新しいBis-GMA類似体を基調としたコンポジットレジンペースト性質と特徴

The relationship between filler type, filler content, and matrix resin composition and viscosity, and the flow characteristics of composite formulations were investigated. The structures of three newly synthesized monomers, i.e., 3F Bis-GMA, 6F Bis-GMA (Bis-GMA analogues) and IP AGDM (based on phthalic acid) were analyzed to determine their viscosity and polymerization shrinkage. Viscosities were determined with a cone and plate viscometer and shrinkages were determined gravimetrically. All three experimental monomers required less dilution than Bis-GMA, and they exhibited remarkable reductions in polymerization shrinkage relative to Bis-GMA. Bis-GMA and 4 experimental Bis-GMA analogues were also evaluated. For each monomer-filler combination, increasing filler contents resulted in monotonic plasticities. The maximum filler contents appeared to be an attribute of the particular filler rather than a matrix resin characteristic. Plasticity differences existed, unexpectedly, even at constant filler contents and matrix viscosities. Evidence was found that the plasticity varied with the base monomer composition and the amount of TEGDMA present

DEAD-Box Protein Ddx46 Is Required for the Development of the Digestive Organs and Brain in Zebrafish

Spatially and temporally controlled gene expression, including transcription, several mRNA processing steps, and the export of mature mRNA to the cytoplasm, is essential for developmental processes. It is well known that RNA helicases of the DExD/H-box protein family are involved in these gene expression processes, including transcription, pre-mRNA splicing, and rRNA biogenesis. Although one DExD/H-box protein, Prp5, a homologue of vertebrate Ddx46, has been shown to play important roles in pre-mRNA splicing in yeast, the in vivo function of Ddx46 remains to be fully elucidated in metazoans. In this study, we isolated zebrafish morendo (mor), a mutant that shows developmental defects in the digestive organs and brain, and found that it encodes Ddx46. The Ddx46 transcript is maternally supplied, and as development proceeds in zebrafish larvae, its ubiquitous expression gradually becomes restricted to those organs. The results of whole-mount in situ hybridization showed that the expression of various molecular markers in these organs is considerably reduced in the Ddx46 mutant. Furthermore, splicing status analysis with RT-PCR revealed unspliced forms of mRNAs in the digestive organ and brain tissues of the Ddx46 mutant, suggesting that Ddx46 may be required for pre-mRNA splicing during zebrafish development. Therefore, our results suggest a model in which zebrafish Ddx46 is required for the development of the digestive organs and brain, possibly through the control of pre-mRNA splicing

Phenotype of the <i>mor^ha4</i> mutant.

<p>(A–F) Lateral (A–D) and dorsal (E, F) views of live WT and <i>mor^ha4</i> larvae at 5.5 dpf. The swim bladder failed to inflate (arrows in A, B), the intestine lacked folds (arrowheads in C, D), and the retinae were reduced in size (brackets in E, F) in the <i>mor^ha4</i> mutant. Conversely, somite formation in the <i>mor^ha4</i> mutant appeared normal (arrowheads in A, B). (G–L) Sagittal sections of 5.5-dpf larvae stained with hematoxylin and eosin. The intestine lacked folds and was thin walled (arrowheads in G, H), and the exocrine pancreas (blue dotted lines in I, J) and liver (blue dotted lines in K, L) were small in the <i>mor^ha4</i> mutant. In contrast, the endocrine pancreas (blue dotted lines in I, J) in WT larvae was indistinguishable from that in <i>mor^ha4</i> larvae. Scale bars, 50 µm. (M–P) Dorsal views, anterior to the top (M, N). Lateral views, anterior to the left (O, P). Apoptotic cells were detected using the TUNEL method. An increase in apoptotic cells was evident in the brain, retinae, and posterior intestine of the <i>mor^ha4</i> larvae (white arrowheads in O, P) compared to WT larvae, but not in the <i>mor^ha4</i> somite (white arrows in O, P). en, endocrine pancreas; ex, exocrine pancreas.</p

<i>Ddx46</i> deficiency affects pre-mRNA splicing in the digestive organs and brain.

<p>(A–H) Scheme of the <i>dla</i>, <i>her6</i>, <i>ptf1a</i>, and <i>fabp10a</i> pre-mRNA regions analyzed for splicing (boxes, exons; lines, introns; arrows, primers) (A, C, E, G). The splicing status of <i>dla</i>, <i>her6</i>, <i>ptf1a</i>, and <i>fabp10a</i> pre-mRNA was monitored using RT-PCR with the primers indicated in scheme A, C, E, and G, respectively. Unspliced <i>dla</i>, <i>her6</i>, <i>ptf1a</i>, and <i>fabp10a</i> mRNAs were retained in the <i>Ddx46^{hi2137/hi2137}</i> mutant (mut) larvae compared to the control (con) larvae (arrowheads in B, D, F, H). Unspliced and spliced PCR products were verified by sequencing. +RT refers to the validation reaction itself, and −RT represents the respective control reaction without reverse transcriptase. <i>actb1</i> is a loading control by using primers designed in the exon 6. M, DNA size markers (sizes in bp); the asterisks point to nonspecific PCR products. Control larvae were sibling WT or <i>Ddx46^hi2137/+</i> larvae and had normal phenotypes.</p

<i>Ddx46</i> expression in the developing zebrafish.

<p>(A–K) <i>Ddx46</i> expression was examined using whole-mount <i>in situ</i> hybridization in WT embryos or larvae at the 128-cell (A), 6-somite (B), 1-dpf (C), 2-dpf (D–G), and 4-dpf (H–K) stages. Lateral view, animal pole to the top (A). Lateral views, anterior to the left (B, C, D, F, H, J). Dorsal views, anterior to the top (E, G, I, K). The <i>Ddx46</i> transcript was maternally supplied and continued to be expressed ubiquitously during the somitogenesis stages (A, B). By 1 dpf, <i>Ddx46</i> expression became restricted to the head region (C). At 2 dpf, strong <i>Ddx46</i> expression was prominent in the head, pectoral fin bud, and digestive organs (D–G). At 4 dpf, <i>Ddx46</i> expression was further restricted to the retina, telencephalon, midbrain, midbrain-hindbrain boundary, branchial arch, esophagus, liver, pancreas, and intestinal bulb (H–K). No <i>Ddx46</i> transcript was detected in the somite (arrowhead in H). (L, M) <i>Ddx46</i> expression was examined using whole-mount <i>in situ</i> hybridization in WT larvae at 3 dpf. Dorsal views, anterior to the top (L). A transverse section was cut at the level indicated by the black dotted line in L. The section revealed <i>Ddx46</i> expression in the intestine and exocrine pancreas, but not in the endocrine pancreas (M). b, branchial arches; e, esophagus; en, endocrine pancreas; ex, exocrine pancreas; i, intestine; ib, intestinal bulb; L, liver; m, midbrain; mhb, midbrain-hindbrain boundary; p, pancreas; pf, pectoral fin bud; r, retina; t, telencephalon.</p