Photolytic Removal of Red Blood Cell Membranes Camouflaged on Nanoparticles for Enhanced Cellular Uptake and Combined Chemo-Photodynamic Inhibition of Cancer Cells.

Biomimetic therapeutics offer great potential for drug delivery that avoids immune recognition. However, the coated cell membrane usually hinders the cellular uptake of nanoparticles; thus, structure-changeable formulations have attracted increasing attention. Herein, we report photolytic pyropheophorbide a (PA)-inserted red blood cell (RBC) membrane-camouflaged curcumin dimeric prodrug (CUR2-TK)-poly(lactic-co-glycolic acid) (PLGA) nanoparticles [(CUR2-TK)-PLGA@RBC-PA] for enhanced cancer therapy. In these nanoparticles, the inner core was constructed using PLGA and loaded with our synthesized reactive oxygen species (ROS)-responsive cleavable curcumin dimeric prodrug (CUR2-TK). The nanoparticles generated ROS in response to the light irradiation attributed to the incorporated PA. The ROS further triggered the lysis of the cell membrane and exposed the nanoparticles for enhanced tumor cellular uptake, and the ROS also cleaved CUR2-TK for controlled CUR drug release. Moreover, the ROS performed photodynamic therapy (PDT). The chemotherapy and PDT produced a combined effect in the treatment of cancer cells, thus enhancing anticancer therapeutic efficacy.

Assembly and annotation of whole-genome sequence of Fusarium equiseti.

Fusarium equiseti is a plant pathogen with a wide range of hosts and diverse effects, including probiotic effects. However, the molecular mechanisms underlying these effects remain unclear, hindering its effective utilization. The final assembly included 16 scaffolds of contiguous sequence without gaps. The total sequence length was 40,776,005 bp, and the GC content of 48.01%. In total, we annotated the putative function of 13,134 genes, accounting for 94.97% of the candidate genes. We identified two and 23 candidate genes that are likely involved in the production of mycotoxins zearalenone and trichothecene, respectively. A comparative genomic analysis supported the high quality of the F. equiseti assembly. Our comprehensive analysis of whole-genome sequence will serve as a valuable resource for future studies of expression, regulation, function and evolution of the genes of F. equiseti as well as studies into disease prevention and control.

Microbial Nitrogen-Cycle Gene Abundance in Soil of Cropland Abandoned for Different Periods.

In Inner Mongolia, steppe grasslands face desertification or degradation because of human overuse and abandonment after inappropriate agricultural management. The soils in these abandoned croplands exist in heterogeneous environments characterized by widely fluctuating microbial growth. Quantitative polymerase chain reaction analysis of microbial genes encoding proteins involved in the nitrogen cycle was used to study Azotobacter species, nitrifiers, and denitrifiers in the soils from steppe grasslands and croplands abandoned for 2, 6, and 26 years. Except for nitrifying archaea and nitrous oxide-reducing bacteria, the relative genotypic abundance of microbial communities involved in nitrogen metabolism differed by approximately 2- to 10-fold between abandoned cropland and steppe grassland soils. Although nitrogen-cycle gene abundances varied with abandonment time, the abundance patterns of nitrogen-cycle genes separated distinctly into abandoned cropland versus light-grazing steppe grassland, despite the lack of any cultivation for over a quarter-century. Plant biomass and plant diversity exerted a significant effect on the abundance of microbial communities that mediate the nitrogen cycle (P < 0.002 and P < 0.03, respectively). The present study elucidates the ecology of bacteria that mediate the nitrogen cycle in recently abandoned croplands.

[Screening and functional properties of cholesterol-degrading lactic acid bacteria from Jiangshui].

OBJECTIVE: We intended to obtain and characterize lactic acid bacteria with high capacity of cholesterol-degrading. METHODS: We chose Jiangshui as the experimental material, screened lactic acid bacteria by the culture medium with high cholesterol, and studied other features of lactic acid bacteria like salt-tolerant, acid resistance, then identified the species of lactic acid bacteria by combining physiological and biochemical methods and 16S rDNA sequence. RESULTS: All lactic acid bacteria isolated had the capacity of cholesterol-degrading to some extent. There were 4 strains had high cholesterol-degrading rate (> 75%). Four strains were Lactococcus lactis subsp. lactis, two were Brevibacterium casei, and one was Lactococcus raffinolactis. CONCLUSION: Cholesterol-degrading lactic acid bacteria were screened from Jiangshui, with application potential for cholesterol degradation.

Molecular characterization of two Chinese isolates of Beet western yellows virus infecting sugar beet.

