The behaviour of normal and agravitropic transgenic roots of rapeseed (Brassica napus L.) under microgravity conditions

In the TRANSFORM experiment for IML-2 on the Space Shuttle Columbia, normal (wild type = WT) and genetically transformed agravitropic rapeseed roots were tested under microgravity conditions. The aim of the experiment was to determine if the wild-type roots behaved differently (growth, morphology, gravitropical sensitivity) from the transgenic roots. The appearance of the organelles and distribution of statoliths (i.e. amyloplasts with starch grains) in the gravitropic reactive cells (statocytes) under weightlessness was compared for the two types of roots. Attempts have also been made to regenerate new plants from the root material tested in space. Both the WT and the transgenic root types showed the expected increase in length during 36 h of photorecording. Contrary to the results of the ground controls, no significant difference in elongation rates was found between the WT and transgenic roots grown in orbit. However, there are indications that the total growth both in the WT and the transgenic roots was higher in the ground control than for roots in orbit. After a 60 min 1 x g stimulation of the roots on board the Shuttle, no detectable curvatures were obtained in either the transgenic or the WT roots. However, it cannot be excluded that a minute curvature development occurs in the root tips but was not detected due to technical reasons. The ultrastructure was well preserved in both the WT and the transgenic roots, despite the fact that the tissue was kept in the prefixative for over 3 weeks. No marked differences in ultrastructure were observed between the transformed root statocyte cells and the equivalent cells in the wild type. There were no obvious differences in root morphology during the orbital period. Light micrographs and morphometrical analysis indicate that the amyloplasts of both the wild type and transformed root statocytes are randomly distributed over the cells kept under micro-g conditions for 37 h after a 14 h stimulation on the 1 x g centrifuge. The main scientific conclusion from the TRANSFORM experiment is that the difference in growth found in the ground control between the WT and the transgenic root types seems to be eliminated under weightlessness. Explanations for this behaviour cannot be found in the root ultrastructure or in root morphology.     

Candida biotypes in patients with oral leukoplakia and lichen planus

Prevalence of yeasts in 35 leukoplakia and 34 oral lichen planus patients was compared with that observed in persons without oral diseases. Serotype and morphotype were determined on Candida albicans isolates. Yeasts were isolated from the oral cavity specimens of 43.7% of the patients. C. albicans (serotype A) was the predominant species (76% in leukoplakia, 88.2% in lichen planus and 60.8% in healthy persons). Sixteen morphotypes were encountered on malt extract agar, being 732, 733, 734, 753 and 754 the most frequently found. Morphotypes SP1N and SP1Y were the most common on Sabouraud-trypheniltetrazolium agar (68.4% of the isolates from leukoplakia and 73.3% from lichen planus, but only 46.6% of the isolates from healthy oral mucosa showed SP1N morphotype). Presence of oral lesions was associated with a marked reduction in the yeast species and C. albicans biotypes, suggesting that C. albicans and particularly some of its biotypes, show a high potential of adaptation to the changes associated with the development of oral leukoplakia and lichen planus.     

Somatic mosaicism in a patient with neurofibromatosis type 1.

Using loss of heterozygosity analysis, a method designed to detect moderate to large gene deletions, we have identified a new-mutation neurofibromatosis type 1 (NF1) patient who is somatically mosaic for a large maternally derived deletion in the NF1 gene region. The deletion extends at least from exon 4 near the 5' end of the gene to intron 39 near the 3' end. The gene-coding region is, therefore, mostly or entirely deleted, encompassing a loss of > or = 100 kb. We hypothesize that the deletion occurred at a relatively early developmental timepoint, since signs of NF1 in this patient are not confined to a specific body region, as seen in "segmental" NF, and since both mesodermally and ectodermally derived cells are affected. This report provides the first molecular evidence of somatic mosaicism in NF1 and, taken together with a recent report of germ-line mosaicism in NF1, adds credence to the concept that mosaicism plays an important role in phenotypic and genetic aspects of NF1 and may even be a relatively common phenomenon.     

