Uniform Probability Response Spectra for Selecting Site Specific Design Motions

In the majority of the current building codes, the shape of a design spectrum is defined by considering only the local soil conditions. This paper examines the validity of this simplification. In particular, it is shown how effects of deep soil or rock soil conditions on uniform probability site specific spectra can be simulated by varying the geological site conditions (depth of sediments) and the distance from the fault. On the basis of the results presented in the paper and similar results from earlier papers considering the effects of the choice of the geometry of the model fault and the assumed rupture area, as well as the seismic moment rate, the maximum magnitude, the b-value, and the confidence of the prediction, it is concluded that the shapes of design spectra should not be determined only on the basis of the local soil conditions

Molecular characterization of chemical mutagenesis induced diversity in elite maize germplasm

Three classical breeding Iowa Super Stiff Stalk (SSS) inbred lines B37, B73 and B84, one Lancaster inbred Oh43 and mutant lines obtained by chemical mutagenesis followed by mutation breeding as follows: two of B37 and four of Oh43 were selected for molecular characterization. The mutant inbred lines were chosen because in addition to the improved GCA and SCA for grain yield, proven by their predominance in the Bulgarian breeding programs, they showed shifts in the flowering time as compared to the initial inbreds. Molecular markers (micro satellites and other PCR-based DNA markers) were used for characterization of maize genotypes and determination of the induced by chemical mutagenesis genetic variability in maize germplasm. The tested nine SSR markers (umc 1001, umclO14, umcl057, umcll81, umcl0lS, umc 1029. umcl003, umc 1033 and umcl035) can discriminate between the initial classical breeding inbred lines and the originating mutant inbreds. Allelic diversity was also studied by PCR amplification with specifically de-signed primers in the coding regions and flanking sequence of two genes: dwarf8 (d&: chromosome 1, 198.5 cM), and indeterminate l (id1; chromosome 1. 175.0 cM). These are considered candidate genes for variation in plant height and/or flowering time, based on mutant phenotypes and chromosomal locations near major QTLs. Single nucleotide polymorphisms and indels were detected in the region flanking the SH2 domain of dwarf8 gene in some of the mutant inbreds as a result of SSCP and sequencing analyses. However, these polymorphisms could not be associated with the observed variations in flowering time. PCR analysis of the promoter region dwarf8 showed a variant fragment of about 1 kb in the inbred line Oh43 that was not present in any other initial and mutant in-bred lines included in the study. PCR amplification of the 5' end of the Id1 coding sequence revealed polymorphic bands in the mutant lines XM535, XM521, XM250-l, XM98-8 and XM85-105, as well as in the classical breeding line B73. The data, presented here demonstrate the usefulness of chemical mutagenesis for generation of genetic diversity within the elite maize germplasm. Some of this variation may affect the major genes in the QTLs. Our initial data revealed mutagenesis induced polymorphisms in the coding sequences of two important for the determination of flowering time transcription factors. Further molecular analyses of the proposed model systems may complement the trait association efforts and will help to directly identify the major genes in the QTLs

ALLELE DISTRIBUTION AT MICROSATELLITE LOCUS XGWM 261 MARKING THE DWARFING GENE RHT8 IN HEXAPLOID WHEAT FROM BULGARIAN AND BELGIAN GENE BANK COLLECTIONS AND ITS APPLICATION IN BREEDING PROGRAMS

ABSTRAC