Showing papers in "Journal of Heredity in 1988"
TL;DR: Selfing appears to promote the development and maintenance of adaptedness within populations and at the same time to facilitate the development of spatial differentiation by retarding gene flow between populations.
Abstract: The results of long-term studies of changes in adaptedness in a number of experimental populations of annual plants are summarized. Measurements made of quantitative traits showed that cumulative increases in reproductive capacity continued in these experimental populations for more than 50 generations. Highly significant allelic frequency changes also occurred for marker loci governing morphological variants, disease resistance, allozymes, and rDNA restriction fragments. Individual effects of the marker loci on quantitative traits were determined by extensive progeny testing of selfed families descended from single plants isolated from various generations of the experimental populations. Comparisons between homozygotes and heterozygotes of marker loci for quantitative trait expression revealed that all the marker loci studied had statistically significant additive effects on several to many quantitative traits; thus, each Mendelian locus, in addition to being a locus for its discrete descriptive effect, was also a locus for several quantitative traits. Consistent associations were found between superior reproductive capacity (e.g., larger numbers of kernels per plant) and the alleles of marker loci that increased in frequency over generations; no other quantitative traits measured were clearly and consistently associated with alleles that increased in frequency. Multilocus analyses based on canonical correlation, log linear, and cluster analysis procedures showed that highly significant associations developed in early generations among alleles of different loci in all the predominantly selfing populations studied. Dynamic changes featuring amalgamations of alleles into fewer clusters involving larger numbers of loci continued into the late generations. Patterns of ecogenetic differentiation that developed under predominant selfing were found to be fine-scaled overlays of environmental heterogeneity. The picture of evolutionary change that emerges is one in which the incorporation of increasing numbers of favorably interacting alleles into large synergistic complexes was accompanied in inbreeding populations by increases in adaptedness to the local environment and also by striking ecogenetic differentiation among local populations that occupy unlike habitats, including differentiation between cultivated plants and their wild progenitors. Selfing appears to promote the development and maintenance of adaptedness within populations and at the same time to facilitate the development of spatial differentiation by retarding gene flow between populations.(ABSTRACT TRUNCATED AT 400 WORDS)
273 citations
TL;DR: The exact provenance of GATCA sequences in present-day eukaryotes cannot be pinpointed, but evolutionary conservation and several modes of de novo generation are discussed.
Abstract: Simple tandemly organized GATCA sequences occurred in all eukaryotic genomes investigated. The amount and organization of individual GATCA sequences or derivatives thereof vary considerably in animal DNAs and can be assessed by simple but specific hybridization procedures with chemically pure oligonucleotide probes. In several animal species, including humans, GATCA sequences show extensive polymorphism, thus allowing individual-specific "DNA fingerprints." In selected rodents the sex-chromosomal organization of GATCA sequences is being studied extensively, revealing rapid evolutionary changes. In addition, insight can be expected into the sequences involved in obligatory meiotic crossing over between the X and Y chromosomes, into unequal crossing-over events, and into the linkage of GATCA elements to male-specific as well as to male-determining genes on the Y chromosome. The exact provenance of GATCA sequences in present-day eukaryotes cannot be pinpointed, but evolutionary conservation and several modes of de novo generation are discussed. Among these are unequal recombination, slipped strand mispairing, and other unspecified mechanisms. The latter include inherent properties that are responsible for the "selfish" or "ignorant" nature of simple repeats. Expression, if any, of GATCA sequences is critical to the overall significance of these ubiquitously interspersed simple repeats.
184 citations
TL;DR: Chromosomal structural changes-deletions and translocations-occurred in almost half the progeny of a monosomic addition line of common wheat, Triticum aestivum, which had a chromosome from Aegilops cylindrica, suggesting that when the A. cylindica chromosome was in the sporophytes, chromosome breakage was likely to occur in the gametophytes that lacked it, resulting in the production of offspring with chromosome structural changes.
