bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of 2-μm DNA on survival and mutagenesis in Saccharomyces cerevisiae
Authors: Nestmann Earle R. , Kowbel David J. , Potter Andrew A.
Published: November 2014

Strains of Saccharomyces cerevisiae, with and without endogenous 2-μm DNA, were studied in experiments designed to determine the effect of this plasmid on survival and mutagenesis in yeast. Comparison of the two strains exposed to ultraviolet light, 4-nitroquinoline oxide, or methyl methanesulfonate (MMS), revealed that the presence of 2-μm DNA slightly enhanced survival after exposure to each agent. Spontaneous frequencies of mutations (histidine reversion, canavanine resistance, and mitochondrial petites, but not adenine auxotrophy) were reduced by the presence of 2-μm DNA. MMS-induced His+ reversion was weak, and both strains responded similarly. No difference was found between the two strains when induced forward mutation to canavanine resistance was examined. The extent of induction of mitochondrial petites was about the same in both strains. Therefore, it appears that under these experimental conditions with these mutagens, 2-μm DNA has an effect on spontaneous mutation and survival after DNA damage but not on induced mutagenesis in S. cerevisiae.Key words: Saccharomyces, plasmid, DNA (2 μm), mutagenesis.
The genetic basis of isozyme variation in the wheat stem rust fungus (Puccinia graminis tritici)
Authors: Burdon J. J. , Roelfs A. P. , Brown A. H. D.
Published: November 2014

The pattern of inheritance of isozyme alleles was examined in the F2 progeny of a sexual cross between two different physiologic races of the wheat stem rust pathogen, Puccinia graminis Pers. f. sp. tritici Eriks. &Henn. Segregation occurred at five isozyme loci (Got, Lap, Nadhd, Pgi-2 and Pgm-1). In all of these, the observed number of F2 progeny of each of the three possible isozyme phenotypes did not differ significantly from a simple 1:2:1 ratio. Joint dihybrid segregation indicated that three of the loci formed a single linkage group: Lap–Nadhd–Pgi-2.Key words: linkage, segregation.
Polytene and mitotic chromosome analysis in Ceratitis capitata (Diptera; Tephritidae)
Authors: Bedo D. G.
Published: November 2014

Polytene chromosomes were found in several larval and pupal tissues of the Medfly, Ceratitis capitata, during a search for chromosomes suitable for detailed cytological analysis. Well-banded highly polytene chromosomes, which could be adequately separated and spread, were found in trichogen cells of the spatulate superior orbital bristles of male pupae. These chromosomes proved suitable for full polytene analysis. Thoracic trichogen cells of both male and female pupae also contain useful polytene chromosomes, although they are considerably thinner and thus more difficult to analyze. Contrasting with those in pupal trichogen cells, the chromosomes in the salivary glands, Malphighian tubules, midgut, hindgut, and fat body of larvae and pupae were difficult to prepare because of high levels of ectopic pairing and chromosome fragmentation. In hindgut preparations partial separation of up to three chromosomes was achieved, but in all other tissues no useful chromosome separation was possible. In trichogen polytene cells, five banded chromosomes and a prominent heterochromatic network associated with a nucleolus are found. The mitotic chromosomes respond to C- and Q-banding and silver staining with considerable variation. This is especially so in the X chromosome, which displays an extensive array of bands following both Q-banding and silver staining. Comparison of Q-banded metaphase and polytene chromosomes demonstrates that the five autosomes are represented by conventional polytene chromosomes, while the sex chromosomes are contained in the heterochromatic net, most of which fluoresces strongly. This suggests that the Q-bands of the mitotic X chromosome are replicated to a greater extent than the nonfluorescent material in polytene cells. This investigation shows C. capitata to have excellent cytological material for both polytene and mitotic analysis.Key words: Ceratitis capitata, Medfly, chromosomes (polytene), banding (chromosome).
Cytogenetical studies in wheat. XIV. Sr8b for resistance to Puccinia graminis tritici
Authors: Singh R. P. , McIntosh R. A.
Published: November 2014

A recessive, hemizygous-ineffective gene for resistance to Puccinia graminis tritici in 'Barleta Benvenuto', 'Klein Titan', and 'Klein Cometa' was located on chromosome 6AS, was genetically independent of the 6A centromere and failed to recombine with Sr8 (r < 0.3% at P = 0.05). It was therefore designated Sr8b. The gene formerly known as Sr8 was redesignated Sr8a. Sr8b conferred adult-plant resistance to the strains used for field tests. 'Klein Cometa' possessed a second gene in chromosome 5D; this was identified as Sr30.Key words: Puccinia, Triticum, gene location, linkage, wheat, cytogenetics, rust resistance.
Cicindelid beetles without multiple sex chromosomes (Coleoptera, Caraboidea)
Authors: Serrano J. , Galiàn J. , Ortiz A.
Published: November 2014

The spermatogenesis of three species of Spanish cicindelid beetles has been studied. Megacephala euphratica has 2n = 30 + X, Cicindela paludosa has 2n = 14 + X and is polymorphic for B chromosomes, and C. littorea has 2n = 18 + X1X2X3Y. Differences in chromosome size and length, recombination index, and other cytogenetic characters are found between species. These differences suggest some evolutionary patterns for the autosomes and the heterosomes of the subfamily Cicindelinae, which are considered in relation to the systematics of this taxon.Key words: Cicindelid beetles, chromosome number, sex chromosomes.
A revised map of chromosome 15 in Gossypium hirsutum
Authors: Menzel Margaret Y. , Richmond Kenneth L.
Published: November 2014

