Konsep Proses Pemesinan Berkelanjutan

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Novel iguana amelogenin gene cDNA structure.

<p>Analysis of novel iguana amelogenin sequence revealed the full-length amelogenin cDNA containing 7 exons including exon 1, 2, 3, 5, X, 6, and 7 (exon numbers is relative to published mammalian amelogenin exon numbers). Different from amelogenin genes of all species so far, an unique exon named exon X between exon 5 and exon 6 was detected; Similar to other species, no corresponding sequence elements were detected resembling exon 4, suggesting that amelogenin exon 4 is skipped or deleted in <i>Ctenosaura similis</i>.</p

Alignment of genomic sequences spanning exon X of <i>C. similis</i>-T2L amelogenin gene with the selected species.

<p>The black spiny-tailed iguana genomic sequence spanning the exon X was amplified by PCR and analyzed by alignment with the Carolina anole in the same region of the black spiny-tailed iguana exon X sequence. Like the majority of exons, a conserved sequence feature, the presence of AG at the 5′ splice site and GT at the 3′ splice site were observed spanning the exon X, while the same sequence region of the Carolina anole share a high sequence identity except the lack of G in AG at the 5′ splice site, which fail to generate a exon X observed in the black spiny-tailed iguana. The 5′ and 3′ splice sites in the black spiny-tailed iguana genomic sequence spanning the exon X are highlighted as red. Alignment gaps are indicated by a dash (−).</p

Novel isoforms of amelogenin gene in

<p><b><i>Ctenosaura similis</i></b><b>.</b> (A) Alignment analysis of the full-length novel iguana amelogenin cDNA sequence <i>C. similis</i>-T2S, C. <i>similis</i>-T2L, and <i>I. iguana</i>. The full-length of <i>C. similis</i>-T2S transcript is 825 bp, while <i>C. similis</i>-T2L transcript is 873 bp. In relation to <i>C. similis</i>-T2S and <i>I. iguana</i>, the <i>C. similis</i>-T2L contains additional 48 bp located between nucleotide 217 and 218. The 5′-untranslated region contains 69 bp upstream of translation start codon ATG. The 3′-untranslated region contains 183 bp. (B) Sequence analysis of deduced amino acid of <i>I. iguana</i>, <i>C. similis</i>-T2S, and <i>C. similis</i>-T2L. The <i>C. similis</i>-T2S encodes 190 amino acid residues, while <i>C. similis</i>-T2L encodes 206 amino acid residues. Additional 16 amino acid residues were revealed in the deduced <i>C. similis</i>-T2L amino acid sequence located between amino acid residue 49 and 50 in relation to <i>C. similis</i>-T2S. Similar to <i>I. iguana</i>, the T2S and T2L also have a deletion of 3 amino acid residues in exon 3. The nucleotides/amino acid sequence variations were indicated and highlighted as red color.</p

Identification of a novel amelogenin gene splicing transcript in <i>Ctenosaura similis</i>.

<p>Chromatograms showed the partial sequence of two <i>Ctenosaura similis</i> amelogenin transcripts identified by sequencing PCR-amplified products. The cDNA clones corresponding to the transcripts were designed <i>as C. similis</i>-T2L (UP) and <i>C. similis</i>-T2S (low), respectively. In relation to <i>C. similis</i>-T2S, <i>C. similis</i>-T2L contains additional nucleotides (UP).</p

Primers used for determination of the exon and intron boundaries.

<p>S refers to sense; A stands for antisense.</p

Expression of exon X protein in tooth organ. (

<p>A) The microphotograph illustrates the components of the developing iguana tooth organ, including the enamel layer (en), dental layer (de) and dental pulp (pl). (B) Expression of amelogenin protein isoform containing exon X in the <i>Ctenosaura similis</i> tooth organs by immunohistochemistry staining using antibody against iguana amelogenin exon X peptide. Immunoreaction with antibody against exon X was detected in the enamel layer (en) and dental pulp.</p

Effect of exon X sequence on the amelogenin protein structures.

<p>(A) The hydrophilicity-plot analysis using the Kyte and Doolittle algorithm. The hydrophilicity-plots of T2S and T2L and mouse (XM_136160) were generated and compared. In relation to T2S and mouse amelogenin, the region underlined with black line (middle panel) is exon X sequence, which is highly hydrophobic. (B) Exon X affects the secondary structure of T2L predicted by Psipred. Two potential helixes regions for T2S (aa 7∼16; aa 41∼43) and T2L (aa 6∼17; aa 51∼57) in relation to one potential helix region for mouse amelogenin (aa 4∼12) were revealed by Psipred prediction. A strand region (aa 32–35) was also revealed in relation to T2S and mouse amelogenin. (C) Exon X sequence effects on the tertiary structures of T2L. T2S and T2L were used as query sequence for homology detection and structure prediction by HMM-HMM comparison using HHpred. A bar graph summarizes the positions and color-coded significances of the database matches with the probability. A tabular hit lists with probabilities, E-values, scores, and match regions in query and templates.</p

Odd-Electron-Bonded Sulfur Radical Cations: X‑ray Structural Evidence of a Sulfur–Sulfur Three-Electron σ‑Bond

The one-electron oxidations of 1,8-chalcogen naphthalenes Nap­(SPh)₂ (<b>1</b>) and Nap­(SPh)­(SePh) (<b>2</b>) lead to the formation of persistent radical cations <b>1</b>^•+ and <b>2</b>^•+ in solution. EPR spectra, UV–vis absorptions, and DFT calculations show a three-electron σ-bond in both cations. The former cation remains stable in the solid state, while the latter dimerizes upon crystallization and returns to being radical cations upon dissolution. This work provides conclusive structural evidence of a sulfur–sulfur three-electron σ-bond (in <b>1</b>^•+) and a rare example of a persistent heteroatomic three-electron σ-bond (in <b>2</b>^•+)

An Aliphatic Solvent-Soluble Lithium Salt of the Perhalogenated Weakly Coordinating Anion [Al(OC(CCl₃)(CF₃)₂)₄]⁻

The facile synthesis of a new highly aliphatic solvent-soluble Li⁺ salt of the perhalogenated weakly coordinating anion [Al­(OC­(CCl₃)­(CF₃)₂)₄]⁻ and its application in stabilizing the Ph₃C⁺ cation were investigated. The lithium salt Li­[Al­(OC­(CCl₃)­(CF₃)₂)₄] (<b>4</b>) was prepared by the treatment of 4 mol equiv of HOC­(CCl₃)­(CF₃)₂ with purified LiAlH₄ in <i>n</i>-hexane from −20 °C to room temperature. Compound <b>4</b> is highly soluble in both polar and nonpolar solvents, and it bears both CCl₃ and CF₃ groups, resulting in a lower symmetry around the Al center compared to that of Li­[Al­(OC­(CF₃)₃)₄] (<b>1</b>). Treatment of <b>4</b> with Ph₃CCl afforded the ionic compound [Ph₃C]­[Al­(OC­(CCl₃)­(CF₃)₂)₄] (<b>5</b>) bearing the Ph₃C⁺ cation with concomitant elimination of LiCl, suggesting the potential application of [Al­(OC­(CCl₃)­(CF₃)₂)₄]⁻ in stabilizing reactive cationic species. Compounds <b>4</b> and <b>5</b> were fully characterized by spectroscopic and structural methods