bluuebunny/crossref_metadata_2025 huggingface dataset:
GENETIC CONTROL OF ALDEHYDE OXIDASE ACTIVITY AND CROSS-REACTING-MATERIAL INDROSOPHILA MELANOGASTER
Authors: Meidinger Eva M. , Williamson John H.
Published: November 2014

Four different genes are known to affect aldehyde oxidase activity (AO) in Drosophila melanogaster. Mutants at each of these loci eliminate AO activity and simultaneously eliminate detectable AO-crossing reacting material (AO-CRM) even though only one is the structural gene for AO (Aldoxn). The other three genes (cin1, lxd and mal) coordinately "control" the levels of activity of AO and two related enzymes, xanthine dehydrogenase (XDH) and pyridoxal oxidase (PO). Contrary to their effects on AO-CRM, neither of these three mutants eliminate XDH-CRM. A model of interaction of these enzymes and genes controlling their activities is discussed.
THE RELATION BETWEEN DISPERSAL BEHAVIOR AND REPRODUCTIVE FITNESS IN THE FLOUR BEETLE TRIBOLIUM CASTANEUM
Authors: Lavie Batia , Ritte Uzi
Published: November 2014

Assuming that dispersal from optimal environments evolved as a colonizing device, it is expected that dispersants will possess reproductive characteristics enhancing the probability of successful colonization. Two approaches were used to clarify the relationship between dispersal behavior and two major components of reproductive fitness (developmental time and fecundity) in the flour beetle Tribolium castaneum: (a) comparison between two lines, one selected for low dispersal and the other selected for high dispersal, for several components of reproductive fitness, and (b) calculation of the correlation coefficients between each fitness component investigated and dispersal behavior. The results obtained by both approaches indicate, as expected, shorter developmental time and higher fecundity for dispersants than for nondispersants.
GENOTYPE × ENVIRONMENT INTERACTIONS IN SMOOTH BROMEGRASS. II. MORPHOLOGICAL CHARACTERS AND THEIR ASSOCIATIONS WITH FORAGE YIELD
Authors: Tan Wai-Koon , Tan Geok-Yong , Walton P. D.
Published: November 2014

The parents and progenies of a 7 × 7 diallel cross of smooth bromegrass (Bromus inermis Leyss.) were evaluated for the genetic variability of some morphological characters and their associations with yield, at four locations in Alberta in 1976 and 1977. Locations, years and their interactions were highly significant for all characters and were subsequently treated as eight environments. The partition of the genotypic variance into general combining ability (GCA) and specific combining ability (SCA) showed that for all morphological characters, GCA was more important than SCA, indicating the importance of additive genetic effects. The genotype × environment (GE) interactions were highly significant. Variation accounted for by GCA was generally higher than the interaction effects of GCA and SCA with environments. Phenotypic and genotypic correlation coefficients revealed that both tiller density and height were significantly correlated with yields. Path coefficient analysis also showed that tiller density, followed by leaf area and tiller dry weight, exerted the greatest direct influence on yield. Selection for large leaf area and more and heavier tillers per unit area would simultaneously increase bromegrass productivity. Furthermore, selection should be based on multi-year and multi-location tests.
FREQUENCIES OF CENTROMERIC HETEROMORPHISMS OF HUMAN CHROMOSOMES 3 AND 4 AS DETECTED BY QFQ TECHNIQUE: CAN THEY BE IDENTIFIED BY RFA TECHNIQUE?
Authors: Verma Ram S. , Dosik Harvey
Published: November 2014

One hundred normal Caucasians were studied by sequential QFQ and RFA banding techniques in order to estimate the type and frequency of heteromorphisms in the centromeric regions of chromosome 3 and 4. Intensity variants were classified into 1 of 5 levels of QFQ banding. QFQ intensity heteromorphisms [Formula: see text] for chromosomes 3 and 4 were 62 and 15 percent respectively. The interrelationship between QFQ and RFA variants were also examined. When the centromere was brilliant by QFQ, it was found that it was deep red by RFA; when it was pale by QFQ, it was light red by RFA. Nevertheless, a blind coded study could not pick up these color variants by RFA. QFQ banding showed variations of the centromeric regions of chromosomes 3 and 4 while RFA banding failed to demonstrate it. It was concluded that QFQ is the most useful technique in detecting the different intensity levels in the centromeric regions of chromosomes 3 and 4.
CONSIDERATIONS OF A METHOD OF ANALYZING DIALLEL CROSSES OF ATLANTIC SALMON
Authors: Friars G. W. , Bailey J. K. , Saunders R. L.
Published: November 2014

Inferences derived from a proposed mixed model analysis of a diallel cross involving four stocks of Atlantic salmon (Salmo salar) are illustrated with growth data on weight and length. Variation between stocks was more apparent when samples represented dams as opposed to sires, thus stressing the relative importance of maternal effects. However, the ranking of stocks was not altered when either the means of sire sources or the means of dam sources were considered. No heterotic effects were found for the growth traits studied.
CROSS SENSITIVITY OF MUTATOR STRAINS TO PHYSICAL AND CHEMICAL MUTAGENS
Authors: Nasim A. , Brychcy T.
Published: November 2014

Ten different mutator strains of Saccharomyces cerevisiae were tested for cross sensitivity to two alkylating agents, ethylmethanesulfonate (EMS) and methylmethanesulfonate (MMS), to determine if any of them are defective in the repair systems which normally deal with damage caused by these agents. For one of the mutators, namely mut2-1, it was shown by genetic analysis that mutator activity and MMS sensitivity are both controlled by the same gene. Two mutants, mut2-1 and mut7-1, were found to be sensitive to MMS but normal to ultraviolet and γ-rays. Another group is represented by mut1, mut6 and mut8 which are not sensitive to any of the mutagens tested so far. Mutator strain mut2-1 was also shown not to be significantly altered for levels of UV-induced forward and reverse mutations. These observations lend support to the idea of multiple repair systems that deal with DNA damage caused by different agents and also show that mutator activity can often result from the loss of normal cellular repair systems.
GENETIC STUDIES ON THREE STALK TRAITS IN MAIZE USING CHROMOSOMAL INTERCHANGES
Authors: Kang M. S. , Zuber M. S. , Myers Jr. Oval , Colbert T. R.
Published: November 2014

