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Rice blast is a devastating fungal disease resulting in major losses to rice crops. Owing to continuous acquisition of resistance by the causal fungus, several fungicide chemicals are no longer effective. Therefore, there is a need to identify natural components and develop new agents to control fungal pathogens. We previously demonstrated that the culture filtrate of Biscogniauxia sp. O821 inhibited infection behavior of Magnaporthe oryzae and subsequent blast lesion formation. In the present study, we isolated a new compound, (3aS,4aR,8aS,9aR)-3a-hydroxy-8a-methyl-3,5-dimethylenedecahydronaphto[2,3-b]furan-2(3H)-one (HDFO), from the culture filtrate of Biscogniauxia sp. O821 and determined its molecular weight as 248. The HDFO structure was determined by electrospray ionization-mass spectrometry and nuclear magnetic resonance spectroscopy after purification with column chromatography and high-performance liquid chromatography. The structure of this antifungal compound was similar to that of alantolactone and isoalantolactone. The growth inhibition zone against M. oryzae in presence of HDFO was observed at Rf 0.5–0.6 on a thin layer chromatography plate. HDFO inhibited conidial germination of M. oryzae in a dose-dependent manner (1–200 ppm). Furthermore, blast lesion formation was significantly suppressed by HDFO at over 5 ppm. These results suggest that HDFO from the culture filtrate of Biscogniauxia sp. O821 can protect rice from rice blast disease caused by M. oryzae. This is the first report that HDFO produced by Biscogniauxia sp. can serve as an antifungal compound against M. oryzae.

An ethyl acetate extract of a culture filtrate (ECF) from an unidentified fungal isolate O821 was evaluated for antifungal activity against the rice pathogen Magnaporthe oryzae. The O821-ECF significantly inhibited spore germination, appressorium formation, and mycelial growth of M. oryzae, and its antifungal activity was heat-stable. It also significantly suppressed the number and size of blast lesions. In an analysis of the ITS sequence of this isolate, it shared similarities with species of the fungus Biscogniauxia. These results suggest that isolate O821 of the genus Biscogniauxia produces a heat-stable antifungal compound(s) in its culture filtrate.

Microcell-mediated chromosome transfer (MMCT) technology enables a single and intact mammalian chromosome or megabase-sized chromosome fragments to be transferred from donor to recipient cells. The conventional MMCT method is performed immediately after the purification of microcells. The timing of the isolation of microcells and the preparation of recipient cells is very important. Thus, ready-made microcells can improve and simplify the process of MMCT. Here, we established a cryopreservation method to store microcells at −80 °C, and compared these cells with conventionally- (immediately-) prepared cells with respect to the efficiency of MMCT and the stability of a human artificial chromosome (HAC) transferred to human HT1080 cells. The HAC transfer in microcell hybrids was confirmed by FISH analysis. There was no significant difference between the two methods regarding chromosome transfer efficiency and the retention rate of HAC. Thus, cryopreservation of ready-to-use microcells provides an improved and simplified protocol for MMCT.

Background Human artificial chromosome (HAC) vectors have some unique characteristics as compared with conventional vectors, carrying large transgenes without size limitation, showing persistent expression of transgenes, and existing independently from host genome in cells. With these features, HACs are expected to be promising vectors for modifications of a variety of cell types. However, the method of introduction of HACs into target cells is confined to microcell-mediated chromosome transfer (MMCT), which is less efficient than other methods of vector introduction. Application of Measles Virus (MV) fusogenic proteins to MMCT instead of polyethylene glycol (PEG) has partly solved this drawback, whereas the tropism of MV fusogenic proteins is restricted to human CD46- or SLAM-positive cells. Results Here, we show that retargeting of microcell fusion by adding anti-Transferrin receptor (TfR) single chain antibodies (scFvs) to the extracellular C-terminus of the MV-H protein improves the efficiency of MV-MMCT to human fibroblasts which originally barely express both native MV receptors, and are therefore resistant to MV-MMCT. Efficacy of chimeric fusogenic proteins was evaluated by the evidence that the HAC, tagged with a drug-resistant gene and an EGFP gene, was transferred from CHO donor cells into human fibroblasts. Furthermore, it was demonstrated that no perturbation of either the HAC status or the functions of transgenes was observed on account of retargeted MV-MMCT when another HAC carrying four reprogramming factors (iHAC) was transferred into human fibroblasts. Conclusions Retargeted MV-MMCT using chimeric H protein with scFvs succeeded in extending the cell spectrum for gene transfer via HAC vectors. Therefore, this technology could facilitate the systematic cell engineering by HACs. Electronic supplementary material The online version of this article (doi:10.1186/s12896-015-0142-z) contains supplementary material, which is available to authorized users.