scholarly journals FURTHER EVIDENCE FOR A POLYMORPHISM IN GAMETIC SEGREGATION IN THE TETRAPLOID TREEFROG HYLA VERSICOLOR USING A GLUTAMATE OXALOACETIC TRANSAMINASE LOCUS

Genetics ◽  
1983 ◽  
Vol 103 (4) ◽  
pp. 753-769
Author(s):  
Roy G Danzmann ◽  
James P Bogart
Keyword(s):  
Chromosome Segregation ◽  
Null Allele ◽  
Interspecific Cross ◽  
Staining Intensity ◽  
Interspecific Crosses ◽  
Hyla Versicolor ◽  
Hyla Chrysoscelis ◽  
Segregation Ratios ◽  
Aberrant Segregation ◽  
Glutamate Oxaloacetic Transaminase

ABSTRACT Intra- and interspecific cross combinations between the tetraploid treefrog Hyla versicolor, and between H. versicolor and the diploid treefrog Hyla chrysoscelis were performed. Progeny phenotypes resulting from these crosses were examined electrophoretically using a polymorphic glutamate oxaloacetic transminase (GOT-1) locus, to determine the mechanism of chromosome segregation in H. versicolor, and to test theoretical expectations for isozyme expression in interspecific (2n × 4n or 4n × 2n) hybrids. In some intraspecific tetraploid crosses progeny phenotypes fit a disomic mode of segregation, whereas in other crosses a tetrasomic mode of segregation was the most probable. Additional crosses produced phenotypic ratios that conformed to either a disomic or tetrasomic mode of segregation. These results suggest that a polymorphism, with respect to segregation of gametes, exists in H. versicolor, resulting from differences in chromosome pairings during meiosis I. This polymorphism in gametic segregation occurred in both sexes. Certain crosses, however, produced phenotypic ratios that did not conform to any chromosome segregation model. Progeny phenotypes observed from most interspecific crosses conformed to expected interspecific isozyme staining intensity models. Symmetrical heterozygotes, representing either a single dose for both alternate alleles or double doses for both alternate alleles, were also observed. Such phenotypes are unexpected in triploid progeny. A null allele was postulated to account for the aberrant segregation ratios and phenotypes observed in certain intra- and interspecific crosses.

scholarly journals Inheritance and Linkage Relationships of Isozymes in Easter Cactus

1998 ◽  
Vol 123 (1) ◽  
pp. 98-103
Author(s):  
Maureen C. O'Leary ◽  
Thomas H. Boyle
Keyword(s):  
Interspecific Hybrids ◽  
Triosephosphate Isomerase ◽  
Recombination Frequency ◽  
Polyacrylamide Gel Electrophoresis ◽  
Interspecific Crosses ◽  
Germplasm Collections ◽  
Segregation Ratios ◽  
Isozyme Loci ◽  
Linkage Relationships ◽  
Aberrant Segregation

Polyacrylamide gel electrophoresis was used to study inheritance and linkage of isozymes in Easter cactus (Hatiora species and interspecific hybrids). Five isozyme systems were analyzed: aspartate aminotransferase (AAT), glucose-6-phosphate isomerase (GPI), malate dehydrogenase (MDH), phosphoglucomutase (PGM), and triosephosphate isomerase (TPI). F1, F2, BC1, and S1 progeny were used for inheritance studies. Six polymorphic loci (Aat-1, Gpi-1, Mdh-1, Pgm-1, Pgm-2, and Tpi-2) were identified. Aat-1 and Pgm-1 were linked (recombination frequency = 26% ± 7%), but the other isozyme loci assorted independently. Aberrant segregation ratios were observed in at least one segregating family for all six isozyme loci. We hypothesize that segregation distortion was due to linkage between isozyme loci and other genes subject to pre- or postzygotic selection. The existence of five additional isozyme loci (Aat-2, Gpi-2, Mdh-2, Mdh-3, and Tpi-1) was inferred from segregation patterns and by comparison of isozyme profiles from phylloclades and pollen. These isozyme loci may prove useful for confirming hybridity in intra- and interspecific crosses, determining parentage of cultivars, and assessing genetic diversity in germplasm collections.

