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Phenotypic stereotypes are traits, often polygenic, that have been stringently selected to conform to specific criteria. In dogs, Canis familiaris, stereotypes result from breed standards set for conformation, performance (behaviors), etc. As a consequence, phenotypic values measured on a few individuals are representative of the breed stereotype. We used DNA samples isolated from 148 dog breeds to associate SNP markers with breed stereotypes. Using size as a trait to test the method, we identified six significant quantitative trait loci (QTL) on five chromosomes that include candidate genes appropriate to regulation of size (e.g., IGF1, IGF2BP2 SMAD2, etc.). Analysis of other morphological stereotypes, also under extreme selection, identified many additional significant loci. Less well-documented data for behavioral stereotypes tentatively identified loci for herding, pointing, boldness, and trainability. Four significant loci were identified for longevity, a breed characteristic not under direct selection, but inversely correlated with breed size. The strengths and limitations of the approach are discussed as well as its potential to identify loci regulating the within-breed incidence of specific polygenic diseases.

Genetic variation in functionally integrated skeletal traits can be maintained over 10 million years despite bottlenecks and stringent selection. Here, we describe an analysis of the genetic architecture of the canid axial skeleton using populations of the Portuguese Water Dog Canis familiaris) and silver fox (Vulpes vulpes). Twenty-one skeletal metrics taken from radiographs of the forelimbs and hind limbs of the fox and dog were used to construct separate anatomical principal component (PC) matrices of the two species. In both species, 15 of the 21 PCs exhibited significant heritability, ranging from 25% to 70%. The second PC, in both species, represents a trade-off in which limb-bone width is inversely correlated with limb-bone length. PC2 accounts for approximately 15% of the observed skeletal variation, ~30% of the variation in shape. Many of the other significant PCs affect very small amounts of variation (e.g., 0.2-2%) along trade-off axes that partition function between the forelimbs and hind limbs. These PCs represent shape axes in which an increase in size of an element of the forelimb is associated with a decrease in size of an element of the hind limb and vice versa. In most cases, these trade-offs are heritable in both species and genetic loci have been identified in the Portuguese Water Dog for many of these. These PCs, present in both the dog and the fox, include ones that affect lengths of the forelimb versus the hind limb, length of the forefoot versus that of the hind foot, muscle moment (i.e., lever) arms of the forelimb versus hind limb, and cortical thickness of the bones of the forelimb versus hind limb. These inverse relationships suggest that genetic regulation of the axial skeleton results, in part, from the action of genes that influence suites of functionally integrated traits. Their presence in both dogs and foxes suggests that the genes controlling the regulation of these PCs of the forelimb versus hind limb may be found in other tetrapod taxa.

Mariner elements, a family of DNA-mediated transposable elements with short, inverted terminal repeats, have been reported in a wide variety of arthropods, as well as planarians, nematodes, and humans. No such element has been reported in a plant. Here we report a mariner element in the plant soybean (Glycine max (L.) Merr.). Although this sequence belongs to the mariner family, it is clearly distinct from previously reported mariner-like elements, as well as from the Tc1 transposon family. Novel aspects of its sequence could be useful as a starting point to identify mariner-like elements in new organisms, and it may prove useful in creating a transformation vector for plants.

Soil waterlogging is a major environmental stress that suppresses soybean [Glycine max (L.) Merr.] growth and yield. Our objective was to identify quantitative trait loci (QTL) associated with the tolerance of soybean to soil waterlogging. We subjected 208 lines of two recombinant inbred (RI) populations, `Archer' x `Minsoy' and `Archer' x `Noir I', to 2 wk of waterlogging when the plants were at the early flowering stage. The control plants were not flooded. The experiment was conducted in three environments: Columbus, OH, in 1997 and 1998 and Wooster, OH, in 1998. We identified a single QTL, linked to marker Sat_064, from the Archer parent which was associated with improved plant growth (from 11-18%) and grain yields (from 47-180%) in waterlogged environments. This highly significant QTL (P = 0.02-0.000001) was identified in both RI populations and at both Columbus 1997 and 1998 environments, but not at the Wooster 1998 environment. The differences in soil type and flooding treatment (stagnant versus moving water) could have contributed to the lack of QTL identification at the Wooster 1998 environment. The Sat_064 QTL was uniquely associated with waterlogging tolerance and was not associated with maturity, normal plant height or grain yields. The Sat_064 marker maps close to the Rps4 gene for Phytophthora (Phytophthora sojae M.J. Kaufmann & J.W. Gerdemann) resistance; however, since Archer does not contain the Rps4 resistance allele, it is probably not a disease tolerance QTL. Near isogenic lines with and without the Sat_064 marker have been developed and are being field tested under waterlogging conditions to confirm the association of the QTL with the tolerance of soybean to waterlogging stress., PERIODIC FLOODING during the growing season adversely affects soybean growth and grain production in many areas of the USA and the rest of the world. (Stanley et al., 1980; Oosterhuis [...]

