bluuebunny/crossref_metadata_2025 huggingface dataset:
MUTATION BREEDING AND THE MUTANT SECTOR PROBLEM IN ARABIDOPSIS
Authors: Harle J. R.
Published: November 2014

In reply to the objections raised by Redei (1974), the 34:1 segregation ratios of Harle (1972), which had been interpreted as indicating a "germ line" consisting of 8 or 9 cells in the resting Arabidopsis seed, were reexamined in comparison with the 7:1 ratios and 1 or 2 cells found by other workers. The difference was not caused by prolonged exposure of successive cell generations, as the first cell division in germinating seeds occurred only after 39 hours, while the half life for the decomposition of the mutagen (diethyl sulfate) was one hour. The new method for calculating mutation frequencies also did not account for the difference, as the use of the standard method produced almost the same conclusions. The difference found could be ascribed to the use of viable mutations in the calculations, rather than the chlorophyl-deficient and embryonic-lethal mutations normally used in experimental plant mutagenesis. The suggested modification of mutation breeding procedures was reaffirmed.
THE CYTOLOGY OF STELLARIA LONGIPES
Authors: Chinnappa C. C. , Morton J. K.
Published: November 2014

Stellaria longipes Goldie s.1. is a polyploid species complex with euploid and aneuploid chromosome numbers ranging from 2n = 51 to 107, the most frequent being 52, 78 and 104. Almost all the cytotypes show a near normal pollen and seed production and fertility. Meiotic irregularities in most plants are few and confined to the occurrence of a small number of univalents, trivalents and multivalents. Crosses between the main cytotypes are readily produced and usually show a near normal level of fertility in pollen and seed. All the naturally occurring cytotypes, together with several additional ones, have been produced in the artificial crosses. During pollen formation in some of the artificial hybrids, as well as in wild plants, a varying number of fertile monads and diads are produced. It is concluded that the range of chromosome numbers occurring in nature has arisen by hybridity between octoploids (2n = 104) and tetraploids (2n = 52), though it is probable that many of these hybrids are not of recent origin. The distribution of the cytotypes is discussed in relation to glaciation and it is noted that the octoploid tends to predominate near the edge of the range of distribution.
INFLUENCE OF SOURCE OF WHEAT CYTOPLASM ON THE NATURE OF PROTEINS IN HEXAPLOID TRITICALE
Authors: Hsam S. L. K. , Larter E. N.
Published: November 2014

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to study seed proteins in 4 pairs of reciprocal F1 isogenic hybrids of hexaploid triticales differing only in their source of cytoplasm. One member of each reciprocal pair possessed the cytoplasm of hexaploid (6x) wheat (Triticum aestivum L. em. Thell), the other, the cytoplasm from tetraploid (4x) wheat (T. turgidum L). Qualitative as well as quantitative differences were observed in the electrophoretic patterns of the albumins and globulins. High molecular weight proteins (> 34,000 daltons) were synthesized in triticale with 6x wheat cytoplasm in greater quantity than in triticale with 4x wheat cytoplasm. Differences in the patterns of gliadin and reduced glutenin of the reciprocal triticale populations were quantitative. The relevance of these findings to seed development in triticales is discussed.
GENOME ANALYSIS OF HORDEUMJUBATUMANDH.COMPRESSUM
Authors: Starks Gilbert D. , Tai William
Published: November 2014

On the basis of the chromosome behavior of a backcross between a colchicine-induced amphiploid (6x) from a cross between Hordeum jubatum L. and H. compressum Griseb. and H. jubatum (4x), the following genome relationship between H. jubatum, H. compressum and closely related species is suggested: H. jubatum, AAA′A′, H. brachyantherum, A A A′A′, H. californicum, A A, and H. compressum, A′A′. Also, an argument is proposed for genetic control of chromosome pairing.
AVENA CANARIENSIS: MORPHOLOGICAL AND ELECTROPHORETIC POLYMORPHISM AND RELATIONSHIP TO THE A. MAGNA–A. MURPHYI COMPLEX AND A. STERILIS
Authors: Craig Iris L. , Murray Beatrice E. , Rajhathy Tibor
Published: November 2014

Avena canariensis, a recently discovered oat species from Fuerteventura in the Canary Islands, has distinctive ecotypes, is polymorphic in morphological traits and in protein and esterase patterns forming clinal areas within the elevation gradient on the island. A comparison of leaf esterase patterns with that of other species provides evidence favoring A. canariensis as donor of the A genome in the A. magna–A. murphyi–A. sterilis evolutionary cluster.
HAPLOID PLANTS (2n = 21) FROM in vitro ANTHER CULTURE OF TRITICUM AESTIVUM
Authors: Craig Iris L.
Published: November 2014

Nine haploids (2n = 21) of Triticum aestivum L. (cv. Pitic–62) were obtained by in vitro anther culture, utilizing the medium described by Ouyang et al. (1973).
PROTOPLAST AND CELL CULTURE METHODS IN SOMATIC HYBRIDIZATION IN HIGHER PLANTS
Authors: Gamborg Oluf L. , Constabel F. , Fowke L. , Kao K. N. , Ohyama K. , Kartha K. , Pelcher L.
Published: November 2014

New advances have been made in the development of procedures for somatic cell hybridization in plants. The techniques involve plant tissue culture, whereby it is possible to grow cells of most plants under sterile conditions in chemically defined media. Somatic hybridization can be achieved by cell fusion. The procedure consists of a series of steps beginning with the production of plant protoplasts obtained by enzymatic removal of the cell walls. Hybrid cells from heterokaryons of a wide range of plant genera and families have been obtained after protoplast fusion and subsequent culturing, e.g. soybean-barley. An alternate method for transferring genetic information consists of feeding isolated DNA to protoplasts or to plant organs. Correction of biochemical lesions has been possible by such procedures. Some success has been achieved in growing plants from cultured cells and protoplasts. These methods may then be applied to obtain hybrid plants. Intergeneric hybrid plants thus obtained can subsequently be utilized in conventional plant breeding programs, and for genetic analyses.
CHROMOSOMES OF THE MEXICAN PLATEAU MOUSE, PEROMYSCUS MELANOPHRYS, AND A NEW SEX DETERMINING MECHANISM IN MAMMALS
Authors: Zimmerman Earl G.
Published: November 2014

