bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosomal variation in pine voles, Microtus (Pitymys) pinetorum, in the eastern United States
Authors: Wilson John W.
Published: November 2014

As part of a study of the population biology of pine voles (Microtus (Pitymys) pinetorum), 65 voles were karyotyped from seven apple orchard populations in the eastern United States. All animals had 62 chromosomes. Voles from New Hampshire and New York had 62 autosomal arms, whereas those from Virginia and North Carolina had 64. Voles from one population in southern Pennsylvania had 62, 63, or 64 arms in approximate Hardy–Weinberg proportions. The polymorphism resulted from the presence or absence of secondary arms on the largest pair of autosomes. There appears to be no reproductive isolation between the cytotypes in the Pennsylvania population.Key words: Microtus pinetorum, Pitymys, chromosomal variation, karyotype.
Nucleolar variation in a pigeon pea intergeneric hybrid: evidence for allosyndetic recombination
Authors: Kumar P. Sateesh , Subrahmanyam N. C. , Faris D. G.
Published: November 2014

Cytological study of a hybrid between Cajanus cajan and Atylosia albicans revealed regular bivalent formation and disjunction. Nevertheless, high pollen sterility and low seed set were evident. An examination of pollen mother cells revealed variation in nucleolar number at telophase-I (four to eight) and at telophase-II (zero to four in daughter nuclei), although each genome contained two nucleolar organizers. Variation was also recorded for nucleolar size and distribution at telophase-II. Variation in nucleolar number and distribution are interpreted to have originated from pairing and recombination between nucleolar organizer chromosome(s) of one parental species with the nonnucleolar organizer chromosome(s) of the other. Size variation is attributed to nucleolar dominance. These results explain the high degree of pollen sterility in the hybrid in spite of normal meiosis, and also suggest that the karyotypes of C. cajan and A. albicans have differentiated through structural heterozygosity.Key words: Cajanus cajan, Atylosia albicans, nucleolar variation, structural heterozygosity, allosyndetic recombination.
Line × tester crosses: a new approach of analysis
Authors: Patel J. D. , Christie B. R. , Kannenberg L. W.
Published: November 2014

A new theory is presented which analyses a line × tester experiment and yields diallel forms of genetic parameters for both lines and tester populations. The procedure accounts for the different allelic frequencies for the same locus in two homozygous populations, viz., lines and testers. Sufficient statistics like variance of array means [Formula: see text], mean variance of arrays [Formula: see text], mean covariance of array upon noncommon parent [Formula: see text], and covariance of array means upon common parents [Formula: see text] can be derived, in addition to variance of lines (VI) and variance of testers (VT). A total of nine statistics can be solved by the least squares method to get eight different parameters. Further, regression of Wr1 upon Vr1 in each kind of array has an expected value of unity with the additive – dominance model and therefore, deviations from unity can be used to test for the presence of epistasis or disturbing factors. The practical limitation of the diallel can be overcome by this approach when a large number of homozygous parents are to be evaluated.Key words: line × tester, diallel, theory, genetic parameters, epistasis, statistics.
Polysomy in Omocestus bolivari: endophenotypic effects and suppression of nucleolar organizing region activity in the extra autosomes
Authors: Viseras Esther , Camacho Juan Pedro M.
Published: November 2014

The grasshopper Omocestus bolivari shows polysomy for the M4 autosome in the male germ line but not in the male and female soma or the female germ line. All of the polysomic males identified were mosaic for this character, so that there was interfollicular, but not intrafollicular, variation for the number of extra copies of M4. All M4 chromosomes in excess of two are heterochromatinized (h-M4) as can be deduced from their evident heteropycnosis during the first meiotic division. Some of these h-M4 chromosomes lag during meiosis and therefore form microspermatids. This occurs mainly in follicles with a single h-M4. The heritable factors which are assumed to determine mosaicism for male germ line polysomy may also play a role in reducing mean cell chiasma frequency. The h-M4 chromosomes themselves, however, raise chiasma frequency in an additive manner. The silver impregnation technique identifies the primary nucleolar organizing regions (NORs) on both the X and the M4 chromosomes, together with a series of secondary micro NORs on L2, M5, M6, and S8. The h-M4 autosomes of polysomic males, however, have no detectable nucleolar activity, which appears to be causally related to the facultative heterochromatinization of the M4 and a loss of the positive C-banding character of their nucleolar associated heterochromatin.Key words: polysomy, mosaic, heterochromatin, chiasmata.
Structure and variability of nucleolar organizer regions in Parodontidae fish
Authors: Moreira-Filho Orlando , Bertollo Luiz Antonio Carlos , Galetti Jr. Pedro Manoel
Published: November 2014

Nucleolar organizer regions (NORs) were studied in mitotic chromosomes of four species of fish of family Parodontidae: Parodon tortuosus, Apareiodon affinis, Apareiodon ibitiensis, and Apareiodon piracicabae. All four species exhibited only a single nucleolar chromosome pair in their karyotypes. Intraspecific differences were observed in the size of these chromosomes; however, these were not very clear for A. affinis and A. piracicabae, Apareiodon piracicabae exhibited two clearly visible NORs in each of the nucleolar chromosomes, which was the only configuration practically found in this species. This trait therefore predominates in a homozygous condition in the population investigated. Regions of constitutive heterochromatin adjacent to the two NORs were detected. Possible mechanisms that may have originated the two NORs are discussed.Key words: nucleolar organizing regions, fish.
Assignment of glutamate oxaloacetate transaminase to chromosome 2 and alcohol dehydrogenase to chromosome 3 of Anopheles albimanus
Authors: Narang S. , Seawright J. A. , Willis N. L.
Published: November 2014

