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61.
62.
The development of the axial transmission technique now enables in vivo evaluation of cortical bone quality, which plays an important role in bone fragility. Cortical bone is a complex multiscale material, which may be made of different types of microstructure. The interaction between ultrasound and cortical bone remains unclear and most studies have been confined to wave speed analysis. The first aim of this study is to investigate the dependence of the frequency-dependent attenuation on the type of bone microstructure. The second goal is to determine whether broadband ultrasonic attenuation (BUA) is related to volumetric bone mineral density (vBMD) and mass density. Parallelepipedic samples of bovine cortical bone were cut from three specimens and tested in the axial, radial and tangential directions using an ultrasonic transmission device. BUA was evaluated over a 1-MHz wide bandwidth around 4MHz. In addition, the microstructure of each sample was determined using an optical microscope. BUA values measured in porotic microstructure are significantly higher than in Haversian microstructure. The lowest BUA values are obtained for plexiform microstructure. For all structures, BUA in the axial direction is significantly smaller than in the radial and tangential directions. Moreover, BUA is correlated with both vBMD and density (determination coefficient (R2) equal to 0.44 and 0.65, respectively, in the axial direction). BUA variations can be explained by scattering and viscoelastic mechanisms. This study suggests that BUA measurements have the potential to discriminate among different cortical bone microstructures in addition to providing material properties. 相似文献
63.
Yamamoto M Unzai S Saijo S Ito K Mizutani K Suno-Ikeda C Yabuki-Miyata Y Terada T Toyama M Shirouzu M Kobayashi T Kakinuma Y Yamato I Yokoyama S Iwata S Murata T 《The Journal of biological chemistry》2008,283(28):19422-19431
The vacuolar ATPase (V-ATPase) is composed of a soluble catalytic domain and an integral membrane domain connected by a central stalk and a few peripheral stalks. The number and arrangement of the peripheral stalk subunits remain controversial. The peripheral stalk of Na+-translocating V-ATPase from Enterococcus hirae is likely to be composed of NtpE and NtpF (corresponding to subunit G of eukaryotic V-ATPase) subunits together with the N-terminal hydrophilic domain of NtpI (corresponding to subunit a of eukaryotic V-ATPase). Here we purified NtpE, NtpF, and the N-terminal hydrophilic domain of NtpI (NtpI(Nterm)) as separate recombinant His-tagged proteins and examined interactions between these three subunits by pulldown assay using one tagged subunit, CD spectroscopy, surface plasmon resonance, and analytical ultracentrifugation. NtpI(Nterm) directly bound NtpF, but not NtpE. NtpE bound NtpF tightly. NtpI(Nterm) bound the NtpE-F complex stronger than NtpF only, suggesting that NtpE increases the binding affinity between NtpI(Nterm) and NtpF. Purified NtpE-F-I(Nterm) complex appeared to be monodisperse, and the molecular masses estimated from analytical ultracentrifugation and small-angle x-ray scattering (SAXS) indicated that the ternary complex is formed with a 1:1:1 stoichiometry. A low resolution structure model of the complex produced from the SAXS data showed an elongated "L" shape. 相似文献
64.
Mycorrhizal fungi were isolated from the nonphotosynthetic orchid Chamaegastrodia sikokiana and identified as members of Ceratobasidiaceae by phylogenetic analysis of the internal transcribed spacer (ITS) region of
ribosomal deoxyribonucleic acid. The ITS sequences were similar among geographically separated samples obtained from Mt. Kiyosumi
in Chiba Prefecture and Mt. Yokokura in Kochi Prefecture. One of the isolated fungi, KI1-2, formed ectomycorrhiza on seedlings
of Abies firma in pot culture, suggesting that tripartite symbiosis exists among C. sikokiana, mycorrhizal fungi, and A. firma in nature, and carbon compounds are supplied from A. firma to C. sikokiana through the hyphae of the mycorrhizal fungi. To our knowledge, this is the second study to suggest the involvement of Ceratobasidiaceae
fungi in tripartite symbiosis with achlorophyllous orchids and photosynthetic host plants. 相似文献
65.
