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1.
M. P. De Leon T. Yanagi M. Kikuchi J. Mu O. Ayau V. Matta M. Paz S. Juarez H. Kanbara I. Tada K. Hirayama 《International journal for parasitology》1998,28(12):1867-1874
Fifty fresh isolates of Trypanosoma cruzi from Triatoma dimidiata vectors and 31 from patients with Chagas disease were analysed for DNA polymorphisms within the 432-bp core region of the cruzipain gene which encodes the active site of cathepsin L-like cystein proteinase. The cruzipain gene showed signs of polymorphism consisting of four different DNA sequences in Central and South American isolates of T. cruzi. The PCR fragments of Guatemalan isolates could be divided into three groups, Groups 1, 2 and 3, based on different patterns of single-stranded DNA conformation polymorphism. All of the strains isolated from Brazil, Chile, and Paraguay, except for the CL strain, showed a Group 4 pattern. Two to four isolates from each group were analysed by cloning and sequencing. A silent mutation occurred between Groups 1 and 2, and five nucleotides and two aa substitutions were detected between Groups 1 and 3. The DNA sequence of Group 4 contained five nucleotides and one aa substitution from Group 1. All of the DNA sequences corresponded well with the single-stranded DNA conformation polymorphism. The Group 1 isolates, the majority in the Guatemalan population (70/81, 86.4%), were isolated from both triatomines and humans, but Group 3 were isolated only from humans. Moreover, the Group 2 isolates were detected only in triatomine vectors (9/50; 18%), but never in humans (0/32, P<0.05) suggesting that this group has an independent life-cycle in sylvatic animals and is maintained by reservoir hosts other than humans. 相似文献
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Tanaka Osamu; Nasu Yutaka; Sonoyama Akiko; Maehara Yasuko; Kobayashi Takako; Nawafune Hidemi; Kugimoto Mamoru 《Plant & cell physiology》1987,28(4):697-702
The flowering of Lemna paucicostata 6746 grown on 14-h photoperiodwas enhanced by the addition of high concentrations of ironto the medium, which also increased the endogenous iron concentration.The addition of asparagine, aspartate, glutamate, -alanine,glycine or serine to the medium also increased the endogenousiron level, resulting in the promotion of flowering. In contrast,the addition of cysteine, cystine, glutamine, arginine, threonineor phenylalanine lowered the endogenous iron level, resultingin the inhibition of flowering. Glycine and asparagine added to the medium during an inductive96-h dark period did not promote iron uptake and had no effecton flowering, but when added during the subsequent 120-h lightperiod, they promoted both iron uptake and flowering response.The increase in the endogenous iron level seems to favor floraldevelopment rather than induction of photoperiodic floweringof Lemna paucicostata 6746. (Received September 8, 1986; Accepted March 31, 1987) 相似文献
5.
In order to elucidate the evolution of C4 syndrome, the taxonomic relationships, leaf anatomy, and ecological and global distribution of C3 and C4 species in the genusRhynchospora were investigated. The anatomical observation for 181 species revealed that 26 C4 species occurred within theCapitatae group of the subgenusHaplostyleae, a natural group showing highly advanced morphological characteristics, together with several C3 species. In spite of there being rather few C4 species, they possessed two kinds of Kranz anatomical structure differing from each other in the location of Kranz cells. Some C3 species ofCapitatae showed radial arrangement in mesophyll cells surrounding vascular bundles, which is distinguished from typical non-Kranz anatomy. The C4 species extended their ecological ranges from wet habitats to dry savanna grasslands, while the C3 species showed the best development in wet habitats. The C3 species were widespread from tropical to temperate regions with partial range extension into subarctic regions of both hemispheres, showing conspicuously high concentration of species in the New World, but being absent from arid climatic regions. The C4 species were distributed mostly in tropics and subtropics, showing two separate distributional centers in South and Central America and in Tropical Asia and Australia. The range of C4 species was nearly completely included in the C3 range. In conclusion, it seems that inRhynchospora the C4 syndrome evolved relatively recently, and arose in at least two separate phylogenetic trends in the tropics and the subtropics, more probably in the Neotropics. 相似文献
6.
