Showing papers in "Journal of Heredity in 1999"

Isolation and inheritance of novel microsatellites in Chinook Salmon (Oncorhynchus tschawytscha)

Abstract: We describe the isolation, PCR amplification, and characterization of 10 new microsatellite loci (Ots-1–Ots-10) for the federally protected chinook salmon (Oncorhynchus tschawytscha). We investigate the inheritance and linkage of these loci as well as a previously published locus, Onem13, in families obtained from artificial crosses. Mendelian transmission is confirmed for 76 of 80 segregations observed. Of the four deviations, two appear to have resulted from gametic segregation distortion. The other two provide evidence for the existence of at least one null allele. We also identify ‘‘drop out’’ of large alleles in these two families owing to competitive PCR amplification of smaller alleles. There is no evidence for linkage between any pair of loci. One mutation observed at Ots-2 is reported and confirmed by DNA sequencing. We estimate the mutation rate at this locus to be 6.5 3 10–4 (95% confidence interval 3.6 3 10–3 to 1.6 3 10–4, respectively). Characterizing a mutant allele at Ots-2 offers the first step toward understanding mutation rates for chinook microsatellites. Owing to their Mendelian inheritance, these new loci provide reliable markers for high-resolution population genetics studies of this species.

Phylogenetic relationships, evolution, and genetic diversity of the domestic dog

Abstract: The spectacular diversity in size, conformation, and pelage that characterizes the domestic dog reflects not only the intensity of artificial selection but ultimately the genetic variability of founding populations. Here we review past molecular genetic data that are relevant to understanding the origin and phylogenetic relationships of the dog. DNA-DNA hybridization data show that the dog family Canidae diverged about 50 million years ago from other carnivore families. In contrast, the extant canids are very closely related and diverged from a common ancestor about 10 million years ago. The evidence supporting a close relationship of dogs with gray wolves is overwhelming. However, dogs are remarkably diverse in mitochondrial and nuclear genes. Mitochondrial DNA analysis suggests a more ancient origin of dogs than has been indicated by the fossil record. In addition, dogs have originated from or interbred with wolves throughout their history at different times and different places. We test the possibility of an independent domestication event in North America by analysis of mtDNA variation in the Xoloitzcuintli. This unusual breed is believed to have been kept isolated for thousands of years and may be one of the most ancient breeds in North America. Our results do not support a New World domestication of dogs nor a close association of the Xoloitzcuintli with other hair-less breeds of dogs. Despite their phenotypic uniformity, the Xoloitzcuintli has a surprisingly high level of mtDNA sequence variation. Other breeds are also genetically diverse, suggesting that dog breeds were often founded with a large number of dogs from outbred populations.

Brief communication. Isolation of microsatellite loci from a social lizard, Egernia stokesii, using a modified enrichment procedure

Abstract: An abnormal-leaf soybean [Glycine max (L.) Merr.] plant was observed in an F4:8 line at Urbana, Illinois, in the summer of 1992. Petiolules of the plant were shorter than normal and leaflet margins curled uniformly upward forming a cuppedshaped leaf. All progeny of the single plant exhibited leaf cupping. Laboratory analysis showed an absence of soybean mosaic and tobacco ringspot virus in the plants. Seeds from the progeny were bulked and designated line LN89-3502TP. Further observation of LN89-3502TP revealed dense pubescence on the short petiolule plants. The objective of this study was to determine the inheritance of the short petiolule trait of LN89-3502TP. In F2 populations derived from LN89-3502TP crossed with normal leaf-type cultivars, three petiolule phenotypes (short, intermediate, and normal) segregated in a 1:2:1 ratio. The 1:2:1 ratio was confirmed in the F2:3 families. These ratios indicate the short petiolule trait is controlled by a single gene showing incomplete dominance that we designated lc.

