Hepatitis C virus (HCV) infection causes chronic liver diseases and is a global public health problem. Detailed analyses of HCV have been hampered by the lack of viral culture systems. Subgenomic replicons of the JFH1 genotype 2a strain cloned from an individual with fulminant hepatitis replicate efficiently in cell culture. Here we show that the JFH1 genome replicates efficiently and supports secretion of viral particles after transfection into a human hepatoma cell line (Huh7). Particles have a density of about 1.15–1.17 g/ml and a spherical morphology with an average diameter of about 55 nm. Secreted virus is infectious for Huh7 cells and infectivity can be neutralized by CD81-specific antibodies and by immunoglobulins from chronically infected individuals. The cell culture–generated HCV is infectious for chimpanzee. This system provides a powerful tool for studying the viral life cycle and developing antiviral strategies.

Production of infectious hepatitis C virus in tissue culture from a cloned viral genome

Organic Chemistry By Dr. I. L. Finar. Vol. 2: Stereochemistry and the Chemistry of Natural Products. Pp. xi + 733. (London and New York: Longmans, Green and Co., Ltd., 1956.) 40s. net.

Advanced Organic Chemistry

There is growing recognition that many phenolic secondary metabolites present in foodstuffs may possibly exert beneficial effects on human health. This may to some degree be mediated via antioxidant actions, but a range of more specific pharmacological effects have also been proposed. Given this background, there may be favourable consequences for the general health of Western populations as a result of optimising the phenolic content of the diet. This paper reviews what is known of the function of phenolics both in the plant and in man. It also describes current understanding of the biosynthesis of phenolics in plants, with emphasis on where potential controlling steps may exist. Finally, advances in identification and isolation of the genes coding for phenolic biosynthetic enzymes or regulatory proteins are also summarised. Taken together, this information provides a basis for attempts to modify and optimise the phenolic content of food crops, using either conventional plant breeding along with manipulation of agronomic practices, or else the more targeted approaches of modern molecular biology.



© 2000 Society of Chemical Industry

Phenols in the plant and in man. The potential for possible nutritional enhancement of the diet by modifying the phenols content or profile

Plant cell walls represent the most abundant renewable resource on this planet. Despite their great abundance, only 2% of this resource is currently used by humans. Hence, research into the feasibility of using plant cell walls in the production of cost-effective biofuels is desirable. The main bottleneck for using wall materials is the recalcitrance of walls to efficient degradation into fermentable sugars. Manipulation of the wall polysaccharide biosynthetic machinery or addition of wall structure-altering agents should make it possible to tailor wall composition and architecture to enhance sugar yields upon wall digestion for biofuel fermentation. Study of the biosynthetic machinery and its regulation is still in its infancy and represents a major scientific and technical research challenge. Of course, any change in wall structure to accommodate cost-efficient biofuel production may have detrimental effects on plant growth and development due to the diverse roles of walls in the life of a plant. However, the diversity and abundance of wall structures present in the plant kingdom gives hope that this challenge can be met.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2008.03463.x

Cell‐wall carbohydrates and their modification as a resource for biofuels

Because lignin limits the use of wood for fiber, chemical, and energy production, strategies for its downregulation are of considerable interest. We have produced transgenic aspen (Populus tremuloides Michx.) trees in which expression of a lignin biosynthetic pathway gene Pt4CL1 encoding 4-coumarate:coenzyme A ligase (4CL) has been downregulated by antisense inhibition. Trees with suppressed Pt4CL1 expression exhibited up to a 45% reduction of lignin, but this was compensated for by a 15% increase in cellulose. As a result, the total lignin–cellulose mass remained essentially unchanged. Leaf, root, and stem growth were substantially enhanced, and structural integrity was maintained both at the cellular and whole-plant levels in the transgenic lines. Our results indicate that lignin and cellulose deposition could be regulated in a compensatory fashion, which may contribute to metabolic flexibility and a growth advantage to sustain the long-term structural integrity of woody perennials.

Biotechnology on genetic control of lignin biosynthesis in trees -Repression of lignin biosynthesis promotes cellulose accumulation and growth in transgenic trees-

Asparagus officinalis hinokiresinol synthase (HRS) is composed of two subunits, HRSα and HRSβ. Individually, each subunit forms (E)-hinokiresinol (EHR) from 4-coumaryl 4-coumarate, whereas a mixture of both subunits forms (Z)-hinokiresinol (ZHR) from the same substrate. In this study, we analyzed the enantiomeric compositions of ZHR and EHR formed after incubation of 4-coumaryl 4-coumarate with recombinant subunit proteins, recHRSα and/or recHRSβ, and with naturally occurring A. officinalis ZHR. The enantiomeric composition of ZHR formed by the mixture of recHRSα and recHRSβ was (+)-100% enantiomer excess (e.e.), identical to that of A. officinalis ZHR. In contrast, the enantiomeric compositions of EHR formed by recHRSα and recHRSβ, individually, were (−)-20.6 and (−)-9.0% e.e., respectively. These results clearly demonstrate that the subunit composition of A. officinalis HRS controls not only cis/trans isomerism but also enantioselectivity in hinokiresinol formation.

