bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for genetic suppression of heterogenetic chromosome pairing in polyploidy species of Solanum, sect. Petota
Authors: Dvořák Jan
Published: November 2014

Data on chromosome pairing in haploids and interspecific hybrids of Solanum, sect. Petota reported in the literature were used to determine whether the diploidlike chromosome pairing that occurs in some of the polyploid species of the section is regulated by the genotype or brought about by some other mechanism. The following trends emerged from these data. Most of the polyploid × polyploid hybrids had high numbers of univalents, which seemed to indicate that the polyploid species were constructed from diverse genomes. Haploids, except for those derived from S. tuberosum, had incomplete chromosome pairing. All hybrids from diploid × diploid crosses had more or less regular chromosome pairing, which suggested that all investigated diploid species have the same genome. Likewise, hybrids from polyploid × diploid crosses had high levels of chromosome pairing. These paradoxical results are best explained if it is assumed that (i) the genotypes of most polyploid species, but not those of the diploid species, suppress heterogenetic pairing, (ii) that nonstructural chromosome differentiation is present among the genomes of both diploid and polyploid species, and (iii) the presence of the genome of a diploid species in a polyploid × diploid hybrid results in promotion of heterogenetic pairing. It is, therefore, concluded that heterogenetic pairing in most of the polyploid species is genetically suppressed.
Assignment of 6-phosphogluconate dehydrogenase and glucose oxidase to chromosome 2 of Anopheles albimanus
Authors: Narang S. , Seawright J. A. , Mukiama T. K. , Willis N. L.
Published: November 2014

As a part of a comprehensive, continuous effort to define a linkage map for Anopheles albimanus Wiedemann, 6-phosphogluconate dehydrogenase (6-Pgd) and glucose oxidase (Go) were assigned to the right arm of chromosome 2. Male-linked translocations and mutant markers were used to establish the map distance and the current sequence of loci on chromosome 2 as follows: brown larva (bw) – ? – ebony (eb) – ? – centromere – ? – T(Y;2R)3 – 17 – Go – 6(?) – bald palpi (bp) – 10 – green larva (gl) – 7 – propoxur resistance (prr) – 2 – red eye (re) – 21 – 6-Pgd.
The D genome of the Triticeae
Authors: Kimber G. , Zhao Y. H.
Published: November 2014

Twenty interspecific hybrid combinations involving wheat D-genome species were made and their first meiotic metaphase chromosome pairing was observed. Optimum values of the relative affinity of the most closely related genomes were calculated. It is possible to divide the species into three clusters: first, Triticum tauschii, T. aestivum, T. cylindricum, and T. ventricosum, in which the D genome has undergone little modification; second, tetraploid and hexaploid T. crassum in which the D genome is somewhat modified; and third, T. juvenale and T. syriacum, in which the D genome is substantially modified.
Evidence on the origin of the G genome in wheat: cytology and fertility of a T. timopheevi-like mutant
Authors: Kushnir U. , Halloran G. M.
Published: November 2014

A spontaneous somatic mutant with Triticum timopheevi Zhuk. plant morphology was found in late tillers of a Triticum turgidum L. var. dicoccoides (Bowden) plant. Hybrids of the timopheevi-like mutant with T. turgidum L. var. dicocooides (Bowden), T. timopheevi Zhuk., and T. araraticum Jakubz. exhibited irregular pairing at meiosis and sterility, almost normal pairing and fertility, and relatively high pairing and sterility, respectively. This evidence plus that of karyotype changes in the somatic mutant indicated that it was differentiated from T. turgidum dicoccoides through chromosome interchanges. This mutation, believed to arise through chromosome rearrangement, is discussed in relation to the origin of the G genome of T. timopheevi.
SD-72 has a temperature-sensitive period during spermiogenesis
Authors: Matthews Kathleen , Mortin Mark A.
Published: November 2014

Segregation distorter (SD) chromosomes in Drosophila melanogaster are naturally occurring second chromosomes which produce greatly altered transmission frequencies when present in heterozygous males (Hartl and Hiraizumi 1976). The proximate cause of segregation distortion is abortion of spermatids carrying the non-SD homologue (Tokuyasu et al. 1977). SD-72, a chromosome previously shown (Mange 1968) to be unaffected by high temperature treatment of spermatocytes, a stage when several SD genotypes are temperature sensitive, has a temperature-sensitive period during spermiogenesis. SD-72/cn bw males exposed to a 24-h pulse of 29 °C, then brooded for 24 h, experience a decrease in segregation distortion of approximately two-thirds. The timing of the reduction in distortion indicates that the temperature-sensitive period is postmeiotic.
Association of telocentric bivalents representing the two different arms of one chromosome in rye
Authors: Yacobi Y. Z. , Levanony H. , Feldman M.
Published: November 2014

Telocentric bivalents representing the two different arms of one chromosome tend to lie close to one another at first meiotic metaphase of rye, Secale cereale L. This association provides evidence that ordered arrangement of chromosomes, previously found in rye somatic cells, is also maintained on the metaphase plate of meiotic cells.
Duration of meiosis and spermiogenesis in the dog
Authors: Ghosal S. K. , LaMarche P. H. , Bhanja P. , Joardar S. , Sengupta A. , Midya T.
Published: November 2014