The Rift Valley complex as a barrier to gene flow for Anopheles gambiae in Kenya

Abstract: Recent studies of Anopheles gambiae, the principal mosquito vector of malaria in Africa, suggested that the eastern Rift Valley and its surrounding areas act as a barrier to gene flow. To quantify the unique effect of these areas on gene flow, we measured genetic variation within and between populations from each side of the Rift. Low differentiation was measured between populations on each side of the Rift (mean FST < 0.008, mean RST < 0.002). However, high differentiation was measured across the Rift (mean FST = 0.104; mean RST = 0.032). Genetic diversity within populations was lower in eastern populations, suggesting that the effective population sizes (Ne) of these populations were lower than those of western populations. We partitioned the overall differentiation across the Rift into three factors: variation in Ne between populations contributed 7-20%; distance contributed 10-30%, and the remainder, corresponding to the unique effect of the Rift was 50-80%. The Rift's effect was highly significant based on FST. The greater sensitivity of FST in measuring differentiation indicated that drift and not mutation generated the differences between populations. Restricted gene exchange across several hundred kilometers on the face of intense human transportation implies that active mosquito dispersal is the major form of migration, and that migration is a multistep process, where step length is relatively short.

Molecular mapping of genes affecting pubescence of cotton

Abstract: Upland cotton (Gossypium hirsutum L.) genotypes have varying densities of trichomes on the leaves and stems of mature plants, hence their species name. Most modern cotton cultivars are ‘‘smooth’’ with few if any trichomes. Absence of trichomes reduces the attractiveness of the cotton plant to some major insect pests, reducing reliance on pesticides. A detailed RFLP map was used to map genes affecting density of leaf and stem trichomes. Based on quantitative measures of young and mature leaves, four QTLs were mapped. A QTL on chromosome 6 that imparts dense leaf pubescence is inferred to be the t1 locus. A second QTL on chromosome 25, which is homoeologous to chromosome 6, fits the description of the t2 locus. Two additional QTLs, QLP1 and QLP2, explained significant phenotypic variation in leaf pubescence—these may represent the t3, t4, or t5 loci. Some QTLs appeared to be specific to particular developmental stages; for example, QLP1 reduced hairiness only in young leaves while QLP2 increased hairiness in mature leaves. A single locus associated with variation in trichome density on the stem did not correspond to the genes/QTLs affecting leaf trichomes, suggesting that these traits may largely be controlled by different genes. A widely used qualitative classification system for scoring trichome density (DTL) detected only the chromosome 6 locus and was apparently not sensitive enough to detect alleles such as t2 that had smaller phenotypic effects.

Brief communication. Microsatellite diversity in captive bottlenose dolphins (Tursiops truncatus)

Abstract: The utility of microsatellites for managing captive Tursiops truncatus was investigated. Specifically the level of genetic diversity among the loci examined and their usefulness for resolving paternity was assessed. Overall a relatively low level of genetic variation was found among captive dolphins. In addition, a high percentage of common alleles was found among dolphins belonging to different morphotypes (inshore versus offshore). The implications of these findings are discussed and suggestions are given for the use of genetic markers in captive propagation programs for T. truncatus.

Mitochondrial transcript processing and restoration of male fertility in T-cytoplasm maize

Abstract: Cytoplasmic male sterility (CMS) systems have been useful in the production of hybrid seed in a number of crops. The Texas or T-cytoplasmic male-sterile (cms-T) system was used extensively in the 1960s to eliminate the need for hand detasseling in hybrid maize production. As a consequence of the 1970 epidemic of southern corn leaf blight, cms-T is no longer widely used commercially. However, it has been developed as a model system to study the genetic and molecular mechanisms underlying male sterility and fertility restoration. Male sterility in T-cytoplasm maize results from the action of a T-cytoplasm-specific mitochondrial gene, T-urf13. Full (or partial) fertility restoration of T-cytoplasm maize is mediated by the Rf2 nuclear restorer in combination with one of three other restorers: Rf1, Rf8, or Rf*. Rf2 encodes a protein highly similar to mitochondrial aldehyde dehydrogenases; Rf1, Rf8, and Rf* each mediate discrete T-urf13 mitochondrial transcript processing events. To test the functionality of Rf1, Rf8, or Rf*, a T-cytoplasm transformation system is under development. AFLP bulk-segregant analysis has been used to identify DNA markers closely linked to the Rf8 locus. These tools will provide a foundation for determining mechanisms of nuclear-directed mitochondrial RNA processing and fertility restoration.

