Journal of Heredity

Kahler, A. L.; Morris, M. I.; Allard, R. W.

doi: 10.1093/oxfordjournals.jhered.a109534pmid: N/A

Abstract The Est 4 locus in wild and domestic barley features double-banded homozy-gotes and quadruple-banded heterozygotes. Electrophoretic assays of 60 individuals of a diploid accession (P.I. 296897) of H. spontaneum and 2400 selfed progeny derived from these 60 plants revealed that this accession is monomorphic and true breeding for a six-banded phenotype. It is postulated that the six-banded type is due to fixed triplication, with alleles 5.5, 6.2, and 6.6 each present in homozygous condition. Because P.I. 296897 is reproductively isolated from all other barleys with which it has been crossed, it is concluded that this wild barley phenotype may represent a case of sympatric speciation. Triplication is discussed as the possible isolating mechanism. This content is only available as a PDF. © 1981 by the American Genetic Association

Curtsinger, James W.

doi: 10.1093/oxfordjournals.jhered.a109535pmid: N/A

Abstract Experiments were undertaken to detect genetic variation for the sex ratio in D. pseudoobscura that is independent of the “sex-ratio” (SR) meiotic drive system. Females inseminated in a natural population produce broods that are heterogeneous with respect to sex ratio. Lines selected for high percentage of male progeny responded in one of two independent artificial selection experiments; the realized heritability was 0.101. Interline crosses between the selected high (percent males) line, low line, and an unselected standard stock reveal a significant male effect, nonsignificant female effect, and marginally significant interaction. Selection gains were rapidly lost when selection was relaxed. Males carrying the SR X-chromosome on a genetic background selected for high percentage of males show no modification of SR meiotic drive. It is suggested that populations are polymorphic for autosomal or X-linked variants that modify the segregation of sex chromosomes and are maintained in a polymorphic state by a balance between segregation and zygotic selection. This content is only available as a PDF. © 1981 by the American Genetic Association

Kiang, Y. T.

doi: 10.1093/oxfordjournals.jhered.a109536pmid: N/A

Abstract The activity of amylase at Am-1 and Am- 2 loci represents α-amylase while that at Am-3 locus represents B-amylase. In transmisions, the three loci usually behave as a single unit. The Am-3 locus has four variants F, S, Sw and n1 which are allelic in their effects on Am-3. Fand the S are codominant; Sw is recessive to F and the S1 but dominant over n1. The n1 variant may be a recent mutation that occurred in the cultivar Altona. In cultivated soybeans (G. max) only 0.42 percent of heterozygous seed were detected among 1905 seed from 176 cultivars. These heterozygous seed represent the product of natural outcrossing. The wild soybean (G. soja) seed collected from Japan and Korea showed 31.8 percent and 25.7 percent polymorphism, respectively. The average heterozygosity is 8.1 percent and 7.4 percent for Japanese and Korean collections, respectively. Seed of Neo-notonia wightii show no amylase activity except in two accessions from South Africa. This content is only available as a PDF. © 1981 by the American Genetic Association

Wilcox, Frank H.; Taylor, Benjamin A.

doi: 10.1093/oxfordjournals.jhered.a109537pmid: 7334202

Abstract Differences between strains of mice were observed in electrophoretic migration on cellulose acetate plates of alkaline phosphatase in butanol extracts of kidney, bone, and placenta. Each strain exhibited a broad band with fast or slow migration. Distribution among strains including recombinant inbred (Rl) strains indicated the variation in these organs to be the same as that previously described in the liver as coded for by the Akp-2 locus. An analysis of Rl strains for the kidney isozyme showed 43 with the faster moving form (AKP-2A), and 43 with the slower moving form (AKP-2B), and thus in the 1:1 ratio expected if a single locus is responsible for the strain differences. Comparisons of Rl strains showed linkage of the Akp-2 locus to two loci on chromosome 4 as follows: centromere—Gpd-1—5.7 ± 1.9 cM—Akp-2—0.6 ± 0.4 cM—Ahd-1. These data are based on 82 Rl strains typed for both the first and second loci, and 86 for the second and third loci. This content is only available as a PDF. © 1981 by the American Genetic Association

Gill, B. S.

doi: 10.1093/oxfordjournals.jhered.a109538pmid: N/A

Abstract The heterochromatin band patterns (C-bands) were used to identify individual chromosomes in Aegilops caudata, Ae. umbellulataAe. mutica, Elymus junceus, Haynal-dia villosa, and Agropyron spicatum. The heterochromatin bands were developed least in the first two Aegilops species; intermediate in Ae. mutica and Elymus, and highly developed in A. spicatum and H. villosa. Since C-bands represent sites of highly repetitive DNA, a part of the mechanism of genome evolution in these grasses has been by DNA amplification. Based on heterochromatin bands, Ae. caudata and Ae. umbellulata are more ciosely related to each other than to Ae. mutica. At the generic level, Agropyron and rye appear to be more closely related to each other than to Aegilops or Triticum. Ae. mutica and H. villosa did not appear to be the donors of the B genome to wheat. This content is only available as a PDF. © 1981 by the American Genetic Association

Stansfield, William D.

