bluuebunny/crossref_metadata_2025 huggingface dataset:
CHROMOSOMAL INSTABILITY IN A HYBRID BETWEENHORDEUM VULGAREANDSECALE VAVILOVII
Authors: Fedak George , Nakamura Chiharu
Published: November 2014

A hybrid was obtained between Hordeum vulgare L. cv. Betzes (2n = 2x = 14) and Secale vavilovii [Nürn. (2n = 2x = 14)] in which chromosome instability was observed in somatic and meiotic tissues. In somatic tissue the chromosomes per cell varied from 7 to 24 with a mean of 19.7. Similarly in meiotic tissue the chromosome number varied from 14 to 26 with a mean of 18.3. The mean chiasma frequency was 12.9 consisting of an average Ml configuration of 0.02IV + 0.3III + 6.68II + 3.92I. It was concluded that the hybrid was derived from the union of an unreduced gamete from Betzes barley with a normal gamete from S. vavilovii.
POLYGENIC SEGREGATION WITHIN AN ISOFEMALE STRAIN OFDROSOPHILA
Authors: Thompson Jr. James N. , Hellack Jenna J.
Published: November 2014

Isofemale strains provide a sample of the genetic variation in a natural population. Phenotypically distinct chromosomes have been identified segregating within an isofemale strain of Drosophila melanogaster by extracting and progeny testing samples of single whole second and third chromosomes influencing sternopleural bristle number. Given ample opportunity for recombination to occur among linked polygenic complexes, the ability to detect clear segregation suggests that the polygenic makeup of the sampled trait may not involve large numbers of genes. Using such a sampling approach, it should be possible to quantify chromosome-level polymorphisms affecting quantitative expression. This possibility was tested using computer simulations of the progeny testing component to assess the sensitivity of the breeding program used in polygenic analysis. These computer simulations help define the optimum design for progeny testing experiments.
THE INHERITANCE OF RESISTANCE TO PUCCINIA RECONDITA IN A GROUP OF COMMON WHEAT CULTIVARS
Authors: Dyck P. L. , Samborski D. J.
Published: November 2014

The inheritance of seedling resistance to leaf rust (Puccinia recondita Rob. ex Desm.) was studied in common wheat (Triticum aestivum L.) cultivars: Terenzio, Lageadinho, PI 321999, PI 197249, CRIC 26809-68, CIRC 32125-70, 72 Hills 175 and Frontana. They have in common two complementary genes (LrT2 and LrT3) that give a variable type of leaf rust resistance. Gene LrT2 is the most effective gene. In the Thatcher background, resistance to stem rust in the adult plant stage appears to be associated with this gene. The previously reported gene from PI 58548 that gives a 2+ infection type appears to be the same as LrT2. Terenzio also carries Lr3 and Lr30 while PI 197249 has Lr3.
THE INHERITANCE OF RYE CHROMOSOMES IN EARLY GENERATIONS OF TRITICALE × WHEAT HYBRIDS
Authors: May C. E. , Appels R.
Published: November 2014

Triticales (× Triticosecale Wittmack) are being employed as a source of rye (Secale cereale L.) chromatin for the introduction of specific agronomic characters into wheat (Triticum aestivum L. em Thell.). The rye chromosomes present in plants of the first and second generations of a backcrossing program have been identified using a radioactive in situ probe which hybridizes to specific sites on the rye chromosomes. We show that homologous pairs of rye chromosomes are present by the second generation which should thereby ensure their eventual substitution. Furthermore, rye telosomes and a wheat-rye chromosome translocation involving 5RL were also observed as possibly useful modifications of the rye chromosomes in this breeding program.
2n GAMETES IN DIPLOID SOLANUM: FREQUENCY AND TYPES OF SPINDLE ABNORMALITIES
Authors: Veilleux R. E. , McHale N. A. , Lauer F. I.
Published: November 2014

Cytological disturbances resulting in 2n pollen were examined in four clones of diploid (2x = 24) Solanum phureja Juz. and Buk.; two (148-17 and 127-14) were variable and two (154-1 and B2-11) were consistently high in 2n pollen production. Three types of abnormal spindle orientation were observed at the second meiotic division: fused, tripolar, and parallel spindles (fs, tps, and ps, respectively). All four genotypes had fs. Three had tps, and ps was least frequent, occuring in two genotypes only. Cross-sections of buds revealed that all three abnormalities can occur in adjacent cells of a locule. In all genotypes, fs predominated at high levels of expression of 2n gametes. At lower levels of expression (i.e. less than 60%, which occurred only in 148-17 and 127-14), however, the frequencies of tps and ps increased. In general, there was little evidence for localization of dyads (resulting from fs or ps) or tetrads (resulting from normal divisions) within cross sections of locules, but 52.4% of all tetrads which occurred in a single locule of genotype 127-14 were found in 25% of the locular area. Cross-sections of buds revealed variation in frequency of 2n gametes among anthers (61.7 vs. 5.6% in 148-17) and between locules of an anther (73.1 vs. 90.0% in B2-11). Implications of the anatomical study were applied to current genetic theory regarding the development of 2n gametes in potato species.
THE INHERITANCE OF2nPOLLEN FORMATION IN DIPLOID ALFALFAMEDICAGO SATIVA
Authors: McCoy T. J.
Published: November 2014