Parentage and kinship studies in an obligate brood parasitic bird, the brown-headed cowbird (Molothrus ater), using microsatellite DNA markers

Abstract: Recent studies suggest that single-locus microsatellite DNA markers have the potential to unambiguously resolve parentage among individuals in natural populations where maternity is known. However, their power for determining parentage when neither parent is known is unclear. Here we investigate the usefulness of microsatellite DNA markers to determine parentage in a brood parasitic bird, the brown-headed cowbird (Molothrus ater), where, for a given offspring, no a priori knowledge of either parent is available. Seven polymorphic microsatellite DNA markers isolated from brown-headed cowbirds and yellow warblers (Dendroica petechia) were used to genetically characterize an individually marked breeding population of male and female cowbirds at Delta Marsh, Manitoba. Forty-four males, 21 females, and 61 cowbird chicks were genotyped at seven loci using DNA amplified from blood and tissue samples. The mean exclusion probabilities pooled across all seven loci were 0.9964 for males and 0.9948 for females. Two null (non-amplifying) alleles at one locus were discovered and accounted for by constructing alternate nonoverlapping primer sets. Exclusion analyses performed using all individuals determined both paternity and maternity for 43 chicks and paternity only for 4 chicks. Another microsatellite locus was then used to determine paternity for three additional chicks. Relatedness analyses placed 12 of the 18 remaining chicks not assigned both maternity and paternity into four unique full sibling groups. Overall, 90.16% (55 of 61) of all offspring examined were placed into distinct parent/sibling groups, demonstrating that this marker set is extremely useful for parentage studies in this species.

Cryptic species of rockfishes (Sebastes: Scorpaenidae) in the Southern Hemisphere inferred from mitochondrial lineages

Abstract: We used mitochondrial DNA sequence variation of Sebastes from the southeastern Pacific and three localities in the South Atlantic to address long-standing systematic and evolutionary issues regarding the number of species in the Southern Hemisphere. Sequences of the hypervariable mitochondrial control region were obtained from 10 specimens of S. capensis from South Africa (n = 5) and from Tristan da Cunha Island (n = 5) and 27 of S. oculatus from Valparaiso, Chile (n = 10), and the Falkland Islands (n = 17). Results of the study include (1) significant levels of genetic differentiation among the sampled populations (phi ST = 0.225, P < .000001), thus indicating limited gene flow; (2) corroboration of the existence of two different lineages of austral Sebastes corresponding to S. capensis and S. oculatus; (3) finding that S. capensis is not restricted to Tristan da Cunha and South Africa, but is widespread across the South Atlantic; (4) the position of S. capensis as the ancestral lineage of the austral Sebastes; (5) the existence of a third evolutionary lineage with high levels of genetic divergence, particularly abundant in the south-western Atlantic, which may be recognized as a third austral species of Sebastes.

Organization of the canine major histocompatibility complex: current perspectives

Abstract: The dog is a valuable model for studying several human diseases as well as one of the most important models for organ transplantation. Important to understanding the pathophysiology or development of some of these diseases is an understanding of the canine major histocompatibility complex (MHC) or dog leukocyte antigen (DLA). Initial characterization of the DLA involved primarily cellular, serological, and biochemical analyses. Later a molecular analysis of the DLA region was begun. There are at least four complete class I genes: DLA-88, DLA-12, DLA-64, and DLA-79. DLA-88 is highly polymorphic, with more than 40 alleles obtained from an examination of 50 mixed breed dogs. The other class I loci are less polymorphic, with fewer than 12 alleles each. In the class II region there is one complete DRB gene called DLA-DRB1 with at least 24 alleles and one full-length DQB gene, DLA-DQB1, with 20 alleles characterized to date. DLA-DQA is less polymorphic with nine alleles and DLA-DRA appears monomorphic. Two highly polymorphic canine microsatellite markers, one located in the class I region and one located in the class II region, can be used to identify DLA-matched and -mismatched dogs within families for organ transplantation experiments. Future projects include mapping the DLA region by pulsed-field gel electrophoresis and using a recently constructed canine bacterial artificial chromosome (BAC) library to search for new genes within the DLA. The dog has been a useful model for understanding several human diseases such as gluten-sensitive enteropathy (Hall and Batt 1990), rheumatoid arthritis (Halliwell et al. 1972), narcolepsy (Tafti et al. 1996), and systemic lupus erythematosus (Lewis and Schwartz 1971, Teichner et al. 1990), as well as an important model for solid organ and hematopoietic stem cell transplantation (Storb and Deeg 1985). Much of the impetus behind efforts to characterize the canine MHC comes from its importance in transplantation. In spite of the dog's importance in studying human disease and in immunology, molecular analysis of the DLA has lagged behind that of the mouse and human as well as several agricultural animals.

