bluuebunny/crossref_metadata_2025 huggingface dataset:
Meiosis in Drosophila melanogaster. V. Univalent behavior in In(1)sc4Lsc8R/BsY males
Authors: Lin H-P. P. , Ault J. G. , Kimble M. , Church K.
Published: November 2014

Univalent behavior during meiosis has been examined in Drosophila melanogaster males possessing the In(1)sc4Lsc8R X chromosome using light microscopy and serial section electron microscopy. Males from two stocks, displaying high (0.40) and low (0.14) frequencies of sex chromosome nondisjunction, have been investigated. The results demonstrate that (i) sex chromosomes are more intimately paired during prometaphase 1 in males from the low nondisjunction stock than in males from the high nondisjunction stock, and (ii) the univalents are distributed to the poles in an unbiased manner during meiosis rather than by directed segregation of both univalents to the same pole as previously determined for other In(1)sc4Lsc8R/Y males. Kewords: Drosophila melanogaster, meiosis, univalent behavior, In(1)sc4Lsc8R/BsY males.
Linear orientation of trivalents and quadrivalents in late metaphase I pollen mother cells of pearl millet
Authors: Rao P. S. R. L. Narasinga , Sybenga J.
Published: November 2014

Robertsonian trivalents, trisomic trivalents, and tetrasomic ring quadrivalants showed linear or indifferent orientation frequencies at late metaphase I of 1/3. This fits a model assuming sequential centromere activation in the multivalent with random order of activation and sufficiently long interval to permit stable coorientation of any two early centromeres before the following centromere is activated. A late centromere trapped between two coorienting early ones is prevented from orientation. Reorientation in pearl millet, when it occurs, is late in these configurations. Chain quadrivalents have less linear but more indifferent orientations than the expected 1/6 and 1/3, respectively. Possible reasons for this are given. For rye the situation is very different: linear orientation of Robertsonian trivalents is practically absent, presumably owing to insufficiently long intervals between centromere activations, and to early reorientation. A reduction in interval length between centromere activations is assumed to accompany the stabilization of autotretraploids.Key words: pearl millet, trivalents, quadrivalents, centromere activation, chromosome orientation.
Factors distinguishing couples at risk for nondisjunction
Authors: Rudd Noreen L. , Hoar David I. , Martin Renee H. , Kemp Dorothy , Dimnik Leo
Published: November 2014

Micronucleus frequencies were determined on 24 young parents of trisomic infants, 21 individuals with recurrent unexplained abortions, and 42 control individuals with proven reproductive success. In addition to measurements of spontaneous micronucleus frequencies, mitomycin C induced frequencies were determined at two doses (2.5 and 5.0 ng/mL). Using the 95% confidence limits established from control data as an arbitrary upper limit, 16 of 24 parents of trisomics and 5 of 21 recurrent aborters were detected by the micronucleus assay to above this cutoff. The effects of sex, age, pregnancy status, and a variety of environmental exposures were studied by comparing the micronucleus frequencies of the exposed and unexposed populations. The data suggested that vitamins were associated with a lower micronucleus frequency and tea drinking with an increased micronucleus frequency in parents of trisomics, an effect not seen in controls. These results suggest that a biologic basis for nondisjunction may be associated with elevation in spontaneous and induced micronuclei. In addition, tea and vitamins may modulate micronucleus frequencies in parents of trisomics who appear to be more sensitive to these influences than the controls.Key words: micronuclei, trisomy, abortion, nondisjunction, mutagens.
Heterochromatin variation in the sex chromosomes in Thailand populations of Anopheles dirus A (Diptera: Culicidae)
Authors: Baimai V. , Andre R. G. , Harrison B. A.
Published: November 2014

Analysis of larval ganglion mitotic chromosomes of 63 strains of Anopheles dirus A from six different localities in Thailand has revealed polymorphism in the sex chromosomes with respect to the amount of constitutive heterochromatin they contain. Three forms of X and two forms of Y have been detected in wild population samples.Key words: Anopheles, chromosome polymorphism, constitutive heterochromatin, sex chromosomes, speciation.
Use of meiotic analysis to describe genomic affinities in Medicago
Authors: Smith S. E.
Published: November 2014

Numerical methods of meiotic analysis were used to describe genomic affinities in triploid Medicago hybrids. No differences in affinity were observed among the genomes of M. sativa subsp. sativa, M. sativa subsp. caerulea, and M. falcata. This study establishes the feasibility of using meiotic analysis in cytotaxonomic studies in Medicago.Key words: alfalfa, chromosome pairing, cytotaxonomy, numerical analysis.
Effect of ozone on prophage induction in different strains of Escherichia coli K-12 lysogenic for lambda
Authors: L'Hérault Pierre , Chung Young Sup
Published: November 2014

Ozone was tested for its effect upon induction of lambda prophage in two different strains of Escherichia coli K-12. Based on the induction index and when compared to ultraviolet light, ozone appeared to be a weak, if any at all, inducer of the lytic cycle in E. coli. This is in agreement with other studies which have suggested that this agent is a weak inducer of the SOS functions.Key words: SOS functions, ultraviolet light, mutagen, ozone.
Weak male-determining genes and female heterogamety in Chironomus tentans
Authors: Feraday Ray
Published: November 2014

