Cytological changes during cell wall sac formation in mulberry idioblasts

Summary. When calcium carbonate crystals are formed in mulberry (Morus abla) idioblasts, they are deposited in newly formed cell wall sacs. The initial cytological events leading to cell wall sac formation were observed in the distal end of young idioblasts and tentatively categorized into four stages. The first indication of formation was the separation of the innermost cell wall layer from the cell wall, which is followed by the deposition of egg-shaped polysaccharide on the inner cell wall surface. The size of the deposit area increased, while the thickness of the cell wall significantly decreased during the next stage. Finally, the condensed cellulosic lamella was invaginated into the deposition area, resulting in the formation of an elongated cell wall sac. The internal cell wall sac was composed of numerous fibers with different morphologies. Application of gelatin-methenamine-silver staining allowed us to observe the spatial distribution of cellulosic polysaccharides as electron-dense images. Correspondence and reprints: Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan.     

Increased lipid rafts and accelerated lipopolysaccharide-induced tumor necrosis factor-alpha secretion in Abca1-deficient macrophages

Lipid rafts on the cell surface are believed to be very important as platforms for various cellular functions. The aim of this study was to know whether defective lipid efflux may influence lipid rafts on the cell surface and their related cellular functions. We investigated macrophages with defective lipid efflux from ATP binding cassette transporter A1-deficient (Abca1-KO) mice. Lipid rafts were evaluated by the following two novel probes: a biotinylated and protease (subtilisin Carlsberg)-nicked derivative of theta-toxin and a fluorescein ester of polyethylene glycol-derived cholesterol. Lipid rafts in Abca1-KO macrophages were increased, as demonstrated by both probes. Moreover, activities of nuclear factor kappaB, mRNA and intracellular distribution, and secretion of tumor necrosis factor-alpha (TNF-alpha) were examined after stimulation by lipopolysaccharides (LPSs). LPS-induced responses of the activation of nuclear factor kappaB and TNF-alpha were more prompt and accelerated in the Abca1-KO macrophages compared with wild-type macrophages. Modification of lipid rafts by cyclodextrin and nystatin corrected the abnormal response, suggesting an association between the increased lipid rafts and abnormal TNF-alpha secretion. We report here that Abca1-KO macrophages with defective lipid efflux exhibited increased lipid rafts on the cell surface and accelerated TNF-alpha secretion.     

The <Emphasis Type="Italic">COL1A1</Emphasis> gene and high myopia susceptibility in Japanese

The collagen type Ι alpha Ι (COL1A1) gene encodes the extracellular matrix component, collagen, and resides in candidate MYP5 for high myopia on the chromosome 17q22–q23.3. This locus has recently been implicated in playing an important role in the pathogenesis of experimental myopia. We investigated the association of disruptions of COL1A1 gene with high myopia by analyzing the frequency of ten SNPs in a Japanese population of 330 subjects with high myopia of −9.25 D or less and 330 randomized controls without high myopia. Two SNPs (rs2075555 and rs2269336) were significantly associated with high myopia (P < 0.05, Pc < 0.1). Two different haplotype blocks in COL1A1 were observed by the pair-wise linkage disequilibrium between the SNPs. The frequency of GGC/GGC diplotype constructed by the three SNPs (rs2075555, rs2269336, rs1107946) was significantly high (OR = 1.6) and associated with high myopia (P = 0.028, Pc< 0.084). Together our results provide the first evidence for COL1A1 as a gene associated with high myopia.     

Diversity of mycorrhizal fungi of terrestrial orchids: compatibility webs, brief encounters, lasting relationships and alien invasions

The diversity of mycorrhizal fungi associated with an introduced weed-like South African orchid (Disa bracteata) and a disturbance-intolerant, widespread, native West Australian orchid (Pyrorchis nigricans) were compared by molecular identification of the fungi isolated from single pelotons. Molecular identification revealed both orchids were associated with fungi from diverse groups in the Rhizoctonia complex with worldwide distribution. Symbiotic germination assays confirmed the majority of fungi isolated from pelotons were mycorrhizal and a factorial experiment uncovered complex webs of compatibility between six terrestrial orchids and 12 fungi from Australia and South Africa. Two weed-like (disturbance-tolerant rapidly spreading) orchids — D. bracteata and the indigenous Australian Microtis media, had the broadest webs of mycorrhizal fungi. In contrast, other native orchids had relatively small webs of fungi (Diuris magnifica and Thelymitra crinita), or germinated exclusively with their own fungus (Caladenia falcata and Pterostylis sanguinea). Orchids, such as D. bracteata and M. media, which form relationships with diverse webs of fungi, had apparent specificity that decreased with time, as some fungi had brief encounters with orchids that supported protocorm formation but not subsequent seedling growth. The interactions between orchid mycorrhizal fungi and their hosts are discussed.     

Carbohydrate-recognition domains of galectin-9 are involved in intermolecular interaction with galectin-9 itself and other members of the galectin family

Galectin-9 (Gal-9) is a tandem-repeat-type member of the galectin family associated with diverse biological processes, such as apoptosis, cell aggregation, and eosinophil chemoattraction. Although the detailed sugar-binding specificity of Gal-9 has been elucidated, molecular mechanisms that underlie these functions remain to be investigated. During the course of our binding study by affinity chromatography and surface plasmon resonance (SPR) analysis, we found that human Gal-9 interacts with immobilized Gal-9 in the protein-protein interaction mode. Interestingly, this intermolecular interaction strongly depended on the activity of the carbohydrate recognition domain (CRD), because the addition of potent saccharide inhibitors abolished the binding. The presence of multimers was also confirmed by Ferguson plot analysis of result of polyacrylamide gel electrophoresis and matrix-assisted laser-desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Moreover, this intermolecular interaction was observed between Gal-9 and other galectin members, such as Gal-3 and Gal-8, but not Gal-1. Because such properties have not been reported yet, they may explain an unidentified mechanism underlying the diverse functions of Gal-9.     

Novel sequence-responding fluorescent oligoDNA probe bearing a silylated pyrene molecule

A novel fluorescent phosphoramidite derivative of dimethylsilylated pyrene was prepared and incorporated into oligoDNA. The fluorescent oligoDNA exhibited marked fluorescent signal upon binding to the fully matched complementary DNA strand, however, the signal was strongly quenched in the single-stranded form as well as in the duplex having mismatched base pair at the terminus of the duplex-forming region.     

Restoration of cone vision in a mouse model of achromatopsia

Loss of cone function in the central retina is a pivotal event in the development of severe vision impairment for many prevalent blinding diseases. Complete achromatopsia is a genetic defect resulting in cone vision loss in 1 in 30,000 individuals. Using adeno-associated virus (AAV) gene therapy, we show that it is possible to target cones and rescue both the cone-mediated electroretinogram response and visual acuity in the Gnat2 ( cpfl3 ) mouse model of achromatopsia.