The yellow variegated mutant of Arabidopsis is plastid autonomous and delayed in chloroplast biogenesis

Abstract: The yellow variegated mutant of Arabidopsis thaliana is characterized by bright-yellow true leaves that turn green- and white-sectored as leaf development proceeds. Variegation is due to the action of a nuclear recessive gene. Whereas cells in the green sectors contain morphologically normal chloroplasts, cells in the yellow and white sectors are heteroplastidic and contain plastids with rudimentary lamellar structures, as well as some normal-appearing chloroplasts. This indicates that plastids in yellow variegated are affected differently by the nuclear mutation (the mutant is "plastid autonomous"). Genetic analyses have revealed that yellow variegated is an allele of the var2 locus, and that defective plastids are not maternally inherited. The traits of plastid autonomy and lack of maternal inheritance of the plastid defect set var2 apart from other nuclear gene-induced variegations and define a novel class of variegation mutant. The primary lesion in var2 probably does not involve a blockage in the pathways of pigment biosynthesis. Under high temperatures or low light conditions, plant growth is retarded and mutant plants are nearly all-green. Considered together, our data suggest that var2 is delayed in chloroplast biogenesis. We suggest that the stochastic pattern of variegation in the mutant may be due to an interplay of factors that regulate var2 gene expression and factors that mediate rates of cell and plastid division. Plastids with a critical threshold of the partially functional var2 protein are green, while plastids containing less than the threshold of var2 activity are white.

FISH mapping and identification of canine chromosomes

Abstract: The karyotype of the domestic dog (Canis familiaris) is widely accepted as one of the most difficult mammalian karyotypes to work with. The dog has a total of 78 chromosomes; all 76 autosomes are acrocentric in morphology and show only a gradual decrease in length. Standardization of the canine karyotype has been performed in two stages. The first stage dealt only with chromosomes 1-21 which can be readily identified by conventional G-banding techniques. The remaining 17 autosomal pairs have proven to be very difficult to reliably identify by banding alone. To facilitate the identification of all canine chromosomes, chromosome-specific paint probes have been produced by DOP-PCR from flow-sorted dog chromosomes. Each paint probe has been used for FISH to identify the corresponding chromosome(s), allowing precise identification of all 78 canine chromosomes. The identification of the undesignated 17 autosomal pairs has been agreed upon by the standardization committee during the second stage of their role. Cosmid clones containing microsatellite markers may now be conclusively assigned to their chromosomal origin by simultaneous dual-color FISH with the corresponding paint probe. In this way a collection of chromosome-specific cosmid clones is being constructed, comprising at least one marker per chromosome, which will allow anchoring of existing and future linkage groups to the physical map.

Inheritance and linkage relationships of days to flower and morphological loci in lentil (Lens culinaris Medikus subsp. culinaris)

Abstract: Lentils from south Asia differ markedly in days to flower and several other traits from lentils in other major lentil producing areas of the world such as west Asia. Single-gene inheritance and a polygenic system were observed to control days to flower in lentil (Lens culinaris Medikus subsp. culinaris). Early flowering was determined by a single recessive gene (sn). Early flowering transgressive segregants occurred in F2 populations due to the interaction of sn and minor genes for earliness. Pubescent peduncle (Pep) was inherited as a single gene dominant to glabrous peduncle (pep). Tendrilless leaf (tnl) was controlled by a single gene recessive to tendrilled leaf (Tnl). The Sn, Scp (seed coat pattern), and Pep loci were linked together in linkage group 5 and Tnl was linked with Gs (colored stem) in linkage group 1 of the lentil genome.