Female heterogamety in the midge Chironomus tentans has been previously reported and attributed to a dominant female determiner. Published results are not consistent with the interpretation, and the female heterogamety, if any, can be better explained by a model involving a weakened male determiner. Suggestions are made for crosses between populations with different sex-determining mechanisms that would discriminate between models for the evolution of female heterogamety, and serve to determine whether indeed female development is the norm in the absence of any parental sex chromosomes.Key words: Chironomus, heterogamety, sex determination, sex chromosome.
The "reindeer" mutation and a revision of linkage groups V and X in the flour beetle, Tribolium castaneum
Authors: Dawson Peter S.
Published: November 2014

Reindeer (Rd) is a dominant mutation affecting antenna morphology in the tenebrionid flour beetle, Tribolium castaneum. In contrast with most dominant mutants previously described for this species, homozygotes are fully viable, thus making Rd very useful for genetic studies. Rd is tentatively assigned to either linkage group IX or X. Abbreviated appendages (aa), formerly placed in linkage group X, is reassigned to linkage group V on the basis of demonstrated linkage to jet (j).Key words: Tribolium, mutation Rd, linkage, antenna morphology.
The synaptonemal complex: does it have contractile proteins?
Authors: Spyropoulos B. , Moens P. B.
Published: November 2014

Actin and myosin are commonly involved in cell motility systems. This study attempts to identify these two proteins in the synaptonemal complex (SC), a nuclear organelle associated with chromosome pairing during meiotic prophase. The several experimental approaches reported here give no evidence of SC staining with either anti-myosin or anti-actin antibodies. These findings differ from those of other reportings.Key words: synaptonemal complex, immunohistochemistry, contractile proteins, myosin, actin.
Triple chromosome pairing in an aneuploid bull spermatocyte
Authors: Dollin A. E. , Murray J. D.
Published: November 2014

A triple synaptonemal complex was observed between three midsized chromosomes in an aneuploid bull spermatocyte. Fifteen other spermatocytes examined from the same animal displayed normal chromosome complements and pairing. This is the second case reported of triple synapsis in a mammal and the first case in an apparently normal individual.Key words: synaptonemal complex, triple synapsis, cattle, meiosis.
Haploidy in preattachment bovine embryos
Authors: King W. A. , Picard L.
Published: November 2014

Four of twenty-four bovine embryos (day 5–7) subjected to chromosome analysis had haploid cells in metaphase. Two were clearly n/2n. The origin of the haploid cells was determined to be male in two embryos, owing to the presence of a Y chromosome or a male marker chromosome suggesting spermatozoa in division.Key words: embryo, bovine, chromosomes, haploid, polyspermia.
Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum L.). II. Certain physical and chemical characters
Authors: Pandeya R. S. , Dirks V. A. , Poushinsky G. , Zilkey B. F.
Published: November 2014

Genetic analyses of flue-cured tobacco leaf physical characteristics (percent lamina, lamina weight, and filling value) and chemical characteristics (percent total alkaloids, reducing sugars, nitrogen, ash, and cellulose) were conducted on a five parent diallel set (excluding reciprocals) evaluated at the Delhi Research Station in a randomized block design over a 2-year period. The ANOVA indicated that there was variance associated with the genetic source for all characteristics except filling value. Griffing's analysis for variances owing to general and specific combining abilities suggested additive genetic variance as the main source of genetic variation. Variances owing to specific combining ability for all traits were exceeded by the variance of the estimates indicating dominance to be of no major consequence in the expression of these physical and chemical traits. Total alkaloids and percent nitrogen expressed maximum heritability, and Wr–Vr graphs supported the conclusions. Parental diversity was evident from the scatter of array points and graphic analysis also indicated lack of dominance. Examination of pleiotropic effects revealed that traits related positively with alkaloids and nitrogen were negatively correlated with carbohydrate fractions such as reducing sugars and cellulose.Key words: tobacco, heritability, dominance, additive effects.
Genetic considerations in the effects of ethanol in mice. I. Genotype-dependent alterations in alcohol dehydrogenase activity
Authors: Wang Caroline H. , Singh Shiva M.
Published: November 2014

Most genetic studies on individual and racial differences in sensitivity to alcohol intoxication have concentrated on genetic variations associated with structural genes for the enzymes involved in alcohol metabolism, including alcohol dehydrogenase (ADH; E.C. 1.1.1.1). We studied the ethanol-induced regulation of ADH following chronic administration of ethanol in mice. Newly weaned males from six inbred strains (BALB/c, C3H/HeSnJ, C3H/S, C57BL/6J, S.W., and 129/ReJ) were subjected to ethanol administration. Alterations in the level of liver ADH activity, relative to matched littermate controls, were evaluated. The change in ADH activity was found to be strain (genotype) specific, which may explain the contradictory results in the literature. Strains which showed induction of ADH activity, in general, reflected a strain-specific time-dependent profile. Strains which showed repression, however, were independent in the degree of repression to the duration of ethanol exposure. Such variable, ethanol-induced regulatory responses (induction/repression) in ADH activity of different genotypes may account for individual and population variations in response to alcohol. Additional work, however, is needed to establish the molecular bases of ADH inducibility and its specific role in relative susceptibility to alcohols.Key words: alcohol dehydrogenase, mice, ethanol effects.
Spermatogenic delay and increased chiasma frequency in T70H/+ male mice with hydroxyurea–Trenimon limited spermatocyte populations
Authors: Wauben-Penris P. J. J. , Meel G. P. J. M. van , Boer P. de
Published: November 2014