The inheritance of 2n pollen formation was studied in two diploid clones of alfalfa, Medicago sativa L. The two clones consistently produced a high frequency of 2n pollen, and they also porduced good seed set when used as males in 4x-2x crosses due to the functioning of 2n(2x) pollen. For the inheritance study the two clones were crossed with diploid clones of cultivated alfalfa at the diploid level (CADL), and with several clones of diploid M. falcata. In segregating families, plants that produced a high frequency of 2n pollen were identified by good seed set when used as males in 4x-2x crosses, and/or by bimodal pollen sizes. Plants that produced 4% or more 2n pollen generally produced greater than one seed per pollination in 4x-2x crosses, and these plants were considered 2n pollen producers. Analysis of self, F1, F2and backcross (BC) families indicated 2n pollen formation was controlled by a single recessive gene, designated rp (restitution pollen). An allelism test indicated 2n pollen formation was controlled by the same recessive gene in both clones. Although there was considerable variation in the frequency of 2n pollen in rp/rp plants grown in different environments, all rp/rp plants consistently produced a significant frequency of 2n pollen (greater than 4%). Simple genetic control of 2n pollen formation has important implications in the evolution of the genus Medicago. In addition, 2n pollen formation controlled by a single gene may have potential application in the breeding of highly heterozygous tetraploids and in the efficient transfer of germplasm across ploidy levels.
ADDITIVE, NONADDITIVE AND MATERNAL GENETIC EFFECTS ON ADIPOSITY IN MICE FED DIFFERENT LEVELS OF FAT
Authors: Deodato A. de Padua , Eisen E. J. , Leatherwood J. M.
Published: November 2014

Polygenic obese (M16), nonobese (ICR) and reciprocal crossbred (M16 male × ICR female and ICR male × M16 female) mice were fed ad libitum diets containing 1, 5 or 25% fat from 3 to 10 weeks of age. Epididymal and subcutaneous fat depot weights (E, S) and depot weights as a proportion of empty body weight (E%, S%) were used as measures of adiposity at 6 and 10 weeks of age. Genetic differences in adiposity among the four populations were partitioned into average direct (a), average maternal (m) and direct heterotic (h) effects. Line M16 was greater than ICR at both 6 and 10 weeks in E (81% at 6 weeks and 114% at 10 weeks), S (82%, 73%), E% (27%, 37%) and S% (26%, 12%). Average direct genetic effects, as determined by a, accounted for 60% of the M16 vs. ICR line difference in E and S at six weeks, the remainder of the difference being due to m. The major portion of the line difference in E% and S% at 6 weeks was accounted for by m. At ten weeks of age, most of the line difference in E, S, E% and S% was due to additive direct genetic effects while the contribution of maternal genetic effects was negligible. Heterosis was sizeable for all measures of adiposity, varying from 10.8% in S% at 10 weeks to 26.8% in E at six weeks, possibly indicating the presence of directional dominance. E and E% increased significantly with the increase in dietary fat percent, but S and S% were not affected. Interactions of genotype with level of dietary fat percent were not significant for the epididymal or subcutaneous fat depot weights or proportional weights.
TRISOMIC PROGENY FROM INTERSPECIFIC HYBRIDS BETWEENHELIANTHUS MAXIMILIANIANDH.ANNUUS
Authors: Whelan Ernest D. P.
Published: November 2014

Interspecific hybrids between the diploid (2n = 34) perennial species Helianthus maximiliani Schrad. and wild H. annuus L. (2n = 34) had multivalents in meiosis. Consecutive backcrossing of the hybrids by the open-pollinated sunflower (H. annuus L.) cv. 'Saturn' resulted in rapid normalization of meiosis. However, some plants with highly modified anthers occurred and such plants were found to be diploid, whereas many plants with normal anthers and pollen shed were trisomic (2n + 1). Trisomics were first observed in two of three progenies after two crosses by 'Saturn'. Further backcrossing of trisomic females for two generations indicated about 50% megagametophyte transmission of the extra chromosome in one line and 10% in two others. Plants with a high frequency of 17 bivalents and a univalent in diplotene-MI had a higher frequency of chromosome elimination in subsequent division stages and a lower frequency of megagametophyte transmission of the extra chromosome, compared to plants having a high frequency of 16 bivalents and a trivalent. Elimination of the extra chromosome was correlated with increased pollen fertility. Primary interchange or tertiary trisomics were implicated by meiotic and fertility observations but were not identified as to type.
KARYOTYPE, SYNAPTONEMAL COMPLEXES AND POSSIBLE RECOMBINATION NODULES OF THE OOMYCETE FUNGUSSAPROLEGNIA
Authors: Tanaka Kenji , Heath I. Brent , Moens Peter B.
Published: November 2014

Pachytene nuclei of the fungus Saprolegnia ferax (Gruith.) Thuret were analyzed by serial section electron microscopy. These nuclei contained 21 synaptonemal complexes, all of which terminated at both ends on the nuclear envelope. These complexes range from 1.6 μm to 5.5 μm in length and are composed of two rather diffuse lateral elements, lack a continuous central element and contain discontinuous central nodes. These nodes occur at about 1 per μm of synaptonemal complex length, have a diameter of approximately 50 nm, are predominantly short (<200 nm) and appear to occur as multiples of a basic 50 nm length. These nodes are in many respects similar to previously reported recombination nodules. The complexes were not seen to form a bouquet stage. Based on nuclear DNA content and synaptonemal complex length, the chromosomes are calculated to contain 2C values of between 5.2 and 17.3 fg of DNA, with a mean value of 9.3 fg. Thus it seems that Saprolegnia has large chromosomes relative to other fungi and a haploid complement of 21.
COMPARATIVE THERMAL STABILITY OF PEROXIDASE ISOZYMES FROM TWO FLAX GENOTROPHS
Authors: Fieldes Mary Ann , Tyson Hugh
Published: November 2014

