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71.
Carol Anelli Sheppard Marcia J. Loeb 《Archives of insect biochemistry and physiology》1992,21(3):179-193
A subcellular fraction enriched in plasma membranes was obtained from gypsy moth (Lymantria dispar) larval midgut tissue. Using [45Ca]2+ as a tracer, Ca2+ transport activity by membrane vesicles in the enriched fraction was measured and shown to be ATP-dependent, with a very high affinity for Ca2+ (apparent Km for [Ca2+ free] 1 Abbreviations used: [Ca2+free] = concentration of free (unbound) calcium ion;CaM = calmodulin; F = fraction; IOV = inside-out membrane vesicles; W-5 = N-(6-aminohexyl)-1-naphthalenesulfonamide; W-7 = N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide. = 22 nM). Ca2+ transport was abolished upon addition of the calcium ionophore, A23187. Ca2+-stimulated, Mg2+-dependent ATPase activity peaked between 100 and 200 nM Ca2+free. Ca2+-Mg2+-ATPase activity was inhibited by vanadate, 2 phenothiazine drugs (trifluoperazine and chlorpromazine), and the naphthalene sulfonamide, W-7; the related compound, W-5, and ouabain had a negligible effect. These results suggest the presence of a high affinity plasma membrane Ca2+ pump in gypsy moth larval midgut cells and are discussed in light of earlier work involving calcium transport in isolated midguts of larval Hyalophora cecropia. Ionic and other conditions that characterize the midgut physiology of larval Lepidoptera (e.g., luminal pH; electrochemical gradient for Ca2+; effect of certain ions and inhibitors on Ca2+ transport) contrast significantly with those found in adult Diptera. The implications that these differences may have for calcium regulation are discussed. © 1992 Wiley-Liss, Inc. 相似文献
72.
Carbon and nitrogen isotope ratios in different compartments of a healthy and a declining Picea abies forest in the Fichtelgebirge,NE Bavaria 总被引:4,自引:0,他引:4
Summary Natural carbon and nitrogen isotope ratios were measured in different compartments (needles and twigs of different ages and crown positions, litter, understorey vegetation, roots and soils of different horizons) on 5 plots of a healthy and on 8 plots of a declining Norway spruce (Picea abies (L.) Karst.) forest in the Fichtelgebirge (NE Bavaria, Germany), which has recently been described in detail (Oren et al. 1988a; Schulze et al. 1989). The 13C values of needles did not differ between sites or change consistently with needle age, but did decrease from the sun-to the shade-crown. This result confirms earlier conclusions from gas exchange measurements that gaseous air pollutants did no long-lasting damage in an area where such damage was expected. Twigs (13C between-25.3 and-27.8) were significantly less depleted in 13C than needles (13C between-27.3 and-29.1), and 13C in twigs increased consistently with age. The 15N values of needles ranged between-2.5 and-4.1 and varied according to stand and age. In young needles 15N decreased with needle age, but remained constant or increased in needles that were 2 or 3 years old. Needles from the healthy site were more depleted in 15N than those from the declining site. The difference between sites was greater in old needles than in young ones. This differentiation presumably reflects an earlier onset of nitrogen reallocation in needles of the declining stand. 15N values in twigs were more negative than in needles (-3.5 to-5.2) and showed age- and stand-dependent trends that were similar to the needles. 15N values of roots and soil samples increased at both stands with soil depth from-3.5 in the organic layer to +4 in the mineral soil. The 15N values of roots from the mineral soil were different from those of twigs and needles. Roots from the shallower organic layer had values similar to twigs and needles. Thus, the bulk of the assimilated nitrogen was presumably taken up by the roots from the organic layer. The problem of separation of ammonium or nitrate use by roots from different soil horizons is discussed. 相似文献
73.
Viqar Uddin Ahmad Mohammad Ghani Shah Faryal Vali Mohammad Nargis Ismail Mushtaq Noorwala 《Phytochemistry》1991,30(12)
A new flavone glucoside macrophylloside has been isolated from the whole plant of Primula macrophylla and its structure was determined by spectroscopic methods as 2′-hydroxy-7-O-β-
-glucopyranosyloxyflavone. Sitosterol glucoside was also isolated for the first time from this plant. 相似文献
74.