A chromosomal analysis of 86 specimens of Peromyscus melanophrys reveals a unique type of chromosomal difference between males and females Females possess three large pairs of subtelocentric autosomes, two pairs of small submetacentric autosomes, and 18 pairs of acrocentric autosomes. The X chromosomes are also subtelocentric. Males possess a similar karyotype with a subtelocentric X chromosome, a minute Y chromosome, and two unmatched autosomes, a large subtelocentric and a large acrocentric. Both sexes have a diploid number of 48. Studies from meiosis and autoradiography indicate that a portion of the original Y chromosome has been translocated to an autosome resulting in a new multiple sex determining mechanism in mammals, an X1X1X2X2/X1X2Y1Y2 system.
GROWTH DEPENDENT 2-DEOXY-D-GLUCOSE UPTAKE IN TRANSFORMED AND NORMAL MOUSE CELLS
Authors: Martin-De Leon Patricia A. , Mukherjee Barid B.
Published: November 2014

The rates of uptake of 2-deoxyglucose were studied in a) 15-day BALB/c and AKR embryonic cells, b) adult BALB/c lung fibroblasts and c) virally-transformed cell lines derived from a clone of BALB/c cells. At high cell densities in confluent cultures of non-transformed cells the rates of uptake were three to seven times lower than those in transformed cells at the equivalent densities. Both non-transformed and virally-transformed cell cultures showed density-dependent inhibition of 2-deoxyglucose uptake. However, inhibition was only slight in SV40 (SVT2) and Kirsten sarcoma virus-transformed (K-A31) cells in which uptake rates decreased 2.3– and 2.5– fold respectively during a 12-fold increase in cell densities. For an almost similar increase in cell density, in unestablished adult embryonic BALB/c fibroblasts, the rate of uptake decreased 8-fold. Incorporation of H3-thymidine (an indication of growth rate) occurred at a higher rate in transformed than in contact-inhibited cells. Two hours after serum stimulation of contact-inhibited AKR cells there was approximately 50% increase in the rate of 2-deoxyglucose uptake. The results confirm previous findings that the increased uptake of 2-deoxyglucose by virally-transformed cells may be due to their growth and division and not necessarily to the direct expression of the viral genome.
TRANSLOCATIONS, INVERSIONS AND CORRELATION OF LINKAGE GROUPS TO CHROMOSOMES IN THE MOSQUITOCULEX PIPIENS FATIGANS
Authors: Bhalla Satish C. , Cajaiba Antonio C. I. , Carvalho Wanda M. P. , Santos Joselita M.
Published: November 2014

Eight sex-linked translocations and two pericentric inversions were artificially induced and isolated in the mosquito Culex pipiens fatigans. Following extensive studies on the genetics and cytology of these aberrations, correlations between the three pairs of chromosomes and the three linkage groups were established. Chromosomes 1 (shortest), 2 (longest) and 3 (intermediate) are correlated to linkage groups I, II and III respectively. These conclusions are in conflict with an earlier publication. A secondary constriction was observed on the m (but not on the M) chromosome near the centromere. Its significance is not yet clear. The genetic and cytological data indicate that the gene y may be located on the long arm and the gene ru on the short arm of chromosome 2.
HETEROCHROMATIN AND MULTIPLE INVERSIONS IN A DROSOPHILA CHROMOSOME
Authors: Baimai Visut
Published: November 2014

A chromosomal polymorphism is described from a Maui (Hawaii) population of D. disjuncta. The acquisition of an extra heterochromatic segment in a mitotic chromosome is specifically associated with the presence of multiple inversions in the same chromosome. This suggests the possible effect of a chromosomal break-point within the area of centromeric heterochromatin in causing an increase in the amount of repetitive DNA. The possibility exists that the extra heterochromatin may play a role in the suppression of gene recombination in a certain region of the chromosome and/or in strengthening pairing of the inversion-laden chromosome with its normal homologue. This may reduce the chances of sterility due to nondisjunction during meiosis.
THE EFFECTS OF URETHANE, SODIUM MONOHYDROGEN ARSENATE AND SELENOCYSTINE ON CROSSING-OVER IN DROSOPHILA MELANOGASTER
Authors: Ahmed Zia U. , Walker G. W. R.
Published: November 2014

The effects of 0–25 mM urethane, 0–50 μM selenocystine and 0–100 μM sodium monohydrogen arsenate on marker-exchange frequencies have been studied along a region of the X chromosome of Drosophila melanogaster marked by y, cv, v and f. Clear and consistent effects seen in concentration curves were usually but not always found significant in analyses of variance. Urethane concentration curves rose to a higher level at 0.5 to 3 mM and dropped to control levels between 10 and 25 mM. It is proposed that this reversibility was due to a competition between two categories of lesions mimicking natural recombination sites, those on unpaired regions of the chromosome competing with those on already paired regions for recombination-repair enzymes. Selenocystine affected exchange frequencies mainly toward the ends of the unmarked region, especially y – cv, negatively from 2 to 10 μM and positively above 10 μM. These effects are interpreted as being mediated by selenocystine control over restriction of synaptic pairing to terminal regions, especially y – cv. Interactions between urethane and selenocystine in two-chemical treatments satisfactorily support the above explanations for both the urethane and selenocystine effects. Sodium monohydrogen arsenate effects, tentatively attributed to the arsenate ion, differed markedly from those of the other chemicals: "arsenate" concentration curves for single-exchange classes tended to be broadly convex and those for double-exchange classes concave, while interactions with urethane tended to be synergistic or neutral except in one exchange class (that for single exchange in y – cv). No satisfactory explanation of the arsenate effects has yet been found. At 25 mM only, urethane caused male-specific, 95% pupal mortality.
INHERITANCE OF THREE GENES FOR MORPHOLOGICAL CHARACTERS IN PETUNIA HYBRIDA IN CROSSES WITH FOUR PETUNIA SPECIES
Authors: Sink Jr. K. C.
Published: November 2014