Three translocations involving chromosome 15 (H15) in cotton, T4R;15L 1040, T11L;15L 1058a, and T15R;20R SL15, were tested against the H15 marker genes okra leaf [Formula: see text] and veins fused (vf). The latter gene was also tested against T15L;16L 2767. Duplication deficiencies monosegmental for H15 (easily recognized by their narrow distorted bacteoles) showed that [Formula: see text] is in the right (R) arm distal to the SL15 breakpoint (bp-SL15) and cannot be distal to bp-1040 or bp-1058a in the left (L) arm. Recombination frequencies between the three bp's and [Formula: see text] showed that the order is (L) bp-1058a–bp-1040–centromere–bp-SL15–[Formula: see text]. [Formula: see text] is approximately 28 cM (centi-Morgan) from the centromere. The L and R arms of H15 defined by translocations correspond, respectively, to the long and short arms defined by telosomes. Duplication deficiencies monosegmental for H15 showed that vf is not distal to either the L arm or the R arm bp's in H15. Therefore vf and the genes Lg, s, and cr, which are closely linked to vf, cannot be located on H15 as had been assumed. "Linkage group II" thus contains genes located on two different chromosomes. We suggest retaining linkage group II for Lg and genes closely linked to it and designating the group of genes on H15 linked to [Formula: see text] as linkage group XIX.Key words: cotton, translocations, linkage maps, duplication–deficiencies, okra leaf, veins fused.
Characterization and modification of heterochromatin in four species of the immigrans species group of Drosophila
Authors: Gupta J. P. , Kumar Arun
Published: November 2014

The distribution of constitutive heterochromatin in mitotic chromosomes of four species (viz., Drosophila quadrilineata de Meijere, D. immigrans Sturtevant, D. pulaua Wheeler, and D. kohkoa Wheeler) was studied using C-banding and fluorescence staining techniques. The results of this study had revealed that the heterochromatic segments detected by C-banding in the species under study were found to coincide precisely with the areas giving bright fluorescence with the two fluorochromes, Hoechst 33258 and quinacrine. This suggested the presence of A–T rich base pairs in their heterochromatin. These studies further revealed that the modification of heterochromatin caused due to the additions or deletions in particular had also played a very significant role during the differentiation of these species.Key words: heterochromatin modification, immigrans species group, Drosophila.
Inheritance of siliqua strength in Brassica campestris L. I. Studies of F2 and backcross populations
Authors: Kadkol G. P. , Halloran G. M. , Macmillan R. H.
Published: November 2014

The inheritance of siliqua strength was studied in Brassica campestris L. using F1, F2, and backcross generations of crosses between cv. Torch (shatter susceptible) and var. Yellow Sarson and var. Brown Sarson (shatter resistant) accessions. Shatter resistance (high siliqua strength) was recessive in all crosses. Crosses involving DS-17-D (var. Brown Sarson) indicated that siliqua strength is most likely controlled by two genes that show dominant epistatic interaction. Crosses of IB-5 and B-46 (both var. Yellow Sarson) each with cv. Torch indicated the likelihood of three genes controlling siliqua strength, two of which appeared to be epistatic over the third gene when dominant. In these crosses, the multivalve character appeared to be controlled by three genes, two of which were epistatic over the third gene resulting in multivalve character when the former two were recessive. Segregation for siliqua strength in the var. Yellow Sarson crosses was not independent of segregation for multivalve character.Key words: Brassica, siliqua strength, shatter resistance, Sarson.
Cytogenetic stability of aneuploid maize tissue cultures
Authors: Rhodes C. A. , Phillips R. L. , Green C. E.
Published: November 2014

Monosomic maize tissue cultures might be used to select recessive mutations of cellular traits. This strategy would avoid some of the problems encountered with haploid cultures such as lack of vigor, sterility of regenerated plants, and uncontrolled diploidization. Monosomic and other aneuploid plants were selected among progeny of W22 R/r-x1 crossed with genetic stocks containing recessive markers. The r-x1 allele induces aneuploidy at a frequency of about 15%. Immature tassels of selected plants were used to initiate totipotent tissue cultures. Plants were regenerated from the cultures over a period of 3 to 17 months after culture initiation. Meiotic karyotypes of microsporocytes and pollen sterility were analyzed in regenerated plants. At least 40% of the 161 plants regenerated from aneuploid cultures had altered karyotypes. This frequency was not related to culture age. Most alterations involved chromosome breakage rather than changes in chromosome number. Types of alterations included heteromorphic pairs (18.1%), translocations (12.5%), addition (10.6%) or loss (1.4%) of chromosomes, and genomic doubling (2.8%). Four euploid cultures, including one with a translocation, were equally unstable (49% with alterations among 115 plants). Euploid cultures gave rise to plants with translocations (12.3%), heteromorphic pairs (8.8%), and genomic doubling (29.2%), but no single chromosome additions or losses. Plants that shared a common distinctive karyotype, such as a specific translocation, were probably derived from a common cell line. Tassels with sectors of two different karyotypes were frequent in plants regenerated from aneuploid (20%) or euploid (33%) cultures. Coenocytic microsporocytes, which lacked cell walls between nuclei, were found in plants from monosomic-2, deficient-2L, and monosomic-6 cultures. Another aberration (23% of 144 regenerants) was lack of cell wall formation after the first and (or) second meiotic division, which was often followed by nuclear fusion. Karyotypic changes observed in this study rarely involved the monosomic chromosome, which means that monosomic tissue cultures could be used to select recessive mutants. Further tests would be needed to demonstrate that the selected gene resides in the monosomic chromosome.Key words: Zea mays, monosomic, trisomic, chromosome, somaclonal variation, karyotype.
Measuring segregation distortion in Drosophila melanogaster
Authors: Sharp Cecil B. , Hilliker Arthur J.
Published: November 2014

