Role for piRNAs and noncoding RNA in de novo DNA methylation of the imprinted mouse Rasgrf1 locus     

Watanabe T  Tomizawa S  Mitsuya K  Totoki Y  Yamamoto Y  Kuramochi-Miyagawa S  Iida N  Hoki Y  Murphy PJ  Toyoda A  Gotoh K  Hiura H  Arima T  Fujiyama A  Sado T  Shibata T  Nakano T  Lin H  Ichiyanagi K  Soloway PD  Sasaki H 《Science (New York, N.Y.)》2011,332(6031):848-852

Genomic imprinting causes parental origin-specific monoallelic gene expression through differential DNA methylation established in the parental germ line. However, the mechanisms underlying how specific sequences are selectively methylated are not fully understood. We have found that the components of the PIWI-interacting RNA (piRNA) pathway are required for de novo methylation of the differentially methylated region (DMR) of the imprinted mouse Rasgrf1 locus, but not other paternally imprinted loci. A retrotransposon sequence within a noncoding RNA spanning the DMR was targeted by piRNAs generated from a different locus. A direct repeat in the DMR, which is required for the methylation and imprinting of Rasgrf1, served as a promoter for this RNA. We propose a model in which piRNAs and a target RNA direct the sequence-specific methylation of Rasgrf1.  相似文献   

Polymerizing actin fibers position integrins primed to probe for adhesion sites     

Galbraith CG  Yamada KM  Galbraith JA 《Science (New York, N.Y.)》2007,315(5814):992-995

Migrating cells extend protrusions, probing the surrounding matrix in search of permissive sites to form adhesions. We found that actin fibers polymerizing along the leading edge directed local protrusions and drove synchronous sideways movement of beta1 integrin adhesion receptors. These movements lead to the clustering and positioning of conformationally activated, but unligated, beta1 integrins along the leading edge of fibroblast lamellae and growth cone filopodia. Thus, rapid actin-based movement of primed integrins along the leading edge suggests a "sticky fingers" mechanism to probe for new adhesion sites and to direct migration.  相似文献   

A rubberlike stretchable active matrix using elastic conductors     

Sekitani T  Noguchi Y  Hata K  Fukushima T  Aida T  Someya T 《Science (New York, N.Y.)》2008,321(5895):1468-1472

By using an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, we uniformly dispersed single-walled carbon nanotubes (SWNTs) as chemically stable dopants in a vinylidene fluoride-hexafluoropropylene copolymer matrix to form a composite film. We found that the SWNT content can be increased up to 20 weight percent without reducing the mechanical flexibility or softness of the copolymer. The SWNT composite film was coated with dimethyl-siloxane-based rubber, which exhibited a conductivity of 57 siemens per centimeter and a stretchability of 134%. Further, the elastic conductor was integrated with printed organic transistors to fabricate a rubberlike active matrix with an effective area of 20 by 20 square centimeters. The active matrix sheet can be uniaxially and biaxially stretched by 70% without mechanical or electrical damage. The elastic conductor allows for the construction of electronic integrated circuits, which can be mounted anywhere, including arbitrary curved surfaces and movable parts, such as the joints of a robot's arm.  相似文献   

Activation of FOXO1 by Cdk1 in cycling cells and postmitotic neurons     

Yuan Z  Becker EB  Merlo P  Yamada T  DiBacco S  Konishi Y  Schaefer EM  Bonni A 《Science (New York, N.Y.)》2008,319(5870):1665-1668

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Imaging doped holes in a cuprate superconductor with high-resolution Compton scattering     

Sakurai Y  Itou M  Barbiellini B  Mijnarends PE  Markiewicz RS  Kaprzyk S  Gillet JM  Wakimoto S  Fujita M  Basak S  Wang YJ  Al-Sawai W  Lin H  Bansil A  Yamada K 《Science (New York, N.Y.)》2011,332(6030):698-702

The high-temperature superconducting cuprate La(2-x)Sr(x)CuO(4) (LSCO) shows several phases ranging from antiferromagnetic insulator to metal with increasing hole doping. To understand how the nature of the hole state evolves with doping, we have carried out high-resolution Compton scattering measurements at room temperature together with first-principles electronic structure computations on a series of LSCO single crystals in which the hole doping level varies from the underdoped (UD) to the overdoped (OD) regime. Holes in the UD system are found to primarily populate the O 2p(x)/p(y) orbitals. In contrast, the character of holes in the OD system is very different in that these holes mostly enter Cu d orbitals. High-resolution Compton scattering provides a bulk-sensitive method for imaging the orbital character of dopants in complex materials.  相似文献   

湖羊起源及系统地位的研究   总被引：14，自引：0，他引：14  

耿荣庆  常洪  杨章平 《西北农林科技大学学报(自然科学版)》2002,30(3):21-24

应用中心产区典型群简单随机抽样法 ,检测控制血液酶和其他蛋白质变异的 14个结构基因座上31个等位基因的频率 ,并引用国内外 2 2个绵羊群体 11个座位的研究资料 ,以探讨湖羊的起源及系统地位。研究表明 ,湖羊与蒙古利亚的绵羊群体亲缘关系相对较近 ,两者可能在更早的世代具有共同的起源。这个结果与已知的历史事实吻合。  相似文献   

