Condensation reactions of phenolic resins V: cure-acceleration effects of propylene carbonate     

Naruyuki?Kamo  Hiroyuki?Okamura  Mitsuo?Higuchi  Mitsuhiro?MoritaEmail author 《Journal of Wood Science》2004,50(3):236-241

Propylene carbonate (PC) is known as one of the cure accelerators for alkaline phenol–formaldehyde resins. To elucidate the cure-acceleration mechanisms, the effects of PC on the condensation reactions of monomeric hydroxymethylphenols (HMPs) were investigated and compared with those of PC hydrolysate, sodium bicarbonate (NaHCO₃) and ethyl formate. Immediately after the reaction started, PC, decomposing itself simultaneously, accelerated the formation of the ortho-para methylene-bonded dimer of 2,4,6-trihydroxymethylphenol. This effect of PC was very similar to that of ethyl formate. To the contrary, PC hydrolysate accelerated the formation of the para-para methylene-bonded dimer throughout the course of the reaction. This effect of PC hydrolysate was identical to that of NaHCO₃. These results indicate that PC increases the reactivity of the ortho-hydroxymethyl group, presumably through transesterification. On the other hand, NaHCO₃ is formed by the hydrolysis of PC or decomposition of the transesterified HMPs and it increases the reactivity of the para-hydroxymethyl group.  相似文献   

Effect of bamboo vinegar on regulation of germination and radicle growth of seed plants   总被引：10，自引：0，他引：10  

Jun Mu  Tohru Uehara  Takeshi Furuno 《Journal of Wood Science》2003,49(3):262-270

 Two kinds of bamboo vinegar from madake bamboo (Phyllostachys bambusoides) and moso bamboo (Phyllostachys pubescens) were prepared to analyze their components by gas chromatography (GC). The original vinegar, distilled vinegar, ether-extracted vinegar, and three fractions including acidic, neutral, and phenolic fractions separated from ether-extracted vinegar were diluted with distilled water 10² to 10⁷ times. These diluted vinegar solutions were used to investigate the effect of bamboo vinegar on the germination and radicle growth of seed plants. High concentrations of all kinds of treated bamboo vinegars (e.g., 10² of original vinegar and 10³ of ether-extracted vinegar) showed strong inhibition against germination of the seeds. However, an appropriate dilution of bamboo vinegar showed an obvious promotional effect on germination and radicle growth for the four kinds of tested seeds (lettuce, watercress, honewort, chrysanthemum). Received: December, 12, 2001 / Accepted: July 29, 2002 RID="*" ID="*" Part of this paper was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001  相似文献   

Effect of quercetin derivatives on melanogenesis stimulation of melanoma cells     

Tohru Mitsunaga  Kosei Yamauchi 《Journal of Wood Science》2015,61(4):351-363

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Reinforcement of wood flour board containing ligno-cellulose nanofiber made from recycled wood     

Yoichi Kojima  Atsushi Ishino  Hikaru Kobori  Shigehiko Suzuki  Hirokazu Ito  Rie Makise  Itsuro Higuchi  Masaki Okamoto 《Journal of Wood Science》2015,61(5):492-499

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The sex determining gene of medaka: a Y-specific DM domain gene (DMY) is required for male development     

Masaru Matsuda  Yoshitaka Nagahama  Tohru Kobayashi  Chika Matsuda  Satoshi Hamaguchi  Mitsuru Sakaizumi 《Fish physiology and biochemistry》2003,28(1-4):135-139

Although the sex-determining gene Sry has been identified in mammals, no comparable genes have been found in non-mammalian vertebrates. To clone positionally the sex-determining region of the medaka, Oryzias latipes, we generated a Y congenic strain to highlight the genetic differences between the X and Y chromosomes from inbred strains of medaka. We used recombinant breakpoint analysis and deletion analysis of the Y chromosome of a congenic XY female to restrict the sex-determining region to 250-kb stretch of the Y chromosome. Shotgun sequencing of this region predicted 27 genes. Three of these genes were expressed during sexual differentiation. However, only one gene was Y specific. The full-length cDNA sequence of this gene encodes a putative protein of 267 amino acids, including the highly conserved DM domain. We thus named it DMY. To establish a role for DMY during sexual differentiation, we screened wild medaka populations for naturally occurring DMY mutants. Two XY females with distinct mutations in DMY were found in separate populations. The first heritable mutant – a single insertion in exon 3 and the subsequent truncation of DMY – resulted in all XY female offspring. Similarly, the second XY mutant female showed reduced DMY expression with a high proportion of XY female offspring. Furthermore, during normal development, DMY is expressed only in somatic cells of XY gonads. These findings strongly suggest that the sex-specific DMY is required for normal testicular development and is a prime candidate for the medaka sex-determining gene.  相似文献   

The complementary DNA sequence and polymorphisms of bovine procathepsin-D (CTSD)     

