Comparison of the genetic determinism of two key phenological traits, flowering and maturity dates, in three Prunus species: peach, apricot and sweet cherry.

The present study investigates the genetic determinism of flowering and maturity dates, two traits highly affected by global climate change. Flowering and maturity dates were evaluated on five progenies from three Prunus species, peach, apricot and sweet cherry, during 3-8 years. Quantitative trait locus (QTL) detection was performed separately for each year and also by integrating data from all years together. High heritability estimates were obtained for flowering and maturity dates. Several QTLs for flowering and maturity dates were highly stable, detected each year of evaluation, suggesting that they were not affected by climatic variations. For flowering date, major QTLs were detected on linkage groups (LG) 4 for apricot and sweet cherry and on LG6 for peach. QTLs were identified on LG2, LG3, LG4 and LG7 for the three species. For maturity date, a major QTL was detected on LG4 in the three species. Using the peach genome sequence data, candidate genes underlying the major QTLs on LG4 and LG6 were investigated and key genes were identified. Our results provide a basis for the identification of genes involved in flowering and maturity dates that could be used to develop cultivar ideotypes adapted to future climatic conditions.

Contrasting relationships between the diversity of candidate genes and variation of bud burst in natural and segregating populations of European oaks.

Nucleotide diversity was assessed within nine candidate genes (CGs) (in total 4.6 kb) for the time of bud burst in nine sessile oak (Quercus petraea) populations distributed in central and northern Europe. The sampled populations were selected on the basis of their contrasting times of bud burst observed in common garden experiments (provenance tests). The CGs were selected according to their expression profiles during the transition from quiescent to developing buds and/or their functional role in model plants. The overall nucleotide diversity was large (pi(tot)=6.15 x 10(-3); pi(silent)=11.2 x 10(-3)), but population differentiation was not larger than for microsatellites. No outlier single-nucleotide polymorphism (SNP) departing from neutral expectation was found among the total of 125 SNPs. These results contrasted markedly with the significant associations that were observed between the CGs and bud burst in segregating populations. Quantitative trait loci (QTLs) for bud burst were identified for 13 year*site seasonal observations in a cloned mapping pedigree. Nineteen QTLs were detected, and QTLs located on linkage groups 2, 5 and 9 contributed repeatedly to more than 12% of the phenotypic variation of the trait. Eight genes were polymorphic in the two parents of the pedigree and could be mapped on the existing genetic map. Five of them located within the confidence intervals of QTLs for bud burst. Interestingly, four of them located within the three QTLs exhibiting the largest contributions to bud burst.

Contrasting relations between diversity of candidate genes and variation of bud burst in natural and segregating populations of European oaks.

Nucleotide diversity was assessed within nine candidate genes (in total 4.6 kb) for the time of bud burst in nine sessile oak (Quercus petraea) populations distributed in central and northern Europe. The sampled populations were selected on the basis of their contrasting time of bud burst observed in common garden experiments (provenance tests). The candidate genes were selected according to their expression profiles during the transition from quiescent to developing buds and/or their functional role in model plants. The overall nucleotide diversity was large (π(tot)=6.15 × 10(-3); π(silent)=11.2 × 10(-3)), but population differentiation was not larger than for microsatellites. No outlier single-nucleotide polymorphism (SNP), departing from neutral expectation, was found among the total of 125 SNPs. These results contrasted markedly with the significant associations that were observed between the candidate genes and bud burst in segregating populations. Quantitative trait loci (QTLs) for bud burst were identified for 13 year*site seasonal observations in a cloned mapping pedigree. Nineteen QTLs were detected, and QTLs located on linkage groups 2, 5 and 9 contributed repeatedly to more than 12% of the phenotypic variation of the trait. Eight genes were polymorphic in the two parents of the pedigree and could be mapped on the existing genetic map. Five of them located within the confidence intervals of QTLs for bud burst. Interestingly, four of them located within the three QTLs exhibiting the largest contributions to bud burst.

Gene organization and transcriptional analysis of the Spiroplasma citri rpsB/tsf/x operon.

The nucleotide sequence of a 6863-bp Spiroplasma citri DNA fragment comprising the spiralin gene was determined. Sequence analysis revealed eight putative ORFs that encode ribosomal protein S2, elongation factor Ts, spiralin, 6-phosphofructokinase, pyruvate kinase, and three unidentified proteins (A, B, and X). The gene organization reported here is different from that previously published. Northern blot analysis of rpsB, tsf, and x transcripts indicates that these genes are organized into a single transcriptional unit (operon). However, the detection of an additional transcript corresponding to the rpsB gene alone suggests that a transcriptional mechanism should occur in the 3' region of the rpsB gene, allowing a conditional transcription termination.

Purification, cloning, and preliminary characterization of a Spiroplasma citri ribosomal protein with DNA binding capacity.

The rpsB-tsf-x operon of Spiroplasma citri encodes ribosomal protein S2 and elongation factor Ts, two components of the translational apparatus, and an unidentified X protein. A potential DNA-binding site (a 20-base pair (bp) inverted repeat sequence) is located at the 3' end of rpsB. Southwestern analysis of S. citri proteins, with a 30-bp double-stranded oligonucleotide probe (IRS), containing the 20-bp inverted repeat sequence and the genomic flanking sequences, detected an IRS-binding protein of 46 kDa (P46). P46 protein, which displays preferential affinity for the IRS, was purified from S. citri by a combination of affinity and gel filtration chromatographies. The native form of P46 seems to be homomultimeric as estimated by SDS-polyacrylamide gel electrophoresis analysis and gel filtration. A 3.5-kilobase pair S. citri DNA fragment comprising the P46 gene and flanking sequences was cloned and sequenced. Sequence analysis of this DNA fragment indicated that the P46 gene is located within the S10-spc operon of S. citri at the position of the gene coding for ribosomal protein L29 in the known S10-spc operons. The similarity between the N-terminal domain of P46 and the L29 ribosomal protein family and the presence of a 46-kDa IRS-binding protein in S. citri ribosomes indicated that P46 is the L29 ribosomal protein of S. citri. We suggest that P46 is a bifunctional protein with an L29 N-terminal domain and a C-terminal domain involved in IRS binding.

Peripheral pyogenic arthritis. A study of one hundred seventy-nine cases.

A retrospective medical record-based study of cases of peripheral pyogenic arthritis diagnosed in a rheumatology department between 1966 and 1993 was conducted. Of the 197 cases, 179 were evaluable. Pyogenic arthritis accounted for 0.68% of admissions and 30.3% of bone and joint infections during the study period. Incidence rose gradually from 2.2 new cases per year between 1966 and 1970 up to 6 to 10 new cases per year since 1991. In 88% of cases a single joint was involved, with the most commonly affected sites being the knee (32.5%), hip (22.2%), shoulder (12%) and sacroiliac joint (11.4%). Of the 22 patients with polyarticular arthritis, 19 had involvement of two joints. A portal of entry was identified in 53% of cases. Of the 13% of iatrogenic cases, half occurred after a local corticosteroid injection. The pathogen was identified in 65% of cases. Staphylococcus aureus was the most common organism (56%) followed by streptococci (9.5%) and E. coli (7%). Only three patients had gonococcal arthritis. Mean duration of therapy was four months. Although complications were exceedingly rare, three patients died and three others developed septic shock. Our data suggest that the presentation of pyogenic arthritis has remained essentially unchanged. In particular, we found no increase in iatrogenic forms, in contrast to recent experience with vertebral osteomyelitis.