Yield losses due to stalk-lodging in maize (Zea mays L.) have been estimated at 5 to 25% annually. Information on chromosomal arms carrying gene(s) favorable to stalk-quality improvement would be useful to maize breeders. Reciprocal chromosomal translocations (interchanges) were used to locate genes for three stalk-quality traits, viz, stalk-section weight, crushing strength, and rind thickness, in two inbred lines (B14A and B37) with excellent stalk-quality, using two testers (Oh43 and N31) with poor stalk-quality. Genes conditioning stalk-section weight were located in nearly all the ten linkage groups. Six and seven chromosome arms were found to carry gene(s) for stalk crushing strength in B14A and B37, respectively. Rind thickness was found to be controlled by four chromosome arms in B37 and possibly by two arms in B14A. This information may be helpful to maize breeders in improving stalk-quality in maize by transferring favorable chromosome arms by means of chromosomal interchanges. Certain chromosome arms could not be conclusively ruled out. Additional translocations involving each of the following chromosome arms should be studied for this purpose: 1L, 3L, 5S, 6S, 8S, 10S, and 10L. The shriveled (semi-sterile) versus non shriveled (fertile) anther classification method could be reliably used to determine semi-sterility and fertility in a normal growing season.
EBONY, A SEMIDOMINANT LETHAL MUTANT IN THE MOSQUITO ANOPHELES ALBIMANUS
Authors: Benedict M. Q. , Seawright J. A. , Anthony D. W. , Avery S. W.
Published: November 2014

Ebony (eb), a semidominant, autosomal mutant, was discovered in a stock of Anopheles albimanus Wiedemann that was treated with ethyl methane sulfonate. Ebony homozygotes are uniformly black during the four larval instars and die most commonly during the transition to the pupal stage. The heterozygotes (eb/eb+) are intermediate in color and fully viable. Propoxur resistance (prr) and the T(Y;2R)1 translocation were employed in crosses to assign eb to the left arm of chromosome 2.
CYTOLOGY OF A GENETIC SEXING SYSTEM IN ANOPHELES ALBIMANUS
Authors: Kaiser P. E. , Seawright J. A. , Joslyn D. J.
Published: November 2014

Several translocation and translocation-inversion strains were induced in Anopheles albimanus Wiedemann by using X and gamma irradiation. The propoxur resistance allele (prr), located on chromosome arm 2R, was used to screen for T(Y;2R) translocations and In(2R) inversions. Six T(Y;2R) translocations and eight In(2R) inversions are described herein. The strains designated In(2R)[T(Y:2R)3]2 and In(2R)[T(Y;2R)6]4 eliminated 99.8% and 99.7%, respectvely, of the crossing over between the translocation breakpoint and the prr locus. A direct correlation is shown between genetic map units and physical distance (micrometers) of the polytene chromosome. Inversions are shown to eliminate recombinants in excess of the expected value based on physical size of the aberration. The Y chromosome, which is heterochromatic and located in the chromocenter in polytene complements, is visible in two terminal translocations.
LETHAL ZYGOSIS IN RECOMBINATION–DEFICIENT MUTANTS OFESCHERICHIA COLI
Authors: Nestmann Earle R.
Published: November 2014

Use of nonselective medium for plating cells following mating has revealed that Rec−recipient strains of E. coli may be killed as a result of conjugation. Sensitivity of RecA−, RecB−, and RecC−recipients increases with ratio of donor: recipient cells in mating mixtures and with time of mating. A Rec+recipient shows no lethal zygosis in these experiments performed without aeration. Cell contact does not seem to be responsible for the sensitivity of Rec−strains, since lethality is prevented when cell contact is permitted but DNA transfer is not. Thus, an event(s) occurring subsequent to entry of donor DNA appears to cause lethality in Rec−recipients.
THE MUTAGENIC ACTIVITY OF 61 AGENTS AS DETERMINED BY THE MICRONUCLEUS, SALMONELLA, AND SPERM ABNORMALITY ASSAYS
Authors: Bruce W. Robert , Heddle John A.
Published: November 2014

A comparison of two rapid and inexpensive in vivo mammalian assays and the Ames Salmonella assay is presented for 61 agents; Acetylsalicylic acid; Acriflavine; Actinomycin D; 2(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2); Aflatoxin B1; 2-aminofluorene; Aminopterin; Aroclor 1254; Ascorbic acid; Azathioprine; Benzo(a)pyrene; 5-Bromo-2'-deoxyuridine; Busulphan; Butylated hydroxytoluene; Cadmium chloride; Caffeine; Calcium cyclamate; Chloral hydrate; Chloromycetin succinate; Codeine phosphate; Colchicine; Cycloheximide; Cyclophosphamide; DDT; 2,4-Diaminoanisole; Dibutylnitrosamine; 9,10 Dimethyl-1,2-benzanthracene; 1,1 Dimethylhydrazine; Dimethylnitrosamine; Epinephrine; Ethyl methane sulphonate (EMS); 2-formylamino-4-(5-nitro-2-furyl)thiazole (FANFT); 2-(2-formylhydrazino)-4-(5-nitro-2-furyl)thiazole (FNT); Glucose; Griseofulvin; Hycanthone methane sulphonate; Hydroxyurea; 5-Iodo-2'-deoxyuridine; Lead acetate; Mechlorethamine; 3-Methylcholanthrene; Methyl mercury acetate; Methyl methane sulfonate (MMS); N-methyl-N-nitro-N'-nitrosoguanidine; Mitomycin C; Monosodium glutamate; 1-Naphthalamine; 2-Naphthalamine; Nitrofurazone; 4-Nitro-O-phenylene diamine; 4-Nitro-quinoline-1-oxide (4-NQO); Phenobarbitone; Procarbazine; Quinacrine dihydrochloride; Radiation (γ-rays); Sodium chloride; Triethylene thiophosphoramide; Trimethyl phosphate; Tris(2-methyl-1-arizidinyl) phosphine oxide; Urethan; Vinblastine. The results support the concept of multiple assays for mutagenicity and show that some combinations of assays are superior to others.
GENOMES OF THE AUSTRALIAN WILD SPECIES OF COTTON. II. THE DESIGNATION OF A NEW G GENOME FORGOSSYPIUM BICKII
Authors: Edwards G. Allan , Mirza M. Anwar
Published: November 2014

