Further evidence for the existence of a bottleneck in the metabolism of Saccharomyces cerevisiae

The growth physiology of Saccharomyces cerevisiae strains H1022 and Whi2+ has been studied in aerobic batch and continuous (chemostat) cultures. Results from the measurement of biomass and medium components (off-line) together with oxygen, carbon dioxide and heat measurements (on-line) have been used in an attempt to explore the existence of 'overflow' or 'bottleneck' metabolism as opposed to catabolite repression (Crabtree effect) in these strains. Chemostat experiments indicated that specific oxygen uptake rate (qO2) was linearly related to the dilution rate (D) at values below the critical dilution rate (D crit), becoming constant above D crit, which is in agreement with the bottleneck theory. However, batch culture experiments indicated negligible oxygen consumption during the initial glucose growth phase, the culture exhibiting purely anaerobic metabolism. The bottleneck theory would propose that qO2 has a constant (maximum) value under these conditions. The results presented here suggest that while the bottleneck theory can be adequately used to describe chemostat growth of S. cerevisiae, some other control mechanism must be operating under conditions of high glucose concentrations, such as those initially prevailing in the batch culture experiments.     

济南城市化进程中的交通问题及对策研究

在分析城市化对交通影响的基础上，着重讨论了济南市目前城市交通问题的现状及深层次的原因，并提出了相应的建议。     

Increase in the total reducing substances in the hemolymph of the freshwater crab,Barytelphusa guerini,produced by a pesticide (DDT) and an indolealkylamine (serotonin)

Summary DDT and serotonin produced significant increases in the total reducing substances in the hemolymph of intact crabs,Barytelphusa guerini, apparently by triggering release of the hyperglycemic hormone.     

The angiotensin converting enzyme inhibitor enalapril in acute ischemic renal failure in rats

The influence of the renin-angiotensin system on renal hemodynamics, tubular pressure and tubulo-glomerular feedback was investigated with the angiotensin converting enzyme inhibitor MK 421 (enalapril), in uninephrectomized rats with and without ischemia-induced acute renal failure. In animals with normal renal function proximal tubular pressure and tubulo-glomerular feedback response were lowered by enalapril long-term treatment, whereas glomerular filtration rate and renal blood flow were not influenced by the drug. After 45 and 70 minutes ischemia there was no difference between treated and untreated animals in the severely impaired glomerular filtration rate. Renal blood flow remained unaffected by the treatment. The histological damage due to ischemia (tubular casts, tubular necrosis and medullary capillary congestion) was not influenced by enalapril. As tubulo-glomerular feedback had been significantly inhibited during renin-angiotensin inhibition, its importance in mediating acute renal failure remains doubtful; other factors such as tubular obstruction and medullary congestion may be crucial.