The nitro- and amino-substituted phenazines were synthesized and assayed for their mutagenicity in Salmonella typhimurium strains TA98 and TA98NR. Of 7 tested nitrophenazines, 4 were mutagenic in the absence of a microsomal metabolic activation system (S9 mix) and were more mutagenic in TA98 than in TA98NR. The order of mutagenicity of nitrophenazines in TA98 is 1.7- less than 2- less than 2.8- less than 2.7-substituted phenazine. Of 7 tested amino derivatives, 4 exhibited mutagenic activity with S9 mix in TA98. 1-Nitro-, 1-amino, 1.6-dinitro-, 1.9-dinitro-, 1.6-diamino- and 1.9-diamino-phenazine were not mutagenic. As regards the relationship between mutagenic potency and chemical structure of the phenazines, the results suggested that structural requirements favoring mutagenic activity were the presence of substituents at the 2 and/or 7 position. Furthermore, 2.7-disubstituted phenazines were extremely mutagenic, 2.7-dinitrophenazine and 2.7-diaminophenazine induced 36,450 and 12,110 rev./nmole, respectively. In the preliminary study, 2.7-diaminophenazine was identified by gas chromatography/mass spectrometry from the reaction mixture of m-phenylenediamine and hydrogen peroxide. 相似文献
7.
Hiroshi Ishii Osamu Nadaoka Yoshimasa Mimura Yoshio Inoue Riichir Chûj 《International journal of biological macromolecules》1989,11(6)
A tetrapetide containing an Aib residue, Boc-Asn-Aib-Thr-Aib-OMe, was synthesized as a peptide model for the N-glycosylation site in N-glycoproteins. Backbone conformation of the peptide and possible intramolecular interaction between the Asn and Thr side chains were elucidated by means of n.m.r. spectroscopy. Temperature dependence of NH proton chemical shift and NOE experiments showed that Boc-Asn-Aib-Thr-Aib-OMe has a tendency to form a β-turn structure with a hydrogen bond involving Thr and Aib4 NH groups. Incorporation of Aib residues in the peptide model promotes folding of the peptide backbone. With folded backbone conformation, carboxyamide protons of the Asn residue are not involved in hydrogen bond network, while the OH group of the Thr residue is a candidate for a hydrogen bond in DMSO-d6 solution. 相似文献
8.
Osamu Kondo Hiroyuki Honda Masahito Taya Takeshi Kobayashi 《Applied microbiology and biotechnology》1989,32(3):291-294
Summary Growth properties of carrot hairy root cells in various bioreactors were investigated. A turbine-blade reactor and an immobilized rotating drum reactor were found to be advantageous for the hairy root culture because of a high oxygen transfer coefficient (k in L a). After 30 days of culture, 10 g/l of dry hairy root cells were obtained in both bioreactors and maximum growth rates (V
m
) were found to be 0.63 and 0.61 g/l per day for the turbine-blade reactor and immobilized rotating drum reactor, respectively. Specific growth rates () at various cultivation times were observed to be linearly proportional to X/k
l
a for both bioreactor configurations where X is the cell concentration. The estimated specific oxygen uptake rate of 0.34 mmol O2/g dry cells per hour compares fairly well with an experimental value of 0.3. 相似文献
9.
S Akashi K Hirayama A Murai M Arai S Murao 《Biochemical and biophysical research communications》1989,158(2):514-519
This study indicates one of the advantages of tandem mass spectrometry; the primary structures of proteins with little structural difference can be determined by using tandem mass spectrometry without prior purification of each component. The primary structure of Paim II, a protein alpha-amylase inhibitor from Streptomyces coruchorushii, was determined by using tandem mass spectrometry. Paim II consists of two component proteins with ragged N-terminus, and was sequenced on the basis of the structure of Paim I, an analogous alpha-amylase inhibitor from the same natural origin. 相似文献
10.
M Furuya S Akashi K Hirayama 《Biochemical and biophysical research communications》1989,163(2):1100-1106
The primary structure of human epidermal growth factor (hEGF), which was produced by Escherichia coli using recombinant DNA technique, has been studied by tandem mass spectrometry. The molecular weight of hEGF (about 6200 amu) was determined by fast atom bombardment mass spectrometry. Then reduced and carboxymethylated hEGF was digested by chymotrypsin into seven peptides which could cover the whole sequence of hEGF. The amino acid sequences of five of these seven peptides could be confirmed by tandem mass spectrometry with or without isolation by high-performance liquid chromatography (HPLC). After isolation by HPLC, the other two peptides were digested with trypsin or thermolysin into small peptides, and sequenced by tandem mass spectrometry. 相似文献