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1.
Normal (nonglutinous) rice plants (Oryza sativa andO. glaberrima) contain more than 18% amylose in endosperm starch, whilewaxy (glutinous) plants lack it in this starch. In contrast, leaf starch contained more than 3.6% amylose even inwaxy plants. SDS-PAGE analysis of proteins bound to endosperm starch granules in the normal plants revealed a single band with aMr of 60 kd, whereaswaxy plants did not exhibit a similar band. The activity of starch synthase (NDP-glucose-starch glucosyltransferase) was completely inhibited by antibody against the 60-kd protein. Thus, we conclude that the 60-kd protein is thewaxy protein encoded by theWx allele, which also plays a role in the synthesis of nonglutinous starch in endosperm tissue. In leaf blades, the proteins bound to starch granules separated into five bands withMr's of 53.6 to 64.9 kd on SDS-PAGE. Analysis of these proteins by immunoblotting using antiserum againstWx protein and inhibition of starch synthase activity by the synthase antibody revealed that none of these proteins was homologous toWx protein. We suggest that the synthesis of amylose in leaf blades is brought about by a protein encoded by a gene(s) different from theWx gene expressed in the endosperm. 相似文献
2.
Mapping quantitative trait loci underlying the cooking and eating quality of rice using a DH population 总被引:7,自引:1,他引:6
The cooking and eating quality of rice has attracted more attention recently. In a comprehensive effort to unravel its genetic basis, we conducted a genome-wide analysis of six traits representing the cooking and eating quality of rice grain, namely, amylose content (AC), gel consistency (GC), gelatinization temperature (GT), water absorption (WA), cooked rice elongation (CRE) and volume expansion (VE) using a DH population derived from the anther culture of an F1 hybrid between WYJ 2 (japonica) and Zhenshan 97B (indica). For each trait, one to three quantitative trait loci (QTL) were found, which were located on chromosomes 1, 2, 3, 6, 11. QTL analysis revealed a major QTL specifying GT, located at the interval RM276-RM121, which should be the same locus as the alkali degeneration gene (alk), while for each of the remaining five traits the QTL explaining the largest proportion of variance was located on the short arm of chromosome 6, centered at RM190 (found in the waxy gene). Our results, in combination with previous reports, further confirmed that either the waxy gene itself or a genomic region tightly linked to it plays a major role in determining the cooking and eating quality of rice. 相似文献
3.
Shiaoman Chao Wenjun Zhang Eduard Akhunov Jamie Sherman Yaqin Ma Ming-Cheng Luo Jorge Dubcovsky 《Molecular breeding : new strategies in plant improvement》2009,23(1):23-33
In this study, we developed 359 detection primers for single nucleotide polymorphisms (SNPs) previously discovered within
intron sequences of wheat genes and used them to evaluate SNP polymorphism in common wheat (Triticum aestivum L.). These SNPs showed an average polymorphism information content (PIC) of 0.18 among 20 US elite wheat cultivars, representing
seven market classes. This value increased to 0.23 when SNPs were pre-selected for polymorphisms among a diverse set of 13
hexaploid wheat accessions (excluding synthetic wheats) used in the wheat SNP discovery project (). PIC values for SNP markers in the D genome were approximately half of those for the A and B genomes. D genome SNPs also
showed a larger PIC reduction relative to the other genomes (P < 0.05) when US cultivars were compared with the more diverse set of 13 wheat accessions. Within those accessions, D genome
SNPs show a higher proportion of alleles with low minor allele frequencies (<0.125) than found in the other two genomes. These
data suggest that the reduction of PIC values in the D genome was caused by differential loss of low frequency alleles during
the population size bottleneck that accompanied the development of modern commercial cultivars. Additional SNP discovery efforts
targeted to the D genome in elite wheat germplasm will likely be required to offset the lower diversity of this genome. With
increasing SNP discovery projects and the development of high-throughput SNP assay technologies, it is anticipated that SNP
markers will play an increasingly important role in wheat genetics and breeding applications.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
5.
