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111.
Recent research has revealed that abscisic acid (ABA), synthesised in response to water stress, is an apo-carotenoid. Two potential carotenoid precursors, 9'- cis -neoxanthin and 9- cis -violaxanthin, have been identified in light-grown and etiolated leaves, and in roots of a variety of species. Experiments utilizing etiolated Phaseolus vulgaris leaves and deuterium oxide strongly suggest that 9'- cis -neoxanthin, synthesised from all- trans -violaxanthin, is the immediate pre-cleavage precursor of ABA. The cleavage of 9'- cis -neoxanthin, performed by an inducible and specific dioxygenase, is likely to be the rate-limiting step in ABA biosynthesis. Any apocarotenoids formed as by-products of cleavage are probably rapidly degraded by lipoxygenase or related enzymes. After cleavage xanthoxin is converted via ABA-aldehyde to ABA by constitutive enzymes in the cytosol. 相似文献
112.
113.
Pea lectin is correctly processed,stable and active in leaves of transgenic potato plants 总被引:5,自引:0,他引:5
Glyn A. Edwards Andrew Hepher Stephen P. Clerk Donald Boulter 《Plant molecular biology》1991,17(1):89-100
A gene encoding the preproprotein of the pea (Pisum sativum) lectin was expressed in transgenic potato plants using a cauliflower mosaic virus (CaMV) 35S promoter or a tobacco ribulose bisphosphate carboxylase small subunit (ssRubisco) promoter. Presence of the pea lectin to levels greater than 1% of total soluble leaf protein was detected by radioimmunoassay (RIA). The pattern of expression derived from the two promoters was established using both RIA and a squash-blot immunolocalisation technique. Western blotting demonstrated that the preproprotein was correctly processed, generating and subunits that assembled to give an isolectin form observed in pea seeds and roots. It was also found that the haemagglutination activity and specificity of pea lectin synthesised in transgenic potato leaves was comparable to purified lectin from pea cotyledons. 相似文献
114.
A protoplast to plant system in roses 总被引:7,自引:0,他引:7
Derek Matthews John Mottley Imelda Horan Andrew V. Roberts 《Plant Cell, Tissue and Organ Culture》1991,24(3):173-180
High yields of protoplasts were isolated from embryogenic suspension cultures of Rosa persica x xanthina and Rosa wichuraiana using an enzyme mixture comprising 20 g l-1 cellulase Onozuka R10, 1 g l-1 Pectolyase Y-23 and 10 g l-1 hemicellulase. Agarose-immobilized protoplasts gave the most consistent growth at a plating density of 5×104 protoplasts ml-1 on the basic medium of Kao & Michayluk (KM8p) containing 2 mg l-1 naphthaleneacetic acid and 1 mg l-1 benzylaminopurine. At 25°C in the dark, 0.004% of R. persica x xanthina protoplasts developed into colonies. Using similar culture conditions, but with a plating density of 9×104 protoplasts ml-1, 0.017% of R. wichuraiana protoplasts developed into colonies. On transfer of R. persica x xanthina colonies to Schenk & Hildebrandt's medium containing 3 mg l-1 2,4-dichlorophenoxyacetic acid, globular and later stage embryos were formed. Approximately 30% of these embryos developed into plantlets on transfer to basal Schenk & Hildebrandt's medium. Further development of the plantlets took place on cellulose plugs (Sorbarods) soaked in Murashige & Skoog's medium containing 0.05 mg l-1 naphthaleneacetic acid, 0.05 mg l-1 indole-3-butyric acid and 0.1 mg l-1 benzylaminopurine. Rose breeding is now open to the full range of in vitro genetic manipulation techniques involving protoplast technology. 相似文献
115.
Elaine F. Smith Andrew V. Roberts John Mottley Susan Denness 《Plant Cell, Tissue and Organ Culture》1991,27(3):309-313
Plantlets of Dendranthema grandiflora Pennine Reel were grown from nodal sections on Sorbarods saturated with liquid medium containing 0–3 mg 1–1 of various growth retardants. After 4 weeks they were transferred to compost and maintained at a relative humidity of 42% at 27.5°C. Wilting was assessed over a period of 3 h. Plantlets treated with paclobutrazol, flurprimidol, triapenthenol, chlorphonium chloride, uniconazol and ancymidol showed dose-related reductions in wilting up to a concentration of 3 mg 1–1. Responses to tetcyclacis and mepiquat chloride were weaker, and no responses to chlormequat chloride, BTS 44584 or diaminozide could be detected. These observations are compatible with an hypothesis that resistance to wilting derives from inhibited synthesis of gibberellins. 相似文献
116.
C. Andrew Cole 《Wetlands Ecology and Management》1992,2(3):135-142
An early successional wetland complex on a reclaimed surface coal mine in southern Illinois was studied 1985–1987. Seasonally, biomass was low, with above-ground values of 10–210g m–2 and below-ground biomass of 1.5–2435 g m–2. Biomass peaked in spring and did not vary much throughout the remainder of the growing season. Stem densities were high (179–1467 m–2) because large numbers of seedlings became established as falling water levels exposed large areas of mudflats. Fluctuating water levels led to a lack of community zonation. Species diversity (H) was low to moderate over all sites with diversity values ranging between 1.86 and 3.27. 相似文献
117.
