红树林内生真菌研究进展

红树林作为一种特殊的植物群落具有丰富的内生真菌资源,目前已分离鉴定的红树林真菌超过200种,成为海洋真菌的第二大类群,已报道的红树林内生真菌主要类群是链格孢霉(Alternaria)、曲霉(Aspergillus)、芽枝霉(Cladosporium)、炭疽菌(Colletotrichum)、镰孢霉(Fusarium)、拟青霉(Paecilomyces)、拟盘多毛孢(Pestalotiopsis)、青霉(Penicillium)、茎点霉(Phoma)、拟茎点霉(Phomopsis)、叶点霉(Phyllosticta)和木霉(Trichoderma)等.大部分红树林内生真菌具有较宽的宿主范围,极少数只有单一的宿主,不同红树林植物的内生真菌区系及优势种群有很大差异.红树林内生真菌的定殖因宿主植物不同部位、植株的年龄及季节和环境的变化明显不同.红树林内生真菌能产生多种代谢产物,具有抗菌、抗肿瘤等药用价值.红树林植物内生真菌的研究和开发具有重要意义.本文综述了红树林内生真菌的生物多样性及其分布、生物学功能和次生代谢产物等方面的研究进展.     

Comparison of antioxidative capacities and inhibitory effects on cholesterol biosynthesis of quercetin and potential metabolites

The flavonol quercetin is known to be rapidly metabolized after ingestion by enterocytes and bacteria in the intestinal tract which may influence the biological, e.g. antioxidative potency of this compound. Therefore, quercetin and several of its possible metabolites were compared with regard to their antioxidant activity and their capacity to inhibit hepatocellular cholesterol biosynthesis. Using the 2,2,-diphenylpicrylhydrazyl radical scavenger assay, all compounds with an ortho diphenolic structure acted as strong antioxidants. In contrast, in a cellular assay focusing on lipid peroxidation in cultured rat hepatocytes challenged with tert.-butylhydroperoxide only the lipophilic compounds quercetin and 3,4-dihydroxytoluene were active. Concerning the inhibition of cholesterol biosynthesis, 3,4-dihydroxytoluene surprisingly mimicked the effect of quercetin in primary rat hepatocytes, but much less so in HepG2 cells. All other metabolites were almost ineffective in both cell types. These results suggest that some of the biological functions of flavonoids detectable by in vitro assays may persist in vivo as long as comparably potent metabolites are systemically present.     

New γ-pyranone and nucleoside derivatives from Penicillium sp.

Peniopyranone (1) and 2-methoxyl-β-l-Arabinofuroside uracil (2), together with six known compounds were isolated from the broth of Penicillium sp. (NO. 64). And their structures were established by comprehensive analysis of NMR, MS and CD spectra, the absolute configurations of Peniopyranone (1) were determined as 7S, 8S and 9R by calculating its ECD. The eight obtained metabolites were subjected to evaluate the preliminary cytotoxic activities to four cancer cell lines, but they showed no significant data with IC₅₀ > 50 μmol/mL. The results of acetylcholinesterase inhibiting assay showed that peniopyranone (1) displayed the inhibition activity to acetylcholinesterase with IC₅₀ at 15.2 μmol/mL.     

Study of the efficacy of Aureobasidium strains belonging to three different species: A. pullulans,A. subglaciale and A. melanogenum against Botrytis cinerea of tomato

The difference in antagonistic activity against the causal agent of grey mould (Botrytis cinerea) of tomato between Aureobasidium strains belonging to three different species, namely A. pullulans, A. melanogenum and A. subglaciale, was evaluated by in vitro and in vivo assays. In the yeast–pathogen direct interaction experiment, all the strains significantly reduced B. cinerea growth, with A. melanogenum the least efficient species (17.8% of reduction) compared to A. pullulans and subglaciale (22 and 27.8%). The non-volatile metabolites produced by all three species reduced mycelial growth between 95 and 100%. These metabolites were characterised by FT-IR spectroscopy as polysaccharides, lytic enzymes, siderophores and antibiotics. The inhibitory effect of Aureobasidium strains on pathogenic enzymes such as xylanase, polygalacturonase and pectinase was measured showing A. pullulans strains as capable of strong inhibition of xylanase, an enzyme directly related to the virulence of necrotrophic pathogens such as B. cinerea. Our data demonstrate that the different species of Aureobasidium isolated from a range of non-conventional environments exerted variable efficacy against B. cinerea, with A. pullulans as the most active species followed by A. subglaciale and A. melanogenum as ineffective and not suitable for biocontrol applications.     

