bluuebunny/crossref_metadata_2025 huggingface dataset:
CHROMOSOME STABILITY IN MAIZE (ZEA MAYS) TISSUE CULTURES AND SECTORING IN SOME REGENERATED PLANTS
Authors: McCoy T. J. , Phillips R. L.
Published: November 2014

Cytogenetic stability of maize (Zea mays L.) tissue cultures was assessed by meiotic analysis of plants regenerated from 4- and 8-month-old tissue cultures and by mitotic analysis of cultured cells 4 and 8 months after culture initiation. Cultures initiated from four embryos each of W22 R-nj R-nj × A188 and A188 × W22 R-nj R-nj were examined. After four months in culture, only one of 65 regenerated plants was abnormal; after eight months, only four of 59 regenerated plants were abnormal. Three of the five abnormal plants had normal and cytogenetically abnormal sectors in the tassels. Inheritance studies were conducted on 51 regenerated plants. Eight plants segregated in the S1for recessive mutations resulting in defective kernels, and one plant segregated for a recessive mutation resulting in a wilted phenotype. Eight different plants that produced normal S1progeny segregated for defective kernel mutations in some S1families, indicating a lack of concordance between male and female reproductive cells in the original regenerated plant. The cytogenetic stability observed in regenerated plants also was observed in vitro, indicating that selection at the time of regeneration did not occur. Four hundred and thirty-four (97%) of the 449 cells analyzed in 4-month-old cultures had the normal 20-chromosome complement; 377 (95%) of the 398 cells analyzed in 8-month-old cultures were normal. These results indicate that chromosome stability is maintained in tissue cultures of A188 × W22 R-nj R-nj maize.
ISOLEMENT ET CHARACTÉRISATION DE MUTANTS SENSIBLES OU RÉSISTANTS À L'OZONE CHEZESCHERICHIA COLIB
Authors: Poliquin L. , Hamelin C. , Chung Y. S.
Published: November 2014

Escherichia coli B strains, either more sensitive or resistant to ozone than wild-type (OZsor OZr), were obtained after mutagenesis. OZsstrains carrying a mutation in ozrA or orzB, two genes located on both sides of malB, appeared as phenotypically different with regards to radio-sensitivity and cellular filamentation. OZrstrains, on the other hand, probably carry an allele of ozrA but were radioresistant and divided normally even with induction. A single gene (ozrA) thus seems to determine three levels of sensitivity to ozone, sensitivity to radiation and cellular filamentation in this organism. The possible involvement of a specific endonuclease in the repair of ozone-induced DNA lesions is considered.
INHERITANCE OF A SHORT-INTERNODE TRAIT IN TOBACCO
Authors: Legg Paul D. , Collins G. B.
Published: November 2014

A short-internode mutation in burley tobacco (Nicotiana tabacum L.) was inherited as a monogenic trait. Heterozygous plants varied in phenotype from comparable to the short-internode mutant to intermediate between mutant and normal plants. In generations following crosses between the mutant line and three burley cultivars, the degree of expression of dominance varied by years, maternal parent, cultivar background, and percentage of germplasm from the mutant parent. The short-internode line was reduced in plant height and had narrower leaves than the three cultivars. Also, the mutant line had more leaves than two of the three cultivars and was comparable to the cultivars in yield and several chemical components. Short-internode cultivars could be developed for use in present production or in mechanized handling systems.
CHROMOSOME BANDING HOMOLOGIES OF A TANDEM FUSION IN RIVER, SWAMP, AND CROSSBRED BUFFALOES (BUBALUS BUBALIS)
Authors: Bongso T. A. , Hilmi M.
Published: November 2014

The chromosomes of the Murrah (River), Swamp (Malaysian kerbau), F1 hybrid (Murrah × Swamp) and first generation backcross (F1 hybrid female × Murrah male) buffaloes (Bubalus bubalis L.) were studied using Giemsa (G) and centromeric (C) banding techniques. The diploid chromosome number for the Murrah was 2n = 50, Swamp 2n = 48, F1 hybrid 2n = 49 and two backcross animals had 2n = 49 and 2n = 50, respectively. The largest two metacentric chromosomes of the Swamp resulted from a tandem fusion between the two chromosomes 4p and 9, respectively, of the Murrah karyotype. The F1 hybrid (2n = 49) and one of the backcrosses (2n = 49) had karyotypes intermediate to the Murrah and Swamp parents. The C banding patterns were useful in identifying the X and Y chromosomes of the buffalo and demonstrated that a major portion of the centromere region of chromosome 9 was not incorporated into chromosome 4 during the tandem fusion.
AN INTERSTITIAL PERICENTRIC INVERSION INNEUROSPORA
Authors: Barry Edward G. , Leslie John F.
Published: November 2014

In ln(IL; IR)OY323 of Neurospora crassa, a long central segment of linkage group I is inverted that includes the centromere. This is the first interstitial pericentric inversion to be identified in a fungus. In genetic and cytological behavior, it resembles chromosome inversions in higher eukaryotes. In crosses heterozygous for the OY323 inversion, normally distant markers are closely linked, while in homozygous inversion crosses the gene order is reversed, but recombination is approximately normal within the inverted segment. A characteristic inversion loop may form at pachytene in heterozygous crosses; frequently, segments distal to the breakpoints do not pair, however. Rearrangement breakpoints were mapped precisely by duplication coverage using appropriate recessive markers in crosses of OY323 with a partially overlapping inversion, In(IL→IR)NM176.
MITOCHONDRIAL VARIANTS OFNEUROSPORA INTERMEDIAFROM NATURE
Authors: Rieck A. , Griffiths A. J. F. , Bertrand H.
Published: November 2014