Three inbred marker lines of Petunia hybrida Vilm. carrying independently inherited monogenic characters (apt, apetalous flower; D flower doubleness; G grandiflora plant and flower) were hybridized with the petalous, single-flowered, multifloral Petunia species, P. axillaris (Lam.) B.S.P., P. inflata Fries, P. violacea Lindl., and P. parodii W.C.S. to obtain information about the genetic affinities between these species and the cultivated Petunia. Each of the three genetic characters was determined to be monogenetically inherited in immediate progenies of crosses with the four Petunia species, although the testcross and F2 ratios were aberrant for segregation of flower doubleness following crosses with P. inflata and P. violacea. This could be due to interspecific chromosomal divergencies, or segregation of modifiers of D. The results are generally consistent with the view that a large degree of genetic homology exists in the genus Petunia.
FEULGEN HYDROLYSIS AND CHROMOSOME BANDING IN CHILOCORUS (COLEOPTERA: COCCINELLIDAE)
Authors: Ennis T. J.
Published: November 2014

Prolonged Feulgen hydrolysis of chromosomes of Chilocorus orbus Csy. and C. stigma Say produces banding patterns that are the reverse of those revealed with quinacrine; brightly fluorescing regions are unstained, but nonfluorescent regions remain relatively darkly stained. This differential reactivity at hydrolysis times that otherwise yield intense Feulgen staining confirms the need for caution in the determination of DNA values with the Feulgen reaction in material with well-defined quinacrine bands. The coincidence of DNA-specific Feulgen bands with Q-, G-, and C-bands supports the view that, in Chilocorus at least, bands reflect differences in DNA composition along the chromosome.
LOCATING THE CHLOROPHYLL MUTATION,av, IN OATS BY USING TELOCENTRICS
Authors: Sadanaga K.
Published: November 2014

Alboviridis (av), a chlorophyll mutation in hexaploid oat, Avena sativa L., was located on the long arm of a subterminal monosome, ST-20. Crossing over between the locus and centromere was 4.0 ± 3.8% and 4.6%, as calculated from the backcross and F2data, respectively. The transmission of the telosome, as calculated from the backcross data, was 42% through the egg and 0% through the pollen. The transmission of the telosome, as calculated from the F2population, was 1% through the pollen.
CYTOGENETIC STUDIES IN THE GENUS PERSEA (LAURACEAE). I. KARYOLOGY OF SEVEN SPECIES
Authors: V. Armando Garcia
Published: November 2014

Chromosome number determinations were made on 137 collections of seven Persea species. Persea americana Mill., P. schiedeana Nees, and P. aff. cinerascens Rands, had a diploid number of 24 as reported earlier. The first chromosome counts for four species are reported. Persea hintonii Allen (2n = 48) is the first tetraploid species found in this genus. Persea indica (L.) Spreng. (2n = 24) is the first Old World species to have its chromosome number reported. Persea donnell-smithii Mez and P. pachypoda Nees also have the diploid number (2n = 24). One triploid (2n = 36) and one tetraploid (2n = 48) individual were found in P. americana. Based on stomatal size, their maternal plants were considered to be triploid and diploid, respectively.This is the first karyotype study in Persea and also in the family Lauraceae. The karyotype in Persea is asymmetric. The chromosomes range in size from 2.3 µm to 6.1 µm. Persea americana has one pair of satellited chromosomes, which is the largest pair, two metacentric pairs and nine submetacentric pairs. Two of the submetacentric pairs are highly heterochromatic and both are attached to the nucleolus. All the other species have karyotypes very similar to P. americana.
THREE MECHANISMS OF 2nPOLLEN FORMATION IN DIPLOID POTATOES
Authors: Mok D. W. S. , Peloquin S. J.
Published: November 2014

Three mechanisms of 2n pollen formation observed in diploid hybrids between Solatium tuberosum Group Phureja (2x) and haploids of S. tuberosum Group Tuberosum (4x) are termed parallel spindles (ps), premature cytokinesis 1 (pc 1) and premature cytokinesis 2 (pc 2). A II spindles are parallel to each other in many cells of clones producing 2n pollen by ps. A single cleavage furrow follows and forms a dyad which generates two 2n microspores. The other two mechanisms, pc 1 and pc 2, produce 2n pollen by omission of the second meiotic division. Premature cytokinesis 1 (pc 1) involves asynchronized movement of bivalents to and from the M I plate and falling apart of chromatids at T I. A cleavage furrow follows the first meiotic division, no second division occurs and products of meiosis are dyads. Premature cytokinesis 2 (pc 2) exhibits no abnormalities at the first meiotic division. However, cytokinesis occurs prematurely at P II, no second division occurs, and only dyads are formed. Genetic data suggested that these three mechanisms may be controlled by single loci, and are inherited independently as simple recessives.
GROWTH PATTERNS OFADENINE-3B;SUPERSUPPRESSORSTRAINS OFNEUROSPORA CRASSA
Authors: Griffiths A. J. F.
Published: November 2014