Emily R. A. Cramer L. Stenzler A. L. Talaba C. A. Makarewich S. L. Vehrencamp I. J. Lovette 《Conservation Genetics》2008,9(6):1657-1660
Single nucleotide polymorphisms (SNPs) are becoming more commonly used as molecular markers in conservation studies. However,
relatively few studies have employed SNPs for species with little or no existing sequence data, partly due to the practical
challenge of locating appropriate SNP loci in these species. Here we describe an application of SNP discovery via shotgun
cloning that requires no pre-existing sequence data and is readily applied to all taxa. Using this method, we isolated, cloned
and screened for SNP variation at 90 anonymous sequence loci (51 kb total) from the banded wren (Thryothorus pleurostictus), a Central American species with minimal pre-existing sequence data and a documented paucity of microsatellite allelic variation.
We identified 168 SNPs (a mean of one SNP/305 bp, with SNPs unevenly distributed across loci). Further characterization of
variation at 41 of these SNP loci among 256 individuals including 37 parent–offspring families suggests that they provide
substantial information for defining the genetic mating system of this species, and that SNPs may be generally useful for
this purpose when other markers are problematic. 相似文献
6.
Discovery of a new fragrance allele and the development of functional markers for the breeding of fragrant rice varieties 总被引:3,自引:0,他引:3
Weiwei Shi Yi Yang Saihua Chen Mingliang Xu 《Molecular breeding : new strategies in plant improvement》2008,22(2):185-192
The recessive fgr gene on chromosome 8 is associated with rice fragrance. It has been reported that this gene is a non-functional badh2 allele and that the functional Badh2 allele encoding putative betaine aldehyde dehydrogenase (BADH2) could render rice non-fragrant. Here we report the discovery
of a new badh2 allele and the development of functional markers for the badh2 locus. A total of 24 fragrant and ten non-fragrant rice varieties were studied and sequenced for their Badh2/badh2 loci. Of the 24 fragrant rice varieties, 12 were found to have the known badh2 allele (badh2-E7), which has an 8-bp deletion and three single nucleotide polymorphisms (SNPs) in exon 7; the others had a novel null badh2 allele (badh2-E2), which has a sequence identical to that of the Badh2 allele in exon 7, but with a 7-bp deletion in exon 2. Both null badh2 alleles are responsible for rice fragrance. Based on sequence divergence amongst the functional Badh2 and two null badh2 alleles, we developed functional markers which can be easily used to distinguish non-fragrant from fragrant rice and to differentiate
between two kinds of fragrant rice. These functional markers will find their usefulness in breeding for fragrant rice varieties
via marker-assisted selection.
Weiwei Shi and Yi Yang contributed equally to this work. 相似文献
7.
Bradley J. Till Joanna Jankowicz-Cieslak László Sági Owen A. Huynh Hiroe Utsushi Rony Swennen Ryohei Terauchi Chikelu Mba 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,121(7):1381-1389
Musa (banana and plantain) is an important genus for the global export market and in local markets where it provides staple food
for approximately 400 million people. Hybridization and polyploidization of several (sub)species, combined with vegetative
propagation and human selection have produced a complex genetic history. We describe the application of the Ecotilling method
for the discovery and characterization of nucleotide polymorphisms in diploid and polyploid accessions of Musa. We discovered over 800 novel alleles in 80 accessions. Sequencing and band evaluation shows Ecotilling to be a robust and
accurate platform for the discovery of polymorphisms in homologous and homeologous gene targets. In the process of validating
the method, we identified two single nucleotide polymorphisms that may be deleterious for the function of a gene putatively
important for phototropism. Evaluation of heterozygous polymorphism and haplotype blocks revealed a high level of nucleotide
diversity in Musa accessions. We further applied a strategy for the simultaneous discovery of heterozygous and homozygous polymorphisms in
diploid accessions to rapidly evaluate nucleotide diversity in accessions of the same genome type. This strategy can be used
to develop hypotheses for inheritance patterns of nucleotide polymorphisms within and between genome types. We conclude that
Ecotilling is suitable for diversity studies in Musa, that it can be considered for functional genomics studies and as tool in selecting germplasm for traditional and mutation
breeding approaches. 相似文献
8.