Segregation distorter (SD) chromosomes are preferentially transmitted to offspring of a male heterozygous for SD and SD+ chromosomes, as a result of the dysfunction of SD+-bearing sperm. Segregation distortion is measured by the segregation ratio k, the proportion of progeny bearing the SD chromosome. However, k is an ordinal measure and is therefore of only limited usefulness. A transformation has been developed (the k-probit transformation) that has been used to provide an interval method of measuring segregation distortion. This method has not been adequately tested as previous comparisons of observed k distributions with those predicted by the k-probit transformation have not taken the effects of binomial sampling into consideration. We have compared k distributions produced by three different SD chromosomes with the k distributions predicted by the k-probit transformation, utilizing a computer simulation model to account for binomial sampling. The results observed with two of the SD chromosomes do not agree with the predictions of the transformation. Thus we do not support the use of the k-probit transformation to provide a valid interval measure for segregation distortion.Key words: segregation distortion, Drosophila.
Severely distorted Feulgen-DNA amounts in Pinus (Coniferophytina) after nonadditive fixations as a result of meristematic self-tanning with vacuole contents
Authors: Greilhuber Johann
Published: November 2014

Highly divergent nuclear DNA amounts were obtained in Pinus mugo and Pinus cembra when meristematic tissue from root tips was fixed either with neutral formaldehyde or various nonadditive agents as methanol – acetic acid, ethanol – acetic acid, alcohols alone, Carnoy's fluid, acetone, or was directly hydrolyzed with 5 M HCl. After formaldehyde fixation, the 1C values in P. mugo and P. cembra amount to 20.16 and 24.16 pg, respectively, when calibrated against Allium cepa as internal standard, but 1C values after application of nonadditive fixatives are strongly reduced to 25–41% of the former values. This phenomenon is explained by the observation that in Pinus a large fraction of the meristematic cells contains a considerably large vacuome, whose content (probably condensed tannins) becomes immobilized after formaldehyde fixation and further on does not interfere with the Feulgen reaction, whereas after nonadditive fixations the vacuole contents extravasate and strongly tan the whole meristem and especially the nuclei. The Feulgen reaction is impaired. The tint and absorbance spectra are different in pine and Allium cepa nuclei. Pinus Feulgen-DNA values obtained after fixations other than formaldehyde must be regarded as highly distorted from the true genomic DNA content. Self-tanning as a source of methodical error in DNA content determinations by cytochemical techniques may be widespread because of the frequent occurrence of tannins in the plant kingdom.Key words: Feulgen reaction, DNA contents, tannins, Pinus, conifers.
Location of the Ph1 locus in the metaphase chromosome map and the linkage map of the 5Bq arm of wheat
Authors: Jampates R. , Dvořák J.
Published: November 2014

Heterogenetic chromosome pairing in wheat is prevented by the Ph1 locus on the q (=L) arm of chromosome 5B. Two durum wheat cv. Cappelli structural mutants with rearranged 5Bq chromosome arms were investigated to determine the location of the Ph1 locus in the metaphase map and the linkage map of the arm. One of the mutants, Cap5Bq−, has a deletion of subregion 5Bq12.3 between C-bands 5Bq12.2 and 5Bq21 and the other one, Cap5Bq+, has the same subregion duplicated. Each mutant and standard cv. Cappelli were crossed with Aegilops kotschyi, Ae. ovata, Ae. cylindrica, Ae. ventricosa, Ae. juvenalis, and "Ae. crassa 6x." Hybrids involving Cap5Bq− had higher levels of chromosome pairing than those involving cv. Cappelli, whereas those involving Cap5Bq+ had lower levels of pairing than those involving cv. Cappelli. Cap5Bq− was crossed with cv. Cappelli and the F1 was hybridized with Ae. kotschyi and Ae. ventricosa. All hybrids with the 5Bq− chromosome had a higher level of chromosome pairing than those with the standard chromosome. Cap5Bq+ was crossed with cv. Cappelli and the F1 was hybridized with Ae. kotschyi. Most hybrids with the 5Bq+ chromosome had a lower level of chromosome pairing than those with the standard chromosome. Because the difference between the means of the two populations was small (0.43 chiasmata per cell) and the distributions overlapped, the strength of the linkage between the duplication and reduced pairing could not be determined; the data, nevertheless, showed that the reduced pairing must be strongly, if not completely, linked to the duplication. It is therefore concluded that the Ph1 locus is in the euchromatic subregion 5Bq12.3, 5Bq− is a null for Ph1, and 5Bq+ has two Ph1 loci. The 5Bq+ chromosome was substituted into Triticum aestivum cv. Chinese Spring, the substitution was crossed with cv. Chinese Spring ditelosomic 5Bq, and the F1 was crossed with cv. Chinese Spring monosomic 5B. Recombination of C-bands relative to each other and the centromere was determined with the objective of determining the distribution of crossing-over along the 5Bq arm and the linkage of the subregion 5Bq12.3 with the centromere. The distibution of crossing-over was greatly distorted, most occurred in the distal region of the arm. The subregion 5Bq12.3 showed a tight linkage with the centromere, even though it is in the middle of the 5Bq arm. It is proposed to designate the cv. Cappelli Ph1− mutation as ph1c.Key words: Triticum, map distortion, homoeologous pairing, chromosome pairing, chromosome rearrangement.
The influence of fixation on the morphology of mitotic chromosomes
Authors: Dietrich Axel J. J.
Published: November 2014