The duration of meiosis and spermiogenesis was studied in the dog by following the kinetics of [3H]thymidine-labeled canine spermatocytes autoradiographically. Leptotene appears to last for at least 4.20 days, zygotene for less than a day, and pachytene for about 15.50 days. The transition from diplotene to metaphase II is extremely rapid and requires approximately a day. The duration of spermiogenesis is at least 19.60 days. Both meiosis and spermiogenesis are completed by 42.15 days.
Triplo-X hermaphrodite of Caenorhabditis elegans: pachytene karyotype analysis, synaptonemal complexes, and pairing mechanisms
Authors: Goldstein Paul
Published: November 2014

Pairing of the three X chromosomes in the triplo-X strain of Caenorhabditis elegans occurs at pachytene in a two-by-two fashion such that one bivalent and one univalent are formed. The XX bivalent pairs synchronously with the autosomes and the univalent X remains in a similar chromatic state as the rest of the chromosomal complement. Normal tripartite synaptonemal complexes (SC) are formed between all bivalents. The univalent X lacks a SC and an axial core is not observed. The condensation of the univalent X in the triplo-X is different than in the male where the univalent X is heterochromatic. This real difference in condensation states of the chromatin may explain the fact that the univalent X is maintained in the male line yet it is easily lost in the triplo-X strain.
The effect of telomeric heterochromatin on the frequency of aneuploids in triticale (× Triticosecale)
Authors: Dillé J. E. , Gustafson J. P. , Bennett M. D.
Published: November 2014

The relationship between the frequency of aneuploids and blocks of telomeric heterochromatin on rye (Secale cereale L.) chromosomes in a triticale (× Triticosecale Wittmack) background was investigated. Lines with or without blocks of telomeric heterochromatin were examined to determine the percentage of aneuploid progeny. The results showed that the amount of telomeric heterochromatin present on rye chromosomes 4R and 6R had little effect (2%) on lowering the proportion of aneuploids. When rye chromosome pair 2R was replaced by wheat chromosome 2D in the presence of chromosomes 4R and 6R lacking heterochromatin, the percentage of aneuploids increased slightly (2.7%) over that found in the control population.
The karyotype of the skink, Mabuya blandingi
Authors: Adegoke J. A.
Published: November 2014

The chromosomes of Mabuya blandingi were studied from the bone marrow of male and female animals. The diploid chromosome number in this organism is 32, consisting of 10 large-, 10 medium-, and 12 small-size chromosomes. The fundamental number (NF) is 48. The chromosome complements in both the male and female animals are similar in morphology with no evidence of differentiated sex chromosomes.
Phylogenetic relationships between chromosomes of wheat and chromosome 2E of Elytrigia elongata
Authors: Dvořák J. , Chen K. C.
Published: November 2014

Gametophytic compensation of the Elytrigia elongata chromosome 2E for wheat chromosomes was assessed by determining the vigour of the gametophytes having the Elytrigia chromosome substituted for a wheat chromosome relative to normal wheat gametophytes. These tests showed that chromosome 2E compensated in the gametophyte for wheat chromosomes 2B and 2D, but not for 2A. The Elytrigia chromosome was also occasionally transmitted by male gametophytes when substituted for chromosomes 3A, 4B, and 6B. Chromosome 2E was then substituted for chromosomes 2A, 2B, and 2D. In each disomic substitution the Elytrigia chromosome showed good compensation for the nullisomy of the respective wheat chromosome, as indicated by normal vigor and fertility of the plants. These data confirmed that E. elongata chromosome 2E is phylogenetically related to wheat chromosomes of homoeologous group 2.Key words: Triticum, Elytrigia, phylogeny, wheat.
Triploidy in the genus Antennaria (Asteraceae: Inuleae)
Authors: Chinnappa C. C.
Published: November 2014

Chromosome numbers for individuals from 87 populations of Antennaria from western Canada were counted. Naturally occurring triploid (2n = 42) hybrid populations between diploid (2n = 28) Antennaria microphylla Rydb. and two tetraploid (2n = 56) species Antennaria rosea Greene and Antennaria umbrinella Rydb. are reported for the first time. With the discovery of the triploid populations, an entire euploid series (2x–8x) has been established for the genus Antennaria.Key words: polyploidy, Antennaria, hybridization, agamospermy, taxonomy.
Random single chromatid and nonrandom double chromatid type segregation of human acrocentric chromosomes in BrdU-labeled mitoses
Authors: Chemitiganti S. , Verma R. S. , Brat S. Ved , Dosik H.
Published: November 2014

Chromatid segregation was analyzed using satellite association of 5-bromodeoxyuridine (BrdU) differentially stained acrocentric chromosomes of human leukocytes. Data were classified into cis and trans configurations in second and third division cycles. It was found that single chromatid types have random segregation (1:1) while nonrandom segregation was noted for double chromatid types. The nonrandom segregation hypothesis of earlier investigators needs to be reexamined.Key words: chromatid segregation, BrdU, mitosis, acrocentric.
Meiotic abnormalities of Vaccinium ashei × Vaccinium darrowi hybrids
Authors: Goldy R. G. , Lyrene P. M.
Published: November 2014

Meiosis was studied in pollen mother cells of three Vaccinium ashei (2n = 6x = 72) × Vaccinium darrowi (2n = 2x = 24) hybrids. Numerous irregularities were found, including 60 somatic chromosomes instead of the expected 48, two synezetic knots, two nucleolar organizing regions, lagging chromosomes at anaphase I and II, nonassociating chromosomes, meiotic asynchrony, micronuclei at telophase I and II, misaligned spindles, extra nucleoli, increased percentage of unreduced gametes, incomplete tetrads, and polyspory. Lagging chromosomes at anaphase I did not appear as univalents, but as bivalents. This suggests a base chromosome number for Vaccinium of x = 6, not x = 12.Key words: Vaccinium ashei, rabbiteye blueberry, Vaccinium darrowi, interspecific hybridization, cytogenetics, meiosis.
Distribution of sister chromatid exchanges on the mouse chromosomes in vivo with reference to the replication properties of the X chromosome
Authors: Singh S. M. , Reimer D. L.
Published: November 2014