Nwakanma DC Pillay M Okoli BE Tenkouano A 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,108(1):154-159
Musa acuminata Colla (AA genomes) and Musa balbisiana Colla (BB genomes) are the diploid ancestors of modern bananas that are mostly diploid or triploid cultivars with various combinations of the A and B genomes, including AA, AAA, BB, AAB and ABB. The objective of this study was to identify molecular markers that will facilitate discrimination of the A and B genomes, based on restriction-site variations in the internal transcribed spacers (ITS) of the nuclear ribosomal RNA genes. The ITS regions of seven M. acuminata and five M. balbisiana accessions were each amplified by PCR using specific primers. All accessions produced a 700-bp fragment that is equivalent in size to the ITS of most plants. This fragment was then digested with ten restriction enzymes (AluI, CfoI, DdeI, HaeIII, HinfI, HpaII, MspI, RsaI, Sau3AI and TaqI) and fractionated in 2% agarose gels, stained with ethidium bromide and visualized under UV light. The RsaI digest revealed a single 530-bp fragment unique to the A genome and two fragments of 350-bp and 180-bp that were specific to the B genome. A further 56 accessions representing AA, AAA, AAB, AB and ABB cultivars, and synthetic hybrids, were amplified and screened with RsaI. All accessions with an exclusively A genome showed only the 530-bp fragment, while accessions having only the B-genome lacked the 530-bp fragment but had the 350-bp and 180-bp fragments. Interspecific cultivars possessed all three fragments. The staining intensity of the B-genome markers increased with the number of B-genome complements. These markers can be used to determine the genome constitution of Musa accessions and hybrids at the nursery stage, and, therefore, greatly facilitate genome classification in Musa breeding.Communicated by H.F. Linskens 相似文献
9.
Development of PCR-based SNP markers for rice blast resistance genes at the<Emphasis Type="Italic"> Piz</Emphasis> locus 总被引:16,自引:0,他引:16
Hayashi K Hashimoto N Daigen M Ashikawa I 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,108(7):1212-1220
We assessed the utility of single-nucleotide polymorphisms (SNPs) and small insertion/deletion polymorphisms (InDels) as DNA markers in genetic analysis and breeding of rice. Toward this end, we surveyed SNPs and InDels in the chromosomal region containing the Piz and Piz-t rice blast resistance genes and developed PCR-based markers for typing the SNPs. Analysis of sequences from a blast-susceptible Japanese cultivar and two cultivars each containing one of these genes revealed that SNPs are abundant in the Piz and Piz-t regions (on average, one SNP every 248 bp), but the number of InDels was much lower. The dense distribution of SNPs facilitated the generation of SNP markers in the vicinity of the genes. For typing these SNPs, we used a modified allele-specific PCR method. Of the 49 candidate allele-specific markers, 33 unambiguously and reproducibly discriminated between the two alleles. We used the markers for mapping the Piz and Piz-t genes and evaluating the size of DNA segments introgressed from the Piz donor cultivar in Japanese near-isogenic lines containing Piz. Our findings suggest that, because of its ability to generate numerous markers within a target region and its simplicity in assaying genotypes, SNP genotyping with allele-specific PCR is a valuable tool for gene mapping, map-based cloning, and marker-assisted selection in crops, especially rice.Communicated by D.J. Mackill 相似文献
10.