The thermal stability of peroxidase isozymes was examined in vitro in Linum usitatissimum L. Extracts of main stem tissues of the L and S genotrophs produced by Durrant were heat treated over a range of temperatures and times. Isozymes in treated extracts were separated electrophoretically, and peak areas for the four main anionic isozymes, together with their relative mobilities (Rms), were recorded. Peak areas supplied estimates of relative activities. Short duration treatments at 60° and 70 °C demonstrated differences in thermal stability between isozymes and produced changes in Rm. With prolonged treatment at 40 °C, the thermal stability of one isozyme differed from those of the other three. This isozyme was known to have a higher molecular weight than the others. In addition, prolonged treatment at 40 °C demonstrated increased thermal stability of the three lower molecular weight isozymes of genotroph S compared to those of L.
INHERITANCE OF YIELD AND OTHER QUANTITATIVE CHARACTERS INBRASSICA NAPUSVAR.NAPOBRASSICA
Authors: Grant I. , Harney Patricia M. , Christie B. R.
Published: November 2014

Highly significant positive heterosis was found for root length, diameter and fresh weight in F1hybrids derived in a seven-parent diallel cross of commercially available cultivars of Brassica napus L. var. napobrassica Mill. Significant general combining ability and specific combining ability effects and a preponderance of additive gene action were also noted for root length, diameter and fresh weight. The inheritance of these three traits is thought to be conditioned by additivity at the majority of loci and partial dominance at the remaining ones. Heritability estimates ranged from 0% for dry matter to 26% for root diameter.
ALLELISM OF PLEIOTROPIC DRUG RESISTANCE INSACCHAROMYCES CEREVISIAE
Authors: Saunders G. W. , Rank G. H.
Published: November 2014

Allelism of pleiotropic drug resistant (pdr) mutants was evaluated by complementation tests, linkage to chromosome-VII centromere markers and response to a partial suppressor (sur). Complementation tests were confounded by incomplete dominance and somatic segregation. Phenotypic suppression by sur was observed for all mutant and wild type alleles and thus could not be used to distinguish alleles. Five different alleles were tentatively identified by their close linkage to leu1; 88 tetrads from three factor crosses produced the following linkages — leu1 (4.7) pdr1 (17.0) trp5. Resistance of DRI 9/T7, a [cir o] strain of French origin, was not inherited as an allele of pdr but was controlled by a different pleiotropic centromere linked gene. An evaluation of published data suggest that ant1, AMY1, til1, cyh3, BOR2, and axe1 may be alleles of pdr. Thus pdr appears to be an allele that influences permeability to many inhibitors.
CYCLOPHOSPHAMIDE INDUCED IN VIVO SISTER CHROMATID EXCHANGES (SCE) IN MUS MUSCULUS. I: STRAIN DIFFERENCES AND EMPIRICAL ASSOCIATION WITH RELATIVE CHROMOSOME SIZE
Authors: Reimer Dorothy L. , Singh Shiva M.
Published: November 2014

The inducibility of sister chromatid exchanges (SCEs) by cyclophosphamide (CP) in bone marrow cells was evaluated in vivo in the three genetic strains of mice (C3H/s, C57BL/6J, and Balb/c). Female mice (10 to 12 wks old, mean = 22.9 g, SD = 3.2 g) were administered with nine hourly injections of 214.19 mg/kg 5-Bromo-2′ deoxyuridine (BrdU) followed by 0, 0.048, 0.449, 4.585 or 46.93 mg/kg CP and 4 mg/kg colcemid. SCEs were evaluated following differential staining procedures of Perry and Wolff (1974). The base-line SCEs were similar in all strains with about ten SCEs/cell. Increasing CP concentrations yielded an increased level of SCEs. Most cells showed extensive damage in CP doses exceeding 4.55 mg/kg. No SCE evaluation was possible beyond this concentration. Strain differences were evident at every dose of CP, and Balb/c was the least susceptible strain to SCE induction. F1 hybrids involving C3H/s ♂ and Balb/c ♀ showed SCE values closer to Balb/c. Data on the association between chromosome length and frequency of SCEs are provided. They empirically establish a positive correlation (r = 0.90) between the two features. Most induced SCEs were interstitially located rather than terminally positioned on the chromosome.
MARQUAGE A L'ARGENT AMMONIACAL DESCHROMOSOMES MITOTIQUES ET DES NOYAUX QUIESCENTS DE L'URODELE PLEURODELES WALTLII
Authors: Bailly Simone
Published: November 2014

Silver ammoniacal staining (Ag-As), specific for nuclear organizer regions (NORs) of mammals, has been applied to the interphase nuclei and to the mitotic chromosomes of the Triton Pleurodeles waltlii Michahelles. The banding on the chromosomes by the silver preferentially stains the pericentromeric zones where, after cold treatment, secondary constrictions appear. The metaphase karyotype (2n = 24) consists of two pairs of NORs which also stain with silver but to a lesser degree. It is also the same for the centromeres. This banding of zones other than those of the NORs is notable, not only in connection with the observations made in the case of the mammals, but also in connection with results obtained with other amphibians. An interpretation is given. The interphase nuclei also present sites of silver deposit. In the majority of cases, the sites correspond to the nucleoli. Nevertheless, supernumerary sites of deposit were apparent in a number of nuclei. This phenomenon cannot be explained clearly.[Translated by the journal]
INHERITANCE OF RESISTANCE TO HETERODERA SCHACHTII AND CHROMOSOME SEGREGATION IN TRIPLOID SUGAR BEETS
Authors: Yu M. H.
Published: November 2014