Based on the results given in a previous abstract, a more extensive study was performed to assess the genetic basis of seed abortion and reproduction in soybean. For this study, reproductive data were obtained from two replications of three different RI populations derived from the three parents Minosy, Noir 1 and Archer grown under typical agronomic conditions. This study surveyed a more extensive list of reproductive parameters (number of nodes per plant, nodal length, number of fruits per node, nodal position of fruits, number of fruits/plant, number of ovules per pod, number of filled seeds per pod, seed/ovule, and developmental stage and position of abortions). In addition, a variety of agronomic traits (seed number, seed weight, total yield, leaf shape, oil content of seeds, number of flowers per plant, protein content of seed, etc.) were measured in the same experiment. All reproductive and agronomic traits were compared with three existing genetic linkage maps. of genotypes from these RI populations. Quantitative trait loci (QTLs) responsible for the variation in reproductive traits were identified and also analyzed for interactions with other QTLs. These results were compared with data (given in previous abstract) obtained from different environmental conditions (Utah vs. Minnesota).

Genetic basis of embryo abortion in Glycine max was analzyed using a large Recombinant Inbred (RI) population. RI lines (including three replicates), parental lines (Minsoy & Noir 1) and 'Check' cultivars were planted in hill plots. Fifty fruits from each hill were analyzed for reproductive, quantitative traits (number of ovules per pod, number of filled seeds per pod, seed/ovule, and developmental stage and position of abortions). Parental lines differed significantly for traits. Average values for the RI population were intermediate between the parents. Some segregants had high frequencies of four ovules or seeds per pod, whereas parents and 'Checks' did not. There was a positive correlation between yield and ovules per pod and between seed number and ovules per pod. No correlation was observed between variation in pod size and seed/ovule. If abortion occurred within a pod there was a greater probability that another abortion would occur at the same developmental stage. Most abortions fell in the first position within the fruit. Abortions were observed at all developmental stages, but primarily occurred at two of four stages. Six significant QTLs were associated with reproductive traits. QTLs accounted for 36% of the variation in ovule or seed number. Two QTLs were involved in interactions with another locus.

The discovery of non-random chromosome segregation is discussed from the perspective of what was known in 1965 and 1966. The distinction between daughter, parent or grandparent strands of DNA was developed in a bacterial system and led to the discovery that multiple copies of DNA elements of bacteria are not distributed randomly with respect to the age of the template strand. Experiments with higher eukaryotic cells demonstrated that during mitosis Mendel's laws were violated; and the initial serendipitous choice of eukaryotic cell system led to the striking example of non-random segregation of parent and grand-parent DNA template strands in primary cultures of cells derived from mouse embryos. Attempts to extrapolate these findings to established TC lines demonstrated that the property could be lost. Experiments using plant root tips demonstrated that the phenomenon exists in plants and that it was, at some level, under genetic control. Despite publication in major journals and symposia (Lark et al. (1966a); Lark (1967a; 1967b; 1969, 1969a; 1969b)) the potential implications of these findings were ignored for several decades. Here we explore possible reasons for the pre-maturity (Stent, 1972) of this discovery. [ABSTRACT FROM AUTHOR]

Purebred dogs are a valuable resource for genetic analysis of quantitative traits. Quantitative traits are complex, controlled by many genes that are contained within regions of the genome known as quantitative trait loci (QTL). The genetic architecture of quantitative traits is defined by the characteristics of these genes: their number, the magnitude of their effects, their positions in the genome and their interactions with each other. QTL analysis is a valuable tool for exploring genetic architecture, and highlighting regions of the genome that contribute to the variation of a trait within a population. [Copyright &y& Elsevier]