Multi-wavelength Stellar Polarimetry of the Filamentary Cloud IC5146: I. Dust Properties

We present optical and near-infrared stellar polarization observations toward the dark filamentary clouds associated with IC5146. The data allow us to investigate the dust properties (this paper) and the magnetic field structure (Paper II). A total of 2022 background stars were detected in $R_{c}$-, $i'$-, $H$-, and/or $K$-bands to $A_V \lesssim 25$ mag. The ratio of the polarization percentage at different wavelengths provides an estimate of $\lambda_{max}$, the wavelength of peak polarization, which is an indicator of the small-size cutoff of the grain size distribution. The grain size distribution seems to significantly change at $A_V \sim$ 3 mag, where both the average and dispersion of $P_{R_c}/P_{H}$ decrease. In addition, we found $\lambda_{max}$ $\sim$ 0.6-0.9 $\mu$m for $A_V>2.5$ mag, which is larger than the $\sim$ 0.55 $\mu$m in the general ISM, suggesting that grain growth has already started in low $A_V$ regions. Our data also reveal that polarization efficiency (PE $\equiv P_{\lambda}/A_V$) decreases with $A_V$ as a power-law in $R_c$-, $i'$-, and $K$-bands with indices of -0.71$\pm$0.10, -1.23$\pm$0.10 and -0.53$\pm$0.09. However, $H$-band data show a power index change; the PE varies with $A_V$ steeply (index of -0.95$\pm$0.30) when $A_V < 2.88\pm0.67$ mag but softly (index of -0.25$\pm$0.06) for greater $A_V$ values. The soft decay of PE in high $A_V$ regions is consistent with the Radiative Aligned Torque model, suggesting that our data trace the magnetic field to $A_V \sim 20$ mag. Furthermore, the breakpoint found in $H$-band is similar to the $A_V$ where we found the $P_{R_c}/P_{H}$ dispersion significantly decreased. Therefore, the flat PE-$A_V$ in high $A_V$ regions implies that the power index changes result from additional grain growth.Comment: 31 pages, 17 figures, and 3 tables; accepted for publication in Ap

Pedigree of family 2048 with Stargardt.

<p>Solid symbols indicated affected individuals. Open symbols indicated unaffected individuals and arrow indicates the proband.</p

Topological organization of ABCA4 and conservation analysis.

<p>(A) Protein alignment showed conservation of residues ABCA4 Y808X and G607R across nine species. These two mutations occured at an evolutionarily conserved amino acid. The ABCA4 mutation G607R occured in the NBD1 while Y808X occured in the disc lumen region between TMD1. (B) Topological organization of ABCA4 in the disc membrane was shown. The domain organization included exocytoplamic domain (ECD), nucleotide binding domain (NBD) and transmembrane domain (TMD).</p

Conditions used for genotyping assays.

<p>Conditions used for genotyping assays.</p

Representative photographs of patients of family 2048.

<p>(A) Fundus photographs showing pigment mottling and yellow-white flecks in both maculae. (B) Fluorescein angiography (FA) images showing the hyperfluorescent flecks extended to the midperipheral retina and fluorescence blocking by the pigment mottling in the mcular. (C) mfERG records showing severe depressed central waveform and significant paracentral/pereferral loss of retinal response. (D) Macular OCTs showing hyper-reflective deposits within the RPE layer and the level of the outer segments of the photoreceptors, thinning of the retinal outer layers and enhanced choroidal reflectivity associated with overlying atrophic retina.</p

Iodine and GPXs involved in Thyroid Hormones Biosynthesis.

<p>The serum sodium iodide is transported into the thyrocyte and then iodine is incorporated into the thyroglobulin molecule (Tg) in a reaction catalyzed by the hemoprotein thyroid peroxidase (TPO). In this reaction, H₂O₂ generated by the NADPH-dependent thyroxidase (ThOx) is required as substrate by TPO for the iodination and coupling of tyrosyl residues in Tg. Then, thyroid hormones triiodothyronine (T3) and tetraiodothyronine (T4) are released into the bloodstream. H₂O₂ used in this reaction decreases the amount of H₂O₂ that would otherwise be available for damaging oxidation reactions. Selenium-dependent glutathione peroxidase 1 (<i>GPX 1</i>) and other GPX s remove H₂O₂ from the tissues, also decreasing oxidative damage. (Modified from: J. Köhrle <i>et al</i>. Selenium, the thyroid, and the endocrine system. Endocrine Reviews, December 2005, 26(7):944–984; Lyn Patrick, ND. Iodine: deficiency and therapeutic considerations. Alternative Medicine Review, 2008, 13(2):116–127).</p

Phenotype and genotype of the family members.

<p>N/A, Not available; M, Male; F, Female.</p

Genotype and allele frequencies of polymorphisms across selenoprotein genes by serum selenium concentration in Tibetan population.

<p>Genotype and allele frequencies of polymorphisms across selenoprotein genes by serum selenium concentration in Tibetan population.</p

Mutation identification of <i>ABCA4</i> gene.

<p>Electropherogram analysis of <i>ABCA4</i> in family 2048 showing the compound heterozygous mutations (c.C2424G and c.G1819A) co-segregated with the phenotype. II1 and II2 patients harbored compound heterozygous c.C2424G and c.G1819A mutations of the <i>ABCA4</i> gene. c.C2424G mutation was carried by the mother I2 while c.G1819A mutation was carried by the father I1.</p

Characteristics of the KBD cases and controls.

<p>Characteristics of the KBD cases and controls.</p