Inheritance and distribution of trichome phenotypes in Datura wrightii

Abstract: Glandular trichomes in plants often confer resistance to herbivorous insects The native plant species Datura wrightii (Solanaceae) is polymorphic with regard to trichome morphology Some mature plants are covered primarily with nonglandular trichomes, while others possess glandular trichomes that excrete a sticky exudate Both phenotypes were found in nearly all southern California plant populations surveyed The frequencies of glandular (sticky) and nonglandular (velvety) phenotypes, however, varied significantly among populations By employing reciprocal hybridization and backcross designs, we showed that trichome phenotype is inherited largely in a Mendelian fashion The allele coding for the sticky phenotype was dominant over that for the velvety phenotype The expression of the recessive gene was age dependent; velvety phenotypes produced glandular trichomes on their cotyledons and the first five true leaves Thereafter these plants produced nonglandular trichomes on all newer leaves We hypothesize that feeding by herbivorous insects and/or water stress may play a role in maintaining this polymorphism in natural plant populations

Unique aspects of cytoplasmic male sterility and fertility restoration in Brassica napus

Abstract: Two male sterile cytoplasms, nap and pol, are found in the oilseed rape species Brassica napus. As with many other forms of cytoplasmic male sterility (CMS), the mtDNA regions implicated in specifying the two forms of male sterility contain novel open reading frames (ORFs). Unlike other CMS-associated ORFs, however, a high level of sequence similarity extends over the entire length of the nap and pol CMS-associated ORFs. Moreover, in other plant species where more than one form of CMS is found, the nuclear genes that restore fertility to various male sterile cytoplasms represent distinct genes that map to different nuclear loci. The restorers for the nap and pol cytoplasms (Rfn and Rfp, respectively), however, represent different alleles or haplotypes of a single nuclear locus. Both alleles specify factors that influence mtRNA processing events, but the specific processing events conditioned by the two alleles are different, suggesting that the factors encoded by these genes recognize distinct RNA structural features. Finally, unlike other nuclear genes that affect mitochondrial gene expression, Rfn is capable of modifying the expression of multiple mtDNA regions, some of which are not associated with CMS. Findings made based on this observation are consistent with the view that new alleles of a restorer locus arise in response to natural selective pressures generated by the appearance of new male sterile cytoplasms.

Inheritance of 12 microsatellite loci in Oncorhynchus mykiss

Abstract: Four full-sib families of Oncorhynchus mykiss were used to study the inheritance of allelic variation at 12 microsatellite loci. The loci examined were previously characterized in six different species from the family Salmonidae. Of the 48 genotypic ratios observed (12 loci 3 4 crosses), disomic segregation of codominant autosomal alleles was established in 24 of 31 informative tests. The seven tests that did not conform to Mendelian ratios can be explained by the presence of null alleles (Onem14 and Omy77) and a locus (Onem1) that may be tandemly duplicated. Three significant pairwise linkage associations were observed between Onem1 and Omy207, Ssa85 and Onem11, and the two loci amplified by Onem1 primers, indicating these loci are not assorting independently. The presence of unexpected heteroduplex structures in Onem11 electropherograms in one cross prompted the sequencing of similar microsatellite electromorphs. Sequence differences revealed size homoplasy, that is, the electromorphs were identical in state but they were not identical by descent. These results demonstrate the need to conduct comprehensive species-specific inheritance studies for microsatellite loci used in population genetic or kinship analyses. Discovery of these four attributes by examining a small number of loci in four families suggests that they are common across microsatellite loci overall.

