Primary structure of gum arabic and its dynamics at oil/water interface.

Gum arabic (GA), an arabinogalactan-based gum, is a well-known powerful emulsifier. However, the poor stability of emulsion has often been pointed out. In order to clarify the origin, the structure-property relationship of GA, especially the interfacial property at oil/water interface, needs to be investigated. Here, we tried to correlate the primary structure with interfacial property at oil/water interface. A series of structural analyses by SEC-MALLS, SAXS, etc. showed that the primary structure of GA was a disk-like star shaped nanoparticle. The dynamic interfacial tension measurement showed that GA molecules adsorb onto oil surface in 2 steps: Firstly, the micron-aggregates of GA approach onto the oil surface, and then the aggregates are dissociated into nano-particles so that they cover the oil surface. Therefore, the emulsification and emulsion stability are controlled not by the property of the primary structure of GA but by the higher-order molecular network structure made of GA molecules.

Free-Radical Polymerization of Acrylic Acid under Extreme Reaction Conditions Mimicking Deep-Sea Hydrothermal Vents.

Free-radical polymerization with a thermochemical initiator, which usually takes hours to complete, was dramatically accelerated under reaction conditions mimicking the deep-sea hydrothermal vents, where reaction mixtures were only briefly exposed to ultrahigh temperatures under pressure. In tests using acrylic acid and potassium persulfate, poly(acrylic acid) (M n = 2.1 × 104, D = 2.73) was obtained in 5.2 s with the monomer conversion of 60.3% in water at 200 °C and 25 MPa without using any catalysts. The process that we call heat-shock-induced polymerization may pave the way for an entirely new strategy in reaction engineering for developing extremely fast, green, and scalable processes for polymer synthesis.

Preparations of polystyrene/aluminum hydroxide and polystyrene/alumina composite particles in an ionic liquid.

Polystyrene (PS)/aluminum hydroxide (Al(OH)(3)) composite particles were successfully prepared by the sol-gel process of aluminum isopropoxide (Al(OPr(i))(3)) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF(4)]) using ammonium hydroxide (NH(4)OH) as a catalyst in the presence of PS seed. Transmission electron microscopy observation of ultrathin cross-sections of the composite particles revealed that the composite particles had a core-shell morphology consisting of a PS core and a Al(OH)(3) shell having high crystallinity. The amount of secondary nucleated Al(OH)(3) could be reduced by dropwise addition of NH(4)OH. Moreover, PS/η-Al(2)O(3) composite particles were successfully prepared by heat treatment of PS/Al(OH)(3) at 300 °C in N(2) atmosphere, which is below the decomposition temperature of PS.

Preparation of poly(acrylic acid) particles by dispersion polymerization in an ionic liquid.

Poly(acrylic acid) (PAA) particles were successfully prepared by dispersion polymerization of acrylic acid in ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoro-methanesulfonyl)amide ([DEME][TFSA]) at 70 degrees C with low hydrolysis grade (35.4%) poly(vinyl alcohol) as stabilizer. Interestingly, the PAA particles were easily extracted as particle state with water. Thus, the PAA particles had a cross-linked structure during the polymerization without cross-linker. Moreover, it was also noted that the cross-linking density of the PAA particles could be controlled by thermal treatment at various temperatures in [DEME][TFSA] utilizing the advantages of nonvolatility and high thermal stability of the ionic liquid.

Overexpression of SOX15 inhibits proliferation of NT2/D1 cells derived from a testicular embryonal cell carcinoma.

SOX (Sry-related HMG box) family proteins, which have an evolutionarily conserved DNA binding domain, have crucial roles in cell differentiation. However, their target genes remain enigmatic. Some members of the SOX family may have roles in regulation of cell proliferation. We established stable NT2/D1 cell lines overexpressing SOX15 (SOX15-NT2/D1), and a modified 3-(4,5-dime-thylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that the SOX15-NT2/D1 cells exhibited significantly slower growth than the controls. Flow cytometry analysis revealed that an increased fraction of the SOX15-NT2/D1 cells were in G1-G0. In addition, a microarray analysis identified 26 genes that were up-regulated in the SOX15-NT2/D1 cells, but none that were down-regulated genes. Among the up-regulated genes, IGFBP5, S100A4, ID2, FABP5, MTSS1, PDCD4 have been shown to be related to cell proliferation and/or the cell cycle.

Expression analysis of a mouse orthologue of HSFY, a candidate for the azoospermic factor on the human Y chromosome.

Heat shock transcription factor on Y (HSFY) is located in one of three candidate regions for azoospermic factor (AZF), AZFb on the Y chromosome. We and others have already revealed that some azoospermic males are missing the regions of the Y chromosome including HSFY. Previously, we showed that murine HSFY-like sequence [mHSFYL (Riken cDNA 4933413G11Rik)], which is the mouse orthologue of HSFY, is exclusively expressed in testis. The sequences encoding the presumed DNA-binding domain in HSFY and mHSFYL were found in other mammals such as dogs, cows and chickens. To elucidate mHSFYL expression in the testes in detail, we carried out in situ hybridization. mHSFYL was predominantly expressed in round spermatids. Furthermore, we clarified the intracellular distribution of mHSFYL in COS1 cells with HA- or GFP-tagged proteins. Both HA-mHSFYL and GFP-mHSFYL were located in the nucleus. Our results suggest that HSFY/mHSFYL may have evolutionarily conserved functions for spermatogenesis.

