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21.
Maria J. Sanchez James M. Bradeen 《Molecular breeding : new strategies in plant improvement》2006,17(2):137-148
Resistance (R) genes and the proteins they encode are key components of the defense system of plants. The exploration of R
gene diversity enables the study of R gene evolution and may facilitate the isolation of new and functional alleles. Most
cloned R genes occur in clusters of related sequences. Thus, the development of a tool for reliable recovery of orthologous
R gene sequences to the exclusion of paralogous sequences will facilitate R gene diversity analysis. The late blight resistance
gene RB is a single functional locus embedded within a cluster of related sequences. Previously, the functional RB allele was cloned from wild potato using a Long Range-PCR (LR-PCR) technique, suggesting this method may be a promising tool
for recovery of R gene orthologs in other genotypes. Using the RB gene as a model, we explored the limitations and improved three technical aspects of LR-PCR for multi-genotype applications.
We present improved primers for the recovery of the RB locus and have identified efficient DNA extraction procedures and reliable amplification systems. We document that consensus
sequences built from three independently generated LR-PCR clones can be up to 100% accurate. Our results show encouraging
advances toward successful application of LR-PCR for isolating alleles from orthologous R gene loci. 相似文献
22.
ABSTRACT Molted feathers are becoming increasingly important as a source of DNA for identifying the sex of individuals, and accurate methods for molecular sex identification are needed. Three molecular sex identification primer sets have been developed for use in nearly all nonratite birds, but performance of these primer sets has not been evaluated for molted feathers. For two species of birds, the Ring‐necked Pheasant (Phasianus colchicus) and the Scarlet Macaw (Ara macao), we evaluated success and error rates among primer sets using DNA from molted feathers and assessed the percentage of times an incorrect sex would be assigned when analyses are completed in duplicate. Amplification success rates differed among the primer sets for both species, ranging from 67.5% to 89.2% (P= 0.0002 and 0.009), and error rates were high, ranging from 1.9% to 24.2%. Success rates and error rates were not consistent between species and among primer sets. To improve the accuracy of molecular sex identification tests when using molted feathers, we suggest determining acceptable confidence levels in the accuracy of sex assignment, conducting pilot tests to evaluate the performance of different primer sets, and using high‐resolution electrophoresis systems to increase detection of errors. 相似文献
23.
Dian EA Papatheodorou P Emmrich K Randel O Geissler A Kölling R Rassow J Motz C 《Journal of molecular biology》2008,377(5):1314-1323
The γ-subunit is required for the assembly of ATP synthases and plays a crucial role in their catalytic activity. We stepwise shortened the N-terminus and the C-terminus of the γ-subunit in the mitochondrial ATP synthase of yeast and investigated the relevance of these segments in the assembly of the enzyme and in the growth of the cells. We found that a deletion of 9 residues at the N-terminus or 20 residues at the C-terminus still allowed efficient import of the subunit into mitochondria; however, the assembly of both monomeric and dimeric holoenzymes was partially impaired. γ-Subunits lacking 13 N-terminal residues or 30 C-terminal residues were not assembled. Yeast strains expressing either of the truncated γ-subunits did not grow on non-fermentable carbon sources, indicating that non-assembled parts of the ATP synthase accumulated and impaired essential mitochondrial functions. 相似文献
24.
Stefan Merker Christine Driller Irene Neri-Arboleda Hans Zischler 《Conservation Genetics》2008,9(5):1349-1351
This study reports the isolation and characterization of eight microsatellite markers for the study of Philippine tarsiers
(Tarsius syrichta), small primates endemic to this Southeast Asian archipelago. The markers were used to screen 14 Tarsius syrichta for allelic diversity. This suite of highly polymorphic microsatellites provides the first chance to genetically study parentage
and dispersal patterns in Philippine tarsiers. 相似文献
25.