It is well known that there is a strong influence of fixation, i.e., acetic methanol versus formaldehyde, on the chromosome morphology at stages of the first meiotic division. In this study the influence of both these types of fixation on the morphology of mitotic chromosomes was examined in human lymphocytes. After methanol – acetic acid (3:1) fixation, the chromosomes show the "classical" condensed shape in which it is not always possible to recognize the two sister chromatids. These chromosomes are accessible to the conventional G-, R-, and C-banding techniques. After formaldehyde fixation at a relatively high pH, the chromosomes are thinner and longer (two to six times) when compared with chromosomes following methanol – acetic acid fixation. They show a scaffold-like morphology, sometimes with a halo of thin material around it. In all cases the two sister chromatids could be recognized. This chromosome structure could be easily stained with silver, Giemsa, 4,6-diamino-2-phenyl-indole (DAPI), and fluorescein isocyanate isomere 1 (FITC). The results obtained following these stainings gave no indication to any specific chemical composition of a probable central scaffold. The scaffold-like structures were not accessible to G-, R-, or C-banding techniques. The only effect observed following these banding techniques was the disappearance of the halo of thin material around the central scaffold-like structure.Key words: chromosome structure, fixation influence, human lymphocytes.
Cytogenetic studies in gomphocerine grasshoppers. II. Chromosomal location of active nucleolar organizing regions
Authors: Cabrero Josefa , Camacho Juan Pedro M.
Published: November 2014

Nucleolar organizing region (NOR) location has been studied in 20 species of gomphocerine grasshoppers. In the 17 species with 2n (♀) = 17, the largest number carry an active NOR on the L2, L3, and X chromosomes. The M4, M5, M6, and S8 show NOR activity in some species, but the L1 and M7 do not carry a NOR in any. While almost all NORs on L2, L3, and X show primary activity, a majority of these on the M4, M5, M6, and S8 are secondary and express a nucleolus only in a minority of male meiocytes. The NORs are located preferentially at particular chromosomal sites; primary active NORs prevail in interstitial locations, while secondary active NORs predominate in paracentromeric locations. In the majority of the species analyzed in this report, primary and secondary active NORs coincide with C-bands. Euchorthippus pulvinatus is an exception; here NORs do not seem to be related to C-bands. However, the nucleolar-associated heterochromatin in this species can be demonstrated by a N-banding technique.Key words: nucleolar organizer, NOR (primary), C-bands, heterochromatin, NOR (secondary).
Rye heterochromatin. II. Characterization of a derivative from chromosome 1DS.1RL with a reduced amount of the major repeating sequence
Authors: Koebner R. M. D. , Appels R. , Shepherd K. W.
Published: November 2014

Homoeologous recombination between wheat chromosomes and the long arm of chromosome 1R of rye present in a wheat background as the wheat–rye translocation, 1DS.1RL, has been reported. During the course of this study an unexpected plant (308-17), with a recombinant phenotype, arose from a control population where homoeologous pairing was thought to be suppressed. The putative recombinant chromosome in plant 308-17 carried two seed protein loci located on 1RL (namely, the rye Glu-R1 locus and a recently discovered globulin-like marker) but appeared to lack C-banded heterochromatin. Further investigation of this apparent recombinant chromosome in progeny of 308-17 using a cloned probe for the 350 family of rye heterochromatic sequence indicated that some terminal heterochromatin was still present but in a much reduced amount. Because it appears that only the terminal region has been changed, the modified chromosome in 308-17 most likely did not arise from homoeologous recombination but rather from some form of heterochromatin loss event, possibly involving an unequal sister chromatid exchange within the terminal heterochromatin of 1RL. Sister lines to plant 308-17 carrying Glu-R1 contained a normal amount of 1RL heterochromatin.Key words: rye–wheat, heterochromatin, recombinant, unequal sister chromatid exhange.
Alien chromatin in wheat: ribosomal DNA spacer probes for detecting specific nucleolar organizer region loci introduced into wheat
Authors: Appels R. , McIntyre C. L. , Clarke B. C. , May C. E.
Published: November 2014

The structure, at the level of restriction endonuclease mapping, of rDNA spacer regions from representatives of the B, R, S, P, N, J1J2, and E genomes within the Triticeae are compared. The results indicate that the evolution of the main spacer region of rDNA units is sufficiently rapid to allow each genome to be clearly identified. The spacer regions can be successfully used to distinguish respective alien rDNA units when they are present in wheat.Key words: Triticeae, alien chromatin, molecular probes, NOR loci.
Estimating the genic and chromosomal components of reproductive isolation within and between subspecies of the grasshopper Caledia captiva
Authors: Shaw D. D. , Coates D. J. , Wilkinson P.
Published: November 2014

