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  • 1995-1999  (11)
  • 1840-1849  (2)
  • Analytical Chemistry and Spectroscopy  (5)
  • Organic Chemistry  (3)
  • Phospholipids  (3)
  • Herbivory  (2)
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Material
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Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Herbivory and tree mortality across a pinyon pine hybrid zone (1995)
    Springer
    Oecologia 101 (1995), S. 29-36 
    Details
    ISSN: 1432-1939
    Keywords: Dioryctria albovittella ; Herbivory ; Hybrid Matsucoccus acalyptus ; Pinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the abundances of three common insect herbivores on pure and hybrid pinyon pines along a 250-km transect in west-central Arizona, United States. Using six morphological traits, we developed a hybrid index to classify trees as pure Pinus californiarum, hybrid, or pure Pinus edulis. The insects (the stem-boring moth, Dioryctria albovittella, the scale insect, Matsucoccus acalyptus, and several species of pitch moths that produce wounds on the trunk and branches) exhibited different distributional patterns across tree types. Stem-boring moths were significantly more abundant on trees at “hybrid” sites compared to trees at “pure” sites. In addition, within hybrid sites, hybrids supported significantly more moth larvae than pure trees of either species. These two patterns support the hybrid susceptibility hypothesis in which hybrid breakdown results in increased susceptibility to herbivory. In contrast to stem-borers, there were significantly more pitch moth wounds on trees at pure P. californiarum sites than at hybrid and pure P. edulis sites. Within the hybrid zone, pitch moth abundance was equal on pure P. californiarum and hybrids, and both were significantly greater than on pure P. edulis. These within-site comparisons support the dominance hypothesis where hybrid resistance differs from one tree species, but not the other. Scale insects exhibited the most restricted distribution; over the 250 km transect they were found only in the hybrid zone. This supports the hybrid susceptibility and/or the stress hypothesis (i.e., species at the edge of their range suffer greater stress and are more susceptible to herbivory). We summed the mean numbers of these three common herbivores across sites and found that hybrid sites supported 2.1 and 3.9 times more herbivores than pure P. californiarum and P. edulis sites, respectively. Furthermore, tree mortality was on average, 35 times greater within the hybrid zone compared to pure zones of each species and was associated with the cumulative abundance of herbivores (r 2=0.646). Regardless of whether this mortality is due to insect infestation, stress or a combination of both, these results suggest that hybrid zones are important arenas of natural selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328896
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  • 2
    Electronic Resource
    Electronic Resource
    Increased moth herbivory associated with environmental stress of pinyon pine at local and regional levels (1997)
    Springer
    Oecologia 109 (1997), S. 389-397 
    Details
    ISSN: 1432-1939
    Keywords: Key words Dioryctria albovittella ; Herbivory ; Pinus edulis ; Stress ; Vigor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Using 6 years of observational and experimental data, we examined the hypothesis that water and nutrient stress increase the susceptibility of pinyon pine (Pinus edulis) to the stem- and cone-boring moth (Dioryctria albovittella). At two geographic levels, a local scale of 550 km2 and a regional scale of 10,000 km2, moth herbivory was strongly correlated with an edaphic stress gradient. At a local scale, from the cinder soils of Sunset Crater to nearby sandy-loam soils, nine of ten soil macro- and micronutrients, and soil water content were lowest in cinder-dominated soils. Herbivore damage was six times greater on trees growing in the most water and nutrient deficient site at Sunset Crater compared to sites with well-developed soils. Percentage silt-clay content of soil, which was highly positively correlated with soil nutrient and soil moisture at a local scale, accounted for 56% of the variation in herbivory at a regional scale among 22 sites. Within and across sites, increased stem resin flow was positively associated with reduced moth attack. On the basis of moth distribution across a stress gradient, we predicted that pinyons growing in highly stressful environments would show increased resistance to herbivores if supplemented with water and/or nutrients. We conducted a 6-year experiment at a high-stress site where individual trees received water only, fertilizer only, and water + fertilizer. Relative to control trees, stem growth and resin flow increased in all three treatments, but only significantly in the water + fertilizer treatment. Although there was no significant difference in herbivore damage among these three treatments, there was an overall reduction in herbivore damage on all treatment trees combined, compared to control trees. This experiment suggests that release from stress leads to increased resistance to insect attack and is consistent with our observational data. While other studies have predicted that short-term stress will result in herbivore outbreaks, our studies extend this prediction to chronically stressed host populations. Finally, while flush-feeders are not predicted to respond positively to stressed host plants, we found a positive association between herbivore attack and stressed pinyon populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050098