Frequency of sister chromatid exchanges (SCE) were recorded separately for different chromosomes from bone marrow cells of female mice of the two genetic strains (C3H/S and C57BL/6J). SCEs were evaluated following different doses of 5-bromo-2′deoxyuridine (BrdU) as nine hourly i.p. injections. The SCE per cell increased with increasing BrdU doses which was slightly higher in C3H/S than in the C57BL/6J. SCEs per cell were variable at every treatment – strain combination, possibly reflecting the heterogeneous nature of the bone marrow cells. In general, there is a positive correlation between SCE per chromosome and the relative chromosome length. Total SCEs on one of the large chromosomes (most likely the X chromosome), however, are significantly higher than expected on the basis of relative length alone. Most of this increase is attributable to one of the homologues of this chromosome, which is not in synchrony with the rest of the chromosomes and may represent the late-replicating X. These results when viewed in the light of replication properties of the heterochromatinized X, suggest a direct involvement of DNA replication in SCE formation and may argue against the replication point as the sole site for the SCEs.Key words: sister chromatid exchange, BrdU, recombination, replication, X chromosome.
Color-morph genetics in the terrestrial isopods Armadillidium nasatum and Porcellionides virgatus
Authors: Johnson Clifford
Published: November 2014

This paper reports the inheritance of color morphs in two terrestrial isopods, Armadillidium nasatum and Porcellionides virgatus. Six and three pure breeding color morphs have been developed in the isopods, A. nasatum and P. virgatus, respectively. In the former species, pigmented morphs involve body and eye colors and the albino morph lacks body pigments but possesses normal eyes. The morphs have been explained by way of three loci each with two alleles. The latter species exists in two body pigment morphs and an albino form essentially lacking all pigments. Two loci are involved. The homologous nature of gene loci in terrestrial isopods is reviewed and areas of evolutionary genetics are identified where these markers may be employed.Key words: isopod color morphs, homologous loci.
Aberrant nuclear morphology in the mouse myeloma SP2/0 cell line
Authors: Franklin Angus L. , Irvin Randall T. , Filion W. Gary
Published: November 2014

The mouse myeloma SP2/0 cell line when grown in supplemented Dulbecco's modified Eagle's media spontaneously produced aberrant nucleated cells which increased in frequency with cell culture age. These cells underwent cytological changes associated with apoptosis, that is, the condensation of chromatin followed by karyorrhexis and the production of small apoptotic bodies. Aberrant cells were induced by media changes, centrifugation, and temperature shocking. The rapid induction of aberrant cells by a media change suggests that the mechanism of fragmentation was not associated with cell division.Key words: mouse, myeloma, SP2/0, apoptosis.
Linked digenic epistasis in the inheritance of tillering and yielding ability in a cross of wheat
Authors: Patel J. D. , Bains K. S.
Published: November 2014

The nature of genetic variation in an intervarietal cross ('WG 377' × 'Sonalika') of bread wheat (Triticum aestivum L. em Thell.) was determined for grain yield and tillers per plant by analyzing 21 generation means and 36 family variances. For both traits, duplicate epistasis of linked loci in the pairs and gene dispersion was observed through the analysis of 21 generation means. The analysis of generation variances further suggested repulsion phase linkages for the gene pairs. The additive genetic component was significant for both traits in each of the analyses. Prevalence of gene dispersion suggested the possibility of high transgressive segregation. However, the task of exploiting additive genetic variation would be difficult because of duplicate epistasis and repulsion phase linkages. Considering these results a breeding procedure like biparental mating among a large number of superior F2 plants which encourages crossing-over is suggested.Key words: Triticum, linked epistasis, quantitative traits, additive effects, tillering.
Variabilité enzymatique chez le maïs
Authors: Chevallier Marie-Hélène , Dattee Yvette
Published: November 2014

Isozymes of eight enzymatic systems were determined in 22 maize landraces from Latin America, 27 from Africa, and 1 composite, and were analyzed by multivariate analysis. Efficiency of hybridization in producing the composite was evaluated with enzymatic markers. The composite closely resembled the Mali ecotypes from which 60% of its genetic constitution was derived. Prediction of heterosis in yield as related to enzymatic differences in parents of a hybrid is discussed.Key words: Zea mays L., Latin America, enzyme variability, multivariate analysis, heterosis.
The theory of the pairing of telocentric chromosomes in triploids and trisomics
Authors: Kimber G. , Alonso L. C.
Published: November 2014

The possible pairing patterns of telocentric chromosomes in triploids and trisomics are considered and expressions are derived allowing the prediction of expected meiotic, chromosomal, and cellular pairing patterns. The calculation of the relative affinity of the homoeologous chromosomes involved in the pairing patterns with the telocentrics is discussed.Key words: Triticum, triploid, trisome, synapsis, telocentric.
Studies in Crataegus. X. A note on the occurrence of diplospory in Crataegus dissona Sarg. (Maloideae, Rosaceae)
Authors: Muniyamma M. , Phipps J. B.
Published: November 2014

