Multifactorial inheritance of common white markings in the Arabian horse

The results of a previous study were compatible with the hypothesis that common white facial markings in the Arabian horse have a multifactorial mode of inheritance. I expanded that study to (1) include the legs and therefore obtain insight into the heritability of common white markings in all peripheral regions (face and legs) of the Arabian horse and (2) investigate the influence of sex and the genotypes that produce the bay and chestnut phenotypes on the variation in common white markings. Both studies were based on computerized data obtained from the Arabian Horse Registry of America, Inc. Each leg of a horse was scored from 0 to 5 depending on the amount of whiteness present, and the four leg scores were added to obtain the total leg score for each horse. The facial region was divided into five areas, and each horse was given a score from 0 to 5 according to the number of areas with whiteness. Sire families were analyzed in which each sire family consisted of a sire, his foals, and the dams of those foals. There was a correlation between white facial scores and white leg scores, suggesting that both types of white markings are influenced by the same genetic mechanism. Sire-foal and dam-foal regression analyses were compatible with the hypothesis that common white leg markings also show multifactorial inheritance. Although the results support the model that additively acting genes (polygenes) influence the presence and extent of common white markings, the results also show that males are slightly more marked than are females and that chestnut horses are more heavily marked than are bay horses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Multifactorial inheritance of white facial markings in the Arabian horse

The hypothesis was tested that white facial markings in the Arabian horse show multifactorial inheritance. The hypothesis assumes that (1) alleles at different loci acting in a cumulative manner influence the variation in white facial markings, (2) the amount of whiteness is correlated with the number of genes, and (3) interacting nongenetic factors influence the variation. The study was based on computerized data obtained from the Arabian Horse Registry of America, Inc. The facial region was divided into five areas, and each horse was given a score according to the number of areas with a white marking. Twenty-two sire families were analyzed. Each sire family consisted of a sire, his foals, and the dams of those foals. The results of the investigation, including dam-foal and sire-foal regression analyses, were totally compatible with the hypothesis. A heritability study suggested that about two-thirds of the phenotypic variation in white facial markings among Arabian horses is attributable to genetic differences.     

Consanguinity in multifactorial inheritance. Application to data on congenital glaucoma

The increase of parental consanguinity in multifactorial inheritance is evaluated by calculating the expected incidence of affected children whose parents are first cousins, using several values, namely for condition frequency and heritability of liability. This increase is compared to the expected increase in recessive inheritance, when one or more loci are involved. The method is illustrated by examples of recessive and multifactorial conditions and applied, as a test of discrimination between different modes of inheritance, to data on congenital glaucoma.     

Autosomal recessive inheritance of congenital goiter in Afrikander cattle

Congenital goiter was reported in a number of herds of Afrikander cattle in the 1950's. Some affected animals were assembled and maintained as a closed herd. Although considerable biochemical research into the nature of the disease has been conducted, no definitive report has described the mode of inheritance of the defect. This paper presents the results of breeding studies that indicate the defect is inherited as an autosomal recessive. Southern blot analysis of the thyroglobulin gene confirms this finding. In addition, serum levels of TSH (thyroid stimulating hormone, thyrotropin), T3 (3,4,3'-tri-iodothyronine), T4 (thyroxine), rT3 (3,3',5'-tri-iodothyronine), and DIT (diiodotyrosine) of goitrous animals are compared with normal animals.     

Nud1p, the yeast homolog of Centriolin, regulates spindle pole body inheritance in meiosis

Nud1p, a protein homologous to the mammalian centrosome and midbody component Centriolin, is a component of the budding yeast spindle pole body (SPB), with roles in anchorage of microtubules and regulation of the mitotic exit network during vegetative growth. Here we analyze the function of Nud1p during yeast meiosis. We find that a nud1-2 temperature-sensitive mutant has two meiosis-related defects that reflect genetically distinct functions of Nud1p. First, the mutation affects spore formation due to its late function during spore maturation. Second, and most important, the mutant loses its ability to distinguish between the ages of the four spindle pole bodies, which normally determine which SPB would be preferentially included in the mature spores. This affects the regulation of genome inheritance in starved meiotic cells and leads to the formation of random dyads instead of non-sister dyads under these conditions. Both functions of Nud1p are connected to the ability of Spc72p to bind to the outer plaque and half-bridge (via Kar1p) of the SPB.     