From a sample of 122 natural isolates of Neurospora intermedia collected recently from around the world, five variants had erratic stop-start growth patterns reminiscent of the phenotype of "stopper" laboratory extranuclear mutants of Neurospora crassa. Like laboratory isolated mutants, the natural "stopper" variants were sterile as protoperithecial parents and transmitted the variant growth phenotypes very inefficiently, if at all, as male parents. Heterokaryon tests could not be made because of strain incompatibilities. Four of the variants have mitochondrial cytochrome aa3and b deficiencies. These four variants are all defective in mitochondrial ribosome assembly and have abnormal ratios of large to small subunits. Restriction enzyme analyses revealed some similarity of N. intermedia to N. crassa mtDNA. One normal and four variant strains had additional DNA in comparison to a standard normal strain. Cumulatively, the results indicate that the genetic alterations which cause stopper phenotypes of these natural isolates of N. intermedia are of mitochondrial rather than nuclear origin.
GOSSYPOL — AN EFFECTIVE MALE CONTRACEPTIVE WAS NOT MUTAGENIC IN SPERM HEAD ABNORMALITY ASSAY IN MICE
Authors: Majumdar S. K. , Ingraham H. J. , Prymowicz D. A.
Published: November 2014

Gossypol acetic acid, a potential male anti-fertility compound, was investigated for its mutagenic effects in the mouse sperm head abnormality assay. Compared with the controls, the chemical at 20 and 40 mg/kg doses did not increase detectable sperm head abnormalities in mice.
THE GENETICAL DIFFERENCE BETWEEN THE DBA/2 AND C57BL/6 STRAINS IN CORTISONE-INDUCED CLEFT PALATE
Authors: Vekemans M.
Published: November 2014

The DBA/2 strain of mice is about five times more sensitive than the C57B1/6 strain to cortisone-induced cleft palate. There is a matroclinous reciprocal cross difference. Appropriate backcrosses indicate that the basis of this reciprocal cross difference is not cytoplasmic. A biometric model including additive and dominance components adequately explains the data. Since dominance has been demonstrated in other strains and crosses, it is suggested that a trait correlated to cortisone-induced cleft palate has been exposed to directional selection.
THE BEHAVIORAL AND PHYSIOLOGICAL COMPONENTS OF MALATHION RESISTANCE INDROSOPHILA MELANOGASTER
Authors: Pluthero F. G. , Singh R. S. , Threlkeld S. F. H.
Published: November 2014

Three parallel lines of Drosophila melanogaster were selected with different concentrations of the insecticide malathion over a period of 70 generations. Periodic assays found that the resistance of the adult and pre-adult stages increased at a rate proportional to the selection intensity. Ultimately all selected populations achieved similar levels of resistance. Relaxation of selection resulted in resistance drop-offs to pre-selection levels, while continued selection maintained resistance at a constant level. The results suggest that physiological resistance and behavioral response to malathion have distinct genetic bases, and that resistance of adults and larvae are also under independent genetic control.
RESPONSE OF MALE GERM CELLS OF MOUSE TO ACUTE AND FRACTIONATED DOSES OF 131I INDUCED RADIATION
Authors: Reddy P. P. , Reddy S. B. , Ebenezer D. N. , Reddi O. S.
Published: November 2014

The effects of radioactive iodine in acute as well as fractionated doses on male germ cells were studied. 131I in four acute doses of 10, 15, 20 and 25 μCi was given intraperitoneally. For fractionated doses, 12.5 μCi was given twice with an interval of 24 h. A dose relationship was exhibited between the concentration of radionuclide and the survival fraction of type A spermatogonia, intermediate and type B spermatogonia and preleptotene spermatocytes. The maximum depletion was recorded after 25 μCi. The survival values for this dose group were 40.4, 51.4, and 25.0% for type A cells, intermediate and type B cells and preleptotene spermatocytes, respectively. Fractionated doses of radioiodine also reduced the survival rate of gonadal cells and are more effective than 20 μCi acute dose in decreasing the survival fraction of all types of gonadal cells.
Genetic analysis of the BB/W diabetic rat
Authors: Butler L. , Guberski D. L. , Like A. A.
Published: November 2014

A large colony of BB/W diabetic rats has been developed as a research model for insulin dependent, type 1 diabetes mellitus. The foundation stock had 8% diabetics which appeared in a sporadic manner. The Worcester (W) colony was inbred by brother × sister matings for 11 generations and the proportion of diabetics increased to over 50%. The age of detection varies from 46 to 250 days. For selection purposes, classification was made at 120 days, which means that 15 to 20% potential diabetics were classified as normal. Evidence from different analyses indicates that the inheritance of diabetes is by a recessive gene or gene cluster with 50% penetrance at 120 days. The selection of breeding stock from diabetic parents raised the proportion of diabetics produced by two normal parents from 12 to 43%. Diallel tests show that diabetic and normal offspring of two diabetic parents have the same diabetic gentoype. Outcrosses to other strains of rat indicate that the trait is transferred as a recessive with only 3% diabetics recovered in the F2 where noninbred BB stock was used as the diabetic source, and 36% where partially inbred BB/W was used as the diabetic parent. Since the proportion of diabetics produced by all types of crosses has changed, and may continue to change with changes in the genetic background, we have used the operational term penetrance to describe the frequency of diabetes in individuals homozygous for the diabetes gene cluster. At present the penetrance at 120 days is 59% in the BB/W colony.
Characterization and banding of mitotic chromosomes from two established cell lines of the German cockroach Blattella germanica
Authors: Krawczun Michael S. , Mukherjee Asit B.
Published: November 2014

