首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
The bark of Nauclea parva contains several alkaloids, the most abundant of which, parvine, is of the corynanthé-type. The proof of structure of this alkaloid is given and its synthesis from harmalan and nicotinoyl chloride is described.  相似文献   

2.
Peripheral blood leucocytes (PBL) of cattle were infected in vitro with the sporozoites of Theileria parva spp. The transformed cell lines were adapted to grow in sera from the PBL donors. The cattle were then infected with T. p. parva stabilate and either treated with parvaquone or the disease allowed to run its course. Sera harvested during severe disease reaction or early recovery were substituted for pre infection sera and caused the intracellular degeneration of the Theileria macroschizonts. Cell lines passaged in these sera died out as the parasites were eliminated. The antiparasitic effects of sera were short lived and were neither host nor parasite isolate restricted.  相似文献   

3.
4.
Nitrate reductase of the salt tolerant alga Dunaliella parva, in contrast to that of most green algae, can use NADPH as well as NADH as electron donor. Extracts of cells contained various amounts of latent nitrate reductase. The latent enzyme could be activated at 45°C but only in the presence of flavine adenine dinucleotide. The heat activated enzyme did not require flavine adenine dinucleotide for activity and was fully active with NADH, NADPH or reduced flavine mononucleotide as electron donors.  相似文献   

5.
Recent technological developments in the field of genome analyses have advanced our knowledge of the structures of prokaryotic and eukoryotic genomes. Examples of these range from small bacterial genomes, such as Escherichia coli, to the more complex genomes of Caenorhabditis elegans, Drosophila, humans and mouse. Here, Subhash Morzona and John Young review developments in mapping the genome of on economically important protozoan parasite o f cattle, Theileria parva. This map provides a framework for more detailed analysis of the genome structure o f this organism. The methodologies developed in constructing the map also have application to the mapping of other protozoan genomes.  相似文献   

6.
The extremely halotolerant green alga, Dunaliella parva, tolerates salt concentrations from 0.3 to 3.0 M NaCl. Effects of long-term adaptation to five distinct salinities were analyzed. Salt-dependent differences of physiological parameters such as growth rate, pigments, quantitative protein contents, and gas exchange were measured; furthermore the qualitative protein composition in salt-adapted cells was investigated using SDS-polyacrylamide gel electrophoresis. Proteins of apparent molecular masses of 26, 35, 39, 50, and 63 kDa were induced or intensified with an increase in external sodium chloride concentration whereas proteins of 85 and 101 kDa were diminished in high salt algae. After selective staining, four modifications of glycoproteins were observed. A glycoprotein of 96 kDa was produced exclusively in low salt cells whereas glycosylations of 105, 135, and 260 kDa were induced by high salt concentrations.  相似文献   

7.
Dihydroxyacetone Kinase Activity in Dunaliella parva   总被引:3,自引:1,他引:2       下载免费PDF全文
An enzyme catalyzing the phosphorylation of dihydroxyacetone has been identified in the halophilic alga, Dunaliella parva. Since glycerol and glyceraldehyde are not substrates, the enzyme is referred to as dihydroxyacetone kinase. Dihydroxyacetone kinase was purified 9-fold by ammonium sulfate fractionation followed by DEAE-cellulose chromatography.  相似文献   

8.
Theileria parva: kinetics of replication   总被引:5,自引:0,他引:5  
  相似文献   

9.
East Coast fever, which is caused by Theileria parva infection in cattle, is of major economic importance in eastern and central Africa. Until recently, the only available method of immunization against East Coast fever was the infection with live sporozoites and simultaneous treatment with a long-acting oxytetracycline. This method has two major disadvantages: (I) it uses live organisms; and (2) the immunity engendered is parasite strain specific. In this article, Antony Musoke, Vishvonath Nene and Subhosh Morzoria review the progress made in developing an alternative method o f immunization based on a defined sporozoite antigen.  相似文献   

10.
11.
NADP specific dihydroxyacetone reductase from Dunaliella parva   总被引:3,自引:0,他引:3  
A Ben-Amotz  M Avron 《FEBS letters》1973,29(2):153-155
  相似文献   

12.
The Japanese minnow, Pseudorasbora parva, is a multiple spawner that lays eggs repeatedly during the spawning season. In laboratory aquaria, 19 of 63 females did not spawn, whereas 44 other females laid 167 to 6285 eggs in 1 to 14 mating sequences. Neither fish density nor sex ratio (number of males per female) affected fecundity, but the increase in fish density significantly decreased the growth rate of females. The increase in male length significantly increased fecundity in aquaria which contained only a single male, whereas it decreased female growth rate. These relationships were not evident in aquaria housing three or ten males. Since larger males were more dominant and had larger testes than smaller males, the correlation between fecundity and male size strongly suggests that individual females regulated fecundity to increase their reproductive success.  相似文献   

13.
The skull of the poorly known Asia Minor lacertid lizard Parvilacerta parva is described. In comparison to other palaearctic lacertids, Parvilacerta parva displays several peculiar traits such as a large braincase, a short parietal table, closed post-temporal openings, reduced ossification, or a large lacrimal. Many features are related to the small size of Parvilacerta parva and are of apparently heterochronic nature, as they can also be found in certain ontogenetic stages of other lacertid species. Small size and heterochrony even seem to be factors involved in the less-developed sexual dimorphism of Parvilacerta parva. The described morphology is interpreted to be related to a life history strategy in r-selecting, semiarid environments.  相似文献   

