Identification of molecular markers associated with leptine in reciprocal backcross families of diploid potato.

Solanum phureja clone 1-3 and S. chacoense clone 80-1 have a zero and high leptine content in their foliage, respectively. An F(1) hybrid (CP2) was intermediate for the trait, but self-incompatible. Two reciprocal backcross families, PBCp ( phu 1-3 x CP2) and PBCc (CP2 x phu 1-3), and a family of monoploids derived by anther culture of CP2, were characterized for leptine as the aglycon, acetylleptinidine (ALD), content in leaves by gas chromatography. ALD was present in 43 of 87 genotypes in the PBCp backcross, implying simple genetic control by a dominant gene. However, the ALD levels were low compared to CP2. In the PBCc backcross, only 7 of 42 genotypes expressed ALD at a level generally higher than in PBCp. This ratio was significantly different from the 1:1 segregation observed in the reciprocal backcross and suggests a cytoplasmic influence. ALD levels in the CP2 monoploids ranged from 0 to 8,968 &mgr;g.g(-1) of dry weight (dw) with 18 individuals expressing ALD and five with 0 ALD content. Ten high (mean ALD = 546 &mgr;g.g(-1) of dw) and ten low (mean ALD = 0) individual plants within PBCp and seven high (mean ALD = 3,037 &mgr;g.g(-1) of dw) and eight low (mean ALD = 0) individual plants within PBCc were used for bulk segregant analysis (BSA) using 214 RAPD (randomly amplified polymorphic DNA) primers. Three RAPD primers (OPQ-2, OPT-16 and OPT-20) amplified bands exclusively in bulks containing DNA mixes of high ALD producers in both PBCp and PBCc populations. These results suggest that these markers were associated in coupling to ALD content. ANOVAs for ALD content verified association between the markers and the trait. A CAPS (cleaved amplified polymorphic sequence) marker, GP82A, was also significantly associated with ALD production in both the monoploid and the PBCp populations. None of the RAPD markers was associated to ALD in the monoploids but one was associated in repulsion. The monoploid data indicate the likelihood of a recessive gene(s) that controls leptine production, but the backcross data indicate the action of modifying loci.

Development of microsatellite markers in potato and their use in phylogenetic and fingerprinting analyses.

Three genomic libraries were constructed using a mixture of DNA from Solanum phureja Juz. & Buk., and S. chacoense Bitt. Two of the libraries were enriched for ATT and GT repeats (a 27-fold enrichment was achieved). In total, 3500 clones of the conventional library, 1,000 of the library enriched for ATT, and 12,000 of the one enriched for GT were screened with five different repeat motifs, and a total of 18 primer pairs was obtained. Another group of 12 primer pairs was obtained from the SSR-containing sequences in the public databases (18 SSR-containing sequences were utilized). From among 30 newly developed primer pairs, 12 previously published ones, and 12 pairs developed for tomato, 7 were used to identify 12 different potato cultivars and introductions, and 12 were used to study phylogenetic distance among seven wild and cultivated potato species. Two SSR markers were sufficient to discriminate the 12 cultivars. The mean number of alleles per polymorphic locus was 5 for the 12 cultivars and 4.5 for the seven species. The results obtained in this study confirm those achieved in similar studies in other plant species regarding the abundance and use of SSR markers in identifying species and cultivars.

'Dry sex' and HIV infection among women attending a sexually transmitted diseases clinic in Lusaka, Zambia.

OBJECTIVES: To describe 'dry sex' practices intended to decrease vaginal secretions and to determine whether these practices are related to HIV infection. SUBJECTS AND METHODS: A cross-sectional study was conducted in a sexually transmitted diseases clinic in a teaching hospital in Lusaka, Zambia. The subjects comprised 329 women aged 15-50 years presenting consecutively for an initial evaluation of sexually transmitted disease symptoms. Dry sex practices were assessed by questionnaire, and serological testing for HIV antibodies was performed. RESULTS: Fifty percent of women had engaged in at least one dry sex practice. The most common practices were drinking 'porridge' (a liquid or suspension believed to cause drying of the vagina; 28%), removing vaginal secretions with a cloth (22%) and placing leaves in the vagina (11%). The most frequent reasons given for drinking porridge were to increase the partner's sexual enjoyment and to tighten the vagina, while cleaning the vagina was mentioned often by those using cloth or leaves. Swelling or peeling of the vagina was reported by approximately 10% of women using cloth or leaves. Overall, the HIV seroprevalence in the sample was 58%. In bivariate analysis, no practice was statistically significantly associated with HIV infection. Multiple logistic regression had little impact on these findings. CONCLUSIONS: Although a variety of practices with potential relevance to HIV transmission were reported, there was no evidence in this study population of a strong relationship between these practices and HIV infection. Women should be counseled about the potential risks of these practices, but prevention efforts should continue to emphasize measures of known effectiveness, particularly limiting the numbers of sexual partners, consistently using condoms and obtaining appropriate treatment for sexually transmitted diseases.