Phenotypic and genetic architecture of juvenile morphometry in chinook salmon

Abstract: Juvenile morphology can affect fitness of salmonids in nature, but the genetic basis for morphometry in salmonids is poorly understood. We mated chinook salmon in a half-sib/full-sib breeding design to determine the genetic and environmental components of morphometric variation. We characterized body size and shape in 20 progeny from each of 95 full-sib families by digitizing 30 landmarks on lateral, dorsal, and ventral images of the body form, and estimated genetic and environmental components of variance for 12 truss elements constructed from the landmarks. We then conducted principal component analyses of the phenotypic, genetic, and environmental covariance matrices for these elements. Most (83%) of the phenotypic variation in morphometry was expressed along axes of allometry, shape change during smoltification, and a three-dimensional body shape contrast (head width versus lateral profile depth). All morphometric traits showed substantial additive genetic variation and were highly correlated genetically as well as phenotypically. Principal components of genetic variation in morphometry resembled the phenotypic principal components. The analyses also detected strong environmental effects on body shape and indicated two distinct morphometric types arising from maternal or environmental sources. The results provide evidence for genetic coordination of body size and shape, which would be expected if these characters are tightly coupled developmentally.

A QTL for the degree of spotting in cattle shows synteny with the KIT locus on chromosome 6

Abstract: The proportion of unpigmented coat on the trunk was determined from photographs of 38 German Simmental and 627 German Holstein bulls distributed over three generations. All 665 animals were members of 18 Holstein and 3 Simmental half-sib families. A Bayesian estimation of heritability yielded a posterior mean of 0.88 and a standard error of 0.08. A quantitative trait loci (QTL) scan over all chromosomes covered by 229 microsatellite marker loci (2926 cM) was performed by fitting a multiple marker regression model to 625 observations from the youngest generation in 18 families. On chromosome 6 a QTL for the proportion of white coat with large effects (experiment-wise error probability < .0001) was found and a less important one on chromosome 3 (chromosome-wise error probability < .009). Chromosome 6 is known to harbor the KIT locus (receptor tyrosinase kinase), which is associated with various depigmentation phenotypes in mice, humans, and pigs. Similarity of phenotypic KIT effects in other species and synteny with the reported QTL suggest that KIT is a serious candidate gene for the degree of spotting in cattle. The results are also discussed with respect to resistance to solar radiation, heat stress, and photosensitization.

Inter- and intragenomic chromosome pairing in haploids of durum wheat

Abstract: To assess inter- and intragenomic chromosome pairing in durum wheat (Triticum turgidum L.), chromosome pairing and chiasma frequency were studied in durum haploids (2n 5 2x 5 14; AB genomes) with the Ph1 allele, haploids with the ph1c allele, and substitution haploids with chromosome 5B replaced by 5D. The Ph1haploids extracted from seven durum cultivars had little pairing; on the average only 3.1% of the chromosome complement was paired with 0.23 chiasma per pollen mother cell (PMC). Variation in haploid chromosome pairing frequency was observed among the seven genotypes. Chromosomes of the A and B genomes in the ph1c-haploids showed increased pairing, with 38.6% of the complement paired and 3.0 chiasmata per cell. The potential of intergenomic pairing was more fully realized in the substitution haploids, which had 51.3% of the complement paired with a chiasma frequency of 4.1 per cell. Fluorescent GISH (genomic in situ hybridization) analysis of PMCs revealed that most of the pairing was intergenomic, that is, between the chromosomes of the A and B genomes. Up to six intergenomic bivalents were observed. Ring bivalents were common; a few showed interlocking. A low frequency of intragenomic pairing within the A genome and within the B genome was observed; the GISH analysis confirmed that this was not caused by intergenomic translocations. Bivalents within the A genome likely involved chromosomes 4A and 7A, and were more frequent than those within the B genome. Chromosome pairing and chiasma frequencies in the 5D(5B) substitution haploids were similar to those in amphihaploids obtained by hybridization between the putative progenitors of durum wheat. It is obvious that the homoeologous pairing control mechanism present in 5B exercises almost total pairing control that exists in durum wheat and that the effect of other pairing control genes, if any, is insignificant. Moreover, the A and B genomes have undergone little structural modification since the evolution of durum wheat several thousand years ago. Durum haploids, therefore, offer excellent tools for studying genomic relationships in durum wheat.