The interaction between several suppressible ad-3B alleles and several supersuppressor genes has been examined both quantitatively and qualitatively in a tetrad analysis. Quantitatively, there is a good deal of variation in mean growth rates of cultures showing supersuppression: part of this variation can be attributed to variation in the suppressibility of ad-3B alleles, part to variation of suppression efficiency of ssu alleles, and part to the action of modifying genes. Qualitatively, ad-3B; ssu cultures nearly always show cyclic stop-start growth patterns. Escape from stop-start growth to wild-type growth is common.
INSECT CHROMOSOME BANDING: TECHNIQUE FOR G- AND Q-BANDING PATTERN IN THE MOSQUITOAEDES ALBOPICTUS
Authors: Steiniger Gerald E. , Mukherjee Asit B.
Published: November 2014

A modified technique is described for the production of clear G- and Q-bands of somatic metaphase chromosomes of the mosquito, Aedes albopictus Skuse.
THE INTERACTIVE EFFECT OF ULTRAVIOLET IRRADIATION AND 5-BROMOURACIL AT THE RIB-1 LOCUS IN NEUROSPORA CRASSA
Authors: Nemerofsky Arnold
Published: November 2014

5-Bromouracil (5-BU) was shown to enhance reverse mutation rates when added to conidia of a rib-1 strain of Neurospora crassa previously irradiated with ultraviolet light. A comparison is presented between various incubation intervals in the presence and absence of 5-BU while varying the UV dose. An increase in mutation frequency ranging from 0.028–2.05 × 102 times greater than the spontaneous frequency, UV frequency alone or 5-BU frequency alone was observed when UV irradiation and 5-BU were combined.
KNOWLEDGE, POWER, MAN AND JUSTICE: ETHICAL PROBLEMS IN BIOMEDICAL RESEARCH
Authors: Reed James
Published: November 2014

This essay attempts to raise some ethical problems related to biomedical research as they revolve around the issues of knowledge, power, man and justice. The arguments connected with such matters will not provide answers, but rather soundings for unchartered waters. Much more can and needs to be developed about the nature of knowledge and the politics of its use and abuse. A more detailed analysis and critique of man's nature might be engaged in to determine many concerns, not least of which is whether we can even talk about human nature. The idea of justice is elusive at the best of times and is particularly complicated at a time in history when social and economic interpretation is so complex. Much more must be debated before we can produce a detailed map. Fundamental to all of this, though, hopefully will be a dialogue among the many disciplines concerned with human research. We can not afford to work in isolation. The consequences of our decisions are too great.
MEIOTIC PAIRING BETWEEN SINGLE CHROMOSOMES OF DIPLOID AGROPYRON ELONGATUM AND DECAPLOID A. ELONGATUM IN TRITICUM AESTIVUM
Authors: Dvořák J.
Published: November 2014

It is shown that meiotic pairing between single chromosomes of closely related taxa can be studied in hybrids between alien addition and substitution lines. Using this technique, two chromosomes of diploid A. elongatum which appear to be homoeologous with wheat chromosomes of groups 6 and 7 were shown to pair with chromosomes of decaploid A. elongatum which are also homoeologous with wheat chromosomes of groups 6 and 7. Hence, pairing of these chromosomes verified the suggested homoeology among these chromosomes.Meiotic pairing was also studied in 2 hybrid progenies which carried specific telosomes of diploid A. elongatum in addition to a set of 7 Agropyron chromosomes which came from decaploid A. elongatum. The telosomes paired with the decaploid A. elongatum chromosomes in these hybrids. Hence, four chromosomes of diploid A. elongatum were shown to pair in common wheat with chromosomes of decaploid A. elongatum. Since pairing between diploid A. elongatum and decaploid A. elongatum chromosomes was generally low, it is suggested that the chromosomes assigned to the same group are not homologous but rather closely homoeologous.
GENETIC CONTROL OF SUSCEPTIBILITY TO HYDROXYPROLINE INDROSOPHILA
Authors: Rapport Ellen W.
Published: November 2014

Hydroxyproline (OHP) is known to produce morphological abnormalities in susceptible Drosophila. In some, OHP prevents head eversion during pupation producing a cryptocephal (crc) phenocopy, others fail to fully stretch legs and wings producing a shortened distance between these appendages (LWD). In this paper the genetic basis of susceptibility to OHP is explored and compared to the control of susceptibility to glucosamine (GA) which also produces a crc phenocopy. The data suggest that genes providing resistance to the effects of GA are different from those conferring resistance to OHP. Furthermore, genes providing resistance to the crc effects of OHP appear to be different from those controlling resistance-to the LWD effects. Intrastrain gene coadaptation also seems to be important in resistance to OHP. The relevance of these results to the problem of the genetic control of developmental buffering is briefly discussed.
A STUDY OF VARIATION IN FRUIT YIELD AND RELATED CHARACTERS IN TWO DIALLELS OF THE LOWBUSH BLUEBERRY, VACCINIUM ANGUSTIFOLIUM AIT.
Authors: Aalders Lewis E. , Hall Ivan V.
Published: November 2014

Two diallels, one involving 5 parents and a second involving 8 parents were evaluated for 3 years each. In the 5-parent diallel, date of harvest, yield of ripe fruit, weight per berry, and area covered by one plant were evaluated. Of these, weight per berry had by far the greatest genetic and additive components of variation whereas these components for yield were very low. In the 8-parent diallel, the same variables were evaluated with the addition of berry color, plant vigor and log number of berries. Weight per berry and berry color had large genetic and additive components whereas yield of ripe fruit, plant vigor and log number of berries had large environmental components of variation.
A KARYOLOGICAL STUDY OF NINE SPECIES OF TORYMUS (HYMENOPTERA: TORYMIDAE)
Authors: Goodpasture Carll , Grissell E. E.
Published: November 2014