doi: 10.1093/oxfordjournals.jhered.a109539pmid: 7334203

Abstract Viable mice homozygous for two recessive autosomal genes, hairless (hr) and obese (ob) were produced with an average life span of 538 ± 34.1 days. On the average, hairless-obese mice weighed about 73 percent as much as obese mice. Since obese mice consumed approximately 73 percent as much oxygen per gram body weight per hour as hairless-obese mice at about 24°C, the weight averages appear to be closely inversely related to the oxygen consumption averages. The presence or absence of pelage seems to make a negligible contribution to oxygen consumption in these two types of obese mice. The hairless condition of the hr/hr genotype seems to contribute to increased oxygen consumption beyond that expected as a consequence of their lower average body weight. The average oxygen consumptions for seven female mice in each of four phenotypic groups (hairless, normal, hairless-obese, and obese) were 3.87, 3.12, 2.39, and 1.74 ml/g/hr, respectively. The two mutants appear to interact in a simple additive way and not as a mutant suppression system. On an absolute basis, the hr/hr genotype seems to have approximately 54 pecent as much affect on oxygen consumption as the ob/ob genotype. Litter records at about 60 days of age for four kinds of matings did not reveal any statistically significant deviations from expected ratios. This content is only available as a PDF. © 1981 by the American Genetic Association

Robertson, Donald S.; Hallauer, Arnel R.; Kevern, T. C.

doi: 10.1093/oxfordjournals.jhered.a109540pmid: N/A

Abstract Four modified W22 inbred lines were studied in which the distal 65 percent of the long arm of chromosome 10 had been incorporated from inbred lines B55, Oh93, CI187-2, and M14. These substituted lines were analyzed with respect to 11 plant and ear traits, in hybrid combinations with each other, and as hybrids with W22. In most instances, the substituted lines djd not perform as well as W22. In a few instances, performance was equal to W22, but never greater. Some hybrid combinations performed better than W22 in some traits, but jn no instances did hybrid combinations outperform the best substituted parent line. Heterotic effects were observed in nine instances involving hybrids between W22 and the substituted lines. These latter observations suggest that substituted inbred lines may provide insight into the role of certain chromosomal segments in heterosis. This content is only available as a PDF. © 1981 by the American Genetic Association

Stalker, H. T.; Dalmacio, R. D.

doi: 10.1093/oxfordjournals.jhered.a109541pmid: N/A

Abstract Mitotic chromosomes of eight section Arachis species of the genus Arachis were analyzed cytologically. The species observed included A. batizocoi, A. cardenasii, A. chacoense, A. correntina, A. duranensis, A. spegazzinii, A. stenosperma, and A. villo-sa. The chromosomes were small, ranging in length from 1.4 to 3.9 fim, and were placed in three groups: chromosomes 1 to 3 were nearly the same length; 4 to 7 were of medium length; and 8 to 10 were shorter. Based on centromere position, chromosome length, secondary constrictions, and differential staining of heterochromatic and euchromatic regions, all 10 homologues of each species were identified. The data correspond favorably to the hypothesis that section Arachis species have two genomes, with most species having the A genome and A. batizocoi having the B genome. The A genome can be further divided into three karyological groups as follows: A1 = A. cardenasii; A2 = A. chacoense, A. duranensis, and A . stenosperma; and A3 = A. correntina,A. spegazzinii, and A. villosa. Although each of the eight species was cytologically identified, the three members of group A3 were extremely difficult to differentiate by observing somatic chromosomes. The groups of species with the A genome generally followed a north-south distribution pattern and the three most southerly species did not have satellited chromosomes. Additional species need to be observed before these trends can be confirmed. Because A. batizocoi had the most asymmetrical genome among the observed species, it may be of more recent origin than other taxa of this group. This content is only available as a PDF. © 1981 by the American Genetic Association

Lane, Priscilla W.; Searle, Antony G.; Beechey, Colin V.; Eicher, Eva M.

doi: 10.1093/oxfordjournals.jhered.a109542pmid: 6949984

Abstract Evidence is presented that places LG XV on chromosome 18 and shows that the centromere is at the Tw end of the chromosome. The linear order and distances of the three marker genes on Chr 18 are shown to be centromere—10—Tw—14—be—11— sy. They occupy a total genetic length of 35 cM. The positions of the breakpoints of the two reciprocal translocations T(10; 18) 18H and T(7;18)50H are discussed and shown to be closely linked to the sy locus. This content is only available as a PDF. © 1981 by the American Genetic Association

Burns, J. A.; Gerstel, D. U.

doi: 10.1093/oxfordjournals.jhered.a109543pmid: N/A

Abstract Combining the cytoplasm from one species of Nicotiana with the nucleolus from another often results in male sterility. The damage may be reduced by addition of a chromosome from the genome of the cytoplasm donor. This was shown previously, when chromosomes from N. tabacum were substituted in the cytoplasms of N. repanda and N. debneyi, and again in the current study with cytoplasm from N. undulata. In all three combinations, the restorer chromosomes carried nucleolar organizing regions (NOR's), were consistently associated with nucleoli at meiotic prophase, and exhibited satellites in somatic metaphases. Furthermore, activity of NOR's of N. tabacum chromosomes was weakened by amphiplasty. Fragment chromosomes having the NOR from the cytoplasm donor and only a small portion of the remainder of the chromosome behaved like the intact chromosomes. One may thus surmise that an interaction between NOR's and cytoplasm from the same species is required for anther development. A theoretical model for this relationship is proposed. Close and highly conserved linkage between ribosomal DNA cis-trons of the NOR and restorer(s), or a nonspecific effect of NOR heterochromatin are other possibilities. This content is only available as a PDF. © 1981 by the American Genetic Association