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  • 3
    Electronic Resource
    Electronic Resource
    Glycosyl Imidates, 78Part 77: Ref.[1].. An Efficient Synthesis of Galactinol and Isogalacatinol (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 859-863 
    Details
    ISSN: 0947-3440
    Keywords: myo-Inositol, racemate resolution ; Glycosylation, trichloroacetimidate method ; Tin(II) trifluoromethanesulfonate catalyst ; Oligosaccharide ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2:3,4:5-Di-O-cyclohexylidene-D-/L-myo-inositol (2) could be readily converted into 6-O- and 1-O-unprotected L- and D-myo-inositol derivatives L- and D-4 and L- and D-6, respectively. Their reaction with trichloroacetimidate 7 as galactosyl donor in the presence of tin(II) trifluoromethanesulfonate as catalyst afforded the desired α(1-6)- and α(1-1)-connected galactopyranosides 8, 11 and 12. Compound 11 could be readily deprotected to afford target molecule (galactinol) 1 in high overall yield; from 12, the diastereoisomer 13 was obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970511
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  • 4
    Electronic Resource
    Electronic Resource
    Glycosyl Phosphatidylinositol (GPI) Anchor Synthesis Based on Versatile Building Blocks - Total Synthesis of a GPI Anchor of Yeast (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1153-1165 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Phospholipids ; Glycolipids ; Sphingosines ; Ceramides ; Ceramides-1-phosphates ; Glycosylation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -For the design of a synthesis of target molecule 1 the retrosynthetic analysis yielded building blocks 2-5, of which ceramide 2-phosphite derivative 2 and aminoethyl phosphite derivative 5 are known. The generation of α-glucosaminyl (1→6)inositol building block 3 was based on pseudodisaccharide 6 which was selectively benzoylated at 6b-O and then selectively benzylated at 3b-O to give 3. The synthesis of tetramannosyl building block 4 started from known ortho ester derivative 8 which was transformed into versatile mannosyl donors 13 and 18 and into acceptor 22. Reaction of 13 with 22 gave α-disaccharide 23, deacetylation and then mannosylation with 18 gave trisaccharide 25; ensuing deacetylation and mannosylation with 13 gave tetrasaccharide 27; deallylation, acetylation, regioselective removal of the anomeric O-acetyl group and treatment with CCl3CN/DBU afforded 4. Glycosylation of 3 with donor 4 led to pseudohexasaccharide 31 in high yield. Replacement of the O-acyl groups by O-benzyl groups and then exchange of the menthyloxycarbonyl group by an O-acetyl group gave 36 which enabled regioselective attachment of 2 and 5. To this end, the 6e-O-silyl group was removed and then the aminoethyl phosphate residue was attached with reagent 5 to give 38 in high yield. 1a-O-Deacetylation and then reaction with 2 afforded 40 as fully protected 1 which was liberated in two steps; treatment with acid removed all acid labile protective groups and finally catalytic hydrogenation afforded the desired GPI anchor 1 which could be fully structurally assigned.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Modeling the heme vibrational spectrum: Normal-mode analysis of nickel (II) etioporphyrin-I from resonance raman, ft-raman, and infrared spectra of multiple isotopomers (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 1 (1995), S. 395-412 
    Details
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Nearly complete vibrational assignments have been obtained for a heme model, nickel etioporphyrin-I (NiEPI), using variable-wavelength resonance Raman (RR), and FT-Raman (FT-R), as well as infrared (IR) spectroscopy, on a series of isotopomers labeled at positions in the skeleton (15N, β-13C, meso-d4, 15N-meso-d4) and in the peripheral substituents (methyl-d12, ethyl-d8, and ethyl-d12). The vibrational bands are assigned to the porphyrin skeletal and substituent modes on the basis of the mode description scheme developed for nickel octaethylporphyrin (NiOEP) with the aid of a normal-mode analysis of NiEPI, explicitly including the peripheral substituents, i.e., the methyl and ethyl groups. The previously reported NiOEP force field was refined to account for the observed isotope shifts of NiEPI isotopomers. An important result is the requirement of relatively large, long-range force constants for methine bridge bonds on opposite sides of the porphyrin ring. These 1-8 and 1-9 interaction force constants are required to reproduce the frequencies and isotope shifts of six Cα-Cm stretching modes and especially to predict the relative order of the two highest-frequency Eu modes, v(Cα-Cm) (v38, ∼ 1570 cm-1) and v(Cβ-Cβ) (v37, ∼ 1600 cm-1). Most of the substituent (methyl and ethyl) vibrations are located in the RR and IR spectra. Strong RR enhancement of some substituent modes can be attributed to hyperconjugative interaction of the aliphatic groups with the porphyrin a1u orbital, as well as vibrational mixing of substituent modes with the nearby skeletal modes. © 1995 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bspy.350010605
