Changes in genome structure and gene expression have been documented in both resynthesized and natural allopolyploids that contain two or more divergent genomes. The underlying mechanisms for rapid and stochastic changes in gene expression are unknown. Arabidopsis suecica is a natural allotetraploid derived from the extant A. thaliana and A. arenosa genomes that are homeologous in the allotetra...

ODC 232.315 015.28 The ultrastructure of three parts (endos.vernz, rootlets and cotyledorrs) of aged seeds o f Pinus sylvestris L. has been studied. In dry seeds no clear differences resulting from ageing are seen as compared with resting living cells, but during imbibition clear differences are evident. Inhibition of development of the D N A containing structures, mitochondria and plastids, wa...

abstract this study was performed to compare the efficiency of 6 microalgae namely dunaliella tertiolecta, tetraselmis suecica, chlorella sp., (green algae), nannochloropsis oculata, spirolina sp.(blue-green algae) cheatocerus sp. (diatoma),  and isochrices sp. (haptophytae) on the growth, survival and reproduction efficacy in artemia urmiana in laboratory conditions. artemia cysts were harvest...

Nucleolar dominance is a widespread epigenetic phenomenon, describing the preferential silencing of ribosomal RNA (rRNA) genes inherited from one progenitor of an interspecific hybrid, independent of maternal or paternal effects. In the allotetraploid hybrid plant species Arabidopsis suecica, A. thaliana-derived rRNA genes are silenced whereas the A. arenosa-derived rRNA genes are transcribed. ...

Polyploidy is an example of instantaneous speciation when it involves the formation of a new cytotype that is incompatible with the parental species. Because new polyploid individuals are likely to be rare, establishment of a new species is unlikely unless polyploids are able to reproduce through self-fertilization (selfing), or asexually. Conversely, selfing (or asexuality) makes it possible f...

Ms received 1976-05-05 LiberForlag/Allmanna Forlaget ISBN 91-38-03190-6. lSSN 0039-3150 Berlingska Boktrpckeriet. Lund 1976

ODC-844.2 The ability o f the soft rot fungus Humicola alopallonella Meyers & Moore to form cavities in various cellulose fibres has been studied. The following fibre materials were tested: wood of aspen, beech, birch, pine and spruce, three sulphate pulps with different lignin content, spruce holocellulose, Avicel, Sigmacell T38, flax, jute, ramie, sisal, cotton, kapok, seed hairs o f Salix pe...

ODC 164.5: 174.7 Pinus sylvestris + I68 164.5 T h e ultra.structure of the different cell types in mature needles o f pine (Pinus silvestris L.) is described. The epidermal cells are protoplasma-free with prominent secondary a~alls. The sunken guard cells have chloroplasts o f a simple structure and many mitochondria. A hypodermal layer is formed by living vacuolated fiber cells. The mesophyll ...

Thirty-six species o f wood-inhabiting microfungi have been assayed for cellulase, xylanase, mannanase and amylase activity by the use o f different test methods. The wood-degrading capabilities of the test organisms were previously known. Three o f the species were unable t o degrade birch wood. The other species represented three different degradation patterns, viz. I ) formation of soft rot ...

It has been hypothesized that polyploidy permits the proliferation of transposable elements, due to both the masking of deleterious recessive mutations and the breakdown of host silencing mechanisms. We investigated the patterns of insertion polymorphism of an Ac-like transposable element and nucleotide diversity at 18 gene fragments in the allotetraploid Arabidopsis suecica and the autotetrapl...