This paper records the occurrence of diplospory for the first time in the genus Crataegus L. (Rosaceae). It occurs in C. dissona Sarg., a scarce triploid (2n = 51) of the Great Lakes – New England region. Proof of diplospory is derived from the somatic chromosome count, frequency of trivalents in metaphase I. and cytological study of embryo sac development. The majority of apomictic Crataegus studied, however, are aposporous.Key words: diplospory, apomixes, parthenogenesis, Rosaceae.
Genetics of Glossina morsitans morsitans (Diptera: Glossinidae). IX. Definition of linkage group III and further mapping of linkage groups I and II
Authors: Gooding R. H.
Published: November 2014

In Glossina morsitans morsitans Westwood, linkage group III is defined as the autosome carrying the locus Mdh (malic dehydrogenase), the only locus so far identified in this linkage group. The locus αGpd.2 (α-glycerophosphate dehydrogenase) was located 45 map units (MU) to the left of Xo (xanthine oxidase) and the loci Est.1 and Est.2 (loci for two esterases found in the thorax) were mapped approximately 5–10 MU to the right of Ao (aldehyde oxidase) in linkage group II. The location of G6pd (glucose-6-phosphate dehydrogenase) has been confirmed to be approximately 37 MU to the left of oc (ocra body color) in linkage group I and it was shown that this region of the X chromosome does not involve the large paracentric inversion found in the Handeni line. A genetic map for 12 loci in the three linkage groups found in G. m. morsitans is presented.Key words: Diptera, Glossina, mapping, inversion, isozymes.
Genetic control of meiosis in rice, Oryza sativa L. IV. Cytogenetical analyses of asynaptic mutants
Authors: Kitada Kunio , Omura Takeshi
Published: November 2014

One complete asynaptic mutant, MM-19, and two partial ones, MM-4 and MM-16, of Oryza sativa L. induced by N-methyl-N-nitrosourea (MNU) were cytogenetically investigated. No chromosome pairing occurred from zygotene to pachytene and 24 univalents appeared at diakinesis and metaphase 1 in MM-19. On the other hand, a partial lack of chromosome pairing was observed from zygotene to pachytene and various numbers of univalents occurred at metaphase I in MM-4 and MM-16. The mean chiasma frequency per bivalent as well as per cell decreased to different extents in MM-4 and MM-16, and the correlation between both the amount of chromosome pairing from zygotene to pachytene and the chiasma frequency per cell at diakinesis was recognized. Judging from the development of anthers in each meiotic stage, the duration of the stage forming the synizetic knot, at which chromosome pairing took place, was longer in MM-4 and MM-16 than in the normal plant, and was in MM-19 almost as long as in the normal plant. The results of gene analyses indicate that each of the three asynaptic mutants is controlled by a recessive gene and that, at least for MM-4 and MM-16, these genes are located at different loci.Key words: asynaptic, rice, Oryza, chiasma frequency, synizesis.
Highly repeated DNA and holocentric chromosomes of the woodrush Luzula flaccida (Juncaceae)
Authors: Collet Chris
Published: November 2014

Three highly repeated DNA components were characterized from Luzula flaccida. The 1.683 g/cm3 satellite accounts for 22% of the genome and has a sequence complexity of 127 base pairs (BP). A further 8% of the genome consists of a cryptic satellite DNA with a repeating unit of 190 BP. A minor satellite component of buoyant density 1.681 g/cm3 constitutes less than 2% of the total DNA and has a unit length of 184 BP. The presence of segments of the 1.683 satellite DNA lacking Mbol cleavage sites suggests that amplification of sequence variants may have occurred during the evolution of this satellite. While the distribution of satellite DNA appears to be different in being interspersed along the holocentric chromosomes of L. flaccida, the structure and mode of evolution of highly repeated DNA appears to follow the same pattern as seen in organisms with localized centromeres.Key words: Luzula, holocentry, highly repeated DNA.
Relationship of brown adipose tissue with growth and obesity differences in genetically selected mouse lines
Authors: Saxton A. M. , Eisen E. J. , Leatherwood J. M.
Published: November 2014

A recent hypothesis considers brown adipose tissue (BAT) to be an important source of diet-induced thermogenesis (DIT). In turn, DIT and thermogenesis in general are believed to be key factors in the control of obesity of laboratory rodents. This hypothesis was developed from the study of single gene mutant obese rodents. The present research tested this hypothesis in mice with polygenic control of growth and obesity, which is more characteristic of the type of genetic variation expected in human and other mammalian populations. Control and high fat diets were used to test responses of five genetically selected lines of mice showing different patterns of growth and obesity. All lines deposited more fat on the high fat diet, but the most obese line showed the largest increase in BAT and the lipid-free dry (LFD) component of BAT. Use of LFD per unit body weight gave results which supported the hypothesis being tested, but it was argued that this measure is misleading. When brown and white adipose tissue growth relative to body weight were examined, 2 of the 10 line – diet groups showed alterations in BAT growth patterns. However, it was concluded that BAT, if involved at all, was not a major factor in growth and obesity differences.Key words: obesity, polygenes, adipose tissue, quantitative inheritance, mouse.
Cytogenetic studies of alfalfa weevil (Hypera postica) strains (Coleoptera: Curculionidae)
Authors: Hsiao Catherine , Hsiao T. H.
Published: November 2014

