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1.
V. H. Beaumont J. Mantet T. R. Rocheford J. M. Widholm 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1996,93(4):606-612
The F2 generations from two maize crosses were used to compare the ability of RAPD and RFLP marker systems to create a genetic linkage map. Both RFLPs and RAPDs were shown to provide Mendelian-type markers. Most of the RFLPs (80%) could be placed with a good level of certainty (LOD>4) on the genetic linkage map. However, because of their dominant nature, only between 37% and 59% of the RAPDs could be placed with such a LOD score. The use of combined data from RFLPs and RAPDs increases the level of information provided by RAPDs and allows the creation of a combined RFLP/RAPD genetic linkage map. Thus, the RAPD technique was found to be a powerful method to provide improved probes coverage on a previously created RFLP map and to locate markers linked to chromosomal regions of interest. 相似文献
2.
Quantitative trait loci influencing protein and starch concentration in the Illinois Long Term Selection maize strains 总被引:15,自引:0,他引:15
I. L. Goldman T. R. Rocheford J. W. Dudley 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,87(1-2):217-224
A study was initiated to determine the number, chromosomal location, and magnitude of effect of QTL (quantitative trait loci or locus depending on context) controlling protein and starch concentration in the maize (Zea mays L.) kernel. Restriction fragment length polymorphism (RFLP) analysis was performed on 100 F3 families derived from a cross of two strains, Illinois High Protein (IHP), X Illinois Low Protein (ILP), which had been divergently selected for protein concentration for 76 generations as part of the Illinois Long Term Selection Experiment. These families were analyzed for kernel protein and starch in replicated field trials during 1990 and 1991. A series of 90 genomic and cDNA clones distributed throughout the maize genome were chosen for their ability to detect RFLP between IHP and ILP. These clones were hybridized with DNA extracted from the 100 F3 families, revealing 100 polymorphic loci. Single factor analysis of variance revealed significant QTL associations of many loci with both protein and starch concentration (P < 0.05 level). Twenty-two loci distributed on 10 chromosome arms were significantly associated with protein concentration, 19 loci on 9 chromosome arms were significantly associated with starch concentration. Sixteen of these loci were significant for both protein and starch concentration. Clusters of 3 or more significant loci were detected on chromosome arms 3L, 5S, and 7L for protein concentration, suggesting the presence of QTL with large effects at these locations. A QTL with large additive effects on protein and starch concentration was detected on chromosome arm 3L. RFLP alleles at this QTL were found to be linked with RFLP alleles at the Shrunken-2 (Sh2) locus, a structural gene encoding the major subunit of the starch synthetic enzyme ADP-glucose pyrophosphorylase. A multiple linear regression model consisting of 6 significant RFLP loci on different chromosomes explained over 64 % of the total variation for kernel protein concentration. Similar results were detected for starch concentration. Thus, several chromosomal regions with large effects may be responsible for a significant portion of the changes in kernel protein and starch concentration in the Illinois Long Term Selection Experiment. 相似文献
3.
Y. Tadmor F. Azanza T. Han T. R. Rocheford J. A. Juvik 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1995,91(3):489-494
RFLP marker data from an F23 population derived from a cross between a sugary1 (su1) and a sugary enhancer1 (su1, sel) inbred were used to construct a genetic linkage map of maize. This map includes 93 segregating marker loci distributed throughout the maize genome, providing a saturated linkage map that is suitable for linkage analysis with quantitative trait loci (QTL). This population, which has been immortalized in the form of sibbed F23 families, was derived from each of the 214 F2 plants and along with probe data are available to the scientific community. QTL analysis for kernel sucrose (the primary form of sugar) concentration at 20 days after pollination (DAP) uncovered the segregation of seven major QTL influencing sucrose concentration; a locus linked to umc36a described the greatest proportion of the variation (24.7%). Since maltose concentration has previously been reported to be associated with the se1 phenotype, an analysis of probe associations with maltose concentration at 40 DAP was also conducted. The highly significant association of umc36a with maltose and sucrose concentrations provided evidence that this probe is linked to se1. Phenotypic evaluation for the se1 genotype in each F23 family enabled us to map the gene 12.1 cM distal to umc36a. In contrast to previous work where se1 was reported to be located on chromosome four, our data strongly suggest that the sugary enhancer1 locus maps on the the distal portion of the long arm of chromosome 2 in the maize genome. 相似文献
4.
The effect of partial and total drought on the macroinvertebrate communities of three small Danish streams 总被引:2,自引:2,他引:0
Torbert Moth Iversen Peter Wiberg-Larsen Søren Birkholm Hansen Frode S. Hansen 《Hydrobiologia》1978,60(3):235-242
Three cases of partial or total drought were studied. A two weeks' stop of water flow with reduced water level and stagnant
water was survived by most stream species. Only the population of Baetis rhodani Pict. was almost eliminated.
An unprecedented drought of 2-3 months reduced numbers of stream species. The differential effects are discussed in relationship
to the behaviour, life cycle and physiology of the individual species.
After the drought many invaders were found, but most disappeared rapidly. Only Asellus aquaticus L. maintained a population in the stream.
In an intermittent stream with 3–4 months' drought no changes were observed, and many species were the same as those which
survived in the second stream.
It is concluded that the consequences of an increasing frequency of drought, for example due to increasing ground water use,
will depend on the species normally present and on the season and duration of the drought. 相似文献
5.