Abstract: Chromosomal structural changes-deletions and translocations-occurred in almost half the progeny of a monosomic addition line of common wheat, Triticum aestivum (2n = 42, AABBDD), which had a chromosome from Aegilops cylindrica (2n = 28, CCDD). Most of the progeny with chromosomal structural changes lacked the A. cylindrica chromosome. Chromosome breaks were observed in various regions of all the wheat chromosomes and the A. cylindrica chromosome. Chromosome aberrations occurred far less frequently both in the self-progeny of the disomic addition plants and in the F1 monosomic addition plants derived from reciprocal crosses with normal common wheat. These findings suggest that when the A. cylindrica chromosome was in the sporophytes, chromosome breakage was likely to occur in the gametophytes that lacked it but that the gametophytes were still functional, resulting in the production of offspring with chromosomal structural changes.
162 citations
87 citations
TL;DR: Two mutant soybean lines with altered levels of palmitic acid in their oil were crossed and studied in F19, F21, and F31, generations and in the F2, generation of crosses to the cultivar "Century," which was the source of the mutations.
Abstract: Palmitic acid is the major saturated fatty acid in soybean seed oil. Two mutant soybean lines with altered levels of palmitic acid in their oil were crossed and studied in F19, F21, and F31, generations and in the F2, generation of crosses to the cultivar "Century," which was the source of the mutations. Frequency distributions for palmitic acid percentage displayed five peaks among F2, seeds from F1, plants and one, three, or five peaks among F2, seeds from individual F2, plants. Three peaks were observed in the F, generation of crosses between the mutants and "Century." Chisquare analysis of these distributions indicated that aileles from two independent loci segregated for palmitic acid percentage and that the alleles were additive in gene action. We propose gene symbols for the mutant alleles at these loci: fap2 for the allele in C1726 that acts to lower the palmitic acid percentage and fap2 for the allele in C1727 that acts to increase the palmitic acid percentage in soybean seed oil.
81 citations
TL;DR: Genotypic ratios within clutches of loggerhead turtle embryos, from the Mon Repos rookery (Queensland), deviate significantly from the Mendelian ratios expected on the null hypothesis of single paternity.
Abstract: Genotypic ratios within clutches of loggerhead turtle (Caretta caretta) embryos, from the Mon Repos rookery (Queensland), deviate significantly from the Mendelian ratios expected on the null hypothesis of single paternity. One-third of all clutches provide evidence for multiple insemination, indicating that multiple mating constitutes the major breeding pattern for C. caretta. Clutches from two females indicate that C. caretta females may mate between nestings.
65 citations
TL;DR: Determinisme genetique du comportement hygienique des abeilles de decoiffage and d'enlevement des larves mortes dans les cellules larvaires coiffees islamique.
Abstract: Determinisme genetique du comportement hygienique des abeilles de decoiffage et d'enlevement des larves mortes dans les cellules larvaires coiffees
65 citations
TL;DR: Dietary administration of various estrogens for three months from swim-up stage resulted in excess of females, the remainder of the treated groups consisting of males and hermaphrodites, suggesting viability of the YY genotype.
Abstract: Dietary administration of various estrogens for three months from swim-up stage resulted in excess of females, the remainder of the treated groups consisting of males and hermaphrodites. Mature hermaphrodites were self-fertilized or mated with standard males and females. These hermaphrodites and some of the estrogen-treated females proved to be genetic males; the frequencies of males obtained from their ova averaged 76.6%, suggesting viability of the YY genotype. Four of nine tested males of those progenies provided all male offspring when mated with standard females.
63 citations
TL;DR: Genetic evidence in D. ananassae suggests that crossing over is a meiotic event and is controlled by a series of suppressors and enhancers.
