Search Results - (Author, Cooperation:R. Mott)

2018-09-29

The American Society for Biochemistry and Molecular Biology (ASBMB)

0021-9258

1083-351X

Biology

Chemistry and Pharmacology

2011-08-30

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Arabidopsis/classification/*genetics ; Arabidopsis Proteins/genetics ; Base Sequence ; *Gene Expression Profiling ; Gene Expression Regulation, Plant/*genetics ; Genes, Plant/genetics ; Genome, Plant/*genetics ; Genomics ; Haplotypes/genetics ; INDEL Mutation/genetics ; Molecular Sequence Annotation ; Phylogeny ; Polymorphism, Single Nucleotide/genetics ; Proteome/genetics ; Seedlings/genetics ; Sequence Analysis, DNA ; Transcription, Genetic/*genetics

2011-09-17

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Alleles ; Animals ; Animals, Laboratory/genetics ; Gene Expression Regulation/*genetics ; Genetic Variation/*genetics ; Genome/*genetics ; Genomics ; Mice/classification/*genetics ; Mice, Inbred C57BL/genetics ; Mice, Inbred Strains/*genetics ; *Phenotype ; Phylogeny ; Quantitative Trait Loci/genetics

2011-09-17

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Chromosome Breakpoints ; Exons/genetics ; Female ; Gene Expression ; Genetic Variation/*genetics ; Genome/*genetics ; Genomics ; Genotype ; Male ; Mice ; Mice, Inbred Strains/*genetics/immunology ; Mutagenesis, Insertional/genetics ; *Phenotype ; Quantitative Trait Loci/genetics ; Rats ; Retroelements/genetics ; Sequence Deletion/genetics

book

2016

College ; Diskriminierung ; Niedriglohn ; Arbeitsplatz ; Universität ; Hochschulzulassung ; Hochschule ; Student ; USA

English

2018-10-04

Genetics Society of America (GSA)

2160-1836

Biology

1399-3054

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Tissue cultures of Zea mays L. derived from four different somatic sources all appeared to grow as callus. Microscopic examination, however, showed this growth to be merely an aberrant root-like form.A continium in the degree of aberrant root behavior, ranging from cultures appearing very root-like to those visibly indistinguishable from callus, was recognized. The continuum and ultimately the callus appearance resulted from increasing inhibition of root elongation coupled with strong enhancement of branch root initiation. This aberrant form of root growth was apparent in all cultures observed. Tissue source and growth regulator treatment interacted to shift the growth form within the extremes of the continuum but in no case was the root-like mechanism of proliferation disrupted, even during extended subculture. Removal of exogenous growth regulators from the culture medium simply allowed outgrowth of existing root primordia as normal roots and this accounts for the characteristic ease of rhizogenesis from what has been called maize callus.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] These observations are pertinent because of frequent claims that the combined hydroxyproline of higher plants is present, virtually exclusively, in a protein moiety present in their cell walls and which, in advance of its isolation and purification, was named extensin6. This claim has been extended ...

Electronic Resource

0888-7543

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

1399-3054

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Five cereals and two related grasses were tested for adventitious shoot production from tissue cultures using methods concordant with those reported to be successful for cereals. The five cereals I wheat (Triticum aestivum L.), oats (Avena sativa L.), and maize (Zea mays L.) Pioneer hybrid 3369A, the Bolivian race Pororo and the Equadorian race Chococenõl were all found to proliferate in culture through an aberrant root-like mechanism of growth which had the external appearance of callus. Two related species, teosinte (Zea mexicana Reeves and Mangelsdorf) and tripsacum (Tripsacum dactyloides L.), were less successful in culture, but grew in the same way. Oats, and probably Pororo and Chococeño, initiated presumptive shoot meristems directly from root vascular tissues within this root-like growth. Hybrid maize and wheat initiated no shoot meristems and produced only roots. The occasional shoot production observed in wheat was discounted as simple carryover of existing shoot apices from the primary embryo cultures. This study suggests that the incidence of shoot regeneration in cultures of these cereals may be related more directly to adventitious bud formation on roots than to any controlled de novo organogenesis from undifferentiated callus.

Electronic Resource

1522-9602

Springer Online Journal Archives 1860-2000

Biology

Mathematics

Abstract An accurate approximation is derived to the distribution of the length of the longest matching word present between two random DNA sequences of finite length, using only elementary probability arguments. The distribution is shown to be consistent with previous asymptotic results for the mean and variance of longest common words. The application of the distribution to assessing the statistical significance of sequence similarities is considered. It is shown how the distribution can be modified to take account of non-independence of neighbouring bases in real sequences.

Electronic Resource

0092-8240

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Mathematics

Electronic Resource

0092-8240

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Mathematics

Electronic Resource

0958-0433

Art History

CORRESPONDENCE

1432-0894

Springer Online Journal Archives 1860-2000

Geosciences

Physics

Abstract Pollen, diatom and chironomid fossils from the sediments of a core from Brier Island Bog Lake, Nova Scotia were studied in an attempt to relate changes in microfossil composition to a climatic cooling in Atlantic Canada correlative with the European Younger Dryas ca. 10 to 11 ka. Our paleolimnological data were then compared to similar types of data from Splan Pond, New Brunswick to determine if there were any significant differences between a coastal and a more inland site. Nonarboreal pollen was dominant throughout the Brier Island core and the interval 10.0–11.0 ka did not show the typical decline in Picea and increases in tundra-like vegetation characteristic of many sites in Atlantic Canada. However, the limnological indicators did undergo marked changes in taxon composition. The chironomid assemblage was initially dominated by shallow-water, warm-adapted chironomid taxa followed by abundant Sergentia (a cold stenotherm) during 10–11 ka. Sergentia disappeared in the “post Younger Dryas” interval and the warm-adapted genera resumed dominance. Chironomid-inferred paleotemperature reconstructions revealed that at both Brier Island Bog Lake and Splan Pond, summer surface-water temperatures dropped abruptly to between 13 and 17°C during the 10–11 ka interval, suggesting that a cooler climate was present in Atlantic Canada correlative with the European Younger Dryas. Diatom assemblage changes during the same period corroborate the occurrence of limnological fluctuations.