A detailed analysis of karyology, chromosome measurement, and chromosome constitution in different cell populations from two established cell lines of the German cockroach Blattella germanica is provided. All 12 pairs of chromosomes in somatic cells are clearly identifiable. All chromosomes except No. 5 display distinct C- bands. The G- and Q-banding patterns are not consistent, but many cross bands were observed. The N-banding pattern is reproducible and quite similar to the C-banding pattern. The cells in vitro as compared with cells in vivo are found to be extremely suitable for analysis of chromosomes of this species.
Effects of parental age and sampling method on response to index selection in Tribolium castaneum
Authors: Patterson D. L. , Friars G. W. , McMillan I.
Published: November 2014

Two generations of individual selection on the basis of an index incorporating the 13th day larval weight and pupal weight were carried out using Triboliumcastaneum. The experimental design consisted of two sampling methods by three parental ages and was repeated three times concurrently (three sets). Eight offspring for each of 10 families per set were measured. Heritabilities and phenotypic and genetic correlations for larval and pupal weights were estimated using variance components. Age of parents had an effect on response to selection for total merit. Offspring of older parent stocks had heavier larval weight. Sampling parents from one subpopulation versus sampling from a group of subpopulations had no consistent effect on total merit. Although the overall effect of set was not significant, interactions of set with sampling method and parental age were significant, indicating that control of these factors might reduce among replicate variation commonly seen in selection experiments.
Genetics of Gibberella fujikuroi. 1. Inheritance of certain cultural traits
Authors: Sidhu Gurmel S.
Published: November 2014

Gibberella fujikuroi (conidial stage Fusarium moniliforme) is a pathogen of many crop species. It exhibits a tremendous cultural and pathogenic variability in the field through sexual and parasexual cycles. This report investigates the inheritance of mating type, colony color, colony morphology, and colony growth rate. The tetrad and random ascospore analysis of variants of these traits, obtained from nature and through mutagenesis, confirm that they are controlled by single nuclear genes. The genes for colony morphology and colony growth rate were linked whereas other genes show independent assortment. These traits can be used as genetic markers in the infection process of this fungus.
Nondisjunction in canaries: data of Durham (1926)
Authors: Sittmann K.
Published: November 2014

The largest controlled breeding experiment with canaries, conducted 70 years ago under the auspices of William Bateson (F. M. Durham and D. C. E. Marryat, 1908. Royal Society of London, Reports to the Evolution Committee, Report 4: 57–60.), involved 1300 birds with either black or pink eye color. The difference is governed by two alleles at the Z-linked cinnamon locus. Crosses between pink-eyed males (bb) and black-eyed females (BW) produced unexpected pink sons and black daughters that are attributed to primary nondisjunction in meiosis II of spermatogenesis. Several interdependent estimates of the incidence of nondisjunction progeny range up to 16 ± 3%. Cytological evidence is lacking for Durham's (F. M. Durham. 1926. J. Get. 17: 19–32.) and other presumptive nondisjunction cases in the contemporary literature comprising canaries, doves, and pigeons.
The maintenance of polymorphisms at two loci in house mouse (Mus musculus) populations
Authors: Petras Michael L. , Topping John C.
Published: November 2014

To determine the roles of mutation, migration, and selection in maintaining genetic variability in populations of house mice (Mus musculus), stochastic models based on characteristics of mouse populations inhabiting corn cribs in southwestern Ontario and the t allele were developed. Two sets of models were examined. One involved selection against t/t mice and a migration rate of 0.05 to 0.10 (low migration model) whereas the other involved selection against both t/t and +/t genotypes and a migration rate of 0.33 (high migration model). Both models could account for the t allele frequencies observed in natural populations. Similarly both models explain the frequencies observed at a second polymorphic locus, the Hbb locus which controls the β chain of the hemoglobin molecule, provided strong selection favoring the Hbb heterozygotes is incorporated. Without such selection pressure rapid extinction of one of the alleles at this locus occurred. A stabilizing force such as selection is considered necessary for the hemoglobin polymorphism observed in the populations under consideration. Evidence supporting the high migration model as the more realistic is also presented.
Kernel-weight effects and transmission of a partial trisome involving the long arm of chromosome 5 in maize
Authors: Beckett J. B.
Published: November 2014

Effects of trisomy for a portion of the long arm of chromosome 5 of maize (Zea mays L.) were explored by using the B5La element derived from the B–A translocation TB-5La. In one family, the B5La chromosome was transmitted through the egg to half of the offspring; in two other families, the rate of transmission was 44 and 46%, respectively. From the reciprocal cross, only 5.6% of the progeny carried B5La. The presence of the allele Pr (purple aleurone) on the partial trisome made it possible to study the effect of trisomy for a portion of the long arm of chromosome 5 on kernel weight. The trisegmental kernels averaged 11% lighter than their disomic sibs on seven ears and were of the same weight on one ear. It appears that the particular alleles of genes on B5La originally reduced kernel weight, but one variant, presumably acquired by crossing over, did not. Crossover products involving an exchange between the translocation breakpoint on B5La and the pr locus occurred at a rate of 8.3%.
Griffing and Hayman diallel analyses of protein and lysine content of spring triticale
Authors: Mather D. E. , Poysa V. W.
Published: November 2014