Haque A Rai V Bahal BS Shukla S Lattif AA Mukhopadhyay G Prasad R 《Biochemical and biophysical research communications》2007,352(2):491-497
Candida drug resistance protein (Cdr1p) is a major drug efflux protein, which plays a key role in commonly encountered clinical azole resistance in Candida albicans. We have analyzed its sequence in several azole resistant clinical isolates to evaluate the allelic variation within CDR1 gene and to relate it to its functional activity. The sequence analysis revealed 53 single nucleotide polymorphisms (SNPs), out of which six were non-synonymous single nucleotide polymorphisms (NS-SNPs) implying a change in amino acid and were found in two or more than two allelic combinations in different sensitive or resistant isolates. We have identified three new NS-SNPs namely, E948P, T950S, and F1399Y, in isolates wherein F1399Y appeared to be unique and was present in one of the naturally occurring azole resistant isolates obtained from Indian diabetic patients. However, site-directed mutagenesis showed that the residue F1399 in between TMS 11 and TMS 12 does not affect the functionality of Cdr1p. Taken together, our SNPs analyses reveal that unlike human P-gp, the naturally acquired allelic variations are mostly present in non-conserved regions of the protein which do not allow Cdr1p to genetically evolve in a manner, that would allow a change in its functionality to affect substrate recognition, specificity, and drug efflux activity of C. albicans cells. 相似文献
26.
Struebig MJ Kingston T Petit EJ Le Comber SC Zubaid A Mohd-Adnan A Rossiter SJ 《Ecology letters》2011,14(6):582-590
The potential for parallel impacts of habitat change on multiple biodiversity levels has important conservation implications. We report on the first empirical test of the 'species-genetic diversity correlation' across co-distributed taxa with contrasting ecological traits in the context of habitat fragmentation. In a rainforest landscape undergoing conversion to oil palm, we show that depauperate species richness in fragments is mirrored by concomitant declines in population genetic diversity in the taxon predicted to be most susceptible to fragmentation. This association, not seen in the other species, relates to fragment area rather than isolation. While highlighting the over-simplification of extrapolating across taxa, we show that fragmentation presents a double jeopardy for some species. For these, conserving genetic diversity at levels of pristine forest could require sites 15-fold larger than those needed to safeguard species numbers. Importantly, however, each fragment contributes to regional species richness, with larger ones tending to contain more species. 相似文献
27.
In the African clawed frog (Xenopus laevis), two deeply divergent allelic lineages of multiple genes of the class I MHC region have been discovered. For the MHC class I UAA locus, functional differences and the molecular basis for lineages maintenance are unknown. Alleles of linked class I region genes also exhibit strong disequilibrium with specific MHC alleles, but the underlying cause is not clear. We use MHC class Ia sequence data to estimate substitution rates and investigate structural differences between allelic lineages from protein models. Results indicate the operation of natural selection, and differences in the steric properties in the F pocket of the peptide-binding region among lineages. Variability in this pocket likely enables allelic lineages to bind very different sets of peptides and to interact differently with MHC chaperones in the endoplasmic reticulum. These results constitute evidence of the molecular evolutionary basis for 1) the maintenance of allelic lineages, 2) functional differences among lineages, and 3) strong linkage disequilibrium of allelic variants of class I region genes in X. laevis.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
28.
29.
Microsatellites and microsynteny in the chloroplast genomes of Oryza and eight other Gramineae species 总被引:9,自引:0,他引:9
T. Ishii S. R. McCouch 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(8):1257-1266
Primer pairs flanking ten chloroplast microsatellite loci, originally identified in Oryza
sativa cv Nipponbare, were evaluated for amplification and allelic diversity using a panel of 13 diverse cultivars of rice (O. sativa), 19 accessions of wild rice (three O. officinalis, five O. latifolia, five O.
minuta, four O. australiensis, one O. brachyantha and one O. ridleyi) and eight other Gramineae species (maize, teosinte, wheat, oat, barley, pearl millet, sorghum and sugarcane). Amplified
products were obtained for all samples at nine out of ten loci. Among the rice cultivars, the number of alleles per locus
ranged from one to four, with monomorphic patterns observed at five loci. The average polymorphism information content (PIC)
value at the other five (polymorphic) loci was 0.54 among the 13 cultivars. When wild rice and the other Gramineae species
were compared based on the proportion of shared alleles, their phylogenetic relationships were in agreement with previous
studies using different types of markers; however, the magnitude of the differences based on chloroplast microsatellites underestimated
the genetic distance separating these divergent species and genera. A sequence-based comparison of homologous regions of the
rice and maize chloroplast genomes revealed that, while a high level of microsynteny is evident, the occurrence of actively
evolving microsatellite motifs in specific regions of the rice chloroplast genome appears to be mainly a species or genome-specific
phenomenon. Thus the chloroplast primer pairs used in this study bracketed mutationally active microsatellite motifs in rice
but degenerate, interrupted motifs or highly conserved, mutationally inert motifs in distantly related genera.
Received: 17 March 1999 / Accepted: 11 November 1999 相似文献
30.