M. Higuchi  N. Miyashita  Y. Nagamine  A. Watanabe  T. Awata 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2003,120(5):322-330

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The effects of human disturbance on a stingless bee community in a tropical rainforest     

Hiromitsu Samejima  Marfaizal Marzuki  Teruyoshi Nagamitsu  Tohru Nakasizuka 《Biological conservation》2004,120(4):577-587

Human disturbance of tropical rainforests may change pollinator communities indirectly as a result of changes in resource availability. We studied the mechanisms by which human disturbance affects a community of major pollinators, stingless bees, in Sarawak, Malaysia. We surveyed forest structure and flowering activity, and conducted a nest census and a bait-trap survey of stingless bees, both in primary forests and in forests disturbed by logging and shifting cultivation. The densities of late successional trees and large trees (diameter at breast height >50 cm) were higher in the primary forests than in the disturbed forests. The density of flowering trees was lower one year after logging, but recovered in old disturbed forests because of the active flowering of pioneer trees that became established after the disturbance. Stingless bees nest only in large trees, and nest density was positively correlated with the density of large trees. However, we found no relationship between the numbers of foragers and floristic parameters. Some species preferred nesting in dipterocarps, while others preferred dead trees. The results of the bait-trap survey also indicated that some species were abundant in the primary forests, whereas other species were abundant in the disturbed forests. These results suggest that human disturbance alters the species composition of the stingless bee community. Such changes in the bee community may affect the reproductive success of plants, and ultimately forest composition.  相似文献   

Heterogeneity of neutral phosphate buffer extractable soil organic matter     

Kae MIYAZAWA  Tohru MURAYAMA 《Soil Science and Plant Nutrition》2007,53(1):1-6

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Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase   总被引：2172，自引：0，他引：2172  

R K Saiki  D H Gelfand  S Stoffel  S J Scharf  R Higuchi  G T Horn  K B Mullis  H A Erlich 《Science (New York, N.Y.)》1988,239(4839):487-491

A thermostable DNA polymerase was used in an in vitro DNA amplification procedure, the polymerase chain reaction. The enzyme, isolated from Thermus aquaticus, greatly simplifies the procedure and, by enabling the amplification reaction to be performed at higher temperatures, significantly improves the specificity, yield, sensitivity, and length of products that can be amplified. Single-copy genomic sequences were amplified by a factor of more than 10 million with very high specificity, and DNA segments up to 2000 base pairs were readily amplified. In addition, the method was used to amplify and detect a target DNA molecule present only once in a sample of 10(5) cells.  相似文献   

Inhibitory effects of oolong tea polyphenols on pancreatic lipase in vitro   总被引：10，自引：0，他引：10  

Nakai M  Fukui Y  Asami S  Toyoda-Ono Y  Iwashita T  Shibata H  Mitsunaga T  Hashimoto F  Kiso Y 《Journal of agricultural and food chemistry》2005,53(11):4593-4598

Fifty-four polyphenols isolated from tea leaves were evaluated for their inhibitory activities against pancreatic lipase, the key enzyme of lipid absorption in the gut. (-)-Epigallocatechin 3-O-gallate (EGCG), which is one of major polyphenols in green tea, showed lipase inhibition with an IC50 of 0.349 microM. Moreover, flavan-3-ol digallate esters, such as (-)-epigallocatechin-3,5-digallate, showed higher activities of inhibition on lipase with an IC50 of 0.098 microM. On the other hand, nonesterified flavan-3-ols, such as (+)-catechin, (-)-epicatechin, (+)-gallocatechin, and (-)-epigallocatechin, showed zero and/or the lowest activities against pancreatic lipase (IC50 > 20 microM). These data suggested that the presence of galloyl moieties within the structure was required for enhancement of pancreatic lipase inhibition. It is well-known that flavan-3-ols are polymerized by polyphenol oxidase and/or heating in a manufacturing process of oolong tea. Oolonghomobisflavans A and B and oolongtheanin 3'-O-gallate, which are typical in oolong tea leaves, showed strong inhibitory activities with IC50 values of 0.048, 0.108, and 0.068 microM, respectively, even higher than that of EGCG. The oolong tea polymerized polyphenols (OTPP) were prepared for the assay from oolong tea extract, from which the preparation effectively subtracted the zero and/or less-active monomeric flavan-3-ols by preparative high-performance liquid chromatography. The weight-average molecular weight (Mw) and number-average molecular-weight (Mn) values of OTPP were 2017 and 903, respectively, by using gel permeation choromatography. OTPP showed a 5-fold stronger inhibition against pancreatic lipase (IC50 = 0.28 microg/mL) by comparison with that of the tannase-treated OTPP (IC50 = 1.38 microg/mL). These data suggested that the presence of galloyl moieties within their chemical structures and/or the polymerization of flavan-3-ols were required for enhancement of pancreatic lipase inhibition.  相似文献