Beet western yellows virus (BWYV) has previously been reported as an agent of sugar beet yellowing disease in China. In this article, the complete genomic RNA sequences of two Chinese BWYV isolates infecting beet from Inner Mongolia (BWYV-IM) and Gansu (BWYV-GS) were determined and compared with three beet poleroviruses (BMYV, BChV and BWYV-US) and other non-beet-infecting poleroviruses. The genomes of the two isolates were 5,668 nt in length, and had almost the same genomic organization and characteristics as BWYV-US. The full length of BWYV-IM shared nucleotide sequence identities of 97.4, 86.6, 64.4 and 70.8% with BWYV-GS, BWYV-US, BChV and BMYV, respectively. Further sequence analysis indicated that the Chinese BWYV isolates were more closely related to BWYV-US; however, the identity of any gene product between the Chinese isolates and BWYV-US was <90%. Therefore, on the basis of genome sequence, we propose that these Chinese isolates are a distinct strain of BWYV that infect sugar beet. In addition, recombinant detection analysis revealed that BWYV-IM might be a recombinant virus.

Extracellular superoxide anion production contributes to the virulence of Xanthomonas oryzae pv. oryzae.

Endogenous superoxide anion production was determined by electron spin resonance in wild-type strains and avrXa7 mutants of Xanthomonas oryzae pv. oryzae. The localization of superoxide anion was carried out in the intra- and extra-cellular fractions. Results showed the presence of superoxide anion in multi-locations of X. oryzae pv. oryzae cells. The extracellular fraction was the major location of superoxide anion production. Furthermore, a positive relationship was shown between the levels of endogenous superoxide anion and the virulence of strains. These indubitable results suggested that the superoxide anion contributes to the virulence of X. oryzae pv. oryzae.

[Production and releasing sites of superoxide anion in phytopathogenic bacteria].

Many phytopathogenic bacteria were founded to release the superoxide anion (O2-) by themselves from different sites and the production of O2- was related to the pathogenicity of strains. The presences of O2- in cytomembrane, cell wall and filtrate were confirmed by chemical method and electron spin resonance (ESR). The results show that filtrate may be the primary site of O2- production due to its higher O2- generating activity either in the presence or the absence of DDC. Additional lines of evidence further suggested a regulatory mechanism of O2- production in phytopathogenic bacteria.

[O2-* burst of tobacco leaves triggered by Erwinia carotovora subsp. carotovora inoculation].

O(-.)(2) production based on chemical method by Ecc-treated intact tobacco leaves was observed. It showed a long-lasting one-phase course beginning 1 h and ending 14 h after Erwinia carotovora subsp. carotovora (Ecc) was inoculated. In Ecc-treated leaves, O(-.)(2) production rate of 3 h is 2 times of 1 h, and of 10 h it remains 1.7 times. It decreases rapidly between 10 h and 14 h, at 14 h it falls to the level before inoculation. This is a completely different course from the widely accepted two-phase course obtained from suspension-cultured cells. Electron spin resonance (ESR) spectrum of O(-.)(2) produced by intact tobacco leaves after Ecc inoculation 2 h and 6 h was also observed, the amplitude of 6 h is larger than of 2 h in Ecc-treated group. In the control group, there is no difference between the amplitude of 2 h and 6 h. This indicated that O(-.)(2) amount of Ecc-treated group is higher than of the control group, which is the same result as obtained through chemical method. The ESR spectrum of O(-.)(2) produced by chloroplasts and mitochondria from tobacco leaves after 2 h and 6 h after Ecc inoculation were observed. In chloroplast experiment, the amplitude of 6 h was larger than of 2 h in Ecc-treated group while it was the same in the control group. ESR spectrum of O(-.)(2) produced by mitochondria was proved to be a same result after a careful comparison, in spite of a greater difference between 2 h and 6 h in control group than chloroplast experiment. The fact that spectra of these two organelles were both synchronous with that of intact leaves implied that these two organelles possibly participated in cellular O(-.)(2) burst. Chloroplasts in the dark showed no ESR spectrum 2 h and 6 h after Ecc inoculation in Ecc-treated group as well as in the control group, indicating that O(-.)(2) in the chloroplast probably originated from the photosynthetic electron transport process.

[Field test and lab experiment on control efficacy of the pathogen of opium poppy mildew].

OBJECTIVE: To screen effectual fungicides for field control because of the seriousness of opium poppy mildew and importance of chemical control on plant diseases. METHOD: Seven fungicides were screened in Lab experiment and field test during 1996-1997. RESULT AND CONCLUSION: All of them and their different dosages were effective to control conidia of Peronospora arborescens. Among them, 72.2% propamocarb of 1203 and 902.5 ppm were the most effective both in Lab experiment and field test with efficacy 79.91% and 79.33% respectively in field test, and the efficacy of other fungicides was over 50%. Seven fungicides tested can be used to control nonsystematic symptom of opium poppy mildew.