Journal of Heredity

Cramer, D., V.;Chakravarti,, A.;Arenas,, O.;Humprieres,, J.;Mowery, P., A.

doi: 10.1093/oxfordjournals.jhered.a110522pmid: 3183358

Abstract The levels of gene diversity for 17 polymorphic loci in natural populations of wild rats were examined for three separate locations in North and South America. The level of gene diversity in the total sample for the RT1.A locus, the dominant class I histocompatibility locus in the major histocompatibility (RT1) complex of the rat, was 0.807. The degree of gene diversity for nonalloantigenic loci scattered throughout the rat genome was 0.215, a level comparable to, if not slightly higher than, that for other mammalian species. The large and consistent levels of diversity for individuals within each population suggest that significant deviations from random mating have occurred within each group. Conclusions from analyzing genetic distance and the index of genetic differentiation between the three populations are consistent with these populations' geographic isolation and small effective population size. Assuming that the separation of the North and South American groups has existed for approximately 300 years, the effective size of these populations is estimated to be approximately 1,500 individuals. Apparent differences in the distribution of the number and frequency of alleles in the major histocompatibility complexes of mice and rats and the level of genetic differentiation among separate rat populations may be due to the effects of genetic drift in small populations. This content is only available as a PDF. © 1988 The American Genetic Association

Georgiadis,, N.;Dunham,, P.;Read,, B.;Templeton,, A.

doi: 10.1093/oxfordjournals.jhered.a110523pmid: 3183359

Abstract Concentrations of potassium (K) and sodium (Na) were determined in the erythrocytes of 28 members of an interbreeding herd of Speke's gazelle. The distribution of K concentrations and Na/K concentration ratios suggested the presence of the high-K/low-K (HK/LK) polymorphism known in erythrocytes of domestic bovids. The pedigree of the herd of gazelles is known completely, permitting examination of the inheritance of HK/LK polymorphism by overlaying the distribution of phenotypes on the pedigree. Statistical analyses clearly Indicate a strong genetic component in the phenotypic variability that is entirely consistent with a single autosomal locus, two-allele mode of inheritance, with the LK allele being dominant. This is the first demonstration of HK/LK polymorphism in a wild bovid species. The evidence indicates that HK/LK polymorphism is of considerable evolutionary age, is of monophyletic origin, and is maintained by selection. This content is only available as a PDF. © 1988 The American Genetic Association

Kopp,, E.;Mayr,, B.;Kalat,, M.;Schleger,, W.

doi: 10.1093/oxfordjournals.jhered.a110524pmid: 31581761

Abstract Chromomycin A3 (CMA3) banding in mitotic sets of the Equidae horse and donkey were used to demonstrate both constitutive heterochromatin and R-banding. Intra and Interindividual variation In the size of the heterochromatic blocks was observed In many cases. CMA3-posittve telomeric heterochromatin blocks appeared on several chromosomes of the horse and donkey. Some of them were especially spectacular in the donkey. A sequential silver NOR-chromomycin A3/distamycln A-DAPI (CDD) staining procedure led to the detection of the localization of active nucleolus-organizing regions (NORs) and to the identification of chromosomes. The data revealed individual specific NOR patterns in both species. This content is only available as a PDF. © 1988 The American Genetic Association

Gustavsson,, I.;Świtoński,, M.;Larsson,, K.;Plöen,, L.

doi: 10.1093/oxfordjournals.jhered.a110525pmid: 31581762

Abstract Investigations of male meiosis in silver fox x blue fox hybrids have revealed meiotic arrest at the first prophase stage. Synaptonemal complex analysis using light and electron microscopy demonstrated the occurrence of multivalents, bivalentlike structures, and unpaired axes. We conclude that the sterility of male hybrid foxes probably is due to pairing problems of chromosomes caused by extensive karyotypical differences of the two species, resulting in unpaired chromosomes, chromosome segments, and broken chromosomes. This content is only available as a PDF. © 1988 The American Genetic Association

Gethmann, R., C.

doi: 10.1093/oxfordjournals.jhered.a110526pmid: 31581763

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. This content is only available as a PDF. © 1988 The American Genetic Association

Quiros, C., F.;Ochoa,, O.;Douches, D., S.

doi: 10.1093/oxfordjournals.jhered.a110527pmid: 31581764

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. This content is only available as a PDF. © 1988 The American Genetic Association

Brown, D., C.;Ropson, I., J.;Powers, D., A.

doi: 10.1093/oxfordjournals.jhered.a110528pmid: 31581765

Abstract Starch gel electrophoresis has shown that natural populations of Fundulus heteroclitus have electrophoretic variants for at least 21 loci. We provide inheritance data for 10 polymorphic systems: esterases (Est-B, EST-C, and Est-D); aspartate amlnotransferases (Aat-A, and Aat-B); mannosephosphate isomerase (Mpl-A); acid phosphatase (Ap-A); phosphoglucomutase (Pgm-B); hexose-6-phosphate dehydrogenase (H6pdh-A); and fumarase (Fum-A). Variants for nine of these loci segregate as autosomally inherited codominant alleles. The other system, EST-C, does not reflect such inheritance. We have identified two possible linkage groups: H6pdh-A may be loosely linked to Pgm-B, and Fum-A appears to be linked to Pgm-A. Tissue specificity and intracellular localization for all these loci are also presented. This content is only available as a PDF. Author notes Dr. Brown is currently at the Department of Biochemistry, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland. Dr. Ropson is currently at the Department of EPO Biology, University of Colorado, Boulder © 1988 The American Genetic Association

Endo, T., R.

doi: 10.1093/oxfordjournals.jhered.a110529pmid: 31581766

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. This content is only available as a PDF. © 1988 The American Genetic Association

Prina, A., R.;Favret, E., A.

doi: 10.1093/oxfordjournals.jhered.a110530pmid: 31581767

Abstract Mutagenic agents have been evaluated in terms of their effects on germ cells. The study of induced somatic mutations is a faster, more economical, and less laborious method than the traditional ones. The induction of somatic sectors by x-rays, ethyl methanesulfonate, and sodium azide was studied in cultivated barley. Four stocks were used: a normal one, a balanced lethal genotype carrying two chlorophyll-deficiency genes of different expression (albina and golden), and two (semidominant) chlorophyll mutants of the same dominant gene, which in the progeny of selling segregate 1 normal green: 2 light green: 1 yellow seedlings. Treatments were applied to seeds, and the fourth, fifth, and sixth leaves of the main shoot were examined in the M1 generation for the presence of sectors showing conspicuous changes in chlorophyll content. Highly significant frequencies of dark green sectors were induced by all three mutagens in the (semidominant) heterozygous plants, whereas evidence of somatic crossing over or mitotic nondisjunction was very rare in this material and in the balanced lethal genotype. In all cases, the frequencies of induced sectors without chlorophyll were much higher in the heterozygotes than in the normal homozygotes, with each mutagen showing typical dose-response curves. A notable interaction between mutagen and genotype was found. The variation in the relative frequencies of sector types in the various genotypes points to the differential influence of the marker genes. This content is only available as a PDF. © 1988 The American Genetic Association

Douches, D., S.;Quiros, C., F.

doi: 10.1093/oxfordjournals.jhered.a110531pmid: 31581768

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. This content is only available as a PDF. Author notes Dr. Douches is currently at the Department of Crop and Soil Science, Michigan State University, East Lansing. © 1988 The American Genetic Association