Chromosome karyotypes, chiasma frequencies, and Giemsa C-banding patterns were analyzed from eight weevil populations: three of the eastern strain (Beltsville, MD; State College, PA; and Washington Co., IL) and two of the western strain (Logan and St. George, UT) of the alfalfa weevil, two of the Egyptian alfalfa weevil (Yuma, AZ and Westmorland, CA), and one weevil population from Wageningen, Netherlands. All of these weevil populations have the same chromosome number, 2n = 20 + XYp, which is identical to that reported previously for five other Hypera species. The chromosome number for the clover leaf weevil, Hypera punctata (Fabricius), is 2n = 18 + neo-XY which appears to be phylogenetically different from other Hypera species. The lack of cytogenetic variations among the eight weevil populations under investigation leads us to conclude that all weevil strains in the United States are of the alfalfa weevil, H. postica (Gyllenhal), and that the use of H. brunneipennis Boheman for the Egyptian alfalfa weevil of North America should be discontinued.Key words: Hypera postica, cytogenetics, chromosomes, C-banding, alfalfa weevil.
The C-band pattern of a Ph− mutant of durum wheat
Authors: Dvořák J. , Chen Kuey-Chu , Giorgi B.
Published: November 2014

A mutation of the Ph gene which normally suppresses heterogenetic chromosome pairing was obtained in cultivar 'Cappelli' of Triticum turgidum L. em Morris et Sears var. durum. The chromosomes of 'Cappelli,' the Ph− mutant, and another 'Cappelli' line suspected to have a duplication of part of arm 5Bq (5BL) were C-banded. Compared with arm 5Bq of the parental cultivar, the 5Bq arm of the Ph− mutant was shorter owing to a deletion of one of two interband regions in the middle of the arm. In the line suspected to have a duplication, the 5Bq arm was longer than in 'Cappelli' and the interband region that was absent in Ph− was twice as long. An interchange between sister chromatids or homologous chromosomes is suggested to be responsible for the deletion and tandem duplication of the chromosome region. The C-band patterns are used to infer the approximate location of the Ph gene in the 5Bq arm.Key words: wheat, C-band, deletion, duplication, Triticum, 5B chromosome.
Genetic variation for monomer–dimer equilibria of esterase-5 in Drosophila pseudoobscura, Drosophila persimilis, and Drosophila miranda
Authors: Townsend David R. , Singh Rama S.
Published: November 2014

Esterase-5 is a highly polymorphic enzyme in Drosophila pseudoobscura and its close relatives. Numerous alleles have been identified by employing a number of physicochemical properties of the enzyme (e.g. electrophoretic mobility, enzyme stability, subunit dimerization, and variation in monomer–dimer equilibrium). Variation in the monomer–dimer equilibrium of esterase-5 leads to differences in electrophoretic mobility of monomers produced by dimers all of which have the same mobility. In this report we have used this criterion to study variation within, as well as between, four closely related species: D. pseudoobscura pseudoobscura, D. pseudoobscura bogotana. D. persimilis, and D. miranda. All lines were characterized for esterase-5 monomer and dimer mobility at a number of gel concentrations and the comparison was made by plotting log10 monomer – dimer mobility as a function of gel concentration. No variation was found within D. p. pseudoobscura or D. p. bogotana but some variation (two distinct alleles) did occur in D. persimilis. Drosophila miranda is segregating for two alleles, one of which is fixed in D. pseudoobscura and the other one is common in D. persimilis. Thus it seems that the variation in monomer–dimer equilibrium is a rather conservative criterion and that the variation in D. miranda is a good deal older than the speciation event(s) which gave rise to D. miranda and the lineage leading to D. pseudoobscura and D. persimilis.Key words: esterase-5, Drosophila pseudoobscura, monomer–dimer equilibrium, population, polymorphism, speciation, electrophoresis.
The genetic nature of mutations of a gene for yellow pigment linked to Lr19 in 'Agatha' wheat
Authors: Knott D. R.
Published: November 2014

In previous work, two mutations that resulted in lower levels of yellow pigment in flour had been produced in 'Agatha' wheat which carries a wheat–Agropyron translocation. To determine whether the mutations involved the gene for yellow pigment or a suppressor at another locus, the two mutants were crossed with 'Neepawa' and 'Manitou.' Segregation for a suppressor did not occur in the F2 and F3 generations. Thus it appeared that the mutations involved the pigment locus.Key words: Triticum, translocation, yellow pigment, Agropyron.
Segmentation patterns and mechanisms of genome multiplication in cultured microspores of barley
Authors: Chen C. C. , Kasha K. J. , Marsolais A.
Published: November 2014

Microspore segmentation in anthers of the barley line C4-13 cultured on a modified N6 medium was followed for 10 days to examine the routes to multicellular structure formation and origin of nonhaploid chromosome numbers. The first division of the uninucleate microspores gave rise to two similar nuclei or a large vegetative and a small generative cell. The two similar nuclei divided independently and both contributed to the formation of multicellular structures. Independent division of the vegetative and generative cell, and division of the vegetative cell alone resulted in two other pathways to multicellular structure formation. Nuclear fusion and endomitosis occurred in some pathways and appeared to be involved in ploidy variation. In addition, a very low frequency of fusion between the nuclei of two microspores was observed. This event may account for the occasional presence of heterozygosity in microspore-derived plants.Key words: barley (Hordeum vulgare), anther culture, androgenesis, ploidy level, nuclear fusion, endomitosis, gene expression.
The incidence of spontaneous cytogenetic aberrations in lymphocytes cultured from normal humans for 48 and 72 h
Authors: Sinha Anil K. , Linscombe V. Ann , Gollapudi B. Bhaskar , McClintock Mary L. , Flake Raymond E. , Bodner Kenneth M.
Published: November 2014

