Aluminium effects on microtubule organization in dividing root-tip cells of Triticum turgidum. I. Mitotic cells

The effects of aluminium (Al) on dividing root-tip cells of Triticum turgidum were investigated with tubulin immunolabelling and electron microscopy. Aluminium affects the mechanisms controlling the organization of microtubule (MT) cytoskeleton, as well as tubulin polymerization, and induces the following aberrations in mitotic cells. (1) It delays the MT disassembly during mitosis, resulting in the persistence of preprophase MT bands in the late prophase cells, the presence of prophase spindles in prometaphase cells, and a disturbance in the shortening of kinetochore MT bundles in anaphase cells. (2) It interferes with the self-organization process of MTs into bipolar systems, inhibiting the formation of prophase and metaphase spindles. (3) Aluminium induces the formation of atypical MT arrays, which in the immunofluorescent specimens appear as ring-like tubulin aggregations in the cortical cytoplasm of the preprophase/prophase cells and as endoplasmic tubulin bundles in prophase and metaphase/anaphase cells; abnormal preprophase MT bands are assembled, consisting of atypical cortical and endoplasmic MT bundles, the latter clearly lining the nuclear envelope on the preprophase MT band plane. (4) It disorders the chromosome movements carried out by the mitotic spindle. In addition, after prolonged Al treatments chromatin condensation is inhibited. The outcome is greatly disturbed organization and function of the mitotic apparatus, as well as inhibition of cells from entering mitosis. This study shows that the MT cytoskeleton is a target site of Al toxicity in mitotic root-tip cells of T. turgidum . The possible mechanisms by which Al exerts its toxicity on MT organization and function are discussed.     

Mitochondrial DNA polymorphisms of the house mouse Mus musculus domesticus from Greece, focusing on the Robertsonian chromosomal system of north-west Peloponnese

This study focused on the sequence variation in a mitochondrial region in house mice Mus musculus domesticus from chromosomally variable populations in the north-west Peloponnese, Greece. The mitochondrial molecular variation revealed was among the highest found so far for M. m. domesticus populations. The haplotype distribution pattern was rather complex. There was no clear differentiation between the populations characterized by Robertsonian chromosomes and standard all-acrocentric populations. There is therefore no indication that the Robertsonian populations were formed during a prolonged period of geographical isolation.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 643–651.     

THE SUSCEPTIBILITY OF POTATO VARIETIES TO INFESTATION BY THE EELWORMS DITYLENCHUS DESTRUCTOR AND D. DIPSACI

Twenty-five varieties of potato in common commercial cultivation were found to be susceptible to tuber attack by potato-derived populations of Ditylenchus destructor under field and pot experimental conditions. Stunting and leaf deformation may also be caused by the eelworms but appear less consistently. A race of D. destructor from mushroom spawn had almost no effect on potatoes. Various races of D. dipsaci can reproduce in the shoot tissue of potato, sometimes causing damage. One population of this stem eelworm produced lesions on the tubers.