T(1;13)70H/+ male mice were treated with hydroxyurea (HU) and Trenimon (T). This karyotype offers excellent possibilities for estimating number and position of chiasmata and segregation in meiotic anaphase I. By their cell-killing action during spermatogenesis, HU and T produce large gaps in the spermatogenic line. The surviving population between the gaps was analysed at diakinesis – metaphase I and metaphase II. We found by autoradiography a considerable retardation of the development from resting primary spermatocytes (RPS) to metaphase I and II as compared to untreated T70H/+ males. Furthermore we found increased chiasma frequencies in diakinesis – metaphase I (MI) and reduced nondisjunction frequencies at anaphse I as a result of the treatments applied. The latter effect could not be explained by the increased chiasma frequency.Key words: translocation, spermatogenesis, chiasmata, segregation, mouse, hydroxyurea.
The maintenance of polymorphism owing to differences in developmental time and competition
Authors: Williams Scott M.
Published: November 2014

The effect of developmental time on the maintenance of an enzyme polymorphism is analyzed under the assumption that competition exists for a reproductively essential resource. Specifically, in laboratory vials Drosophila compete for oviposition and pupation sites. This system of competition serves as a prototype for the model with late-eclosing individuals being excluded from the reproductive pool. Two mating behaviors are modelled: (i) mating is with individuals from only the same cohort group and occurs only once, and (ii) mating is with all individuals that have eclosed up to that time and occurs daily. Numerical analyses are done on both mating structures using data from Drosophila mercatorum. The simulations show that mating structure and initial conditions do not affect the equilibrium genotype frequencies, but that slight changes in the level of competition can dramatically alter the equilibrium values.Key words: enzyme polymorphism, developmental time, oviposition.
Environmental monitoring for genotoxicity: in vivo sister chromatid exchange in the house mouse (Mus musculus)
Authors: Nayak B. N. , Petras M. L.
Published: November 2014

Sister chromatid exchange (SCE) values were determined in bone marrow cells isolated from mouse (Mus musculus) femurs after injections of 5-bromo-2′-deoxyuridine (BrdU) and 5-fluorodeoxyuridine (FrdU). Male mice of C3H/J, C57BL/6J, and DBA/2 strains maintained in the laboratory gave mean SCE values of 3.42 ± 0.07, 3.62 ± 0.08, and 3.97 ± 0.13, respectively. Males obtained from natural populations of southwestern Ontario had a higher mean SCE value (6.02 ± 0.16), as did inbred males maintained in outdoor enclosures for at least 3 weeks (5.07 ± 0.22). Wild mice housed in the laboratory for 9 months or longer had SCE values similar to laboratory bred mice (3.46 ± 0.05). The SCE values in wild-caught mice were inversely proportional (r = −0.49) to the distance between the sites where these animals were collected and the nearest major industrial center. Based on these results, SCE analysis in mice is proposed as a possible first-line monitoring procedure for the detection of general changes in environmental genotoxicity.Key words: environmental genotoxicity, sister chromatid exchange, bone marrow cells, BrdU, FrdU, mouse.
Changes in mean, variance, and covariation among agronomic traits in successive backcross generations of interspecific matings (Avena sativa L. × A. sterilis L.) of oats
Authors: Takeda K. , Bailey T. B. , Frey K. J.
Published: November 2014

F2-derived lines from BC0 through BC5 of eight Avena sativa × A. sterilis matings were evaluated for days to heading, plant height, biomass, grain yield, straw yield, harvest index, vegetative growth rate, and unit straw weight. The, A. sativa lines were used as the recurrent parents in all backcrosses. The evaluation experiment was conducted in a randomized-block design with two replicates and microplots each sown with 30 seeds. For summary purposes, the means, variances, and genotypic correlations from the four matings with the same recurrent parent were pooled within each level of backcrossing. Regression analyses were used to describe the rates of change for genotypic variances and correlations as number of backcrosses increased. In all matings, the trait means regressed toward the recurrent parents as backcrossing progressed. Harvest index was controlled by additive gene action; earliness was partially dominant and tallness was completely dominant; heterobeltiosis occurred for high vegetative growth rate; straw yield and biomass showed either heterobeltiosis or complete dominance; and high grain yield was partially dominant. Unit straw weight showed a positive heterobeltiosis. Log genotypic variances decreased significantly over backcrosses for days to heading, straw yield, and harvest index, whereas for plant height and unit straw weight, the reductions were not significant. Regressions of genotypic correlations were significant for only 12 of 56 trait associations, and changes that did occur were of little consequence.Key words: backcross, interspecific mating, oats.
Nonrandom abortion of ascospores containing alternate alleles at the Tox-1 locus of the fungal plant pathogen Cochliobolus heterostrophus
Authors: Taga M. , Bronson C. R. , Yoder O. C.
Published: November 2014

Crosses involving lab strains of C. heterostrophus that were previously selected for improved fertility yielded high frequencies of four-spored asci and only occasional asci with the full set of eight spores. Fertility in crosses between field isolates was low. Most asci contained two haploid spores; no asci had more than four spores. We investigated the distribution of aborted spores with respect to the three defined genetic loci Mat (mating type), Alb-1 (albinism), and Tox-1 (T-toxin production) and determined the frequency of mitotic twins in four-spored asci. Nonrandom spore abortion was evident from the observations that 80–100% of four-spored asci contained two sets of twins (9% expected for random abortion of mitotic products) and up to 95% of four-spored asci segregated 2:2 for alleles at the Tox-1 locus (67% expected for random abortion of meiotic products), suggesting preferential recovery of nonsister meiotic products. Segregation in crosses between field isolates tended to be skewed in favor of the tox-1a allele (specifies no toxin production). Alleles at Mat and Alb-1 segregated as expected for random abortion of meiotic products in both types of crosses. Low fertility and aberrant segregation among progeny segregating for ability to produce T toxin are likely due in part to abortion-inducing factors linked to Tox-1.Key words: fertility, ascomycetes, T toxin, Helminthosporium maydis, Bipolaris maydis.
Male sterility in Indian mustard (Brassica juncea (L.) Coss). IV. Genetics of MS-4
Authors: Banga Surinder S. , Labana K. S.
Published: November 2014