Electronic Resource

1432-203X

Springer Online Journal Archives 1860-2000

Biology

Abstract Callus derived from stem segments of loblolly pine (Pinus taeda L.) was subcultured to media containing 0.5% of various mono-, di-, tri- or polysaccharides. None of the carbohydrate sources tested were superior to sucrose. Growth on twelve of the 20 carbohydrates tested was more than 75% of that obtained for sucrose; growth on two other carbohydrates became 〉75% of the value for sucrose by the second interval on the new carbon source. Ribose and galactose-containing sugars are among those which support pine callus growth. Dramatic differences in ribose utilization are noted on media supplemented with glutamine vs. NH4/NO3 nitrogen sources.

Electronic Resource

1432-2048

Anther culture ; Embryogenesis (pollen) ; Nicotiana ; Pollen (embryogenesis)

Springer Online Journal Archives 1860-2000

Biology

Abstract The numbers of embryogenic (S) grains present in in-situ mature anthers of Nicotiana tabacum L. were compared to the numbers of embryos and plantlets produced in cultured anthers excised at the optimal mitotic stage of development for anther culture. The Feulgen technique of staining embryos caused a considerable loss of grains from cultured anthers but this did not seriously affect the determination of the percentage of embryos present. In no instance did the numbers of embryos produced exceed the maximum number of S grains found, and the distributions of S grain and embryo frequencies in anthers were similar. In rare instances S grains which had undergone the first embryogenic division were observed in situ. The results indicate that all grains capable of embryogenesis are determined during early flower formation and that their number is not increased by in vitro culture.

Electronic Resource

1432-203X

Springer Online Journal Archives 1860-2000

Biology

Abstract Ploidy levels were calculated for callus cultures of loblolly pine (Pinus taeda L.), based on nuclear DNA content measured by Feulgen cytophotometry. The nuclear DNA content of initial stem explants showed a predominant 2C condition with less 3C and 4C, in ratios approximating those expected from diploid cells as they replicate DNA in the mitotic cell cycle. Cells with higher ploidy were produced during callus initiation, as indicated by a sharp reduction in the 2C population and a concomitant increase in higher DNA levels up to 8C. A gradual decrease in the higher ploidy levels occurred in subsequent subculture intervals, so that by 18 weeks the diploid nuclear DNA distribution was again observed, with complete elimination of DNA levels greater than 4C. Established callus cultures derived from stem or embryo explants and cultured on three different nutrient media for 48–76 weeks also showed the diploid nuclear DNA distribution with no indication of polyploid cells.

Electronic Resource

1432-2048

Springer Online Journal Archives 1860-2000

Biology

Summary Earlier papers of this series relate to different growth-promoting substances and systems which, singly and in combination, have interacted with trace elements (Mn and Mo) and Fe to induce growth and to affect the metabolism of aseptic cultures of carrot. The solutes of cultured carrot cells (K+, Na+, Cl−, total solutes) are also affected. Two clones were grown in 9 combinations of growth factors and under 4 trace-element regimes (a complete complement including Fe, and this complement lacking either Mn or Mo, or both Mn and Mo), a total of 36 treatments under otherwise standardized experimental conditions. Under the treatments applied the number of cells varied over a 35fold range and their average size over a 7fold range; the concomitant effects on their solutes are expressed in terms of concentrations and of total content per cell. Both growth and the solutes accumulated were variously affected by carrot growth-promoting system I (mediated by inositol), by system II (mediated by IAA), and by coconut milk in the presence of Fe, with and without Mn, Mo, or Mn and Mo. The greatest concentrations of total solutes occurred in tissue cultured in nutrient solutions which lacked the stimuli to rapid cell multiplication and were also limited by the trace elements Mn and Mo. Moreover, specific regulatory effects of the trace elements on solute content, not solely attributable to their effects on cell growth, have been noted. An imbalanced growth-factor regime (zeatin acting alone, i.e. without IAA) shifted the normal preference for K+ over Na+ strongly toward Na+, a trend which could also be induced by certain trace elements and more balanced growth-factor regimes, e.g. in a basal coconut milk medium lacking only Mn. The data are interpreted in the context of views on the de-novo uptake of salts and solutes in cultured cells as they grow. These cells respond to a network, or matrix, of interacting factors by distinctive effects that are attributable to the component parts of the culture medium acting singly and in various combinations. These interactions (involving trace elements and exogenous growth factors) control growth (fresh weight, number and size of cells) and regulate the solutes (organic and inorganic; K+ vs. Na+; organic anions vs. Cl−) which the cells acquire as they grow and develop. The intensity of the response of the cultures to balanced, or imbalanced, growth factors creates the internal spaces accessible to solutes; and the metabolism, as it is also affected by growth factors and trace elements, determines how these spaces are to be filled at a given osmotic value. The evidence shows the range of factors that affect the accumulation of solutes in cells as they grow and is to be contrasted with conventional observations on mature cells held in steady states under conditions that preclude all growth and when only a single ionic species is followed over a very short interval of time.

Electronic Resource

1618-2650

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Electronic Resource