The Drosophila sex determination hierarchy controls all aspects of somatic sexual differentiation, including sex-specific differences in adult morphology and behavior. To gain insight into the molecular-genetic specification of reproductive behaviors and physiology, we identified genes expressed in the adult head and central nervous system that are regulated downstream of sex-specific transcription factors encoded by doublesex (dsx) and fruitless (fru). We used a microarray approach and identified 54 genes regulated downstream of dsx. Furthermore, based on these expression studies we identified new modes of DSX-regulated gene expression. We also identified 90 and 26 genes regulated in the adult head and central nervous system tissues, respectively, downstream of the sex-specific transcription factors encoded by fru. In addition, we present molecular-genetic analyses of two genes identified in our studies, calphotin (cpn) and defective proboscis extension response (dpr), and begin to describe their functional roles in male behaviors. We show that dpr and dpr-expressing cells are required for the proper timing of male courtship behaviors.

Understanding the fine-structure molecular architecture of bacterial epidemics has been a long-sought goal of infectious disease research. We used short-read-length DNA sequencing coupled with mass spectroscopy analysis of SNPs to study the molecular pathogenomics of three successive epidemics of invasive infections involving 344 serotype M3 group A Streptococcus in Ontario, Canada. Sequencing the genome of 95 strains from the three epidemics, coupled with analysis of 280 biallelic SNPs in all 344 strains, revealed an unexpectedly complex population structure composed of a dynamic mixture of distinct clonally related complexes. We discovered that each epidemic is dominated by micro-and macrobursts of multiple emergent clones, some with distinct strain genotype-patient phenotype relationships. On average, strains were differentiated from one another by only 49 SNPs and 11 insertion-deletion events (indels) in the core genome. Ten percent of SNPs are strain specific; that is, each strain has a unique genome sequence. We identified nonrandom temporal-spatial patterns of strain distribution within and between the epidemic peaks. The extensive full-genome data permitted us to identify genes with significantly increased rates of nonsynonymous (amino acid-altering) nucleotide polymorphisms, thereby providing clues about selective forces operative in the host. Comparative expression microarray analysis revealed that closely related strains differentiated by seemingly modest genetic changes can have significantly divergent transcriptomes. We conclude that enhanced understanding of bacterial epidemics requires a deep-sequencing, geographically centric, comparative pathogenomics strategy.Streptococcus pyogenes | evolution | invasive disease | phylogeography | population genetics

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Summary. Genetic variants in the GP1BA and ITGA2 genes have been proposed as potential modifiers for arterial vascular disease and bleeding disorders. Since ancestry may play an important role in the prevalence of these variants, we sought to determine their allele frequency and linkage disequilibrium in a collection of 1064 DNA samples from 51 ethnic groups. We studied haplotypes of ITGA2 defined by single nucleotide substitutions at positions )52, 807, and 1648, and GP1BA variants defined by sequence changes in positions )5 (Kozak), 1018 (T145M, HPA-2) and 1285 (VNTR A, B, C and D). Frequency of haplotypes of ITGA2 showed considerable variation across the different groups, with a higher prevalence of the haplotype )52C or T/807C/1648A observed in African compared with caucasian and Asian populations. The haplotypes 52C/807T/1648A and )52T/807T/1648A were not observed in caucasians or South Americans. While relative frequencies of the GP1BA Kozak alleles were comparable across groups, the methionine allele (HPA-2b) showed a higher frequency in Africa (0.26) than in the other groups. We also observed a high prevalence of the VNTR B allele in the African and Israeli populations. Haplotype analysis revealed incomplete linkage disequilibrium between the HPA-2 and VNTR alleles. Incorporation of GP1BA variants into the set of SNPs already genotyped by the HapMap project disrupted the pre-existing haplotype block. These data provide a valuable resource for optimal selection of variants best tailored for association studies of vascular disease or bleeding disorders when examining individuals of different ancestral origins.

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