Antibacterial metabolites from the beetle-associated fungus Penicillium chrysogenum.

The antibacterial secondary metabolites of the fungus Penicillium chrysogenum associated with the beetle Aspongopus chinensis were investigated through chromatographic fractionation methods of ethyl acetate extracts of the fungal cultures. Five compounds were isolated, and their structures were determined as emodin, 4-(methoxymethyl)benzoic acid, isoochracinic acid, secalonic acid D, and dicerandrol A using mass spectroscopy and nuclear magnetic resonance spectroscopic analyses. Emodin exhibited strong antimicrobial activity, especially against Staphylococcus aureus even when growing on cooked pork, with a minimal inhibitory concentration (MIC) of 6.3 µg/mL. Dimeric tetrahydroxanthones, such as secalonic acid D and dicerandrol A, also exhibited potent activity, with MIC values ranging from 9.5 to 28.5 µg/mL. In summary, P. chrysogenum was isolated as a symbiotic fungus of the beetle A. chinensis for the first time and this strain could generate antibacterial secondary metabolites, which could potently inhibit gram-positive bacteria growth in vitro.

Transmission dynamics of cholera with hyperinfectious and hypoinfectious vibrios: mathematical modelling and control strategies.

Cholera is a common infectious disease caused by Vibrio cholerae, which has different infectivity. In this paper, we propose a cholera model with hyperinfectious and hypoinfectious vibrios, in which both human-to-human and environment-to-human transmissions are considered. By analyzing the characteristic equations, the local stability of disease-free and endemic equilibria is established. By using Lyapunov functionals and LaSalle's invariance principle, it is verified that the global threshold dynamics of the model can be completely determined by the basic reproduction number. Numerical simulations are carried out to illustrate the corresponding theoretical results and describe the cholera outbreak in Haiti. The study of optimal control helps us seek cost-effective solutions of time-dependent control strategies against cholera outbreaks, which shows that control strategies, such as vaccination and sanitation, should be taken at the very beginning of the outbreak and become less necessary after a certain period.

Qualitative and quantitative analysis of chemical constituents of Ptychopetalum olacoides Benth.

Ptychopetalum olacoides is a folk medicinal plant for health care in market, especially in Brazil. Fourteen known compounds were isolated from P. olacoides and their chemical structures were elucidated by extensive spectroscopic data, including 1D NMR, 2D NMR, UV, IR and HR-ESI-MS. The 14 known compounds were identified as N-trans-feruloyl-3,5-dihydroxyindolin-2-one (1), magnoflorine (2), menisperine (3), 4-coumaroylserotonin (4), moschamine (5), luteolin (6), 4'-methoxyluteolin (7), 3-methoxyluteolin (8), 3, 7-dimethoxyluteolin (9), caffeic acid (10), ferulic acid (11), vanillic acid (12), syringic acid (13) and ginsenoside Re (14). To our knowledge, compounds (1-6, 13-14) were isolated from the plant for the first time. Additionally, quantitative analysis results indicated that calibration equations of compounds (1-3, 6, 9, 11-13) exhibited good linear regressions within the test ranges (R2 ≥ 0.9990) and magnoflorine and menisperine were the major constituents in the barks of P. olacoides. The contents of magnoflorine and menisperine accounted for 75.96% of all analytes. However, the content of phenolic components was smaller and the highest content was no more than 1.04 mg/g. Collectively, these results suggested that alkaloids are the dominant substances in P. olacoides, which can make a difference for the quality control and further use of P. olacoides.

Transcriptome sequencing and analysis of rubber tree (Hevea brasiliensis Muell.) to discover putative genes associated with tapping panel dryness (TPD).

BACKGROUND: Tapping panel dryness (TPD) involves in the partial or complete cessation of latex flow thus seriously affect latex production in rubber tree (Hevea brasiliensis). Numerous studies have been conducted to define its origin and nature, but the molecular nature and mechanism of TPD occurrence remains unknown. This study is committed to de novo sequencing and comparative analysis of the transcriptomes of healthy (H) and TPD-affected (T) rubber trees to identify the genes and pathways related to the TPD. RESULTS: Total raw reads of 34,632,012 and 35,913,020 bp were obtained from H and T library, respectively using Illumina Hiseq 2000 sequencing technology. De novo assemblies yielded 141,456 and 169,285 contigs, and 96,070 and 112,243 unigenes from H and T library, respectively. Among 73597 genes, 22577 genes were identified as differential expressed genes between H and T library via comparative transcript profiling. A majority of genes involved in natural rubber biosynthesis and jasmonate synthesis with most potential relevance in TPD occurrence were found to be differentially expressed. CONCLUSIONS: In TPD-affected trees, the expression of most genes related to the latex biosynthesis and jasmonate synthesis was severely inhibited and is probably the direct cause of the TPD. These new de novo transcriptome data sets provide a significant resource for the discovery of genes related to TPD and improve our understanding of the occurrence and maintainace of TPD.