We have isolated two genomic clones from the murine dystrophin locus, containing single exons encoding protein sequence from the putative actin-binding domain of the amino-terminus and the terminal portion of the triple helical domain. Using interspecific backcross progeny mice, both clones were shown to be X-linked. Sequence analysis indicated that the amino-terminal clone contains a 173 bp exon exhibiting 90% nucleotide sequence identity to human dystrophin exon 6, whilst the C-terminal clone contains a 61 bp exon with 93% nucleotide sequence identity to the human cDNA sequence.
相似文献118.
Lymphocyte activation and serine-esterase induction following recombinant interleukin-2 infusion for lymphomas and acute leukaemias 总被引:3,自引:0,他引:3
Seah H. Lim Colin Worman Andrew Jewell Chris Tsakona Frank J. Giles Anthony Goldstone 《Cancer immunology, immunotherapy : CII》1991,33(2):133-137
Summary C57BL mice inoculated with radiation leukemia virus (RadLV) develop preleukemic cells long before the onset of leukemia. These cells are potentially immunogenic but fail to elicit an immune response in the host because of the appearance of virus-specific suppressor T cells. We have studied the effect of polysaccharide K (PSK) on the generation of RadLV-specific cell-mediated immune responses in vitro. Long-term exposure to PSK in culture potentiated the ability of immunized T cells to respond to a RadLV-induced lymphoma. It also abrogated the suppressive activity of suppressor T cells and simultaneously boosted the ability of reactive T cells to respond. The dual immunostimulating activity of PSK resulted in the generation of T cytotoxic lymphocytes that could lyse lymphoma cells in vitro. The results suggest that PSK could be used as a prophylactic immune response modifier in preleukemia. 相似文献
119.
Jun-mo Chung Andrew N. Spencer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(5):599-606
Summary Dopamine, which is present in nerve-rich tissues of the hydromedusa Polyorchis penicillatus, produces membrane hyperpolarization in identified motor neurons from this jellyfish. In this study we demonstrate that the inhibitory action of dopamine is mediated by conventional drug-receptor interactions which are reversible, saturable and specific. When 10 M dopamine was applied by micro-spritzing onto voltage-clamped (holding potential, –20 mV), cultured swimming motor neurons, an outward current of about 1 nA was evoked. Using this technique, we established a potency order for several amines: dopaminenorepinephrine>tyramine >octopamine>-phenylethylamine. Dopamine is effective at concentrations betweeen 1 × 10-8 and 1 × 10-3
M. Several dopamine receptor blockers such as fluphenazine, haloperidol and spiperone reduced the dopamine-induced current in a concentration-dependent manner. Although propranolol, a -adrenergic blocker, reduced the dopamine response and SKF 83566, a D1 blocker, increased the response, it appears that the dopamine receptors in these jellyfish neurons share pharmacological properties with mammalian D2 dopamine receptors. 相似文献
120.
Dr. Timothy J. Barrett James H. Green Patricia M. Griffin Andrew T. Pavia Stephen M. Ostroff I. Kaye Wachsmuth 《Current microbiology》1991,23(4):189-195
Shiga-like toxin-producingEscherichia coli O157:H7 are important causes of bloody diarrhea and hemolytic uremic syndrome. To facilitate the epidemiologic study of these organisms, we developed enzyme-linked immunosorbent assays (ELISAs) for antibodies to Shiga-like toxin I (SLT I), Shiga-like toxin II (SLT II), andE. coli O157 lipopolysaccharide (LPS). We tested serum samples from 83 patients in two outbreaks ofE. coli O157:H7 diarrhea and from 66 well persons. Forty-three patients (52%) had at least one serum sample positive for anti-O157 LPS antibodies; among 26 culture-confirmed patients, 24 (92%) had at least one positive serum sample. Two (3%) of 66 control sera had positive anti-O157 LPS titers. ELISA results for SLT I and II were compared with those of HeLa cell cytotoxicity neutralization assays on both patient and control sera. Neutralization assays detected anti-SLT I antibodies in at least one serum sample from each of 17 (20%) patients and 7 (10.6%) controls, while 16 (19%) patients and 7 controls had positive titers by anti-SLT I ELISA. Although all serum samples, including control sera, showed nonspecific neutralization of SLT II, no antibody titers to SLT II were detected by either neutralization or ELISA. These results indicate that ELISAs for SLT I and SLT II antibodies are comparable to HeLa cell cytotoxicity neutralization assays. Both the ELISAs and neutralization assays are insensitive in detecting infected patients. However, the ELISA for antibodies toE. coli O157 LPS is both sensitive and specific, and may be more useful than assays for antitoxic antibodies in detecting persons withE. coli O157:H7 infection. 相似文献