated the effect of Ca2+ on ethylene production in 2-cm long apical segments from primary roots of corn (Zea mays L., B73 × Missouri 17) seedlings. The seedlings were raised under different conditions of Ca2+ availability. Low-Ca and high-Ca seedlings were raised by soaking the grains and watering the seedlings with distilled water or 10 mM CaCl2, respectively. Segments from high-Ca roots produced more than twice as much ethylene as segments from low-Ca roots. Indoleacetic acid (IAA; 1 μM) enhanced ethylene production in segments from both low-Ca and high-Ca roots but auxin-induced promotion of ethylene production was consistently higher in segments from high-Ca roots. Addition of I-aminocyclopropane-I-carboxylic acid (ACC) to root segments from low-Ca seedlings doubled total ethylene production and the rate of production remained fairly constant during a 24 h period of monitoring. In segments from high-Ca seedlings ACC also increased total ethylene production but most of the ethylene was produced within the first 6 h. The data suggest that Ca2+ enhances the conversion of ACC to ethylene. The terminal 2 mm of the root tip were found to be especially important to ethylene biosynthesis by apical segments and, experiments using 45Ca2+ as tracer indicated that the apical 2 mm of the root is the region of strongest Ca2+ accumulation. Other cations such as Mn2+, Mg2+, and K+ could largely substitute for Ca2+. The significance of these findings is discussed with respect to recent evidence for gravity-induced Ca2+ redistribution and its relationship to the establishment of asymmetric growth during gravitropic curvature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1986.tb05057.x
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  • 5
    Electronic Resource
    Electronic Resource
    The influence of calcium and pH on growth in primary roots of Zea mays (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 72 (1988), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hasenstein, K. H. and Evans, M. L. 1988. The influence of calcium and pH on growth in primary roots of Zea mays. - Physiol. Plant. 72: 466–470.We investigated the interaction of Ca2+ and pH on root elongation in Zea mays L. cv. B73 × Missouri 17 and cv. Merit. Seedlings were raised to contain high levels of Ca2+ (HC, imbibed and raised in 10 mM CaCl2) or low levels of Ca2+ (LC, imbibed and raised in distilled water). In HC roots, lowering the pH (5 mM MES/Tris) from 6.5 to 4.5 resulted in strong, long-lasting growth promotion. Surprisingly, increasing the pH from 6.5 to 8.5 also resulted in strong growth promotion. In LC roots acidification of the medium (pH 6.5 to 4.5) resulted in transient growth stimulation followed by a gradual decline in the growth rate toward zero. Exposure of LC roots to high pH (pH shift from 6.5 to 8.5) also promoted growth. Addition of EGTA resulted in strong growth promotion in both LC and HC roots. The ability of EGTA to stimulate growth appeared not to be related to H+ release from EGTA upon Ca2+ chelation since, 1) LC roots showed a strong and prolonged response to EGTA, but only a transient response to acid pH, and 2) promotion of growth by EGTA was observed in strongly buffered solutions. We also examined the pH dependence of the release of 45Ca2+ from roots of 3-day-old seedlings grown from grains imbibed in 45Ca2+. Release of 45Ca2+ from the root into agar blocks placed on the root surface was greater the more acidic the pH of the blocks. The results indicate that Ca2+ may be necessary for the acid growth response in roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1988.tb09152.x
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  • 6
    Electronic Resource
    Electronic Resource
    Cellular specificity of the gravitropic motor response in roots (1997)
    Springer
    Planta 203 (1997), S. S115 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Arabidopsis ; Auxin ; Calcium ; Distal elongation zone ; Gravitropism (root) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. A number of features of the gravitropic response of roots are not readily accounted for by the classical Cholodny-Went theory. These include the observations that (i) in the later stages of the response the growth gradient is reversed with no evident reversal of the auxin gradient; (ii) a major component of the acceleration of growth along the upper side occurs in the distal elongation zone (DEZ), a group of cells located between the meristem and the main elongation, not within the central elongation zone; and (iii) the initiation of differential growth in the DEZ appears to be independent of the establishment of auxin asymmetry. Alternative candidates for mediation of differential growth in the DEZ include calcium ions and protons. Gravi-induced curvature is accompanied by polar movement of calcium toward the lower side of the maize root tip and the DEZ is shown to be particularly sensitive to growth inhibition by calcium. Also, gravistimulation of maize roots causes enhanced acid efflux from the upper side of the DEZ. Evidence for gravi-induced modification of ion movements in the root tip includes changes in intracellular potentials and current flow. It is clear that there is more than one motor region in the root with regard to gravitropic responses and there is evidence that the DEZ itself consists of more than one class of responding cells. In order to gain a more complete understanding of the mechanism of gravitropic curvature, the physiological properties of the sub-zones of the root apex need to be thoroughly characterized with regard to their sensitivity to hormones, calcium, acid pH and electrical perturbations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008099
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of changes in relative elemental growth rate patterns in the elongation zone of Arabidopsis roots upon gravistimulation (1998)
    Springer
    Planta 206 (1998), S. 598-603 
    Details
    ISSN: 1432-2048