Curing and degradation processes of cement-bonded particleboard by supercritical CO<Subscript>2</Subscript> treatment     

Rohny Setiawan Maail  Kenji Umemura  Hideo Aizawa  Shuichi Kawai 《Journal of Wood Science》2011,57(4):302-307

This study examined the effects of supercritical CO₂ treatment on the curing and degradation of cementbonded particleboard (CBP). Significant correlations were found between the supercritical CO₂ treatment and mechanical properties during both curing and degradation processes. Internal bond (IB) strength, modulus of rupture (MOR), and modulus of elasticity (MOE) values of CBP achieved their maximums by supercritical CO₂ treatment in 30 min. These conditions indicated that supercritical CO₂ treatment accelerates the curing process rapidly and enhances the mechanical properties of the CBP. However, these values decreased in treatment from 60 min to 10 days and had a negative effect on board performance, indicating that supercritical CO₂ treatment over a longer time span leads to degradation of the CBP. Furthermore, X-ray diffractometry (XRD), thermal gravimetry (TG-DTG), and scanning electron microscopy (SEM) observation clarified that the mechanisms of degradation are directly affected by the mineralogical composition of the system, in par ticular, by the calcium carbonate content as caused by carbonation.  相似文献   

Fatty acid composition of ruminal bacteria and protozoa,and effect of defaunation on fatty acid profile in the rumen with special reference to conjugated linoleic acid in cattle     

Halima SULTANA  Kenji MIYAZAWA  Shuhei KANDA  Hisao ITABASHI 《Animal Science Journal》2011,82(3):434-440

Objectives of this study were to compare fatty acid (FA) composition of ruminal bacterial (B) and protozoal (P) cells, and to investigate effect of protozoa on FA profile in the rumen of cattle. Three cows were used to prepare ruminal B and P cells. Four faunated and three defaunated cattle (half‐siblings) were used to study effect of protozoa on ruminal FA profile. Proportions of C16:0 and C18:0 in total fatty acids in B cells were 20.7% and 37.4%, whereas those in P cells were 33.4% and 11.6%, respectively. Proportions of trans‐vaccenic acid (VA) and cis‐9, trans‐11 conjugated linoleic acid (CLA) in B cells were 3.9% and 1.0%, and those in P cells were 5.5% and 1.6%, respectively, being higher in P cells. Proportions of C18:1, C18:2 and C18:3 in P cells were two to three times higher than in B cells. Proportions of unsaturated fatty acids, VA and CLA in B cells of faunated cattle were higher than those of defaunated. VA and CLA in the ruminal fluid of faunated were also 1.6 to 2.5 times higher than those of defaunated. This tendency was similar for cell‐free fraction of ruminal fluid. These results indicate that protozoa contribute greatly in VA and CLA production in the rumen.  相似文献   

Effects of growth and dietary crude protein level until first insemination on milk production during first lactation in Holstein heifers     

Takashige ISHII  Kenji KAWASHIMA  Haruo ORIBE  Hiromi UEDA  Toshiya HASUNUMA  Kiyoshi AKIYAMA  Hirofumi NAKAYAMA  Mitsunori KURIHARA  Fuminori TERADA  Shiro KUSHIBIKI 《Animal Science Journal》2011,82(6):741-746

To decrease the age at first calving in Holsteins, the effects of average daily body weight gain (ADG) and crude protein (CP) level until first insemination on growth performance and milk production were examined. The MM group had a target ADG of 0.75 kg and received a diet with a CP level of 14%. The HM and HH groups had a target ADG of 1 kg; both these groups received a diet with CP levels 14% and 16%, respectively. The ADG in the HM and HH groups was 1.1 kg, whereas in the MM group it was 0.97 kg (P < 0.01). The HM and HH groups showed no differences in withers height at body weight 350 kg. The ages at first calving in MM, HM and HH groups were 23.1, 21.0 and 21.8 months, respectively. The HM and HH groups had lower milk yield at day 305 than the MM group (P < 0.01). These results suggest that growth performance until first insemination should be maintained at an ADG of 0.97 kg or less with a CP level of approximately 14%, to shorten time until first insemination and prevent the decrease of milk yield.  相似文献   

Virtopsy in a red kangaroo with oral osteomyelitis     

Lee KJ  Sasaki M  Miyauchi A  Kishimoto M  Shimizu J  Iwasaki T  Miyake Y  Yamada K 《Journal of zoo and wildlife medicine》2011,42(1):128-130

This report describes the use of computed tomography (CT) in a nondomestic species. Postmortem CT was performed on a red kangaroo (Macropus rufus) and a diagnosis of oral osteomyelitis was made. CT examination revealed bony remodeling of the right mandible, an intraosseous lesion of the right temporal bone, muscle necrosis around the right mandible, and the absence of the right, first, upper molar tooth. Cardiac and intrahepatic gas and a distended intestine due to postmortem gas accumulation were also seen. All the lesions identified with CT were also identified by conventional necropsy, except the cardiac and intrahepatic gases. Virtopsy may be a useful procedure for the noninvasive identification of cause of death and as a guide for necropsy in animals.  相似文献