Male sterile plants of Indian mustard (Brassica juncea (L.) Coss.) were observed in the F2 generation of the cross RLM-198 × EJ-33. The genetic analysis revealed that male sterility occurred when the cytoplasm of RLM-198 interacted with recessive nuclear genes of EJ-33. The genetic constitution of RLM-198 was postulated to be (S) RF RF, EJ-33 as (F) rf rf, and the male sterile plants as (S) rf rf. Varieties of Indian mustard from India mostly contained dominant fertility restorer genes, while European varieties had a greater frequency of the recessive maintainer genes. None of these varieties, however, was capable of complete maintenance of male sterility. Heterosis for yield up to 56% over the national check was observed in field trials. The use of this cytoplasmic male sterile plant in hybrid mustard production will not be economical, until a complete maintainer for male sterility is identified.Key words: Brassica juncea, Indian mustard, male sterility, hybrids.
Cytogenetic studies in spontaneous abortion: the Calgary experience
Authors: Lin C. C. , Braekeleer M. De , Jamro Heidi
Published: November 2014

In a series of 493 apparently consecutive products of spontaneous abortions obtained for cytogenetic studies, tissue culture was attempted in 428 cases; chromosome analysis using the Q-banding technique was completed in 215 cases (50.2%). Abnormal karyotypes were identified in 80 cases (37.2%). Maternal tissue contamination was apparent and the actual frequency of karyotypic abnormal abortuses could be as high as 50%. Comparison of the frequency of a specific type of chromosome abnormalities with nine other series of studies showed the lowest frequency of autosomal trisomies and the highest frequency of triploidies and structural aberrations in the Calgary series. In addition, a significantly lower gestational age was observed for triploidies 69,XXX as compared to the 69,XXY.Key words: abortion, Q-banding, human karyotypes, trisomy, triploidy.
Vernalization and photoperiodic responses of selected chromosome substitution lines derived from 'Rescue', 'Cadet', and 'Cypress' wheats
Authors: Roberts D. W. A. , Larson R. I.
Published: November 2014

The vernalization responses of 'Rescue', 'Cadet', 'Cypress', and selected chromosome substitution lines derived from these cultivars were measured by comparing days to ear emergence of vernalized and unvernalized plants under 24- and 16-h photoperiods. The genotype of 'Cadet' appears to be Vrn1Vrni1, vrn4vrn4, vrnxvrnx (where vrnx is an unidentified locus), and of 'Rescue' vrn1vrn1, Vrn3Vrn3, Vrn4Vrn4. 'Cypress' appears to carry Vrn4 and one or both of vrn1, and vrn3. Although some minor photoperiod responses were observed, no loci involved in major photoperiod responses were detected on chromosomes 5A, 4B, and 5B in 'Rescue' or 'Cadet' or on chromosome 5B in 'Cypress'. However, the duration of the basic vegetative phase appears to be controlled by a locus or loci on chromosome 5B, and chromosomes 5A and 4B may be involved in minor photoperiodic responses.Key words: Triticum aestivum, vernalization, photoperiod responses.
Morphological discrimination among some aneuploids in soybean (Glycine max (L.) Merr.). I. Trisomies
Authors: Gwyn J. Jefferson , Palmer R. G. , Sadanaga K.
Published: November 2014

A study of the phenotypes of four primary trisomies (2n + 1) in soybean (Glycine max (L.) Merr.) was conducted. The purpose was to determine whether measurable and consistent phenotypic differences exist between these trisomics and their disomic sibs. These trisomics are designated Tri A, B, C, and D. These trisomic stocks are homozygous but are not isolines. Root-tip squashes of seedlings were used to identify all trisomic and disomic plants. Several plants of each different trisomic type along with an equal number of their disomic sibs were transplanted to the field and randomized within four separate rows. Nineteen different phenotypic traits were measured on all plants.Stepwise discriminant analysis was used to select variables that were good discriminators (0.10 significance level). Each of the four trisomic–disomic comparisons contained a different but overlapping subset of variables that were used in subsequent discriminant analysis. The first discriminatory variable was computed for each trisomic and disomic plant and plotted on a frequency bar chart. Visual interpretation of the chart, along with an F-test, indicates that these trisomics of soybean cannot be reliably distinguished from their disomic sibs on the basis of the phenotypic traits used in this study.Key words: soybean, trisomic, morphology.
Chromosomal polymorphism for a heterochromatic supernumerary segment in a natural population of Tulipa australis Link (Liliaceae)
Authors: Rejón C. Ruiz , Rejón M. Ruiz
Published: November 2014