Haploid karyotypes composed of 5 metacentrics (T. umbilicatus, T. koebelei), 4 metacentrics plus 2 telocentrics (T. tubicola), 5 metacentrics plus 1 telocentric (T. warreni), 5 metacentrics plus 1 acrocentric (T. baccharidis, T. vesiculi, T. occidentalis, T. capillaceus), and 6 metacentrics (T. californicus) are described. Five metacentrics are postulated as ancestral for the Torymidae, based on karyotype frequency for the family and Robertsonian relationships among taxa. Karyotypes of 5 metacentrics or 5 metacentrics plus 1 telocentric are considered ancestral for the genus Torymus. Derived karyotypes have apparently evolved independently in several lineages within the genus.
LINKAGE OF THE GENES FOR DDT AND DIELDRIN RESISTANCE IN LARVAE OF THE MOSQUITO AEDES AEGYPTI
Authors: Hitchen Judith M. , Wood R. J.
Published: November 2014

The DDT resistance gene RDDT1, and the dieldrin resistance gene Rd1 have been mapped on linkage group II with respect to visible markers, in the mosquito Aedes aegypti L. The best interpretation of the data gives the order wa – Rd1 – ds – RDDT1 – s – y but wa – Rd1 – ds – y – s – RDDT1 is also possible, h is very loosely linked with RDDT1. The length of the linkage group has been considerably extended from previous studies.
THE EFFECT OF CHLORAMPHENICOL AND CYCLOHEXIMIDE ON MEIOTIC ZOOSPOROGENESIS AND MITOTIC GAMETOGENESIS INULVA MUTABILIS
Authors: Hoxmark Rolf Christian
Published: November 2014

Ulva mutabilis cells induced to form zoospores or gametes were exposed to chloramphenicol or cycloheximide during the 48 hours preparatory period. Chloramphenicol inhibited protein and RNA accumulation to the same degree at all concentrations, and appeared to have a general toxic effect. Cycloheximide at low concentrations inhibited primarily protein accumulation, while at higher concentrations it had also an effect on the net synthesis of RNA. Most of the inhibited cells were found in interphase, but a small percent of vegetative mitoses were observed and may indicate a return to this type of division. The gametophyte appeared to be more sensitive to chloramphenicol than the sporophyte. The effect of cycloheximide on the two processes seems to be more or less the same. A transition period, after which the sporulation process could no longer be inhibited, was found about 10 hours before the cells entered meiotic prophase in zoosporogenesis.
HETEROSIS, SEX AND MATERNAL INTERACTIONS IN CROSSES AMONG INBRED LINES OF MICE
Authors: White J. M. , Jamison M. G. , Vinson W. E.
Published: November 2014

All possible crosses and reciprocals were made among four inbred lines [Formula: see text] developed from 12 generations of full-sib mating. All lines originated from a common outbred base population of ICR-albino mice. Data were obtained from 356 litters containing 2,734 mice to evaluate heterosis, reciprocal effects, sex effects and their interactions as they affect body weight and weight gain. Heterosis was significant for most of the postweaning traits (42- and 56-day weight and gain from 21 to 42 days). Nonadditive gene action may have included overdominance and epistasis since both reciprocal linecrosses were generally heavier than those of the better inbred lines. Although significant differences in reciprocals and inbred lines were not frequent, there were sufficient differences to indicate that lines varied in the fixation of loci during inbreeding. Sex-heterosis interactions were significant for 12 of 30 possible cases. However, eight of the 12 significant interactions occurred in crosses involving only one of the lines. The interactions were of the divergent type and arose from males exhibiting more heterosis than females. Overdominance in genes on the sex chromosomes modified by other loci (epistasis) was proposed as a possible explanation for these results. Some sex-linkage affecting growth was evident from the interaction of sex with reciprocal effects.
CHROMOSOME DOUBLING OF BARLEY HAPLOIDS BY NITROUS OXIDE AND COLCHICINE TREATMENTS
Authors: Subrahmanyam N. C. , Kasha K. J.
Published: November 2014

Hybridization of Hordeum vulgare L. (2n = 14) with H. bulbosum L. (2n = 14) results in a high frequency of haploids of H. vulgare through selective elimination of H. bulbosum chromosomes. Doubled haploids were produced by nitrous oxide (N2O) or 0.1% colchicine with and without dimethyl sulfoxide (DMSO) treatments. Pollinated florets (vulgare × bulbosum) were treated with N2O under 21.1 × 10−3to 42.2 × 10−3 kg/m2pressure (30 to 60 psi) and the frequency of doubled haploids ranged from 0 to 100%, depending upon pressure and duration of exposure. However, the frequency of seedlings from the most effective N2O doubling treatment was very low (0.5%) whereas 17% of the florets pollinated in the controls resulted in seedlings. Of the haploid seedlings treated with either 0.1% colchicine or colchicine plus DMSO, doubled sectors occurred in 37.4 and 55.8% respectively. Seed was also obtained from 3% of the untreated plants indicating a low frequency of natural chromosome doubling. The proportion of doubled tillers per plant was 61.6% in colchicine plus DMSO treatments and 30.8% in the colchicine treatments. Colchicine plus DMSO was the most efficient treatment for doubling barley haploids during early stages of development.
POLYPLOIDY AND MUTATIONS INDUCED IN APRICOT BY COLCHICINE TREATMENT
Authors: Lapins K. O.
Published: November 2014

Colchicine treatment of three diploid apricot (Prunus armeniaca L.) cultivars produced tetraploids, aneuploids and diploid mutants. The tetraploids were sterile to a high degree; their fruit was mostly large, but uneven in size. Meiotic divisions were irregular; over 60% of quartets had more than 4 microspores and only 13 to 21% of pollen was stainable and normal in size and shape. Among the aneuploids, very typical and possibly identical trisomics were found in all three cultivars. Three single trisomics and one double trisomic were highly sterile; they produced very little stainable pollen and set practically no fruit. In diploid mutants, fertility ranged from low to normal. Some potentially useful mutants in time of maturity of fruit were recorded.
MISDIVISION OF AN AGROPYRON CHROMOSOME
Authors: Sharma D. C. , Morris R. , Schmidt J. W.
Published: November 2014