The inheritance and linkage group assignments were determined for the two enzyme loci, glutamate oxaloacetate transaminase (Got-I) and alcohol dehydrogenase (Adh-I). of Anopheles albimanus Weidemann. Got-I was assigned to the proximal position on the genetic map of the right arm of chromosome 2, and Adh-I was mapped at the distal position on the map of the right arm of chromosome 3. Gene sequences and linkage estimates are now available for 23 mutant and enzyme loci in A. albimanus.Key words: glutamate oxaloacetate transaminase, alcohol dehydrogenase, isozyme, Anopheles albimanus, genetic map.
Genetics of reciprocal differences for quantitative characters in wheat
Authors: Patel J. D. , Bains K. S.
Published: November 2014

Reciprocal differences for days to flowering, plant height, number of grains per plant, and 100-grain weight were analysed following the analysis of 40 reciprocal generation means of a bread wheat (Triticum aestivum L. em Thell.) cross 'WG 377' × 'Sonalika.' For all traits, none of the earlier fitted models of disomic inheritance to the 21 averaged means was adequate. For number of grains per spike, responsible sources of reciprocal differences were progeny and maternal line genotypes, and maternal × paternal interaction effects. For days to flowering, in addition to these sources, maternal epistasis, maternal × progeny genotype, and cytoplasm × nuclear gene interactions were responsible. For plant height and 100-grain weight, all the sources of former two characters were important. Further, contribution of the progeny genotype was maximum and duplicate type of epistasis in the progeny genotype was observed for all characters. Neither the cytoplasmic inheritance nor the maternal effects was exclusively operating for the present material. The results have been discussed considering all the sources of reciprocal differences.Key words: Triticum aestivum, wheat, reciprocal differences, genetics, nucleocytoplasmic interactions.
Variabilité électrophorétique totale à 11 loci structuraux chez les rongeurs muridés (Muridae, Rodentia)
Authors: Iskandar Djoko , Bonhomme François
Published: November 2014

Forty-six rodent species of the Muridae family were submitted to sequential electrophoresis for the study of 11 protein loci, using 12 buffer systems which differed in pH and ionic composition. The complete set of electrophoretic conditions yielded 135 variants of which 68 were detected through a single condition. The twofold increase of revealed variants was essentially limited to intergeneric comparisons because few additional variants within genera were revealed, despite the use of several buffers. These results show that estimation of the degree of genetic differentiation among taxa at a higher level than that of the genus by standard electrophoretic data may, although of current use, lead to erroneous results.Key words: biochemical polymorphism, sequential electrophoresis, murid rodents.[Translated by the journal]
The distribution of the ribosomal RNA genes in the Triticum speltoides and Elytrigia elongata genomes
Authors: Dvořák Jan , Lassner M. W. , Kota R. S. , Chen K. C.
Published: November 2014

Triticum speltoides (Tausch) Gren. ex Richter and Elytrigia elongata (Host) Nevski have two pairs of chromosomes with nucleolus organizing regions (NORs) which are the sites of the 18S and 26S ribosomal RNA (rRNA) genes. The relationships of the T. speltoides NORs to those of T. aestivum L. were determined by hybridizing an rRNA gene probe in situ in meiotic chromosomes of hybrids T. aestivum double ditelosomics × T. speltoides. The T. speltoides NORs were shown to be, as in the B genome of wheat, in the p arms of chromosomes 1 and 6. The chromosomal distribution of the E. elongata rRNA genes was determined from restriction fragment length polymorphism of the nontranseribed spacer using restriction endonuclease digested genomic DNAs from a T. aestivum × E. elongata amphiploid, disomic substitutions, and ditelosomic additions of E. elongata chromosomes in T. aestivum. Three approximately equally abundant spacer variants, 2.4, 2.0, and 1.0 kilobases (kb) long were observed in the E. elongata genotype present in the amphiploid. The copies of the 2.4 kb variant were in the short arm of chromosome 5E. whereas the copies of the 2.0- and 1.0-kb variants were in the p arm of chromosome 6E. This homogeneity within a chromosome and contrasting heterogeneity between nonhomologous chromosomes indicates that nucleotide sequence homogenization which governs the concerted evolution of the rRNA genes in E. elongata is more efficient within a chromosome than between chromosomes.Key words: rRNA genes, spacer, in situ hybridization, concerted evolution. Triticum, Elytrigia.
Genetic linkage between malathion and dieldrin resistance in Anopheles arabiensis
Authors: Lines J. D. , Curtis C. F.
Published: November 2014

A strain of Anopheles arabiensis resistant to both malathion and dieldrin was crossed and backcrossed to a susceptible strain. The progeny were tested on each insecticide in turn. Less than 50% mortality in the second insecticide exposure among the backcross progeny indicated linkage between the resistance genes. In a backcross of A. gambiae × A. arabiensis hybrids a recombination rate of 7.5% was observed. A Y-translocation strain of A. arabiensis showed less than 2.8% recombination between the resistance genes. It is impossible to confirm the genotype of apparent recombinants using existing stocks, but the two resistance mechanisms are biochemically distinguishable. If the two genes are very closely linked, linkage disequilibrium could influence the consequences of switching to malathion spraying after dieldrin resistance has evolved.Key words: Anopheles, linkage, insecticide resistance, translocation.
Genetic and cytological maps in petunia: a sketch for chromosome VI
Authors: Maizonnier D. , Cornu A. , Farcy E.
Published: November 2014