Gossypium bickii Prokh. is distinct from the C genome species, although it was tentatively placed in this genome. A comparison of the karyotypes of G. bickii and G. sturtianum Willis separates G. bickii sharply from G. sturtianum, the standard species for the C genome. Karyotypic differences are evident in centromere position of the chromosomes, chromosome size, and the lack of satellites or secondary constrictions in G. bickii. A clear separation of G. bickii from G. sturtianum and other Gossypium species is also demonstrated in previous studies of phenetic analysis, flower flavonoids, DNA content, and electrophoresis of seed proteins, esterases, leucine aminopeptidases, and catalases. G. bickii is placed in a new G genome and is assigned to the 2G1subgenome.
THE CONTROL OF ALDEHYDE OXIDASE AND XANTHINE DEHYDROGENASE ACTIVITIES BY THE CINNAMON GENE IN DROSOPHILA MELANOGASTER
Authors: Bentley Michael M. , Williamson John H.
Published: November 2014

The isolation and characterization of 16 alleles of the cinnamon (cin, 1-0.0) locus in Drosophila melanogaster are described. The effects of cin on viability and the maternal effect of cin+ on eye color have been separated from each other as well as from the deficiency for aldehyde oxidase (AO) and xanthine dehydrogenase (XDH) activities. These 16 alleles have been assigned to four complementation groups based on analysis of AO and XDH activities in all heteroallelic female combinations. Zygotic complementation for lethality and eye color has been characterized and allows the ordering of cin alleles in a consistent pattern for the ability to produce viable zygotes and/or complement for the eye color phene. Several complementing cin combinations were analyzed for heat stability of AO. In all cases, AO from allelic heterozygotes was more heat labile than wild-type AO. One cin allele, cin13, produces heat labile AO in combination with cin+ from Oregon-R, hence exhibiting a "dominant" heat stability phenotype.
STERILITY IN SUCCESSIVE BACKCROSSES OFRAPHANOBRASSICA(2n = 4x = 36) WITH RECURRENTBRASSICA OLERACEA(2n = 2x = 18)
Authors: McCollum Gilbert D.
Published: November 2014

A series of crosses to develop cytoplasmic male sterility in the cole crops by transferring the Brassica oleracea L. (2n = 18) genome into the cytoplasm of radish (Raphanus sativus L., 2n = 18) through the amphidiploid Raphanobrassica (2n = 4x = 36) was terminated because of complete seed sterility of the only two BC6hybrid plants obtained. There was no improvement of seed set in six backcrosses to diploid B. oleracea, and the chromosome numbers of the few plants producing seeds were higher than expected, frequently being close to the triploid number (2n = 3x = 27) of the BC1. Zygotes with less than two radish chromosomes were not found; those with less than four were few; and those with less than six rarely produced offspring.
DNA-MEDIATED CORRECTION OF ARABIDOPSIS THIAMINE MUTANTS. I. DESCRIPTION OF CORRECTED MUTANTS
Authors: Ledoux L. , Huart R. , Ryngaert-Adriaensens A. , Matagne R. F. , Schlösser J. P. , Jacobs M.
Published: November 2014

Fourteen corrected strains previously obtained by treating three thiamine mutants of Arabidopsis thaliana (L.) Heynh. with bacterial DNA were analysed for phenotypic expression in various culture conditions and for genetic behavior in outcrosses. Three classes of plants could be recognized: 1) variegated strains phenotypically similar to viable mutants at the th-2 locus, 2) plants green at 22 °C but showing abnormal phenotypes (reversible by thiamine treatment) when grown at lower temperature (16 °C) in the presence of glucose, 3) green plants insensitive to temperature and glucose. Plants of the first class were compared to two th-2 mutants from which they differed in response to various metabolites, and, most strikingly, to a mixture of thiazole and pyrimidine. From crosses between variegated corrected plants and th-2 mutants, variegated F1 progenies were obtained, suggesting allelism. However, control crosses between th-2 and tz or py mutants indicated incomplete complementation, making conclusions from allelism tests using these strains difficult. Further study of F2 segregants pointed out the difficulty in using variegation as a reliable marker. Crosses with two strains (of classes 1 and 3) showed the absence of correcting suppressor-like genes unlinked to the original mutation. Finally, a new set of DNA corrected plants obtained from other thiamine mutant strains bearing several genetic markers confirmed the reality of the correction and will facilitate its mapping.
INHERITANCE OF RESISTANCE TO THE TOBACCO VEIN-MOTTLING VIRUS IN TOBACCO
Authors: Legg Paul D. , Litton C. C. , Collins G. B.
Published: November 2014

The Virgin A Mutant was resistant to the tobacco vein-mottling virus. Resistance was controlled by a single genetic factor and was recessive in the sense that a homozygous genotype was necessary to obtain plants completely free of symptoms. Rating of infected plants indicated that the heterozygote was intermediate and the gene action was completely additive. In a second study, differences among burley cultivars for tolerance to TVMV were influenced by both additive and nonadditive genetic factors.
INHERITANCE OF CROWN RUST RESISTANCE IN THREE ACCESSIONS OF AVENA STERILIS
Authors: Harder D. E. , McKenzie R. I. H. , Martens J. W.
Published: November 2014