scholarly journals Single-Locus Inheritance in the Tetraploid Treefrog Hyla versicolor With an Analysis of Expected Progeny Ratios in Tetraploid Organisms

Genetics ◽  
1987 ◽  
Vol 116 (2) ◽  
pp. 299-311
Author(s):  
J Ellen Marsden ◽  
Steven J Schwager ◽  
Bernie May
Keyword(s):  
Null Allele ◽  
Hyla Versicolor ◽  
Crossing Over ◽  
Tetraploid Species ◽  
Double Reduction ◽  
Adequate Knowledge ◽  
Disomic Inheritance ◽  
Segregation Ratios ◽  
Minimum Number ◽  
Species Being

ABSTRACT The recently evolved autotetraploid frog, Hyla versicolor, was examined electrophoretically for evidence of genomic restructuring leading to diploidization. Loci were tested against the progeny ratios expected if inheritance was disomic vs. tetrasomic. Two loci (Mpi and Sod-2) appeared to be inherited tetrasomically, one (Mdh-2) appeared to be inherited disomically, and one (Tpi) appeared to be inherited disomically in one family and tetrasomically in another family, when tested conventionally against 1:2:1 and 1:4:1 segregation ratios. The minimum number of progeny required for this type of analysis for codominant alleles is shown to be 92. Progeny resulting from double reduction were observed, and the occurrence of a null allele class at Mpi was noted. A reexamination of expected progeny ratios in tetraploid organisms reveals that tetrasomic inheritance patterns cannot be predicted without adequate knowledge of the amount of crossing-over, the proportion of tetravalents vs. random bivalents that are formed, and the ratio and types of centromere segregation (alternate and adjacent) that occur from tetravalents in the species being studied. However, disomic inheritance can be unambiguously confirmed only by the production of all heteroallelic gametes from homobivalent, symmetrically heterozygous individuals. In addition, a method is described for estimating genecentromere distances using the ratio of progeny genotypes in certain crosses in tetraploid species.

scholarly journals Geographical variation in postzygotic isolation and its genetic basis within and between two Mimulus species

2010 ◽  
Vol 365 (1552) ◽  
pp. 2469-2478 ◽  
Author(s):  
Noland H. Martin ◽  
John H. Willis
Keyword(s):  
Pollen Fertility ◽  
Genetic Basis ◽  
Interspecific Cross ◽  
Local Scale ◽  
Interspecific Crosses ◽  
Postzygotic Isolation ◽  
Hybrid Fitness ◽  
Pure Species ◽  
Geographical Scale ◽  
Germination Success

The aim of this study is to investigate the evolution of intrinsic postzygotic isolation within and between populations of Mimulus guttatus and Mimulus nasutus . We made 17 intraspecific and interspecific crosses, across a wide geographical scale. We examined the seed germination success and pollen fertility of reciprocal F 1 and F 2 hybrids and their pure-species parents, and used biometrical genetic tests to distinguish among alternative models of inheritance. Hybrid seed inviability was sporadic in both interspecific and intraspecific crosses. For several crosses, Dobzhansky–Muller incompatibilities involving nuclear genes were implicated, while two interspecific crosses revealed evidence of cytonuclear interactions. Reduced hybrid pollen fertility was found to be greatly influenced by Dobzhansky–Muller incompatibilities in five out of six intraspecific crosses and nine out of 11 interspecific crosses. Cytonuclear incompatibilities reduced hybrid fitness in only one intraspecific and one interspecific cross. This study suggests that intrinsic postzygotic isolation is common in hybrids between these Mimulus species, yet the particular hybrid incompatibilities responsible for effecting this isolation differ among the populations tested. Hence, we conclude that they evolve and spread only at the local scale.

scholarly journals Development of a core RFLP map in maize using an immortalized F2 population.