Agrotricum lines, in which an Agropyron chromosome with genes for stem- and leaf-rust resistance replaced wheat chromosome 6D, have been used in breeding programs at the University of Nebraska-Lincoln. The 42-chromosome Agrotricum lines were developed by an initial cross between common wheat (Triticum aestivum) and Agropyron elongatum (2n = 70), followed by backcrosses to various wheat cultivars. These lines were crossed as male parents with Chinese Spring monosomic 6D as female, to obtain plants monosomic for the Agropyron chromosome (20″ + 1′Ag). Microsporocytes in these monosomic alien substitution plants were examined at the first and second divisions of meiosis. The Agropyron chromosome is a small, nearly isobrachial chromosome. It misdivided in 40.1% of the cells at the first division (AI-TI). Meiotic configurations of the misdividing chromosome indicated that the centromere of the Agropyron chromosome is divisible into four functional units (telocentrics) at the first division. Only 11.6% of the cells with lagging chromosomes showed misdivision at the second division (AII-TII) of meiosis. The expected frequency of micronuclei from AII-TII data was compared with that observed at the quartet stage. It was concluded that 24% of the lagging whole or telocentric chromosomes were included in the second division nuclei, indicating that some of the telocentrics may be transmitted. The relatively high rate of misdivision of the Agropyron chromosome considerably increases the chances of recovering telo- and isosomic lines for each arm. Rust tests of these lines will provide evidence for the locations of genes for stem- and leaf-rust resistance on specific arms of this chromosome.
GENETIC CONTROL OF VIRULENCE IN USTILAGO HORDEI. IV. DUPLICATE GENES FOR VIRULENCE AND GENETIC AND ENVIRONMENTAL MODIFICATION OF A GENE-FOR-GENE RELATIONSHIP
Authors: Ebba Tadessa , Person Clayton
Published: November 2014

Genotype V2v2 of Ustilago hordei was transferred to a new genetic background and its gene-for-gene interaction with genotype R2R2 of barley cultivar Excelsior was studied in two different environments. This gene-for-gene interaction was found to be subject to both genetic and environmental modification. The analysis also revealed that virulence which is specific to cultivars Keystone and Himalaya can be controlled by duplicate recessive genes present at either one of two genetic loci of U. hordei.
CHROMOSOME ASSOCIATIONS AT PACHYTENE IN THE INTERCHANGE HETEROZYGOTES OF SORGHUM BICOLOR
Authors: Reddi V. R. , Rao E. V. V. Bhaskara
Published: November 2014

Six gamma ray induced interchange heterozygotes of Sorghum bicolor (L.) Moench were examined at pachytene to study the pairing associations and to identify the chromosomes involved in each. Length measurements of the translocated and nontranslocated paired arms have been obtained. The results reveal no particular preference for the break points to lie either in the heterochromatic or euchromatic regions. The translocations were probably induced on a random basis, effecting many of the chromosomes in the complement.
CHROMOSOMAL ABNORMALITIES AND THE MORPHOLOGY OF MOUSE SPERM HEADS
Authors: Wyrobek A. J. , Heddle J. A. , Bruce W. R.
Published: November 2014

In the mouse, numerous mutagens, teratogens and carcinogens have been shown to induce marked elevations in the fraction of sperm with head shape abnormalities. Since carcinogens and teratogens may act by causing genetic damage, a likely explanation of these results is that the sperm abnormalities are also caused by genetic damage. There are two more or less distinct classes of genetic damage, chromosomal aberrations and point mutations. In this paper, we provide evidence, that in general, chromosomal aberrations are not responsible for causing abnormally shaped sperm. Chromosomal aberrations could have caused abnormal sperm morphology in a number of ways. One possibility was that the mere presence of a translocated chromosome within the germ cell led to the malformation of the sperm head. A second possibility was that chromosomal imbalance, i.e., aneuploidy, duplications or deficiencies, within the spermatid or haploid cells caused abnormalities in shape. We tested these hypotheses by measuring the level of abnormally shaped sperm in mice homozygous and heterozygous for 24 various reciprocal and Robertsonian translocations. The diploid cells of these mice are known to be chromosomally balanced, containing translocated chromosomes. A predictable proportion of their gametes are, however, chromosomally unbalanced and carry translocated chromosomes. It was found that the levels of sperm abnormalities in these mice were convincingly unrelated to the levels predicted by any of the above hypotheses. Based on these results it seems that sperm abnormalities in mice are not due to the mere presence of translocated chromosomes in germ cells and also not due to chromosomal aneuploidy or duplication-deficiencies of chromosomal segments in the spermatid during development of the sperm.
PREMATURE CHROMOSOME CONDENSATION AND CHROMOSOME DESPIRALIZATION IN SYRIAN HAMSTER CELLS TRANSFORMED IN VITRO
Authors: Popescu N. C. , DiPaolo J. A.
Published: November 2014

In vitro neoplastic transformation of Syrian hamster cells by chemical carcinogens or Simian adeno-7 virus results in cell lines that have rare cells possessing some chromosomes identical to those referred to as premature chromosome condensation or despiralization. These phenomena occurred without the addition of viruses known to promote cell fusion.
COMPARISONS OF SOMATIC CROSSING OVER FREQUENCY INNICOTIANA TABACUMAND THREE OTHER CROP SPECIES
Authors: Evans David A. , Paddock Elton F.
Published: November 2014