The inheritance of resistance to oat crown rust was studied in three accessions of Avena sterilis L. Accession CAV 4274 originated from Morocco, CAV 4540 from Algeria, and CAV 3695 from Tunisia. Seedling rust tests on F2 backcross families indicated the presence of two dominant genes for crown rust resistance in CAV 4274. One of these, a gene conditioning resistance to most races tested, was linked or allelic to gene Pc-38, and was designated gene Pc-62. The second gene conferred resistance only to one of the six races studied, and was not tested further. In CAV 4540, a single dominant gene, Pc-63 was possibly allelic with Pc-62 and linked or allelic to Pc-38. Genes Pc-62 and 63 are generally similar to Pc-38 in their resistance spectrum, but these three genes are differentiated by races CR 102, CR 103, and CR 107. A single dominant gene in CAV 3695 appeared to be Pc-50.
DNA REASSOCIATION KINETICS OF FOUR CONIFERS
Authors: Rake Adrian V. , Miksche Jerome P. , Hall Richard B. , Hansen Kenneth M.
Published: November 2014

The DNA genome size of four conifers was determined cytophotometrically and the diploid amounts of DNA per cell of Picea glauca (Moench)Voss, Pinus banksiana Lamb., Pinus lambertiana Dougl., and Pinus resinosa Ait. were 19.3, 29.8, 87.7 and 43.1 pg., respectively. These DNA values yield rRNA gene numbers considerably lower than previously published (Hotta and Miksche, 1974). The DNA was further characterized by studying the kinetics of reassociation. The results indicated that in all four conifers there are four repeated nucleotide sequence fractions and one unique fraction. The genome size as determined by reassociation of the single copy DNA approximated the genome size determined by cytophotometry for Picea glauca and Pinus banksiana. Pinus lambertiana and Pinus resinosa appeared to have a genome size, as determined by cytophotometry, larger than the genome sizes determined by reassociation, indicating possible ploidy of their respective genomes.
CHROMOSOME ANALYSIS OF SCHISTOSOMA RODHAINI (TREMATODA: SCHISTOSOMATIDAE)
Authors: Atkinson Kristine H.
Published: November 2014

The chromosome number of Schistosoma rodhaini Brumpt is 2n = 16, with apparent sexual dimorphism quantifiable in chromosome pair no. 2. A method for dissociating host tissue coupled with hypotonic treatment yields permanent mitotic chromosome spreads with very defined centromere regions. The karyotype of S. rodhaini is very similar to that of its sibling species, S. mansoni Sambon, except there is a pericentric inversion in the S. rodhaini nucleolar organizer chromosome pair, S. rodhaini does not have any satellited chromosomes, and S. rodhaini has slightly shorter short arms of the group I chromosomes than S. mansoni. This distinction of chromosomes of similar species of schistosomes will be important for field identification of parasites and in elucidating the evolution of the schistosomes.
LM, TEM AND SEM OBSERVATIONS OF ANTHER DEVELOPMENT IN THE GENIC MALE-STERILE (ms9) MUTANT OF CORNZEA MAYS
Authors: Greyson R. I. , Walden D. B. , Cheng P. C.
Published: November 2014

The cytological development of the anther of the genic male-sterile ms 9/ms 9 of Zea mays L. was studied with the light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Anther development in this mutant is indistinguishable from that in normal fertile material until the late Pre-Callose (Stage IIb) condition. At this stage, both at the LM level and in TEM views, the cytolysomes of PMCs and tapetum reveal densely staining bodies (DSBs) which frequently appear to surround portions of cytoplasm. These DSBs are double membrane bounded and frequently associated with ER. PMC degeneration begins prior to meiosis though tapetal cells remain intact until the equivalent of the Near Mature Pollen Stage (VIII). Tapetal cells of ms 9/ms 9 material, following mitosis, frequently develop thin walls between the two nuclei. We conclude that the DSBs represent a class of lysosome called autophagic vacuoles or cytolosomes. It is not clear whether they are elaborated directly in response to the mutant allele or perhaps represent a cytological response to genetically based abnormal biochemistry. Despite the early failure of PMCs and tapetal cells, epidermal cells of ms 9/ms 9 anthers develop cuticular ridges quite similar to those formed on normal fertile anthers.
LINKAGE RELATION OF RESISTANCE TO CLADOSPORIUM LEAF MOLD (Cf-2) AND ROOT-KNOT NEMATODES (Mi) IN TOMATO AND A NEW GENE FOR LEAF MOLD RESISTANCE (Cf-11)
Authors: Kerr E. A. , Kerr Elizabeth , Patrick Z. A. , Potter J. W.
Published: November 2014

Mi derived from Anahu and Cf-2 derived from Indian River are approximately at locations 35 and 43 on the long arm of chromosome 6 of the tomato (Lycopersicon esculentum Mill.). Ontario 7716 contains the leaf mold resistance gene Cf-11 which was derived from an aberrant plant of Mass. #2. Both Cf-2 and Cf-11 confer immunity from Cladosporium fulvum Cke. races 1 and 10. Cf-11 confers high resistance to race 6 and slight tolerance to race 12 whereas Cf-2 does not confer any resistance to these races of C. fulvum.
CHROMOSOME RELATIONSHIPS AND MORPHOLOGICAL COMPARISONS BETWEEN THE DIPLOID OATS AVENA PROSTRATA, A. CANARIENSIS AND THE TETRAPLOID A. MAROCCANA
Authors: Leggett J. M.
Published: November 2014