Microsatellite variation in the Australian dingo

Abstract: The dingo is thought to have arrived in Australia from Asia about 5,000 years ago. It is currently in danger because of interbreeding with domestic dogs. Several morphological, behavioral, and reproductive characteristics distinguish dingoes from domestic dog. Skull morphometrics are currently used to try to classify wild canids as pure dingo, dog, or hybrid. Molecular techniques based on diagnostic DNA differences between dogs and dingoes would make a much more reliable and practical test. A small number of markers (about 10) would allow detection of animals with domestic dog in their ancestry several generations back. We have typed 16 dingoes and 16 dogs of mixed breed for 14 microsatellites. The amount of variation in the Australian dingo is much less than in domestic dogs. The size distributions of microsatellites in the two groups usually overlap. The number of alleles in the dingo is much smaller in all cases. One dinucleotide repeat locus shows a size difference of 1 bp in allele classes between dog and dingo. This locus may be diagnostic for dog or dingo ancestry. The differences in distributions of alleles at other loci can also be used to classify animals using a likelihood method.

An outcrossed canine pedigree for linkage analysis of hip dysplasia

Abstract: Canine hip dysplasia (CHD) is a prevalent, debilitating, polygenic disease characterized by hip subluxation and laxity which results in osteoarthritis. We are developing an informative pedigree for linkage analysis of CHD. The seven greyhound founders had excellent hip conformation with high dorsolateral subluxation scores (percentage of femoral head covered by the dorsal acetabulum in a weight-bearing position) of 66 +/- 4% (mean +/- SD averaged over both hips) and low hip distraction (laxity) indices of 0.14 +/- 0.08. Nine greyhounds bred on site had radiographic evidence of ossification in the capital femoral chondroepiphysis at 7.7 +/- 0.9 days of age. At 8 months of age they had a mean distraction index of 0.24 +/- 0.08 and dorsolateral subluxation score of 76 +/- 1%. Of the four dysplastic Labrador retriever founders, three had mean age at onset of capital femoral chondroeplphyseal ossification of 20 +/- 7 days of age n = 3) and a mean distraction index of 0.46 +/- 0.1 accompanied by hip osteoarthritis. Thirty-four F1s had mean onset of capital femoral ossification (10.7 +/- 4.0 days of age) and mean dorsolateral subluxation scores (61 +/- 12%) similar to the greyhound founders, but distraction indices (0.42 +/- 0.2) more similar to the Labrador retriever founders. One F1 had CHD radiographically but none of 20 F1s had osteoarthritis at necropsy at 10 months of age. These data suggested that maximum passive laxity (as measured by the distraction index) and normal osseous conformation (as indicated by a high dorsolateral subluxation score) were both dominant traits and were controlled by separate quantitative trait loci (QTL). Forty-three back-crosses between F1s with the highest hip laxity and greyhound founders had mean onset of capital femoral ossification at 9.9 +/- 2.6 days of age. Of 10 dogs in the backcross generation that have reached 8 months of age, 2 had palpable subluxation without marked CHD radiographically. The mean distraction index of these dogs was 0.36 +/- 0.16 and the dorsolateral subluxation score was 65 +/- 5%. Although dogs in the backcross generation that were three-quarter greyhound had a broad range of hip laxity, a protective effect of the greyhound QTLs for good osseous conformation has mitigated thus far against subluxation and CHD.

Globoid cell leukodystrophy in Cairn and West Highland white terriers

Abstract: Krabbe disease or globoid cell leukodystrophy (GLD) is an autosomal recessive disorder resulting from the defective lysosomal hydrolysis of specific galactolipids found primarily in myelin. This leads to severe neurological symptoms including seizures, hypotonia, blindness, and death, usually before 2 years of age in human patients. In addition to human patients, several animals, including dog, mouse, and monkey, have the same disease caused by a deficiency of galactocerebrosidase (GALC) activity. In this article we describe studies in cairn and West Highland white terriers (WHWT) affected with GLD. Through a screening test based on the molecular defect found in these breeds, over 50 cairn terrier carriers have been identified and a colony of five carrier dogs has been established. Affected dogs from this colony plus an affected WHWT were available for study. An affected WHWT was evaluated by magnetic resonance imaging at 6 and 11 months of age and pronounced changes in the T-2 weighted fast spin-echo images were found. Biochemical and pathological evaluation of the same dog after euthanasia at 12 months of age showed a large accumulation of psychosine in the brain and white matter filled with globoid cells. Some comparisons were made to younger affected and carrier dogs. Studies have shown successful transduction of cultured skin fibroblasts from an affected dog and normal canine bone marrow using a retroviral vector containing the human GALC cDNA. Successful treatment of this canine model will lead to studies in some humans with GLD.

