Flying-seed-like liquid crystals 5: Liquid crystals based on octakisphenylthiophthalocyanine and their optical properties

We have synthesized three novel flying-seed-like liquid crystals based on phthalocyaninato copper(II) (abbreviated as PcCu) substituted by bulky groups {(o-C-1)PhS (i), (m-C-1)PhS (j), [m, p(C-1)(2)]PhS (k)} instead of using long alkyl chains, in order to investigate their mesomorphism. Their phase transition behavior and the mesophase structures have been established by using a polarizing optical microscope, a differential scanning calorimeter, and a temperature-dependent small angle X-ray diffractometer. As the results, [(o-C-1)PhS](8)PcCu (8i), [(m-C-1)PhS](8)PcCu (8j) and {[m,p-(C-1)(2)]PhS}(8)PcCu (8k) show a Col tet. o mesophase at 314.9 similar to 362.9 degrees C, a Col(ro) (P2m) mesophase at 287.4 similar to 334.2 degrees C and a Col(ro) (P2m) mesophase at 331.8 similar to 386.8 degrees C, respectively. Very interestingly, each of the derivatives thus exhibits a columnar mesophase at very high temperatures. The mesomorphism is apparently originated from the novel bulky groups (i similar to k). It is also noteworthy that the Q-bands of the present PhScontaining Pc derivatives 8i similar to 8k in THF significantly red-shift by about 35 nm in comparison with those of the corresponding PhO-containing derivatives in THF.ArticleJOURNAL OF PORPHYRINS AND PHTHALOCYANINES. 19(5):639-650 (2015)journal articl

Image-based quantitative determination of DNA damage signal reveals a threshold for G2 checkpoint activation in response to ionizing radiation

Background: Proteins involved in the DNA damage response accumulate as microscopically-visible nuclear foci on the chromatin flanking DNA double-strand breaks (DSBs). As growth of ionizing radiation (IR)-induced foci amplifies the ATM-dependent DNA damage signal, the formation of discrete foci plays a crucial role in cell cycle checkpoint activation, especially in cells exposed to lower doses of IR. However, there is no quantitative parameter for the foci which considers both the number and their size. Therefore, we have developed a novel parameter for DNA damage signal based on the image analysis of the foci and quantified the amount of the signal sufficient for G2 arrest.Results: The parameter that we have developed here was designated as SOID. SOID is an abbreviation of Sum Of Integrated Density, which represents the sum of fluorescence of each focus within one nucleus. The SOID was calculated for individual nucleus as the sum of (area (total pixel numbers) of each focus) x (mean fluorescence intensity per pixel of each focus). Therefore, the SOID accounts for the number, size, and fluorescence density of IR-induced foci, and the parameter reflects the flux of DNA damage signal much more accurately than foci number. Using very low doses of X-rays, we performed a "two-way" comparison of SOID of Ser139-phosphorylated histone H2AX foci between G2-arrested cells and mitosis-progressing cells, and between mitosis-progressing cells in the presence or absence of ATM or Chk1/2 inhibitor, both of which abrogate IR-induced G2/M checkpoint. The analysis revealed that there was a threshold of DNA damage signal for G2 arrest, which was around 4000~5000 SOID. G2 cells with < 4000 SOID were neglected by G2/M checkpoint, and thus, the cells could progress to mitosis. Chromosome analysis revealed that the checkpoint-neglected and mitosis-progressing cells had approximately two chromatid breaks on average, indicating that 4000~5000 SOID was equivalent to a few DNA double strand breaks.Conclusions: We developed a novel parameter for quantitative analysis of DNA damage signal, and we determined the threshold of DNA damage signal for IR-induced G2 arrest, which was represented by 4000~5000 SOID. The present study emphasizes that not only the foci number but also the size of the foci must be taken into consideration for the proper quantification of DNA damage signal

Discotic liquid crystals of transition metal complexes 48: Synthesis of novel phthalocyanine-fullerene dyads and effect of a methoxy group on their clearing points

In our previous work, we could successfully synthesize the 1:1 phthalocyanine-fullerene (Pc-C-60) dyads, (OFbaC(60))PcCu(OCH3) 2, in very high yields (81 similar to 96%) by using Prato reaction. In this study, we have prepared novel Pc-C-60 dyads, (OFbaC(60)) PcM (M = Co (a), Ni (b), Cu (c), metal free (d)) 3a-3d without the methoxy group. The target Pc-C-60 dyads 3a-3d could be successfully synthesized in good yields also by Prato reaction. It is surprising for us that removal of a very small methoxy group from the big (OFbaC(60))PcCu(OCH3) molecule (2) significantly lowers the cp of (OFbaC(60))PcCu (3c) by about 70 degrees C in comparison with that of 2 having the methoxy group. Very interestingly, each of the novel dyads 3a-3d synthesized here shows perfect homeotropic alignment in the tetragonal columnar phase (Col(tet)). Moreover, it is noteworthy that 3c and 3d show only one Col(tet.o) mesophase having ordered stacking distance with perfect homeotropic alignment. Such simple phase transition can contribute to maintain stable performance in wide temperature range, when they will be applied to organic thin film solar cells.ArticleJOURNAL OF PORPHYRINS AND PHTHALOCYANINES. 17(4):264-282 (2013)journal articl