The morphology and chromosome pairing of the triploid hybrids Avena canariensis Baum, Rajhathy et Sampson × A. maroccana Gdgr., A. prostrata Ladiz × A. maroccana, the diploid A. prostrata and the tetraploid derived between A. prostrata and A. canariensis and the tetraploid hybrid between this derived tetraploid and A. maroccana are described in relation to genomic affinities between these species. The cytological evidence is at variance with morphological and geographical data which initially indicated that A. canariensis was the donor of the A genome of the A. maroccana-A. murphyi group of tetraploids. The possible relationship between the species is briefly discussed.
STUDIES ON THE X-CHROMOSOME OF THE NEMATODEPANAGRELLUS REDIVIVUS: EMS INDUCED VISIBLE MUTATIONS
Authors: Burke D. J. , Samoiloff M. R.
Published: November 2014

Young virgin males and females of the free-living nematode Panagrellus redivivus (deMan 1913) Goodey 1945 were mutagenized with 0.05 M ethyl methanesulphonate for 4 h. Twenty-four X-linked mutants were isolated, but only eight could be maintained as homozygotes due to severity of phenotype and mating inefficiency. The mutants define six complementation groups. The mutation frequency per locus was estimated to be 4.4 × 10−4following EMS treatment. An estimated 330 essential loci occur on the X-chromosome of P. redivivus.
DETERMINATION OF CELL CYCLE IN PLANTS USING BrdU-FPG
Authors: Evans Kirby J. , Filion W. Gary
Published: November 2014

The BrdU-FPG method for differential staining of sister chromatids was employed to estimate the cell cycle time in two plants species. The protocol is based upon the ability to differentiate cytologically between chromosomes which have completed two or three DNA synthesis phases. Vicia faba L. which has a well established cell cycle time was used to verify the technique. Utilizing this method the cell cycle time of Zebrina pendula Schnizl. root tip meristem cells was determined to be 17.0 hours.
CYCLOHEXIMIDE-INDUCED NUCLEAR ALTERATIONS IN MAIZE ROOT TIPS
Authors: Baszczynski C. L. , Walden D. B. , Atkinson B. G.
Published: November 2014

Cycloheximide appears to act in G2and also at the end of metaphase in disrupting the normal progression of chromosomes through the nuclear cycle in Zea mays L. A dose of 7.5 µg/ml resulted in the accumulation of metaphase figures at 60 min. Regardless of the length of treatment (60 or 120 min), a drop in mitotic index occurred after 60 min due to a decrease in the frequency of prophases. This reduction is attributed to a cycloheximide-sensitive transition point in G2approximately 1 to 1.5 h before the start of mitosis. The incorporation of14C-leucine into proteins was found to be inhibited by cycloheximide at concentrations ranging from 0.75 µg/ml (very slight inhibition) to 750 µg/ml (almost complete inhibition). Label incorporation into those proteins found in the nuclear fraction was inhibited sooner and to a lesser extent than into total proteins. Cycloheximide at 75.0 µg/ml induces a variety of cytogenetic variants of which nine classes were observed. These included alterations in both chromosome morphology and nuclear organization and occurred at frequencies significantly higher than the controls. The results suggest that cycloheximide can act at several levels of organization which together are essential for establishing and maintaining the events of the nuclear cycle.
OUTCROSSING RATES IN BARLEY POPULATIONS IN THE CANADIAN PRAIRIES
Authors: Chaudhary H. R. , Jana S. , Acharya S. N.
Published: November 2014

Using three morphological markers, the magnitude of natural cross-fertilization in three successive generations, F3, F4and F5of four single crosses of barley (Hordeum vulgare L.) was estimated under dryland conditions of the Canadian Prairies. The average frequency of outcrossing was very low (0.35%). Somewhat higher rates of outcrossing were observed in a highly variable composite cross population of barley (CC XXI). CC XXI showed an overall outcrossing rate of 0.80%, when propagated under irrigated conditions, but only 0.47% under rainfed conditions. Outcrossing was significantly influenced by three components of the environment: temperature, precipitation and relative humidity during the flowering period. Temperature was most important when moisture was not limiting, whereas precipitation was the most important factor under field level drought. The overall frequency of outcrossing in CC XXI was not only considerably lower in the Prairies than in California or Scotland, but decreased progressively with advancing generations, in contrast to results in California.
COMPARATIVE KARYOLOGY OF THE FRESHWATER SNAILS BULINUS TROPICUS and B. NATALENSIS
Authors: Goldman Michael A. , LoVerde Philip T. , Chrisman Charles L.
Published: November 2014

Species of the subgenus Bulinus s.s. occur in a polyploid series which is of interest because of the rarity of polyploidy in animal species and because there appears to be a relation between ploidy level and ability to transmit Schistosoma haematobium, a parasite of major public health importance. We describe a technique for the preparation of standard karyotypes using cell suspensions from colchicine-treated embryos. The results for two diploid species, B. tropicus (Krauss) and B. natalensis (Küster), are presented. Both karyotypes consist of 15 metacentric and 3 submetacentric chromosomes. However, differences in centromere position are found in four pairs of chromosomes, and in the appearance of a secondary constriction. Because B. natalensis may represent a relict taxon involved in the origin of the polyploids, the results are of significance for future work on the phylogeny of this group.
BIVALENT FORMING RACE OFMESOCYCLOPS EDAX(COPEPODA, CRUSTACEA)
Authors: Chinnappa C. C.
Published: November 2014

Meiosis and chromosome morphology in females of a bivalent forming race of Mesocyclops edax (S. A. Forbes) are described. Meiosis is achiasmate and exhibits regular bivalent formation (2n = 14). Chromosome analyses of other populations of M. edax revealed that the females are heterozygous for several interchanges leading to the formation of large rings. Chromatin diminution during cleavage stages suggests that the elimination of H-segments occurs at the fourth cleavage division.
INHERITANCE OF REDUCED-EYE IN THE GRASSHOPPER MELANOPLUS SANGUINIPES
Authors: Chapco W.
Published: November 2014

