Epstein-Barr virus (EBV), a ubiquitous human herpesvirus and an aetiological agent of infectious mononucleosis, has a unique tropism for B lymphocytes. Clinical and laboratory features of chronic active EBV infections are chronic or persistent infectious mononucleosis-like symptoms and high antibody titre against early antigens (EA). Kawasaki disease (KD), aetiology unknown, is thought to be self-limited immunologically mediated vasculitis. Clinical features of KD are fever, rash, mucositis, lymphadenopathy and coronary artery damage. We report here a child with chronic active EBV infection accompanied by dilatation of coronary arteries. All the EBV-determined nuclear antigen (EBNA)-positive lymphocytes had exclusively CD4 antigen, as revealed by dual staining immunofluorescence analysis. Southern blot hybridization showed that the purified CD4+ cells harboured EBV genome.

We have cloned and sequenced the cytochrome oxidase subunit II (coxII) gene from both normal and cytoplasmic male-sterile (CMS) sugar beet. The normal coxII (designated NcoxII) locus was found to be located 1491 bp upstream from the gene for cytochrome oxidase subunit I (coxI) on the same DNA strand and to have a 1463 bp intron which split the coding sequence into two exons (382 and 398 bp). The COXII protein contains 260 amino acid residues. We have also found two copies of the coxII gene (ScoxII-1 and ScoxII-2) to be present in the CMS genome. Our results suggest that the NcoxII gene diverges completely from the ScoxII-1 and ScoxII-2 genes 50 bp 5' to the ATG start codon. In addition, the ScoxII-1 and ScoxII-2 sequences could be readily discriminated from each other by the 3' end and the immediately adjacent flanking sequences of the gene: the 3' divergence results in a 101 codon extension of the ScoxII-2 ORF. Northern blot analysis demonstrates that the coxII gene exhibits altered transcript patterns in CMS compared with normal sugar beet. Different genomic arrangements of the coxII gene are considered to be the result of extensive intra- and inter-molecular recombination events involving the repeated DNA elements in the mitochondrial genome.

We have characterized the mitochondrial atpA (the alpha subunit of F1-ATPase) gene from male-fertile cytoplasm (cv TK81-0) of sugar beet. The gene is 1518-bp long and encodes a polypeptide of 506 amino acids. The atpA mRNA sequence is modified by three C-to-U RNA editing events, all of which alter the encoded protein sequences. In order to examine the genome organization of the atpA locus in cytoplasmic male-sterile (CMS) sugar beet, atpA-containing clones were isolated from Owen CMS (TK81-MS) and a different source of CMS [I-12CMS(2)] cytoplasm respectively. The sequences of the atpA coding region from TK81-MS and I-12CMS(2) are identical to each other and to the corresponding TK81-0 sequence. However, the TK81-0 and TK81-MS loci diverge completely 47 bp upstream of the initiation codon, resulting in different 5' transcript termini for the two genes. On the other hand, the point of divergence between the TK81-0 and I-12CMS(2) atpA genes was found to occur after 393 bp 3' to the TAA stop codon. Our results also show the 3'-flanking sequences of I-12CMS(2) atpA to be present elsewhere in the mitochondrial genomes of TK81-0, TK81-MS and I-12CMS(2), suggesting the possible involvement of these repeated DNA elements in the sequence rearrangements.

To increase the available set of near-isogenic lines (NILs) for blast-resistance in rice, we have developed a general method for establishing NILs from populations of fixed recombinants that have been used for gene mapping. We demonstrated the application of this method by the selection of lines carrying genes from the rice cultivar Moroberekan. Moroberekan is a West African japonica cultivar that is considered to have durable resistance to rice blast. Multiple genes from Moroberekan conferring complete and partial resistance to blast have previously been mapped using a recombinant inbred (RI) population derived from a cross between Moroberekan and the highly and broadly susceptible indica cultivar CO39. To analyze individual blast-resistance genes, it is desirable to transfer them individually into a susceptible genetic background. This RI population, and the associated data sets on blast reaction and restriction fragment length polymorphism (RFLP) genotypes, were used for selection of lines likely to carry individual blast-resistance genes and a minimum number of chromosomal segments from Moroberekan. Because skewed segregation in the RI population favored CO39 (indica) alleles, resistant lines carrying 8.7-17.5% of Moroberekan alleles (the proportion expected after two or three backcrosses) could be selected. We chose three RI lines carrying different complete resistance genes to blast and two RI lines carrying partial resistance genes to blast as potential parents for the development of NILs. These lines were subjected to genetic analysis, which allowed clarification of some issues that could not be resolved during the initial gene-mapping study.

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