Subunit composition of hinokiresinol synthase controls enantiomeric selectivity in hinokiresinol formation.

A method for the accurate evaluation of the organic carbon (OC) content of phytoplankton by soft X-ray microscopy (XM) was developed and applied to the picophytoplankton Synechococcus sp., whose cells are covered by extracellular polysaccharides (EPS). Based on the X-ray absorption coefficients and gray levels of the XM images, the OC content of EPS-covered cells of Synechococcus sp. (0.39–0.47 pg/cell) was found to be 2.0–2.4 times larger than that of EPS-removed cells (0.20 pg/cell). These findings suggest that soft XM could be a useful tool for evaluating the OC content of picophytoplankton and EPS without pretreatment steps.

Estimation of Organic Carbon Content of the Cyanobacterium Synechococcus sp. by Soft X-ray Microscopy

Characterization of cell wall phenylpropanoids of grass bioenergy plants and characterization of ubiquitin ligase involved in secondary cell wall formation in Arabidopsis Author(s) Yamamura, Masaomi; Suzuki, Shiro; Umezawa, Toshiaki Citation Sustainable humanosphere : bulletin of Research Institute for Sustainable Humanosphere Kyoto University (2014), 10: 3-3 Issue Date 2014-10-20 URL http://hdl.handle.net/2433/196703 Right Type Departmental Bulletin Paper Textversion publisher

Characterization of cell wall phenylpropanoids of grass bioenergy plants and characterization of ubiquitin ligase involved in secondary cell wall formation in Arabidopsis

The present invention provides an enzyme having an activity of transferring a methyl group to lignans (a lignan methylation activity) (e.g., a protein comprising the amino acid sequence of SEQ ID NO:2 or variants thereof); a gene encoding the enzyme (e.g., a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1 or variants thereof); a method for producing methylated lignans using the gene; and so on.

Gene encoding lignan methyltransferase, and use thereof

O-Methyltransferases (OMTs) play important roles in antitumor lignan biosynthesis. To date, six OMTs catalyzing the methylation of dibenzylbutyrolactone lignans as biosynthetic precursors of antitumor lignans have been identified. However, there is still no systematic understanding of the diversity and regularity of the biosynthetic mechanisms among various plant lineages. Herein, we report the characterization of two OMTs from Anthriscus sylvestris and Thujopsis dolabrata var. hondae [designated as AsSecoNorYatein (SNY) OMT and TdSNYOMT] together with the six known OMTs to evaluate their diversity and regularity. Although AsSNYOMT and TdSNYOMT accept 5-O-methylthujaplicatin and 4-O-demethylyatein as substrates, phylogenetic analysis indicated that these two OMTs shared low amino acid sequence identity, 33.8%, indicating a signature of parallel evolution. The OMTs and the six previously identified OMTs were found to be diverse in terms of their substrate specificity, regioselectivity, and amino acid sequence identity, indicating independent evolution in each plant species. Meanwhile, two-entropy analysis detected four amino acid residues as being specifically acquired by dibenzylbutyrolactone lignan OMTs. Site-directed mutation of AsSNYOMT indicated that two of them contributed specifically to 5-O-methylthujaplicatin methylation. The results provide a new example of parallel evolution and the diversity and regularity of OMTs in plant secondary (specialized) metabolism.

Two O-methyltransferases from Phylogenetically Unrelated Cow Parsley (Anthriscus sylvestris) and Hinoki-asunaro (Thujopsis dolabrata var. hondae) as a Signature of Lineage-specific Evolution in Lignan Biosynthesis†.

Shiro Suzuki

Papers

Subunit composition of hinokiresinol synthase controls enantiomeric selectivity in hinokiresinol formation.

Estimation of Organic Carbon Content of the Cyanobacterium Synechococcus sp. by Soft X-ray Microscopy

Characterization of cell wall phenylpropanoids of grass bioenergy plants and characterization of ubiquitin ligase involved in secondary cell wall formation in Arabidopsis

Gene encoding lignan methyltransferase, and use thereof

Two O-methyltransferases from Phylogenetically Unrelated Cow Parsley (Anthriscus sylvestris) and Hinoki-asunaro (Thujopsis dolabrata var. hondae) as a Signature of Lineage-specific Evolution in Lignan Biosynthesis†.