Reciprocal crosses of autotriploid nematode (Heterodera schachtii Schm.)-resistant sugar beet (Beta vulgaris L.) 6122 and diploid susceptible plants resulted in low seed set and germination. Chromosome numbers of the progeny of 6122 ranged from 18 to 38, with the majority of the progeny in 18 and 19 chromosome classes. Inheritance of nematode resistance through 6122 as female parent was 24.8% and that of the reciprocal was 5.1%. Plant 6122 probably bears only one dose of the resistance factor(s). The resistance has little effect on the survival of aneuploid gametes. The original triploid zygote was probably developed from fertilization of a first division restitution diploid megaspore bearing nematode resistance fertilized by a haploid gamete. At pachytene, trivalent associations of 6122 were not intact, with the occurrence of intercalary and terminal desynapses, heteromorphic pairings, and inversion loops. On an average 7.24III, 7.71III, and 0.09III were observed at metaphase I in microsporocytes of 6122, the autotriploid control, and triploid interspecific 4x B. vulgaris × 2x B. procumbens Chr. Sm. F1 hybrids, respectively. Meiotic irregularities occurred in over 19% of 6122 cells at AI. At TII up to six micronuclei, two AII bridges, carry-over AI bridges, and single and double restitution nuclei occurred.
DNA of AKODON (RODENTIA, CRICETIDAE). II. MOLECULAR HYBRIDIZATION OF REPETITIVE DNA SEQUENCES
Authors: Vidal-Rioja Lidia , Bianchi Nestor O. , Catala Angel , Semorile Liliana
Published: November 2014

Interspecies repetitive DNA homology was studied in akodont rodents related at generic and suprageneric levels. The homology was determined by taking the species Akodon molinae as the reference species. The 3H-DNA/DNA hybridization on filters showed a closer relationship between A. molinae and A. azarae, A. dolores and A. mollis than between A. molinae and Bolomys obscurus. These data agree with the taxonomical ranking of the species. The quantity and quality of the hybrid DNAs were measured by investigating their thermal stabilities and subsequent comparison to the results obtained on the reference species. These data indicate high similitude between the repetitive DNA of A. dolores and A. molinae. Increasing differences were shown to occur in the repetitive DNA of A. mollis, B. obscurus and A. azarae, respectively. Since these results coincide with the G-banding homologies and differ slightly from the taxonomical rank, it is speculated that the divergency between the DNA of A. molinae and A. azarae is the result of a differential process of DNA amplification which is not related to the phylogenetical distance separating the two species.
INHERITANCE OF THREE AUTOSOMAL MUTATIONS IN THE COLORADO POTATO BEETLE LEPTINOTARSA DECEMLINEATA (COLEOPTERA: CHRYSOMELDIAE)
Authors: Hsiao Catherine , Hsiao T. H.
Published: November 2014

A mutant Colorado potato beetle, Leptinotarsa decemlineata (Say), with white-body and pearl-eye was isolated. Karyotype analysis showed that the No. 2 chromosomes of the mutant are of the acrocentric race. Reciprocal crosses of the mutant with a metacentric race of the wild type revealed that both the white-body and pearl-eye are due to single autosomal recessive genes that are not allelic but segregate independently from each other. The pericentric inversion of No. 2 chromosomes is a stable mutation that followed Mendelian segregations in the F2 hybrids. Hybrids showed normal meiotic pairing. Chiasma frequency analyses indicated that the female parent influenced the recombination value of the hybrids.
WHITE FLOWER COLOR IN RAPE (BRASSICA NAPUS) ASSOCIATED WITH A RADISH (RAPHANUS SATIVUS) CHROMOSOME
Authors: Sernyk J. L. , Stefansson B. R.
Published: November 2014

The inheritance of flower color was investigated in progeny from crosses between a normal, yellow flowering rape strain (Brassica napus L.) and a white flowering strain developed at the University of Manitoba by backcrossing the white flower color from Raphanobrassica into B. napus. The chromosome number of all yellow flowering plants examined was normal (2n = 38), whereas all white flowering plants examined contained a single or a pair of small radish (Raphanus sativus L.) chromosomes each carrying a dominant gene(s) for white flower color. The homozygous white flowering rape strain was in fact an alien addition line (2n = 40) disomic for a pair of radish chromosomes. The transmission and meiotic behavior of this alien chromosome as a univalent was investigated in the progeny of crosses involving the white flowering F1 hybrid. Cytological observations of meiotic metaphase 1 indicated that the univalent should be transmitted with 24.6% of the gametes. This was in agreement with the observed transmission of 24.3% through the female gametes. Transmission through the pollen ranged from 22.1% to 0.7%, the variation in certation depending on the genetic constitution of the pistil and on the time of pollination. The vigor, fertility and true breeding nature of the white flowering strain suggested that the white flower color factor from the radish had been introgressed into the rape genome. Cytological observations were necessary to demonstrate that introgression had not taken place and to aid in the interpretation of the genetic ratios observed.
CHROMOSOME PAIRING IN HAPLOIDS OFBRASSICA OLERACEA
Authors: Armstrong K. C. , Keller W. A.
Published: November 2014

Analysis of chromosome pairing in microspore-derived haploids of broccoli, Brassica oleracea L. var. italica (2n = 18) cvs. Bravo and Green Mountain, revealed a maximum chromosome pairing at MI of 4 I + 1 II + 1 III. These data disagree with the hypothesis that diploid B. oleracea is tetrasomic for three linkage groups but indicate that it could be tetrasomic for one and hexasomic for another. It is suggested that the aneuploid series in Brassica could also be derived from a combination of modified tertiary and compensating trisomics.
DIALLEL ANALYSIS OF LOW TEMPERATURE SPROUTING ABILITY IN TOMATO POPULATIONS EVALUATED IN FIELD AND LABORATORY ENVIRONMENTS
Authors: Vos D. A. De , Hill jr. R. R. , Hepler R. W. , Garwood D. L.
Published: November 2014

