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91.
Douglas A. Smyth 《Journal of Plant Growth Regulation》1992,11(2):125-128
Methylxanthine treatment of rice seeds (Oryza sativa L. cv. Lemont) was used to determine the relative efficiencies of caffeine (1,3,7-trimethylxanthine), theobromine (3,7-dimethylxanthine), and theophylline (1,3-dimethylxanthine) as growth regulators in a plant not producing these compounds. Caffeine inhibited growth more effectively than the dimethylxanthines. Treatment with 2.5 mM caffeine inhibited shoot elongation by half after 6 days of growth, and inhibited root elongation by 90% compared to control plants germinated in water. Although caffeine treatment inhibited growth of roots more than shoots, caffeine accumulation was similar in both organs. Apparently, shoots have a more effective mechanism than roots for maintaining growth in the presence of caffeine. 相似文献
92.
Douglas R. Dorer Adom Anane-Firempong Alan C. Christensen 《Molecular & general genetics : MGG》1991,230(1-2):8-11
Summary A locus associated with a severe Minute effect has been mapped at 7C on the X chromosome of Drosophila melanogaster. Previous work has suggested that this Minute encodes ribosomal proteins S14A and S141B. We have made a chromosomal deficiency that removes the S14 ribosomal protein genes, yet does not display the Minute phenotype. These data suggest that the S14 genes do not actually correspond to the Minute locus. 相似文献
93.
The Late-Triassic-dinosaur generic nameCoelophysis Cope 1889 (type species C.bauri [Cope 1887]) is a nomen dubium because the lectotype of C.bauri, AMNH 2722, is four sacral vertebrae and a pubic process of the ilium that are not diagnostic. Dinosaur specimens from the famous Whitaker (“Coelophysis”) quarry in the Rock Point Member of the Chinle Formation at Ghost Ranch, New Mexico thus lack a valid name. We create a new genus and species name,Rioarribasaurus colberti, for these specimens. 相似文献
94.
The major albumin, a polypeptide of 21 kilodaltons (kDa), from the seeds of cocoa (Theobroma cacao L.), has been identified and partially purified by preparative gel electrophoresis. Some N-terminal sequence was obtained, permitting the construction of an oligonucleotide probe. This probe was used to isolate the corresponding copy DNA (cDNA) clone from a library made from poly(A)+ RNA from immature cocoa beans. The cDNA sequence has a single major open reading frame, that translates to give a 221-amino-acid polypeptide of Mr 24003. The existence of a precursor to the 21-kDa polypeptide of this size was confirmed by immunoprecipitation from total poly(A)+ RNA translation products. The polypeptide has a hydrophobic signal sequence of 26 amino acids before the mature start, and the mature polypeptide would have an Mr of 21223. The protein sequence is homologous with sequences of the Kunitz protease and -amylase inhibitor family, and the protein probably functions to defend the seed's protein reserves from the digestive enzymes of invading pests. However because the protein comprises 25–30% of the total seed protein it may itself also function as a storage protein. Electron micrographs of immunogold-labelled embryo sections show that the protein is located in membrane-enclosed organelles.Abbreviations cDNA
copy DNA
- IgG
immunoglobulin G
- kb
kilobase pairs
- kDa
kilodaltons
- Mr
relative molecular mass
- SDS-PAGE
sodium dodecyl sulphate-polyacylamide gel electrophoresis
The authors are very grateful to Dr R. Jennings of the Virology Department, Sheffield University Medical School, for help in raising antibodies, and to Dr G. Cope, of the Biological Sciences Electron Microscopy Unit, Sheffield University, for taking the electron micrographs.To whom correspondence should be addressed. 相似文献
95.
Gerard H. Markx Christopher L. Davey Douglas B. Kell Phillip Morris 《Journal of biotechnology》1991,20(3):279-290
A novel technique is described for the measurement of the volume fraction of biomass in a suspension by the simultaneous measurement of the conductivity of a suspension containing cells and of the medium in which the cells are suspended. The presence of non-conducting particulate matter in a suspension will cause the conductivity of a suspension to be decreased relative to that of the medium in which the particles are suspended. A simple equation (the Bruggeman equation) describes the relationship between the volume fraction of non-conducting particulate matter and the decrease in conductivity. The accuracy of this method for the determination of the biomass concentration of plant cells (Festuca arundinacea) in culture was shown. The method was successfully applied to the on-line determination of biomass concentrations during the growth of F. arundinacea cultures, and gave good agreement with biomass levels as determined from measurements of the radio-frequency dielectric permittivity of such cultures. 相似文献
96.
97.
A. J. Swerdlow A. J. Douglas G. V. Hudson B. V. Hudson M. H. Bennett K. A. MacLennan 《BMJ (Clinical research ed.)》1992,304(6835):1137-1143
OBJECTIVE--To analyse the risk of second primary cancers during long term follow up of patients with Hodgkin''s disease. DESIGN--Cohort study. SETTING--The British National Lymphoma Investigation (a collaborative group of over 60 participating centres in Britain treating lymphomas). PATIENTS--2846 patients first treated for Hodgkin''s disease during 1970-87, for whom follow up was complete in 99.8%. MAIN OUTCOME MEASURES--Second primary cancers; uniform pathology reviews confirmed the diagnosis of Hodgkin''s disease and of second primary non-Hodgkin''s lymphomas. RESULTS--113 second primary cancers occurred. Relative risk of cancer other than Hodgkin''s disease was 2.7 (95% confidence interval 2.3 to 3.3) compared with the general population, with significant risk of leukaemia (16.0(9.1 to 26.0)); non-Hodgkin''s lymphoma (16.8(9.8 to 26.9)); and cancers of the colon (3.2 (1.4 to 6.2)), lung (3.8 (2.6 to 5.4)), bone (15.1 (1.8 to 54.7)), and thyroid (9.4 (1.1 to 33.9)). Absolute excess risk associated with treatment was greater for solid tumours than for leukaemia and lymphomas. Relative risk of leukaemia increased soon after treatment, reaching a peak after five to nine years. It was increased substantially after chemotherapy (27.9 (12.7 to 52.9)), combined treatment with radiotherapy and chemotherapy (21.5 (7.9 to 46.8)), and relative to number of courses of chemotherapy but was not significantly increased after radiotherapy (2.5 (0.1 to 14.1)). Relative risk of non-Hodgkin''s lymphoma increased in the first five years after treatment and remained high but showed no clear relation with type or extent of treatment. Relative risk of solid tumours was less raised initially but increased throughout follow up and for lung cancer 10 years or more after entry was 8.3 (4.0 to 15.3). The risk of solid tumours increased after treatments including radiotherapy and after chemotherapy alone. The risk after chemotherapy increased significantly with time since first treatment. CONCLUSION--The risk of solid cancer, not of leukaemia, is the major long term hazard of treatment for Hodgkin''s disease, and this seemed to apply after chemotherapy as well as after radiotherapy. These risks of second cancers are important in choice of treatment and in follow up of patients, but they are small compared with the great improvements in survival which have been brought about by modern therapeutic methods for Hodgkin''s disease. 相似文献
98.
Exonic sequences are required for elicitor and light activation of a plant defense gene, but promoter sequences are sufficient for tissue specific expression. 总被引:13,自引:1,他引:12
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C J Douglas K D Hauffe M E Ites-Morales M Ellard U Paszkowski K Hahlbrock J L Dangl 《The EMBO journal》1991,10(7):1767-1775
99.
100.
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