Abstract: Achiasmatic meiosis, or meiosis without crossing over, is characteristic of all higher Diptera males (suborder Brachycera). However, several cases of spontaneous crossing over in males have been reported in several different species. An examination of the published data suggests that recombinant chromosomes recovered from heterozygous males are usually the result of spontaneous crossing over in premeiotic cells. Mitotic, or somatic, crossing over probably occurs at a low frequency in all Diptera. When the crossover occurs in a gonial cell line, the recombinant chromosomes can be recovered in the gametes as presumptive meiotic crossovers. In cases where there is a translocation between the Y chromosome and an autosome, the segregation of the chromosomes from the translocation complex can produce aneuploids that phenotypically appear to be crossovers. Chromosome rearrangements and insertion elements, including the male sex-determining factor in Musca domestica and Megaselia scalaris, increase the frequency of exchange. Drosophlia ananassae appears to be an exception to the above. Genetic evidence in D. ananassae suggests that crossing over is a meiotic event and is controlled by a series of suppressors and enhancers.
55 citations
52 citations
TL;DR: The hybrids reported in this study provide additional information on intergenomic relationships among Brassica and related species of allied genera.
Abstract: The role of the x = 7 species, B. adpressa and Diplotaxis erucoides in Brassica evolution, was investigated by hybridizing them to the cultivated species B. nigra (x = 8) and B. oleracea (x = 9). In general, the hybrids displayed a low frequency of bivalents and unbalanced reductional division during meiosis, resulting in poor fertility. This cytological behavior was also observed in hybrids between the x = 7 species, indicating strong genome divergence of both genomes. Among all the hybrids, those of D. erucoides × B. nigra had the highest level of fertility, permitting the generation of D. erucoides-B. nigra alien addition lines. One of the hybrid plants variegated for yellow-white-red petal color and red pigmentation for other organs. The same enzyme activity zones were found to have multiple bands in all the species including those with x = 7 chromosomes, suggesting possible gene duplications. These multiple banded patterns persisted in pollen leachates and were transmitted to the hybrids. The hybrids reported in this study provide additional information on intergenomic relationships among Brassica and related species of allied genera.
TL;DR: Description du comportement somatique de l'allele «mutable» recessif du locus W 4 controlant la pigmentation en anthocyanes de the lignee Asgrow Mutable du soja.
Abstract: Description du comportement somatique de l'allele «mutable» recessif du locus W 4 controlant la pigmentation en anthocyanes de la lignee Asgrow Mutable du soja
TL;DR: A model for the differentiation of mammalian sex chromosomes and the evolution of the mechanism of X-chromosome inactivation is proposed that involves a gradual reduction of the Y chromosome and an accompanying gradual recruitment of (newly unpaired) X-linked loci under the control of a single inactivation center.
Abstract: Female mammals have two X chromosomes and males have a single X and a smaller, male-determining Y chromosome. The dosage of X-linked gene products is equalized between the sexes by the genetic inactivation of one X chromosome in females. The characteristics of the mechanism of X-chromosome inactivation differ in eutherian and metatherian mammals, and it has been suggested that the metatherian system represents a more primitive stage. The present study of monotreme sex chromosomes and X-chromosome inactivation suggests that the prototherian mammals may represent an even more primitive stage. There is extensive G-band homology between the monotreme X and Y chromosomes, and differences in the patterns of replication of the two X chromosomes in females suggest that X inactivation is tissue specific and confined to the unpaired segment of the X. On the basis of these results, we propose a model for the differentiation of mammalian sex chromosomes and the evolution of the mechanism of X-chromosome inactivation. This model involves a gradual reduction of the Y chromosome and an accompanying gradual recruitment of (newly unpaired) X-linked loci under the control of a single inactivation center.
TL;DR: The genetic basis of muscular dystrophy in golden retriever dogs was investigated by means of experimental matings and cytogenetic studies, and results were consistent with the X-linked recessive hypothesis.