Targeting of T7 RNA polymerase to tobacco nuclei mediated by an SV40 nuclear location signal 总被引:9,自引:0,他引:9
Michael W. Lassner Aubrey Jones Steve Daubert Luca Comai 《Plant molecular biology》1991,17(2):229-234
We have expressed two T7 RNA polymerase genes by electroporation into tobacco protoplasts. One of the genes was modified by inserting nucleotides encoding a viral nuclear localization signal (NLS) from the large T antigen of SV40. Both T7 RNA polymerase genes directed synthesis of a ca. 100 kDa protein in the electroporated protoplasts. T7 RNA polymerase activity was detected in extracts of protoplasts electroporated with both genes. Immunofluorescence analysis of these protoplasts indicated that only the polymerase carrying the NLS accumulated in the cell nucleus. These experiments suggest that mechanisms involved in the transport from the cytoplasm to the nucleus are similar in plant and animal cells. This system demonstrates the feasibility of T7 RNA polymerase-based approaches for the high-level expression of introduced genes in plant cells. 相似文献
75.
High-level expression of a tobacco chitinase gene in Nicotiana sylvestris. Susceptibility of transgenic plants to Cercospora nicotianae infection 总被引:12,自引:0,他引:12
Jean-Marc Neuhaus Patricia Ahl-Goy Ursula Hinz Susan Flores Frederick Meins Jr. 《Plant molecular biology》1991,16(1):141-151
Endochitinases (E.C. 3.2.14, chitinase) are believed to be important in the biochemical defense of plants against chitin-containing fungal pathogens. We introduced a gene for class I (basic) tobacco chitinase regulated by Cauliflower Mosaic Virus 35S-RNA expression signals into Nicotiana sylvestris. The gene was expressed to give mature, enzymatically active chitinase targeted to the intracellular compartment of leaves. Most transformants accumulated extremely high levels of chitinase-up to 120-fold that of non-transformed plants in comparable tissues. Unexpectedly, some transformants exhibited chitinase levels lower than in non-transformed plants suggesting that the transgene inhibited expression of the homologous host gene. Progeny tests indicate this effect is not permanent. High levels of chitinase in transformants did not substantially increase resistance to the chitin-containing fungus Cercospora nicotiana, which causes Frog Eye disease. Therefore class I chitinase does not appear to be the limiting factor in the defense reaction to this pathogen. 相似文献
76.
A system was devised for the in vitro culture of soybean fruits. The culture system consisted of a single fruit attached to a short piece of stem through which the nutrients were supplied. The fruit explants were taken when pods were fully expanded and the seeds at initial stages of growth. During a 7-day culture period, the seeds accumulated dry matter and protein in quantities comparable to those in situ. Omission of the C source (sucrose) from the medium resulted in no dry matter accumulation in the seeds, but omission of the N source (glutamine) still led to some protein accumulation, indicating mobilization of N from other parts of the fruit explant. Optimum protein accumulation occurred when glutamine was supplied at 1.2 mg N ml-1. Protein accumulation in the seeds was highly dependent on the nature of the N source. Glutamine, asparagine and the ureide, allantoin, were equally the most efficient sources, whereas several other amino acids tested showed lower degrees of efficiency. The data indicate a high metabolic capacity of the fruit tissues for principal N transport compounds of soybean, namely allantoin, asparagine and glutamine. The culture system described should prove useful for developmental and metabolic studies where the complex influence of the rest of the plant is to be avoided.Abbreviations ALN
allantoin
- ALC
allantoic acid
Preliminary report presented at the IV World Soybean Research Conference, Buenos Aires, Arggentina, March 1989. 相似文献
77.
Jan A. Veenstra 《Peptides》1991,12(6):1285-1289
An ELISA for corazonin, a cardioactive neuropeptide from the American cockroach, Periplaneta americana, was developed. It was used to isolate corazonin from the cockroach Nauphoeta cinerea, the locust Schistocerca americana, and the hawkmoth Manduca sexta. The peptides from Nauphoeta and Manduca had the same retention times as Periplaneta corazonin, and their amino acid compositions also suggested that these peptides are identical with corazonin. The corazonin-immunoreactive peptide from Schistocerca eluted slightly earlier on HPLC than corazonin, and its structure was determined to be [His7]corazonin, or pGlu-Thr-Phe-Gln-Tyr-Ser-His-Gly-Trp-Thr-Asn-amide. These results indicate that corazonin is generally present in insects and that its structure has been well conserved. 相似文献
78.