Development and mapping of SNP assays in allotetraploid cotton 总被引:1,自引:0,他引:1
Byers RL Harker DB Yourstone SM Maughan PJ Udall JA 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2012,124(7):1201-1214
A narrow germplasm base and a complex allotetraploid genome have made the discovery of single nucleotide polymorphism (SNP)
markers difficult in cotton (Gossypium
hirsutum). To generate sequence for SNP discovery, we conducted a genome reduction experiment (EcoRI, BafI double digest, followed by adapter ligation, biotin–streptavidin purification, and agarose gel separation) on two accessions
of G. hirsutum and two accessions of G. barbadense. From the genome reduction experiment, a total of 2.04 million genomic sequence reads were assembled into contigs with an
N50 of 508 bp and analyzed for SNPs. A previously generated assembly of expressed sequence tags (ESTs) provided an additional
source for SNP discovery. Using highly conservative parameters (minimum coverage of 8× at each SNP and 20% minor allele frequency),
a total of 11,834 and 1,679 non-genic SNPs were identified between accessions of G. hirsutum and G. barbadense in genome reduction assemblies, respectively. An additional 4,327 genic SNPs were also identified between accessions of G. hirsutum in the EST assembly. KBioscience KASPar assays were designed for a portion of the intra-specific G. hirsutum SNPs. From 704 non-genic and 348 genic markers developed, a total of 367 (267 non-genic, 100 genic) mapped in a segregating
F2 population (Acala Maxxa × TX2094) using the Fluidigm EP1 system. A G. hirsutum genetic linkage map of 1,688 cM was constructed based entirely on these new SNP markers. Of the genic-based SNPs, we were
able to identify within which genome (‘A’ or ‘D’) each SNP resided using diploid species sequence data. Genetic maps generated
by these newly identified markers are being used to locate quantitative, economically important regions within the cotton
genome. 相似文献
11.
Dreb1 genes in wheat (Triticum aestivum L.): development of functional markers and gene mapping based on SNPs 总被引:1,自引:0,他引:1
Bo Wei Ruilian Jing Chengshe Wang Jibao Chen Xinguo Mao Xiaoping Chang Jizeng Jia 《Molecular breeding : new strategies in plant improvement》2009,23(1):13-22
The Dreb genes are involved in abiotic stress tolerances, such as drought, salinity, low temperature and ABA. The purpose of the present
research was to establish protocols for the development of genome-specific and allele specific markers in common wheat (Triticum aestivum L.) using the Dreb1 genes as an example. Based on the available sequences of Dreb1 genes in common wheat and related species, five primer pairs were designed using Primer Premier 5.0. Two primers, P25F/PR
and P21F/P21R, amplified 596- and 1113-bp fragments, respectively, from the A genome, P18F/P18R amplified a 717-bp fragment
from the B genome, and primers P22F/PR and P20F/P20R amplified 596- and 1193-bp fragments, respectively, from the D genome.
Using these genome-specific primers and the Chinese Spring using nulli-tetrasomic lines, the Dreb1 genes were located on chromosomes 3A, 3B and 3D. Two SNPs (S646 and S770) in Dreb-B1 distinguished the Opata 85 and W7984 parents of the ITMI mapping population, but there was no polymorphism between the orthologous
Dreb-A1 and Dreb-D1 sequences. By assaying the genotypes of 115 RILs with the allele-specific primer P40 based on SNP S770, Dreb-B1 was mapped between markers Xmwg818 and Xfbb117 on chromosome 3BL. This genetic mapping of Dreb-B1 on chromosome 3B may be helpful in wheat breeding programs aimed at improving drought tolerance. 相似文献
12.