The inheritance of an eye abnormality, reduced-eye, is described in the migratory grasshopper Melanoplus sanguinipes (Fabricius). Phenotypically, the compound eyes are flat and narrow and greatly reduced in size. Facets are absent. Pleiotropic effects include a crease in the vertex of the head, the absence of ocelli and low viability. Data from crosses suggest that reduced-eye is monogenically controlled and is due to an autosomal recessive.
INVITATIONAL PAPER: SOMATIC CELL GENETICS: A REVIEW OF DRUG RESISTANCE, LECTIN RESISTANCE AND GENE TRANSFER IN MAMMALIAN CELLS IN CULTURE
Authors: Wright Jim A. , Lewis William H. , Parfett Craig L. J.
Published: November 2014

During the past decade development of selection procedures for isolating a large variety of altered stable phenotypes in mammalian cell culture has been extremely rapid. The list now includes temperature sensitive, auxotrophic, drug resistant and lectin resistant cell lines, as well as cultures containing altered products of differentiation. As a general class, the drug resistant mutants have been studied more often than any of the others because of the wide variety of very interesting and specifically altered mutants that can be isolated, and the ease with which they can usually be obtained. In this review we discuss the essential features of the best studied drug and lectin resistant systems. Also a section on gene transfer has been included since the new technology being developed in this area is certain to have great influence on our understanding of fundamental aspects of somatic cell variation.
ISOLATION AND GENETIC ANALYSIS OF MMS-SENSITIVEMUSMUTANTS OFNEUROSPORA
Authors: Käfer E. , Perlmutter E.
Published: November 2014

With the aim of obtaining mutants that affect DNA repair or recombination, mutants sensitive to methylmethane sulfonate (MMS) have been isolated in the ascomycete Neurospora crassa. Seven of these mutants were backcrossed repeatedly to produce isogenic strains for measurements of relative mutagen sensitivities and for analysis of recombination frequencies. The new mus (mutagen sensitives) were compared to four previously known radiation-sensitive mutants which were shown to be cross-sensitive to MMS. Tests for allelism assigned the mus mutants to five new genes, mus-7 to mus-11, each mapping in a different linkage group. In homozygous crosses all mutants were sterile, except the two alleles of gene mus-10 which occasionally produced some viable ascospores. Complementation tests on MMS-media identified double mutant strains from many intercrosses. Such strains can be used for analysis of interactions between mutant alleles from different genes and of possible epistatic groupings for repair-deficient mutants in Neurospora. Four of these double mutant strains, all containing mus-8 and previously known mutants, were checked for survival on MMS media and their sensitivities were compared to those of their parental single mutant strains. Results indicate that mus-8 may be epistatic to uvs-2 which is deficient in excision repair, but not to mutants like uvs-3 that appear to be deficient in error-prone repair.
MICROCHROMOSOMES OF THE ONTARIO RED FOX (VULPES VULPES): AN ATTEMPT AT CHARACTERIZATION
Authors: Ellenton J. A. , Basrur P. K.
Published: November 2014

Characterization of the microchromosomes of the red fox, Vulpes vulpes Linn., was attempted through the examination of mitotic chromosomes using Giemsa banding, quinacrine banding, the silver nitrate-ammoniacal silver technique for staining nucleolar organizers, and autoradiographic procedures. Pachytene cells were examined in air-dried and squash meiotic preparations and in testicular tissue sectioned for light and electron microscopy. The results of banding procedures on mitotic chromosomes and the staining properties of the microchromosomes at pachytene indicated that the microchromosomes likely contain both heterochromatin and euchromatin. Autoradiographic analysis showed that the microchromosomes replicate during mid S phase while the Y chromosome, which is in the size range of the microchromosomes, replicates during late S phase. From these observations, it would appear that the microchromosomes may not be exclusively heterochromatic as hypothesized previously. With the use of the silver nitrate-ammoniacal silver technique, the presence of nucleolar regions were detected on specific macrochromosomes but not on any of the microchromosomes. Examination of pachytene chromosomes in air-dried and squash preparations, and of testicular tissue sectioned for light and electron microscopy, also indicated that the microchromosomes may not be involved in the organization of the nucleolus in the red fox.
DIPLOID, ANEUPLOID AND TRIPLOID PLANTS FROM HAPLOID × DIPLOID CROSSES IN FLAX (LINUM USITATISSIMUM)
Authors: Murray Beatrice E.
Published: November 2014

Flax (Linum usitatissimum L.) haploids (2n = x = 15), selected from haploid-diploid twin seedlings in the cultivar Rocket 4 and crossed with diploid sibs, differed in boll-set; in frequency of diploid, aneuploid and triploid plants in each F1 family (58, 20 and 22%, respectively); and in frequency of twins in F2 families. The diploid plants of the F1 progeny were fertile and high in seed yield which contrasted with the sterility of the triploids and low fertility, or sterility, of the aneuploids. Twinning frequency and boll-set was stabilized at specific levels in some doubled haploid lines. The advantages of haploid × diploid crosses for genetic experimentation are discussed.
SILVER STAINED CORE-LIKE STRUCTURES IN CHINESE HAMSTER METAPHASE CHROMOSOMES
Authors: Kaiserman Morton Z. , Burkholder Gary D.
Published: November 2014

Chinese hamster metaphase chromosomes, subjected to prolonged hypotonic pretreatment and subsequently stained with ammoniacal silver, contained a darkly-stained core-like structure in each chromatid, surrounded by a halo of dispersed chromatin which was pale yellow to brown in color. The core was variable in its appearance, ranging from a continuous linear configuration to a spiralized structure or a discontinuous, particulate structure. Within the centromeric regions, the cores frequently appeared more intensely stained than elsewhere in the chromosome. The nucleolus organizers also stained darkly and appeared to be attached to the core-like structures. It remains to be determined whether the cores represent a real component of metaphase chromosome structure, or whether they are artifacts resulting from abnormal chromatin aggregation arising at the time of chromosome preparation.
MULTIPLE ALLELISM AT THEMATB LOCUS INPHYSARUM POLYCEPHALUM
Authors: Kirouac-Brunet Josée , Masson Sylvie , Pallotta Dominick
Published: November 2014