Abstract: The genetic basis of muscular dystrophy in golden retriever dogs was investigated by means of experimental matings and cytogenetic studies. An affected male golden retriever was mated to three normal females, producing an F1 generation of six males and 14 females, all of which were clinically normal. Of six F1 females retained for breeding, all were shown to be carriers of muscular dystrophy in outcrosses to unrelated normal male dogs or in backcrosses to the affected male golden retriever. In outcrosses of carrier females, three of seven male and none of nine female offspring were affected, as expected under the X-linked recessive hypothesis. Backcrosses of F1 females to their affected sire also yielded results that are consistent with this hypothesis: 15 of 32 males and 5 of 17 females had muscular dystrophy. Cytogenetic studies of a carrier female, an affected male offspring, and a normal male sibling revealed no detectable abnormalities of the X chromosome.
TL;DR: The number of sex chromosomes in male and female larvae is discussed in relation to sex determination and the production of monogenous progenies.
Abstract: The somatic haploid chromosome set of the Hessian fly, Mayetiola destructor (Say),consists of two autosomes and two sex chromosomes. Female somatic cells have pairs of each of these chromosomes (2n = 8). Male somatic cells have two pairs of autosomes and two monosomic sex chromosomes. C-banding revealed pericentromeric heterochromatin on one arm of each chromosome. Mitotic chromosomes were karyotyped using relative lengths, centromeric positions, presence of secondary constrictions, and position and length of C-positive regions. Silver nitrate stained pericentromeric, heterochromatic regions on all four chromosomes but did not stain the entire C-positive regions. In female larvae, four distinct polytene chromosomes were found in the basal region cells of the salivary glands. In male larvae, two distinct and two diffuse polytene chromosomes were found in basal region cells. Differential polytene chromosome morphology in male and female larvae, polytene chromosome indexes, and the position of the nucleolus were used to establish correlations between mitotic and polytene chromosomes. The diffuse morphology of the polytene sex chromosomes in male larvae was probably related to dosage compensation. The number of sex chromosomes in male and female larvae is discussed in relation to sex determination and the production of monogenous progenies.
TL;DR: The Es-1 genotype was determined in newly developed congenic strains A.B6-Natr and B6.A-Nats, which will be important in determining the role of the NAT genotype in susceptibility to arylamine-induced cancer and other disorders.
Abstract: The human polymorphism in the hepatic enzyme N-acetyltransferase (NAT) affects the rate at which individuals acetylate, and in many cases detoxify, aromatic amine and hydrazine drugs and xenobiotics. Differences in NAT activity are known to affect individual susceptibility to drug toxicities and are thought to play a part in some spontaneous disorders. A mouse model for the human acetylation polymorphism has been previously characterized and involves the A/J (slow acetylator) and C57BL/6J (rapid acetylator) inbred strains. Strain distribution analysis of 40 A x B and B x A recombinant inbred (RI) strains indicated linkage between the N-acetyltransferase gene (Nat) and the esterase 1 (Es-1) gene, located on mouse chromosome 8. A double backcross involving 107 animals confirmed the recombination frequency between Nat and Es-1 to be 12 +/- 3% (mean +/- SE). The information obtained in the backcross and RI studies was combined, yielding a 13 +/- 2.8% (mean +/- SD) recombination frequency. The Es-1 genotype was determined in our newly developed congenic strains A.B6-Natr and B6.A-Nats. The B6.A-Nats strain has the Es-1 genotype of its inbred partner, the B6 strain, and the A.B6-Natr strain has the Es-1 genotype of the donor strain. These congenic strains will be important in determining the role of the NAT genotype in susceptibility to arylamine-induced cancer and other disorders.
TL;DR: Observation du polymorphisme des isozymes et de leur distribution dans differents pays en utilisant les systemes enzymatiques ACP, EST, MDH, ADH, PGD and PRX.
Abstract: Observation du polymorphisme des isozymes et de leur distribution dans differents pays en utilisant les systemes enzymatiques ACP, EST, MDH, ADH, PGD et PRX
TL;DR: Horizontal starch gel electrophoresis was used to perform genetic analysis to confirm the inheritance of various isozyme loci and report on additional loci in diploid Solanum species and provide new opportunities for further genetic studies of tuber-bearing Solanums.