Previous studies have indicated that the Moreton and Torresian subspecies of the grasshopper Caledia captiva are distinguished by a series of pericentric rearrangements involving 8 of the 12 members of the genome. In addition, they show distinctive allozyme patterns with[Formula: see text]. The two taxa meet in southeast Queensland where they form a narrow hybrid zone. Experimental hybridization between the taxa reveals that the F2 generation is totally inviable and backcrosses are 53–64% inviable.A major component of inviability is correlated with the redistribution of chiasmata which occurs in F1 heterozygotes and leads to the production of novel recombinant chromosomes. However, the relative contributions of the effects of chromosomal heterozygosity versus those effects because of genic divergence could not be distinguished. The discovery that the metacentric Moreton subspecies represents the northerly limit of a continuous chromosomal cline has resolved this problem. At the southern end of the cline (Lakes Entrance), the karyotype is composed entirely of acro- and telo-centric chromosomes which are equivalent in their gross structure to the Torresian karyotype and there is no redistribution of chiasmata in (LE × TT) F1 hybrids. However, the Lakes Entrance population still retains allozymic and highly repeat DNA profiles similar to the Moreton taxon. Crosses between Moreton and Lakes Entrance, which are genically equivalent but chromosomally divergent, show 42% inviability in the F2 generation. Similarly, when the chromosomal component is removed, as in the (LE × TT) cross, F2 and backcross viabilities are improved by 46 and 21–36%, respectively.These data clearly indicate that the pericentric rearrangements which distinguish both the end points of the continuous cline and the two parapatric subspecies are involved in postmating reproductive isolation.Key words: chromosomal rearrangements, reproductive isolation, speciation, clines.
Analysis of induced homoeologous pairing in hybrids between 6x triticale ph1 mutant and Triticum aestivum L.
Authors: Jouve Nicolás , Giorgi Benito
Published: November 2014

The meiotic behaviour of three hexaploid triticale × Triticum aestivum L. hybrids having different doses of ph1 mutant alleles was investigated using C-band staining of pollen mother cells at first metaphase. D-genome chromosomes that were clearly distinguished by their small size and unbanded response to Giemsa staining were increasingly promoted to pair with the homoeologous chromosomes of the A and B genomes in the absence of Ph1 genes. However, the wheat–rye associations were not enhanced when one or two ph1 alleles were present. The distribution of meiotic configurations was significantly different for each chromosome in the ph1/ph1 hybrid. Thus, 1B did not form multivalents in this hybrid, and the remaining identified chromosomes differed significantly in the level of involvement in tri-, quadri-, or quinque-valents. The hybrids should be of value for hexaploid and wheat breeding programs.Key words: Triticale, Triticum aestivum, C-banding, ph1 mutants.
A general method for identifying correct solutions in the quantitative analysis of gene conversion data
Authors: Lamb Bernard C.
Published: November 2014

Past attempts to obtain values for meiotic parameters relating to hybrid DNA formation and the correction of mismatched bases in hybrid DNA have not given unique solutions unless various simplifying assumptions were made. A method is given for identifying correct sets of solutions after calculating the frequency of hybrid DNA formation at a heterozygous site and using the fact that closely linked sites within a locus have very similar hybrid DNA formation frequencies. The method is illustrated with simulated data and Sordaria fimicola data; it can also show up incorrect assumptions in analysis. A method is suggested for assessing the importance of double-strand gaps in producing conversions.Key words: recombination, gene conversion, quantitative analysis.
Altered regulation of c-myc expression in adenovirus-transformed cells
Authors: Braithwaite Antony W. , Fry Kathy E. , LeJeune Sue , Naora Hiroto
Published: November 2014

Expression of the oncogenes c-myc, c-raski, and p53 is studied in normal primary mouse cultures and in two adenovirus-transformed mouse cell lines. In all cases oncogene expression is measured in cells arrested in G1 (or G0 for primary cells) by serum starvation and at different times after cell cycle traverse is stimulated by addition of high serum. For primary mouse cells, c-myc mRNA levels are found to increase four- to six-fold within 1 h of serum addition and then decline by 4 h to nearly the level observed in serum-starved cells. This level is maintained throughout the remainder of the cell cycle. The early induction of c-myc is dependent on serum concentration and is independent of cell density. These results confirm and extend previous observations for primary cells. By contrast, expression of c-raski does not vary at all through the cell cycle and p53 increases with time after mitogenic stimulation. In the adenovirus-transformed cell lines, the regulation of expression of c-myc with respect to the cell cycle is altered. There is an increase in c-myc in S phase cells which is dependent on cell density and the early induction in response to serum addition as seen in primary cells is absent. Expressions of c-raski and p53 are found to show similar profiles to those observed for primary cells.Key words: cell cycle, c-myc, transformed cells.
Triple testcross analysis of F2 and irradiated F2-derived lines of Pisum sativum L.
Authors: Virk D. S. , Multani D. S. , Virk Parminder S. , Verma M. M. , Singh N. B.
Published: November 2014

The triple testcross breeding design was applied to a set of F7 and RF7 pure-breeding lines derived from normal and irradiated F2 seeds of the cross 'Bonneville' × T 163. Two phenotypically extreme lines and their F1 were used as testers in both control and irradiated materials. Epistasis was, in general, not an important component of variation. Additive component was the most important, while dominance was detected in 3 of 10 cases. The additive and dominance components in general decreased following irradiation as a result of additive and dominance effects of induced new alleles being smaller than those generated by the original alleles they replaced.Key words: triple testcross, irradiation, single seed descent, genetic anaylsis, pea.
A bread wheat (Triticum aestivum) × cultivated barley (Hordeum vulgare) hybrid with homoeologous chromosome pairing
Authors: Sethi G. S. , Finch R. A. , Miller T. E.
Published: November 2014