Five hundred bulbs of Tulipa australis Link, and where possible the associated young flowers, have been analysed cytogenetically in four natural populations collected from the Sierra Nevada of Spain. A majority of these were diploid (2n = 24), but a few triploids (3n = 36) were present in the population from the highest altitude. All the diploid plants from three of these populations were basic homozygotes with homomorphic bivalents. In one population, however, three types of plants were identified: homozygous standard plants (80%), plants heterozygous for a large supernumerary chromosome segment (19%), and plants homozygous for its same segment (1%). The segment was located terminally on the short arm of a submetacentric chromosome. It was heteropycnotic at meiotic prophase, showed dark C-banding at metaphase I, and was visible as a prominent heterochromatic chromocentre at interphase. The segment divided reductionally in a majority of anaphase I cells (88%), which means that chiasmata tend to be excluded from the arm carrying the segment. Seeds obtained from plants homozygous for the extra segment always carried one such a segment. One-half of the seedlings of heterozygous plants are themselves heterozygotes for the extra segment, while the other half lack the segment. Finally, 11% of the seeds from bulbs without a segment turned out to be segment heterozygotes. From these results, it is deduced that the extra segment is sexually transmitted in a Mendelian fashion and that it has little or no effect on male fertility and fecundity.Key words: polymorphism, chromosomal supernumerary segment, Tulipa australis.
Specific chromosome breakage at meiosis in C-heterochromatin mutants of the grasshopper Euchorthippus pulvinatus
Authors: Santos J. L. , Henriques-Gil N. , Arana P.
Published: November 2014

Three males of Euchorthippus pulvinatus gallicus (Acrididae, Orthoptera) were found to be heterozygous for an enlarged interstitial C-block on the megameric chromosome, which usually has only small C-bands. These individuals exhibited a syndrome of chromosome breakages during the first meiotic division, the presence of the mutant C-bands being associated with the formation of specific weak points, as well as to an increase in sister chromatid cohesiveness. The pattern of breakage observed depends on the location of chiasmata relative to that of weak points and the enlarged C-block.Key words: C-heterochromatin mutant, chromosome breakage, weak point, sister chromatid cohesiveness.
Diploid-like meiotic behavior in synthesized amphiploids of the genus Glycine Willd. subgenus Glycine
Authors: Singh R. J. , Hymowitz T.
Published: November 2014

Six amphiploids consisting of one allotetraploid (2n = 4x = 80), four allohexaploids (2n = 6x = 120), and one allooctoploid (2n = 8x = 160) were synthesized by doubling the chromosomes of F1 interspecific hybrids of the following parents: one diploid (Glycine latifolia 2n = 2x = 40 × G. clandestina, short pod (Sp), 2n = 2x = 40); four triploids (G. clandestina, Sp, 2n = 2x = 40 × G. tabacina 2n = 4x = 80), (G. tabacina 2n = 4x = 80 × G. canescens 2n = 2x = 40), (G. tomentella2n = 4x = 80 × G. canescens 2n = 2x = 40 and its reciprocal); and one tetraploid (G. tomentella2n = 4x = 80 × G. tabacina 2n = 4x = 80). Chromosomal chimerism was observed in the C1 generation. Pod set was recorded in all the colchicine-treated hybrids except in the tetraploid hybrid of G. tomentella × G. tabacina. In C2 generation plants, chromosomal instability was noticed only in the allohexaploid of G. tabacina × G. canescens. All of the amphiploids showed diploid-like meiosis in the majority of the sporocytes and did not exhibit expected multivalent associations, a classical example of allopolyploidy. This was attributed to strong preferential pairing between homologous chromosomes which may be under genetic control.Key words: Glycine, synapsis, interspecific hybrids.
Chromosomal pairing at meiosis of F1 hybrid and backcross derivatives of Triticum aestivum × hexaploid Agropyron junceum
Authors: Charpentier A. , Feldman M. , Cauderon Y.
Published: November 2014

The degree and pattern of chromosomal pairing at first meiotic metaphase were analyzed in several lines of hexaploid Agropyron junceum (2n = 42; genome J1J1J2J2EE), in the F1 hybrid between this species and common wheat, and in the backcrossed progeny of the hybrid to common wheat. Hexaploid A. junceum exhibited a strict bivalent pairing despite the relatedness of its genomes. Chromosomes of the J1 and J2 genomes of Agropyron paired in the F1 hybrid and in the backcross derivatives, in the presence of the Ph1 gene of common wheat. It was concluded that the corresponding chromosomes of the J1 and J2 genomes are distant homologues. It is assumed that the strict bivalent pairing in A. junceum is brought about by a gene system, similar to that found in several autotetraploid species.Key words: Agropyron junceum, Triticum aestivum, common wheat, wheat × Agropyron hybrids, chromosome pairing, bivalentization.
Cytogenetic analysis of some Brazilian marsupials (Didelphidae: Marsupialia)
Authors: Casartelli C. , Rogatto S. R. , Ferrari I.
Published: November 2014

Three species of marsupials from the Amazon region (Marmosa cinerea, Caluromys lanatus, and Didelphis marsupialis) and two from the region of São Paulo (Didelphis marsupialis and Didelphis albiventris) were studied. The G-banding pattern of the species with 2n = 14 (M. cinerea and C. lanatus) was very similar, as well as the pattern of G-bands in the species with 22 chromosomes (Didelphis). All of the autosomes of M. cinerea and D. albiventris have centromeric C-bands and the Y chromosome is totally C-band positive. The long arm of the M. cinerea X chromosome is completely C-band positive except for a negative band close to the centromeric region. In D. albiventris the long arm of the X chromosome is C-band positive except for a negative band close to the telomeric region. In M. cinerea the silver-stained nucleolar organizer regions (Ag-NORs) are found in the acrocentric chromosomes, being located in the telomeric region of one pair and in the centromeric region of the other pair. Caluromys lanatus has centromeric Ag-NORs in one acrocentric and in one submetacentric chromosome pairs. Didelphis marsupialis has three chromosome pairs with telomeric Ag-NORs. In D. albiventris the Ag-NORs are terminal and located in both arms of one pair and in the long arm of two pairs of chromosomes.Key words: cytogenetics, marsupials, chromosomes.
Chromosomal locations of the structural genes for secalins in wild perennial rye (Secale montanum Guss.) and cultivated rye (S. cereale L.) determined by two-dimensional electrophoresis
Authors: Shewry P. R. , Parmar S. , Fulrath N. , Kasarda D. D. , Miller T. E.
Published: November 2014

