Showing papers in "Journal of Heredity in 1990"

A Retrospective View of Corn Genetic Resources

Abstract: Corn genetic resources include wild relatives, races, open pollinated varieties, genetic and cytogenetic markers, synthetics, and elite inbreds. Popular modern hybrids contain one or more elite inbreds. Successful corn breeders use the best genetic resources available; elite inbreds are now the best genetic resource

A Series of FORTRAN Computer Programs for Estimating Plant Mating Systems

Abstract: loid, backcross, recombinant inbred, various testcross, F2, and F3 progeny in which the phenotypes of flanking molecular marker loci are used as independent variable values (Knapp et al 1990) The statistical models arising from these genetic models are nonlinear The parameters of these models are the means of quantitative trait locus genotypes and recombination frequencies between marker and quantitative trait loci We are distributing SAS (1987) PROC NLIN programs for estimating the parameters of these models using maximum-likelihood methods (PROC NLIN is the SAS [1987] procedure for estimating the parameters of nonlinear models) The Gauss-Newton algorithm (Gallant 1987) and ordinary or generalized least squares methods are used in our programs Maximum-likelihood estimates of the parameters are output In addition, we are distributing PROC IML, PROC REG, and PROC NLIN programs (SAS 1985, 1987), which test hypotheses about gene effects and recombination frequencies using Wald statistics or log-likelihood ratios (Gallant 1987) The model and derivative source code from our programs, which are specific to the genetic and statistical models, can be used in C or FORTRAN implementations of Marquardt or GaussNewton nonlinear least-squares algorithms (Press et al 1986, 1988)

Fat (fat) and tubby (tub): two autosomal recessive mutations causing obesity syndromes in the mouse

Abstract: This report describes the development of obesity syndromes in mice caused by two autosomal recessive mutations, fat (fat), located on chromosome 8, and tubby (tub), located on chromosome 7. Both mutations cause slowly developing but ultimately severe obesity conditions. Although hyperinsulinemia, hyperactivity of the beta cell of the islets of Langerhans, and beta-cell degranulation are consistent features, these obesity syndromes do not progress to severe diabetes. The many different single-gene mutations in the mouse that produce obesity-diabetes syndromes of varying degrees of severity make the mutant mouse a powerful tool for analyzing the number and nature of the primary defects than can cause obesity states.

Physical Mapping of the 5S rRNA Multigene Family in Common Wheat

Abstract: In situ hybridization in conjunction with deletion mapping was used to physically map the 5S rRNA multigene family in Triticum aestivum L. cv. «Chinese Spring». Twelve 5S rRNA loci were mapped on chromosomes of homoeologous group 1 (arms 1AS, 1BS, and 1DS) and group 5 (arms 5AS, 5BS, and 5DS)

Conservation Genetics of Pacific Salmon. II. Effective Population Size and the Rate of Loss of Genetic Variability

Abstract: A simulation model for genetic change in Pacific salmon (Oncorhynchus spp.) populations is extended to examine the loss of genetic variability

Conservation Genetics of Pacific Salmon. III. Estimating Effective Population Size

Abstract: The temporal method for estimating the effective population number from the standardized variance of allele frequency change (F^) is evaluated for a model incorporating the unusual life history features of Pacific salmon (Oncorhynchus spp.). Computer simulations were used to establish the relationship between F^ and N b , the effective number of breeders per year

Evolution of the Mojavensis Cluster of Cactophilic Drosophila with Descriptions of Two New Species

Abstract: The mojavensis cluster of the repleta species group of Drosophila (Drosophilidae: Diptera) consists of three species. One is newly described as D. navojoa. A second species, described here as D. arizonae, replaces D. arizonensis, which has become a junior subjective synonym for D. mojavensis, the third species in the cluster. A phylogeny of the three species is presented, based on chromosomal inversions, morphology, and the ability to produce hybrids. Breakage points are assigned for all inversions, and male genitalia are figured; 186 crosses were made from 225 possible combinations among 15 geographic strains from the southwestern United States, Mexico, and Guatemala. It is confirmed that D. mojavensis and D. arizonae are very closely related and shown that D. navojoa is more distantly related in regard to all criteria. This relationship is supported by the geographical positions of the ancestral gene sequences in each species, which show a sequential northwest movement (D. navojoa----D. arizonae----D. mojavensis) from southern Mexico to southern California and northern Arizona. The relationship is also supported by the fact that D. navojoa breeds in Opuntia cactus, an ancestral behavior, whereas the other two species breed chiefly in Stenocereus cacti, a derived behavior. The possible role of this host plant shift in speciation is discussed.

