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The biggest challenge in anabolism research is to improve the stability and safety of microbial metabolite production on an industrial scale. One class of metabolites, avermectins, are produced by Streptomyces avermitilis. In this study, an avermectin B1a-high-producing mutant was produced using heavy ion mutagenesis and selected based on LTQ-MS and HPLC-UV method. The mutants ZJAV-Y-147 and ZJAV-Y-HS, obtained after subjecting the spores of S. avermitilis to 70 Gy of 12C6+ heavy ion irradiation, were found to best improve the avermectin B1a production (4822.23 μg/mL and 4632.17 μg/mL, respectively). These two mutants' yielded of avermectin B1a were 2-fold high than the original strains. The DNA of the original and mutant strains were analyzed by RAPD technique with four random primers after irradiated with ion beam irradiation. The results show that different high-titer S. avermitilis strains contain different genetic modifications. In addition, the mutation position, mutation type and sequence context of all mutations of aveC, aveD, aveI, aveR gene in two mutants S.avermitilis were researched, and the production of avermectin B1a and its analogues of wild-type and mutants were analyzed by fermenting 240 h, which was suggested that the partial base deletion of aveI gene may be the key sites for increasing avermectin B1a production after the 12C6+-ion irradiation. All these modifications promote increased avermectin biosynthesis, leading to multiple high-titer S. avermitilis strains. The results demonstrate that this is an effective approach to engineer S. avermitilis as a host for the biological production of commercial analogs.

Total synthesis of the originally proposed chrysamide B (2) is described, which features a convergent assembly of the chiral piperazine core and epoxy-acid. Mismatched spectroscopic data for the synthetic sample compared to that for the isolate led us to propose the revised structure 3 based on biosynthetic considerations. In a further antibacterial assay, chrysamide B and its diastereomer 2 exhibited different activities.

The biggest challenge in anabolism research is to improve the stability and safety of microbial metabolite production on an industrial scale. One class of metabolites, avermectins, are produced by Streptomyces avermitilis. In this study, an avermectin B1a‐high‐producing mutant was produced using heavy ion mutagenesis and selected based on LTQ‐MS and HPLC‐UV method. The mutants ZJAV‐Y‐147 and ZJAV‐Y‐HS, obtained after subjecting the spores of S. avermitilis to 70 Gy of (12)C(6+) heavy ion irradiation, were found to best improve the avermectin B1a production (4822.23 μg/mL and 4632.17 μg/mL, respectively). These two mutants’ yielded of avermectin B1a were 2‐fold high than the original strains. The DNA of the original and mutant strains were analyzed by RAPD technique with four random primers after irradiated with ion beam irradiation. The results show that different high‐titer S. avermitilis strains contain different genetic modifications. In addition, the mutation position, mutation type and sequence context of all mutations of aveC, aveD, aveI, aveR gene in two mutants S.avermitilis were researched, and the production of avermectin B1a and its analogues of wild‐type and mutants were analyzed by fermenting 240 h, which was suggested that the partial base deletion of aveI gene may be the key sites for increasing avermectin B1a production after the (12)C(6+)‐ion irradiation. All these modifications promote increased avermectin biosynthesis, leading to multiple high‐titer S. avermitilis strains. The results demonstrate that this is an effective approach to engineer S. avermitilis as a host for the biological production of commercial analogs.

Raman tweezers have been used to study single blood cells in vivo without requiring invasive procedures. In the present study, we use optical tweezers to capture single blood cells (RBCs) in the microvessel of a mouse ear. Without the use of any invasive procedures, we were able to obtain the Raman spectra of single red blood cells from a mouse ear. An analysis of these spectra indicated that RBCs in arterioles are oxygenated, while those in the capillaries of venules are deoxygenated, those in vitro are similar to that in venules. In addition, hemoglobin in vivo was observed to be more concentrated than that in vitro. By studying the change of the band at 1604 cm−1, we concluded that the pH in arterioles is higher than that in venules. The information gained from the single RBCs in vivo is important for the understanding of the reaction of RBCs to changes in their environment and may have many applications in the diagnosis and treatment of red blood cell disorders.