The gene (sipA) encoding the sulfur-induced protein A (PF2025) is highly upregulated during growth of Pyrococcus furiosus on elemental sulfur (S0). Expression of sipA is regulated by sulfide, the product of S0 reduction, but in an iron-dependent manner. SipA is proposed to play a role in intracellular iron sulfide detoxification.

The mating pathway in yeast Saccharomyces cerevisiae has long been used to reveal new mechanisms of signal transduction. The pathway comprises a pheromone receptor, a heterotrimeric G protein, and intracellular effectors of morphogenesis and transcription. Polarized cell growth, in the direction of a potential mating partner, is accomplished by the G-protein ␤␥ subunits and the small G-protein Cdc42. Transcription induction, needed for cell-cell fusion, is mediated by G␤␥ and the mitogen-activated protein kinase (MAPK) scaffold protein Ste5. A potential third pathway is initiated by the G-protein ␣ subunit Gpa1. Gpa1 signaling was shown previously to involve the F-box adaptor protein Dia2 and an endosomal effector protein, the phosphatidylinositol 3-kinase Vps34. Vps34 is also required for proper vacuolar sorting and autophagy. Here, using a panel of reporter assays, we demonstrate that mating pheromone stimulates vacuolar targeting of a cytoplasmic reporter protein and that this process depends on Vps34. Through a systematic analysis of F-box deletion mutants, we show that Dia2 is required to sustain pheromone-induced vacuolar targeting. We also found that other F-box proteins selectively regulate morphogenesis (Ydr306, renamed Pfu1) and transcription (Ucc1). These findings point to the existence of a new and distinct branch of the pheromone-signaling pathway, one that likely leads to vacuolar engulfment of cytoplasmic proteins and recycling of cellular contents in preparation for mating. Many extracellular signals are detected by G-proteincoupled receptors (GPCRs). 10 In animals, these signals include odors, tastes, light, pH, nucleotides, biogenic amines, peptides, steroids, and phospholipids. In each case, receptor activation results in binding of GTP to a G-protein ␣ subunit and dissociation of G␣ from the ␤␥ subunit dimer. Both G␣ and G␤␥ can then transduce signals through the activation of intracellular enzymes and ion channels. G-protein signaling ends when GTP is hydrolyzed to GDP, a process that is accelerated by members of the regulator of G-protein signaling (RGS) family (1). GPCRs also play an important role in yeast mating. Genetic analysis in yeast Saccharomyces cerevisiae has led to the identification and characterization of several new signaling proteins, including the first RGS protein Sst2 (2). Sst2 is required for pheromone gradient tracking (3-5), adaptation (6, 7), and noise suppression (8). Other pathway components were identified from mutants that produce an unresponsive sterile (ste) phenotype, including the mating pheromone receptors (Ste2 and Ste3), the G-protein ␤␥ subunits (Ste4 and Ste18), a G␤␥ effector (Ste5), downstream protein kinases (Ste20, Ste11, and Ste7), and a transcription factor (Ste12) (2). Further analysis revealed that the G-protein ␤␥ dimer recruits and activates Far1 in complex with Cdc24 (9-13), an exchange factor for the small G-protein Cdc42 (14), as well as Ste5, a scaffold protein required for activation of the MAPKs Fus3 and Kss1 (15-22). Cdc42 promotes cell cy...

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Objectives: To report the clinical result of a series of patients who underwent intramedullary nailing (IMN) of tibial shaft fractures distal to a total knee arthroplasty (TKA).Design: Retrospective case series.Setting: Level-1 trauma center.Patients/Participants: Patients who sustained a tibial shaft fracture distal to a TKA treated with an IMN.Intervention: IMN of tibial shaft fractures distal to a TKA. Main Outcome Measurements:Postoperative weight-bearing status, readmissions, and complications or failure of treatment within 90 days; Knee Injury and Osteoarthritis Outcome Scores at the final follow-up; failure of treatment; and revision surgery.Results: Nine patients were included. The average age was 71.4 years (range 55-87 years). All TKAs were cemented. The average distance between the tibial keel and the cortical density of the tibial tubercle was 24.1 mm (range 19.5-26.7 mm). Six nails were inserted using an infrapatellar portal, 2 were inserted using a suprapatellar portal, and 1 was inserted using a lateral parapatellar approach. The median nail diameter was 10 mm (range 9-12 mm). All fractures were healed at the final follow-up. There were no infections or arthroplasty-related complications. Knee Injury and Osteoarthritis Outcome Scores ranged from 100% to 74% (median 82%). Conclusion:Overall, we report on the largest cohort in the literature undergoing IMN of a tibial shaft fracture distal to a TKA. We demonstrate that IMN of diaphyseal tibial fractures distal to a TKA can be performed safely. We additionally demonstrate that this treatment is highly effective in achieving fracture union with no arthroplasty-related complications.

Ubiquitination is a post‐translational modification that regulates protein activity by tagging specific substrates for degradation. Regulation of proteins by ubiquitination has been demonstrated to help terminate the response to mating pheromone in budding yeast. The yeast pheromone response is comprised of two branches, one leading to MAPK activation and gene transcription, the other leading to cellular polarization and shmoo formation. The Skp1/Cdc53/F‐box (SCF) ubiquitin ligase employs different F‐box subunits to recruit specific substrates for ubiquitination. In yeast, F‐box proteins have been identified as interchangeable components of the SCF complex. To identify pathway regulators, we conducted a screen in which we measured activation of the pheromone response in 16 yeast strains ‐‐ each lacking one of the candidate F‐box genes. We characterized the abilities of these deletion mutants to affect either the MAPK or the polarity branch of the pathway. Our study reveals that one F‐box protein, Pfu1, selectively regulates the polarity branch. Using live cell imaging in a microfluidic chamber, we demonstrate that Pfu1 is required to restrict the cell to a single polarity site. In contrast, Pfu1 is has no effect on MAP kinase activation or transcriptional induction. While polar axis formation is a fundamental and well characterized feature of budding, the mechanisms used to regulate cell polarity components during mating are largely unknown. The existence of an F‐box protein exclusively involved in mating projection development reveals ubiquitination as a means to independently regulate branches of a signal transduction pathway.