Diallels with parents, F1, and F2families of tomato (Lycopersicon esculentum Mill.) were evaluated for low temperature sprouting ability in laboratory and field environments. The diallel analysis of variation among parental and F1or F2families indicated that differences attributable to additive, dominance, maternal, and residual effects were fairly consistent over laboratory and field experiments. Additive effects were the most important source of variation in both laboratory and field experiments, accounting for 46 to 85% of the total variation among families. Dominance effects specific to parents or hybrid families were significant in all laboratory experiments but accounted for less than 12% of the total variation among families. Maternal effects were the second largest source of variation among F1families (28%) and among F2families in two field experiments (8 and 18%) but accounted for less than 3% of the family variation in the F2laboratory experiments. Analysis of the Wr-Vr graph for the F2generation revealed departures from some of the assumptions required for the diallel analysis. These departures from assumptions were not detected in the analysis of the F1generation. Good agreement was obtained between field and laboratory environments. Preliminary screening for cold sprouting ability in tomatoes could be conducted in the laboratory.
Karyometric differences among nine species of the genus Chrysolina Mots. (Coleoptera, Chrysomelidae)
Authors: Petitpierre E.
Published: November 2014

The karyometric analyses of Chrysolina kuesteri with 2n = 22, C. banksi and C. obsoleta with 2n(♀) = 23, and C. affinis, C. femoralis, C. bicolor, C. herbacea, C. coerulans, and C. americana with 2n = 24, have been undertaken. The karyotype of C. kuesteri is clearly differentiated from all the remainders. Those of the other species are closely related being constituted by metacentric chromosomes, of gradually decreasing sizes. The differences among these latter karyotypes may be due to pericentric inversions, loss of the Y chromosome, and additions or deletions of chromatin.
The variance of response to selection in Tribolium castaneum
Authors: Bohn G. I. , Friars G. W. , McMillan I.
Published: November 2014

Selection for higher pupa weight in Tribolium castaneum was practised over three generations on six sets of three replications comprised of 10 families each. A check on a prediction of the variance of response to selection between replicates over generations showed that this predictor underestimated the actual variance in 13 out of 18 cases. In addition, there was a significant Spearman's rank correlation (r = 1) between the absolute value of the kurtosis of the base population and the mean standardized difference between the predicted and measured variances within sets. Taking account of the sampling variance of realized heritabilities across generations, as well as the additional variance owing to linkage disequilibrium, did not improve the fit of the predictor.
The karyotype of Isognomon alatus
Authors: Rodríguez F. , Laguarda A. , García-Cubas A.
Published: November 2014

Cytogenetic analysis of a population of Isognomon alatus Gmelin. 1971 (Pterioida-Isognomidae), from La Mancha Lagoon, Veracruz, Mexico revealed that the diploid number (2n) is 28. The chromosomes are classified as metacentric (pairs 1, 3, 4, 6), submetacentric (pairs 2, 5, 7, 8, 9, 12, and 13), subtelocentric (pair 10), and acrocentric (pairs 11 and 14). No sexual chromosomes were identified.
The genes TR, Ost, ProR, and L in natural populations of Melanoplus sanguinipes
Authors: Chapco W.
Published: November 2014

Several North American populations of the migratory grasshopper, Melanoplus sanguinipes (F.), were screened for variation at the loci, TR, Ost, ProR, and L; these are associated, respectively, with tibiae color, femoral stripe, pronotum color, and lactic acid dehydrogenase allozymes (LDH). The most common LDH allele, L2, is uniformly frequent over all sites; TR and Ost show considerable geographical variation, while allele, ProR, is rare or absent in all sampled areas. There is very little evidence of linkage disequilibrium between pairs of loci.
Abnormal meiosis in alfalfa, Medicago sativa: cytology of 2N egg and 4N pollen formation
Authors: Pfeiffer T. W. , Bingham E. T.
Published: November 2014

The cytological mechanism of 2n egg formation was studied in several diploid (2n = 2x = 16) and tetraploid (2n = 4x = 32) clones of cultivated alfalfa (Medicago sativa L.). The comparison of normal megasporogenesis with megasporogenesis that produced 2n eggs was made using an ovule clearing technique with methyl salicylate. Developmental sequences in the formation of n and 2n eggs were the same through anaphase II. Following anaphase II in 2n egg formation cytokinesis occurred only in the micropylar diad, not in the chalazal diad. Micropylar megaspores disintegrated leaving a functional unreduced megaspore of the second division restitution (SDR) type at the chalazal end. The two nuclei in the megaspore can fuse prior to the mitotic divisions or during the first two mitotic divisions. The SDR mechanism of 2n egg formation was confirmed in selected diploid clones by comparing half-tetrad analysis of 2n eggs with half-tetrad analysis of a known first division restitution (FDR) 2n pollen producer. During the study of 2n egg formation in tetraploid alfalfa, several diploid clones were found which produced octoploid (2n = 8x = 64) progeny from 4x-2x crosses. Pollen development in the diploids was normal through telophase II. Cytokinesis was absent, however, and the four telophase nuclei fused to produce a 4n pollen grain. The fusion of a 2n (2n = 4x = 32) egg and a 4n (4n = 4x = 32) pollen grain produced the octoploid progeny.
Chromosomal imbalances in Douglas-fir (Pseudotsuga menziesii)
Authors: Rehfeldt Gerald E. , Wells Stephen P. , Woo John Y.
Published: November 2014