Molecular analysis of TBL1Y, a Y-linked homologue of TBL1X related with X-linked late-onset sensorineural deafness.

Recent progress in sequencing the human Y chromosome has unveiled a series of X-Y homologous genes. In the present study, we focused on Transducin beta-like 1Y (TBL1Y), which is a Y-linked homologue of TBL1X that is related with X-linked late-onset sensorineural deafness. Recently, it has been shown that TBLR1, another homologue whose gene resides on chromosome 3, and TBL1X act as a corepressor/coactivator exchanger for several nuclear receptors and transcription factors. However, the expression pattern and function of TBL1Y remain unknown. The RT-PCR analysis of the TBL1 family revealed that TBL1Y was expressed in all 13 tissues examined but not in leukocytes. Among the cell lines tested, however, it was only expressed in NT2/D1 cells and in lymphoblasts transformed with Epstein Barr (EB) virus. To compare the functions of the TBL1 family, we generated a series of expression plasmids for GAL4DBD-fused proteins of the TBL1 family. We carried out dual luciferase assays using these plasmids in combination with a plasmid having a luciferase reporter gene harboring 5xGAL4 binding sites. Unlike the other constructs, GAL4DBD-fused TBL1Y did not repress the promoter activity. Moreover, we found three novel polymorphisms in the TBL1Y gene, IVS7+9G>A, G268C, and IVS7+1G>C, which is presumed to cause splicing error. These polymorphisms are found in males within Y-haplogroup O3 (XO3e), which is defined as the Y-haplogroup O3 excluding O3e, a branch of O3. The results show that TBL1Y differs from other members of the TBL1 family in expression and function, suggesting other roles in maleness.

Molecular characterization of heat shock-like factor encoded on the human Y chromosome, and implications for male infertility.

Azoospermia and oligospermia are major causes of male infertility. Some genes located on the Y chromosome are suggested as candidates. Recently, HSFY, which is similar to the HSF (heat shock transcription factor) family, has been mapped on the human Y chromosome as multicopies. However, newly available sequence data deposited at NCBI shows that only the HSFY gene located on Yq has a long open reading frame containing a HSF-type DNA-binding domain. HSFY is similar to LW-1 on the human X chromosome and a murine HSFY-like sequence (mHSFYL), 4933413G11Rik, on the mouse chromosome 1. LW-1 and mHSFYL have 53% and 70% homology to HSFY for amino acid sequences of their presumed DNA-binding domains, respectively. Comparison of the presumed DNA-binding domains unveiled that the three HSF-like factors, HSFY, LW-1, and mHSFYL, belong to a different class than conventional HSFs. When we screened for deletions on the Yq of males suffering from infertility, we found that HSFY was involved in interstitial deletions on the Y chromosomes for two azoospermic males who had DBY, USP9Y, and DAZ but did not have RBMY located on the AZFb. Expression analysis of HSFY, LW-1, and mHSFYL unveiled that they are expressed predominantly in testis. Furthermore, immunhistochemistry of HSFY in testis showed that its expression is restricted to both Sertoli cells and spermatogenic cells and that it exhibits a stage-dependent translocation from the cytoplasm to the nucleus in spermatogenetic cells during spermatogenesis. These results may suggest that deletion of HSFY is involved in azoospermia or oligospermia.

Roles of estrogen receptor alpha (ER alpha) in the regulation of the human Müllerian inhibitory substance (MIS) promoter.

Sex differentiation consists of multi-step pathway that involves expression of many different genes. Müllerian duct inhibitory substance (MIS) has a key role for regression of the Müllerian duct during male sex differentiation. Recently, endocrine disruptors (EDs), which often have estrogen-like activities, have caused concern over worldwide. It has been reported that estrogen regulates the MIS expression. Therefore, we tested whether ER alpha and ER beta influence the MIS promoter activity in the NT2/D1 cell line which expresses many sex differentiation-related genes such as SRY, SOX9, and DAX-1. RT-PCR analysis revealed that the NT2/D1 cells express both ER alpha and ER beta in addition to MIS. Under the low concentration of 17beta-estradiol (E2), the over-expression of exogenous ER alpha increased the MIS promoter activity 3.3-fold compared with the control. However, as E2 concentration was increased, the MIS promoter activity was decreased. For ER beta, we could not observe alterations of the MIS promoter activity. Furthermore, the over-expression of the exogenous SF-1 inhibited the activation of the MIS promoter with ER alpha. Although it remains unclear whether the effects of ER alpha on the MIS promoter are mediated through the genomic or the no-genomic actions, the present results suggest that ER alpha up-regulates the MIS promoter activity in the NT2/D1 cells under low concentrations of E2, and that the two ERs may work in different manners for the MIS promoter activation. The present findings may be useful to understand the molecular mechanisms by which EDs or estrogens affect the MIS expression.