Markers within the regulatory region of the growth hormone receptor gene and their association with milk-related traits in Holsteins

Abstract: We studied sequence variations in the regulatory region of the bovine growth hormone receptor gene. A polymerase chain reaction (PCR)-based method for detecting AluI, AccI, and StuI restriction fragment length polymorphisms (RFLPs) in the 5' flanking region of the bovine growth hormone receptor gene was developed and tested for association with milk-related traits in Holstein bulls. Allele frequencies of the polymorphisms in two groups of Holstein progeny-tested bulls born from 1950 to 1970 and in the 1980s, respectively, were estimated. The allele frequency of the AluI(-) allele was 0.63 and 0.42 in the bulls from 1950 to 1970 and in the 1980s, respectively. The frequency of the StuI(-) allele was 0.14 and 0.07 in the two respective bull groups. Allele frequency for AccI(-) allele was about 0.22 in both bull groups. The differences in allele frequencies for the AluI polymorphism in the two bull groups were significantly different (P < or = .005). The AluI(+/+) bulls had a higher estimated breeding value (EBV) for fat (P < or = .016) than AluI(-/-) bulls. The average effect of allele substitution for the AluI polymorphism was +/- 8 for fat EBV. The AluI polymorphism could be further evaluated for use in marker-assisted selection in dairy cattle.

Duplication of the Brassica oleracea APETALA1 floral homeotic gene and the evolution of domesticated cauliflower.

Abstract: Development of the cauliflower phenotype in Arabidopsis thaliana requires mutations at both the CAULIFLOWER and APETALA1 loci. BoAP1 is the Brassica oleracea orthologue to the Arabidopsis AP1 gene, and is present in two copies in Brassica genomes. The BoAP1-A gene appears to encode a full-length protein, but BoAP1-B alleles in B. oleracea contain insertions that lead to premature translation termination. The BoAP1-B allele found in most B. oleracea subspecies, including B. oleracea ssp. botrytis (domesticated cauliflower) contains a 9 bp insertion in exon 4. This insertion leads to the formation of an in-frame translation termination codon, and these alleles can encode a protein that is truncated at the K domain of this MADS-box transcriptional activator. The allele in B. oleracea ssp. oleracea (wild cabbage) lacks this insertion and instead contains a downstream 4 bp frameshift mutation resulting in the formation of a nonsense mutation. The structure of the BoAP1-B alleles suggests that they are impaired in their ability to perform their floral meristem identity function. These mutations, in conjunction with mutations at the BoCAULIFLOWER (BoCAL) locus, may be associated with the evolution of domesticated cauliflower.

Viable androgenetic YY genotypes of common carp (Cyprinus carpio L.)

Abstract: The present invention discloses a polishing pad that can facilitate process stability, extend length of use, and mitigate process non-uniformity and process induced defects for chemical mechanical planarization processes. The polishing pad of the present invention is a composite of a top pad and a sealed sub-pad. The sealed sub-pad has a sealing mechanism that mitigates liquid penetration into the sub-pad thereby maintaining a substantially uniform compressibility of the sub-pad and the polishing pad and extending a useable life of the polishing pad.

A review of canine inherited bleeding disorders: biochemical and molecular strategies for disease characterization and carrier detection

Abstract: Many different inherited bleeding disorders have been identified in dogs, defined on the basis of quantitative, functional, or structural defects in specific hemostatic proteins or pathways. Most of these disorders are caused by single-gene defects and biochemical assays provide an accurate measure of disease phenotype. Phenotypic disease classifications, however, are often genetically heterogeneous. Protein-based carrier detection assays are fast, inexpensive, and do not require specific identification of causative mutations. The limitations of these tests arise from variable "overlap" regions between carrier and clear dogs, influencing positive and negative predictive values of carrier detection tests within breed populations. Molecular diagnostic techniques enhance the accuracy of carrier detection, providing their clinical application takes into account the molecular heterogeneity underlying naturally occurring hemostatic defects in dogs.