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  • 6
    Electronic Resource
    Electronic Resource
    Heme-protein interactions in cytochrome c peroxidase revealed by site-directed mutagenesis and resonance Raman spectra of isotopically labeled hemes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 2 (1996), S. 365-376 
    Details
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Isotope labeling has been used to assign the resonance Raman spectra of cytochrome c peroxidase, expressed in Escherichia coli [CCP (MKT)], and of the D235N site mutant. 54Fe labeling establishes the coexistence of two separate bands (233 and 246 cm-1), arising from the stretching of the bond between the Fe atom and the proximal histidine ligand, His175. These are assigned to tautomers of the H-bond between the His175 imidazole NΓH proton and the Asp235 carboxylate side chain: In one tautomer the proton resides on the imidazole while in the other the proton is transferred to the carboxylate. When Asp235 is replaced by Asn, the H-bond is lost, and the Fe-His stretching frequency is markedly lowered. Two new RR bands are produced, at 205 and 185 cm-1, as a result of coupling between the shifted Fe-His vibration and a nearby porphyrin mode; the two bands share the 54Fe sensitivity expected for Fe-His stretching. C=C stretching and CβC=C bending vibrations have been separately assigned to the 2- and 4-vinyl groups of the protoheme prosthetic group via selective vinyl deuteration. In the acid form of the enzyme, the frequencies coincide for the two vinyl groups, at 1618 cm-1 for the C=C stretch, and at 406 cm-1 for the CβC=C bend. However, the 2-vinyl frequencies are elevated in the alkaline form of the enzyme, to 1628 cm-1 for C=C stretching, and to 418 cm-1 for CβC=C bending, while the 4-vinyl frequencies remain unshifted. Thus, the acid-alkaline transition involves a protein conformation change that specifically perturbs the 2-vinyl substituent. This perturbation might be a reorientation of the vinyl group, or an alteration of the porphyrin geometry that affects the porphyrin-vinyl coupling. The perturbation is attenuated when CO is bound to the enzyme; the C=C frequency is then unaffected in the alkaline form, while the CβC=C bending frequency is shifted to a smaller extent (412 cm-1). This attenuation is probably linked to inhibition of distal histidine binding to the heme Fe in the alkaline form when the CO is bound. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Structural evolution of the heme group during the allosteric transition in hemoglobin: Insights from resonance raman spectra of isotopically labeled heme (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 2 (1996), S. 311-316 
    Details
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Visible resonance Raman spectra in the low-frequency region (200-500 cm-1) are reported for hemoglobin (Hb) reconstituted with heme that is deuterated at the meso carbon atoms (meso-d4). Spectra were obtained in the deoxy form and in the immediate photoproduct of the carbonmonoxide adduct, HbCO. The isotope shifts permit assignment of two out-of-plane modes, γ6 and γ7, and the in-plane skeletal mode ν8, as well as the well-known iron-histidine [Fe-His] stretching vibration. Important differences between deoxyHb and the immediate photoproduct include 1) a large upshift in the Fe-His frequency, from 216 to 228 cm-1, 2) an upshift in γ6 (349 to 353 cm-1) together with substantial diminution of the ν8 (341 cm-1) intensity, and 3) collapse of two γ7 bands (305 and 296 cm-1) to a single band at 304 cm-1. This last observation implies subunit heterogeneity in deoxyHb but not in the photoproduct. When these bands are monitored in the time-resolved RR spectra following HbCO photolysis, it is seen that subunit heterogeneity is first detectable in the 0.5-μs transient [intermediate S], which has been associated with the initial rearrangement of the subunits to form the T-state contacts, on the basis of ultraviolet RR spectroscopy.1 However the intensification of ν8 does not occur until the 17-μs transient (intermediate T′), in which the T-state contacts are locked in and the Fe-His bond is strained. Implications for the mechanism of Hb allostery are discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Fast atom bombardment tandem mass