Data on the percent protein, protein per grain, and lysine content of grain protein in a 6 × 6 diallel cross of triticale (× Triticosecale Wittmack) were analyzed by both the Griffing and the Hayman diallel methods. Results agreed with those of a previous analysis of the same data by the gene effects method. No advantage of diallel analysis over gene effects analysis was indicated. Parallel use of the Griffing and Hayman analyses illustrated the relationship between these two diallel methods. Gene action was mainly additive for the three traits, although some dominance was detected for percent protein and protein per grain. Dominance for protein per grain was in the direction of higher protein. Variation in lysine content was largely attributable to variation in percent protein, protein per grain, and grain plumpness. Selection of parents on the basis of the Griffing general combining ability effects would be similar to selection on the basis of parental phenotype.
Genetics, cytology, and crossing behavior of an alfalfa (Medicago sativa) mutant resulting in failure of the postmeiotic cytokinesis
Authors: McCoy T. J. , Smith L. Y.
Published: November 2014

During pollen investigations on diploid alfalfa (Medicago sativa L.) several plants were identified which produced "jumbo" pollen. The cause of the jumbo pollen is failure of the postmeiotic cytokinesis. These plants produce a single, four-nucleate microspore from one microspore mother cell (MMC) rather than the normal four, single-nucleate microspores from one MMC. Subsequent gametophyte development is characterized by fusion of the four nuclei into a single nucleus in most cases (range of 80 to 100%), followed by a developmental sequence comparable to normal alfalfa. Mature 4n male gametophytes are thus formed from 2n sporophytes. Genetic control of the postmeiotic cytokinesis failure is by a single recessive gene, designated jp. Although a low frequency of jumbo pollen does germinate (range of 3.1 to 37.8%), crossing studies demonstrate jumbo pollen is incapable of effecting fertilization. The use of the jp mutant in breeding studies, and interspecific hybridization research, is discussed.
Selection for light preference during ovipositing in Drosophila pseudoobscura
Authors: Seiger Marvin B. , Sanner Amelia Broach
Published: November 2014

Selection was carried out on a population of Drosophila pseudoobscura to obtain lines preferring high-light intensity or low-light intensity during oviposition. This species is generally characterized as preferring low-light intensities. It was possible to select for increased preference for high-light intensity, but not for low-light intensity during oviposition. However, additive genetic variability exists in preferences for both high- and low-light intensities. The original population was probably operating at a photonegative extreme for oviposition, yet maintained enough genetic variability to permit selection toward a photopositive preference.
The meiotic behaviour of natural F1 hybrids between Trimerotropis suffusa Scudder and T. cyaneipennis Bruner (Orthoptera: Oedipodinae)
Authors: John Bernard , Lightfoot David C. , Weissman David B.
Published: November 2014

Trimerotropis suffusa Scudder is a species which ranges from the Rocky Mountains to the Californian Sierras and the Cascade Mountains of Oregon. Additionally, to the south, it is found along the coast of California to Mendocino County. Trimerotropis cyaneipennis Bruner has a distribution from West Texas through New Mexico, Arizona, Colorado, Utah, and Nevada to southern Oregon and southern California. These two species are most commonly ecologically isolated from each other, the latter generally occurring in desert regions or those with sparse vegetation whereas T. suffusa is found in woodland situations (Strohecker et al. 1968). Even where they approximate in their distributions, the ecotones which separate them are normally broad enough to preclude contact between them. These species have, however, been found in microsympatry in a narrow ecotone in the Pueblo Mountains of Southeast Oregon. Hybrid individuals intermediate in morphology, crepitation, and diploid chromosome number occur within this ecotone. A meiotic analysis of three such hybrid males indicates that the parental species are distinguished by a fixed centric fusion. This difference tends to be obscured in the parental karyotypes which both contain a variable number of metacentric chromosomes, some fixed and some polymorphic, of inversion origin. Meiotic behaviour also identifies two potential sources of infertility in these hybrids. First, irregular segregation of the fusion chromosomes, following either linear orientation of the three-multiple chain or else from failure of the chain to form. Second, pairing failure, usually in one less commonly in two, of the autosomal pairs not involved in the fusion system. The extent of these anomalies varied between the three hybrid individuals indicating that genotypic differences between the parents also play a role in determining multiple orientation and the levels of pairing failure in both the multiple and in the other autosomes which form univalents. The univalents that do form may either segregate at random or may lag on the first division spindle. In the latter event they inhibit cytokinesis at first division, and sometimes also at second division, giving rise to macrospermatids which are, respectively, diploid (2x) or tetraploid (4x). The net result of such an anomalous meiosis is that most of the sperm produced by all three hybrids is either polyploid or aneuploid.
Isolation of multiple mutants of Pseudomonas aeruginosa capable of efficient thymine salvage
Authors: Potter Andrew A. , Loutit John S.
Published: November 2014

Mutants of Pseudomonas aeruginosa strain 1 which incorporate relatively large amounts of thymine into their DNA were isolated. Three steps were required to produce this phenotype. First, strains constitutive for thymine uptake and catabolism were isolated, followed by selection for mutants which could not catabolize thymine. The double mutant was then used to isolate a strain exhibiting greater sensitivity to the thymine analog 5-bromouracil. Efficient DNA-specific pulse labelling with isotopic thymine was successfully carried out with this strain.
Structural changes of Ag-stained nucleolus organizing regions and nucleoli during meiosis in Allium flavum
Authors: Loidl Josef , Greilhuber Johann
Published: November 2014

