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41.
Oze H Hirao M Ebina K Shi K Kawato Y Kaneshiro S Yoshikawa H Hashimoto J 《In vitro cellular & developmental biology. Animal》2012,48(2):123-130
Previous studies have demonstrated that oxygen environment is an important determinate factor of cell phenotypes and differentiation,
although factors which affect pericellular oxygen concentration (POC) in murine chondrogenic cell culture remain unidentified.
Oxygen concentrations in vivo were measured in rabbit musculoskeletal tissues, which were by far hypoxic compared to 20% O2 (ranging from 2.29 ± 1.16 to 4.36 ± 0.51%). Oxygen concentrations in murine chondrogenic cell (C3H10T1/2) culture medium
were monitored in different oxygen concentrations (20% or 5%) in the incubator and in different medium volumes (3,700 or 7,400 μl)
within 25-cm2 flasks. Chondrogenic differentiation was assessed by glycosaminoglycan production with quantitative evaluation of Alcian
blue staining in 12-well culture dishes. Expression of chondrogenic genes, aggrecan, and type II collagen α1, was examined
by quantitative real-time polymerase chain reaction. Oxygen concentrations in medium decreased accordingly with the depth
from medium surface, and POC at Day 6 was 18.99 ± 0.81% in 3,700-μl medium (1,480-μm depth) and 13.26 ± 0.23% in 7,400-μl
medium (2,960-μm depth) at 20% O2 in the incubator, which was 4.96 ± 0.08% (1,480-μm depth) and 2.83 ± 0.42% (2,960-μm depth) at 5% O2, respectively. The differences of POC compared by medium volume were statistically significant (p = 0.0003 at 20% and p = 0.001 at 5%). Glycosaminoglycan production and aggrecan gene expression were most promoted when cultured in moderately
low POC, 1,000 μl (2,960-μm depth) at 20% O2 and 500 μl (1,480-μm depth) at 5% O2 in 12-well culture dishes. We demonstrate that medium volume and oxygen concentration in the incubator affect not only POC
but also chondrogenic differentiation. 相似文献
42.
43.
Irie O Kosaka T Kishida M Sakaki J Masuya K Konishi K Yokokawa F Ehara T Iwasaki A Iwaki Y Hitomi Y Toyao A Gunji H Teno N Iwasaki G Hirao H Kanazawa T Tanabe K Hiestand PC Malcangio M Fox AJ Bevan SJ Yaqoob M Culshaw AJ Hart TW Hallett A 《Bioorganic & medicinal chemistry letters》2008,18(19):5280-5284
We describe here orally active and brain-penetrant cathepsin S selective inhibitors, which are virtually devoid of hERG K(+) channel affinity, yet exhibit nanomolar potency against cathepsin S and over 100-fold selectivity to cathepsin L. The new non-peptidic inhibitors are based on a 2-cyanopyrimidine scaffold bearing a spiro[3.5]non-6-yl-methyl amine at the 4-position. The brain-penetrating cathepsin S inhibitors demonstrate potential clinical utility for the treatment of multiple sclerosis and neuropathic pain. 相似文献
44.
The evolution of self-fertilization from primarily outcrossing ancestors is one of the most common evolutionary transitions in plants; however, the ecological mechanisms that maintain self-fertilization have remained controversial. Theoretical studies suggest that selfing is advantageous over outcrossing in terms of genetic transmission and assurance of seed production under pollen-limited circumstances. Trillium camschatcense is a herbaceous perennial distributed in Hokkaido and northern Honshu, Japan. Geographical variation in the breeding system (self-compatible, SC; or self-incompatible, SI) has been reported in populations in Hokkaido. Here, we used several SC and SI populations of T. camschatcense to investigate the adaptive significance and the evolutionary basis of self-fertilization. Pollination experiments and genetic analyses demonstrated that the potential availability of outcross pollen in SC populations was sufficient and that the number of pollen donors was equal to that of SI populations. However, despite the high availability of outcross pollen, the SC populations produced seeds predominantly by selfing and so underwent severe inbreeding depression. Although none of the suggested advantages for self-fertilization were supported by our analyses, we propose two possible scenarios for the evolution of self-fertilization in T. camschatcense. 相似文献
45.
46.
