Isolation of amyloplasts from developing maize endosperm

Methods for the formation of protoplasts from developing maize endosperm and for the aqueous isolation of intact amyloplasts from such protoplasts are described. Protoplasts were obtained after incubating endosperm slices in a medium containing cellulase and pectolyase for 5 days at 4 degrees C or 5 hours at 30 degrees C. After purification in a Ficoll density gradient, the protoplasts were reptured by forcing the suspension through a Nitex mesh (20 micrometer) positioned at the lower end of a modified disposable syringe. The resulting filtrate was layered on a discontinuous Ficoll density gradient of 30, 15, and 10%. Each Ficoll solution contained 0.7 molar sucrose, 10 millimolar arginine, 10 millimolar dl-dithiothreitol, 50 millimolar 2-(N-morpholino)ethanesulfonic acid (pH 5.6), and 2 millimolar CaCl(2). After 3 hours in the cold, an amyloplast fraction 50 to 93% intact and free from cytoplasmic, mitochondrial, and glyoxysomal contamination was recovered in the 15% Ficoll layer. Amyloplast intactness was estimated by fluorescent microscopy and activity of certain amyloplast marker enzymes before and after rupture of the amyloplast membrane. Starch branching enzyme, ADPG-pyrophosphorylase, and nitrite reductase were used as amyloplast marker enzymes.

Malaria in southeast Queensland in 1979

The incidence of malaria in Australia is increasing. With the emergence of strains of Plasmodium falciparum resistant to chloroquine there are new lessons to be learned by laboratory workers in the species diagnosis; by clinicians in the clinical manifestations, the treatment of prophylaxis; and by members of the public about the dangers of malaria, and how it can be prevented. At the same time, old knowledge must not be forgotten. This paper reports some recent experience with a sizeable number of cases.

Atherosclerotic coarctation of the abdominal aorta in women

In the ten year interval from 1967 to 1976, in a group of 200 patients with aortoiliac occlusive disease, six were identified who presented a unique combination of physical findings, angiographic abnormalities and pathologic changes. Atherosclerotic coarctation describes this entity because of the discreteness of the lesion found, the extent to which the aorta is occluded and the presence of extensive collaterals. Pathologically, the lesion is an organized thrombus forming on a single ulcerated plaque in an aorta with a lumen that is otherwise well preserved. Distally, infantile vessels are found. Other features have been the absence of diabetes mellitus and the fact that all of these patients have been women. All but one patient smoked cigarettes. Local endarterectomy restored pedal pulses and provided lasting relief of symptoms in all of the patients.