Karyotypes of four dwarf Dougals-fir trees of similar abnormal morphology were compared with the karyotype of six trees of typical phenotype. All morphological variants were heteroploid. None exhibited the same irregularities, but all anomalies involved one of the five long metacentric chromosomes.
The variance of linkage disequilibrium between three loci in a finite population
Authors: Strobeck C. , Golding G. B.
Published: November 2014

The variance of three-locus linkage disequilibria for an equilibrium infinite alleles model is solved numerically on a computer, using identity coefficients. It is shown that the variance of three-locus linkage disequilibrium created by random drift, although smaller than the variance of two-locus linkage disequilibrium, is of the same order of magnitude. Hence third-order disequilibria are not necessarily good indications of selection. The formula for the variance of linkage disequilibrium is given when there is no recombination between the genes. This model can also be interpreted as intragenic recombination between three sites within a gene.
Evaluation of nuclear DNA content and heterochromatin changes in anther-derived dihaploids of tobacco (Nicotiana tabacum) cv. Coker 139
Authors: Dhillon Sukhraj S. , Wernsman Earl A. , Miksche Jerome P.
Published: November 2014

Nuclear DNA contents of a conventionally inbred flue-cured tobacco (Nicotiana tabacum L.) cultivar. 'Coker 139,' and two selected, doubled haploid (dihaploid) lines developed from it by anther culture and colchicine chromosome doubling were compared. The dihaploid lines had previously been shown to be lower yielding and agronomically inferior to the parental cultivar. Nuclei of leaf and root cells of the dihaploids possessed significantly higher amounts of DNA than the parental cultivar, although chromosome numbers (2n = 48) had not changed. Mean nuclear DNA content of the dihaploid lines was 10.62 pg, while nuclei of the parental cultivar contained 9.32 pg. The anther-culture process and (or) the nature of vegetative nuclei of pollen grains from which haploid plants originate have been suggested as possible contributing factors to higher DNA values. An average 12% increase in heterochromatin (condensed chromatin) in dihaploids, and significant differences in thermal denaturation of parental and dihaploid DNAs, suggest an amplification of DNA sequences during dihaploid formation.
C-banding at meiosis as a means of assessing chromosome affinities in the Triticeae
Authors: Hutchinson J. , Miller T. E. , Reader S. M.
Published: November 2014

The meiotic chromosome pairing of one 'Chinese Spring' wheat aneuhaploid (3AL) and two 'Chinese Spring' aneuploid × rye hybrids (N3A-T3B and N5B-T5D × rye) were studied. These genotypes all display higher than normal levels of pairing which were analysed with the aid of the technique of C-banding. The results show that the pattern of pairing is neither random nor of an unrestricted homoeologous nature. Pairing is more frequent between unhanded (A and D genome) chromosomes, than between either unhanded (A or D genome) and banded (B or R genome) chromosomes, or between banded (B and R genome) chromosomes.
The inheritance of resistance to Puccinia coronata and of floret characters in Avena sterilis
Authors: Wong L. S. L. , McKenzie R. I. H. , Harder D. E. , Martens J. W.
Published: November 2014

The inheritance of resistance to Puccinia coronata, awn development, lemma pubescence, and lemma color were studied in the Avena sterilis accessions CAV 4248, CAV 4656, and CAV 4904. Three independent, partially dominant genes (Pc-64, Pc-65, Pc-66) in CAV 4248, one partially dominant gene (Pc-67) in CAV 4656, and a dominant gene (Pc-68) in CAV 4904 were identified which conferred resistance to P. coronata. Genes Pc-64, Pc-65, Pc-66, Pc-67, and Pc-68 conferred resistance to 13, 8, 6, 12, and 14 races, respectively, of the 14 races of P. coronata tested. Gene Pc-68 conferred resistance to all field isolates of P. coronata collected in Canada in 1981 and was found to be closely linked or allelic to gene Pc-46. Awns and lemma pubescence were inherited monogenically in crosses with all three CAV accessions. Grey lemma color was controlled by one gene in CAV 4248 and by two genes in CAV 4656. Brown lemma color was controlled by one gene, which was closely linked or pleiotropic with the gene for lemma pubescence in CAV 4904. There was no association between crown rust resistance and the three floret characters studied.
Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum). I. Agronomic characters
Authors: Pandeya R. S. , Dirks V. A. , Poushinsky G.
Published: November 2014

A five parent diallel cross in flue-cured tobacco (Nicotiana tabacum L.) was grown over a 2-year period at the Delhi Research Station. Griffing's (1956) and Hayman's (1954) analyses indicated that general combining ability explained a high proportion of the variability of most of the agronomic characters, suggesting that additive gene action was the major component in determining the expression of these characters. This was substantiated by high narrow-sense heritability estimates. Specific combining ability components were small suggesting that dominance, if any, played a minor role. The WrVr graphic analysis of Hayman indicated a general lack of nonallelic interaction. Phenotypic, genotypic, and additive genetic correlations explained covariation among pairs of characteristics in an almost analogous manner. Implications of the genetic nature of variation in terms of practical utilization by the breeder are discussed.
The synaptonemal complex karyotype from spread spermatocytes of a dipteran (Aedes aegypti)
Authors: Wandall Annelise , Svendsen Allan
Published: November 2014