Each of the natural plasmodial isolates of Physarum polycephalum studied contains two different alleles for the matB and the matA loci. This result is further evidence for the presence of a two-locus system for limiting inbreeding in nature. Only amoebae carrying different matB alleles will fuse efficiently and only those diploid amoebae heterozygous for the matA locus will differentiate with a high frequency. Both the matA and matB loci are multiallelic. In this work ten new mat B alleles were found, bringing to 13 the number of known alleles; there are a minimum of 13 alleles at the matA locus (Collins and Tang, 1977). The presence of a large number of alleles at each of these loci increases the probability that in nature amoebae from different plasmodia are sexually compatible.
THE INTERACTION OF GENETICALLY CONTROLLED CROSSABILITY IN WHEAT AND RYE
Authors: Tanner D. G. , Falk D. E.
Published: November 2014

A random sample of nine inbred (S8) rye lines (Secale cereale L.) exhibited significant differences in crossability with several wheat (Triticum aestivum L.) lines. Results obtained from crosses among selected wheat and rye lines indicate that the crossability system in rye may interact with the Kr loci controlling intergeneric crossability in wheat. Certain rye lines are capable of partially circumventing one or both of the known crossability inhibitor genes in homozygous wheat lines. Crossability in rye appears to be simply inherited with high crossability being dominant.
CENTROMERIC BANDING IN MAIZE
Authors: Chow C. , Larter E. N.
Published: November 2014

A modified Leishman C-banding technique is described which can produce a complete set of centromeric bands on the somatic metaphase chromosomes of maize (Zea mays L.). Several interstitial (minor) C-bands, additional to those revealed by the conventional C-banding method, were observed. Centromeric bands were produced only after both an alkali and salt treatment were incorporated into the treatment schedule and a subsequent water rinse was omitted. Apparently, the combined action of alkali and salt treatments provided a positive contribution to the centromeric regions which otherwise remained unstained using the standard C-banding technique.
EFFECT OF THE SINGED LOCUS ON THE EGG PRODUCTION CURVE OFDROSOPHILA MELANOGASTER
Authors: Alvarez Gonzalo , Fontdevila Antonio
Published: November 2014

Egg production curves of virgin and mated females of several genotypes at the singed locus of Drosophila melanogaster have been studied. Fitz-Earle's theoretical model (1971) for characterizing daily egg production has been used. In general, the model gave good fit to the experimental data. A clear effect of the female genotype is detected on the following parameters and derivations of the model: α, rate of decrease in egg production; tq, day of cessation of egg-laying, N(tmax), maximum egg production; and T(to,tq), total lifetime egg production. Homozygous snqrfemales present higher values of α and lower values of tq, N(tmax), and T(to,tq) than heterozygous and wild-type homozygous females. Egg-to-larva viability along female lifetime related with the different physiological stages of the egg-laying curve (increasing, maximum, and decreasing parts) has been also studied. Homozygous snqrfemales show low viability and decreasing with age compared to wild-type females. In some cases, different physiological stages of the egg production curve show characteristic egg-to-larva viability values.
DIFFERENTIAL FERTILITY AND TRANSMISSION OF MALE AND FEMALE GAMETES IN ALLOPLASMIC WHEAT HYBRIDS
Authors: Tsuji Seiichi , Maan S. S.
Published: November 2014

Alloplasmic Triticum aestivum L. cv. Selkirk lines having cytoplasms of five D-genome Aegilops species were crossed reciprocally with euplasmic T. durum Selection 56-1 to study differential cytoplasmic effects on pentaploid hybrids. Pollen fertility of the alloplasmic and euplasmic pentaploid hybrids ranged from 23.0% to 46.6%, and from 84.9% to 91.1%, respectively. Significant differences in seed-set and in the viability of backcrossed seed were observed between the euplasmic and alloplasmic pentaploids as well as among the five alloplasmic pentaploids. The pentaploid with Ae. squarrosa cytoplasm did not transmit 14-chromosome male gametes. The cytoplasms of Ae. squarrosa, Ae. cylindrica and Ae. ventricosa were similar to one another in their differential effects on the transmission of euploid and aneuploid male gametes numbers, and similarly the cytoplasms of Ae. crassa and Ae. juvenalis resembled each other.
GENOME RELATIONSHIPS AMONGELYTRIGIA(=AGROPYRON)ELONGATA,E.STIPIFOLIA, "E.ELONGATA4x,"E.CAESPITOSA,E.INTERMEDIA, AND "E.ELONGATA10x"
Authors: Dvořák J.
Published: November 2014

Hybrids were obtained from the crosses Elytrigia elongata (Host) Holub × "E. elongata 4x", E. stipifolia Czern. ex Nevski × "E. elongata 4x," "E. elongata 4x" × E. caespitosa (C. Koch) Nevski, and E. intermedia (Host) Nevski × E. caespitosa. "Elytrigia elongata 10x" was crossed with four ditelosomic additions of E. elongata telosomes to Triticum aestivum L. em. Thell. Elytrigia intermedia was crossed with ditelosomic addition of "E. elongata 10x" telosome 7e11α to T. aestivum. The S genome of E. stipifolia appears to be related only very remotely to the E genome of E. elongata. "Elytrigia elongata 4x" has two modified E genomes, which are designated Esand Esc. The genomes of E. caespitosa, tentatively designated X15and X15c, are related to each other; both are considered to be distantly related to the E genome. Elytrigia intermedia has two genomes, designated N and N1, that are distantly related to the E genome and one genome of an unknown origin tentatively designated X4. It is suggested that "E. elongata 10x" has at least two genomes that are related to the E. genome.
SELECTION FOR SERUM CHOLESTEROL, VOLUNTARY PHYSICAL ACTIVITY, 56-DAY BODY WEIGHT AND FEED INTAKE IN RANDOMBRED MICE. II. CORRELATED RESPONSES
Authors: Dunnington E. A. , White J. M. , Vinson W. E.
Published: November 2014