Microsporogenesis of Allium flavum was investigated by light microscopy using a silver impregnation technique. Ag-positive structures were present at the nucleolus organizing regions (NORs) in all stages of the meiotic cycle. During prophase I the nucleoli were found to be composed of a strongly impregnated central and a weakly impregnated peripheral component, probably corresponding to the pars fibrosa and pars granulosa, respectively. A heteromorphism with regard to the presence of a NOR allowed the determination of the crossing-over frequency in the chromosome arm concerned.
Genome size of man and animals relative to the plant Allium cepa
Authors: Greilhuber J. , Volleth M. , Loidl J.
Published: November 2014

A direct Feulgen-cytophotometric comparison of the genomic DNA content (C value) was performed between the liliaceous plant species Allium cepa and a number of animal species to reassess the genome size ratios between plants and animals. These appeared unduely ambiguous as a consequence of divergent picogram estimates in several animal reference species. Taking 1C = 16.75 pg for Allium cepa, the estimates were (1C value in picograms): man, 3.11; Indian muntjak CCL 157 cell line, 2.68; domestic pig, 2.79; Chinese hamster, 2.66; CHO cell line, 2.73; laboratory rat, 2.65; mouse, 3.04; rat kangaroo Pt-K2 cell line, 4.21; fowl, 1.16; and the green toad, 4.30. These values are consistent with a number of independent absolute and relative DNA content determinations reported for animals, and therefore define a coherent set of animal and plant reference values for genome size determinations.
Polyhaploids from a cross between Hordeum vulgare and the amphiploid (Hordeum jubatum and Hordeum compressum)
Authors: Starks Gilbert D. , Tai William , Steidl Robert P.
Published: November 2014

Polyhaploids were obtained through the reduction of ploidy levels from a cross between a synthetic hexaploid amphiploid Hordeum jubatum L. and Hordeum compressum Griseb. and Hordeum vulgare L. The purpose of this work was to make a comparative study of the cytology, fertility, and morphology of the five polyhaploids and the amphiploid. Three of the polyhaploids were triploids, one had a variable chromosome number, and a fifth polyhaploid approached a pentaploid constitution. Mechanisms for the origin of the polyhaploids are suggested including those for the elimination of Hordeum vulgare chromosomes.
Characterization of the canine karyotype by counterstain-enhanced chromosome banding
Authors: Mayr B. , Schweizer D. , Schleger W.
Published: November 2014

The application of the counterstain-contrasted fluorescent banding technique to canine chromosomes provided an improved capability to highlight specific heterochromatic regions and to produce well defined banding patterns both on mitotic and meiotic chromosomes. Triple staining with chromomycin A3 – distamycin A – DAPI revealed the occurrence of DA – DAPI positive heterochromatin in chromosomes 33, 36, 37, and 38. Pachytene nuclei present more favourable material for the detection of very small amounts of DA – DAPI material than mitotic division stages. Counterstain-enhanced chromomycin R-banding greatly facilitated chromosome identification. A standard R-band karyotype of Canis familiaris is proposed and described in some detail. DAPI – actinomycin D staining produced a QFH-type banding pattern and enhanced differentiation of some polymorphic regions.
High-resolution idiogram of Giemsa R-banded human prophase chromosomes
Authors: Richer C. L. , Drouin R. , Murer-Orlando M. , Jean P.
Published: November 2014

The schematic representation of RHG-banded chromosomes (R-banding was produced by heat denaturation followed by Giemsa staining (RHG)) in the 850-band range per haploid set, was prepared showing the relative position, the specific size, and the characteristic staining intensity for each band. To this idiogram was adapted the new International Standard Cytogenetic Nomenclature. Our aim was to produce a realisitic idiogram which could help in the preparation of R-banded prophase karyotypes and in the localization of chromosomal rearrangements. A comparative analysis of bands at prophase and metaphase revealed certain aspects of the dynamics involved in chromosome condensation and in R-band organization. The effect of chromosome elongation on the appearance of R-bands within heterochromatic regions has also been discussed.
Nucleolar competition analysis in Aegilops ventricosa and its amphiploids with tetraploid wheats and diploid rye by the silver-staining procedure
Authors: Orellana J. , Santos J. L. , Lacadena J. R. , Cermeño M. C.
Published: November 2014

The nucleolar organizer activity of Aegilops ventricosa and its amphiploids with tetraploid wheats (Triticum turgidum, Triticum dicoccum, and Triticum aethiopicum) and diploid rye (Secale cereale) was analyzed by the silver-staining procedure. Triticum turgidum and Triticum dicoccoides show four Ag-NORs (silver-stained nucleolar organizer regions), in agreement with previous data. Only two Ag-NORs are detected in Ae. ventricosa (genome constitution DDMM) indicating that natural amphiplasty occurs in this allotetraploid species. No amphiplasty was observed in the Ae. ventricosa – tetraploid wheat amphiploids since six Ag-NORs were visible in all of them. On the contrary, only two Ag-NORs were detected in the Ae. ventricosa – Secale cereale amphiploid, the rye NORs being suppressed by the presence of ventricosa chromosomes. The ventricosa NORs therefore are codominant with those of tetraploid wheat (chromosomes 1B and 6B) and dominant to chromosome 1R of rye. Eleven T. aestivum – Ae. ventricosa addition lines have been also analyzed. All of them showed four Ag-NORs. Clear-cut conclusions were not reached since the added ventricosa chromosomes were not identified.
Observations on chromosomal male sterility in Drosophila melanogaster
Authors: Stone James. C.
Published: November 2014