Karl Hård Albert Mekking Johannis P. Kamerling Georges A. A. Dacremont Johannes F. G. Vliegenthart 《Glycoconjugate journal》1991,8(1):17-28
Five brain-derived and 17 urinary oligomannose-type oligosaccharides were isolated by ion-exchange chromatography on Mono Q or Dowex, followed by HPLC on Lichrosorb-NH2 from a Persian cat suffering from -mannosidosis. The structures ofthe carbohydrate chains were determined by 500- or 600-MHz1H-NMR spectroscopy. Different oligosaccharide patterns were found in brain and urine. 99% of the urinary oligosaccharides possess an (1-6)-linked mannose residue attached to -mannose, whereas only 5% of the brain-derived oligosaccharides contain such a residue. Furthermore, of the urinary carbohydrate chains 71% end with Man1-4GlcNAc1-4GlcNAc and 29% end with Man1-4GlcNAc, whereas the corresponding amounts are 23% and 77%, respectively, for the brain-derived oligosaccharides.Abbreviations MLEV-17
composite pulse devised by M. Levitt
- HOHAHA
homonuclear Hartman-Hahn spectroscopy
- TPPI
time-proportional phase incrementation
- 2D
two dimensional
- GlcNAc
N-acetylglucosamine
- Man
mannose
- Fuc
fucose 相似文献
79.
S. Frillingos M. Frangou-Lazaridis K. Seferiadis J. D. Hulmes Y. -C. E. Pan O. Tsolas 《Molecular and cellular biochemistry》1991,108(1):85-94
Goat prothymosin , a highly acidic polypeptide of pl 3.5, 109 amino acid residues, has been isolated from lymphoid and non-lymphoid tissues of young female goats. Unlike rat, murine and porcine prothymosins , goat prothymosin appears at a higher concentration in the spleen compared with the thymus. The sequence of segments of the polypeptide involving known mutations has been determined, by automatic sequencing of its tryptic peptide fragments. The acidic amino acid-rich segment in the middle of the molecule, including residues 49–83, has not been sequenced. Goat prothymosin closely resembles bovine prothymosin , with only one substitution, proline for alanine at position 85. It also resembles human prothymosin , with only three substitutions. It differs more significantly from rat and murine prothymosins , by two deletions and three substitutions. The results show the highly conserved nature of the molecule, with substitutions at given positions only.Abbreviations ProT
Prothymosin
- T1
Thymosin 1
- MLR
Mixed Lymphocyte Response
- HPLC
High Performance Liquid Chromatography
- RIA
Radioimmunoassay
- B
Aspartic acid or Asparagine
- Z
Glutamic acid or Glutamine 相似文献
80.
Rolf Altenburger Sibylle Abarzua Rainer Callies L. Horst Grimme Adalbert Mayer Dieter Leibfritz 《Archives of microbiology》1991,156(6):471-476
Cultures of the cyanobacterium Microcystis firma show rhythmic uptake and release of ammonia under conditions of carbon limitation. The massive removal of ammonia from the medium during the first light phase has little impact on the intracellular pH: a pH shift of less than 0.2 U towards the alkaline can be measured by in vivo 31P NMR. Furthermore, the energy status of the cells remains regulated. In vivo 15N NMR of M. firma, cultivated either with labelled nitrate or ammonia as the sole nitrogen source, reveals only gradual differences in the pool of free amino acids. Additionally both cultivation types show -aminobutyric acid, acid amides and yet unassigned secondary metabolites as nitrogen storing compounds. Investigating the incorporation of nitrogen under carbon limitation, however, only the amide nitrogen of glutamine is found permanently labelled in situ. While transamination reactions are blocked, nitrate reduction to ammonia can still proceed. Cation exchange processes in the cell wall are considered regarding the ammonia disappearance in the first phase, and the control of ammonia uptake is discussed with respect to the avoidance of intracellular toxification.Abbreviations GABA
-aminobutyric acid
- GOGAT
glutamate synthase
- GS
glutamine synthetase
- MDP
methylene diphosphonate
- MOPSO
3-(N-morpholino)-2-hydroxy-propanesulfonic acid
- NDPS
nucieoside diphosphosugars
- NOE
nuclear Overhauser effect
- NMR
nuclear magnetic resonance
For convenience, the term ammonia is used throughout to denote ammonia or ammonium ion when there is no good evidence as to which chemical species is involved 相似文献