T. P. Tourova T. N. Nazina E. M. Mikhailova T. A. Rodionova A. N. Ekimov A. V. Mashukova A. B. Poltaraus 《Molecular Biology》2008,42(2):217-226
Screening for alkane hydroxylase genes (alkB) was performed in thermophilic aerobic bacteria of the genus Geobacillus. Total DNAs were isolated from the biomass of 11 strains grown on a mixture of saturated C10–C20 hydrocarbons. Fragments of alkB genes were amplified by PCR with degenerate oligonucleotide primers, and the PCR products were cloned and sequenced. For the first time, a set of alkB gene homologs was detected in the genomes of thermophilic bacteria. The strains each contained three to six homologs, of which only two were common for all of the strains. Phylogenetic analysis of the nucleotide sequences and the deduced amino acid sequences showed that six of the variants revealed in Geobacillus were closely related to alkB4, alkB3, and alkB2, found in Rhodococcus erythropolis strains NRRL B-16531 and Q15. All variants of alkB sequences were unique. Analysis of the GC composition showed that the Geobacillus alkB homologs are closer to Rhodococcus than to Geobacillus chromosomal DNA. It was assumed that the alkB genes were introduced in the Geobacillus genome via interspecific horizontal transfer and that Rhodococcus or other representatives of Actinobacteria served as donors. Analysis of the codon usage in the fragments of alkB genes confirmed the suggestion that the pool of these genes is common to the majority of Gram-positive and certain Gram-negative bacteria. The formation of a set of several alkB homologs in a genome of a particular microorganism may result from free gene exchange within this pool. 相似文献
13.
S. S. Figdore W. C. Kennard K. M. Song M. K. Slocum T. C. Osborn 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,75(6):833-840
Summary The feasibility of creating a restriction fragment length polymorphism (RFLP) linkage map in Brassica species was assessed by screening EcoRI-, HindIII-, or EcoRV-digested total genomic DNA from several accessions of B. campestris, B. oleracea, and B. napus using random genomic DNA clones from three Brassica libraries as hybridization probes. Differences in restriction fragment hybridization patterns occurred at frequencies of 95% for comparisons of accessions among species, 79% for comparisons of accessions among subspecies within species, and 70% for comparisons among accessions within subspecies. In addition, species differences in the level of hybridization were noted for some clones. The high degree of polymorphism found even among closely related Brassica accessions indicates that RFLP analysis will be a very useful tool in genetic, taxonomic, and evolutionary studies of the Brassica genus. Development of RFLP linkage maps is now in progress. 相似文献
14.
Bao JS Corke H Sun M 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2006,113(7):1171-1183
The characteristics of starch, such as gelatinization temperature (GT), apparent amylose content (AAC), pasting temperature (PT) and other physicochemical properties, determine the quality of various products of rice, e.g., eating, cooking and processing qualities. The GT of rice flour is controlled by the alk locus, which has been co-mapped to the starch synthase IIa (SSIIa) locus. In this study, we sequenced a 2,051 bp DNA fragment spanning part of intron 6, exon 7, intron 7, exon 8 and part of 3′ untranslated region of SSIIa for 30 rice varieties with diverse geographical distribution and variation in starch physicochemical properties. A total of 24 single nucleotide polymorphisms (SNPs) and one insertion/deletion (InDel) were identified, which could be classified into nine haplotypes. The mean pairwise nucleotide diversity π was 0.00292, and Watterson’s estimator θ was 0.00296 in this collection of rice germplasm. Tajima’s D test for selection showed no significant deviation from the neutral expectation (D = − 0.04612, P > 0.10). However, significant associations were found between seven of the SNPs and peak GT (T
p) at P < 0.05, of which two contiguous SNPs (GC/TT) showed a very strong association with T
p (P < 0.0001). With some rare exception, this GC/TT polymorphism alone can differentiate rice varieties with high or intermediate GT (possessing the GC allele) from those with low GT (possessing the TT allele). In contrast, none of these SNPs or InDel was significantly associated with amylose content. A further 509 rice varieties with known physicochemical properties (e.g., AAC and PT) and known alleles of other starch synthesizing genes were genotyped for the SSIIa GC/TT alleles. Association analysis indicated that 82% of the total variation of AAC in these samples could be explained by a (CT)n simple sequence repeat (SSR) and a G/T SNP of Waxy gene (Wx), and 62.4% of the total variation of PT could be explained by the GC/TT polymorphism. An additional association analysis was performed between these molecular markers and the thermal and retrogradation properties for a subset of 245 samples from the 509 rice varieties. The SSIIa GC/TT polymorphism explained more than 60% of the total variation in thermal properties, whereas the SSR and SNP of Wx gene explained as much as the SSIIa GC/TT of the total variation in retrogradation properties. Our study provides further support for the utilization of the GC/TT polymorphism in SSIIa. As shown in our study of 509 rice varieties, the GC/TT SNP could differentiate rice with high or intermediate GT from those with low GT in about 90% of cases. Using four primers in a single PCR reaction, the GC/TT polymorphism can be surveyed on a large scale. Thus, this SNP polymorphism can be very useful in marker-assisted selection for the improvement of GT and other physicochemical properties of rice. 相似文献
15.
