The in vitro propagation of amaryllis (Hippeastrum spp. Hybrids)

Summary A new, rapid technique for the propagation of amaryllis (Hippeastrum spp. hybrids) by means of tissue culture is reported. Leaf bases, scapes, peduncles, inner bulb scales and ovaries were cultured successfully in vitro and plantlets were induced readily at various concentrations of growth regulators. Some plantlets also were produced in the absence of growth regulators. The most productive tissues for propagation were inverted scapes and peduncles, cultured in a modified Murashige and Skoog salt solution with added organic constituents and 1 mg per 1 (4.5μM) 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 mg per 1 (4.4μM) 6-benzylaminopurine (BAP). Plantlets induced axenically also grew roots on the generalized shoot-inducing medium so that no special rooting medium was required. Although friable callus was obtained from ovary tissue cultured on a medium containing 2 mg per 1 (11μM) naphthaleneacetic acid and 4 mg per 1 (18μM) BAP, it produced shoots after 8 weeks of further subculture on the same medium. An average of 10 rooted plantlets was obtained from each scape or peduncle explant on the shoot-propagating medium. Thus, if 45 explants are obtained from each bulb, 450 rudimentary plantlets could be obtained from each mother bulb in 8 weeks of culture. This is a substantial increase over present propagation methods. This work was supported by a grant-in-aid of research, to Bruce G. Cumming, from the National Research Council of Canada.     

Genetic distinctness of three widespread and morphologically variable species of Drupella (Gastropoda,Muricidae)

Corallivorous gastropods of the genus Drupella have caused considerable damage to corals at widely separated reefs in the Indo-Pacific. Morphological variability of Drupella species within and between areas has caused taxonomic confusion. To clarify the relationships, we examined allozyme variation at 16 gene loci in samples from Western Australia, Queensland and Japan. Within sites, the species D. cornus, D. rugosa and D. fragum were distinguishable individually by each of 9 to 11 loci, with average genetic identities of about 0.25. The differences extended across sites, whereas the conspecific genetic identities over distances up to 6000 km were 0.86 to 1.00, supporting the view that there are three widespread species of Drupella. Nevertheless, there is much variation within species for allozymes, size, shape and colour.     

Axonal sub-populations in the central nervous system demonstrated using monoclonal antibodies against alpha-tubulin

Using two monoclonal antibodies that specifically recognise alpha-tubulin we describe differences in their light and electron microscopic immunoperoxidase staining of axons in cerebellum, hippocampus, and cerebral cortex. In the molecular layer of the cerebellar cortex at the light microscopic level, one of the antibodies (YOL/34) labelled parallel fibre axons (in an identical manner to a beta-tubulin monoclonal antibody) while the other antibody (YL1/2) failed to label them. Extending these studies to the electron microscopic level in the cerebellum we have determined the sub-cellular localisation of alpha-tubulin in microtubules and the postsynaptic density, and also demonstrated a sub-population of parallel fibres and myelinated axons labelled with antibody YL1/2. The monoclonal antibodies were further characterised using immunoblotting against alpha-tubulin separated by isoelectric focusing gels. The results suggest that the contrasting staining patterns between the alpha-tubulin antibodies may reflect axonal sub-populations containing different isotypes of alpha-tubulin.