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Nucleic acid and protein synthesis were studied in temperature-sensitive mutants defective in phospholipid synthesis. The defect is due to a single mutation in glycerol 3-phosphate acyltransferase (EC 2.3.1.15). The results show that at the restrictive temperature not only does phospholipid synthesis cease, but DNA, RNA, and protein synthesis also cease. Active transport continues, however, indicating that the cells do not become leaky or lose their energy supply. These results suggest that phospholipid synthesis is coupled to DNA, RNA, and protein synthesis.Since lipid synthesis, and consequently membrane synthesis, is necessary for growth of cells, it is reasonable that cells would have regulatory mechanisms to couple the synthesis of lipids with the synthesis of macromolecules in order to maintain balanced cell growth. The availability of mutants in lipid biosynthesis has helped to elucidate the contribution of phosl)holipids to membrane structure and function (1). In particular, one apparent result was that protein synthesis and cell growth could continue for a significant amount of time in the absence of lipid synthesis. When an unsaturated fattyacid auxotroph of Escherichia coli was deprived of unsaturated fatty acids, growth, as well as DNA, RNA, and protein synthesis, continued for several hours (2-5). Similar results were obtained when 3-decynoyl-N-acetylcysteamine was used to inhibit unsaturated fatty-acid synthesis (4, 6, 7). Bacillus subtilis (8-10), Staphylococcus aureus (11), and E. coli (12) glycerol auxotrophs have been studied. When these mutants were deprived of glycerol, net phospholipid synthesis stopped immediately. However, macromolecular synthesis and cell growth continued for some time.Recently this laboratory has described a temperaturesensitive mutant of E. coli, CV15, that does not grow or make phospholipid at the restrictive temperature (13). The defect is due to a single mutation in glycerol 3-phosphate acyltransferase (EC 2.3.1.15), which catalyzes the first reaction unique to phospholipid biosynthesis. In this paper, detailed studies of the synthesis of phospholipid, DNA, RNA, and protein are reported for mutants with a thermolabile glycerol 3-phosphate acyltransferase. The results show that DNA, RNA, and protein synthesis do not continue at the restrictive temperature; the shutoff of the synthesis of these macromolecules parallels the shutoff of phospholipid synthesis. Active transport continues, however, indicating that the cells do not become leaky or lose their energy supply. MATERIALS AND METHODSBacterial Strains, Mfedia, and Growth Conditions. CV15 and its parent, strain 8, were described previously (13).Abbreviations: TMG, methyl-l-thio-j-D-galactopyranoside; IPTG, isopropyl-l-thio-,f-D-galactopyranoside.

Single-ISA heterogeneous multicore processors have gained increasing popularity with the introduction of recent technologies such as ARM big.LITTLE. These processors offer increased energy efficiency through combining low power inorder cores with high performance out-of-order cores. Efficiently exploiting this attractive feature requires careful management so as to meet the demands of targeted applications. In this paper, we explore the design of those architectures based on the ARM big.LITTLE technology by modeling performance and power in gem5 and McPAT frameworks. Our models are validated w.r.t. the Samsung Exynos 5 Octa (5422) chip. We show average errors of 20% in execution time, 13% for power consumption and 24% for energy-to-solution.

Spontaneous hemopneumothorax is a serious condition complicating spontaneous pneumothorax. Early stage thoracotomy has been advocated to stop the bleeding and evacuate the coagulated blood from the pleural cavity. The present review was undertaken to emphasize the potential life-threatening condition of spontaneous hemopneumothorax and reassess the benefit of conservative treatment with chest tube drainage. Out of six patients, five patients were treated conservatively and one required an emergency thoracotomy because of cardiovascular collapse. Although three patients still had minimal residual hemopneumothorax on discharge, none of them developed empyema or trapped lung. In conclusion, conservative treatment is efficient and should be performed if bleeding persists for less than 24 hours after chest tube placement.

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