Gold nanoparticles densely modified with single-stranded DNA (ssDNA–AuNPs) form aggregates with cross-linker ssDNAs via duplex formation. Alternatively, the ssDNA–AuNPs are spontaneously aggregated at high ionic strength in a non-cross-linking manner when complementary ssDNAs are added to form fully matched duplexes. Both aggregation modes are accompanied by a red-to-purple color change, which has been exploited in various bioassays. The current study compares the rapidity of color change between the cross-linking and non-cross-linking aggregation modes under identical conditions. When a small number of cross-linker/complementary DNAs are provided, the cross-linking mode exhibited more rapid color change than the non-cross-linking mode. Conversely, with a large number of the DNAs, the non-cross-linking aggregation occurred more rapidly than the cross-linking counterpart. This finding allows one to select a more appropriate aggregation mode for application of ssDNA–AuNPs to colorimetric assays under given conditions.

Previous studies showed that efforts to further elevate starch synthesis in rice (Oryza sativa) seeds overproducing ADP-glucose (ADPglc) were prevented by processes downstream of ADPglc synthesis. Here, we identified the major ADPglc transporter by studying the shrunken3 locus of the EM1093 rice line, which harbors a mutation in the BRITTLE1 (BT1) adenylate transporter (OsBt1) gene. Despite containing elevated ADPglc levels (approximately 10-fold) compared with the wild-type, EM1093 grains are small and shriveled due to the reduction in the amounts and size of starch granules. Increases in ADPglc levels in EM1093 were due to their poor uptake of ADP-[ 14 C]glc by amyloplasts. To assess the potential role of BT1 as a rate-determining step in starch biosynthesis, the maize ZmBt1 gene was overexpressed in the wild-type and the GlgC (CS8) transgenic line expressing a bacterial glgC-TM gene. ADPglc transport assays indicated that transgenic lines expressing ZmBT1 alone or combined with GlgC exhibited higher rates of transport (approximately 2-fold), with the GlgC (CS8) and GlgC/ZmBT1 (CS8/AT5) lines showing elevated ADPglc levels in amyloplasts. These increases, however, did not lead to further enhancement in seed weights even when these plant lines were grown under elevated CO 2 . Overall, our results indicate that rice lines with enhanced ADPglc synthesis and import into amyloplasts reveal additional barriers within the stroma that restrict maximum carbon flow into starch.Cereal grains contribute a significant portion of worldwide starch production. Unlike other plant tissue, starch biosynthesis in the endosperm storage organ of cereal grains is unique in its dependence on two ADP-Glc pyrophosphorylase (AGPase) isoforms Thorbjørnsen et al., 1996;Sikka et al., 2001), a major cytosolic enzyme and a minor plastidial one, to generate ADP-glucose (ADPglc), the sugar nucleotide utilized by starch synthases in the amyloplast (Cakir et al., 2015). The majority of ADPglc in cereal endosperm is generated in the cytosol from AGPase (Tuncel and Okita, 2013) as well as by Suc synthase (Tuncel and Okita, 2013;Bahaji et al., 2014) and subsequently transported into amyloplasts by the BRITTLE-1 (BT1) protein located at the plastid envelope (Cao et al., 1995;Shannon et al., 1998).The Bt1 gene, first identified in maize (Zea mays; Mangelsdorf, 1926) and isolated by Sullivan et al. (1991), encodes a major amyloplast membrane protein ranging from 39 to 44 kD (Cao et al., 1995). The BT1 protein and its homologs belong to the mitochondrial carrier family (Sullivan et al., 1991;Haferkamp, 2007), which has a diverse range of substrates (Patron et al., 2004;Leroch et al., 2005;Kirchberger et al., 2008). The assignment of BT1 protein as the ADPglc transporter in cereal endosperms was first proposed by Sullivan et al. (1991), and then it was characterized based on the increased ADPglc levels and reduced ADPglc import rate * Address correspondence to okita@wsu.edu and hikaru.satoh.682@ m.kyushu-u.ac.jp.The authors responsible for distribution ...

Commercial Li 2 SiO 3 (LSO) powder of 1−10 µm in diameter (Kishida Chemical Co. Ltd.) was pulverized by a planetary ball mill (300 rpm, 36 h) to obtain a nanosized Li 2 SiO 3 . Total

Nanoparticle (NP) arrays exhibit collective physical and chemical properties, which are potentially applicable to various nanodevices, such as data storage media and biosensors. In this Communication, a spontaneous method of constructing the 2D NP arrays from precursory 1D chains of DNA‐modified NPs is described. The single‐stranded (ss) DNA‐modified gold NPs are hybridized to a long repetitive ssDNA synthesized with rolling circle amplification to produce the precursory NP chains. Transmission electron microscopy reveals that the chains of fully matched double‐stranded (ds) DNA‐modified NPs undergo shrinkage and folding during evaporation to afford the 2D NP arrays. In particular, the chains of long dsDNA‐modified NPs with short interparticle spacing form the NP arrays with anisotropic interparticle spacing. The present approach could be useful for readily aligning NPs on the substrate surface.