Male sterility is of special interest as a mechanism allowing hybrid breeding, especially in important crops such as rapeseed (Brassica napus). Male sterile plants are also suggested to be used as a ...biological safety method to prevent the spread of transgenes, a risk that is high in the case of rapeseed due to the mode of pollination, out-crossing by wind or insects, and the presence of related, cross-pollinating species in the surrounding ecosystem in Europe. Different natural occurring male sterilities and alloplasmic forms have been tried to be used in rapeseed with more or less success. Due to the difficulties and limitations with these systems, we present a biotechnological alternative: a metabolically engineered male sterility caused by interference with anther-specific cell wall-bound invertase. This is an essential enzyme for carbohydrate supply of the symplastically isolated pollen. The activity of this enzyme is reduced either by antisense interference or by expressing an invertase inhibitor under control of the anther-specific promoter of the invertase with the consequence of a strong decrease of pollen germination ability.
Single crystals of Mg32(Al,Zn)49, a complex metallic alloy phase with 162 atoms per unit cell and a lattice parameter of 14.16 A, were grown by means of the Bridgman and the Czochralski technique. We ...are able to produce single crystals of high structural quality with volumes of up to 3 cm3 and a composition of about Mg36Al27Zn37.
Single crystals of Mg
32(Al,Zn)
49, a complex metallic alloy phase with 162 atoms per unit cell and a lattice parameter of 14.16
Å, were grown by means of the Bridgman and the Czochralski technique. ...We are able to produce single crystals of high structural quality with volumes of up to 3
cm
3 and a composition of about Mg
36Al
27Zn
37.
The development of a single-crystal growth route for the complex metallic alloy phase β-Al
3Mg
2 is presented. After initial probing of the phase diagram in the vicinity of the existence range of the ...β-phase, we performed single-crystal growth experiments employing various techniques. The Czochralski and self-flux growth turned out to be the most suitable for this phase, and with both we reproducibly achieved single crystals of several cubic centimeters in volume. While the Czochralski technique allows for the production of deliberately oriented single crystals, the self-flux technique is capable of producing very large but unoriented single grains.
