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Due to evolutionary conservation of biology, experimental knowledge captured from genetic studies in eukaryotic model organisms provides insight into human cellular pathways and ultimately physiology. Yeast chemogenomic profiling is a powerful approach for annotating cellular responses to small molecules. Using an optimized platform, we provide the relative sensitivities of the heterozygous and homozygous deletion collections for nearly 1800 biologically active compounds. The data quality enables unique insights into pathways that are sensitive and resistant to a given perturbation, as demonstrated with both known and novel compounds. We present examples of novel compounds that inhibit the therapeutically relevant fatty acid synthase and desaturase (Fas1p and Ole1p), and demonstrate how the individual profiles facilitate hypothesis-driven experiments to delineate compound mechanism of action. Importantly, the scale and diversity of tested compounds yields a dataset where the number of modulated pathways approaches saturation. This resource can be used to map novel biological connections, and also identify functions for unannotated genes. We validated hypotheses generated by global two-way hierarchical clustering of profiles for (i) novel compounds with a similar mechanism of action acting upon microtubules or vacuolar ATPases, and (ii) an un-annotated ORF, YIL060w, that plays a role in respiration in the mitochondria. Finally, we identify and characterize background mutations in the widely used yeast deletion collection which should improve the interpretation of past and future screens throughout the community. This comprehensive resource of cellular responses enables the expansion of our understanding of eukaryotic pathway biology.

SummaryWith renewed calls for malaria eradication, next-generation antimalarials need be active against drug-resistant parasites and efficacious against both liver- and blood-stage infections. We screened a natural product library to identify inhibitors of Plasmodium falciparum blood- and liver-stage proliferation. Cladosporin, a fungal secondary metabolite whose target and mechanism of action are not known for any species, was identified as having potent, nanomolar, antiparasitic activity against both blood and liver stages. Using postgenomic methods, including a yeast deletion strains collection, we show that cladosporin specifically inhibits protein synthesis by directly targeting P. falciparum cytosolic lysyl-tRNA synthetase. Further, cladosporin is >100-fold more potent against parasite lysyl-tRNA synthetase relative to the human enzyme, which is conferred by the identity of two amino acids within the enzyme active site. Our data indicate that lysyl-tRNA synthetase is an attractive, druggable, antimalarial target that can be selectively inhibited.

Objective To design a new method for oral preparation of urine for sperm retrieval after retrograde ejaculation (RE) and to test the motility of sperm exposed to prepared and unprepared urine. Design In vitro testing of urine conditions and sperm motility. Setting Assisted conception unit at a teaching hospital in the United Kingdom. Patient(s) Ten healthy volunteers to provide urine and sperm specimens from men attending the unit for semen analysis. Intervention(s) Various solutions of sodium bicarbonate and sodium chloride were drunk by a single subject until a suitable regimen was achieved. This regimen (called the Liverpool solution) was then tested on 10 volunteers. Samples of sperm were then added to prepared urine, unprepared urine, and culture medium, and the motility was analyzed. Main Outcome Measure(s) Urinary pH and osmolarity, sperm motility. Result(s) Urine produced by the 10 volunteers had a mean pH of 7.47 (range, 7.23–7.79) and a mean osmolarity of 289 mOsmol/L (range, 225–412 mOsmol/L), similar to that of medium. The progressive motility of sperm exposed to the unprepared urine was reduced (42.4% of sperm in medium), whereas that in the prepared urine was similar to that in the control medium. Conclusion(s) Liverpool solution can be used in any unit treating couples with RE, and it is a noninvasive and inexpensive regimen that may optimize urine pH and osmolarity for sperm survival after RE.

Objective To describe the laparoscopic management of an interstitial gestation of a heterotopic pregnancy. Design Case report and technique description. Setting Tertiary-level private practice. Patient(s) Woman with a 6-week gestation spontaneous heterotopic twin pregnancy: one twin intrauterine, one interstitial. Intervention(s) A purse-string suture was applied to the proximal portion of the interstitial heterotopic pregnancy. Main Outcome Measure(s) To enable a cornual resection to be performed with minimal bleeding and without recourse to laparotomy. Result(s) At 8 weeks gestation an ultrasound scan confirmed a viable singleton intrauterine pregnancy, but a scan at 12 weeks showed a missed miscarriage. Conclusion(s) The embedding of the suture into the uterine serosa prevents slipping of the ligature that could occur with a pretied loop.

Objective To describe a potential new use of gonadotropin-releasing hormone (GnRH) antagonists. Design Case report. Setting Assisted conception unit at a teaching hospital in the United Kingdom. Patient(s) A 37-year-old woman undergoing in vitro fertilization (IVF) who accidentally stopped using GnRH agonists after starting ovarian stimulation. Intervention(s) A GnRH antagonist was used to avoid a luteinizing hormone (LH) surge and hence "rescue" the cycle. Result(s) Successful oocyte retrieval was carried out, two embryos transferred, and a viable twin pregnancy ensued. Conclusion(s) This may be a new indication for the use of GnRH antagonists.