A multicenter study has been carried out to characterize 13 polymorphic short tandem repeat (STR) systems located on the male specific part of the human Y chromosome (DYS19, DYS288, DYS385, DYS388, DYS389I/II, DYS390, DYS391, DYS392, DYS393, YCAI, YCAII, YCAIII, DXYS156Y). Amplification parameters and electrophoresis protocols including multiplex approaches were compiled. The typing of non-recombining Y loci with uniparental inheritance requires special attention to population substructuring due to prevalent male lineages. To assess the extent of these subheterogeneities up to 3825 unrelated males were typed in up to 48 population samples for the respective loci. A consistent repeat based nomenclature for most of the loci has been introduced. Moreover we have estimated the average mutation rate for DYS19 in 626 confirmed fatherson pairs as 3.2 x 10(-3) (95% confidence interval limits of 0.00041-0.00677), a value which can also be expected for other Y-STR loci with similar repeat structure. Recommendations are given for the forensic application of a basic set of 7 STRs (DYS19, DYS3891, DYS389II, DYS390, DYS391, DYS392, DYS393) for standard Y-haplotyping in forensic and paternity casework. We recommend further the inclusion of the highly polymorphic bilocal Y-STRs DYS385, YCAII, YCAIII for a nearly complete individualisation of almost any given unrelated male individual. Together, these results suggest that Y-STR loci are useful markers to identify males and male lineages in forensic practice.

By means of a multicenter study, a large number of males have been characterized for Y-chromosome specific short tandem repeats (STRs) or microsatellites. A complete summary of the allele frequency distributions for these Y-STRs is presented in the Appendix. This manuscript describes in more detail some of the population genetic and evolutionary aspects for a restricted set of seven chromosome Y STRs in a selected number of population samples. For all the chromosome Y STRs markedly different region-specific allele frequency distributions were observed, also when closely related populations were compared. Haplotype analyses using AMOVA showed that when four different European male groups (Germans, Dutch, Swiss, Italians) were compared, less than 10% of the total genetic variability was due to differences between these populations. Nevertheless, these pairwise comparisons revealed significant differences between most population pairs. Assuming a step-wise mutation model and a mutation frequency of 0.21%, it was estimated that chromosome Y STR-based evolutionary lines of descent can be reliably inferred over a time-span of only 1950 generations (or about 49,000 years). This reduces the reliability of the inference of population affinities to a historical, rather than evolutionary time scale. This is best illustrated by the construction of a human evolutionary tree based on chromosome Y STRs in which most of the branches connect in a markedly different way compared with trees based on classical protein polymorphisms and/or mtDNA sequence variation. Thus, the chromosome Y STRs seem to be very useful in comparing closely related populations which cannot probably be separated by e.g. autosomal STRs. However, in order to be used in an evolutionary context they need to be combined with more stable Y-polymorphisms e.g. base-substitutions.

Alleles of the STR systems HumFES/FPS, HumVWA and HumD21S11 were sequenced and analyzed. Sequence data revealed 3 different systems concerning the complexity of their sequence structure. HumFES/FPS belongs to the STR polymorphism with a simple repeat structure. Only 2 subtypes were found with a base substitution in the 5'-flanking region and no variation in the repeat region. In the STR system HumVWA the sequence structure of the repeat region is more complex, because 2 tetranucleotide units TCTA and TCTG were present. Additionally allele 14 revealed a completely different sequence structure leading to a different electrophoretic mobility. The repeat region of HumD21S11 is compound in structure. The possibility of variation at 3 positions leads to the occurrence of microheterogeneities in fragments of apparent length. In the upper allele range alleles arise with an additional incomplete TA-repeat.