A community of arbuscular mycorrhizal (AM) fungi was investigated in a warm-temperate deciduous broad-leaved forest using
a molecular analysis method. Root samples were obtained from the forest, and DNA was extracted from the samples. Partial 18S
rDNA of AM fungi were amplified from the extracted DNA by polymerase chain reaction using a universal eukaryotic primer NS31
and an AM fungal-specific primer AM1. After cloning the PCR products, 394 clones were obtained in total, which were divided
into five types by restriction fragment length polymorphism (RFLP) with HinfI, RsaI, and Hsp92II. More than 20% of the clones were randomly selected from each RFLP type and sequenced. Phylogenetic analysis showed that
all the obtained clones belonged to Glomus but could not be identified at species level. Topsoil of the forest containing plant roots was inoculated to nonmycorrhizal
seedlings of indigenous woody plants, Rhus javanica var. roxburghii and Clethra barvinervis, to introduce the community of AM fungi into the seedlings. Among these five RFLP types, four types were detected from both
seedlings, which indicates that the AM fungal community in the forest root samples was introduced at least partly into the
seedlings. Meanwhile, an additional four types that were not found in the forest root samples were newly detected in the seedlings,
these types were closely related to one another and close to G. fasciculatum or G. intraradices. It is expected that a community of indigenous diverse AM fungi could be introduced into target fields by planting these
mycorrhizal seedlings. 相似文献
66.
Youhei Murakami Shin Kamiyama Zakir H Howlader Tokuhisa Yamato Michio Komai Yuji Furukawa 《Journal of biochemistry》2002,131(1):17-19
We tried to confirm the antioxidative capability of lecithin:cholesterol acyltransferase (LCAT) reported by Vohl et al. [Biochemistry (1999) 38, 5976-5981]. The enzyme solution protected LDL against oxidation. However, this protection was not due to LCAT enzyme, but to some unknown low-molecular-weight substance(s) in the solution; LCAT itself exerted little protective effect against LDL oxidation. 相似文献
67.
Fusao Ota Masayuki Yamato Mie Hayashi Masayuki Ota Tetsuro Koga Ahmed Sherin Chiharu Mukai Kentaro Sakai Shigeru Yamamoto 《Microbiological research》2002,157(4):305
Twenty four reference strains (serotype a-h) belonging to the mutans group of streptococci were compared for DNA fragment patterns of rDNA after treatment with Hind III. It was shown that Streptococcus cricetus (serotype a), S. rattus (serotype b), and S. downei (serotype h) reveals comparatively homogeneous patterns while S. mutans (serotype c, e and f) exhibits differences between the different serotypes as well as within single serotypes. S. sobrinus had an intermediary diversity. These data support the previous findings that S. mutans is heterogeneous at the serological, biochemical and genetical level. 相似文献
68.
69.
Emiko Nishi Nami Suzuki-Hashido Takashi Hayakawa Yamato Tsuji Bambang Suryobroto Hiroo Imai 《Primates; journal of primatology》2018,59(6):523-530
For many primates, sweet taste is palatable and is an indicator that the food contains carbohydrates, such as sugars and starches, as energy sources. However, we have found that Asian colobine monkeys (lutungs and langurs) have low sensitivity to various natural sugars. Sweet tastes are recognized when compounds bind to the sweet taste receptor TAS1R2/TAS1R3 in the oral cavity; accordingly, we conducted a functional assay using a heterologous expression system to evaluate the responses of Javan lutung (Trachypithecus auratus) TAS1R2/TAS1R3 to various natural sugars. We found that Javan lutung TAS1R2/TAS1R3 did not respond to natural sugars such as sucrose and maltose. We also conducted a behavioral experiment using the silvery lutung (Trachypithecus cristatus) and Hanuman langur (Semnopithecus entellus) by measuring the consumption of sugar-flavored jellies. Consistent with the functional assay results for TAS1R2/TAS1R3, these Asian colobine monkeys showed no preference for sucrose or maltose jellies. These results demonstrate that sweet taste sensitivity to natural sugars is low in Asian colobine monkeys, and this may be related to the specific feeding habits of colobine monkeys. 相似文献
70.
Taisuke Togawa Tohru Adachi Daijiro Harada Tasuku Mitani Daisuke Tanaka Kimitsune Ishizaki Takayuki Kohchi Katsuyuki T. Yamato 《Journal of plant research》2018,131(6):1047-1054
The liverwort Marchantia polymorpha has become one of the model organisms, since it has less genetic redundancy, sexual and asexual modes of reproduction and a range of genomic and molecular genetic resources. Cryopreservation of fertile spermatozoa eliminates time, space and labor for growing and maintaining male plants in reproductive phase, and also provides an optional way to backup lines. Here we report a protocol to cryopreserve spermatozoa of M. polymorpha in liquid nitrogen. A cryoprotective solution containing sucrose, glycerol and egg yolk and controlled cooling and warming processes led to successful recovery of motile M. polymorpha spermatozoa after the cryogenic process. The survival rate and average motility of spermatozoa after cryopreservation were maintained at 71 and 54% of those before cryopreservation, respectively. Cryopreserved spermatozoa were capable of fertilization to form normal spores. The technique presented here confers more versatility to experiments using M. polymorpha and could be applied to preservation of plant spermatozoa in general. 相似文献