A triple helical polysaccharide schizophyllan in aqueous solution exhibited a highly cooperative transition between ordered and disordered states associated with the conformation of its side chains and nearby water molecules. The transition was followed by optical rotation and calorimetry using water containing additives such as NaOH and DMSO as solvents. The ordered state was stabilized or destabilized depending on the kind and amount of the additive employed; in particular, the addition of DMSO had a remarkable stabilizing effect. This effect was analyzed by means of a statistical mechanical theory of linear cooperative transitions, where DMSO was assumed to interact favorably with the ordered side chains. A small amount of NaOH in a solvent mixture stabilized the ordered state and made the transition curve very gradual. No molecular mechanism was elucidated to account for the role of NaOH. 相似文献
47.
48.
To investigate which component of the plasma membrane of the hamster egg plays the central role in the sperm–egg fusion, the egg membrane was treated with a variety of proteolytic, carbohydrate-hydrolyzing, lipid-hydrolyzing, and other enzymes. The only enzyme that markedly effected the ability of the egg membrane to fuse with spermatozoa was phospholipase C. The lipid moieties of the egg plasma membrane (and possibly of the sperm membrane) must be of primary importance in sperm–egg fusion at fertilization. 相似文献
49.
Toshihide Hirao Masashi Murakami Jiro Iwamoto Hino Takafumi Hiroyuki Oguma 《Ecological Research》2008,23(1):189-196
The effect of disturbance on local communities may operate within the context of the spatial landscape. We examined the scale-dependent
effects of windthrow disturbance caused by a large typhoon on three arthropod communities in a temperate forest of Japan.
Canopy arthropods were collected by beating foliage, forest-floor arthropods were collected by sweeping the vegetation, and
flying arthropods were collected in Malaise traps. To assess the “functional spatial scale” at which arthropods responded
to tree-fall disturbance, the gap rate was quantified at different spatial scales by sequentially enlarging the radius of
a circular landscape sector in 10-m increments from 10 to 500 m. We then analyzed the responses of order richness and abundance
to the gap rate for each arthropod community. The spatial scale of the significant best-fitting model, which was selected
from the models fitted to the gap rate at stepwise spatial scales, was regarded as the arthropod-specific functional spatial
scale. Arthropod order richness was not dependent on the gap rate. In contrast, arthropod order abundance depended significantly
on the gap rate in many orders, but varied in the response direction and functional spatial scale. These order-specific, scale-dependent
responses to tree-fall gaps could complicate interactions among organisms, leading to complex community organization. An understanding
of the spatial processes that link the use of space by organisms with the spatial scale at which ecological processes are
experienced is required to elucidate the responses of populations, communities, and biotic interactions to disturbances in
a spatial landscape context. 相似文献
50.
M Hirabayashi R Takahashi K Ito N Kashiwazaki M Hirao K Hirasawa S Hochi M Ueda 《Experimental Animals》2001,50(2):125-131
Transgenic mammals, from small laboratory rodents to domestic animals, have been successfully produced to date, but their production efficiency within or across species has been variable. This is probably due to the differences in the type of injected DNA and/or technical procedures employed in each laboratory, as well as the reproductive characteristics of the species. Here we report the direct comparison of the efficiencies of producing transgenic mice, rats, rabbits and pigs by one technician using a fusion gene composed of the bovine alpha S1-casein promoter and human growth hormone (hGH) gene. Before the fusion gene was injected into the zygotes, high magnitude centrifugation to visualize the pronuclei was necessary for all of the pig zygotes and one-third of the rabbit zygotes, but not for mouse and rat zygotes. Post-injection survival of the mouse zygotes (67.1%) was lower than those of the rat, rabbit and pig zygotes (89.6 to 100%). The volume change of the pronucleus following DNA injection was the lowest in mice (50% increase), moderate in rabbits (148% increase), and the most prominent in rats (238% increase). The data from only 1 pig zygote indicated a 22% increase in the pronucleus volume by DNA injection. The PCR analyses of the tail DNA of new born offspring indicated that 0.8% (4/493), 4.8% (22/463), 0.8% (3/367) and 0.9% (2/221) of the injected eggs in mice, rats, rabbits and pigs, respectively, developed into transgenic offspring. Some of the founder animals in all four species expressed the transgene in the mammary gland which was confirmed in hGH mRNA by RT-PCR and/or hGH peptide in Witch's milk with ELISA. These results suggest that the maximum volume of DNA solution injectable into the pronucleus is a possible factor explaining the species differences in the production of transgenic animals. 相似文献