A Theoretical Model of Jigsaw-Puzzle Pattern Formation by Plant Leaf Epidermal Cells

Plant leaf epidermal cells exhibit a jigsaw puzzle–like pattern that is generated by interdigitation of the cell wall during leaf development. The contribution of two ROP GTPases, ROP2 and ROP6, to the cytoskeletal dynamics that regulate epidermal cell wall interdigitation has already been examined; however, how interactions between these molecules result in pattern formation remains to be elucidated. Here, we propose a simple interface equation model that incorporates both the cell wall remodeling activity of ROP GTPases and the diffusible signaling molecules by which they are regulated. This model successfully reproduces pattern formation observed in vivo, and explains the counterintuitive experimental results of decreased cellulose production and increased thickness. Our model also reproduces the dynamics of three-way cell wall junctions. Therefore, this model provides a possible mechanism for cell wall interdigitation formation in vivo.     

Intervention of somatic mutational events in vivo by a germline defect at the adenine phosphoribosyltransferase locus

Both germline and somatic mutations are known to affect phenotypes of human cells in vivo. In previous studies, we cloned mutant peripheral blood T cells from germline heterozygous humans for adenine phosphoribosyltransferase (APRT) (EC 2.4.2.7) deficiency and found that approximately 1.3 × 10^–4 peripheral T cells had undergone in vivo somatic mutations. Loss of heterozygosity (LOH) was the major cause of the mutations at the APRT locus since approximately 80% of the mutant T cell clones exhibited loss of normal alleles. In the present study, we identified three heterozygous individuals for APRT deficiency (representing two separate families), in whom none of the somatic mutant cells exhibited LOH at the APRT locus. The germline mutant APRT alleles of these heterozygotes from two unrelated families had the same gross DNA abnormalities detectable by Southern blotting. None of the germline mutant APRT alleles so far reported had such gross DNA abnormalities. The data suggest that the germline mutation unique to these heterozygous individuals is associated with the abrogation of LOH in somatic cells. The absence of LOH at a different locus has already been reported in vitro in an established cell line but the present study describes the first such event in vivo in human individuals. Received: 10 May 1996     

Advantages of genome sequencing by long-read sequencer using SMRT technology in medical area

PacBio RS II is the first commercialized third-generation DNA sequencer able to sequence a single molecule DNA in real-time without amplification. PacBio RS II’s sequencing technology is novel and unique, enabling the direct observation of DNA synthesis by DNA polymerase. PacBio RS II confers four major advantages compared to other sequencing technologies: long read lengths, high consensus accuracy, a low degree of bias, and simultaneous capability of epigenetic characterization. These advantages surmount the obstacle of sequencing genomic regions such as high/low G+C, tandem repeat, and interspersed repeat regions. Moreover, PacBio RS II is ideal for whole genome sequencing, targeted sequencing, complex population analysis, RNA sequencing, and epigenetics characterization. With PacBio RS II, we have sequenced and analyzed the genomes of many species, from viruses to humans. Herein, we summarize and review some of our key genome sequencing projects, including full-length viral sequencing, complete bacterial genome and almost-complete plant genome assemblies, and long amplicon sequencing of a disease-associated gene region. We believe that PacBio RS II is not only an effective tool for use in the basic biological sciences but also in the medical/clinical setting.     

Cyclical mechanical stretch enhances degranulation and IL‐4 secretion in RBL‐2H3 mast cells

Mast cells are widely distributed in the body and affect their surrounding environment through degranulation and secretion of cytokines. Conversely, mast cells are influenced by environmental stimuli such as cyclical mechanical stretch (CMS), such as that induced by heartbeat and respiration. Peripherally distributed mast cells are surrounded by extracellular matrix, where they bind IgE on their surface by expressing the high‐affinity Fc receptor for IgE (FcεRI), and they release mediators after cross‐linking of surface‐bound IgE by allergen. To analyse how CMS affects mast cell responses, we examined the effect of applying CMS on the behaviour of IgE‐bound mast cells (RBL‐2H3 cell line) adhering to fibronectin as a substitute for extracellular matrix. We found that CMS enhanced FcεRI‐mediated secretion in the presence of antigen (2,4‐dinitrophenol–bovine serum albumin). CMS increased expression of IL‐4 mRNA and secretion of IL‐4 protein. Western blot analysis showed that CMS changes the signal transduction in mitogen‐activated protein kinases and AKT, which in turn alters the regulation of IL‐4 and increases the secretion of IL‐4. These results suggest that CMS modulates the effect of mast cells on inflammation and resultant tissue remodelling. Understanding how CMS affects mast cell responses is crucial for developing therapies to treat mast cell‐related diseases. Copyright © 2013 John Wiley & Sons, Ltd.     

Acceleration of the oxygen reaction in CuA-deficient Nitrosomonas europaea cytochrome c oxidase as revealed by the flow-flash measurement.

The oxygen reaction of Nitrosomonas europaea cytochrome c oxidase containing either 2Cu or 1Cu per two heme a molecules was investigated by the flow-flash technique at 20 degrees C. The reaction profiles of the bacterial enzyme were essentially the same as those of bovine heart cytochrome c oxidase, although the rate of the primary oxygen compound formation was much slower. The 1Cu enzyme exhibited higher rates for both primary oxygen compound formation and intramolecular electron transfer than the 2Cu enzyme. This result clearly indicates that CuA is not essential functionally for the oxidation of ferrous heme a moieties, and suggests its structural importance in maintaining the molecular integrity of N. europaea cytochrome oxidase.     

Embigin/basigin subgroup of the immunoglobulin superfamily: Different modes of expression during mouse embryogenesis and correlated expression with carbohydrate antigenic markers

Embigin and basigin are highly glycosylated transmembrane glycoproteins with two immunoglobulin domains and form a subgroup in the immunoglobulin superfamily. Previous studies have demonstrated the functional significance of these molecules. In the present study, in situ hybridization analysis of their expression was performed during mouse embryogenesis. Embigin was strongly expressed in the endoderm during early postimplantation embryogenesis, and in the somite stage in the gut and visceral endoderm. Embryonic ectoderm and its derivative tissues weakly to moderately expressed this molecule. From day 10 to 15 of gestation, no embigin signal was detected. Basigin was more broadly expressed. During the organogenesis period, basigin was expressed in various epithelial tissues, brain ventricles, the spinal cord and dorsal root ganglion. The modes of expression of these two proteins throughout the egg cylinder stage correlated with the expression of the carbohydrate markers that they carry; embigin with Dolichos biflorus agglutinin binding sites and basigin with Le^x antigen and more closely with fucosyltransferase IV, which forms the antigenic epitope. These findings imply that proteins with specific carbohydrate epitopes play roles in early postimplantation embryogenesis.