Developmental Changes of Etioplasts in Isolated Suspensions and in situ

A simple model and procedure for assessing the ultrastructuraldevelopment and the degree of desynchronization of a populationof etioplasts is used to illustrate the effect of an improvedmedium for the incubation of suspensions of etioplasts. Themethod also enables an assessment of ultrastructural developmenttaking place in these plastids to be compared with that takingplace within intact tissue over a similar period of time. Forthe first 1–2 h of incubation, the degree of developmentalmost parallels that taking place in vivo; thereafter, developmentwithin suspensions of plastids is slowed down. Similar inversechanges are recorded with respect to the degree of desynchronizationof the plastid populations. Inhibitors are used to identifycritical stages of chloroplast development and the nature ofextra-chloroplastic involvement in the development of plastids,which is evident from these combined experiments, is discussed.     

DNA Fingerprinting of Trypanosoma vivax Isolates Rapidly Identifies Intraspecific Relationships

ABSTRACT. Using the polymerase chain reaction and arbitrarily selected oligonucleotide primers of 10 or 11 bases, we have amplified DNA sequences from Trypanosoma vivax parasites isolated from South America and Africa. On the basis of polymorphisms in the DNA fingerprints generated by three of the primers, the parasites could be separated into two major groups, one comprising T. vivax isolates from Kenya and the second including all the other T. vivax parasites (from Colombia, The Gambia, Nigeria and Uganda). One of these three primers (ILo 525) also gave isolate-specific DNA fingerprints for the parasites for the parasites tested, which will allow the use of this technique both in the species identification and discrimination of T. vivax parasites.