Triticum aestivum 'Chinese Spring' mutant ph1b lacking the major wheat homoeologous pairing prevention gene was pollinated with Hordeum vulgare line 'Tuleen 346,' a triple interchange homozygote with all chromosomes distinct from one another. Two wheat-like hybrids, one with 28 and one with 31 chromosomes, were produced. Homoeologous chromosome pairing occurred in the hybrids, but no evidence of interspecific chromosome pairing was observed. Both hybrids were sterile, but pollination of the 28-chromosome hybrid with 'Chinese Spring' pollen gave a few seeds. Within the F1 hybrids, chromosome numbers varied slightly, especially among pollen mother cells, and barley showed partial dominance of nucleolus organizer regions in somatic cells. The 31-chromosome hybrid was awned possibly indicating extra dosage of a homoeologous group-2 chromosome.Key words: wheat, barley, hybrid, homoeologous pairing.
Genetic control of meiotic chromosome pairing in tetraploid Agropyron elongatum. I. Pattern of pairing in natural and induced tetraploids and in F1 triploid hybrids
Authors: Charpentier A. , Feldman M. , Cauderon Y.
Published: November 2014

Meiotic chromosome pairing was studied in natural and induced tetraploid Agropyron elongatum, as well as in triploid hybrids between natural tetraploid and diploid cytotypes. The natural tetraploids showed a highly regular, diploid-like pairing, while the induced ones showed an average of two to three multivalents per cell. A high level of pairing was exhibited by the triploid hybrids, 4.15 bivalents and 2.82 trivalents per cell, supporting the assumption that the natural tetraploid is of an autoploid origin. Frequencies of meiotic configurations of the induced tetraploid and of the F1 triploid hybrids deviated significantly from the expected values based on a model assuming random pairing within one homologous group in autoploids: the observed data were characterized by fewer multivalents than expected, indicating a tendency towards bivalentization. This tendency is fully realized in the natural tetraploid. The presence of a pairing-control system in these autoploids, most probably a genetic one, that determines bivalent rather than multivalent pairing is suggested.Key words: Agropyron, pairing, bivalentization, tetraploid, multivalents.
Genetic modifications of dimorphic incompatibility in the Turnera ulmifolia L. complex (Turneraceae)
Authors: Shore J. S. , Barrett S. C. H.
Published: November 2014

Diploid and tetraploid populations of Turnera ulmifolia are distylous and exhibit a strong self-incompatibility system. Distyly is governed by a single locus with two alleles. Several self-compatible variants were, however, obtained and the nature and genetic control of self-compatibility was assessed using controlled crosses. The study documented the occurrence of self-compatible variants in four contrasting situations. These included the following. (i) Self-compatibility in a diploid short-styled variant. The gene(s) governing self-compatibility interact with the distyly locus and are expressed only in short-styled plants. When tetraploids carrying the genes were synthesized, self-incompatibility reappeared. (ii) Self-compatibility occurred in a cross between geographically separate diploid populations. Self-compatibility appeared sporadically in the F1. Crosses revealed that self-compatibility is likely under polygenic control. (iii) Low levels of self-compatibility occurred in a tetraploid population. Crosses revealed that self-compatibility was under polygenic control. A small response to selection for increased self-compatibility was observed, (iv) Hexaploids were synthesized from crosses between distylous diploids and tetraploids. All hexaploids obtained were long- or short-styled indicating that hexaploidy per se does not cause homostyly. A single long-styled plant showed aberrant pollen behaviour, resulting in a moderate degree of self-compatibility. All of the variants studied exhibited either aberrant pollen or stylar incompatibility responses. In no instance was the genetic control of self-compatibility solely the result of segregation at the distyly locus.Key words: Turnera, dimorphic incompatibility, polyploidy, self-compatibility, distyly.
Chromosomal location of seed storage protein genes in the genome of Elytrigia elongata
Authors: Dvořák J. , Kasarda D. D. , Dietler M. D. , Lew E.-J. L. , Anderson O. D. , Litts J. C. , Shewry P. R.
Published: November 2014

Additions of complete and telocentric chromosomes of Elytrigia elongata (Host) Nevski in Triticum aestivum L. 'Chinese Spring' were employed to assign the genes coding for seed storage proteins to chromosome arms in the E. elongata genome. Genes coding for prolamins equivalent to wheat gliadins were found on chromosome arms 1ES and 6Ep. Genes on chromosome arm 1ES, which is presumably the p arm, coded for several components with electrophoretic mobilities (lactate–PAGE) corresponding to those of β-, γ-, and ω- gliadins and those on chromosome arm 6Ep coded for two components with mobilities corresponding to those of β-gliadins. Amino acid sequencing of mixtures of prolamins from E. elongata and from E. pontica (Podp.) Holub, a species closely related to E. elongata, indicated that prolamins of these species correspond to α-type (which includes β-gliadins), γ-type, and ω-type gliadins. Restriction fragments of genomic DNAs from substitution lines of chromosome 6E of E. elongata in 'Chinese Spring' were separated electrophoretically in agarose gels and probed with a cloned α-type gliadin gene from 'Yamhill'. This Southern blot showed that chromosome 6E yields DNA fragments identical in size to those characteristic of the α-gliadin gene cluster that is on chromosome 6A of 'Chinese Spring', 'Cheyenne', and 'Yamhill'. These results indicate that structural genes for prolamins of Elytrigia are similar to those of wheat gliadins and are located on the same chromosome arms as those in Triticum species. A high molecular weight (HMW) protein likely to be a HMW glutenin subunit was located on the long arm of chromosome 1E, which presumably is the q arm; this also is in accordance with the location of HMW glutenin subunit genes in Triticum. It is concluded that the appearance of α-type gliadin genes on chromosomes of homoeologous group 6 in T. aestivum occurred prior to divergence of Triticum and Elytrigia but after the divergence of Secale, Hordeum, and the Triticum–Elytrigia lineages, since neither Secale or Hordeum appear to have α-type genes. It is, however, possible that α-type gliadin genes were deleted from the ancestors of Secale and Hordeum after divergence from the Triticum–Elytrigia lineage.Key words: Elytrigia elongata, gene location, prolamins, gliadins, wheat.
The inheritance of genetic variation in rye (Secale cereale) affecting homoeologous chromosome pairing in hybrids with bread wheat (Triticum aestivum)
Authors: Gupta P. K. , Fedak George
Published: November 2014

