There are still a number of differences in opinion concerning the essential factors affecting the production of citric acid. The medium used in the present investigation was prepared with commercial glucose, purified by an aluminum hydroxide coprecipitation method. Systematic variation of the concentrations of the inorganic constituents of this medium gave results indicative of the nature of the relations between certain of the constituents and the accumulation of citric acid in the culture. EXPERIMENTAL DATA All experiments were run in shake flasks. The incubation temperature was 25 C. Experimental conditions and methods of analysis were the same as described in previous papers (Shu and Johnson, 1947, 1948). Aspergillus niger 72-4 (Shu and Johnson, 1947) was employed in all experiments unless otherwise stated. The composition of the basal medium is given in table 1.

Nitric oxide (NO) modulates many physiological events through production of cGMP from its receptor, the NO-sensitive guanylyl cyclase (GC1). NO also appears to function in a cGMP-independent manner, via -nitrosation (SNO), a redox-based modification of cysteine thiols. Previously, we have shown that-nitrosated GC1 (SNO-GC1) is desensitized to NO stimulation following prolonged NO exposure or under oxidative/nitrosative stress. In animal models of nitrate tolerance and angiotensin II-induced hypertension, decreased vasodilation in response to NO correlates with GC1 thiol oxidation, but the physiological mechanism that resensitizes GC1 to NO and restores basal activity is unknown. Because GC1 interacts with the oxidoreductase protein-disulfide isomerase, we hypothesized that thioredoxin-1 (Trx1), a cytosolic oxidoreductase, could be involved in restoring GC1 basal activity and NO sensitivity because the Trx/thioredoxin reductase (TrxR) system maintains thiol redox homeostasis. Here, by manipulating activity and levels of the Trx1/TrxR system and by using a Trx1-Trap assay, we demonstrate that Trx1 modulates cGMP synthesis through an association between Trx1 and GC1 via a mixed disulfide. A proximity ligation assay confirmed the endogenous Trx1-GC1 complex in cells. Mutational analysis suggested that Cys in GC1 is involved in the Trx1-GC1 association and modulation of GC1 activity. Functionally, we established that Trx1 protects GC1 from -nitrosocysteine-induced desensitization. A computational model of Trx1-GC1 interaction illustrates a possible mechanism for Trx1 to maintain basal GC1 activity and prevent/rescue GC1 desensitization to NO. The etiology of some oxidative vascular diseases may very well be explained by the dysfunction of the Trx1-GC1 association.

PGE2 has been implicated in prostate cancer tumorigenesis. We hypothesized that abnormal prostaglandin receptor (EPR) expression may contribute to prostate cancer growth. Twenty-six archived radical prostatectomy specimens were evaluated by immunohistochemistry (IHC) and Western blotting for the expression of EP1, EP2, EP3, and EP4. As a corollary, EPR expression in one normal (PZ-HPV7) and four prostate cancer cell lines (CA-HPV10, LNCaP, PC3, and Du145) were assessed by Western blotting. Prostate cancer and normal cell growth were compared in vitro after EPR blockade, siRNA EPR knockdown, or overexpression. EP1, EP2, EP3, and EP4 receptors were detected by IHC in all areas of benign tissue within the clinical prostate cancer specimens. In areas of prostate cancer, EP4 and EP2 were overexpressed in 85% (22 of 26) and 75% (18 of 24) and EP3 expression was reduced in all (26 of 26, 100%) specimens (P < 0.05 vs. benign tissue). EP1 showed no specific differential expression pattern. Increased EP4 and reduced EP3 was confirmed by Western blotting in fresh clinical specimens and in prostate cancer cell lines (CA-HPV10, LNCaP, PC3, and Du145) compared with the normal prostate cell line (PZ-HPV7). EP2 and EP4 siRNA knockdown resulted in reduced in vitro growth and metastasis-related gene expression (MMP9 and Runx2) of prostate cancer lines, and in vitro migration was inhibited by EP4 antagonists. As a corollary, EP3-overexpressing PC3 cells displayed impaired growth in vitro. Human prostate cancer is associated with EP4 and EP2 overexpression and reduced EP3 expression. These data suggest that targeting specific EPR may represent a novel therapeutic approach for prostate cancer.

A B S T R A C TMulberry bacterial blight caused by Pseudomonas syringae pv. mori, is one of the most serious diseases on mulberry (Morus alba L.), and threatens sericulture development. An endophytic Pantoea agglomerans SWg2 (referred to as SWg2), originally isolated from roots of healthy mulberry, is extremely inhibitory activity to P. syringae. Greenhouse tests were first conducted to examine the biological control properties of SWg2. A suspension of SWg2, introduced to the host plant, significantly reduced disease symptoms caused by P. syringae. Likewise, when a suspension of SWg2 was sprayed onto plantlets 2 days before inoculation with P. syringae, its disease control efficacy was up to 65.6% even after inoculation with P. syringae 18 days later. Interestingly, the control effect of the traditional agrochemical streptomycin was just 33.2% at 18 days post inoculation (DPI), although it was 55.6% at 9 DPI. Furthermore, SWg2 promoted the growth of mulberry seedlings. The immersion of 10 7 CFU mL −1 suspension of SWg2 had the most distinctive growth-promoting role since the seed germination rate and radicle length development were enhanced up to 100% and 144.2%, respectively. Based on the green fluorescent protein (GFP) labeling technique and a re-isolation method, it was determined that the SWg2 strain colonized and spread in mulberry seedlings. The bacteria entered seedlings through the areas of emergence of root hairs and cracks in the rhizodermis. Eventually these cells spread to other tissues of the plant with colonization occurring mainly in the intercellular spaces. Furthermore, the GFP-tagged SWg2 strain could be detected in stems and leaves, but the quantity was smaller than that in roots. There appears to be no outward negative effects of SWg2 on treated plants and silkworms feed on them in a normal manner. This work indicates that P. agglomerans SWg2 possesses the biological potential to provide protection of its host against the pathogen of mulberry bacterial blight will at the same time promoting the growth and vigor of the host plant.

A study was made of the effects of oxygen tension and inorganic phosphate concentration on the production of glycerol, arabitol, and ethanol by a strain of osmophilic yeast. Increasing the oxygen tension increased the yields of glycerol and arabitol and decreased the yield of ethanol, while increasing the concentration of inorganic phosphate had the opposite effect.The changes in yields of products with increasing phosphate concentration were most pronounced at a partial pressure of oxygen of 280 mm. of mercury. At lower oxygen tensions the yields of polyols were low and the yield of ethanol was high at all concentrations of phosphate, while at very high oxygen tensions the opposite effect was observed. When the ethanol yield was high, the respiratory quotient was also high. These results are discussed in relation to the oxidative phosphate-lack theory of the Pasteur effect.