Randomly bred ICR mice were selected for five generations for high and low serum cholesterol (SC), voluntary physical activity, 56-day body weight and feed intake. An unselected, randomly bred control line was maintained with each pair of selection lines. Significant increases in mature body weight occurred in males of high weight and high intake lines and in females of high SC, high weight and high intake lines. Significant decreases in mature body weights occurred in males of low weight line and in females of low SC and low weight lines. Both high and low selected SC lines had greater (P<0.05) activity scores and consumed more feed than the SC control. Mice selected for high activity consumed more (P<0.05) feed than mice selected for low activity. Mice selected for high 56-day body weight consumed more (P<0.05) feed and had higher SC than mice selected for low 56-day body weight. Mice selected for high feed intake were heavier (P<0.05) and more active (P<0.05) than low feed intake mice but had significantly lower SC levels.
VARIANCE COMPONENT ESTIMATION AND PREDICTION OF BREEDING VALUES
Authors: Kennedy B. W.
Published: November 2014

A brief review is given of prediction of breeding values when the genetic and phenotypic variances of the trait are known. In many situations, however, these variances are not known and must be estimated from the data. A review is given of the traditionally used analysis of variance (ANOVA) type methods of variance component estimation and of the more recently developed methods of maximum likelihood (ML), restricted maximum likelihood (REML), minimum norm quadratic unbiased estimation (MINQUE) and some variations on MINQUE. Criteria for choosing among methods are discussed and the consequences of applying estimates obtained by these methods in place of known variances to the prediction of breeding values are considered. The methods are illustrated for estimation of paternal half-sib heritability and prediction of breeding values of sires using a small numerical example. Lastly, the consequences of selection on prediction of breeding values and estimation of components of variance for populations under selection are discussed.
EVIDENCE FOR COMPLEMENTARY GENE ACTION CONFERRING RESISTANCE TO PUCCINIA GRAMINIS AVENAE IN AVENA SATIVA
Authors: Martens J. W. , Rothman P. G. , McKenzie R. I. H. , Brown P. D.
Published: November 2014

Plants derived from a cross between the oat cultivar Kyto (Avena sativa L.) and A. sterilis L. were highly resistant to oat stem rust (Puccinia graminis Pers.) in the adult plant stage. This resistance was much superior to that of either parent. This is the first example of transgressive segregation in this host-parasite system. The genetic mechanism of this resistance is not completely understood but the resistance appears to be conferred by gene Pg-12 from Kyto interacting with a second gene. An alternate hypothesis is that a suppressor gene in Kyto prevents the resistance conditioned by Pg-12 from being expressed in the adult plant stage. This type of resistance is highly effective against all but two of the oat stem rust races known to occur in North America.
THE TRANSFER OF GENE SR6 FROM CHROMOSOME 2D TO AN A OR B GENOME CHROMOSOME IN WHEAT (TRITICUM AESTIVUM)
Authors: Knott D. R.
Published: November 2014

A procedure was carried out to transfer to an A or B chromosome of wheat (Triticum aestivum L.), a segment of chromosome 2D carrying the gene Sr6 for resistance to stem rust (Puccinia graminis tritici Eriks. and Henn.). The objectives were to make Sr6 available for breeding in durum wheat (Triticum turgidum L.) and to study dosage effects with Sr6. Plants were produced that had 14 pairs of chromosomes (the A and B genomes) plus an added chromosome 2D carrying Sr6, either as a whole chromosome or as an isosome or telosome. Seeds from these plants were irradiated with thermal neutrons and the M1 progeny were used as male parents in crosses with the durum cultivar Kubanka. Progeny that carried Sr6 and were resistant to stem rust were examined cytologically for the presence of translocations. Five translocations were obtained and then transferred to the hexaploid level by backcrossing. Homozygous lines were produced and four were analyzed in crosses with the Chinese Spring monosomics. In two of them the segment of the A or B genome chromosome had apparently been lost as a result of crossing over. In a third line the translocation involved 2D and its homoeologue 2A. In the final line it appeared that a segment of 2D had been inserted into chromosome 7B. When the chromosome carrying this translocation was transferred to the hexaploid level a position effect occurred that affected the expression of Sr6.
REACTION OF WHEAT TO COMMON ROOT ROT: LINKAGE OF A MAJOR GENE, Crr, WITH THE CENTROMERE OF CHROMOSOME 5B
Authors: Larson Ruby I. , Atkinson T. G.
Published: November 2014

'Cadet' (C), a cultivar of Triticum aestivum L., carries the major recessive gene, Crr, for moderate resistance to common root incited by Cochliobolus sativus (Ito and Kurib.) Drechs. ex Dastur, on the long arm of chromosome 5B. The highly susceptible cultivar, 'Rescue' (R), has the dominant, epistatic allele, crr. The crossover distance from the centromere to this gene was estimated in the genetic background of both Cadet and Rescue. The ditelosomic for the long arm of each of the lines Ct"5BL (Crr) and Rt"5BL (crr) was crossed by the corresponding reciprocal chromosome 5B substitutions, C-R5B (crr) and R-C5B (Crr). The F1's, heterozygous for both the telocentric and the alleles, were then backcrossed by the appropriate recessive lines, Cadet and R-C5B. Each backcross plant was tested for its reaction to root rot and examined cytologically for the presence of a telocentric chromosome. The recombination frequency of the centromere, marked by the presence or absence of the telocentric, with alleles at the Crr locus was 42.9 ± 3.4% in the Cadet background. In the Rescue background, the recombination frequency was 36.1 ± 3.3%. The difference is attributed to a generally lower chiasma frequency in Rescue than in Cadet.