The Genetics of Host-Pathogen Coevolution: Implications for Genetic Resource Conservation

Abstract: The results of long-term studies of coevolution in the Hordeum vulgare-Rhynchosporium secalis pathosystem are summarized. The genetic systems of barley (host) and R. secalis (pathogen) are complementary: Gene-for-gene interactions among loci affect many traits, leading to self-regulating adjustements over generations between host and pathogen populations

Heritability of Brain Size and Surface Features in Rhesus Macaques (Macaca mulatta)

Abstract: The extent of heritability for overall brain size and regional cortical surface features such as sulcus lengths is important for demonstrating a genetic component to the observed phenotypic differences among individuals and for evaluating the potential for evolutionary change in response to selection. Although the genetics of brain size has been extensively considered, the detailed morphology of the cortical surface has not previously been subjected to genetic analysis. We estimated the heritability of brain size and cortical sulcus lengths using 438 endocranial casts taken from skeletons of rhesus macaques (Macaca mulatta) from the Cayo Santiago population. Estimates were obtained both by mother-offspring regression and symmetric-differences-squared (SDS) methods. Brain size, measured as cranial capacity, was highly and significantly heritable in this population, confirming results of previous studies with laboratory mice. Overall, cortical sulcus lengths were also heritable, with 35% of the sulci significantly heritable at the 5% level in the mother-offspring analysis. The average mother-offspring heritability estimate, 0.31, was the same as the average heritability obtained previously from a series of 56 cranial metric characters. The SDS analyses generally corresponded to the findings based on mother-offspring regressions, although the significance test appeared more conservative. Both gross and detailed morphology of the brain are heritable.

Inbreeding Depression in Insular and Central Populations of Peromyscus Mice

Abstract: We tested the hypothesis that small, isolated populations would show less depression in fitness when inbred than would large, central populations. Laboratory stocks of Peromyscus leucopus and P. polionotus were established from insular, peninsular, and central populations. The isolated populations had one-third to one-half the genic diversity of central populations. Responses to inbreeding were highly varied: some populations had smaller litters, others experienced higher mortality, some showed slower growth rates, and one displayed no measurable effects when inbred. These results suggest that inbreeding depression is controlled by a small number of genes and that the size of the genetic load depends on which alleles are present in the founders of a population. The severity of fitness depression in inbred litters did not correlate with initial genic diversity of the stocks nor, therefore, with the size of the wild populations. Fitness measures appeared linearly related to the inbreeding coefficient of the liters, with no diminution of deleterious effects through subsequent generations of inbreeding. Thus overdominance of fitness traits probably contributed as much to the genetic load as did deleterious recessive alleles. The inbreeding level of the dam negatively affected the size, growth, and survival of litters only in genetically diverse populations, indicating that the load of recessive alleles negatively impacting maternal care may have been reduced by selection in the more peripheral populations during past bottlenecks.

Evolution of the Avocados as Revealed by DNA Restriction Fragment Variation

Abstract: Individuals representing the genus Persea, subgenus Persea were assayed for restriction fragment length polymorphisms in their chloroplast genome, nuclear ribosomal DNA, and the genes coding for the enzyme cellulase

Genetic and Germ Plasm Stocks Worth Conserving

Abstract: The relative costs and benefits of genetic stock collections and germ plasm collections are discussed. The status of national and international collections is compared with the needs of plant breeders and geneticists

Isozyme Variability in Four Diploid Stone Fruits Compared with Other Woody Perennial Plants

Abstract: The level of isozyme variability at 12 loci in peach apricot, almond, and plum was found to be related to their mating behavior and germ plasm base

Inheritance and Linkage of Isozyme Coding Genes in Chickpea

Abstract: Genetics of 16 isozymes was determined in chickpea (Cicer L.) based on F2 segregation in interspecific crosses of Cicer arietinum L. with C. reticulatum   

Genetics of Seed Coat Color and Pattern in Lentil

Abstract: Lentil [Lens culinaris ssp. culinaris (Medik.) Williams] is a major grain legume (pulse) crop in North America. Various markets demand specific seed coat colors and/or patterns. We attempted to determine the mode of inheritance of seed coat color and pattern in the lentil. Inheritance studies involving crosses between parental lines with various seed coat colors and patterns indicated that seed coat color is determined by two independent loci. The dominant allele at one locus (Ggc) determines gray seed coat color, and the dominant allele at the second locus (Tgc) determines tan seed coat color. The two dominant alleles (Ggc Tgc) interact to produce a brown seed coat, whereas the double recessive (ggc tgc) is green. Seed coat pattern is determined by a series of five alleles at another locus. Marbled-1 (Scp(m1)) is dominant to marbled-2 (Scp(m2)), spotted (Scp(s)), dotted (Scp(d)), and absent (scp). Scp(m2) is dominant to Scp(s), Scp(d), and scp. Scp(s) and Scp(d) are codominant alleles, both of which are dominant to scp

Molecular Genetic Divergence of Orang Utan (Pongo pygmaeus) Subspecies Based on Isozyme and Two-Dimensional Gel Electrophoresis

