We have assayed genetic polymorphisms in several species of parasitic protozoa by means of random amplified polymorphic DNA (RAPD). One goal was to ascertain the suitability of RAPD markers for investigating genetic and evolutionary problems, particularly in organisms, such as the parasitic protozoa, unsuitable for traditional methods of genetic analysis. Another goal was to test certain hypotheses concerning Trypanosoma cruzi, and other protozoa, that have been established by multilocus enzyme electrophoresis. The RAPD results corroborate the hypothesis that the population structure of T. cruzi is clonal and yield a phylogeny of the clonal lineages in agreement with the one obtained by enzyme electrophoresis. This parity between the two sets ofresults confirms that RAPD markers are reliable genetic markers. The RAPD markers are also suitable for reconstructing species phylogenies and as diagnostic characters of species and subspecific lineages. The number of DNA polymorphisms that can be detected by the RAPD method seems virtually unlimited, since the number of primers can be increased effectively at will. The RAPD method is well suited for investigating genetic and evolutionary questions in certain organisms, because it is cost effective and demands no previous genetic knowledge about the organism.The recently developed technique of random amplified polymorphic DNA (RAPD) provides an effective method for obtaining genetic markers in all sorts of organisms (1-4). The RAPD method identifies polymorphisms that are detected as DNA fragments, amplified by the Taq polymerase chain reaction (PCR), that are present in one but not another individual or strain. Short oligonucleotides (about lO-mer) of arbitrary nucleotide sequence are often used as amplifying primers, although nonrandom longer primers have proved useful for certain purposes (4).The RAPD method holds considerable promise for population genetic and evolutionary studies (5) because (i) no previous sequence information is needed in the target organism and hence all sorts of organisms are accessible, (ii) many markers can readily be identified, as is required for the reconstruction ofphylogenetic history, and (iii) the effort and cost involved are modest so that many individuals can be assayed, which is usually necessary for investigating population genetic problems.The validity of the method in broad practice remains, however, to be established. Questions arise as to the consistency of the results, the genetic significance of the amplified DNA sequences, and even the possibility of artifactual outcomes (6). In situations where genetic crosses are not possible, either because the organisms belong to different species or because sexual reproduction is absent (or not feasible experimentally), these issues cannot be resolved by traditional Mendelian methods; they can be investigated only by indirect methods.We summarize a RAPD study of several parasitic protozoa. The results are consistent with data previously obtained by multilocus enzyme electrophores...

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SummaryThe production of biodegradable polymers that can be used to substitute petrochemical compounds in commercial products in transgenic plants is an important challenge for plant biotechnology. Nevertheless, it is often accompanied by reduced plant fitness. To decrease the phenotypic abnormalities of the sprout and to increase polymer production, we restricted cyanophycin accumulation to the potato tubers by using the cyanophycin synthetase gene (cphA Te ) from Thermosynechococcus elongatus BP-1, which is under the control of the tuber-specific class 1 promoter (B33).Tuber-specific cytosolic (pB33-cphA Te ) as well as tuber-specific plastidic (pB33-PsbYcphA Te ) expression resulted in significant polymer accumulation solely in the tubers.In plants transformed with pB33-cphA Te , both cyanophycin synthetase and cyanophycin were detected in the cytoplasm leading to an increase up to 2.3% cyanophycin of dry weight and resulting in small and deformed tubers. In B33-PsbY-cphA Te tubers, cyanophycin synthetase and cyanophycin were exclusively found in amyloplasts leading to a cyanophycin accumulation up to 7.5% of dry weight. These tubers were normal in size, some clones showed reduced tuber yield and sometimes exhibited brown sunken staining starting at tubers navel. During a storage period over of 32 weeks of one selected clone, the cyanophycin content was stable in B33-PsbYcphA Te tubers but the stress symptoms increased. However, all tubers were able to germinate. Nitrogen fertilization in the greenhouse led not to an increased cyanophycin yield, slightly reduced protein content, decreased starch content, and changes in the amounts of bound and free arginine and aspartate, as compared with control tubers were observed.

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