Spontaneously occurring cytogenetic aberrations were compared in 48- and 72-h human lymphocyte cultures from a group of 20 normal male volunteers. Mitotic indices for both cultures times were also evaluated. BUdR (5-bromo, 2-deoxyuridine) labelled metaphases from three men were utilized to determine the cell cycle kinetics in the medium used. There was no statistically significant difference between 48- and 72-h cultures among the majority of aberration categories considered. Possibly, the lymphocyte populations at the two different culture times maintained a consistent yield level. Mitotic indices in 72-h cultures were invariably higher than those in 48-h cultures. An overwhelming number of first division metaphases were observed at 48 h of incubation; however, approximately 22% of the lymphocytes did not enter into mitosis until 72 h in culture. A number of difficulties with regard to utilizing BUdR-labelled first division metaphases for cytogenetic analyses are discussed.Key words: BUdR, lymphocytes, mitosis, culture.
Inversion polymorphisms in natural populations of Anopheles stephensi
Authors: Mahmood Farida , Sakai R. K.
Published: November 2014

A preliminary survey of natural populations of Anopheles stephensi Liston in Pakistan has uncovered the presence of 16 autosomal paracentric inversions. Twelve previously undescribed inversions were observed in the field populations and an additional new one was seen in a laboratory colony. A comparison of urban and rural populations showed striking differences in the kinds and frequencies of paracentric inversions.Key words: Anopheles stephensi, inversions, chromosomal polymorphisms.
Chromosome segregation from cell hybrids. I. The effect of parent cell ploidy on segregation from mouse – Chinese hamster hybrids
Authors: Marshall Graves Jennifer A.
Published: November 2014

To determine whether the dosage of some parental factor influences the direction and extent of chromosome segregation, I have constructed hybrids between polyploid series of mouse and Chinese hamster lines. The input ratio of mouse: hamster chromosomes varied from 3.3 (in hybrids between diploid hamster and polyploid mouse cells) and 0.9 (in hybrids between polyploid hamster and near-diploid mouse cells). Mouse chromosomes were retained and hamster chromosomes were lost from all hybrids with input ratios ≥ 1.3; the extent of hamster chromosome loss increased from 25 to 60% as the proportion of mouse chromosomes was increased. Reverse segregation was observed in hybrids in which the ratio was 0.9; hybrids between polyploid hamster and diploid mouse cells retained most hamster chromosomes and lost 52% of mouse chromosomes. I conclude that the direction and extent of chromosome segregation from these hybrids depends on the dosage of some factor contained in the parent cells; because the volumes of polyploid cells are proportional to chromosome number, this factor could be chromosomal, nuclear, or cytoplasmic. Dosage differences should therefore be considered when comparing chromosome segregation from hybrids with cells of the same species combination, but which might differ in chromosome number (e.g., diploid lines and established lines), or cell volume (e.g., cells from different tissues).Key words: cell hybrids, mouse – hamster, segregation, chromosome loss, ploidy.
Genomic relationships in the Hordeum brevisubulatum complex
Authors: Landström Tomas , Bothmer Roland von , Dewey Douglas R.
Published: November 2014

Hybridization and cytogenetic studies of the Asiatic species Hordeum brevisubulatum (Trin.) Link s. lat. were carried out. Material from all subspecies were included, viz. ssp. brevisubulatum (2x), ssp. nevskianum (Bowden) Tzvel. (4x), ssp. turkestanicum (Nevski) Tzvel. (4x, 6x), ssp. iranicum Bothmer (6x), and ssp. violaceum (Boiss. &Hohen.) Tzvel. (2x, 4x). Apart from the triploid hybrids, which for cytological reasons were highly sterile, all other combinations had good fertility, indicating a close relationship between the parents. Data from meiotic pairing in the hybrids indicates that the whole complex is of autoploid nature, with one "basic" genome. However, there are several examples of structural rearrangements of chromosomes indicating differentiation of the basic genome, but mainly on the population level.Key words: Hordeum brevisubulatum, intraspecific hybridization, meiosis.
Oncogene-related sequences in xiphophorin fish prone to hereditary melanoma formation
Authors: Vielkind Juergen R. , Dippel Eva
Published: November 2014

In certain xiphophorin fish, a whole spectrum of melanomas of varying severity can be produced on a genetic basis, from benign melanomas composed of almost fully differentiated (mature) pigment cells to malignant melanomas composed of very incompletely differentiated (immature) pigment cells. This feature should provide an excellent basis for the study of the role of oncogenes in this melanoma formation as well as in cell development. This is a preliminary study reporting the screening of the genomes of Xiphophorus helleri (swordtail) and four different strains of X. maculatus (platyfish) for the presence of oncogene sequences using cloned probes of v-src, v-rasKi, c-mys, and c-mos in Southern blot analysis. Under high stringency conditions, a very complex hybridization pattern was observed in the DNA of the fish when probed with v-src and v-rasKi; it was less complex when probed with c-myc. No hybridization pattern was found in any DNA with c-mos, even under low stringency conditions. The complex patterns suggest a relatively high copy number of v-src and v-rasKi related sequences in the genomes of the fish. The patterns obtained for the DNAs of the two species are very similar, if not identical, with two interesting exceptions. Xiphophorus helleri DNA shows a more complex v-src pattern than the DNAs of the X. maculatus strains, perhaps indicating a higher copy number. The DNAs of two X. maculatus strains, one a deletion mutant of the other, show a single v-src related band difference in their patterns.Key words: hereditary melanomas, cell development, oncogenes, xiphophorin, fish.
A new diploid chromosome number for tomato (Lycopersicon esculentum)?
Authors: Banks P.
Published: November 2014