Irregular patterns of transgene silencing in allohexaploid oat 总被引:7,自引:0,他引:7
Pawlowski Wojciech P. Torbert Kimberly A. Rines Howard W. Somers David A. 《Plant molecular biology》1998,38(4):597-607
An irregular pattern of transgene silencing was revealed in expression and inheritance studies conducted over multiple generations following transgene introduction by microprojectile bombardment of allohexaploid cultivated oat (Avena sativa L.). Expression of two transgenes, bar and uidA, delivered on the same plasmid was investigated in 23 transgenic oat lines. Twenty-one transgenic lines, each derived from an independently selected transformed tissue culture, showed expression of both bar and uidA while two lines expressed only bar. The relationship of the transgenic phenotypes to the presence of the transgenes in the study was determined using (1) phenotypic scoring combined with Southern blot analyses of progeny, (2) coexpression of the two transgenic phenotypes since the two transgenes always cosegregated, and (3) reactivation of a transgenic phenotype in self-pollinated progenies of transgenic plants that did not exhibit a transgenic phenotype. Transgene silencing was observed in 19 of the 23 transgenic lines and resulted in distorted segregation of transgenic phenotypes in 10 lines. Silencing and inheritance distortions were irregular and unpredictable. They were often reversible in a subsequent generation of self-pollinated progeny and abnormally segregating progenies were as likely to trace back to parents that exhibited normal segregation in a previous generation as to parents showing segregation distortions. Possible causes of the irregular patterns of transgene silencing are discussed. 相似文献
6.
Commerford SR Vargas L Dorfman SE Mitro N Rocheford EC Mak PA Li X Kennedy P Mullarkey TL Saez E 《Molecular endocrinology (Baltimore, Md.)》2007,21(12):3002-3012
The liver X receptors (LXRalpha and beta) are nuclear receptors that coordinate carbohydrate and lipid metabolism. Treatment of insulin-resistant mice with synthetic LXR ligands enhances glucose tolerance, inducing changes in gene expression expected to decrease hepatic gluconeogenesis (via indirect suppression of gluconeogenic enzymes) and increase peripheral glucose disposal (via direct up-regulation of glut4 in fat). To evaluate the relative contribution of each of these effects on whole-body insulin sensitivity, we performed hyperinsulinemic-euglycemic clamps in high-fat-fed insulin-resistant rats treated with an LXR agonist or a peroxisome proliferator-activated receptor gamma ligand. Both groups showed significant improvement in insulin action. Interestingly, rats treated with LXR ligand had lower body weight and smaller fat cells than controls. Insulin-stimulated suppression of the rate of glucose appearance (Ra) was pronounced in LXR-treated rats, but treatment failed to enhance peripheral glucose uptake (R'g), despite increased expression of glut4 in epididymal fat. To ascertain whether LXR ligands suppress hepatic gluconeogenesis directly, mice lacking LXRalpha (the primary isotype in liver) were treated with LXR ligand, and gluconeogenic gene expression was assessed. LXR activation decreased expression of gluconeogenic genes in wild-type and LXRbeta null mice, but failed to do so in animals lacking LXRalpha. Our observations indicate that despite inducing suggestive gene expression changes in adipose tissue in this model of diet-induced insulin resistance, the antidiabetic effect of LXR ligands is primarily due to effects in the liver that appear to require LXRalpha. These findings have important implications for clinical development of LXR agonists as insulin sensitizers. 相似文献
7.
The genetic architecture of response to long-term artificial selection for oil concentration in the maize kernel 总被引:13,自引:0,他引:13
Laurie CC Chasalow SD LeDeaux JR McCarroll R Bush D Hauge B Lai C Clark D Rocheford TR Dudley JW 《Genetics》2004,168(4):2141-2155
In one of the longest-running experiments in biology, researchers at the University of Illinois have selected for altered composition of the maize kernel since 1896. Here we use an association study to infer the genetic basis of dramatic changes that occurred in response to selection for changes in oil concentration. The study population was produced by a cross between the high- and low-selection lines at generation 70, followed by 10 generations of random mating and the derivation of 500 lines by selfing. These lines were genotyped for 488 genetic markers and the oil concentration was evaluated in replicated field trials. Three methods of analysis were tested in simulations for ability to detect quantitative trait loci (QTL). The most effective method was model selection in multiple regression. This method detected approximately 50 QTL accounting for approximately 50% of the genetic variance, suggesting that >50 QTL are involved. The QTL effect estimates are small and largely additive. About 20% of the QTL have negative effects (i.e., not predicted by the parental difference), which is consistent with hitchhiking and small population size during selection. The large number of QTL detected accounts for the smooth and sustained response to selection throughout the twentieth century. 相似文献
8.
Upadyayula N da Silva HS Bohn MO Rocheford TR 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2006,112(4):592-606
Maize (Zea mays L.) ear inflorescence architecture is directly relevant to grain yield components, and tassel architecture is relevant to
hybrid seed production. The objectives of this study were to (1) determine heritabilities and correlations of a comprehensive
set of tassel and ear inflorescence architecture traits in a set of (Illinois Low Protein×B73) B73 S1 families, (2) identify chromosomal positions of QTL affecting tassel and ear architecture, and (3) identify possible candidate
genes associated with these QTL. For tassel traits, the number of detected QTL ranged from one to five, and explained between
6.5 and 35.9% of phenotypic variation. For ear traits, the number of detected QTL ranged from one to nine and phenotypic variation
explained by those QTL varied between 7.9 and 53.0%. We detected QTL for tassel architecture traits that required calculation
of ratios from measured traits. Some of these calculated traits QTL were detected in regions that did not show QTL for the
measured traits, suggesting that calculation of ratios may reveal developmentally relevant patterns of tassel architecture.
We detected a QTL on chromosome 7 for tassel branch number near the gene ramosa1 (ra1), which is known to control tassel branch number, making ra1 a candidate gene for tassel branch number. We detected QTL for several traits on chromosomes 6, 8, and 9, where no inflorescence
architecture genes have been mapped, thus providing initial information towards new gene discovery for control of inflorescence
architecture. 相似文献
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