Chiasmata frequencies ranging from 0.07 to 10.40 per cell were recorded in 125 hybrid plants derived from wheat × F1 rye crosses. These included 89 plants belonging to 28 families from the Triticum aestivum 'Chinese Spring' × Secale cereale F1 ('Petkus' × 'Prolific') cross and 36 plants belonging to 11 families from the 'Chinese Spring' × F1 ('Prolific' × 'Puma') cross. The data were analyzed to study the inheritance of genetic variation in rye affecting homoeologous chromosome pairing. The results were particularly interesting in the former case where segregation for major genes was evident. First, in this cross, a bimodal distribution was observed and second, chiasmata frequencies ranging from 6.11 to 10.40 per cell were observed in three families but without any hybrid falling in either the range of 3.0 to 6.0 or in the range of 6.11 to 9.82, showing discontinuous distribution. It was concluded that the genetic system in 'Petkus' differs from that in 'Prolific', and that genes both with major effects and minor effects may be present, the major effects possibly resulting from complementary gene action. In the second cross involving F1 rye plants derived from 'Prolific' × 'Puma', a smaller sample gave a continuous distribution with a single mode, the chiasmata frequency never exceeding 2.70 per cell. This could be due to a difference in genetic systems found in 'Puma' and 'Petkus' since 'Prolific' was a common parent in both crosses. The genetic variation in rye observed in the present study has been compared with that known in Aegilops speltoides and it was concluded that these may be of a similar nature.Key words: Triticum, Secale, pairing regulation, homoeologous pairing.
Comportement meiotique de populations tetraploides du genre Dactylis
Authors: Guignard Gaëtan
Published: November 2014

A statistical study of four criteria applied to the genus Dactylis (Poaceae) enabled us to determine the individual meiotic behaviour of eight tetraploid populations. Those criteria were as follows: the percentage of rod and ring bivalents, the average number of tetravalents, the average number of chiasmata, and the distribution pattern of chromosomic formulas.Key words: Dactylis, populations, meiotic behavior, tetraploidy, cocksfoot.
Cytogenetic studies of interspecific hybrids between diploid species of Festuca
Authors: Morgan W. G. , Thomas Hugh , Evans M. , Borrill M.
Published: November 2014

Chromosome pairing in hybrids between diploid species of Festuca is described. The chromosome complements of the species from different taxonomic sections vary in chromosome size and DNA content. In interspecific hybrids involving species of the section Montanae there was a relationship between the difference in DNA content of the parental species and chromosome pairing in the F1 hybrids. The larger the difference between the DNA content of the parental species, the more pronounced the failure of chromosome pairing in the F1 hybrids. Factors other than divergence in genome size were also shown to have an effect on chromosome pairing in other hybrid combinations.Key words: chromosome pairing, DNA content, Festuca, hybrids (interspecific).
Differential mitotic behaviour of genetically balanced and unbalanced microspores of an interchange heterozygote of Allium triquetrum
Authors: Rickards Geoffrey K.
Published: November 2014

Genetically balanced and unbalanced microspores of an interchange heterozygote of Allium triquetrum are shown to behave differently with respect to their first pollen grain mitosis (PGMI). Two types of unbalanced microspores abort immediately prior to PGMI, while another two types are delayed in their progression through PGMI. The data presented have relevance to transmission potentials of unbalanced postmeiotic cells and estimates of their frequencies in interchange (reciprocal translocation) heterozygotes.Key words: differential behaviour, unbalanced cells, pollen grain mitosis, interchange heterozygosity.
Spontaneous mutability and colony morphology of Gibberella baccata
Authors: Lawrence E. B. , Nelson Paul E. , Toussoun T. A.
Published: November 2014

Cultural instability is a common phenomenon in the genus Fusarium. As with other species, Gibberella baccata (Fusarium lateritium) contains cultures that are less morphologically stable than others. When grown on certain media, such as potato dextrose agar, these cultures produce areas of aberrant growth (mutant patches) after 6 weeks. Single conidial cultures from these patches produce colonies different from the original culture and from each other in growth rate, colony color, aerial mycelium production, and pionnote production. Random ascospore analyses of crosses of the original morphological type to the mutant types showed there had been a one gene change in each case. Mutant patch forming and nonforming isolates of Gibberella baccata were crossed in all possible combinations, and the progeny were rated for ability to produce mutant patches. Broad sense heritability estimates for inheritance of mutant patch formation were high (60.0 to 95.9%), strongly indicating a genetic basis with a limited number of genes involved. The mutator activity of these genes appeared to be conditional and mutant patch development was dependent on the presence of some unknown factor in certain media rich in carbohydrates and other compounds.Key words: Gibberella baccata, Fusarium lateritium, colony morphology, spontaneous mutability, cultural instability.
Sperm head morphology and nuclear chromatin structure evaluated by flow cytometry in a diallel cross in mice
Authors: Ballachey B. E. , Hohenboken W. D. , Evenson D. P.
Published: November 2014