spectrometry of the anti-parasitic agent pentamidine and its oxygenated metabolites (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 549-556 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Although pentamidine (1,5-bis(4′-amidinophenoxy)pentane) is currently in use for the treatment of a variety of parasitic infections, including acquired immune deficiency syndrome-related Pneumocystis carinii pneumonia, its metabolism is still under investigation. Positive-ion fast atom bombardment mass spectrometry was used with high-energy collision-activated dissociation (CAD) and linked scanning at constant B/E to obtain tandem mass spectra of protonated molecules of pentamindine and seven synthetic oxygenated derivatives, which are known metabolites of pentamidine. Charge-initiated fragmentation produced abundant fragment ions of m/z 120 and 137 and loss of neutral ammonia from the protonated analyte that characterized the amidinophenoxy group. The structures of isomeric 2-hydroxypentamidine, 3-hydroxypentamidine and N-hydroxypentamidine could be distinguished based on charge-remote fragmentation that produced a series of fragment ions of the pentyl chain and permitted the exact location of the hydroxyl group in each molecule to be determined. Next, tandem mass spectra were obtained and the charge-initiated and charge-remote fragmentation discussed for four other metabolites of pentamidine, including N,N′-dihydroxypentamidine, 5-(4′-amidinophenoxy)pentanoic acid, 5-(4′-amidinophenoxy) pentan-1-ol, and p-hydroxybenzamidine. Finally, tandem mass spectrometry was used to identify pentamidine and three pentamidine metabolites contained in high-performance liquid chromatographic (HPLC) fractions from rat liver perfusate and rat urine following treatment with pentamidine. Pentamidine metabolites identified in rat urine and liver perfusate using mass spectrometry and HPLC retention times included 2-hydroxypentamidine, 3-hydroxypentamidine and 5-(4′-amidinophenoxy)pentanoic acid.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300405
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of D-erythro-Ceramide-1-phosphoinositol and Its Aminoglucosylated Derivative - Intermediates in GPI-Anchor Biosynthesis (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 291-298 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Phospholipids ; Glycolipids ; Sphingosines ; Ceramides ; Ceramide-1-phosphates ; Inositols ; Glycophosphosphingolipids, synthesis ; Glycophosphoinositol anchors ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The readily available 2,3:4,5-di-O-cyclohexylidene-D-myo-inositol derivative 3 was converted into the 1-O-unprotected D-myo-inositol derivative 6. Reaction with the phosphite derivative 7 of 3-O-tert-butyldimethylsilyl-protected ceramide furnished the target molecule D-erythro-ceramide-1-phosphoinositol (1). Reaction of O-(3,4,6-tri-O-acetyl-2-azido-β-D-glucopyranosyl)trichloroacetimidate (20) with 3 gave exclusively α(1→6)-connected glycoside 21 which was converted into the 1α-O-unprotected derivative 24. Reaction with the D-erythro-azidophytosphingosine-derived ceramide-1-phosphite derivative 17 led, after oxidation and removal of the cyanoethyl group, to protected 2-azido-D-glucopyranosyl-α(1→6)-D-myo-inositol-1-phospho-ceramide (25) which could be fully deprotected in two steps to afford the target molecule, the ceramide derivative of 2-amino-2-deoxy-D-glucopyranosyl-α(1→6)-D-myo-inositol-1-phosphate (2).
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis Of Labeled Glycosyl Phosphatidyl Inositol (GPI) Anchors (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2563-2571 
    Details
    ISSN: 1434-193X
    Keywords: Carbohydrates ; Phospholipids ; Glycolipids ; Diacylglycerolphosphates ; Glycophosphoinositol anchors ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The exploration of the molecular and structural basis for the sorting of GPI-anchored proteins is based on labeled partial structures of GPI′s which can be incorporated into the GPI anchor biosynthesis and cellular transport systems. To this end, from mannosyl donor 6 and the D-glucosaminyl-(1→6)-D-myo-inositol derivative 7 as acceptor, the pseudotrisaccharide 8 was prepared. Compound 8 was transformed into the GPI partial structures 5a,b which contain the pseudotrisaccharide ligated to two different phosphatidyl residues. Compounds 5a,b have Boc protection at the 2-amino group of the glucosamine residue (2b-position) and a free amino group at the 6b-position. The 6b-amino group was used for the ligation of the 3-(7-nitrobenzofurazan-4-yl)-aminopropanoyl group as a fluorescent label, the 5-azido-2-nitrobenzoyl and 4-azidophenylaminothiocarbonyl groups as photolabels, and the 4-azido-2-hydroxybenzoyl group as a radiolabel after the introduction of radioactive iodine by an electrophilic aromatic substitution. Thus, after acid-catalyzed removal of the protective groups, the unprotected target molecules 1-4 were obtained.
    Type of Medium: Electronic Resource
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