    Keywords: Key words:Arabidopsis (gravitropism ; root growth)  ;  Distal elongation zone  ;  Gravitropism  ;  Growth profiles  ;  Relative elemental growth rate  ;  Root growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Although Arabidopsis is an important system for studying root physiology, the localized growth patterns of its roots have not been well defined, particularly during tropic responses. In order to characterize growth rate profiles along the apex of primary roots of Arabidopsis thaliana (L.) Heynh (ecotype Columbia) we applied small charcoal particles to the root surface and analyzed their displacement during growth using an automated video digitizer system with custom software for tracking the markers. When growing vertically, the maximum elongation rate occurred 481 ± 50 μm back from the extreme tip of the root (tip of root cap), and the elongation zone extended back to 912 ± 137 μm. The distal elongation zone (DEZ) has previously been described as the apical region of the elongation zone in which the relative elemental growth rate (REGR) is ≤30% of the peak rate in the central elongation zone. By this definition, our data indicate that the basal limit of the DEZ was located 248 ± 30 μm from the root tip. However, after gravistimulation, the growth patterns of the root changed. Within the first hour of graviresponse, the basal limit of the DEZ and the position of peak REGR shifted apically on the upper flank of the root. This was due to a combination of increased growth in the DEZ and growth inhibition in the central elongation zone. On the lower flank, the basal limit of the DEZ shifted basipetally as the REGR decreased. These factors set up the gradient of growth rate across the root, which drives curvature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050437
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  • 8
    Electronic Resource
    Electronic Resource
    Nonselective ionic channels inAplysia neurones (1986)
    Springer
    The journal of membrane biology 93 (1986), S. 75-83 
    Details
    ISSN: 1432-1424
    Keywords: single channel ; chloride ; selectivity ; conductance state ; Aplysia neurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Single-channel recordings from outside-out patches ofAplysia neurones in K-free solutions revealed the presence in most membrane patches of ionic channels showing surprising selectivity properties, as deduced from reversal potential measurements. After complete substitution of external NaCl by mannitol (in the presence of internal CsCl), these channels are more permeable to Cl than to Cs, but are also slightly permeable to Cs:P Cl/P Cs=4. Furthermore, in the presence of external NaCl, their ability to discriminate cations from anions seems lower than in external mannitol. Substitutions of external Cl by various anions showed that the channels are more permeable to NO3 than to Cl, and that they are appreciably permeable to isethionate, SO4 and methanesulfonate. Their elementary conductance is about 100 pS in 600mm symmetrical Cl. However, different conductance states (usually 2 or 3) can often be detected in the same membrane patch. By using voltage ramps, we established theI–V curves corresponding to each of these states and found small but significant differences between the reversal potentials of each state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871020
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  • 9
    Electronic Resource
    Electronic Resource
    Analysis of growth patterns during gravitropic curvature in roots ofZea mays by use of a computer-based video digitizer (1986)
    Springer
    Journal of plant growth regulation 5 (1986), S. 73-83 
    Details
    ISSN: 1435-8107
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A computer-based video digitizer system is described which allows automated tracking of markers placed on a plant surface. The system uses customized software to calculate relative growth rates at selected positions along the plant surface and to determine rates of gravitropic curvature based on the changing pattern of distribution of the surface markers. The system was used to study the time course of gravitropic curvature and changes in relative growth rate along the upper and lower surface of horizontally-oriented roots of maize (Zea mays L.). The growing region of the root was found to extend from about 1 mm behind the tip to approximately 6 mm behind the tip. In vertically-oriented roots the relative growth rate was maximal at about 2.5 mm behind the tip and declined smoothly on either side of the maximum. Curvature was initiated approximately 30 min after horizontal orientation with maximal (50°) curvature being attained in 3 h. Analysis of surface extension patterns during the response indicated that curvature results from a reduction in growth rate along both the upper and lower surfaces with stronger reduction along the lower surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025958
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  • 10
    Electronic Resource
    Electronic Resource
    Plasma fluorescein and fluorescein glucuronide in patients with selected eye diseases (1989)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 227 (1989), S. 114-117 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Systemically administered fluorescein (F) is rapidly transformed to the fluorescent metabolite fluorescein glucuronide (FG). Little is known about how diseases can influence the synthesis or disposition of FG. We studied F and FG in the plasma ultrafiltrate of 75 people who were normal or had diabetes, retinitis pigmentosa, or idiopathic rhegmatogenous retinal detachment. F and FG were determined by high-performance liquid chromatography. The concentration of FG was comparable to F 1 h after an intravenous injection of F, both in normal subjects and in patients with retinitis pigmentosa, which suggests that FG may not be an important contributor to the vitreous fluorescence at that time. At later times FG substantially exceeded F. The concentration of FG was significantly higher in diabetics than in the other groups 14 h after an oral dose of F. Accordingly, the possible effect of disease on plasma dye concentrations should be considered in studies measuring F by fluorescence hours after systemic F administration, since this could influence the intraocular fluorescence irrespective of any alteration in ocular function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02169781
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