The recognized chromosome number of tomato has been 2n = 24. In this paper the chromosome number 2n = 26 is reported in 18 varieties of tomato. One commercial hybrid variety, revealed 25 mitotic chromosomes. This variety, as well as the varieties with 26 chromosomes, appeared to be fully fertile. Different chromosome numbers did not appear to be associated with any morphological differences between the varieties examined. Preliminary meiotic examination of the variety 'Flora-Dade' (2n = 26 mitotic chromosomes) sometimes revealed 12 associations of chromosomes and sometimes 13 associations. Meiotic examination of the variety 'Sunny' (2n = 25 mitotic chromosomes) revealed what appeared to be 12 bivalents. Centric fission may account for the numerical variation of the diploid chromosome number of tomatoes.Key words: Lycopersicon, tomato, chromosome number, centric fusion.
Intergenomic suppression of endosperm protein genes in common wheat
Authors: Galili G. , Feldman M.
Published: November 2014

Total endosperm proteins from both several hexaploid wheat lines (genome AABBDD) and their extracted tetraploid derivatives (genome AABB) were fractionated on one-dimensional polyacrylamide gel electrophoresis. Several protein bands of the hexaploid lines were absent in the gel patterns of their tetraploid derivatives. These proteins are presumed to be controlled by genes of the D genome. On the other hand, each extracted tetraploid line possessed several bands which were either missing or weakly stained in the gel pattern of its hexaploid progenitor. This suggests that D genome genes may suppress or effect the biosynthesis of these proteins. The suppressive effect of the D genome reappeared in synthetic amphiploids produced from one extracted tetraploid and several lines of Aegilops squarrosa, the donor of the D genome. The possible role of intergenomic gene interactions in regulating the optimal production of endosperm proteins in polyploid wheats is discussed.Key words: gene interaction, genetic diploidization, endosperm proteins, electrophoresis, polyploid wheat, Triticum aestivum.
The heterochromatin distribution and genome evolution in diploid species of Elymus and Agropyron
Authors: Endo T. Ryu , Gill Bikram S.
Published: November 2014

The acetocarmine–Giemsa C-banding technique was used to study heterochromatin distribution in somatic chromosomes of diploid Elymus junceus (= Psathyrostachys juncea) (2n = 14) (genome designation Ju = N) and nine diploid Agropyron species (2n = 14): A. cristatum (C = P), A. imbricatum (C = P), A. elongatum (= Elytrigia elongata = Thinopyrum elongatum) (E = J), A. junceum (= E. bessarabicum = T. bessarabicum) (J = E), A. spicatum (= Pseudoroegneria spicata) (S), A. libanoticum (= P. libanotica) (S), A. ferganense (S), A. stipifolium (= P. stipifolia) (S), and A. velutinum (V). With the exception of A. elongatum and A. velutinum, which were self-fertile, all species were cross-pollinating and self-sterile. The cross-pollinating species showed large terminal C-bands and a high level of C-band polymorphism. Agropyron elongatum, moderately self-fertile, showed small terminal and interstitial bands and a minimal C-band polymorphism. Agropyron velutinum, fully self-fertile, almost totally lacked C-bands. The Ju, C, E, and J genomes appeared to be distinctive and the equivalence of the E and J genomes was not supported from their C-banding patterns. Four species sharing the S genome, A. spicatum, A. libanoticum, A. ferganense, and A. stipifolium had C-band patterns similar to one another, although C-bands were less prominent in A. stipifolium than others.Key words: C-banding, karyotype, wheatgrass, cytology.
Chromosome location of genes controlling aluminum tolerance in wheat, rye, and triticale
Authors: Aniol A. , Gustafson J. P.
Published: November 2014

'Chinese Spring' wheat nullisomic–tetrasomic and ditelosomic lines were used for the identification of Aluminum-tolerance genes in wheat (Triticum aestivum L. em Thell.). Rye additions and substitutions in different wheat varieties were used for the identification of aluminum-tolerance genes in rye (Secale cereale L.). The point where concentrations of aluminum caused irreversible damage to the root apical meristems on exposure for 24 h at 25 °C was the measure of aluminum tolerance. Genes for aluminum tolerance in the medium-tolerant wheat variety 'Chinese Spring' were found to be localized in chromosome arms 6AL, 7AS, 2DL, 3DL, 4DL, and 4BL, and on chromosome 7D. Major genes for tolerance in rye seem to be located on 3R and 6RS, with other genes on 4R. The expression of aluminum-tolerance genes located on rye chromosomes incorporated into sensitive wheat was often suppressed by the action of unknown genes in the wheat background.Key words: Triticum, Secale, aluminum tolerance, additive effects, polygenes.
Composition nucléotidique de l'hétérochromatine constitutive de Pleurodeles waltlii
Authors: Bailly Simone
Published: November 2014

