Identification of tetracenomycin X from a marine-derived Saccharothrix sp. guided by genes sequence analysis / 药学学报

The crude extracts of the fermentation broth from a marine sediment-derived actinomycete strain, Saccharothrix sp. 10-10, showed significant antibacterial activities against drug-resistant pathogens. A genome-mining PCR-based experiment targeting the genes encoding key enzymes involved in the biosynthesis of secondary metabolites indicated that the strain 10-10 showed the potential to produce tetracenomycin-like compounds. Further chemical investigation of the cultures of this strain led to the identification of two antibiotics, including a tetracenomycin (Tcm) analogs, Tcm X (1), and a tomaymycin derivative, oxotomaymycin (2). Their structures were identified by spectroscopic data analysis, including UV, 1D-NMR, 2D-NMR and MS spectra. Tcm X (1) showed moderate antibacterial activities against a number of drug-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) pathogens, with the MIC values in the range of 32-64 microg x mL(-1). In addition, 1 also displayed significant cytotoxic activities against human cancer cell lines, including HL60 (leukemia), HepG2 (liver), and MCF-7 (breast) with the IC 50 values of 5.1, 9.7 and 18.0 micromol x L(-1), respectively. Guided by the PCR-based gene sequence analysis, Tcm X (1) and oxotomaymycin (2) were identified from the genus of Saccharothrix and their 13C NMR data were correctly assigned on the basis of 2D NMR spectroscopic data analysis for the first time.

Erythroleukemia Relapsing as Precursor B-cell Lymphoblastic Leukemia / 대한진단검사의학회지

AML relapsing as ALL has rarely been reported. We describe the case of a 62-yr-old man who was diagnosed with erythroleukemia with a complex karyotype and achieved complete hematologic and cytogenetic remission after induction chemotherapy. However, 4 months after the initial diagnosis, he showed relapse with blasts showing a different morphology and immunophenotype and was diagnosed with precursor B-cell ALL. The relapsing precursor B-cell ALL presented with the same leukemic clones as the primary erythroleukemia. Cytogenetic analysis of his bone marrow (BM) at the time of the primary erythroleukemia showed complex karyotypic abnormalities, including monosomy 5 and monosomy 7. At relapse, his BM showed reemergence of these leukemic clones of complex karyotypic abnormalities with clonal switch. To our knowledge, this is the first case of a lineage switch from erythroleukemia to ALL.

Physiological responses of phormidium fragile to naphthalene

The cyanobacterium, Phormidium fragile, was grown in culture media containing different concentrations of naphthalene. Tests were carried out under conditions allowing relatively free evaporation and volatilization of the hydrocarbon [open system] and in closed system in which hydrocarbon loss was minimized [closed system]. Under the former condition, the various naphthalene concentrations invariably affected dry weight gain of the organism. On the other hand, under the closed system, the dry weight decreased significantly. Under both cultural conditions, the algal protein content decreased, while the nucleic acids content was slightly affected by the type of cultural system. The alga accumulated larger amounts of carbohydrates under closed than open systems. Under the latter condition, naphthalene insignificantly affected MDH and stimulated GOT activity. On the contrary, under the closed system, MDH activity was stimulated by naphthalene, whereas GOT activity was hardly affected. Under both conditions, nitrate reductase was insensitive to naphthalene supplementation, while GPT activity increased at low concentrations, then dropped. There was a continuous increase in the different photosynthetic pigments with increased naphthalene concentrations. In the meantime, the lipid content of the alga was much higher under closed than open systems