Netzer C Freudenberg J Heinze A Heinze-Kuhn K Goebel I McCarthy LC Roses AD Göbel H Todt U Kubisch C 《Genomics》2008,91(6):503-507
We performed the first replication study for the reported association of the insulin receptor gene (INSR) with migraine with aura (MA). Two of 35 SNPs (rs1052371 and rs2860174) reached borderline significance (best uncorrected allelic p value of 0.052 for rs2860174) in stage 1 of our study (270 MA patients, 280 controls). As rs2860174 was 1 of the 5 SNPs with prior evidence of association, we also genotyped this SNP in our stage 2 sample (679 MA patients, 368 controls), and it was nonsignificant (allelic p value 0.478). The combined analysis of our samples showed just a nonsignificant trend for rs2860174 (p = 0.1). However, the joint analysis of our study and the initial study reporting an association—including 1278 Caucasian MA patients and 1337 Caucasian controls altogether—displayed a significant allelic p value of 0.005. In conclusion, further association studies for rs2860174 with even larger numbers of individuals are required to exclude or confirm definitely a small effect of this SNP on migraine susceptibility. 相似文献
16.
Allele mining exploits the deoxyribonucleic acid (DNA) sequence of one genotype to isolate useful alleles from related genotypes.
The international project to sequence the genome of Oryza sativa L cv. Nipponbare will make allele mining possible for all genes of rice and possibly related cereals. We used a rice calmodulin
gene, a rice gene encoding a late embryogenesis-associated protein, and salt-inducible rice gene to optimize the polymerase
chain reaction (PCR) for allele mining of stress tolerance genes on identified accessions of rice and related germplasm. Two
sets of PCR primers were designed for each gene. Primers based on the 5′ and 3′ untranslated region of genes were found to
be sufficiently conserved so as to be effective over the entire range of germplasm in rice for which the concept of allelism
is applicable. However, the primers based on the adjacent amino (N) and carboxy (C) termini amplify additional loci. 相似文献
17.
Twenty-six accessions of wildArachis species and domesticated peanuts,A. hypogaea, introduced from South America were analyzed for random amplified polymorphic DNA (RAPD). The objective of the study was to investigate inter- and intraspecific variation and affinities among species of sect.Arachis which have been proposed as possible progenitors for the domesticated peanut. Ten primers resolved 132 DNA bands which were useful for separating species and accessions. The most variation was observed among accessions ofA. cardenasii andA. glandulifera whereas the least amount of variation was observed inA. hypogaea andA. monticola. The two tetraploid species could not be separated by using RAPDs.Arachis duranensis was most closely related to the domesticated peanut and is believed to be the donor of the A genome. The data indicated thatA. batizocoi, a species previously hypothesized to contribute the B genome toA. hypogaea, was not involved in its evolution. The investigation showed that RAPDs can be used to analyze both inter- and intraspecific variation in peanut species. Southern hybridization of RAPD probes to blots containing RAPD of theArachis species provided information on genomic relationships and revealed the repetitive nature of the amplified DNA. 相似文献
18.