Through mutagenesis, deficiencies, and deficient trisomics it was possible to determine the cytological location of four closely linked genes of chromosome VI in petunia (An2, Rt, Dg1, and An1). An2 lies at the distal end of the short arm, whereas Rt, Dg1, and An1 are located on the long arm. In addition, mutagenesis experiments revealed a high sensitivity to radiation or tolerance for deficiency of the short arm, in contrast with the apparent stability of the long arm. Key works: petunia, trisomy, telotrisomy, gene location, genetic mapping, cytological mapping, mutagenesis, deletion.
Factors affecting the meiotic pairing behaviour of B chromosomes in the grasshopper Eyprepocnemis plorans
Authors: Henriques-Gil N. , Arana P. , Santos J. L.
Published: November 2014

A study of the meiotic behaviour of different B-chromosome variants in the acridid grasshopper Eyprepocnemis plorans demonstrates that pairing and chiasma formation in these supernumerary chromosomes depend both on genotypic factors and on the structure of the B chromosomes themselves. Genotypic effects are evidenced by the differences in chiasma frequency which the same B-chromosome combinations show in different individuals. Structural effects can be inferred from the fact that 9 of the 14 known known B variants carry a unique site to which interstitial chiasmata are confined, whereas such a site is lacking in the other five variants.Key words: B chromosomes, C-bands, chiasma frequency, chiasma localization.
Genetic relationships between subspecies of the tsetse fly Glossina morsitans inferred from variation in mitochondrial DNA sequences
Authors: Trick Martin , Dover Gabriel A.
Published: November 2014

A 750 base pair segment of DNA from the tsetse fly Glossina morsitans morsitans was isolated by means of molecular cloning. It was shown by DNA hybridization to have substantial sequence homology with a defined region of the mitochondrial genomes of several Drosophila species. When used as a probe against DNA prepared from single tsetse flies, the cloned sequence revealed local restriction site variation between members of the G. morsitans subspecies complex. This feature was used to demonstrate maternal inheritance of the sequence in progeny of hybrid crosses and to assemble comparative restriction maps for a 3-kilobase segment of each mitochondrial genome. The data obtained from these exercises point to a higher genetic identity between G. m. morsitans and G. m. centralis than between either form and G. m. submorsitans.Key words: mitochondrial DNA, tsetse fly species, Glossina morsitans.
Complementary genes for reaction to Puccinia recondita tritici in Triticum aestivum. I. Genetic and linkage studies
Authors: Singh R. P. , McIntosh R. A.
Published: November 2014

Although confirmed instances of complementary genes for rust resistance are rare, two such genes designated A and B for seedling leaf rust resistance were identified in 'Gatcher' and certain other wheats. The two complementary genes in 'Gatcher' were separated in susceptible lines which, when intercrossed, again produced resistant progenies with the specificity of 'Gatcher.' The substitution of a chromosome 3B pair from seedling susceptible 'Hope' into seedling susceptible 'Chinese Spring' resulted in lines displaying similar leaf rust responses to 'Gatcher.' Resistant segregates occurred in segregating populations from crosses of several Sr2-bearing leaf rust susceptible wheats with 'Chinese Spring.' Hence 'Chinese Spring' carried one (A) of the complementary genes, whereas the second gene (B) was very closely linked with Sr2 (r < 0.5%) and was present in a wide range of wheats possessing Sr2. Two wheats carrying gene B lacked Sr2.Key words: leaf rust, stem rust, specificity, wheat.
Are there female heterogametic strains of Chironomus tentans Fabricius?
Authors: Martin Jon , Lee B. T. O.
Published: November 2014

Although male heterogamety is the generally accepted method of sex determination in Chironomus, female heterogamety has been reported for some strains of Chironomus tentans. Some new data, combined with a reassessment of the published data, indicate that the proposal of female heterogamety rests on inconclusive data, while male heterogamety provides an adequate explanation of sex determination in C. tentans. A cross which would unambiguously discriminate between male and female heterogamety in these strains is proposed, although it is considered unlikely that female heterogamety exists in this species.Key words: sex determination, female heterogamety, Chironomus.
Cytogenetic analysis of plants regenerated from tissue explants and mesophyll protoplasts of winter rape, Brassica napus L.
Authors: Newell C. A. , Rhoads M. L. , Bidney D. L.
Published: November 2014

Plants were regenerated from seedling tissue explants of four lines of winter rape (Brassica napus L.) including a cytoplasmic male sterile line carrying Raphanus sativus L. cytoplasm, and from leaf mesophyll protoplasts of the cytoplasmic male sterile line. Chromosome number variability was investigated in 102 regenerated plants. Mitotic root-tip cells were scored initially; those plants exhibiting mixoploidy or an altered chromosome number were reexamined at meiosis to confirm the presence of alterations in germ line cells. Plants regenerated from seedling explants included 2n = 38 diploids (87.0%) similar to the parental line, monosomics (7.8%), trisomics (2.6%), and 2n = 76 tetraploids (1.3%). The germ line number was not resolved in one mixoploid (1.3%). Protoplast-derived regenerated plants were diploid (44%), hypodiploid (20%), and tetraploid or hypotetraploid (36%). Meiotic analysis of regenerated plants showed a range of multiple chromosome associations with no plants consistently exhibiting bivalent formation only. Chromosomal alterations other than number may have been induced by culture, but could not be substantiated since multiple chromosome associations were also frequent in control plants grown from seed.Key words: plant regeneration, protoplast regeneration, Brassica napus, cytogenetics.
Genetic parameters of flax genotrophs. V. Behaviour of nuclear DNA in parental and F1 generations
Authors: Al-Saheal Y. A. , Larik A. S.
Published: November 2014