The chromosomal locations of the structural genes for secalin storage proteins in Secale cereale and S. montanum were determined by electrophoresis of grain proteins from wheat–rye addition and substitution lines. The use of several different extraction procedures and high-resolution electrophoretic systems (one and two dimensional) enabled us to demonstrate that the genes for all the high molecular weight secalins are present on chromosome IRL, and for all the ω-secalins and at least some of the γ-secalins with a relative molecular mass (Mr) of 40 000 on chromosome IRS of both species. In contrast, the genes for the γ-secalins (Mr = 75 000) are located on 2RcS in S. cereale but 6Rm in S. montanum. These observations are discussed in relation to evolution of prolamins and their genes in Secale and related members of the Triticeae.Key words: Secale, rye, seed proteins, structural genes, two-dimensional electrophoresis.
Relationships between inbreeding, meiotic irregularity, and fertility in alfalfa
Authors: Smith S. E. , Murphy R. P.
Published: November 2014

Fertility (seed production) in alfalfa (Medicago sativa L.) is severely depressed by inbreeding; however, little is known of the factors directly responsible for this depression. Irregularities in meiotic behavior could be partially responsible for the inbreeding depression in fertility observed. This study considered relationships between fertility, inbreeding, and irregularity in microsporogenesis. Fertility declined markedly with inbreeding in the materials examined (S0–S3). Irregularity in microsporogenesis, as measured by the percent irregular quartets, (i.e., quartets with micronuclei, supernumerary microspores, or irregular cytokinesis) increased significantly with inbreeding. Increases in quartet irregularity were associated with increases in the number of univalents per pollen mother cell observed at metaphase I. Considering all materials studied, the percentage of irregular quartets was negatively and significantly correlated with fertility as both a seed and a pollen parent. In more detailed analyses, it was observed that the percent irregular quartets was negatively associated with fertility as a pollen parent only when levels of irregularity were relatively high. No association was observed between the percent irregular quartets and fertility when levels of irregularity were relatively low.Key words: Medicago, microsporogenesis, seed production, breeding, fertility.
Complex sex-linked translocation heterozygosity and its role in the evolution of social behaviour
Authors: Rowell David M.
Published: November 2014

Key words: sociobiology, termites, translocation (sex-linked).
Quantitative analysis of the formation of nucleoli in Locusta migratoria
Authors: Diez M. , Puertas M. J.
Published: November 2014

At meiosis of Locusta migratoria, zero, one, or two nucleoli per long (L), medium (M), or short (S) nucleolar organizer region (NOR) bivalent can be clearly seen using an Ag-NOR technique. Diplotene cells with zero to six nucleoli were observed, whose distribution fitted a normal one. However, the distribution of nucleoli in the particular bivalents was not at random. A mathematical model was developed in an attempt to explain this differential activation of nucleoli. The model is based on the assumption that the activation of nucleoli is sequential following successive rounds, in such a way that the probability of a particular L, M, or S nucleolus being activated depends on the type of nucleoli previously activated. The nucleoli activated per cell tend to be distributed among bivalents, and the activation of a second nucleolus in a bivalent has a lower probability than the first one of any bivalent, generating interference. The model was developed for wild-type individuals and it was also applied to mutants that showed a distribution of nucleoli different from wild types, i.e., individuals carrying a translocation between two NOR chromosomes and asynaptic mutants. In both cases the model fits with the observed results. This suggests its general validity.Key words: nucleolus, Locusta, translocation, asynapsis.
Chromosome pairing in Oryza sativa L. × O. latifolia Desv. hybrids
Authors: Nowick E. M.
Published: November 2014

Meiotic chromosome pairing was examined in F1 hybrid regenerants from Oryza sativa (AA) × O. latifolia (CCDD) and O. glumaepatula (AcuAcu) × O. latifolia (CCDD) crosses produced through embryo culture. The average number of chromosome pairs in the O. sativa × O. latifolia regenerants ranged from 13.79 to 14.79. Ten to 18 bivalents were observed per cell. The average number of bivalents in the O. glumaepatula × O. latifolia regenerants ranged from 12.44 to 13.87, with 10–17 bivalents per cell. Some desynapsis occurred but 10 to 12 true bivalents remained at late metaphase in most cells. The high number of bivalents observed in the hybrids from these divergent parents indicates that a genetic system for pairing control similar to that in Triticum may be present in the Oryza genus.Key words: Oryza, embryo culture, meiosis.
Naturally occurring activity variation of an alkaline phosphatase isozyme associated with physiological fitness in an intertidal population of Macoma balthica
Authors: Singh Shiva M. , Green Roger H.
Published: November 2014