Observations on a variety of metazoans have shown that the X chromosome becomes functionally inactive earlier in male meiosis than the remainder of the genome. Genetic analyses of male-sterile chromosome rearrangements in Drosophila suggest that the X chromosome in this species behaves as a distinct functional unit, and have further suggested that X-chromosome expression is regulated in the primary spermatocyte by a cis-acting control element located in the centromeric heterochromatin. Attempts to test the X-inactivation hypothesis of chromosomal sterility in Drosophila and attempts to map the hypothetical control element are described here. Cytological observations on a male-sterile X-autosome translocation are also discussed.
The estimation of fitness in iteroparous species during population replacement experiments
Authors: Barclay Hugh J.
Published: November 2014

A model is proposed for a species with overlapping generations near equilibrium. This model incorporates a standard strain in competition with a strain carrying compound chromosomes. A method of estimating the relative fitness of the compounds is described and tested by Monte Carlo simulation. The results show that the method is robust and can be used over a variety of life history patterns for estimating fitness and, with less precision, generation time.
Latent male fertility in 'Cornerstone' chromosome 4A
Authors: Islam A. K. M. R. , Driscoll C. J.
Published: November 2014

A latent gene(s) for male fertility has been detected in 'Cornerstone' chromosome 4A. Although this gene(s) is unable to effect fertility in 'Cornerstone' itself, it is able to do so in the presence of a male-fertility gene(s) in modified barley chromosome 4Hm. Furthermore, a dosage effect of this latent gene(s) is evident, as increases in male fertility are observed in plants possessing one modified barley chromosome 4Hm and zero, one, or two doses of 'Cornerstone' chromosome 4A. The Y line, involving 'Cornerstone' and a single barley chromosome 4Hm, is almost as fertile as euploid wheat.
Genetic variability among and within closely spaced populations of lodgepole pine
Authors: Knowles Peggy
Published: November 2014

The genetic composition of Pinus contorta var. latifolia as determined by isozyme analysis was assessed and examined at two hierarchical levels; within closely spaced populations and within adjacent subpopulations. Four populations of lodgepole pine consisting of 125 trees each were sampled along an elevational gradient spanning a distance of approximately 2 km in the Front Range of the Rocky Mountains in Colorado. Each population was further divided into five subpopulations. Four isozymes were electrophoretically resolved from needle tissue removed from each tree. Statistics characterizing the genetic structure were calculated including measures of genetic variability, tests of allelic heterogeneity, and F statistics. The results indicate that lodgepole pine has a relatively low level of genetic variation with 44% of its loci polymorphic, an average of 1.33 alleles per locus, heterozygous at 13.5% of their loci, and a polymorphic index of 0.144. Slightly less than 1% of the observed genetic variability resided among the four populations with the remainder residing among the individuals within populations. A slight deficiency of heterozygotes was indicated by the F statistics analysis. Allelic distributions at the subpopulation level indicated that clustering was evident although not a predominant characteristic of the genetic pattern. It is suggested that inbreeding and (or) the pooling of individuals from different breeding groups are likely phenomena contributing to the genetic pattern in lodgepole pine over microgeographical distances.Key words: genetic variability, lodgepole pine, Pinus contorta var. latifolia, isozyme.
The dynamics of B chromosomes in populations of the Australian plague locust, Chortoicetes terminifera (Walker)
Authors: Gregg P. C. , Webb G. C. , Adena M. A.
Published: November 2014

The B chromosomes of Chortoicetes terminifera possess an accumulation mechanism. B chromosomes were transmitted at a rate of 0.766 in one B(♂) × zero B(♀) crosses and 0.477 in zero B(♂) one × B(♀) crosses. In crosses where the female had a B chromosome, there were significant differences in transmission rates between pods, but these were not related to differences in G-banding patterns of the B chromosomes involved. In crosses where either the male or female parent had two B chromosomes the B chromosomes did not segregate perfectly, nor did they segregate in a random fashion. The closest resemblance to the behaviour of normal bivalents occurred when the two B chromosomes were of the same, rather than different, G-banding variants, and when they were present in the male rather than the female parent. B chromosomes occurred at eight localities scattered throughout New South Wales. No locality was found where they were not present. The average frequency of B chromosomes was 14.0% for one-B individuals and 0.8% for two-B individuals. There were no significant differences in B-chromosome frequency between males and females. Of the eight localities, only one had a B-chromosome frequency significantly different from any other locality. This relatively uniformity of B-chromosome distribution is interpreted as a consequence of the migratory nature of C. terminifera. A model was constructed to simulate the dynamics of B chromosomes in locust populations. Three main dynamic patterns were recognized, and these were related to differences in the fitness of one-B and two-B individuals. It was concluded that the B chromosome of C. terminifera is probably parasitic, although the simulation model revealed some difficulties which suggest that caution should be applied to the description of any B chromosome as purely parasitic.Key words: B chromosomes, locust, meiotic drive, G-banding, fitness. Chortoicetes terminifera (Walker).
Genetics of speciation in the Aedes (Stegomyia) scutellaris subgroup (Diptera:Culicidae). 4. Chromosomal relationships of Aedes cooki with four sibling species
Authors: Sherron David A. , Rai Karamjit S.
Published: November 2014