The nuclear DNA difference between large (L) and small (S) genotrophs, induced in the flax variety 'Stormont Cirrus' (PL), was investigated using Feulgen photometry. L and S genotrophs were crossed, respectively, to the PL genotype and the parental, and F1 generations were grown in greenhouse (T1) and field (T2) temperatures. Results demonstrate that (i) the DNA values show increased reversion in the crosses, compared with the parents at T1 and less reversion in the crosses, than in the parents, at T2; (ii) more reversion occurs in the PL maternal crosses than in the PL paternal crosses; and (iii) the PL genotroph possess a nuclear and a cytoplasmic factor which plays a direct part in determining nuclear DNA changes in the chromosomes of the stable genotype.Key words: rDNA, DNA amounts, genotrophs, temperature effects.
Cladistic analysis of polytene chromosome rearrangements in anopheline mosquitoes, subgenus Cellia, series Neocellia
Authors: Green C. A. , Harrison B. A. , Klein T. , Baimai V.
Published: November 2014

New data on rearrangements of ovarian polytene chromosomes from mosquitoes are presented for the following species in the series Neocellia of Anopheles (Cellia): annularis, philippinensis, nivipes, splendidus, jamesii, and ramsayi. Rearrangement has involved fixation of alternatives for paracentric inversions. Two fixed inversion differences allow for the first time the direct identification of wild-caught females of philippinensis and nivipes. There is a suggestion that the latter nominal species may include two genetic species. These data and those published for close relatives are drawn together in a cladistic analysis to suggest relationships between the species. The data are limited and total relationships are not clear within the group.Key words: cladistic analysis, polytene chromosomes, Anopheles, mosquito, speciation.
Ultrastructure and the relationship between the nucleolus and the nucleolar organizer region in Orthoptera male germ cells
Authors: Esponda P. , Rufas J. S. , Fonzo S. , Gosálvez J.
Published: November 2014

The ultrastructure of the nucleolus and the nucleolar organizer region, together with the relationships they maintain, are described in male germ cells of two species of grasshoppers. The nucleolus is multiple and appears related to a fibrillar center which seems to represent only a nontranscribing part of the organizer region. By means of serial sections, a particular relationship among the fibrillar center, the rDNA loops, and the nucleolar masses is suggested.Key words: ultrastructure, nucleolar organizers, nucleolus, Orthoptera.
Influence of the soybean male-sterile gene (ms1) on the development of the female gametophyte
Authors: Kennell John C. , Horner Harry T.
Published: November 2014

Megasporogenesis and megagametogenesis were examined in a male-sterile, female-fertile mutant (ms1) of soybean (Glycine max (L.) Merr.). Multinucleate (more than eight) megagametophytes resulted from failure of postmeiotic cytokinesis that leads to a coenomegaspore of four haploid nuclei. Fusion of some nuclei may occur. Subsequent development results in mature megagametophytes with up to four eggs, or often abortion. These results support field data that show the male-sterile ms1 gene is associated with increased frequencies of polyembryony, polyploidy, haploidy, and reduced female fertility.Key words: Glycine max, female sterility, polyembryony, polyploidy, megasporogenesis, megagametogenesis.
A cytogenetic study of subfertility in the domestic cat (Felis catus)
Authors: Berepubo N. A.
Published: November 2014

The chromosomes of cat embryos derived from three subfertile queens were studied 4 weeks postcoitum. The incidence of spontaneous chromosome anomalies was 15% and the type of abnormality observed was autosomal mosaicism. The significance of this finding and the developmental fate of the chromosomally aberrant embryos is discussed. The absence of polyploidy and (nonmosaic) autosomal trisomy, which are the most common observations in previous studies on mammalian embryos, suggests that the difference between the present observations and previous studies may be related to the difference in gestational stage studied, or to the difference in ovulatory patterns between domestic cats and other mammals. Polyploidy through ageing of the gametes is less likely in the cat than in spontaneous ovulators since ovulation in cats is induced only after coitus. It is speculated that chromosome analysis of earlier stages of embryonic development may reveal more severe forms of karyotype alteration.Key words: cytogenetics, embryos, subfertility, domestic cat.
Maintenance of genetic polymorphism under conditions of genotype-dependent growth and size-selective mortality
Authors: Desharnais Robert A. , Foltz David W. , Zouros E.
Published: November 2014

Associations between heterozygosity at one or more electrophoretically detected enzyme loci and growth rate have been reported for several species of plants and animals, including several commercially important species of finfish and shellfish. The general pattern is for heterozygotes to grow faster than homozygotes, although there is some variation in growth response even within a species. Regardless of the physiological or biochemical basis of genotype-dependent growth, polymorphism at a locus affecting growth rate in an overdominant manner may be lost if larger individuals have a greater mortality rate than smaller ones. In an exploited population, mortality of this sort is likely to result from size-selective fishing pressure. Using a continuous-time single-locus model of natural selection, we have related the maintenance of polymorphism at a locus to two measures of fishing effort: β, the legal minimum size below which there is no mortality, and f, an instantaneous mortality rate owing to fishing (above the legal minimum size). We considered two different models of fishing mortality. In model 1, fishing mortality above the legal minimum size is constant; in model 2, fishing mortality is a linear function of size (above β). Numerical analysis of model 1 indicates that maintenance of polymorphism requires either a low rate of fishing mortality or a value of β that is close to zero or close to the maximum attainable size. Analysis of model 2 gives similar results, suggesting that the conclusions are not dependent on the exact form of the mortality function.Key words: heterozygosity, growth, size, mortality.
Developmental divergence among hatchery strains of rainbow trout (Salmo gairdneri). I. Pure strains
Authors: Ferguson Moira M. , Danzmann Roy G. , Allendorf Fred W.
Published: November 2014