Synaptonemal complexes (SCs) from the spermatocytes of the mosquito, Aedes aegypti, were spread on a 0.3 M sucrose hypophase and analyzed in the electron microscope. The SC karyotype was similar to the one known from light microscopy of mitotic cells in both relative lengths and in centromere positions. All pachytene nuclei retained their bouquet configuration during spreading; the telomeres were polarized and clustered, and the three centromeric regions were close together. The kinetochores differentiated during pachytene, those of bivalent No. 1 (the sex bivalent) before the others. Recombination nodules were preserved in some spreads; out of 35 nodules, whose distal or proximal location on the SC arms could be determined, 27 were located in the distal one-third of the arms. No SC arm had more than one nodule.
Genetic analysis of the protein and lysine content of spring triticale
Authors: Mather D. E. , Poysa V. W.
Published: November 2014

Protein content and lysine content of protein were evaluated in the grain of 147 spring triticale lines (× Triticosecale Wittmack) derived from 15 crosses, and grown at two locations. Percent protein was negatively correlated with 1000-grain weight, grain plumpness, and yield per plant. Protein per grain was positively correlated with these traits. Lysine content of protein was negatively correlated with percent protein, protein per grain, 1000-grain weight, grain plumpness, and yield per plant. Covariate adjustment for correlated traits greatly reduced genotypic variation in the lysine content of protein. Reciprocal (cytoplasmic) differences were detected for protein per grain in some crosses. Gene effects analysis detected mainly additive gene action. Some dominance was detected for higher protein per grain. Nonallelic interaction was detected for percent protein and protein per grain in one cross each. Additive genetic variation appeared to be sufficient for improvement of grain protein content, but insufficient for improvement of lysine content by conventional breeding efforts.
Inheritance of kernel protein content in five spring wheat crosses
Authors: Sampson D. R. , Flynn D. W. , Jui P. Y.
Published: November 2014

Kernel protein content was determined in the F4 and F6 generations, grown in 1976 and 1977, of five crosses of spring wheat (Triticum aestivum L.) using infrared reflectance spectroscopy. All crosses showed continuous variation in percent protein with more or less normal frequency distributions between the two parents. Progeny means were slightly lower than the midparent values in most crosses and significantly so in the cross between the two high protein parents. The ranks of the midparent values were excellent predictors of the ranks of the progeny means. Heritability in standard units, based on intergeneration correlations, ranged from 0.25 to 0.50. These results suggest additive gene action by at least two minor genes whose individual segregation patterns were masked by larger environmental and error variances. Epistatic effects are postulated to account for the lower mean protein in the high × high cross. Two of the five crosses showed significant correlations between kernel hardness and protein content of r = 0.22 and 0.25 in the F4 but these were negative and not significant in the F6.
Electrophoretic variation in six populations of brown trout (Salmo trutta L.)
Authors: Guyomard R. , Krieg F.
Published: November 2014

Starch gel electrophoretic studies of 16 enzymes encoded by 34 Loci were performed on six brown trout populations. One new polymorphism is described at the Pmi-2 locus. Breeding data were analysed for both single and joint segregation of six loci: Aat-1, Cpk-1, G3p-2, Mdh-2, Mdh-3, and Pmi-2. All the loci are shown to segregate in simple mendelian ratios and one nonrandom joint segregation was observed, The polymorphism level, heterozygosities, and genetic distances were estimated and compared with those reported in other studies on brown trout and closely related salmonid species. The polymorphism level (25%) and average heterozygosity (9%) were high. Significant genetic distances were observed, but the average degree of differenciation between populations appeared to be small (9% of the total heterozygosity).
Translocation of zinc from vacuole to nucleus during yeast meiosis
Authors: Bilinski Carl A. , Miller John J.
Published: November 2014

A novel staining procedure employing the UV fluorochrome DAPI (4′,6-diamidino-2-phenylindole∙2HCl) and dithizone (diphenylthiocarbazone) was developed for microcytochemical determination of sites of zinc localization in Saccharomyces cerevisiae Hansen. In vegetative cells vacuolar polyphosphate bodies stained with dithizone, whereas in sporulating cells nucleoli and centriolar plaques were dithizone-positive. Hence, dithizone not only permitted localization of zinc but also indicated zinc translocation from vacuolar to nuclear compartments during differentiation from the vegetative to sporulated state.
Inheritance of resistance to Albugo candida in rape (Brassica napus L.)
Authors: Fan Z. , Rimmer S. R. , Stefansson B. R.
Published: November 2014

Canadian cultivars of Brassica napus are resistant to white rust caused by Albugo candida while many cultivars of this species grown in China are susceptible. Two Chinese lines susceptible to race 7, GCL, and 2282-9, and one Canadian resistant cultivar, 'Regent,' were chosen for a genetic study of resistance to this pathogen. Inheritance of white rust resistance is conditioned by independent dominant genes at three loci; these were designated Ac7-1, Ac7-2, and Ac7-3. The resistance is conferred by dominance at any one of the three loci and plants with recessive alleles at all loci are susceptible. Since different F2 and BC ratios were obtained for populations derived from different individual plants of 'Regent,' this 'Regent' population is not homogeneous for resistance to white rust. All 'Regent' plants appear to be homogeneous for resistance at two loci while, in addition, some may also carry resistance at a third locus.
Doubled haploids for locating polygenes
Authors: Choo T. M.
Published: November 2014

A biometrical method, making use of one or two marker genes, was proposed for use in doubled-haploid populations to locate polygenes. A polygene, if located between two closely linked marker loci, can be detected in a doubled-haploid population derived from a cross of two diploid inbred parents. In addition, the presence of additive epistasis can be detected. If the map distance between the two marker loci is so close that the frequency of double crossing-over can be neglected, then the recombination values between the polygene and either marker gene can be estimated, and the additive effect of the polygene can be determined in the absence of pleiotropy. Further, the contribution of the polygene to the quantitative trait relative to all other polygenes can be measured from the experiment if double crossing-over and epistasis are absent. Note that the proposed method can be used as an adjunct to haploid breeding routines and other genetical experiments.
Mating frequency in male Japanese quail: crosses among selected and unselected lines
Authors: Bernon D. E. , Siegel P. B.
Published: November 2014