Genetics ◽  
1993 ◽  
Vol 134 (3) ◽  
pp. 917-930 ◽  
Author(s):  
J M Gardiner ◽  
E H Coe ◽  
S Melia-Hancock ◽  
D A Hoisington ◽  
S Chao
Keyword(s):  
Zea Mays L ◽  
Mapping Population ◽  
F2 Population ◽  
Rflp Map ◽  
Length Polymorphisms ◽  
Segregation Ratios ◽  
Maize Genetic ◽  
Immortalized F2 ◽  
Genomic Regions ◽  
Aberrant Segregation

Abstract A map derived from restriction fragment length polymorphisms (RFLPs) in maize (Zea mays L.) is presented. The map was constructed in an immortalized Tx303 x CO159 F2 mapping population that allowed for an unlimited number of markers to be mapped and pooled F3 seed to be distributed to other laboratories. A total of 215 markers consisting of 159 genomic clones, 16 isozymes and 35 cloned genes of defined function have been placed on 10 chromosomes. An examination of segregation data has revealed several genomic regions with aberrant segregation ratios favoring either parent or the heterozygote. Mapping of cloned genes and isozymes that have been previously mapped by functional criteria has provided 29 points of alignment with the classical maize genetic map. Screening of all mapped RFLP probes against a collection of U.S. Corn Belt germplasm using EcoRI, HindIII and EcoRV has resulted in a set of 97 core markers being defined. The designation of a set of core markers allows the maize genome to be subdivided into a series of bins which serve as the backbone for maize genetic information and database boundaries. The merits and applications of core markers and bins are discussed.

scholarly journals RECOMBINATION AND CHROMOSOME SEGREGATION DURING THE SINGLE DIVISION MEIOSIS IN SPO12–1 AND SPO13–1 DIPLOIDS

Genetics ◽  
1980 ◽  
Vol 96 (3) ◽  
pp. 589-611 ◽  
Author(s):  
Sue Klapholz ◽  
Rochelle Easton Esposito
Keyword(s):  
Chromosome Segregation ◽  
Chromosome Iii ◽  
Mat Locus ◽  
Aberrant Segregation ◽  
Meiosis I

ABSTRACT This paper reports a study of chromosome segregation and recombination during sporulation of spo12—1 and spo13–1 diploid strains of S. cerevisiae. These strains undergo a single division to form asci containing two diploid or near-diploid spores. The segregation of centromere-linked markers in the two-spored (dyad) products indicates that the division is generally equational. However, in a small percentage of the spo12–1 and spo13–1 cells, it appears that a meiosis I-like division occurs. Aberrant segregation of the MAT locus on chromosome III, yielding a monosomic and a trisomic spore pair, occurs in 12% of all dyads. The segregation patterns of markers at various distances from their centromeres and several pairs of markers on the same chromosome indicate that recombination takes place in both strains at nearly standard meiotic levels.

Pollination Sub-Systems Distinguished by Pollen Tube Arrest after Incompatible Interspecific Crosses in Rhododendron (Ericaceae)

1982 ◽  
Vol 53 (1) ◽  
pp. 255-277
Author(s):  
ELIZABETH G. WILLIAMS ◽  
BRUCE R. KNOX ◽  
JOHN L. ROUSE
Keyword(s):  
Pollen Tube ◽  
Tip Growth ◽  
Interspecific Cross ◽  
Embryo Sac ◽  
Epifluorescence Microscopy ◽  
Interspecific Crosses ◽  
Abnormal Behaviour ◽  
Callose Deposition ◽  
Variable Diameter ◽  
Stigmatic Exudate