We compare the developmental rate of six closely related hatchery strains of rainbow trout. Hatching time, morphological analysis, and the pattern of ontogenetic change in lactate dehydrogenase, malate dehydrogenase, glucosephosphate isomerase, and phosphoglucomutase activities indicate significant differences in developmental rate between strains. There is close concordance among the different measures of developmental rate. Strains with higher levels of heterozygosity, as estimated from electrophoretic analysis of 42 loci, developed faster than less heterozygous strains. The variation in developmental rate in these closely related strains indicates that there is substantial genetic variation affecting the developmental process in rainbow trout.Key words: development rate, intraspecific variation, rainbow trout.
Developmental divergence among hatchery strains of rainbow trout (Salmo gairdneri). II. Hybrids
Authors: Ferguson Moira M. , Danzmann Roy G. , Allendorf Fred W.
Published: November 2014

The developmental rates of first generation hybrids between six closely related hatchery strains of rainbow trout are compared using hatching time, morphology, and the pattern of ontogenetic change of four enzymes. Hybrid developmental rates can not be explained by additive genetic effects. Nine of 14 hybrid types developed slower than their maternal parent. These results are consistent with a hypothesis of regulatory divergence between the hybridizing strains. Heterotic effects were observed in five hybrid groups in that hybrids developed faster than their maternal parent. A strong dominance component was observed in the reciprocal hybrids of one strain. There was no association between the degree of perturbation of hybrid developmental rates and the genetic distance between hybridizing strains. Hybrids between more distantly related strains were no more delayed in their development than those from closely related strains.Key words: developmental rate, rainbow trout, hybrids, gene regulation.
Inheritance of virulence on barley in the hybrids Ustilago aegilopsidis × U. hordei and U. aegilopsidis × U. nigra
Authors: Thomas P. L. , Huang H. -Q.
Published: November 2014

The seedling-infecting smuts of barley, Ustilago hordei and U. nigra, were hybridized with U. aegilopsidis, a smut occurring on Aegilops spp. The F1 dikaryons were virulent on the common host Agropyron tsukushiense var. transiens and produced 4–8% infection on the barley cultivar Odessa. Meiotic tetrads were isolated from the F1 teliospores, backcrossed to haploid lines of both barley smuts, and the resulting dikaryons were inoculated to seeds of 'Odessa' and barley strain M732-6965-4-1B. Virulence on 'Odessa' appeared to be under dominant, multigenic control. Virulence on M732-6965-4-1B segregated as if requiring the combined presence of recessive alleles at three unlinked loci. One or two of these loci also may control virulence on the cultivar Hannchen. Two alleles at a single locus appeared to be responsible for the presence or absence of wall ornamentation among progeny of the U. aegilopsidis × U. hordei hybrid. The ease of hybridization and the inheritance of echinulation support the view that U. aegilopsidis and U. nigra are closely related and possibly conspecific.Key words: Ustilago, barley, smut, virulence, Aegilops.
A genetic analysis of path length and pupation height in a natural population of Drosophila melanogaster
Authors: Bauer Sharon J. , Sokolowski Marla B.
Published: November 2014

Behaviour–genetic studies using laboratory strains of Drosophila are often criticized because the results cannot be generalized to natural populations. The genetic component of variation in two prepupal behaviours was studied for strains derived from a natural population of Drosophila melanogaster. These strains showed a second-chromosome based contribution to differences in path length (the distance a larva crawls in a yeasted culture dish) with the long path length phenotype dominant over the short. Differences in pupation height (the distance a larva pupates above the surface of the medium) were affected not only by the second chromosomes but also by the third pair of chromosomes. The second pair influenced the differences in pupation height threefold more than the third. Intermediate pupation heights were found in the reciprocal crosses. While path lengths could be replicated in their absolute scores over different days, pupation heights could only be replicated in their relative scores.Key words: larval behaviour, Drosophila, natural population, genetics.
Mitochondrial DNA variation in Drosophila pseudoobscura and related species in Pacific Northwest populations
Authors: Hale Lawrence R. , Beckenbach Andrew T.
Published: November 2014

We have analysed mitochondrial DNA (mtDNA) from Pacific Northwest populations of Drosophila pseudoobscura, D. persimilis, and D. miranda using six restriction enzymes. We find that HpaII restriction sites are hypervariable compared to the other enzymes used. This hypervariability allows construction of a maximum parsimony map linking each mtDNA genotype. Small insertions, possibly tandem duplications, appear to have arisen concomitantly with, or subsequent to, speciation events, perhaps within the A + T rich region. Convergence of mtDNA genotypes is also evident. Unlike findings for other populations of these species, we find little evidence of mitochondrial introgression between D. pseudoobscura and D. persimilis, despite their ability to produce fertile hybrid females.Key words: mitochondrial DNA, restriction endonucleases, Drosophila, evolution.
Hybrids of Hordeum californicum and 2x H. brevisubulatum s.l. with Agropyron caninum
Authors: Gupta P. K. , Fedak George
Published: November 2014

