Arabidopsis histone methyltransferase SET DOMAIN GROUP2 is required for regulation of various hormone responsive genes

Histone modifications are known to play important roles in plant development through epigenetic regulation of gene expression. How these modifications regulate downstream targets in response to various environmental cues and developmental stimuli is still largely unknown. Here, we provide evidence that Arabidopsis histone H3K4 methyltransferase SET DOMAIN GROUP2 (SDG2) is required for full activation of hormone responsive genes upon hormone treatment. The pleiotropic phenotypes of sdg2 were closely related to those of auxin deficient mutants and RNA analysis revealed that expression of early hormone responsive genes was significantly reduced in sdg2-5. By ChIP analyses we found that H3K4 tri-methylations on chromatin region of hormone responsive genes such as SAUR27, KIN1 and GASA6 were enriched in WT upon hormone treatments whereas these enrichments were largely abolished in sdg2-5. After hormone treatment, chromatin regions of responsive genes that accumulated H3K4me3 in WT overlapped with those displaying decreased H3K4me3 levels in sdg2-5. Histone H3K4 di-methylation levels on tested genes were increased rather than decreased in sdg2-5, suggesting that SDG2 mediates transition of H3K4me2 to H3K4me3. Taken together, we conclude that the SDG2 activity is required to regulate the expression of hormone responsive genes via histone H3K4 tri-methylation.     

Combination of 1,4-naphthoquinone with benzothiazoles had selective algicidal effects against harmful algae

A series of naphthoquinone-benzothiazole conjugates were synthesized as algicides, and their efficacies against harmful algal blooming species, such as Chattonella marina, Heterosigma akashiwo and Cochlodinium polykrikoides, were examined. The introduction of substituted benzothiazole at the C2 position of 1,4-naphthoquinone (compounds 1–9) resulted in higher algicidal activity against C. polykrikoides than the C6 conjugates (compounds 10–20). On the other hand, of the C6 conjugates, compounds 11 and 12 exhibited better algicidal activity against H. akashiwo, C. marina, and C. polykrikoides than the C2 conjugates. Further structure-activity analysis indicated that a replacement of the methoxy groups with hydroxyl groups (compounds 21–26) decreased the algicidal activity significantly. Among the various synthetic naphthoquinonebezothiazole conjugates tested, compound 12 was found to affect the most significant decrease in the level of C. polykrikoides growth, with an IC₅₀ of 0.19 μM. Compound 11 was found to be the most potent inhibitor against H. akashiwo and C. polykrikoides, with IC₅₀ values of 0.32 and 0.12 μM, respectively. Overall, these results highlight a possible method for controlling and inhibiting red tide forming algae using NQ derivatives.     

Rice cell wall polysaccharides: Structure and biosynthesis

Rice is the most widely consumed staple food, and is cultivated worldwide to satisfy our daily caloric needs. Thus, extensive efforts on rice breeding and biotechnology have substantially focused on the development of elite cultivars with high yields and better grain quality, as well as enhanced resistance against biotic and abiotic stresses. Recently, it has been observed that rice is more than a just grain-producing crop. Carbon-rich materials of the rice cell wall polysaccharides from post-harvest wastes, including the straw and husk, have been converted into bioethanol and other invaluable, renewable materials. In order to maximize the utilization of cell wall-derived resources, it is imperative to understand cell wall chemistry and molecular mechanism underlying cell wall biosynthesis in rice. In the last decade, several approaches, including mutational genetics and the functional characterization of candidate genes, have been successful in isolating some of cell wall biosynthetic genes in rice, marking the first step forward in obtaining a complete understanding of rice cell wall biosynthesis, although the exact biochemical functions have not been conclusive. In this paper, we focus on integrating old and new information to provide an updated perspective in the cell wall formation of rice, highlighting the chemical structures and biosynthesis of rice cell wall polysaccharides.     

Enzyme-linked assay of cellulose-binding domain functions from Cellulomonas fimi on multi-well microtiter plate

Cellulose-binding domain (CBD) enriches cellulolytic enzymes on cellulosic surfaces and contributes to the catalytic efficiency by increasing enzyme-substrate complex formations. Thus, high affinity CBDs are essential for the development of efficient cellulose-degrading enzymes. Here, we present a microtiter plate-based assay system to measure the binding affinity of CBDs to cellulose. The assay uses a periplasmic alkaline phosphatase (AP) as a fusion reporter and its activity is detected using a fluorogenic substrate, 4-methylumbelliferyl phosphate. Lignocellulose discs of 6 mm in diameter were used as substrates in 96-well plate. As a result, the enzyme-linked assay detected the binding of CBDs on the cellulosic discs in a highly sensitive manner, detecting from 0.05 to 1.0 μg/mL of APCBD proteins, which is several hundred times more sensitive than conventional protein measurements. The proposed method was applied to compare the binding affinity of different CBDs from Cellulomonas fimi to lignocellulose discs.     