We observed variability in the level of an isozyme for the enzyme alkaline phosphatase (AKP, EC 3.1.3.1) in a Macoma balthica population from Hudson Bay. The distribution of "high" and "no" activity AKP-2 variants were different in samples from "high" tide as compared with "low" tide areas. Furthermore, the AKP-2 activity level is associated with survival at high temperature (32 °C), but in the "high" tide subpopulation only. Although this striking association between the activity level of an isozyme and an environmental parameter in a natural population is one of the very few in the literature, further studies are required to establish the genetic basis for the level of the enzyme activity and the biochemical basis for this relationship.Key words: isozyme, alkaline phosphatase, natural selection, evolution.
Genetics of Glossina morsitans morsitans (Diptera: Glossinidae). XI. Identification of the temperature-sensitive period of the mutant allele sabr in females
Authors: Cheeseman M. T. , Gooding R. H.
Published: November 2014

Adult females of the sabr line of Glossina morsitans morsitans Westwood emerging from puparia exposed to 32 or 36 °C during a 24-h period beginning on day 7 of puparial life tended to have longer scutellar apical bristles than did females that emerged from puparia maintained at 23 °C.Key words: Glossina, mutation (sabr), temperature sensitivity.
A comparison of individual, family, and index selection methods in Tribolium castaneum
Authors: McLeod D. L. , Friars G. W.
Published: November 2014

Seven replicates of single-generation selection were used to compare genetic gain in Tribolium castaneum, using methods based on information from individuals, full-sib families, or both. Realized responses in pupa weight were greater when selection was applied in the downward as opposed to the upward direction. Although the contrasts were not all significant, the observed response in the upward direction agreed with theoretical expectations where the ranking of methods was combined first, family second, and individual last. In the downward direction, response based on the family method was below expectations, and the combined method yielded results close to those for selection based on individuals.Key words: selection methods, Tribolium, asymmetric response.
Wheat × maize hybridization
Authors: Laurie D. A. , Bennett M. D.
Published: November 2014

Cytogenetic evidence is presented that the cross between hexaploid bread wheat (Triticum aestivum, 2n = 42) and maize (Zea mays, 2n = 20) results in a hybrid zygote with one complete haploid chromosome set from each parent. Maize chromosomes are subsequently eliminated. This sytem has potential for wheat haploid production and may also allow segments of maize DNA, including transposable elements, to be transferred to wheat.Key words: wide crosses, wheat, maize, chromosome elimination, haploids.
Mode of bivalent formation in desynaptic mutants of chili pepper (Capsicum annuum L.)
Authors: Kumar O. Aniel , Panda Ramesh C. , Rao K. G. Raja
Published: November 2014

Frequencies of pollen mother cells with different numbers of bivalents significantly deviated from that expected with a binomial distribution in Capsicum annuum desynaptic mutants controlled by a recessive gene. This pattern varied in F2 segregants.Key words: Capsicum, chili pepper, desynaptics, bivalent distribution.
Realized genetic parameters from an antagonistic selection index in Tribolium castaneum
Authors: Campo J. L. , Raya L. G.
Published: November 2014

Simultaneous selection of two highly correlated traits was practiced in Tribolium castaneum in a replicated experiment for six generations. Two lines were selected in each of three replicates: P+A− for an antagonistic selection index to increase pupal weight at 21 days and decrease adult weight at 31 days, and P−A+ for an antagonistic selection index to decrease pupal weight and increase adult weight. Genetic correlation between pupal and adult weights estimated in the base population was 0.95. Estimates of realized heritabilities and genetic correlation were obtained and compared with full-sib estimates. For the aggregate genotype, the P+A− line had a significant positive selection response, while the P−A+ line showed a significant negative response as would be expected. The response to divergent selection was asymmetrical, being less for the low pupal weight and high adult weight line than vice versa. Less asymmetry was found for the realized heritability, which agreed very well with the index heritability estimated in the base population. Both individual traits changed in the same direction, increasing for the P+A− line and decreasing for P−A+ line, even though a significant response was found only for pupal weight in the P+A− line. Therefore, the response to antagonistic selection for each individual trait seems to be heavily controlled by the strength of the genetic correlation between them. The realized genetic correlation between pupal weight and adult weight obtained from antagonistic selection index was in excellent agreement with full-sib estimates. Realized heritabilities for each trait were overestimated, especially for adult weight, even though there were essentially no differences between realized and estimated values.Key words: selection (artificial), antagonistic index, parameters (realized), Tribolium.
Intergeneric hybrids between Secale cereale (2x) and Thinopyrum intermedium (6x)
Authors: Fedak George , Armstrong K. C.
Published: November 2014

Hybrids were obtained at the rate of 0.8% of pollinated florets in crossing of Thinopyrum intermedium spp. trichophorum onto Secale cereale cv. Puma. The morphology of the hybrid was similar to the paternal parent. The mean chromosome pairing in the hybrid was 18.80 I + 3.71 II + 0.56 III. A bivalent frequency of 0.04 was attributed to intergenomic pairing, the remainder being autosyndetic.Key words: hybrids (intergeneric), Secale, Thinopyrum, chromosome pairing, autosyndetic pairing.
Pairing competition between identical and homologous chromosomes in diploid and tetraploid cells of rye telotrisomic plants
Authors: Benavente E. , Orellana J.
Published: November 2014