Two diploid Hordeum species, H. californicum (2n = 2x = 14) and H. brevisubulatum s.l. (2n = 2x = 14), were used successfully to produce hybrids with Agropyron caninum (2n = 4x = 28) through embryo rescue techniques. The floral morphology of the hybrids was intermediate between the parents in each case. Both hybrids were triploids (2n = 3x = 21), and chromosome pairing exhibited a mean of 3.86 bivalents in the hybrid with H. californicum and a mean of 5.53 bivalents in the hybrid with H. brevisubulatum. Bivalent formation was attributed to a common genome between the diploid Hordeum species and the tetraploid A. caninum. It could not be ascertained whether the difference in the two hybrids was due to a difference in the degree of homology or difference in meiotic control mechanisms.Key words: Hordeum, Agropyron, homeology, triploid, intergeneric hybrid.
Symmetrical and asymmetrical sexual isolation among laboratory strains of Drosophila ananassae
Authors: Singh Bashisth N. , Chatterjee Sujata
Published: November 2014

Male-choice experiments using five isofemale lines of Drosophila ananassae originating from different localities were performed to study sexual isolation within the species. In most of the crosses homogamic matings outnumber heterogamic ones, and deviation from randomness is statistically significant in 11 of 20 crosses. This provides evidence for positive assortative mating within D. ananassae. Isolation indices range from −0.057 to 0.555. Eleven positive isolation indices are significantly greater than zero. Both types of sexual isolation, symmetrical and asymmetrical, have been observed among different strains. Thus the present results clearly indicate that the laboratory strains of D. ananassae have developed behavioural reproductive isolation as a result of genetic divergence.Key words: Drosophila, assortive mating, sexual selection, behaviour.
The effect of increased dosage of wheat chromosomes on chromosome pairing and an analysis of the chiasma frequencies of individual wheat bivalents
Authors: Miller T. E. , Reader S. M.
Published: November 2014

By crossing the 'Chinese Spring' wheat tetrasomic series with rye, 21 different hybrid genotypes were produced, each with a single different homologous pair of wheat chromosomes. These hybrids enable the effect on chromosome pairing to be assessed for an extra dose of each of the 21 chromosomes. Significant effects were observed with eight of the chromosomes. Chiasma frequencies for each of the 21 pairs of chromosomes were also studied and the differences between the chromosomes were reported. The correlation between chromosome pairing and chiasma formation and chiasma frequency differences between bivalents and genomes are discussed.Key words: wheat, chromosome pairing, chiasma frequencies.
Chromosome banding in salmonid fish: nucleolar organizer regions in Salmo and Salvelinus
Authors: Phillips Ruth , Ihssen Peter E.
Published: November 2014

Chromosome banding patterns obtained by silver staining (Ag-NORs) were analyzed in three species of Salmo (rainbow, brown trout, and Atlantic salmon) and three species of Salvelinus (brook trout, lake trout, and arctic char). In rainbow trout and Atlantic salmon the Ag-NORs were found at the secondary constrictions of a single chromosome pair, while in brown trout the Ag-NORs were found on the short arms of one or two of the two longest subtelocentric or acrocentric chromosome pairs. The location of the Ag-NORs was multichromosomal in the three Salvelinus species, occurring on one or both members of four to six different chromosome pairs in different individuals. The Ag-NOR sites were on the short arms of some acrocentric pairs and at the telomeres of other acrocentric pairs and one or two metacentric pairs. Chromomycin A3 positive bands were found at the same sites as the Ag-NORs in all species. In the species with multichromosomal location of Ag-NORs, polymorphisms in the size and location of the NORs were extremely common, so that almost every individual fish had a different pattern of Ag-NOR sites.Key words: banding, Salmo, Salvelinus, Ag-NORs, polymorphisms, nucleolar organizer.
The meiotic and mitotic chromosomes of picture-winged Hawaiian Drosophila species. I. Drosophila grimshawi and D. cyrtoloma
Authors: Clayton Frances E.
Published: November 2014

The mitotic and meiotic chromosomes of Drosophila grimshawi and Drosophila cyrtoloma, species of the picture-wing group of Hawaiian Drosophilidae, are described. The "primitive" Drosophila karyotype of five pairs of rods and one pair of dots, found in grimshawi, is compared with the karyotype for cyrtoloma, which consists of five pairs of V-shaped and one pair of J-shaped chromosomes. Cytological material was prepared by an acetoorcein technique and by C-, G-, and N-banding methods. The rod-shaped chromosomes of grimshawi contained approximately 45% heterochromatin as determined by differential staining with Giemsa. Each chromosome of cyrtoloma consists of a euchromatic arm and a heterochromatic arm; the total heterochromatin of the diploid set averaged between 55 and 60%. These measurements approximate the amounts of satellite DNA reported for these two species. Prophase and metaphase figures from both meiotic and mitotic divisions are shown.Key words: Drosophila, chromosomes, Hawaii, meiosis, mitosis.
Male sterility in Brassica napus L. associated with an extra chromosome
Authors: Fan Z. , Tai W. , Stefansson B. R.
Published: November 2014