Identification of a codominant scar marker linked to the seedlessness character in grapevine

 The variety Vitis vinifera cv Sultanine presents a type of seedlessness in which fertilization occurs but seeds subsequently fail to develop. It has been suggested that this trait might be controlled by three complementary recessive genes regulated by a dominant gene named I. Bulk segregant analysis was used to search for random amplified polymorphic DNA (RAPD) markers linked to the I gene in progeny obtained by crossing two partially seedless genotypes. One hundred and forty decamer primers were screened using bulks obtained by pooling the DNA of extreme individuals from the phenotypic distribution. We identified two RAPD markers which appeared tightly linked to I (at 0.7 and 3.5 cM respectively). The closest marker was used to develop a codominant SCAR (sequence characterized amplified region), named SCC8. This latter marker appeared of great value either to exclude from the progeny potentially seeded individuals or to select for seedless individuals. Indeed, all the seeded individuals of the progeny were found to be homozygous scc8 ^-/scc8 ^-, and all the individuals homozygous SCC8 ⁺/SCC8 ⁺ were seedless. Moreover, this marker was successfully applied to other natural seedless varieties where codominance persisted. SCC8 was also used to dissect more precisely the genetics of seedlessness. ANOVA analysis indicated that this SCAR marker accounted for at least 64.9% of the phenotypic variation of the seed’s fresh weight and for at least 78.7% of the phenotypic variation of the seed’s dry matter. These results confirmed the presence of a major gene, and also the existence of other complementary recessive genes, controlling the expression of seedlessness. Received: 29 July 1997 / Accepted: 16 March 1998     

The cloned guinea pig neuropeptide Y receptor Y1 conforms to other mammalian Y1 receptors.

We have cloned the guinea pig neuropeptide Y (NPY) Y1 receptor and found it to be 92-93% identical to other cloned mammalian Y1 receptors. Porcine NPY and peptide YY (PYY) displayed affinities of 43 pM and 48 pM, respectively. NPY2-36 and NPY3-36 had 6- and 46-fold lower affinity, respectively, than intact NPY. Functional coupling was measured by using a microphysiometer. Human NPY and PYY were equipotent in causing extracellular acidification with EC50 values of 0.59 nM and 0.69 nM, respectively, whereas NPY2-36 and NPY3-36 were about 15-fold and 500-fold less potent, respectively, than NPY. The present study shows that the cloned guinea pig Y1 receptor is very similar to its orthologues in other mammals, both with respect to sequence and pharmacology. Thus, results from previous studies on guinea pig NPY receptors might imply the existence of an additional Y1-like receptor sensitive to B1BP3226.     

Phylogenetic affinity of a Giardia lamblia cysteine desulfurase conforms to canonical pattern of mitochondrial ancestry

Among a few potential archezoan groups, only the Metamonada (diplomonads, retortamonads, and oxymonads) still retain the status of amitochondriate protists that diverged before the acquisition or retention of mitochondria. Indeed, finding that diplomonad genomes harbor a gene encoding a mitochondrial type chaperonin 60, the most compelling evidence for their secondarily amitochondriate nature, may be interpreted as an acquisition of this important general chaperone during some transient alpha-proteobacterial endosymbiosis. Recently published data on the cysteine desulfurase IscS demonstrated an alpha-proteobacterial origin of mitochondrial enzymes including a diplomonad Giardia lamblia homolog. An extended phylogenetic analysis of IscS is reported here that revealed a full canonical pattern of mitochondrial ancestry for the giardial enzyme. The above canonical pattern, a sister group relationship of mitochondria and rickettsiae exclusive of free-living alpha-proteobacteria, was robustly confirmed by a comprehensive analysis of Cob and Cox1 subunits of the respiratory chain encoded by resident mitochondrial genes. Given that Fe-S cluster assembly involving IscS represents an essential mitochondrial function, these data strongly suggest that diplomonads once harbored bona fide mitochondria.     

Development of a codominant CAPS marker linked to PRSV-P resistance in highland papaya

Development of resistant papaya varieties is widely considered the best strategy for long-term control of the papaya ringspot virus type P (PRSV-P). Several species of “highland papaya” from the related genus Vasconcellea exhibit complete resistance to PRSV-P, and present a valuable source of resistance genes with potential for application in Carica papaya. The objectives of this study were two fold; to identify molecular markers linked to a previously characterised PRSV-P resistance gene in V. cundinamarcensis (psrv-1), and to develop codominant marker based strategies for reliable selection of PRSV-P resistant genotypes. Using a bulked segregant analysis approach, dominant randomly amplified DNA fingerprint (RAF) markers linked to prsv-1 were revealed in the resistant DNA bulk, which comprised F2 progeny from a V. parviflora (susceptible) × V. cundinamarcensis (resistant) interspecific cross. One marker, Opk4_1r, mapped adjacent to the prsv-1 locus at 5.4 cM, while a second, Opa11_5r, collocated with it. Sequence characterisation of the Opk4_1r marker permitted its conversion into a codominant CAPS marker (PsiIk4), diagnostic for the resistant genotype based on digestion with the restriction endonuclease PsiI. This marker mapped within 2 cM of the prsv-1 locus. Psilk4 was shown to correctly identify resistant genotypes 99% of the time when applied to interspecific F2 progeny segregating for the resistant character, and has potential for application in breeding programs aimed to deliver the PRSV-P resistance gene from V. cundinamarcensis into C. papaya.Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

A codominant molecular marker in linkage disequilibrium with a restorer-of-fertility gene (Ms) and its application in reevaluation of inheritance of fertility restoration in onions

