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Folylpolyglutamates in Leishmania major   总被引:3,自引:0,他引:3  
The intracellular folates of the protozoan parasite Leishmania major have been examined. About 95% of the exogenous [3H]folate accumulated by the protozoan is metabolized to polyglutamate conjugates within 65 hr, and the intracellular folates are about forty-fold concentrated over the folate in the medium. The predominant metabolite of folic acid is the pentaglutamate conjugate (85%), with lessor amounts of the tetraglutamate (approximately 9%) and hexaglutamate (approximately 3%), and trace (less than 2.5%) amounts of di-, tri- and hepta-glutamate conjugates. Chromatographic properties of the products indicate that the conjugates are linked through the gamma-carboxyl groups. The folylpolyglutamate distribution in Leishmania is similar to that found in mammalian tissues.  相似文献   

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P. lanceolata andP. major were grown in culture solutions with nitrate or ammonium as the nitrogen source. Dry matter accumulation in the shoot was faster with nitrate than with ammonium, whilst that of the roots was not affected by the nitrogen source. As a consequence, the shoot-to-root ratio was lower with ammonium than with nitrate. InP. lanceolata, dry matter percentage of shoot and root tissue was lower with nitrate nutrition, suggesting better elongation growth than with ammonium. However, in shoot tissue ofP. major the opposite was found. The rate of root respiration declined with time, and this was almost completely due to a declining activity of the alternative path, which amounted to about 30–60% of total root respiration. Respiration via the cytochrome path was for a part of time slightly increased by ammonium, whereas the activity of the alternative path was strongly enhanced. The concentration of ethanol-soluble carbohydrates (SC) in the roots of both species was higher when nitrate was used, but no difference in the concentration of starch was found. When the plants were transferred from one nitrogen source to the other, many parameters, including the concentration of nitrate and chloride, and the shoot to root ratio, adjusted to the new situation in both species. Grassland Species Research Group, Publication no. 116.  相似文献   

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Existing knowledge shapes our understanding of ecosystems and is critical for ecosystem-based management of the world''s natural resources. Typically this knowledge is biased among taxa, with some taxa far better studied than others, but the extent of this bias is poorly known. In conjunction with the publically available World Registry of Marine Species database (WoRMS) and one of the world''s premier electronic scientific literature databases (Web of Science®), a text mining approach is used to examine the distribution of existing ecological knowledge among taxa in coral reef, mangrove, seagrass and kelp bed ecosystems. We found that for each of these ecosystems, most research has been limited to a few groups of organisms. While this bias clearly reflects the perceived importance of some taxa as commercially or ecologically valuable, the relative lack of research of other taxonomic groups highlights the problem that some key taxa and associated ecosystem processes they affect may be poorly understood or completely ignored. The approach outlined here could be applied to any type of ecosystem for analyzing previous research effort and identifying knowledge gaps in order to improve ecosystem-based conservation and management.  相似文献   

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Cassane diterpenoid from Caesalpinia major   总被引:1,自引:0,他引:1  
A new cassane diterpenoid, 14-deoxy-epsilon-caesalpin was isolated from the seed kernels of Caesalpinia major and its structure was determined by spectroscopic data.  相似文献   

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The features of dermatoglyphics in 39 children with beta-thalassemia major and in 47 their parents are studied. The control were 70 healthy children. The patients with beta-thalassemia had more often the prevailence of whorls over other finger patterns. There was an increase of the "atd" angle and some increase in the ridge of counts. Parents had also an increase of the amount of whorls, but this increase was less pronounced than under beta-thalassemia. The changes of the dermatoglyphics in parents of children affected with beta-thalassemia major are suggested to ba a phenotypic feature of heterozygous carrier of the mutant gene.  相似文献   

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Many lines of evidence indicate that in recent: years the focus of evolutionary biology has begun to shift from explaining the 'origin of species' to the modelling of processes by which autonomous entities cooperate (or are coerced) to form systems of greater complexity. If such a major shift is indeed occurring, then it should be more widely promulgated to counteract the public image of evolutionary theory, which appears to be as dogmatically simplistic today as it was a century ago.  相似文献   

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Autophagy is a core molecular pathway for the preservation of cellular and organismal homeostasis. Pharmacological and genetic interventions impairing autophagy responses promote or aggravate disease in a plethora of experimental models. Consistently, mutations in autophagy‐related processes cause severe human pathologies. Here, we review and discuss preclinical data linking autophagy dysfunction to the pathogenesis of major human disorders including cancer as well as cardiovascular, neurodegenerative, metabolic, pulmonary, renal, infectious, musculoskeletal, and ocular disorders.  相似文献   

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Escitalopram is the purified functional isomer contained in citalopram. Escitalopram is now prescribed in 26 countries. In the United States, the only US Food and Drug Administration (FDA)-approved selective serotonin reuptake inhibiter (SSRI) for adolescents is fluoxetine. However, in clinical practice all antidepressants are used in adolescents. Five patients had parents who opted for the use of escitalopram instead of other treatments. Reasons included poor response and side effects from other SSRIs. Specifically, escitalopram was considered possibly less likely to cause obesity than paroxetine. It also caused a lower frequency of akathisia than fluoxetine, more stable blood levels over years than sertraline, very low drug interactions, and a low onset of anxiety if using a 5-mg starting dose. Although studies in adolescents are very limited for escitalopram, its parent medication--citalopram--has been used in over 40 million patients. Parents and adolescent patients should be made aware of all antidepressant options, if psychopharmacology is indicated. In some patients, escitalopram may have use.  相似文献   

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婚配制度作为一种进化稳定对策是动物对某一环境包括种群内部环境适应的结果,在动物生殖过程中具有重要意义.大山雀(Parus major)是一种广域分布物种,研究显示广域分布物种的形态、生理、行为、生态特征及婚配制度在不同地区或种群间存在显著差异,因此,该文选择了分布于中国辽宁仙人洞国家级自然保护区的大山雀(P.m.minor)种群开展其婚配制度研究.野外共采集了22巢大山雀亲代和子代血液样本.结果如下:(1)从11个微卫星位点中筛选出了8个多态性较好的微卫星位点用于大山雀父权鉴定,在母本已知的情况下确定父权的准确率可达99.98%;(2)巢内父权鉴定结果显示,31.8% (7/22)的巢包含婚外父权,8.12% (16/197)的子代为婚外子代.与其他森林雀形目鸟类相比,大山雀婚外子代的比例明显偏低(<10%),每个存在婚外父权巢的婚外子代比例各异(55.6%~9.1%),且无明显规律.  相似文献   

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