Whisker-mediated plant transformation: An alternative technology

A number of different methods, involving direct DNA delivery are now available for plant transformation. Here we review the most recently developed technique which involves the mixing of silicon carbide whiskers with plant cells and plasmid DNA. Fertile transgenic plants have now been produced using whisker-mediated transformation, and this method can now be considered as a simple, inexpensive alternative for plant transformation. A brief review on transformation of animal cells andChlamydomonas using whiskers technology is also included.     

The calmodulin-dependent protein phosphatase catalytic subunit (calcineurin A) is an essential gene in Aspergillus nidulans.

The gene encoding the homologue of the catalytic subunit of the Ca2+/calmodulin-regulated protein phosphatase 2B (calcineurin A) has been isolated from Aspergillus nidulans. This gene, cnaA+, is essential in this fungal system. Analysis of growth-arrested cells following gene disruption by homologous recombination reveals that they are blocked early in the cell cycle. The cnaA+ gene encodes a 2.5 kb mRNA and the deduced protein sequence is highly homologous to the calcineurin A subunit of other species. The mRNA varies in a cell cycle-dependent manner with maximal levels found early in G1 and considerably before the G1/S boundary. As calmodulin is also essential for A.nidulans cell cycle progression and levels rise before the G1/S boundary, our data suggest that calcineurin may represent a primary target for calmodulin at this cell cycle transition point.     

The calmodulin-dependent protein phosphatase catalytic subunit (calcineurin A) is an essential gene in Aspergillus nidulans.

The gene encoding the homologue of the catalytic subunit of the Ca2+/calmodulin-regulated protein phosphatase 2B (calcineurin A) has been isolated from Aspergillus nidulans. This gene, cnaA+, is essential in this fungal system. Analysis of growth-arrested cells following gene disruption by homologous recombination reveals that they are blocked early in the cell cycle. The cnaA+ gene encodes a 2.5 kb mRNA and the deduced protein sequence is highly homologous to the calcineurin A subunit of other species. The mRNA varies in a cell cycle-dependent manner with maximal levels found early in G1 and considerably before the G1/S boundary. As calmodulin is also essential for A. nidulans cell cycle progression and levels rise before the G1/S boundary, our data suggest that calcineurin may represent a primary target for calmodulin at this cell cycle transition point.     

Advance directives, autonomy and unintended death

This Paper argues that Living wills are typically nebulous and confused documents that do not effectively enable you to determine your future treatment. Worse, signing a living will can end your life in ways you never intended, long before you are either incompetent or terminally ill. This danger is compounded by the fact that those who implement living wills are often themselves dangerously confused, so that, for example, they cannot be relied upon to distinguish living wills from DNR orders. In addition, the Paper argues that advance directives concerning resuscitation are often so confused that they end the lives of healthy, alert people who have not suffered cardiac or pulmonary arrest. Finally, the paper argues that advance directives establishing durable power of attorney for health care often preserve the chief dangers of living wills. Suggestions are offered as to how you can most effectively direct your future treatment without endangering your life.     

Elemental microanalysis of fibroblasts by a scanning proton microprobe and application to Menkes’ disease

A scanning proton microprobe has been used for the elemental microanalysis of individual fibroblast cells. Both normal fibroblasts and fibroblasts cultured from patients with Menkes' disease, an X-linked genetic disorder known to be associated with defective copper metabolism, were examined by the probe. The cells were cultured on a thin ultra-clean nylon foil and retained on that surface for analysis. The focused high-energy proton beam was used to irradiate selected individual cells and elemental information was derived from X-ray and backscattered proton data. The sensitivity of the scanning proton microprobe to trace concentrations of heavy elements has allowed this elemental information to be used to identify individual cells as being either normal or a Menkes' mutant. The cell identification was based on the application of discriminate analysis to a data set formed from the ratios of copper to each of the macroelements present in the cell. This method of cell identification offers the promise of rapid diagnosis of Menkes' disease.