To reveal the linkage relationship between the Ms locus, a restorer-of-fertility gene for cytoplasmic male-sterility (CMS) caused by CMS-S cytoplasm in onion (Allium cepa L.) and previously reported molecular markers linked to the Ms locus, 11 recombinants selected from 4,273 segregating plants originating from the cross between male-sterile maternal and male-fertile paternal lines were analyzed. Results showed that genotypes of a codominant marker, jnurf12, were perfectly matched with the male-fertility phenotypes in all recombinants, but that this marker was not applicable in diverse breeding lines due to multiple band patterns. For the development of more reliable markers, a 12-bp indel was identified from the sequences which were obtained by genome walking, and was used to develop a simple PCR marker which was designated jnurf13. When 104 diverse breeding lines containing CMS-S cytoplasm were analyzed with the jnurf13 marker, male-fertility phenotypes of all breeding lines were perfectly matched with marker genotypes. To our surprise, phenotypes of 153 breeding lines containing CMS-T-like cytoplasm were also matched with genotypes of the jnurf13 marker which was linked to the Ms locus for the CMS-S system. Furthermore, phenotypes of four F₂ populations containing CMS-T-like cytoplasm co-segregated perfectly with jnurf13 genotypes. Allelic segregation distortion was detected in two F₂ populations using the jnurf13 maker. The results of this study were in conflict with a previous model for inheritance of fertility restoration in the CMS-T system. Therefore, we proposed a new model based on the data analyzed with the jnurf13 marker, which was in linkage disequilibrium with restorer-of-fertility genes for both CMS systems.     

Permeability of acetic acid across gel and liquid-crystalline lipid bilayers conforms to free-surface-area theory.

Solubility-diffusion theory, which treats the lipid bilayer membrane as a bulk lipid solvent into which permeants must partition and diffuse across, fails to account for the effects of lipid bilayer chain order on the permeability coefficient of any given permeant. This study addresses the scaling factor that must be applied to predictions from solubility-diffusion theory to correct for chain ordering. The effects of bilayer chemical composition, temperature, and phase structure on the permeability coefficient (Pm) of acetic acid were investigated in large unilamellar vesicles by a combined method of NMR line broadening and dynamic light scattering. Permeability values were obtained in distearoylphosphatidylcholine, dipalmitoylphosphatidylcholine, dimyristoylphosphatidylcholine, and dilauroylphosphatidylcholine bilayers, and their mixtures with cholesterol, at various temperatures both above and below the gel-->liquid-crystalline phase transition temperatures (Tm). A new scaling factor, the permeability decrement f, is introduced to account for the decrease in permeability coefficient from that predicted by solubility-diffusion theory owing to chain ordering in lipid bilayers. Values of f were obtained by division of the observed Pm by the permeability coefficient predicted from a bulk solubility-diffusion model. In liquid-crystalline phases, a strong correlation (r = 0.94) between f and the normalized surface density sigma was obtained: in f = 5.3 - 10.6 sigma. Activation energies (Ea) for the permeability of acetic acid decreased with decreasing phospholipid chain length and correlated with the sensitivity of chain ordering to temperature, [symbol: see text] sigma/[symbol: see text](1/T), as chain length was varied. Pm values decreased abruptly at temperatures below the main phase transition temperatures in pure dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine bilayers (30-60-fold) and below the pretransition in dipalmitoylphosphatidylcholine bilayers (8-fold), and the linear relationship between in f and sigma established for liquid-crystalline bilayers was no longer followed. However, in both gel and liquid-crystalline phases in f was found to exhibit an inverse correlation with free surface area (in f = -0.31 - 29.1/af, where af is the average free area (in square angstroms) per lipid molecule). Thus, the lipid bilayer permeability of acetic acid can be predicted from the relevant chain-packing properties in the bilayer (free surface area), regardless of whether chain ordering is varied by changes in temperature, lipid chain length, cholesterol concentration, or bilayer phase structure, provided that temperature effects on permeant dehydration and diffusion and the chain-length effects on bilayer barrier thickness are properly taken into account.     

Development and mapping of a codominant SCAR marker linked to the andromonoecious gene of melon

Monoecy is an important goal for melon breeding because of the agronomic advantages it provides to parental lines in that they do not require hand emasculation to develop monoecious F₁ hybrids, the latter producing fruits of higher quality. Monoecious phenotype is conferred by the dominant allele of the andromonoecious (a) gene, whereas recessive homozygous plants are andromonoecious. A bulked segregant analysis (BSA) approach performed in a set of 38 double-haploid lines has allowed us to identify an AFLP marker linked to the a gene at 3.3 cM. Following cloning and sequencing of the AFLP fragment, specific PCR primers were designed and used in the amplification of a codominant SCAR marker. Using a backcrossed mapping population of 530 plants, the SCAR marker could be mapped near the a locus (5.5 cM). Size difference between the two allelic SCAR fragments is 42 bp and might be due to a deletion/insertion. The SCAR marker is closest to the a gene identified to date, and can be useful in breeding programs, using marker-assisted selection procedures to screen for sexual types in melon.