He XP Xu XW Zhao SH Fan B Yu M Zhu MJ Li CC Peng ZZ Liu B 《Molecular biology reports》2009,36(5):1175-1180
Lpin1 deficiency prevents normal adipose tissue development and remarkably reduces adipose tissue mass, while overexpression of
the Lpin1 gene in either skeletal muscle or adipose tissue promotes adiposity in mice. However, little is known about the porcine Lpin1 gene. In the present study, a 5,559-bp cDNA sequence of the porcine Lpin1 gene was obtained by RT-PCR and 3′RACE. The sequence consisted of a 111-bp 5′UTR, a 2,685-bp open reading frame encoding
a protein of 894 amino acids and a 2,763-bp 3′UTR. Semi-quantitative RT-PCR analysis revealed that Lpin1 had a high level of expression in the liver, spleen, skeletal muscle and fat, a low level of expression in the heart, lung
and kidney. The porcine Lpin1 gene was assigned to 3q21-27 by using the somatic cell hybrid panel (SCHP) and the radiation hybrid (IMpRH) panel. One C93T
single nucleotide polymorphism (SNP) was identified and genotyped using the TaqI PCR-RFLP method. Association analysis between the genotypes and fat deposition traits suggested that different genotypes
of the Lpin1 gene were associated with percentage of leaf fat and intramuscular fat. 相似文献
19.
Reiko Motohashi Eiichi Ohtsubo Hisako Ohtsubo 《Molecular & general genetics : MGG》1996,250(2):148-152
We isolated members of the retroposon family p-SINE1 in rice and found that one member contained an insertion. A 3-bp sequence at the insertion site within p-SINE1 appeared duplicated. The insertion sequence, 1536 bp in length, carried imperfect inverted repeats of about 13 bp at its termini which begin with 5-CACTA--- -3; these repeats are similar to those found in members of theEn/Spm transposable element family. These results indicate that the insertion sequence is a transposable element belonging to theEn/Spm family and is thus namedTnr3 (transposable element inrice no.3). In fact,Tnr3 carried long subterminal regions containing direct and inverted repeats of short DNA sequences of 15 bp, another characteristic of theEN/Spm family. The subterminal repeat sequences inTnr3 are, however, of two kinds, although they share homology with each other.Tnr3 and its relatives were present in multiple copies in rice. Considering the length ofTnr3, it cannot represent an autonomous type element, but is a non-autonomous element probably derived by deletion from an autonomous transposon. 相似文献
20.
GWAS has facilitated greatly the discovery of risk SNPs associated with complex diseases. Traditional methods analyze SNP individually and are limited by low power and reproducibility since correction for multiple comparisons is necessary. Several methods have been proposed based on grouping SNPs into SNP sets using biological knowledge and/or genomic features. In this article, we compare the linear kernel machine based test (LKM) and principal components analysis based approach (PCA) using simulated datasets under the scenarios of 0 to 3 causal SNPs, as well as simple and complex linkage disequilibrium (LD) structures of the simulated regions. Our simulation study demonstrates that both LKM and PCA can control the type I error at the significance level of 0.05. If the causal SNP is in strong LD with the genotyped SNPs, both the PCA with a small number of principal components (PCs) and the LKM with kernel of linear or identical-by-state function are valid tests. However, if the LD structure is complex, such as several LD blocks in the SNP set, or when the causal SNP is not in the LD block in which most of the genotyped SNPs reside, more PCs should be included to capture the information of the causal SNP. Simulation studies also demonstrate the ability of LKM and PCA to combine information from multiple causal SNPs and to provide increased power over individual SNP analysis. We also apply LKM and PCA to analyze two SNP sets extracted from an actual GWAS dataset on non-small cell lung cancer. 相似文献