14.
Cryopreservation of infective particles of Theileria parva   总被引:7,自引:0,他引:7  
Cryopreservation of infective particles of Theileria parva. International Journal for Parasitology3: 583–587. Infective particles of Theileria parva, the causative organism of East Coast fever of cattle, were obtained from infected Rhipicephalus appendiculatus ticks, either by using an in vitro feeding technique or by grinding the ticks in a suitable medium. If foetal calf serum containing 15% glycerol (v/v) was added to the infective material and it was then distributed either to glass capillary tubes (in vitro tick feed) or glass tubes (ground tick supernate) it could be slowly frozen to either ?80°C or ?196°C without loss of viability. Stabilates, tested by rapid thawing and inoculation into ECF-susceptible cattle, remained viable for up to a year at these temperatures.  相似文献   

15.
Flowers of Liparia parva from which rodents were excluded had lower seed‐set than open flowers. The rodent Acomys subspinosus was captured in the vicinity of this plant species and captures had substantial numbers of L. parva pollen in their scats. Captured individuals of A. subspinosus visited L. parva flowers in tanks and removed standard petals to obtain the nectar. Typical of rodent‐pollinated species, L. parva, flowered in winter and flowers mostly opened in the evenings and the stigma‐nectar distance was about 10 mm. This is the first evidence for rodent pollination in the large cosmopolitan family, the Fabaceae.  相似文献   

16.
To evaluate the spawning success of male Japanese minnows,Pseudorasbora parva, and female mate choice, spawning behaviour was observed under both artificial and experimental conditions. Larger males had larger territories and greater reproductive success. The body weight of territorial males decreased during the maintenance of territories, while that of non-territorial males increased significantly. When the weight of non-territorial males exceeded that of territorial males, the former began to establish new territories on the substrate, suggesting a conditional strategy by non-territorial males to trade off immediate reproductive success with growth and hence improve future reproductive success. Females chose males with larger body size, probably based on dominance rank rather than the quality (or size) of territory. It was concluded that females choose males of higher dominance rank and that males compete for large territories, both of which play an important part in male reproductive success.  相似文献   

17.
18.
Starch metabolism in Dunaliella parva Lerche is regulated by the osmolarity of the surrounding solute. Two isozymes showing amylolytic activity were obtained after purification by gel filtration chromatography. The isozymes show disproportionating activity (D‐enzyme) that is specific for malto‐oligosaccharides as substrate. Properties of the D‐enzyme in D. parva are similar to those in higher plants. The activity of the D‐enzyme is also found in various Dunaliella and Chlamydomonas, indicating that the D‐enzyme is also important in the starch metabolism in algae.  相似文献   

19.
Theileria parva genomics reveals an atypical apicomplexan genome   总被引:2,自引:0,他引:2  
The discipline of genomics is setting new paradigms in research approaches to resolving problems in human and animal health. We propose to determine the genome sequence of Theileria parva, a pathogen of cattle, using the random shotgun approach pioneered at The Institute for Genomic Research (TIGR). A number of features of the T. parva genome make it particularly suitable for this approach. The G+C content of genomic DNA is about 31%, non-coding repetitive DNA constitutes less than 1% of total DNA and a framework for the 10-12 Mbp genome is available in the form of a physical map for all four chromosomes. Minisatellite sequences are the only dispersed repetitive sequences identified so far, but they are limited in distribution to 13 of 33 SfiI fragments. Telomere and sub-telomeric non-coding sequences occupy less than 10 kbp at each chromosomal end and there are only two units encoding cytoplasmic rRNAs. Three sets of distinct multicopy sequences encoding ORFs have been identified but it is not known if these are associated with expression of parasite antigenic diversity. Protein coding genes exhibit a bias in codon usage and introns when present are unusually short. Like other apicomplexan organisms, T. parva contains two extrachromosomal DNAs, a mitochondrial DNA and a plastid DNA molecule. By annotating the genome sequence, in combination with the use of microarray technology and comparative genomics, we expect to gain significant insights into unique aspects of the biology of T. parva. We believe that the data will underpin future research to aid in the identification of targets of protective CD8+ cell mediated immune responses, and parasite molecules involved in inducing reversible host leukocyte transformation and tumour-like behaviour of transformed parasitised cells.  相似文献   

20.
To assess the spatial variability in external morphology of non-native populations of topmouth gudgeon Pseudorasbora parva within an ontogenetic context, triple regression analysis (distance-based measurements) was applied to data from eight European populations (two Slovak, four Romanian, one English and one French). The data from Slovakia were also subjected to geometrical analysis (co-ordinates-based measurements) to obtain a more complex picture of the species' overall morphology. Great phenotypic variability was observed, being expressed not only in the formation of different definite phenotypes but also in the manner by which the phenotypes are achieved. Thus, both the definite phenotype and the patterns of development in invasive P. parva may be highly influenced by environmental conditions. Such great morphological (phenotypic) variability is likely to be one of the attributes that make this species such a successful invader.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号