Augmentation of systemic resistance and secondary metabolites by chitinolytic microbes in Withania somnifera against Meloidogyne incognita

Ashwagandha (Withania somnifera L. Dunal), a therapeutically imperative herb is known for its useful steroidal lactones (withanolide and withaferin) and acyl steryl glycosides. The plant is a highly susceptible host for the plant parasitic nematode, Meloidogyne incognita. Selected chitinolytic microbes, namely Cellulosimicrobium cellulans MTN13, Flavobacterium johnsoniae MTN 20, Chitiniphilus sp. MTN22 and Streptomyces sp. MTN14, alone and in combination for M. incognita management and enhancement of secondary metabolites in W. somnifera cv. Poshita were evaluated. A significant enhancement in biomass yield (1.9-fold) and disease diminution (2.7-fold) was found in the dual microbial treatment Streptomyces sp. and Chitiniphilus sp. with respect to the untreated inoculated control plants. A significant augmentation (2.7- and 2.0-fold, respectively) in withanolide A and withaferin A was also found in the same treatment. The studies revealed increment of defence variables 1.1- to 1.3-fold and 1.6- to 2.1-fold in single- and dual-microbe treatments, respectively, than the untreated inoculated plants. The stimulation of the phenylpropanoid pathway and phenolics accumulation was the maximum at 5 days post inoculation (dpi), whereas antioxidant enzymes activities were the highest at 7?dpi. The results thus highlight a possible new function of chitinolytic microbes alone and in combinations that can effectively manage M. incognita-induced stress along with enhanced active molecules of W. somnifera.     

Metabolomics evidences plasma and serum biomarkers differentiating two heavy pig breeds

In pigs, many production traits are known to vary among breeds or lines. These traits can be considered end phenotypes or external traits as they are the final results of complex biological interactions and processes whose fine biological mechanisms are still largely unknown. This study was designed to compare plasma and serum metabolomic profiles between animals of two heavy pig breeds (12 Italian Large White and 12 Italian Duroc), testing indirectly the hypothesis that different genetic backgrounds might be the determining factors of differences observed on the level of metabolites in the analyzed biofluids between breeds. We used a targeted metabolomic approach based on mass spectrometric detection of about 180 metabolites and applied a statistical validation pipeline to identify differences in the metabolomic profiles of the two heavy pig breeds. Blood samples were collected after jugulation at the slaughterhouse and prepared for metabolomics analysis that was carried out using the Biocrates AbsoluteIDQ p180 Kit, covering five different biochemical classes: glycerophospholipids, amino acids, biogenic amines, hexoses and acylcarnitines. A statistical pipeline that included the selection of the most relevant metabolites differentiating the two breeds by sparse Partial Least Squares Discriminant Analysis (sPLS-DA) was coupled with a stability test and significance test determined with leave one out and permutation procedures. sPLS-DA plots clearly separated the pigs of the two investigated breeds. A few metabolites (a total of five metabolites considering the two biofluids) involved in key metabolic pathways largely contributed to these differences between breeds. In particular, a higher level of the sphingomyelins SM (OH) C14:1 (both in plasma and serum), SM (OH) C16:1 (in serum) and SM C16:0 (in serum) were observed in Italian Duroc than in Italian Large White pigs and the inverse was for the biogenic amine kynurenine (in plasma). The level of another biogenic amine (acetylornithine) was higher in Italian Large White than in Italian Duroc pigs in both analysed biofluids. These results provided biomarkers that could be important to understand the biological differences between these two heavy pig breeds. In particular, according to the functional role played by sphingomyelins in obesity-induced inflammatory responses, it could be possible to speculate that a higher level of sphingomyelins in Italian Duroc might be related to the higher interrmuscular fat deposition of this breed compared with the Italian Large White. Additional studies will be needed to evaluate the relevance of these biomarkers for practical applications in pig breeding and nutrition.     

New oxylipins produced at the end of a diatom bloom and their effects on copepod reproductive success and gene expression levels

Diatoms are dominant photosynthetic organisms in the world's oceans and are considered essential in the transfer of energy to higher trophic levels. However, these unicellular organisms produce secondary metabolites deriving from the oxidation of fatty acids, collectively termed oxylipins, with negative effects on predators, such as copepods, that feed on them (e.g. reduction in survival, egg production and hatching success) and, indirectly, on higher trophic levels. Here, a multidisciplinary study (oxylipin measurements, copepod fitness, gene expression analyses, chlorophyll distribution, phytoplankton composition, physico-chemical characteristics) was carried out at the end of the spring diatom bloom in April 2011 in the Northern Adriatic Sea (Mediterranean Sea) in order to deeply investigate copepod–diatom interactions, chemical communication and response pathways. The results show that the transect with the lowest phytoplankton abundance had the lowest copepod egg production and hatching success, but the highest oxylipin concentrations. In addition, copepods in both the analyzed transects showed increased expression levels of key stress-related genes (e.g. heat-shock proteins, catalase, glutathione S-transferase, aldehyde dehydrogenase) compared to control laboratory conditions where copepods were fed with the dinoflagellate Prorocentrum minimum which does not produce any oxylipins. New oxylipins that have never been reported before for microalgae are described for the first time, giving new insights into the complex nature of plant–animal signaling and communication pathways at sea. This is also the first study providing insights on the copepod response during a diatom bloom at the molecular level.