Y-chromosomal short tandem repeats (STRs) are used for the study of male aspects of human evolution as well as for forensic applications and paternity testing. Both applications require an understanding of the underlying mutational mechanisms that create variability. We describe complex mutations at the substructured DYS390 STR locus in 97 natives of the New Guinea/Australian region. Sequencing of short alleles in these populations indicates multirepeat deletions. All samples are further characterized using the five additional Y-STR loci DYS19, DXYS156-Y, DYS391, DYS392, and DYS393. Phylogenetic analysis of the resulting haplotypes yields ethnically specific clusters predating the settlement of Australia and Papua New Guinea (although archaic Homo sapiens or Homo erectus lineages are absent). The phylogeny confirms that DYS390 violates the stepwise mutation model and demonstrates that the DYS390 locus mutates relatively rapidly and retains its variability after structural change.

We amplified, via PCR, DNA segments from intron 1 of the tyrosine hydroxylase gene (TH01) and intron 40 of the von Willebrand factor gene (VWA) in ten nonhuman primate genera. In humans both introns contain polymorphic microsatellites with tetrameric repeats. Compared to the allelic ranges in human populations relatively short repeat arrays could be detected for the nonhuman primates typed, presumably reflecting an ancient precursor state at both microsatellite loci. Furthermore, our results provide evidence for an association of the average number of repeats present in different primate genera and their divergence time from man. DNA sequencing of VWA orthologues revealed a relatively high variability in the arrangement of repeats in the 5'-repeat arrays, the generation of which could probably be explained by polar mutational events.

Increasing the stearic acid content to improve soybean [Glycine max (L) Merr] oil quality is a desirable breeding objective for food-processing applications. Although a saturated fatty acid, stearic acid has been shown to reduce total levels of blood cholesterol and offers the potential for the production of solid fat products (such as margarine) without hydrogenation. This would result in the reduction of the level of trans fat in food products and alleviate some current health concerns. A segregating F2 population was developed from the cross between Dare, a normal stearic acid content cultivar, and FAM94-41, a high stearic acid content line. This population was used to assess linkage between the Fas locus and simple sequence repeat (SSR) markers. Three SSR markers, Satt070, Satt474, and Satt556, were identified to be associated with stearic acid (P < 0.0001, r 2 > 0.61). A linkage map consisting of the three SSR markers and the Fas locus was then constructed in map order, Fas, Satt070, Satt474, and Satt556, with a LOD score of 3.0. Identification of these markers may be useful in molecular marker-assisted breeding programs targeting modifications in soybean fatty acids.

Plant breeding research efforts are currently focused on developing breeding procedures to decrease the saturated FA palmitic acid (16:0) and the PUFA linolenic acid (18:3) in U.S. soybean cultivars. Soybean oil with lower 16:0 may provide cardiovascular benefits to health-conscious consumers, and lower 18:3 could contribute to better flavor and stability of the oil. The purpose of this study was to determine genetic parameters that indicate the potential for breeding success and to characterize the correlated effect of the incorporation of the modified oil traits on the agronomic and seed quality traits of a soybean breeding population formed from a cross between the soybean cultivar Anand (normal) and germplasm N97-3708-13 (low 16:0, low 18:3). Although lines with only one modified oil quality trait (low 16:0 or 18:3) are useful as parents, commercial utilization requires productive cultivars with the combination of both oil traits. This paper shows the ease with which they may be combined with seed yield and other traits. Measurements were obtained from 179 F 2 single plants grown in 1999 and 121 F 2:4 lines grown in replicated plots in 2000. Modified FA lines were developed with ca. 4% 16:0 and 18:3, respectively. Very weak positive correlations were found between 16:0 concentration and seed yield (r = 0.12) and between 16:0 and seed oil concentration (r = 0.13). No correlation was found between 18:3 levels and seed yield, or between 18:3 levels and seed oil concentration. These results indicate that breeding for reduced 16:0 and 18:3 should not have a negative impact on seed yield or oil concentration. 16:0 and 18:3 had moderately high heritabilities of 0.65 and 0.73, respectively. This indicates that breeders using low 16:0, low 18:3 germplasm in crosses with normal, elite lines can expect to recover low 16:0 and low 18:3 in pure line progenies via selection and generation advancement of F 2 individuals that express low levels of these FA.

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