Tobacco is compared with Glycine max, Gossypium barbadense, and Lycopersicon esculentum. In tobacco, a greater number of D spots (1.37 ± 0.092 per leaf) than of A spots (0.33 ± 0.039) was observed. Double spots were found less often (0.10 ± 0.021) than A spots. Spots occurred equally often among the youngest 4 leaves, among the oldest 4, and among the middle 12, but more often and with more variability among the middle 12. As in G. max, spots occur only on leaves of chlorophyll deficiency heterozygotes, more frequently on upper than lower surfaces, and equally often on right and left halves. Unlike G. max, spots occur more frequently, at all positions in the leaf sequence, more frequently on distal than proximal halves, and proportionally more D spots whether relative to A spots, Db spots, or their sum. Tobacco has the highest, and L. esculentum the lowest, frequencies of total spots per leaf and Db spots per leaf. L. esculentum has the highest D/A ratio. The frequency of somatic crossing over per spot-capable mitosis is established as 5.74 × 10−5in G. max and 7.70 × 10−6in tobacco.
CYTOLOGY OF BRAZILIAN PHANEROPTERIDAE (ORTHOPTERA-TETTIGONIOIDEA): A SPECIES WITH NEO XY SEX DETERMINING MECHANISM
Authors: Ferreira Amilton
Published: November 2014

The chromosome number of 10 species of Phaneropteridae are reported: Euceraia insignis Piza, Topana acquillari Piza, Picnopalpa bicordata Piza, Microcenirum lanceolatum Brunner, Pararota ferrerai Piza, Parableta bicentenaria Piza, Parableta affinis Piza, Phaneroptera exigua Piza, Hyperohora angustipennis Brunner and Mendesius albosignatus Piza. Except for Mendesius albosignatus Piza, all have 2n (♀) = 31 acrocentric chromosomes with a XO (♀), XX (♂) sex determining mechanism. The chromosome number of Mendesius albosignatus is 2n (♀) = 28. The sex chromosome mechanism is of the Neo XY (♀) type. The Neo X chromosome is submetacentric. XL is at least twice the length of XR. XR pairs over its entire length with the Neo Y; they are held by an interstitial chiasma and no sign of heterochromatin could be observed in them.
CHROMOSOME STRUCTURE INCHILOCORUS(COLEOPTERA: COCCINELLIDAE). II. THE ASYNCHRONOUS REPLICATION OF CONSTITUTIVE HETEROCHROMATIN
Authors: Ennis T. J.
Published: November 2014

Chromosome replication has been analysed in four species of Chilocorus. In C. orbus Csy., C. tricyclus Smith, and C. hexacyclus Smith, centric regions of all chromosomes are last to replicate, preceded in order by heterochromatic arms and euchromatic arms. In C. stigma Say, very late replication of centric regions can be detected only in otherwise wholly euchromatic chromosomes (= monophasics); in chromosomes with one arm heterochromatic (= diphasics), these arms are last to replicate. Based on pachytene bivalent morphology and chromosome banding patterns, and supported by autoradiographic data, models are presented for the general organisation of Chilocorus chromosomes. All chromosomes in the first three species are subdivided into euchromatic arm, centric heterochromatin, and either a second euchromatic arm (monophasics) or a heterochromatic arm (diphasics). Chilocorus stigma diphasics apparently lack distinct centric organisation, and are therefore divided into euchromatic and heterochromatic arms only.
CHROMOSOME TRANSMISSION AND MORPHOLOGY OF THREE PRIMARY TRISOMICS IN SOYBEANS (GLYCINE MAX)
Authors: Palmer Reid G.
Published: November 2014

Two primary trisomics in soybeans (Glycine max (L.) Merr.), Tri A and Tri B that arose from an asynaptic mutant, did not differ in morphology from each other or from their respective diploid sibs. The third primary trisomic, Tri C, which arose from a desynaptic mutant, showed slight morphological deviation from its diploid sib. There was no relationship between seed weight and somatic chromosome number among the progeny of the three trisomics. Self-pollination of the three trisomics yielded approximately 50% 2n + 1 offspring but only 3% 2n + 2 progeny. Intercrosses among the three trisomics gave approximately 50% 2n + 1 F1 progeny and yielded 13% 2n + 1 + 1 progeny. The rate of ovule transmission of the extra chromosome was 34% for Tri A, 45% for Tri B, and 39% for Tri C. The rate of pollen transmission of the extra chromosome was 27% for Tri A, 22% for Tri B, and 43% for Tri C. Soybeans can tolerate an extra chromosome without any appreciable detrimental effect on the gametophyte or the sporophyte. These results are in harmony with the supposed polyploid nature of soybeans.
INTERACTION OF VIRULENCE GENES IN USTILAGO HORDEI
Authors: Thomas P. L.
Published: November 2014

The genetic cause of virulence of Ustilago hordei on the cultivars Lion and Plush was attributed to a single gene, designated v6. This gene was recessive and unlinked to either v1 or v2. Dikaryons with the genotype v1v1V6v6 were virulent on Hannchen while those with v2v2V6v6 were virulent on Excelsior. However, the the combination v1v1v6v6 was required for virulence on Vantage. The resistance of other cultivars of the host was overcome by combinations of more than one virulence gene in the pathogen, indicating that some cultivars possess more than one gene for resistance.
LINKAGE DISEQUILIBRIUM BETWEEN FUNCTIONALLY RELATED ENZYME LOCI OFDROSOPHILA MOJAVENSIS
Authors: Zouros E. , Johnson W.
Published: November 2014

Gametic frequencies at four enzyme loci of the second chromosome of Drosophila mojavensis race B were obtained from six localities. The four loci were selected so that they code for functionally related enzymes: two code for esterases, one for xanthine dehydrogenase and one for acetaldehyde oxidase. In Drosophila the two latter enzymes are under the same regulatory control and their physiological functions might be related as well. Electrophoretic variants at the loci coding for these two enzymes were found not to be in pair-wise linkage equilibrium. Other pair-wise combinations were in linkage equilibrium. It is argued that selectively maintained nonrandom associations may occur frequently between linked loci, the enzymatic products of which are functionally related, share common subunits or are under the same regulatory control.
STUDIES ON THE HYPOANEUPLOIDS OF COMMON WHEAT. III. PRODUCTION OF SEXTUPLE MONOSOMICS
Authors: Shigenaga Shoji
Published: November 2014