The cytology of compatible and interspecific incompatible pollinations has been followed in selected species of the genus Rhododendron (Ericaceae). Pollinated pistils were fixed, cleared, stained in decolourized aniline blue, and observed by epifluorescence microscopy. Ten different abnormalities of arrested pollen tube tips have been detected, including burst, tapered, swollen, coiled, spiralling, spiky and variable diameter syndromes. A series of five errors of callose deposition in incompatible tubes has also been defined. Six different regions in the pistil for expression of pollen tube arrest have been found, including the stigmatic exudate, the mucilage of the upper and lower style canal, the ovary loculus, the micropyle. There may also be abnormal behaviour after entry into the embryo sac. Both the site of pollen tube arrest within the pistil, and the error syndrome of tip growth and callose deposition anomalies, are characteristic of each interspecific cross. These results are discussed in relation to the genetic control of reproduction.

Comparative contractile dynamics of calling and locomotor muscles in three hylid frogs.

1995 ◽  
Vol 198 (7) ◽  
pp. 1527-1538 ◽  
Author(s):  
D McLister ◽  
E D Stevens ◽  
J P Bogart
Keyword(s):  
Relaxation Time ◽  
Isometric Tension ◽  
Hyla Versicolor ◽  
Hyla Chrysoscelis ◽  
Shortening Velocity ◽  
Call Production ◽  
Mating Call ◽  
Locomotor Muscles ◽  
Force Velocity ◽  
Isometric Twitch

Isometric twitch and tetanus parameters, force-velocity curves, maximum shortening velocity (Vmax) and percentage relaxation between stimuli (%R) across a range of stimulus frequencies were determined for a muscle used during call production (the tensor chordarum) and a locomotor muscle (the sartorius) for three species of hylid frogs, Hyla chrysoscelis, H. versicolor and H. cinerea. The call of H. chrysoscelis has a note repetition rate (NRR) approximately twice as fast as the call of H. versicolor (28.3, 42.5 and 56.8 notes s-1 for H. chrysoscelis and 14.8, 21.1 and 27.4 notes s-1 for H. versicolor at 15, 20 and 25 degrees C, respectively). Hyla cinerea calls at a very slow NRR (Approximately 3 notes s-1 at 25 degrees C). Hyla versicolor evolved from H. chrysoscelis via autopolyploidy, so the mating call of H. chrysoscelis is presumably the ancestral mating call of H. versicolor. For the tensor chordarum of H. chrysoscelis, H. versicolor and H. cinerea at 25 degrees C, mean twitch duration (19.2, 30.0 and 52.9 ms, respectively), maximum isometric tension (P0; 55.0, 94.4 and 180.5 kN m-2, respectively), tetanic half-relaxation time (17.2, 28.7 and 60.6 ms, respectively) and Vmax (4.7, 5.2 and 2.1 lengths s-1, respectively) differed significantly (P < 0.05) among all three species. The average time of tetanic contraction to half-P0 did not differ significantly between H. chrysoscelis (14.5 ms) and H. versicolor (15.8 ms) but was significantly longer for H. cinerea (52.6 ms). At 25 degrees C, Vmax differed significantly among the sartorius muscles of H. chrysoscelis, H. versicolor and H. cinerea (5.2, 7.0 and 9.8 lengths s-1, respectively) but mean twitch duration (29.5, 32.2 and 38.7 ms, respectively), P0 (252.2, 240.7 and 285.1 kN m-2, respectively) and tetanic half-relaxation time (56.3, 59.5 and 60.7 ms, respectively) did not differ significantly. The average time of contraction to half-P0 did not differ significantly between H. chrysoscelis (23.7 ms) and H. versicolor (22.9 ms) but was significantly shorter for H. cinerea (15.6 ms). The only consistent contractile differences found in this study between the calling muscle and locomotor muscle of H. chrysoscelis, H. versicolor and H. cinerea were that the calling muscles generated less tension and their force-velocity relationship was much more linear. These differences may be attributable to ultrastructural differences between calling and locomotor muscles.(ABSTRACT TRUNCATED AT 400 WORDS)

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