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1.
The role of duplication in the expression of a variable surface glycoprotein gene of Trypanosoma brucei 总被引:1,自引:0,他引:1
The variable surface glycoprotein (VSG) genes of Trypanosoma brucei have been classified into two groups depending upon whether or not duplication of the genes is observed when they are expressed. We report here the observation of duplication apparently linked to expression of the ILTaT 1.3 gene in the ETaR 1 trypanosome stock. In the ILTaR 1 stock, expression of the ILTaT 1.3 VSG did not involve a new duplication, but instead activation of a preexisting gene copy that had been apparently generated earlier by a duplication event analogous to that directly observed in the ETaR 1 trypanosomes. The results suggest that the well-characterised gene duplications found with other VSG genes are common to all VSG genes but are not directly responsible for controlling expression. All currently available data can be accommodated by a model that assumes that gene duplication and replacement occurs independently of antigenic switching. 相似文献
2.
Junzou Hiratsuka Hiroaki Shimada Robert Whittier Takashi Ishibashi Masahiro Sakamoto Masao Mori Chihiro Kondo Yasuko Honji Chong-Rong Sun Bing-Yuan Meng Yu-Qing Li Akira Kanno Yoko Nishizawa Atsushi Hirai Kazuo Shinozaki Masahiro Sugiura 《Molecular & general genetics : MGG》1989,217(2-3):185-194
Summary The entire chloroplast genome of the monocot rice (Oryza sativa) has been sequenced and comprises 134525 bp. Predicted genes have been identified along with open reading frames (ORFs) conserved
between rice and the previously sequenced chloroplast genomes, a dicot, tobacco (Nicotiana tabacum), and a liverwort (Marchantia polymorpha). The same complement of 30 tRNA and 4 rRNA genes has been conserved between rice and tobacco. Most ORFs extensively conserved
betweenN. tabacum andM. polymorpha are also conserved intact in rice. However, several such ORFs are entirely absent in rice, or present only in severely truncated
form. Structural changes are also apparent in the genome relative to tobacco. The inverted repeats, characteristic of chloroplast
genome structure, have expanded outward to include several genes present only once per genome in tobacco and liverwort and
the large single copy region has undergone a series of inversions which predate the divergence of the cereals. A chimeric
tRNA pseudogene overlaps an apparent endpoint of the largest inversion, and a model invoking illegitimate recombination between
tRNA genes is proposed which accounts simultaneously for the origin of this pseudogene, the large inversion and the creation
of repeated sequences near the inversion endpoints. 相似文献
3.
4.
B. Bowien U. Windhövel J.-G. Yoo R. Bednarski B. Kusian 《FEMS microbiology letters》1990,87(3-4):445-450
5.
G. J. Scoles B. S. Gill Z. -Y. Xin B. C. Clarke C. L. McIntyre C. Chapman R. Appels 《Plant Systematics and Evolution》1988,160(1-2):105-122
The 5 S DNA units from 15 grasses in theTriticeae were analysed at the DNA sequence level. Four units carried duplications near the 3-end of the 5 S RNA gene with 3 of the duplications centred on the same base pairs as a duplication previously reported byGerlach & Dyer. The fourth duplication was located 3 downstream from the gene, in the spacer region. Apparent deletions were very frequent when units of the different grasses were compared and it was clear that these deletions did not extend into a 75 bp spacer region upstream from the 5 S RNA gene. This 75 bp region also tended to be more conserved between the grasses as compared to the high level of sequence change in the rest of the spacer region. — Phenetic relationships were established between the grasses using the sequence data. The relationships were generally consistent with the data from other parameters and, in addition, showed that two Australian grasses were closely related to the other Northern hemisphere genera examined. The data concerning the Australian grasses is discussed in relation to the isolated nature of Australia. 相似文献
6.
Limited Tryptic Proteolysis of the Benzodiazepine Binding Proteins in Different Species Reveals Structural Homologies 总被引:2,自引:2,他引:0
Waltraut Friedl Klaus-Ulrich Lentes Elke Schmitz Peter Propping Johannes Hebebrand 《Journal of neurochemistry》1988,51(6):1877-1881
Peptide mapping can be used to elucidate further the structural similarities of the benzodiazepine binding proteins in different vertebrate species. Crude synaptic membrane preparations were photoaffinity-labeled with [3H]flunitrazepam and subsequently degraded with various concentrations of trypsin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by fluorography allowed a comparison of the molecular weights of photolabeled peptides in different species. Tryptic degradation led to a common peptide of 40K in all species investigated, a finding indicating that the benzodiazepine binding proteins are structurally homologous in higher bony fishes and tetrapods. 相似文献
7.
8.
The electrophoretic patterns of the enzyme alcohol dehydrogenase (ADH) from Anastrepha fraterculus and A. obliqua were studied. Two loci were found to code for the enzyme in A. fraterculus, and three in A. obliqua. In both species, all isozymes were active in third-instar larvae. A cationic isozyme (Adh-1) was active mainly in the visceral fat body of both species. In A. fraterculus, the locus had an anionic polymorphic isozyme (Adh-3) that was detected in the parietal fat body. In addition to these two loci, a third locus for an anionic isozyme (Adh-2), which was active in the digestive tube of larvae, was present in A. obliqua and probably resulted from gene duplication. For both species, multiple forms of the isozymes are formed by binding of an NAD-carbonyl compound, as in Drosophila melanogaster. Both larvae and early pupae of A. obliqua had almost twice the specific ADH activity as A. fraterculus. The ethanol content of the host fruit infested with A. obliqua (red mombim) was also higher than that of the host fruit infested with A. fraterculus (guava).This research was supported by grants from Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq-PIG 40.2486/82). 相似文献
9.
Molecular characterization and genetic mapping of two clusters of genes encoding chlorophyll a/b-binding proteins in Lycopersicon esculentum (tomato) 总被引:20,自引:0,他引:20
Eran Pichersky Robert Bernatzky Steven D. Tanksley R.Bill Breidenbach Albert P. Kausch Anthony R. Cashmore 《Gene》1985,40(2-3):247-258
We have constructed a tomato genomic library in the λ Charon 4 phage vector. The library was screened with a pea cDNA probe encoding a chlorophyll a/b-binding protein (CAB), and several recombinant phages containing tomato CAB genes were isolated and characterized by restriction mapping, heteroduplex analysis and nucleotide sequencing. Two phages with overlapping segments of the tomato genome contain a total of four CAB genes, all arranged in tandem. A third phage contains three CAB genes, two arranged in tandem and one in opposite orientation, and an additional, truncated CAB gene. Genetic mapping experiments showed that the four CAB genes on the first two phages belong to a locus, previously designated Cab-1, on chromosome 2. The CAB genes from the third phage belong to the Cab-3 locus on chromosome 3. Complete sequence determination of two CAB genes, one from each locus, and additional sequence determination of about 50% of each of the other five CAB genes showed that each gene within a CAB locus is more similar to other CAB genes in the same locus than it is to the CAB genes from the second locus. Furthermore, the polypeptides encoded by Cab-1 genes diverge significantly from those encoded by Cab-3 genes in the domains of transit peptide and the N terminus of the mature polypeptide but are essentially identical in the rest of the sequence. 相似文献
10.