Two kinds of sextuple monosomics for A-genome chromosomes, namely, one plant simultaneously deficient for chromosomes 1A, 2A, 4A, 5A, 6A and 7A and the other deficient for 1A, 2A, 3A, 4A, 5A and 6A, were produced in a systematic way in the variety Chinese Spring. Sextuple monosomics (15″ + 6′) were selected in the progenies of crosses between quintuple monosomics (16″ + 5′) and nullisomics (20″) which lacked the sixth pair of chromosomes. The sextuple monosomics were smaller, with reduced vigor and later maturity, compared with normal plants. They showed stable chromosome behavior in meiosis and retained fertility in both sexes. Female gametes with n = 16, 17, 18, 19, 20 or 21 produced from the quintuple monosomics functioned well in fertilization.
IDENTIFICATION OF THE EXTRA CHROMOSOMES IN GIEMSA STAINED SOMATIC CELLS OF PACHYTENE IDENTIFIED TRISOMICS OF SOLANUM CHACOENSE
Authors: Lee Heiyoung K. , Hanneman Jr. R. E.
Published: November 2014

Four secondary trisomics, identified by pachytene analysis in Solanum chacoense Bitt., were analyzed with the Giemsa stain technique. The clones V1700.8 and V1700.24 which, according to pachytene analysis, were secondary trisomics for the long and short arm of chromosome IV, respectively, were identified as secondary trisomics for the long and short arm of chromosome C, respectively, in Giemsa stained somatic cells. Clone V1700.1, a secondary trisomic for the long arm of chromosome IX, was identified as having an extra isochromosome for the long arm of chromosome F, and clone V1700.4, a secondary trisomic for the short arm of chromosome IX, was identified as having an extra isochromosome for the short arm of chromosome F. Chromosomes IV and IX in pachytene correspond to chromosome C and F, respectively in Giesma stained somatic cells. It was possible to locate the centromeres of the chromosomes by using pairs of secondary trisomics. The morphology of the short chromosomes is described in detail to facilitate their identification.
THE GIEMSA BANDING PATTERN OF THE AUSTRALIAN SWAMP BUFFALO (BUBALUS BUBALIS): CHROMOSOME HOMOLOGY WITH OTHER BOVIDAE
Authors: Toll G. L. , Halnan C. R. E.
Published: November 2014

A Giemsa banding method was used to obtain preparations from which a G-band idiogram for the chromosomes of the Australian Swamp Buffalo (Bubalus bubalis) was constructed. Comparison with the G-banding patterns for goat, sheep, and ox chromosomes showed a remarkably close similarity between individual pairs, banding pattern homologies for the buffalo metacentric autosomes being identifiable among the acrocentric autosomes of the other species. However, the goat and sheep lacked a comparable autosome to the buffalo 10, the buffalo lacked an autosome comparable to the ox 12, the acrocentric X chromosome of the buffalo banded most closely to the goat X and was least like the ox. The buffalo Y chromosome was unlike its counterpart in the other species. The results are in keeping with the previously expressed view of evolution within the Bovidae by a Robertsonian mechanism modified by the apparent absence of one pair of autosomes from the buffalo and of a different pair from sheep and goats.
THE EFFECT OF GENES CONTROLLING DIFFERENT DEGREES OF HOMOEOLOGOUS PAIRING ON QUADRIVALENT FREQUENCY IN INDUCED AUTOTETRAPLOID LINES OF TRITICUM LONGISSIMUM
Authors: Avivi Lydia
Published: November 2014

Different genotypes of Triticum longissimum are known to either promote or suppress chromosome pairing in crosses with polyploid wheats. Lines that promote homoeologous pairing are here designated as intermediate pairing lines, while those which have no such effect or suppress pairing are known as low pairing lines. To determine a possible effect of these genotypes on homologous pairing, tetraploidy was induced in both lines and chromosomal pairing was studied at first metaphase of meiosis. While the two induced autotetraploids did not differ in chiasma frequency or in the number of paired chromosomal arms, they differed significantly in multivalent frequency; the intermediate-pairing autotetraploid exhibited the same multivalent frequency as that expected on the basis of two telomeric initiation sites, while the low pairing autotetraploid exhibited a significantly lower frequency. It is assumed that in the autotetraploid the low pairing genotype does not affect meiotic pairing per se, but modifies the pattern of homologous association in a similar manner to that known in polyploids and caused by diploidization genes. It is speculated that the tendency for bivalent pairing in the low pairing autotetraploid is due to spatial separation of the four homologous chromosomes in somatic and premeiotic cells into two groups of two.
THE RELATIONSHIP BETWEEN THE GENOME OF TRITICUM URARTU AND THE A AND B GENOMES OF TRITICUM AESTIVUM
Authors: Dvořák Jan
Published: November 2014

Triticum urartu (2n = 14) was crossed with T. aestivum lines ditelosomic for chromosomes of the A and B genomes. Except for telosome 4Aα, the rest of the telosomes of the A genome paired in these hybrids while telosomes of the B genome did not pair. This indicates that T. urartu cannot be the donor of the B genome of 4x and 6x wheat, but carries an A genome. Compared to the rest of the hybrids, pairing of T. urartu chromosomes was significantly reduced in hybrids deficient for chromosome arms 5AS or 5BS. It is suggested that this reduction in chromosome pairing resulted from the absence of genes which promote homoelogous pairing and which are normally present on chromosome arms 5AS and 5BS in Chinese Spring.