The genetics of mating behavior in Japanese quail was investigated in replicated lines selected for high or low number of completed matings and the random bred control which served as the base population for the selected lines. Comparisons involved the parental lines, F1, F2, and backcross generations. Results indicate that mating frequency is influenced by additive and nonadditive genetic variation with the former being the primary heritable influence. The relationships between mating behavior, cloacal gland size, and relative aggressiveness suggest that selection for mating frequency influences factors commonly affecting these traits.
The use of two-dimensional electrophoresis to detect mutations induced in mouse spermatogonia by ethylnitrosourea
Authors: Marshall R. R. , Raj A. S. , Grant F. J. , Heddle J. A.
Published: November 2014

Two-dimensional electrophoresis should, in theory, be a suitable method for the measurement of induced mutation rates in the germ cells of mice. Not only can the polypeptide products of a large numer of genes be resolved on a single gel but the detection of mutations which lead to proteins with altered electrophoretic properties (but not necessarily altered function) is possible. Our attempts to apply two-dimensional electrophoresis to the detection of mutation in vivo have involved three stages: (i) the rapid production of gels of high resolution and reproducibility; (ii) the identification of eight interstrain protein variants and demonstration of their simple genetic basis; and (iii) a pilot experiment using the powerful germ-cell mutagen ethylnitrosourea. It was found that although interstrain protein variants could be detected and shown to be inherited in a codominant manner, induced variants were rarely detected even on high quality gels. Only 2 variants were detected among 67 offspring of male mice treated with 150 mg/kg ethylnitrosourea. This represented a mutation rate of 0.88 × 10−4 mutations per locus per gamete.
Chromosome pairing in female and male diploid and polyploid anurans (Amphibia) from South America
Authors: Rahn I. M. , Martinez A.
Published: November 2014

Chromosome pairing in females and males of diploid (2n = 22) and tetraploid (2n = 44) Odontophrynus americanus and diploid Ceratophrys cranwelli (2n = 26) and tetraploid C. ornata (2n = 104) showed that diploid females formed more chiasmata per paired arm than diploid males and polyploids of both sexes. There was a reduction in the level of recombination in female polyploids by forming multivalents with terminal chiasmata. The reduction reflected a change in the genetic control of pairing in females after polyploidization.
Analysis of yield factors in segregating populations and their implications in selection of flax (Linum usitatissimum)
Authors: Rao S. K. , Singh S. P.
Published: November 2014

Correlation coefficients were calculated in all possible combinations between days to maturity, plant height, number of capsules, primary branches, secondary branches, average number of seeds per capsule, 1000-seed weight, and seed yield per plant in 48 F3 populations of flax (Linum usitatissimum L.). None of these attributes had negative association with seed yield. The majority of the yield components had a strong positive association with seed yield and the correlation coefficient of plant height with seed yield was negligible. Multiple regression analysis revealed that the regression equation involving number of secondary branches and number of capsules per plant had efficient prediction power. Path analysis studies also revealed that number of capsules followed by secondary branches and 1000-seed weight were the major components influencing seed yield. Selection indices based on primary branches, secondary branches, number of capsules, 1000-seed weight, and seed yield per plant were 203.83% superior to direct selection for seed yield.
Confidence intervals of genetic parameters estimated from progeny test experiments in plant breeding
Authors: Tai G. C. C.
Published: November 2014

This paper attempts to establish confidence intervals for five genetic parameters obtained from progeny test experiments. The influence of numbers of replicates and genotypes used in an experiment on the precision of estimating genetic parameters is discussed based on the structure of the intervals. Data of a progeny test experiment of the potato are then analyzed for determining a suitable selection scheme for quantitative traits in a breeding program.
The relationships of the M and Mu genomes of Triticum
Authors: Kimber G. , Pignone D. , Sallee P. J.
Published: November 2014

Triploid, tetraploid, and pentaploid hybrids involving M and Mu genome species were examined for meiotic chromosome pairing. Values of the relative affinity of the genomes involved were calculated and it is concluded that there is no preferential pairing of the M and Mu genomes. Consequently it is suggested that the Mu genome of Triticum uniaristatum be changed to Un.
Cytogenetic characteristics of wheat plants regenerated from anther calli of 'Centurk'
Authors: Kudirka Dalia T. , Schaeffer Gideon W. , Baenziger P. Stephen
Published: November 2014

Plants were recovered from 10 different calli derived through anther culture of Triticum aestivum L. em Thell (cv. 'Centurk'). Chromosome counts and estimates of ploidy level were made on cells from roots of these developing plants. Plants with polyhaploid cells were regenerated from all calli indicating that they were of microspore origin. Three populations of plants were recognized: first, those that were polyhaploid and euploid; second, those that were almost totally polyhaploid but aneuploid; and third, those plants which were largely hexaploid with some cells reflecting spontaneous chromosome doubling. Aneuploid cells with corresponding polyhaploid and hexaploid chromosome numbers in root-tip cells among plants regenerated from a number of calli were taken to indicate that these cells were doubled haploids and not hexaploid cells of the anther wall. Mixoploid plants were regenerated from secondary calli in which chromosome doubling was known to have been induced at the callus stage. The presence of individual mixoploid root tips in these plants was assumed to indicate that individual organs of a plant may arise from several cells of a callus.