Xylan Synthase Activity in Isolated Mesophyll Cells of Zinnia elegans during Differentiation to Tracheary Elements

A paniculate fraction obtained from mesophyll cells of Zinniaelegans that were differentiating into tracheary elements exhibitedxylan synthase activity, catalyzing the transfer of ^MC-xylosefrom UDP-D-[U-¹⁴C]-xylose into 1,4-linked xylan. The activityincreased transiently at the same time as thickening of secondarycell walls occurred, a process that is accompanied by the depositionof cellulose, xylan and lignin. (Received August 3, 1990; Accepted December 6, 1990)     

Review of the East Asian species of the genera Hybrizon Fallén and Ghilaromma Tobias (Hymenoptera: Ichneumonidae: Hybrizontinae)

East Asian species of the genera Hybrizon and Ghilaromma are reviewed. Four species of Hybrizon, H. buccatus (Brébisson 1825), H. ghilarovi Tobias, 1988, H. juncoi (Ceballos 1957) and H. flavofacialis Tobias, 1988 and two species of Ghilaromma, G. orientalis Tobias, 1988 and G. ussuriensis Tobias, 1988, were recognized. H. ghilarovi was recorded from Korea, Japan and China, while H. juncoi was recorded from Korea, for the first time. The specimens recorded from Japan as G. fuliginosi (Wilkinson, 1930) by Watanabe (1984) are referred to G. orientalis herein. This species is newly recorded from Korea and Japan. Keys to East Asian species of Hybrizon and the world species of Ghilaromma are also provided.     

Sulfonamide-based non-alkyne LpxC inhibitors as Gram-negative antibacterial agents

We attempted to optimize sulfonamide-based non-alkyne LpxC inhibitors by focusing on improvements in enzyme inhibitory and antibacterial activity. It was discovered that inhibitors possessing 2-aryl benzofuran as a hydrophobe exhibited good activity. In particular, compound 21 displayed impressive antibacterial activity (E. coli MIC = 0.063 μg/mL, K. pneumoniae MIC = 0.5 μg/mL, and P. aeruginosa MIC = 0.5 μg/mL), and is a promising lead for further exploration as an antibacterial agent.     

Bleomycin-induced β-lactamase overexpression in Escherichia coli carrying a bleomycin-resistance gene from Streptomyces verticillus and its application to screen bleomycin analogues

Abstract A bleomycin-resistance gene, designated blmA , has been cloned from bleomycin-producing Streptomyces verticillus by Sugiyama et al. (Gene 151 (1994) 11–16). The present study shows that Escherichia coli harboring the blmA -carrying pUC plasmid overproduced β-lactamase, encoded by an ampicillin-resistance gene on the plasmid, when cultured in the presence of bleomycin, which suggests that bleomycin may act as an inducer (or an activator) for the expression of the specific gene in the presence of blmA . We constructed a vector, designated pMAB50, which senses bleomycin and produces a pigment, using blmA and a Streptomyces tyrosinase gene located under the control of β-lactamase promoter: E. coli harboring pMAB50 produced the melanin pigment in the presence of bleomycin-type antibiotics, suggesting that the transformed E. coli can be employed as a reporter organism to screen bleomycin analogues.     

DNA strand scission by neocarzinostatin: molecular recognition process responsible for site-specificity

A series of hexanucleotides possessing A-T, G-C, inosine (I)-C and 2-aminoadenine (ANH2)-T base pairs at 5'-side of the target thymine were prepared and their selectivity for C-5' and C4' oxidation in the NCS-mediated degradation was investigated. Quantitative product analysis indicated that preferential C5' oxidation of deoxyribose moiety of the target T occurs at -5'-AT- and 5'-IT- sites, whereas C5' and C4' oxidation occurs competitively at T of -5'-GT- and -5'-ANH2T- sites. Based on the experimental results, an intercalation model that permits competitive hydrogen abstraction from C5' and C4' of deoxyribose moiety has been proposed.