Ypts (yeast protein transports),also called as ras-associated binding GTPases (Rab), are the largest group of the small GTPases family, which have been extensively studied in model eukaryotic cells and play a pivotal role in membane trafficking, while this study showed potential regulation role of Ypts in fungi. One of Ypts, Ypt7 may be involved in fungal development and secondary metabolism, but the exact mechanism still exists a controversy. In current study, the functions of a Monascus ypt7 homologous gene (mrypt7) from Monascus ruber M7 was investigated by combination of gene-deletion (Δmrypt7), overexpression (M7::PtrpC-mrypt7) and transcriptome analysis. Results showed that the radial growth rate of Δmrypt7 was significantly slower than M. ruber M7, little conidia and ascospores can be observed in Δmrypt7, but the yield of intracellular secondary metabolites was dramatically increased. Simultaneously, the mrypt7 overexpression strain possessed similar capacity for sporulation and secondary metabolism observed in M. ruber M7. Transcriptome results further illustrated that mrypt7 could coordinate with numerous genes involved in the vegetative growth, conidiogenesis, secondary metabolism biosynthesis and transportation of M. ruber M7. Combined with the similar effect of Ypt7 homologs on other fungi, we propose that Ypt7 works more like a global regulatory factor in fungi. To our knowledge, it is the first time to investigate Ypt7 functions in Monascus. It could also improve the understanding of Ypt7 functions in fungi.

Aflatoxin B₁ (AFB₁) is a toxic secondary metabolic product, which threatens human and animal health. Antibody is a key factor for immunoassay against toxic stuff like AFB₁, and single-chain Fv antibody fragment (scFv) has become a popular format of genetically engineered antibody. In this study, four hybridoma cell lines against AFB₁ were obtained, and then scFvs 2E6 derived from hybridoma cell line 2E6 were constructed in different V_H/V_L orientations. Subsequently, scFvs 2E6 were expressed in E. coli BL21(DE3) mainly in the form of inclusion body. SDS-PAGE, Western blot and ELISA were employed to characterize scFvs 2E6. The results revealed that the yield of inclusion body of scFvs 2E6 in either V_H/V_L orientation was similar; however, only the scFv in V_H-linker-V_L orientation showed anti-AFB₁ bioactivity after refolding. The present study underscores the importance of choosing optimal V_H/V_L orientation for scFv construction, and scFv may be favorable for immunoassays in food industry.