Abstract: Horizontal starch gel electrophoresis was used to perform genetic analysis to confirm the inheritance of various isozyme loci and report on additional loci in diploid Solanum species. Aps-1, Dia-1, and ldh-1 were identified as new loci, and tetrasomic segregation was reported at the tetraploid level for Mdh-2. Of 15 loci studied, distorted segregations were observed in five diploid test crosses involving the Got-1, ldh-1, Pgi-1, and Adh-1 loci. In these cases, four of the five parents were of interspecific origin; the family segregating for Adh-1 was the exception. Utilizing various clones and interspecific combinations between S. phureja, S. tuberosum, and S. chacoense, further test crosses were made to determine linkage relationships between these isozyme loci and the yellow tuber flesh gene (Y). Two linkages were detected among these markers. Estimates of the ldh-1/Sdh-1 linkage ranged from 10.4 map units (m.u.) to 36.8 m.u., whereas a tight linkage was confirmed for Prx-2/Prx-3 (0.6 m.u.). Comparing putative homologous loci for the ldh-1/Sdh-1 linkage implies some conservation since the divergence of Lycoperison, Solanum, and, to a degree, Capsicum. As a result of codominant expression, these isozyme markers provide new opportunities for further genetic studies of tuber-bearing Solanums.
Journal Article•
TL;DR: A comparison of type specimens among the three Callitrichid genera showed that their phyletic radiation has been paralleled by a limited number of chromosome rearrangements and a relatively high amount of karyotypic invariance.
Abstract: A G-band karyotypic analysis was carried out in individual species groups of three Callitrichid primate genera: Cebuella, Callithrix, and Leontopithecus. Within Callithrix, the karyotypes of the morphologically distinct and geographically isolated morphotypes C. jacchus jacchus and C. jacchus penicillata were identical. Within the lion tamarin genus, Leontopithecus, the karyotypes of the three morphotypes (L. rosalia rosalia, L. rosalia chrysomelas and L. rosalia chrysopygus) were also indistinguishable from one another. These results are consistent with the taxonomic designation of subspecies rank to the different morphotypes. A comparison of type specimens among the three Callitrichid genera showed that their phyletic radiation has been paralleled by a limited number of chromosome rearrangements and a relatively high amount of karyotypic invariance. A fusion/fission event has been postulated to account for the difference in diploid number between Cebuella (2n = 44) and the other species (2n = 46). The karyotype of Callithrix jacchus was found to be more directly derived from Cebuella than was that of Leontopithecus. These findings differ from the previous proposition that Leontopithecus might have diverged from a common Callitrichid ancestor before the emergence of the genus Callithrix.
TL;DR: The mode of inheritance of cryptorchidism was investigated in Duroc swine, and two hypotheses were examined: first, that this trait is controlled by homozygosity of a recessive gene at a single locus; second, that it is controlled of recessive genes at two loci.
Abstract: The mode of inheritance of cryptorchidism was investigated in Duroc swine. Matings of cryptorchid males with females whose full-sib brothers were cryptorchids were done. Sixteen of these litters were farrowed, and 54 males were born, of which 8 were cryptorchid. Two hypotheses were examined: first, that this trait is controlled by homozygosity of a recessive gene at a single locus; second, that it is controlled by homozygosity of recessive genes at two loci. The single-locus recessive hypothesis was rejected (P less than .01), but the two-locus model was not. Culling to reduce the incidence of cryptorchidism is discussed.
TL;DR: These findings resemble the ultrastructural features of human hypothyroid goiter caused by a thyroglobulin (TG) defect and thus support the previously suggested abnormalities of TG synthesis and/or processing in cog/cog mice.
Abstract: Thyroids of congenitally goitrous (cog/cog) mice were studied with light and electron microscopy. The principal alteration in follicular cells was their largely overdistended rough endoplasmic reticulum (RER). Our findings resemble the ultrastructural features of human hypothyroid goiter caused by a thyroglobulin (TG) defect and thus support the previously suggested abnormalities of TG synthesis and/or processing in cog/cog mice.