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Self-incompatibility in Brassica is controlled by a single, highly polymorphic locus that extends over several hundred kilobases and includes several expressed genes. Two stigma proteins, the S locus receptor kinase (SRK) and the S locus glycoprotein (SLG), are encoded by genes located at the S locus and are thought to be involved in the recognition of self-pollen by the stigma. We report here that two different SLG genes, SLGA and SLGB, are located at the S locus in the class II, pollen-recessive S15 haplotype. Both genes are interrupted by a single intron; however, SLGA encodes both soluble and membrane-anchored forms of SLG, whereas SLGB encodes only soluble SLG proteins. Thus, including SRK, the S locus in the S15 haplotype contains at least three members of the S gene family. The protein products of these three genes have been characterized, and each SLG glycoform was assigned to an SLG gene. Evidence is presented that the S2 and S5 haplotypes carry only one or the other of the SLG genes, indicating either that they are redundant or that they are not required for the self-incompatibility response.

The self-incompatibility (SI) response in Brassica involves recognition of self-pollen by the papillar cells of the stigma and is mediated by the products of genes localized at the S (self-incompatibility) locus. Two S locus genes, SRK and SLG, are thought to encode components of a receptor complex present in the female partner. The putative gene product of SLA, a third S locus-linked gene that is expressed specifically in anthers, is a candidate for the male component of the SI recognition system. The identification of a mutant SLA allele, interrupted by a large insert resembling a retrotransposon, in self-compatible Brassica napus initially suggested that SLA played an essential role in the SI response. In this study, we have characterized an SLA allele from a self-compatible B. oleracea var acephala line and show that it too is interrupted by a large insert. However, analysis of seven B. oleracea var botrytis lines exhibiting both self-compatible and self-incompatible phenotypes showed that these lines carry an S allele very similar or identical to that of the B. oleracea var acephala line and that the SLA gene is interrupted by an insert in all seven lines. The insertion of the putative retrotransposon was shown to interfere with gene expression, with no SLA transcripts being detected by RNA gel blot analysis in a self-incompatible B. oleracea var botrytis line carrying an interrupted SLA gene. These data indicate that a functional SLA gene is not required for the SI response in Brassica.

Several staphylococcal species express a synergistic activity which potentiates hemolysis by beta-hemolysin. In Staphylococcus aureus, this activity is mediated by the delta-hemolysin, coded by the hld gene within the agr locus. In S. lugdunensis, the equivalent activity results from the production of 3 small peptides coded by an operon named slush, distinct from hld and located outside the agr region. We examined 15 clinically relevant staphylococcal species for the presence of hld, slush and agr by specific hybridisation. All species contained a recognizable agr-related locus. Three species never produced synergistic haemolysis and contained neither hld nor slush. Of the 12 producer strains, 5 contained hld, apparently within the agr region, 4 contained slush and one (S. caprae) contained both. Two other producer species (S. hominis and S. simulans) hybridised to neither probe.

A rapid polymerase chain reaction method was developed to differentiate Staphylococcus pasteuri from other staphylococcal species, especially the phenotypically similar S. warneri. The oligonucleotide probes used as primers were designed from the sequence of a S. pasteuri random amplified polymorphic DNA fragment.

A rapid commercial system (API 20 STREP gallery, API System, France) for the identification of streptococci was compared with conventional biochemical or serological methods. 77 clinical isolates from patients with infective endocarditis and six reference strains were tested. Biochemical tests showing differences between conventional methods and the API gallery were the acidification of inulin and the Voges-Proskauer reaction, but these differences did not affect the final identification of any strain. 75 strains were identified by the API system and 70 by conventional methods. 69 strains (25 groupable and 44 of 51 non-groupable streptococci) were given the same identity by both methods. One S. morbillorum was only identified by the conventional method. Seven S. sanguis I strains were identified only by the API system and confirmed by additional biochemical tests. The API gallery is a useful method for identifying streptococci associated with infective endocarditis, agreeing with conventional methods in 90% of strains. Results are usually available in 24 h.