Genetic factors affecting spermatogenesis, sperm morphology, and chromatin structure in mice were estimated using a diallel cross of the inbred lines C3H/HeJ, C57BL/6J, DBA/2J, and BALB/cByJ. Flow cytometry of acridine orange stained cells was used to evaluate (i) proportions of testicular tetraploid, diploid, and haploid cells and (ii) nuclear chromatin structure of sperm, measured by resistance of chromatin to in situ acid denaturation, and quantified by the ratio of double- to single-stranded DNA (αt). Percent morphologically abnormal sperm was scored by light microscopy. Heterosis, line, maternal, and reciprocal effects, and general and specific combining abilities were estimated for body and testis weights, testicular cell proportions, sperm αt values, and percent abnormal sperm. Heterosis was important for testis weight, αt values, and percent abnormal sperm. Inbreds varied in body and testicular weights, αt values, and percent abormal sperm. Significant maternal effects were noted for several traits but could be due to sex-linked (X or Y) factors, since maternal and sex-linked effects were confounded. Although a high positive correlation existed between αt values and percent abnormal sperm, the proportion of sperm with altered chromatin structure, measured by FCM, was generally much lower than proportion of morphologically abnormal cells.Key words: mouse, spermatogenesis, chromatin structure, flow cytometry, diallel.
Role of heterochromatin during preferential 9q;22q translocation in chronic myelogenous leukemia
Authors: Verma Ram S. , Rodriguez Jorge , Babu Arvind , Chemitiganti Sundari , Coleman Morton , Silver Richard T. , Dosik Harvey
Published: November 2014

The secondary constriction region (h) of human chromosome 9 was evaluated in 55 chronic myelogenous leukemia (CML) patients with respect to its size and position. Each case was examined by C-banding and distamycin A–4,6-diamidino-2-phenylindole techniques for the expression of the h regions. When one h region of chromosome 9 was larger, it was more frequently involved in the reciprocal translocation with chromosome 22. In addition, there was a higher incidence of pericentric inversions in the h regions in the translocated chromosome 9 when compared with normal homologues. The role of the constitutive heterochromatin of chromosome 9 as a possible influencing factor during 9q;22q translocation in CML is suggested.Key words: chromosomes 9 and 22, leukemia C-banding, DA–DAPI technique, heterochromatin.
Genetics of Glossina morsitans morsitans (Diptera: Glossinidae). XII. Comparison of field-collected and laboratory-reared flies
Authors: Gooding R. H. , Jordan A. M.
Published: November 2014

Adult Glossina morsitans morsitans Westwood emerging from puparia collected at Rekometjie, Zimbabwe, were compared at 13 loci with G. m. morsitans from a closed colony at the Tsetse Research Labortory (TRL), University of Bristol, by polyacrylamide gel electrophoresis. The populations were not significantly different with respect to mean heterozygosity per locus, average effective number of alleles per locus, number of polymorphic loci, or allele frequencies at 12 loci. (The exception was Alkph.) Rare alleles at To, Est-t, and Alkph were found only in Rekometjie flies while rare alleles at G6pd and Est-2 were found only in TRL flies. No significant level of sterility was found in F1 flies produced in reciprocal crosses of Rekometjie flies with G. m. morsitans from the University of Alberta colony.Key words: Glossina, tsetse fly, isozymes, heterozygosity.
Genetic complementation by somatic hybridization between pantothenate- and adenine-requiring auxotrophs of Datura innoxia P. Mill.
Authors: Saxena Praveen K. , Mii Masahiro , King John
Published: November 2014

Auxotrophic complementation was achieved by protoplast fusion between two auxotrophic cell lines of Datura innoxia P. Mill. that required either pantothenate or adenine for their growth. Protoplast fusion was induced by polyethylene glycol enriched with calcium chloride at pH 6.8. Initial culture of fusion products in nonselective conditions increased the total number of somatic hybrids finally recovered under selective conditions. In addition to the prototrophy, the somatic hybrids regained the ability to turn green and some the ability to regenerate shoots on a cytokinin-supplemented medium. Both the parental cell lines grew as pale white callus without showing any sign of organogenesis, irrespective of the type and concentration of the cytokinin used. Approximately all the parental chromosomes (176 ± 8) were retained by the hybrid cell lines.Key words: protoplast, complementation, Datura.
Heat-shock gene expression in animal embryonic systems
Authors: Heikkila John J. , Browder L. W. , Gedamu L. , Nickells R. W. , Schultz G. A.
Published: November 2014

We have examined the expression of heat shock or stress genes in fish, echinoderm, amphibian, and mammalian embryonic systems. In a Chinook salmon embryo cell line, elevation of the incubation temperature or exposure to metal ions (e.g., cadmium and zinc) induced a set of heat-shock proteins HSPs. Transcriptional inhibitor, in vitro translation, and Northern hybridization studies suggest that fish HSP synthesis is regulated at the transcriptional level. The synthesis of HSPs during early development of Arbacia punctulata, Xenopus laevis, mouse, and rabbit is a stage-dependent phenomenon. In each of the developmental systems, HSP synthesis could not be induced until after cleavage stages. The ability of the embryo to undergo a heat-shock response (i.e., HSP synthesis) was correlated with the ability to detect HSP mRNA accumulation by either in vitro translation or Northern hybridization assays. Thus, the stage-dependent synthesis of HSPs appears to be controlled at the transcriptional level. Finally, in all of the organisms studied, the capacity to synthesize HSPs and accumulate HSP mRNA also coincides with acquisition of thermotolerance.Key words: heat shock, transcription, mRNA, actin, thermotolerance.