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171.
The interaction of a vesicular-arbuscular mycorrhizal fungusGlomus fasciculatum with a wilt-causing soil borne pathogen,Fusarium oxysporum, was studied in cowpea (Vigna unguiculata). It was found that pre-establishment by vesicular-arbuscular mycorrhizal fungus reduced the colonization of the pathogen and
the severity of the disease, as determined by reduction in vascular discolouration index. In mycorrhizal plants, the production
of phytoalexin compounds was always higher than in the nonmycorrhizal plants. There appeared to be a direct correlation between
the concentration of the phytoalexins and the degree of mycorrhizal association. Three different compounds withR
f values of 0.23 (I), 0.17 (II) and 0.11 (III) were obtained from mycorrhizal plants. Similar compounds were also found to
be induced by an abiotic elicitor CuSO4. The first compound was identified as an isoflavonoid, daidzein and the other two remain to be identified. These compounds
were checked for their antifungal activityin vitro. The germination of conidial spores ofFusarium oxysporum was strongly inhibited by the compound III than the other two. It is argued that the production of phytoalexin compounds
in mycorrhizal plant could be one of the mechanisms imparting tolerance of the plants to wilt disease. 相似文献
172.
C. Den Hartog 《Aquatic Ecology》1994,28(1):51-54
In the archives of the State Institute of Fisheries Research a handwritten report of A. van der Werff on the wasting disease
ofZostera marina L. in the Waddensea in 1932 and 1933 is kept. It contains an eye-witness account of the decline of the eelgrass beds. In
1932 the first attack of the disease took place in May and caused heavy devastation. Regeneration started soon, but a second
attack at the end of August seemed to destroy the beds definitively. The next year was a year of struggle for the few poorly
developed surviving plants. In 1938 the last surviving specimens were seen in the sublittoral. 相似文献
173.
Bulb canker of garlic caused byEmbellisia allii was newly detected in Japan. Symptoms of the disease are described and the morphological characteristics of the causal fungus are illustrated and described. 相似文献
174.
鸡马立克氏病病毒B抗原片段在大肠杆菌中表达 总被引:1,自引:0,他引:1
鸡马立克氏病病毒BamHI基因文库I3质粒中含有编码B抗原膜外Domain的DNA序列。经ScaI和SphI双酶酶解I3质粒,分离获得764bpDNA片段,并克隆进M13mp19中。DNA序列测定分析表明克隆片段为MDV-B抗原基因的494-1258bp部分序列。进一步分离NcoI-HindIII部分基因片(530bp),克隆于PLPromoter控制下的含有修饰型cIts857基因的表达载体中, 相似文献
175.
Franz Hefti 《Developmental neurobiology》1994,25(11):1418-1435
The ability of neurotrophic factors to regulate developmental neuronal survival and adult nervous system planticity suggests the use of these molecuales to treat neurodegeneration associated with human diseases. Solid rationales exist for the use of NGF and neurotrophin-3 in the treatment of neuropathies of the peripheral sensory system, insulin-like growth factor and ciliary neurotrophic factor in motor neuron atrophy, and NGF in Alzheimer's disease. Growth factors have been identified for neurons affected in Parkinson's disease, Huntington's disease, and acute brain and spinal cord injury. Various strategies are actively pursued to deliver neurotrophic factors to the brain, and develop therapeutically useful molecules that mimic neurotrophic factor actions or stimulate their production or receptor mechanisms. 1994 John Wiley & Sons, Inc. 相似文献
176.
177.
降钙素基因相关肽的研究进展 总被引:1,自引:0,他引:1
吴祥声 《氨基酸和生物资源》1994,(1)
降钙素基因相关肽(CGRP)是由37个氨基酸残基构成的生物活性多肽,与降钙素(CT)源子一个共同的基因。CGRP分布广泛,具有很强的血管扩张、降低血压以及心肌正性肌力作用等,并参与心血管系统稳态的调节。目前,CGRP已能人工合成,将为某些心血管疾病如高血压、心肌缺血、痉挛性或闭塞性周围血管疾病等的治疗提供一条崭新的途径。 相似文献
178.
《微生物学免疫学进展》1994,(2)
重组BCG口服免疫诱导的细胞和体液免疫应答最近研究证明,外源基因能在牛分枝杆菌BCG中表达,用这些重组分枝杆菌免疫小鼠可诱导抗外来蛋白的细胞和抗体免疫应答。近年来的许多研究也证实了肠道和呼吸道粘膜淋巴系统在防御感染方面的贡献,因此,迫切需要能够刺激粘... 相似文献
179.
Striatal L-DOPA Decarboxylase Activity in Parkinson's Disease In Vivo: Implications for the Regulation of Dopamine Synthesis 总被引:3,自引:0,他引:3
Albert Gjedde Gabriel C. Léger Paul Cumming Yoshifumi Yasuhara Alan C. Evans Mark Guttman Hiroto Kuwabara 《Journal of neurochemistry》1993,61(4):1538-1541
Abstract: L-DOPA is a large neutral amino acid subject to transport out of, as well as into, brain tissue. Competition between dopamine synthesis and L-DOPA egress from striatum must favor L-DOPA egress if decarboxylation declines relatively more than transport in Parkinson's disease. To test this hypothesis, we injected patients with Parkinson's disease with a radidabeled analogue of L-DOPA and recorded regional brain radioactivity as a function of time by means of positron emission tomography. We simultaneously estimated the activity of the decarboxylating enzyme and the amino acid transport. In the striatum of patients, we found the L-DOPA decarboxylase activity to be reduced in the head of the caudate nucleus and the putamen. However, the rate of egress of the DOPA analogue was unaffected by the disease and thus inhibited dopamine synthesis more than predicted in the absence of L-DOPA egress. 相似文献
180.
A. Kastner E. C. Hirsch M. T. Herrero F. Javoy-Agid Y. Agid 《Journal of neurochemistry》1993,61(3):1024-1034
Abstract: Parkinson's disease is characterized by massive degeneration of the melanized dopaminergic neurons in the substantia nigra. The functional capacity of the surviving nigral neurons is affected, as indicated by the subnormal levels of tyrosine hydroxylase (TH) mRNA in these neurons and the presence in the parkinsonian mesencephalon of melanized neurons lacking TH immunoreactivity. This is apparently in contradiction with the known overactivity of dopamine synthesis and release that occurs in the remaining dopaminergic terminals. To test the ability of the surviving neurons to express TH protein, a semiquantitative immunocytochemical method was developed. The relative amounts of TH were estimated with a computer-assisted image analysis system in the dopaminergic neurons of representative mesencephalic sections of control and parkinsonian brains and for comparison in brains from patients with Alzheimer's disease. In control brains, the mean TH content per neuron differed from one subject to another and between the different dopaminergic cell groups of the mesencephalon in the same subject. Within a given dopaminergic region, the level of TH was variable among neurons. In patients with Parkinson's disease, the ratio of TH protein content per neuron in the substantia nigra by reference to that of the central gray substance was reduced. In patients with Alzheimer's disease, the amount of TH was selectively reduced in the remaining dopaminergic neurons of the ventral tegmental area, a region characterized by a loss in dopaminergic neurons. The decrease in cellular TH content might therefore be related to the presence of the neurodegenerative process in the area considered. In patients with Parkinson's disease, the incapacity of the surviving neurons to express normal TH levels may reduce the efficiency of the hyperactivity mechanisms that develop in the remaining striatal dopaminergic terminals. 相似文献