Abstract: The orang utan (Pongo pygmaeus), as currently recognized, includes two geographically separated subspecies: Pongo pygmaeus pygmaeus, which resides on Borneo, and P. p. abelii, which inhabits Sumatra. At present, there is no known route of gene flow between the two populations except through captive individuals which have been released back into the wild over the last several decades. The two subspecies are differentiated by morphological and behavioral characters, and they can be distinguished by a subspecies specific pericentric chromosomal inversion. Nei-genetic distances were estimated between orang utan subspecies, gorilla, chimpanzee and humans using 44 isozyme loci and using 458 soluble fibroblast proteins which were resolved by two-dimensional gel electrophoresis. Phenetic analysis of both data sets supports the following conclusions: the orang utan subspecies distances are approximately 10 times closer to each other than they are to the African apes, and the orang utan subspecies are approximately as divergent as are the two chimpanzee species. Comparison of the genetic distances to genetic distance estimates done in the same laboratory under identical conditions reveals that the distance between Bornean vs. Sumatran orang utans is 5-10 times the distance measured between several pairs of subspecies including lions, cheetahs, and tigers. Near species level molecular genetic distances between orang utan subspecies would support the separate management of Bornean and Sumatran orang utans as evolutionary significant units (Ryder 1987). Evolutionary topologies were constructed from the distance data using both cladistic and phenetic methods. The majority of resulting trees affirmed previous molecular evolutionary studies that indicated that man and chimpanzee diverged from a common ancestor subsequent to the divergence of gorilla from the common ancestor.

Patchy Fur (Paf), a Semidominant X-Linked Gene Associated with a High Level of X-Y Nondisjunction in Male Mice

Abstract: Several X-linked mutations that have associated sex chromosomal nondisjunction have been identified in the mouse. We describe a new semidominant X-linked mutation called patchy fur (Paf) that produces an abnormal coat. It maps to the distal end of the murine X chromosome very near the XY pseudoautosomal region. The degree of severity in affected mice is hemizygous males greater than homozygous females greater than heterozygous females. An unusual feature of Paf is that either the mutation itself or an inseparable chromosomal abnormality causes delayed disjunction of the X and Y chromosomes at meiotic metaphase I, which in turn results in approximately 19% XO progeny and slightly less than 1% XXY progeny from Paf/Y males. The effect occurs only in male carriers and thus must extend into the proximal end of the XY pairing region.

Inheritance and Linkage Analysis of a New Fiber Mutant in Cotton

Abstract: A cotton plant, Gossypium hirsutum L., with abnormally short fibers was discovered in 1984 by Dr. G. A. Niles in a breeding nursery of the Texas Agricultural Experiment Station

Six actin gene subfamilies map to five chromosomes of Petunia hybrida.

Abstract: The Mitchell variety of Petunia hybrida possesses a superfamily of actin genes which contains between 100 and 200 members that can be divided into at least six highly divergent subfamilies. The segregation of restriction fragment length polymorphisms among 96 plants from two backcrosses between the Violet 23 and Red 51 Petunia varieties and the Violet 23 x Red 51 hybrid was examined using gene-specific probes from six Petunia actin gene subfamilies. These data were compared with the genotypes of each plant at 11 marker loci which are distributed among the seven chromosomes of Petunia and which determine flower, pollen, and isozyme phenotypes. From these analyses, members of these six actin gene subfamilies were mapped to five locations on five Petunia chromosomes: the PAc9, PAc1, PAc4, and PAc2 subfamilies are on chromosomes I, II, III, and VII respectively; the PAc3 and PAc7 subfamilies are tightly linked on chromosome IV. All members of the PAc4 subfamily cosegregated as a cluster of genes. These data are discussed regarding gene amplification in plants.

The Inheritance of the Leopard Complex of Spotting Patterns in Horses

Abstract: The leopard complex of white spotting patterns in horses consists of the leopard, few-spot leopard, blanket, blanket with spots, varnish roan (or marble), snowflake, frosted, speckled, and mottled patterns. Horses with any of these patterns can produce the other patterns when mated to nonpatterned horses. Twenty-two horses of the Welsh Pony, Noriker, Appaloosa, and Pony of the Americas breeds produced 270 foals in a distribution consistent with a single dominant allele being responsible for the patterns. The symbol for this dominant allele, Lp, is retained from previous work on the leopard pattern. Heterozygotes are less extensively marked than are homozygotes, but the two classes overlap. The differences in the patterns are related to varying degrees of expression of this allele.

Genetic Mapping of the Adh Locus in the Repleta Group of Drosophila by in situ Hybridization

Abstract: A biotinylated probe of the Adh (alcohol dehydrogenase) gene of Drosophila melanogaster was used for in situ hybridization on polytene chromosomes of D. mojavensis and D. buzzatii, two species of the repleta group of the genus Drosophila. Hybridization showed that the Adh gene maps at the G1a band of the third chromosome. This is in accordance with a previous result obtained through the use of interspecific hybrid asynapsis as a cytological marker and establishes the limits of the precision of this method.