Peritumoral diffusion-tensor MR imaging metrics enable the differentiation of solitary intraaxial metastatic brain tumors from gliomas. In addition, the TII enables one to distinguish presumed tumor-infiltrated edema from purely vasogenic edema.

Bacterial strain Burkholderia contaminans MS14 was isolated from soil that suppressed brown patch disease of lawn grass. An antifungal compound was purified from the liquid culture of this bacterium. In this study, complete covalent structures of two purified closely related antifungal compounds were determined by the experiments of TOCSY, NOESY, ROESY, 13C HSQC 2D NMR, and ESI-MS and GC. The analysis of monoisotopic masses of the purified preparation indicated presence of two related compounds with masses determined to be 1199.543 Da and 1215.518 Da; the difference corresponds to the mass of an oxygen atom. GC analysis identified a xylose sugar attached to the antifungal compound. NMR experiments revealed that the compound is cyclic and composed of eight amino acids, two of which are β-hydroxy derivatives of Tyr and Asn, and one being a novel amino acid. The novel amino acid serves as the scaffold for the attachment of the xylose and a short acyl chain. The spectrum and concentration of antifungal activity was determined using a microtiter plate assay. The antifungal compound demonstrated potent antifungal activities against a broad panel of fungal plant and animal pathogens, as well as two Pythium spp. Microscopic observations showed that the antifungal compound disrupts normal membrane morphology. The cells fill with large inclusion bodies and the membrane becomes irregularly shaped and swollen following the exposure to sub-inhibitory concentrations of the antifungal compound. Our data support the identification of a novel fungicide and the compound has been named occidiofungin, meaning fungal killer.

The bacterial diversity associated with citrus leaf midribs was characterized for citrus groves that contained the Huanglongbing (HLB) pathogen, which has yet to be cultivated in vitro. We employed a combination of high-density phylogenetic 16S rRNA gene microarrays and 16S rRNA gene clone library sequencing to determine the microbial community composition for symptomatic and asymptomatic citrus midribs. Our results revealed that citrus leaf midribs can support a diversity of microbes. PhyloChip analysis indicated that 47 orders of bacteria in 15 phyla were present in the citrus leaf midribs, while 20 orders in 8 phyla were observed with the cloning and sequencing method. PhyloChip arrays indicated that nine taxa were significantly more abundant in symptomatic midribs than in asymptomatic midribs. "Candidatus Liberibacter asiaticus" was detected at a very low level in asymptomatic plants but was over 200 times more abundant in symptomatic plants. The PhyloChip analysis results were further verified by sequencing 16S rRNA gene clone libraries, which indicated the dominance of "Candidatus Liberibacter asiaticus" in symptomatic leaves. These data implicate "Candidatus Liberibacter asiaticus" as the pathogen responsible for HLB disease.

Sequence analysis of the right border of the syr gene cluster of Pseudomonas syringae pv. syringae strain B301D revealed the presence of the salA gene 8,113 bp downstream of syrE. The predicted SalA protein of strain B301D differs by one amino acid from that of strain B728a. Two homologs of salA, designated syrF and syrG, were identified between syrE and salA. All three proteins contain helix-turn-helix DNA-binding motifs at their C termini and exhibit homology to regulatory proteins of the LuxR family. A salA mutant failed to produce syringomycin, whereas syrF and syrG mutants produced 12 and 50%, respectively, of syringomycin relative to the wild-type strain. The salA, syrF, and syrG mutants were significantly reduced in virulence, forming small, nonspreading lesions in immature cherry fruits. Translational fusions to the uidA gene were constructed to evaluate expression of syrB1 in regulatory mutant backgrounds and to determine the relationship among the three regulatory loci. Expression of a syrB1::uidA fusion required functional salA and syrF genes and, in series, the expression of a syrF::uidA fusion required a functional salA gene. These results demonstrate that salA is located upstream of syrF in the regulatory hierarchy controlling syringomycin production and virulence in P. syringae pv. syringae.