Complementary to previous works implying other staining or labeling techniques, this study used chromomycine A3, a specific fluorochrome for G and C bases, to show that in Pleurodeles waltlii Michah. (Amphibian, Urodele) the mitotic chromosome specific heterochromatin consisted of a DNA particularly rich in either of the two types of bases and the near constant presence of argyrophilic proteins. The more the DNA was rich in A and T bases, the more the argyrophilic proteins were abundant.Key words: chromomycine A3, staining, heterochromatin, Pleurodeles, banding.[Translated by the journal]
Meiotic pairing of specific chromosome arms in triploid rye
Authors: Benavente Elena , Orellana Juan
Published: November 2014

From the meiotic configurations at metaphase I of triploid plants it is possible to estimate the frequency of trivalent pairing (f) at pachytene. Although the meiotic pairing frequencies for specific chromosome arms (detected by C-banding) could not always be estimated owing to restrictions of the model, a good fit between observed and expected values was generally found. One case of preferential pairing between heteromorphic chromosome arms was observed. Heterochromatin apparently does not play any role in determining pairing preferences.Key words: triploid rye, C-heterochromatin, meiotic pairing.
Complementary genes for reaction to Puccinia recondita tritici in Triticum aestivum. II. Cytogenetic studies
Authors: Singh R. P. , McIntosh R. A.
Published: November 2014

Two complementary genes, A and B, conferring resistance to Puccinia recondita tritici in various wheats were located in chromosomes 4Aβ and 3BS, respectively. In one study gene B showed recombination of 33.6 ± 4.1% with the centromere, and was independent in a second study. Gene B was the same as that designated Lr27. A new designation, Lr31, is proposed for gene A. Both Lr27 and Lr31 must be present for the expression of resistance.Key words: leaf rust, monosomic analysis, aneuploids, wheat.
N-banding analysis of rye chromosomes and the relationship between N-banded and C-banded heterochromatin
Authors: Schlegel R. , Gill B. S.
Published: November 2014

Three of the seven chromosomes of rye (Secale cereale L.) 2R, 3R, and 6R have been identified individually by their N-banding pattern. Each of the N-banded chromosomes possesses a single band which is seen as one dot on each chromatid. Although the bands correspond with particular intercalary C-bands, they were found to be different from the remaining C-bands by sequential C- and N-banding analysis and thus reveal the heterogeneity of rye heterochromatin. It is described as C-banding and N-banding positive heterochromatin (C+N+). Similar to wheat and barley, the N-bands in rye appear to correspond to sites of (GAA)m (GAG)n sequence satellite DNA. In chromosome identification, the N-bands can be used as additional markers for the long arm of chromosome 2R (2RL), the short arm of chromosome 3R (3RS), and the long arm of chromosome 6R (6RL).Key words: heterochromatin, nonhistone proteins, banding, wheat–rye addition lines, rye.
Genetics of Glossina morsitans morsitans (Diptera: Glossinidae). X. A mutant (sabr) having long scutellar apical bristles in females
Authors: Gooding R. H.
Published: November 2014

A line of Glossina morsitans morsitans Westwood was established in which females have scutellar apical bristles approximately three times as long as normal. In other respects the flies appear normal. The mutant allele, sabr, is recessive to the wild-type allele. The locus for sabr is located in linkage group III, 50 or more map units from the locus for malic dehydrogenase. Scutellar apical bristles in mutant flies are longer in flies emerging from puparia maintained at 30 °C than in flies emerging from puparia maintained at 25 °C.Key words: Glossina, mutation sabr, bristle length.
Effect of selection for dichlorodiphenyltrichloroethane (DDT) resistance on the uptake and breakdown of DDT in Aedes aegypti L.
Authors: Rathor H. R. , Wood R. J.
Published: November 2014

Aedes aegypti larvae and adults were selected to high levels of resistance with dichlorodiphenyltrichloroethane (DDT) along separate lines. The larval-selected line showed three responses associated with larval resistance: (i) increased detoxication of DDT by dehydrochlorination to dichlorodiphenyldichloroethane DDE (demonstrated both in vivo and in vitro), (ii) increased tolerance to unmetabolised ("residual") DDT and, (iii) a reduction in uptake of DDT. Larval selection caused very little change in adult resistance or the uptake of DDT by adults, but there was an increase in dehydrochlorination. In the adult-selected line dehydrochlorination was increased by selection and was significantly correlated with resistance.Key words: DDT, DDE, resistance, Aedes aegypti.
Interspecific hybrids involving the perennial oat species Avena macrostachya
Authors: Leggett J. M.
Published: November 2014

The chromosome pairing affinities and some morphological comparisons are described in two hybrids involving the autotetraploid perennial oat species Avena macrostachya, the hexaploid cultivated oat species Avena sativa, and the tetraploid oat Avena murphyi. Chromosome pairing in the hybrids indicates that some homology between the chromosomes of the three species exists, but that it may be masked by the preferential pairing of the chromosomes from the A. macrostachya parent.Key words: Avena, meiosis, hybridization, phylogeny.
Meiosis readiness in Lilium
Authors: Walters Marta Sherman
Published: November 2014

It was observed in five cultivars and two hybrids of Lilium that premeiotic prophase is retarded in anthers approaching meiosis. The occurrence of premeiotic despiralization was related to the degree of retardation of premeiotic prophase. It is proposed that meiosis is initiated by stimuli arising outside the premeiotic cells. It is suggested that an accumulation of meiosis-inducing substances in the cytoplasm of the premeiotic cells causes prophase to slow down; when a critical level ("meiosis readiness") is reached, mitotic division is no longer possible and cells in premeiotic prophase despiralize to interphase.Key words: meiotic prophase, Lilium, meiotic readiness, premeiotic despiralization.