Evaluation of a novel pneumatic bioreactor system for culture of recombinant Chinese hamster ovary cells

Single use culture systems are a tool in research and biotechnology manufacturing processes and are employed in mammalian cell-based manufacturing processes. Recently, we characterized a novel bioreactor system developed by PBS Biotech. The Pneumatic Bioreactor System? (PBS) employs the Air-wheel?, which is a mixing device similar in structure to a water wheel but is driven by the buoyant force of gas bubbles. In this study, we investigated the physical properties of the PBS system, with which we performed biological tests. In 2 L PBS, the mixing times ranged from 6 (30 rpm, 0.175 vvm) to 15 sec (10 rpm, 0.025 vvm). The k_La value reached upto 7.66/h at 0.5 vvm, even without a microsparger, though this condition is not applicable for cell cultures. Also, when a 10 L PBS equipped with a microsparger was evaluated, a k_La value of upto approximately 20/h was obtained particularly in mild cell culture conditions. We performed cultivation of Chinese hamster ovary (CHO) cells in 2 and 10 L PBS prototypes. Results from the PBS were compared with those from an Erlenmeyer flask and conventional stirred tank type bioreactor (STR). The maximum cell density of 10.6 × 106 cells/mL obtained fromthe 2 L PBSwas about 2 times higher than that from the Erlenmeyer flask (5.6 × 10⁶ cells/mL) andwas similar to the STR (9.7 × 10⁶ cells/mL) when the CHO-S cells were cultured. These results support the general suitability of the PBS system using pneumatic mixing for suspension cell cultivation as a novel single-use bioreactor system.     

Stress response of plant H+-PPase-expressing transgenic Escherichia coli and Saccharomyces cerevisiae: a potentially useful mechanism for the development of stress-tolerant organisms

The simple proton-translocating inorganic pyrophosphatase (H⁺-PPase) found in plants and protists is an evolutionally conserved, essential enzyme that catalyzes the hydrolysis of pyrophosphate (PPi). Little is known about the functional contribution of H⁺-PPase to the cellular response to abiotic stresses, except its high salinity and drought stress. To investigate the role of H⁺-PPase during response to cellular stress, we isolated the cDNA of Arabidopsis thaliana H⁺-PPase (AVP1) and Oryza sativa H⁺-PPase (OVP1) and constructed transgenic Saccharomyces cerevisiae and Escherichia coli lines that express AVP1 and OVP1. In S. cerevisiae, the expression of a chimeric derivative of the AVP1 and OVP1 alleviated the phenotype associated with ipp2-deficient cells in the presence of high salinity (NaCl) and metal stressors (Cd, Mn, and Zn). In E. coli, AVP1 and OVP1 overexpression conferred enhanced tolerance to abiotic stresses, including heat shock and H₂O₂, as well as NaCl, Cd, Mn, Zn, Ca, and Al. Interestingly, AVP1 and OVP1 overexpression resulted in hypersensitivity to menadione and cobalt. These results demonstrate the cellular capacity of AVP1- and OVP1-expressing transgenic yeast and E. coli in response to physiological, abiotic stresses. Moreover, our results suggest new ways of engineering stress-tolerant plants that are capable of responding to climate change. Here, we provide an outline of an experimental system to examine the alternative roles of plant H⁺-PPase.     

Three new species of the genus Probles F?rster (Hymenoptera,Ichneumonidae, Tersilochinae) from?South Korea

Three closely related species of the genus Probles Förster, P. fulgida sp. n., P. korusa sp. n. and P. rukora sp. n., belong to the subgenus Euporizon Horstmann and differ from other Palearctic species of the genus by a combination of long and apically weakly sinuate ovipositor and short temple. These three species are assigned to a newly designated fulgida species-group, and a portion of the key for identification of this species-group is provided. Based on the shape of the ovipositor apex, the fulgida species-group resemble members of the subgenus Microdiaparsis Horstmann but are distinct in having a much shorter temple.