Male sterility was investigated in backcross populations from hybrids between Diplotaxis muralis and Brassica napus using the former as the female parent. The F1 was male sterile and low frequencies (less than 20%) of male sterile plants were obtained from subsequent backcross generations. The data did not fit any Mendelian genetic ratios. Cytological examination of pollen mother cells from 52 plants of these backcross populations indicated the presence of an extra chromosome in all 22 male sterile plants and the normal chromosome number (2n = 38) in the remaining 30 fertile plants. Thus an extra chromosome which is derived from Diplotaxis muralis appears to be the sole cause of male sterility in these backcross populations.Key words: male sterility, Brassica napus, Diplotaxis muralis.
Chromosome pairing in octoploid F1 and octoploid amphiploid hybrids between Bromus inermis and B. pumpellianus
Authors: Armstrong K. C.
Published: November 2014

Chromosome pairing in the amphiploid (8x) of 4x Bromus pumpellianus ssp. dicksonii × 4x B. inermis was compared with pairing in the F1 hybrids between natural octoploid cytotypes of B. inermis and B. pumpellianus and the octoploid parents. Predominantly bivalent pairing was found in both the amphioctoploid, octoploid F1 hybrids, and octoploid parents. Bivalent formation in the amphioctoploid could be based on chromosome differentiation between the tetraploid cytotypes of B. inermis and B. pumpellianus. These results suggest that the evolution of the octoploid cytotypes of B. inermis and B. pumpellianus could have involved hybridization of the tetraploid cytotypes.Key words: Bromus, chromosome pairing, octoploid, F1 hybrid, amphiploid.
Anther culture of a 2n pollen producing clone of Solanum phureja Juz. &Buk.
Authors: Veilleux R. E. , Booze-Daniels J. , Pehu E.
Published: November 2014

In a series of experiments, a total of 95 plants were regenerated from culture of 1416 anthers of a single genotype (PP5) of Solanum phureja that expressed a variable frequency of 2n pollen by the genetic equivalent of first division restitution. The regenerated plants included 29 monoploids (2n = x = 12), 58 diploids (2n = 2x = 24) and 8 tetraploids (2n = 4x = 48). Monoploids carrying the potential for 2n pollen formation are central to the development of a breeding scheme to construct highly heterozygous diplandroids. Segregation of tuber flesh color and tuber protein bands revealed by polyacrylamide gel electrophoresis in first and second generation anther-derived diploid plants provided evidence for both embryogenesis of 2n pollen as well as doubling of monoploid genomes as sources of anther-derived diploids. Because of variation for the same genetic markers in anther-derived tetraploids, sources other than embryogenesis of doubly restituted (4n) pollen grains were implied. An enhanced response to anther culture was noted in some anther-derived dihaploids.Key words: unreduced gametes, potato, anther culture, diplandroid, monoploid.
Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum). III. Inheritance of phenolic constituents
Authors: Pandeya Radhey S. , Court William A. , Poushinsky Greg , Dirks Victor A.
Published: November 2014

Genetic analyses of major phenolic constituents of flue-cured tobacco (Nicotiana tabacum L.), utilizing Griffing's method II model II and Hayman's Wr–Vr graphic analysis on a five-parent diallel set excluding reciprocals, were conducted in a replicated randomized block design over a 2-year period at the Delhi Research Station. The ANOVA for general and specific combining ability and Wr–Vr graphic analysis indicated genetic control for these phenolics. Additive genetic variance was the predominant contributor in the expression of chlorogenic acid and its isomers, scopoletin, scopolin, and rutin; dominance where present was in the partial dominance range. The role of nonallelic interaction was negligible for all variables except scopoletin and rutin. Tannins consisting of chlorogenic acid and its isomers were under dominant gene control, while the coumarins, scopoletin, and scopolin, and the flavonoid rutin were under recessive gene control. A considerable degree of positive pleiotropic effect was exhibited by all phenolic constituents except scopoletin where negative correlations were prevalent. Breeding procedure and choice of parents are discussed in manipulating pheolics.Key words: quantitative genetics, tobacco, Nicotiana, phenolics.
Estimation of relative DNA content in nuclei of races of Phytophthora megasperma f. sp. glycinea by quantitative fluorescence microscopy
Authors: Rutherford F. S. , Ward E. W. B.
Published: November 2014

The fluorochrome 4,6-diamidino-2-phenylindole was used as a stain for nuclear DNA in the fungus Phytophthora megasperma f. sp. glycinea. Measurements of DNA contents were made cytofluorometrically using known haploid and diploid strains of Aspergillus nidulans as standards. No significant differences between DNA levels in nine races of Phytophthora megasperma f. sp. glycinea were found. The results are consistent with genetical data that all nine races are diploid in the vegetative state.Key words: Phytophthora, ploidy, fungi, DNA content, fluorescence.
Karyotypic analysis of two durum wheat varieties
Authors: Bebeli P. J. , Kaltsikes P. J.
Published: November 2014

The karyotypes of 'Capeiti' and 'Mexicali', two durum wheat (Triticum turgidum L. var. durum) cultivars were constructed on the basis of the Giemsa banding of their chromosomes. No major differences were noted. Minor differences were as follows: chromosome 4B of 'Mexicali' has more heterochromatin than its counterpart in 'Capeiti', and chromosome 5B in 'Capeiti' has a terminal band on its long arm that is lacking in 'Mexicali', while the opposite is true for the long arm of 6B. In 'Mexicali' 6BS there is a wider band next to the secondary constriction than in 'Capeiti'.Key words: durum wheat, karyotype, C-banding, heterochromatin.
Regional patterns of polymorphisms in natural populations of Avena barbata
Authors: Rai K. N.
Published: November 2014

