Pathological and serological evidence and DNA-DNA reassociation data indicate that Chlamydophila psittaci and Chlamydophila abortus are separate species. C. psittaci causes avian systemic disease and C. abortus causes abortion. Both previously belonged to Chlamydia psittaci are associated with zoonotic and enzootic outbreaks. Genetic studies suggest that they are closely related and because of the recent availability of diverse C. psittaci strains and comparative data for several genes, it was possible to explore this relationship. The parrot C. psittaci strain 84/2334 was found to have DNA sequences that were identical to an extrachromosomal plasmid in duck C. psittaci strain N352, to rnpB in strain R54 from a brown skua and to the rrn intergenic spacer in parakeet strain Prk/Daruma (from Germany, Antarctica and Japan, respectively). Analysis of ompA and the rrn spacer revealed progressive diversification of the strains, with 84/2334 resembling what might have been a recent ancestor of C. abortus. Another C. psittaci strain (VS225) showed evidence of having undergone convergent evolution towards the C. abortus-like genotype, whereas strain R54 diverged independently. For the first time, these studies link C. abortus in an evolutionary context to the C. psittaci lineage. It has been concluded that C. abortus diverged from C. psittaci, and so strain R54 was designated a C. psittaci strain. It is recommended that characterization of C. psittaci and C. abortus strains should utilize more than a single method and more than a single gene. INTRODUCTIONChlamydophila psittaci is a lethal intracellular bacterial species that causes avian chlamydiosis, epizootic outbreaks in mammals and respiratory psittacosis in humans (Durfee et al., 1975;Anderson et al., 1978;Edwards, 1981;Hedberg et al., 1989;Ni et al., 1996;Brewis & McFerran, 1997;Goupil et al., 1998;Bennedsen & Filskov, 2000; Centers for Disease Control and Prevention, 2000). Chlamydophila abortus causes abortion and foetal death in mammals, including humans (Wong et al., 1985;Jorgensen, 1997;Rodolakis et al., 1998). In the absence of sequence data, these species have no apparent relationship. Side-by-side comparisons of C. psittaci and C. abortus in birds and other animals show differences in infectivity, persistence, disease and seroconversion (Page, 1966;Johnson & Grimes, 1983;Tappe et al., 1989). Different mAbs recognize C. psittaci and C. abortus (Perez-Martinez & Storz, 1985;Eb et al., 1986;Fukushi et al., 1987;Takahashi et al., 1988;Andersen & Van Deusen, 1988; Kikuta et al., 1991;Andersen, 1991;Vretou et al., 1996). C. psittaci and C. abortus genomes exhibit different restriction endonuclease patterns (Herring et al., 1987;Timms et al., 1988;McClenaghan et al., 1991; Sayada et al., 1995). DNA-DNA reassociation studies show that C. psittaci and C. abortus are 27-85 % similar (Cox et al., 1988;Fukushi & Hirai, 1989). C. psittaci strains more often than not have an extrachromosomal plasmid, while C. abortus strains have no plasmid . The genetic criteria respo...

Thirty-three isolates of Colletotrichum gloeosporioides from various Stylosanthes species collected in Africa and Australia and associated with restricted (type A), extensive (type B) or nontypical anthracnose lesions (type C) were first compared by random amplified polymorphic DNA (RAPD) analysis. A phylogenetic tree was constructed based on 118 reproducible polymorphic bands generated with 16 random primers, using the upgma method. Twenty-nine isolates were grouped in two main clusters, corresponding to types A and B, within which polymorphic subgroups were partially related to geographical origin. Strong similarities were observed among isolates of distant origin. Four isolates presented profiles completely different from the A and B types and were grouped in two additional clusters. To assess the phylogenetic relationship among isolates of various types and origins at the species level, the lnternal Transcribed Spacer region (ITS 1) of the ribosomal DNA was sequenced. Type A isolates and a restricted number of type B isolates selected in the RAPD clusters showed an homology of 99·4-100%. When compared with published sequence data, the isolates that were clustered separately in the phylogenetic tree, had the exact sequence of a C. gloeosporioides strain associated with the rotting of coffee berries, or of C. kahawae, the causal agent of coffee berry disease.

To reveal the chromosomal location of three known low-molecular-weight (LMW) glutenin genes in wheat, we designed and used three sets of sequence-specific primers in polymerase chain reactions (PCR) on 'Chinese Spring' and its derived group 1 aneuploid nullisomic-tetrasomic stocks. Two sets proved to be chromosome specific and amplified sequences from the Glu-A3 and Glu-D3 loci, respectively. The third set was apparently composed of conserved sequences as it produced PCR products in each of the aneuploids. Two of these products were cloned, and their sequences differed from the known LMW glutenin genes at several positions. Again, primer sets specific for these sequences were designed. One set was directed to the Glu-A3 locus, the second set resulted in two PCR products differing in length, one of which was located on chromosome 1B and the other on 1D. Primer sets constructed for the latter two sequences were specific for the Glu-B3 and Glu-D3 loci, respectively. Hence, primer sets specific for each of the three homoeologous chromosomes of the group 1 (1A, 1B, 1D) are available. In addition, these locus-specific primers were assayed for their ability to distinguish among wheat cultivars. PCR products amplified with one of the Glu-A3-specific primer sets showed length polymorphisms in various wheat varieties. Varieties carrying the 1RS.1BL translocated chromosomes could be recognized by the absence of a PCR product when the Glu-B3 primer set was used. These results suggest that PCR with locus-specific primers can be useful in the molecular genetic analysis of hexaploid wheat.

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