Evaluation of Fiber Crops as Adsorption Materials for Cesium and Strontium Ions

After the accident of atomic power plants in Fukushima, Japan, the removal of radioactive materials released to environment is most important task and rapid response to the severe problem is required. It is well known that various biomass have adsorption ability for toxic metal ions from aqueous media. We have evaluated the adsorption ability of many fiber crops for cesium and strontium ions. As the results, several fiber crops have considerable ability for the adsorption of such metal ions and are useful for a water and soil purification system in large scale

Discotic liquid crystals of transition metal complexes 50(dagger): spiranthes-like supramolecular structure of phthalocyanine-fullerene dyads

We have synthesized novel liquid crystalline Pc-C-60 dyads (CnS)(6)PcCu-C-60 (n = 14, 16, 18: 1a-1c) by using our developed synthetic method in order to investigate the mesomorphism and alignment behavior. Each of the (CnS)(6)PcCu-C-60 dyads shows perfect homeotropic alignment in the Col(ho) mesophase between two glass plates for n = 14, 16, 18 and also on a glass plate for n = 14, although none of the parent Pc compounds (CnS)(8)PcCu and the Pc precursors (CnS)(6)PcCu-OH and (CnS)(6)PcCu-OFBA shows homeotropic alignment. It may be attributed to the strong affinity between fullerene and glass surface. Although the reason is not so clear at the present time, this is very useful guideline for the molecular design to prepare homeotropic alignment-showing discotic liquid crystals. Very interestingly, the spherical C-60 parts form a helical structure around the column formed by the disk-like Pc parts. This supramolecular structure very resembles spiranthes. The spiranthes-like supramolecular structure is compatible with one-dimensional nano-array expecting the high conversion efficiency of solar cells.ArticleJOURNAL OF PORPHYRINS AND PHTHALOCYANINES. 18(5):366-379 (2014)journal articl

Characteristics of urine spraying and scraping the ground with hind paws as scent-marking of captive cheetahs (Acinonyx jubatus)

Olfactory communication is common in felids. We observed two scent-markings, urine spraying and scraping the ground with hind paws during excretion, of 25 captive cheetahs. We analyzed the association of sniffing with the timing of urine spraying and scraping, and differences in these behaviors based on sex, age, and captive environment to understand the olfactory communication among cheetahs. Both scent-markings were strongly associated with sniffing, especially scraping, and the presence or absence of scent was thought to be a trigger. Both behaviors were observed only in adults; scraping was observed only in males. To our knowledge, this study was first to confirm the discharge of secretions from the anal glands during scraping. The frequencies of both behaviors were significantly higher in males kept in shared enclosures containing other individuals than in males kept in monopolized enclosures, while there was no difference in the frequencies among females. Female cheetahs are solitary and have non-exclusive home range, whereas male cheetahs are either solitary or live in coalition groups and there are territorial and non-territorial males. Our results could be attributed to the differences in sociality between the sexes and effect of the living environment

Sox21 Regulates Anapc10 Expression and Determines the Fate of Ectodermal Organ

The transcription factor Sox21 is expressed in the epithelium of developing teeth. The present study aimed to determine the role of Sox21 in tooth development. We found that disruption of Sox21 caused severe enamel hypoplasia, regional osteoporosis, and ectopic hair formation in the gingiva in Sox21 knockout incisors. Differentiation markers were lost in ameloblasts, which formed hair follicles expressing hair keratins. Molecular analysis and chromatin immunoprecipitation sequencing indicated that Sox21 regulated Anapc10, which recognizes substrates for ubiquitination-mediated degradation, and determined dental-epithelial versus hair follicle cell fate. Disruption of either Sox21 or Anapc10 induced Smad3 expression, accelerated TGF-beta 1-induced promotion of epithelial-to-mesenchymal transition (EMT), and resulted in E-cadherin degradation via Skp2. We conclude that Sox21 disruption in the dental epithelium leads to the formation of a unique microenvironment promoting hair formation and that Sox21 controls dental epithelial differentiation and enamel formation by inhibiting EMT via Anapc10.Peer reviewe

異なるドロップ高からの着地における筋活動の調節

Pre-activation before ground impact can play an important roles during drop jumps（DJ）. The purpose of this study was to examine the regulation of triceps surae muscle activation during DJs. Seven healthy subjects dropped from 3 different heights, and were asked to not rebound （landing only: LAND） or rebound with maximal effort （RJmax）. Joint angular data, ground reaction force and electromyography of the lower leg muscles were simultaneously recorded during each DJ. With higher drop heights, agonist muscle activities （medial gastrocnemius and soleus muscles） during the pre-activation phase were dramatically increased, while those did not show any differences during braking phase. The increased agonist muscle activation before touchdown（pre-activation） was significantly decreased during the following braking phase for regulation of low stiffness in the LAND. The agonist muscle activities during braking phase were increased with stiffness index of muscle-tendon unit from LAND to RJmax during constant drop height. However, the pre-activation of the agonist muscle was not increased while that of the corresponding antagonist tibialis anterior muscle was significantly increased from LAND to RJmax. During the following braking phase, the antagonist muscle activities were not increased. These results suggest that the effects of agonist muscle pre-activation are mainly for the impact of touchdown, and not for the regulation of landing or rebound. Consequently, the antagonist pre-activation and the agonist muscles activation of braking phase may play important roles to control motion after landing, and regulate stiffness