Morphology and behavior of chromosomes and development of testes and sperm were examined in hybrids from interspecific crosses involving Aedes cooki and four sibling species of the Aedes (Stegomyia) scutellaris subgroup of mosquitoes. The degree of abnormality in hybrid spermatogenesis in interspecific crosses involving Aedes cooki males and females of four sibling species paralleled the geographic distributions of these species and the genetic divergence indicated by other genetic studies. Hybrids from crosses involving Aedes malayensis females and Aedes cooki males were characterized by atrophied testes and extensive chromosome breakage. Hybrids from crosses involving Aedes alcasidi females and Aedes cooki males suggested a possible pericentric inversion distinguishing the largest autosome of Aedes alcasidi from that of Aedes cooki. Hybrids from interspecific crosses involving females of Aedes polynesiensis and Aedes pseudoscutellaris and males of Aedes cooki showed high percentages of univalents of the smallest chromosome pair. Hybrid spermatogenesis in two interspecific crosses involving Aedes cooki females differed from results of reciprocal crosses. Data were scant, however, and interpretation was difficult in view of negligible hatch in all interspecific crosses involving Aedes cooki females.Key words: Aedes, inversion, phylogeny, hybrid dysgenesis.
A study on somatic association and its relevance to meiotic pairing using haploids of barley (Hordeum vulgare, n = x = 7)
Authors: Bhambhani R. N. , Kuspira J. , Kenny J. , Sadasivaiah R. S.
Published: November 2014

The spatial distributions of three readily identifiable chromosomes in somatic cells of monoploid barley (Hordeum vulgare, n = x = 7), as determined by the measurements of distances between them, were compared with the theoretical random distribution. None of the three distributions were found to be significantly different from the theoretical. It was therefore concluded that the three nonhomologous chromosomes in barley do not exhibit the propensity for somatic association. The implications of these results to nonhomologous pairing observed during meiotic prophase of barley monoploids are also discussed.Key words: Hordeum, barley, somatic associations, meiotic pairing, chromosome positions.
Effect of temperature on transition and transversion mutagenesis: characterization of wild type and a mutator T4 DNA polymerase mutant
Authors: Reha-Krantz Linda J. , Parmaksizoglu Sükran
Published: November 2014

The effect of temperature on genetically well-defined mutational pathways was examined in the bacteriophage T4. The mutational site was a T4 rII ochre mutant which could revert to rII+ via a transversion or to the amber convertant via a transition. Temperature did not strongly affect any of the pathways examined in a wild-type background; however, increased temperature reduced the mutational activity of a mutator DNA polymerase mutant. Possible models to explain the role of temperature in mutagenesis are discussed as well as the significance of low temperatures for in vitro mutagenesis reactions.Key words: bacteriophage T4, mutator, transition, transversion, temperature effects.
Chromosome fusions in cultured cells of celery
Authors: Murata Minoru , Orton Thomas J.
Published: November 2014

A 6-month-old cell suspension culture of celery (Apium graveolens var. dulce cv. Tall Utah 52-70R) exhibited both numerical and structural changes in chromosomes. Approximately 50% of the cultured cells had a normal chromosome number (2n = 22); however, 42% were hypodiploid cells (2n = 17–21). The most frequent structural change was chromosome fusion, which was observed in 44% of the cells analyzed and was highly associated with hypodiploidy. Chromosome fusions seemed to occur among any two or more of the chromosome components, but preferentially involved short arms of acrocentrics. This suggests that heterochromatic terminal ends or telomeres, particularly late DNA-replicating regions, would play an important role for inducing chromosome fusions. Furthermore, a very high frequency of fusions in the cultured cells of this study suggests that the occurrence of fusion might be a primary source of other structural changes such as translocations, duplications, and deficiencies observed in older cultures.Key words: Apium, hypodiploidy, chromosome fusion, tissue culture, celery culture.
The effect of cytoplasm on cold hardiness in alloplasmic rye (Secale cereale L.) and triticale
Authors: Limin A. E. , Fowler D. B.
Published: November 2014

Many changes occur within the cytoplasm of plant cells during cold acclimation. However, the cause and effect relationship between cytoplasmic response to low temperature and the development of cold hardiness in cells has been difficult to determine. This study considered the importance of rye (Secale cereale L.) and wheat (Triticum aestivum L. and Triticum tauschii (Coss.) Schmal.) cytoplasmic effects in conditioning plant cold hardiness. The cold hardiness of octoploid triticale (× Triticosecale Wittmack) produced from hardy rye and nonhardy wheat was similar to that of the wheat parent, demonstrating a complete suppression of the rye cold hardiness genes. Similar observations were made for wheat – rye amphiploids from reciprocal crosses, indicating that this suppression was not due to cytoplasmic effects. It is more probable that, because the cold hardiness of octoploid triticale approximates that of the wheat parent, the cold hardiness potential of the rye genome is suppressed by a gene or genes in the wheat complement. The cold hardiness of alloplasmic rye with T. tauschii cytoplasm was similar to that of the rye parent indicating that the cold hardiness genes of rye have normal expression in the T. tauschii cytoplasm. Based on observations made in these two studies, it was concluded that the cytoplasm has little direct effect on cold hardiness, or on the nuclear expression of cold hardiness.Key words: cold hardiness, cytoplasm, Triticum aestivum L., triticale, alloplasmic rye.
Interstrain differences for larval dispersal and egg cannibalism in the flour beetle, Tribolium castaneum
Authors: Mayes Paul A. , Englert DuWayne C.
Published: November 2014

