Expressional Analysis of Stem Cell Marker SALL4 in Mesencephalon during Chicken Embryogenesis

Background SALL gene family represent a group of evolutionary conserved zinc finger transcription factors which are involved in normal development. It includes four members (SALL1 to SALL4). SALL4 has significant roles in the maintenance of pluripotency and self-renewal, efficient proliferation /stabilization and cell fate decision of embryonic stem cells (ESCs). Our aim in this study was to analyze and quantify mRNA expression of SALL4 in mesencephalon, during different stages of chicken embryogenesis. Materials and methods: Ross fertilized eggs were incubated in 37°C -37.5°C in 60-65% humidified atmosphere.  After beginning of embryogenesis, Mesencephalon mesencephalon part of the brain tissue was collected each day from the eggs embryos. Total RNA extraction and cDNA synthesis was performed from resected tissues. The synthesized cDNA was used as template for quantitative analysis of SALL4 mRNA expression using real time PCR assay. Results: The Real-time PCR analysis of SALL4 mRNA expression in mesencephalon tissues indicated that the level of gene expression is significantly variable during embryogenesis. While the basal SALL4 mRNA expression was detected during the rest of embryogenesis, the maximum copy number of SALL4 mRNA was quantified on 19 th day of chicken embryogenesis. Conclusion: Having analyzed the level of SALL4 mRNA expression in different stages of chicken embryogenesis, we can extrapolate that a probable relationship may be existed between expression of SALL4 in nerve centers of mesencephalon brain and development of optic organs.   Keywords:  Expressionalanalysis, stem cell, mesencephalon

High refractive index and low-birefringence polyamides containing thiazole and naphthalene units

Highly refractive and solution processable polyamides (PAs) were synthesized by the introduction of thiazole rings, naphthalene groups, and thioether linkages. These PAs were synthesized by the polycondensation of a new diamine monomer, 5,5'-thiobis(2-amino-4-(2-naphthyl)thiazole) (DA), with various aromatic diacids. The bulky pendant naphthyl units endowed the resulting PAs with non-coplanar structures and excellent solubilities in organic solvents. The obtained PAs showed high thermal stability, with 10% weight loss temperatures exceeding 478°C under nitrogen and 431°C in air atmosphere, while their glass transition temperatures were in the range of 194-229°C. The synergic effects of the thiazole groups, naphthyl substituents, and thioether linkages provided PAs with very high refractive indices of up to 1.7701 at 632.8 nm, along with small birefringences (<0.0076) and high Abbe's numbers. The structure-property relationships of these PAs due to the presence of naphthyl substituents were also studied in detail by comparing the results with the previously reported analogous PA