Pairing competition between identical and homologous chromosomes 1R has been directly analyzed in diploid–tetraploid chimeras of telotrisomic plants of rye Secale cereale by using C-bands as cytological markers. The results have shown pairing preferences either in diploid cells, with three doses of 1RS, and in tetraploid cells, with six doses. In both cases, the preferences found could be explained by differential pairing affinities between chromosomes.Key words: telotrisomic, rye, chimeras, banding (C), pairing.
Genetic variation in carotenoid pigment deposition in the red-fleshed and white-fleshed chinook salmon (Oncorhynchus tshawytscha) of Quesnel River, British Columbia
Authors: Withler R. E.
Published: November 2014

Inheritance of the ability to deposit coloured dietary carotenoid pigments in muscle tissue was examined in 16 seapen-reared families of chinook salmon (Oncorhynchus tshawytscha) from the Quesnel River, British Columbia. The progeny red:white ratio varied significantly among families in two sample periods but not between sample periods for individual families. There was no difference between the sexes in proportions of red and white individuals. Total carotenoid extraction of muscle tissue samples from 152 progeny revealed that white individuals contained less carotenoid per gram of tissue (0.24 ± 0.04 μg) than did red ones (3.37 ± 0.14 μg). Estimates of the heritability of flesh colour, when treated as a threshold trait, were 0.93 (sire component) and 0.71 (dam component). A genetic model that invokes two genetic loci, each with two alleles, was proposed to explain the inheritance of flesh colour in Quesnel River chinook salmon. At each locus, one copy of a "red-determining" allele is required for coloured carotenoid pigments to be deposited in muscle tissue. The anomalous red:white ratios among the progeny of one male parent could not be accounted for by tetrasomy or pseudolinkage in conjunction with the proposed model.Key words: Oncorhynchus, salmon, carotenoids, heritability.
Partial amphiploids from wheat (Triticum aestivum) × rye (Secale cereale) crosses
Authors: Gupta P. K. , Fedak George
Published: November 2014

Two groups of three-way hybrids were produced by crossing F1 hybrids of 'Petkus' × 'Prolific' rye (2n = 14) and 'Prolific' × 'Puma' rye (2n = 14) onto 'Chinese Spring' wheat (2n = 42). Meiosis was studied in 89 plants from 29 families from the first combination and in 36 plants from 11 families in the second cross. In three families from the first combination ('Petkus' × 'Prolific') five partial amphiploids with chromosome numbers of 2n = 35, 36, 36, 38, and 41 were identified. The mean bivalent frequencies in five hybrids were 6.71, 7.73, 8.10, 9.94, and 13.00, suggesting that the number of bivalents was generally equal to the number of chromosomes in excess of the expected chromosome number of 2n = 28. These five plants were partial or incomplete amphiploids and their origin was attributed to duplication of a portion of the wheat complement after fertilization.Key words: partial amphiploids, hybrids (intergeneric), Triticum, Secale, chromosome pairing.
Characterization of human chromosomal constitutive heterochromatin
Authors: Babu Arvind , Verma Ram S.
Published: November 2014

The constitutive heterochromatin of human chromosomes is evaluated by various selective staining techniques, i.e., CBG, G-11, distamycin A plus 4,6-diamidino-2-phenylindole-2-HCl (DA/DAPI), the fluorochrome D287/170, and Giemsa staining following the treatments with restriction endonucleases AluI and HaeIII. It is suggested that the constitutive heterochromatin could be arbitrarily divided into at least seven types depending on the staining profiles expressed by different regions of C-bands. The pericentromeric C-bands of chromosomes 1, 5, 7, 9, 13–18, and 20–22 consist of more than one type of chromatin, of which chromosome 1 presents the highest degree of heterogeneity. Chromosomes 3 and 4 show relatively less consistent heterogeneous fractions in their C-bands. The C-bands of chromosomes 10, 19, and the Y do not have much heterogeneity but have characteristic patterns with other methods using restriction endonucleases. Chromosomes 2, 6, 8, 11, 12, and X have homogeneous bands stained by the CBG technique only. Among the chromosomes with smaller pericentric C-bands, chromosome 18 shows frequent heteromorphic variants for the size and position (inversions) of the AluI resistant fraction of C-band. The analysis of various types of heterochromatin with respect to specific satellite and nonsatellite DNA sequences suggest that the staining profiles are probably related to sequence diversity.Key words: polymorphism, heteromorphism, heterogeneity, banding, restriction endonucleases.
Chromosome segregation from cell hybrids.II. Do differences in parental cell growth rates and phase times determine direction of loss?
Authors: Marshall Graves Jennifer A. , Wrigley Jaclyn M.
Published: November 2014

The hypothesis that the direction of chromosome segregation in cell hybrids is determined by the interaction of parent cell cycles, or S-phase times, predicts that the segregant parent will always be the one with the longer cycle, or the longer S phase, and that late replicating chromosomes will be more frequently lost. We have tested this hypothesis by studying cell cycle parameters of mouse, Chinese hamster, and platypus parent cells and by observing chromosome loss and replication patterns in hybrids between them. Two types of hybrids have been studied: mouse–hamster hybrids showed gradual segregation, in one or other direction, of 10–60% chromosomes, while rodent–platypus hybrids (which could be selected under conditions optimal for either parent cell) showed rapid and extreme segregation of platypus chromosomes. We found no correlation between the direction of segregation and the relative lengths of parental cycle times, or phase times, nor between sequence of replication and frequency with which segregant chromosomes are lost. We therefore conclude that the direction and extent of segregation is not directly determined by the interaction of parental cycle or phase times.Key words: cell hybrids, chromosome loss, cell cycle, S phase.