A detailed survey of polymorphisms at two morphological marker loci (B/b for lemma color and Ls/ls for leafsheath hairiness) was carried out in natural populations of Avena barbata from California. Based on the degrees of polymorphisms at both loci, four major regions (I, II, III, IV) were recognized. The central-north coastal region I was highly polymorphic at both loci, whereas the south-coastal region IV was monomorphic for genotype BB lsls. Inland valley region III was also largely monomorphic for the same genotype. Except region II in which founder effects seemed to have played a significant role leading to low amounts of polymorphism and large differentiations among isolated small populations, temperatures on the east–west axis, and precipitation on the north–south axis appeared to be the primary environmental variables associated with the regional patterns of polymorphisms.Key words: Avena barbata, polymorphism, environmental associations
Heritability of height growth in 10-year-old Sitka spruce
Authors: Yeh Francis C. , Rasmussen Sven
Published: November 2014

Ten-year height growth for Picea sitchensis (Bong.) Carr. was studied in a progeny test of 42 wind-pollinated families from seven stands on the northwest coast of Vancouver Island. Although stand and family-within-stand effects were significant sources of variation, 79% of the phenotypic variance in 10-year height was associated with differences among trees within family plots. Estimates of heritability ([Formula: see text], [Formula: see text], and [Formula: see text]) indicate that a combination of stand, family-within-stand, and progeny-within-family selection will be effective for a long-term breeding program to increase tree heights in Sitka spruce.Key words: Picea, heritability, quantitative.
Effect of auxins and cytokinins upon the start of meiosis in cultured anthers of rye (Secale cereale L.)
Authors: Rueda J. , Vázquez A. M.
Published: November 2014

Anthers of rye excised at premeiotic interphase were cultured in vitro on a basic medium and on a series of auxin- and cytokinin-containing media to ascertain the effect of these plant hormones upon the start of meiosis. Only in the hormone-containing media was it possible to find anthers in which pollen mother cells had started the meiotic division. The different hormones and concentrations tested exhibited a differential capacity to induce the start of meiosis, the percentages of anthers with pollen mother cells in meiosis varying from 0% in one medium to more than 60% in two other media. In some media, pollen mother cells were able to complete the whole meiotic division, while in others they were arrested at different stages of meiosis.Key words: Secale cereale, meiosis induction, anther culture, plant hormones.
The vulgare super gene, Q: its universality in durum wheat and its phenotypic effects in tetraploid and hexaploid wheats
Authors: Muramatsu Mikio
Published: November 2014

The genotype at the Q locus on chromosome 5A of Triticum durum Desf. (2n = 28, AABB), a species with keeled glumes and tough rachis, was studied by either crossing the species with, or substituting its 5A into, a hexaploid common wheat, T. aestivum (L.)Thell. ssp. vulgare (Vill.) MK. cv. Chinese Spring (2n = 42, AABBDD, QQ genotype). Contrary to the opinion of previous researchers that keeled-glumed wheats always have the spelta gene, q, the durum strains studied had a hypermorphic allele, the vulgare gene, Q. No speltoid plants appeared in the progeny of the crosses, and disomic substitution lines (2n = 2) had squareheaded (= vulgare type) spikes. Also, three doses of the long arm of 5A of durum produced compactoidy. Apparently, Q does not produce round glumes in the genetic backgrounds of most tetraploids except T. carthlicum Nevski. The phenotype conditioned by Q, which is evidently present in all free-threshing tetraploid wheats, is somewhat different at the tetraploid level from that in hexaploids. The presence of Q tends to magnify the differences in the degree of expression of certain minor characters.Key words: Triticum, phylogeny, vulgare gene, pleiotropic gene, dosage effect, interaction.
Female meiosis during oocyte maturation in Eyprepocnemis plorans (Orthoptera: Acrididae)
Authors: Henriques-Gil N. , Jones G. H. , Cano M. I. , Arana P. , Santos J. L.
Published: November 2014

The progression of meiosis from metaphase I to telophase II was followed in oocytes of Eyprepocnemis plorans that were dissected from mature females and maintained in saline solution. The durations of the various meiotic stages were assessed at three different temperatures.Key words: grasshoppers, meiosis, oocytes.
Karyotype analysis and genome relationships of 22 diploid species in the tribe Triticeae
Authors: Hsiao Catherine , Wang Richard R.-C. , Dewey Douglas R.
Published: November 2014

Karyotypes were analyzed on 24 diploid taxa (mostly perennials) belonging to eight Triticeae genera, which are defined by genome content (basic set of seven chromosomes): (i) Agropyron (P genome), (ii) Thinopyrum (J genome), (iii) Secale (R genome), (iv) Hordeum (i genome), (v) Pseudoroegneria (S genome), (vi) Psathyrostachys (N genome), (vii) Australopyrum (W genome), and (viii) Critesion (H genome). In addition to traditional karyotype preparations, the metaphase root-tip chromosomes were analyzed by an interactive microcomputer program that printed an idiogram in which chromosomes were arranged by length. Genomes, arranged by decreasing length, are R, I, P, N, J, S, H, and W (with lengths ranging from 61.29 to 39.39 μm). Almost without exception, karyotypes of species within a genus manifest a pattern that is unique to the genome. Morphologically unique genomes are useful diagnostic features in genome identification and can complement interpretation of chromosome pairing in genome analysis.Key words: Triticeae, diploid, karyotype, genome relationship.