Two toxoflavin biosynthesis-related proteins (TRP-1, TRP-2) from wild strains of the phytopathogen Burkholderia glumae were previously identified, and toxA was determined to encode TRP-1, which has characteristics of a methyltransferase. An 8.2-kb region in the chromosomal DNA of B. glumae that contains the tox operon (toxABCDE) and an upstream regulatory gene (toxR) involved in phytotoxin toxoflavin biosynthesis was cloned and sequenced in this study. The sequence downstream of toxA contains four open reading frames -toxB, toxC, toxD and toxE -which encode polypeptides with calculated molecular masses of 23.3, 61.6, 34.9, and 38.3 kDa, respectively, all having the same transcriptional orientation as toxA. Mutants disrupted in the tox operon lost their ability to produce toxoflavin and did not induce typical chlorosis on infected rice panicles. Based on results from reverse transcription-polymerase chain reaction experiments, the message encoded by the tox operon may be polycistronic for all five genes. Also, the toxR gene was located upstream of this operon. The toxR gene product, with a calculated molecular mass of 37.5 kDa, might be a member of the LysR family of regulatory molecules and an activator that allows transcription of the tox operon. Furthermore, the deduced proteins of ToxB and ToxE had significant similarity to the GTP cyclohydrolase II and the deaminase, respectively, involved in riboflavin synthesis in several organisms. These results suggest that toxoflavin is synthesized in part through a biosynthetic pathway common to the synthesis of riboflavin, starting with GTP as the precursor.

Pacemapping and activation mapping provide similar localizing information. The spatial resolution of each technique is modest, varies between patients, and may be optimized by three-dimensional data display.

Both diversity of symptoms and variability of the severity of symptoms, especially walk-in mode of admission lead ER physicians to miss AAD in about 1 in 6 cases of AAD. It is therefore important to keep AAD as a differential diagnosis in mind, even when patients present with mild enough symptoms that allow them to walk into the ER.

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The addition of iron to an iron-deficient medium markedly enhanced the growth of "Pseudomonas plantarii" and the production of red crystals. However, it markedly reduced the amount of dissolved tropolone, a product of the bacterium and an iron chelator, and the production of an iron-regulated protein (78 kilodaltons). The red crystal was complex, composed of tropolone and iron, the ratio being 3:1. "Pseudomonas plantarii," recently reported to be the causal agent for seedling blight of rice grown in nursery boxes, produces tropolone (Fig. 1)(4, 5). The term tropolone was proposed in 1945 for the seven-member ring structure in colchicine and mold metabolite stipitatic acid (7, 8). In 1980, tropolone itself was found to be produced in nature; i.e., it