Egg cannibalism rates and degree of dispersal were examined for 14-day-old larvae of two genetic strains, wild type (+) and antennapedia (ap), of Tribolium castaneum in fractionable shell vials. Forty-eight treatment combinations of fixed placement levels for eggs (top, middle, bottom, and random) and larvae (top, middle, and bottom) were tested for each strain in three replicates. Following a 24-h treatment exposure period, measurements of egg cannibalism and larval position revealed that + larvae tended to disperse toward the bottom regardless of original placement position or egg type, while ap larvae tended to remain near the original placement position. Overall larval dispersal was affected by egg position. Egg cannibalism rate was higher for + larvae than ap larvae, and some degree of ap egg preference was exhibited by + larvae. No similar opposite genotype preference was exhibited by ap larvae.Key words: cannibalism, behavior, quantitative genetics, Tribolium.
Differentiation of four taxa of the Anopheles balabacensis complex using H-banding patterns in the sex chromosomes
Authors: Wibowo S. , Baimai V. , Andre R. G.
Published: November 2014

Analyses of metaphase chromosomes of four taxa of the Anopheles balabacensis complex (A. dirus A, B, and C, and A. takasagoensis) using the Hoechst 33258 staining technique have revealed remarkable differences in the fluorescence banding patterns of the sex chromosomes. These result from changes in the amount and distribution of constitutive heterochromatin. This evidence supports the results from cross-mating experiments and from morphological studies which indicate that three of these taxa, A. takasagoensis, dirus A, and dirus B, are sibling species. Differences in H-staining patterns of the sex chromosomes of a dirus colony from Kanchanaburi suggest that it too is a genetically distinct taxon, provisionally designated as dirus C, within the A. balabacensis complex.Key words: Anopheles, H-banding, heterochromatin, sex chromosomes.
Identification of the somatic chromosomes of Psathyrostachys fragilis (Poaceae)
Authors: Linde-Laursen I. , Bothmer R. von
Published: November 2014

The karyotype of the outbreeding P. fragilis (2n = 2x = 14) was investigated by Feulgen staining and by C-, N-, and Ag-banding techniques. The complement consisted of 14 large chromosomes, 8 metacentrics and 6 satellite (SAT) chromosomes, probably among the longest within the Poaceae. Two SAT-chromosome pairs carried small, and one pair carried minute, polymorphic, completely heterochromatic satellites. Each chromosome could be referred to one of the seven chromosome pairs by its C-banding pattern. The patterns comprised from zero to three conspicuous, but not large bands per chromosome resulting in an overall low content of constitutive heterochromatin (<4%). The C-banded karyotype of P. fragilis differed from any previously reported in the Triticeae. Six of seven chromosome pairs were polymorphic either for C-banding patterns or satellite size (or for both). N-banding gave no differential staining of chromosomes. Silver nitrate staining established that the nucleolar organizers had different nucleolus-forming capacities. The presence of the small and minute satellites was more consistently demonstrated after C- and N-banding than after Feulgen staining.Key words: Triticeae, Poaceae, karyotype, C-, N-, and Ag-banding.
Inheritance of needle tissue isozymes in Douglas-fir
Authors: Neale D. B. , Weber J. C. , Adams W. T.
Published: November 2014

Methods for resolving electrophoretic variants from extracts of needle tissue of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) are described, and the inheritance of 12 of at least 15 loci that control allozymes from 11 enzyme systems are established. Evidence for the inheritance of allozyme variants was obtained in three ways: (i) comparison in seed orchard clones of allozyme genotypes determined from both megagametophyte and needle tissue; (ii) analysis of segregating full-sib progenies of seed orchard clones; and (iii) comparison of needle allozyme pattern phenotypes to previously reported embryo phenotypes. Ten of the 12 loci (coding phosphoglucomutase, PGM(1) and PGM(2); glycerate dehydrogenase, GLYDH; phosphoglucose isomerase, PG1(2); glutamate dehydrogenase, GDH; glucose-6-phosphate dehydrogenase, G-6PD; 6-phosphogluconate dehydrogenase, 6-PGD(1); isocitrate dehydrogenase, IDH; diaphorase, DIA(2); malate dehydrogenase, MDH(1)) produce clear bands in seed tissue; however, glutamate oxaloacetate transaminase GOT(3) (N) was not found in seeds and shikimic dehydrogenase (SDH) could only be clearly resolved in needles (N). Several enzymes active in seed tissue could not be detected in needle tissues.Key words: Douglas-fir, needle tissue isozymes, inheritance.
Ultrastructure of androgenic microspores of barley during the early stages of anther culture
Authors: Chen C. C. , Howarth M. J. , Peterson R. L. , Kasha K. J.
Published: November 2014

Cultured barley anthers fixed every 2 days over the first 8 days of culture were examined by transmission electron microscopy. During this period, a small percentage of the microspore population developed into multicellular units. Marked changes in subcellular organization preceded and accompanied the formation of these multicellular structures. Events observed included nuclear fusion, increases in the number of mitochondria and dictyosomes, lipid storage, as well as elaboration of the pollen grain intine. Starch, first observed at day 6 in culture, increased progressively thereafter. Some of the ultrastructural observations correlated with ploidy increases in microspores reported previously.Key words: anther culture, barley, ultrastructure, microspores, androgenesis.