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241.
Mamoru Suzuki Tsuyomi Miyahara Ryuzo Yoshioka Muneji Miyoshi Kazuo Matsumoto 《Bioscience, biotechnology, and biochemistry》2013,77(9):1709-1715
α-Methyltryptophan, α-methylhistidine, and α-methyldopa were prepared by the reaction of α-isocyanopropionates with gramine methiodide, the acetoxymethylimidazole derivative, and protected 3,4-dihydroxybenzyl bromides, respectively. 相似文献
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In nonhuman primates (NHPs), there have so far been few reports about nuclear transfer (NT), especially using adult somatic
cells. The objective of this study was to determine the developmental competence of NT embryos derived from various somatic
cells embryonic stem (ES), amniotic epithelial, cumulus, or fetal fibroblast cells] and the nuclear transfer method, such
as electro fusion or piezo microinjection, activation with chemical reagent [ionomycine/6-dimethylaminopurine (DMAP), calcium
ionophore A23187/DMAP, or cycloheximide (CHX)] and reprogramming time (1, 2, or 4 h; in this study, the duration from injection
or fusion to activation was defined as the reprogramming time). Our results showed that a 1-h reprogramming and activation
with ionomycin/DMAP are suitable for NT in monkeys. Developing cleaved embryos up to the six-cell stage was similar among
all experiments. However, beyond the eight-cell stage, developmental rates were higher in NT embryos reconstructed with fetal
fibroblast cells and amniotic epithelial cells, and we were able to produce NT blastocysts from these cells. Interestingly,
electro fusion is sufficient for amniotic epithelial cells and piezo microinjection is better suited for fetal fibroblast
cells to produce NT blastocysts, thus suggesting that the best method for somatic cell NT may be different between cell types. 相似文献
246.
Senda S Wakayama T Arai Y Yamazaki Y Ohgane J Tanaka S Hattori N Yanagimachi R Shiota K 《Cloning and stem cells》2007,9(3):293-302
Cloned animals have various health problems. Aberrant DNA methylation is a possible cause of the problems. Restriction landmark genomic scanning (RLGS) that enabled us to analyze more than 1,000 CpG islands simultaneously demonstrated that all cloned newborns had aberrant DNA methylation. To study whether this aberration persists throughout the life of cloned individuals, we examined genome-wide DNA methylation status of newborn (19.5 dpc, n=2), adult (8-11 months old, n=3), and aged (23-27 months old, n=4) cloned mice using kidney cells as representatives. In the adult and aged groups, cloning was repeated using cumulus cells of the adult founder clone of each group as nucleus donor. Two newborn clones had three with aberrantly methylated loci, which is consistent with previous reports that all cloned newborns had DNA methylation aberrations. Interestingly, we could detect only one aberrantly methylated locus in two of the three adult clones in mid-age and none of four senescent clones, indicating that errors in DNA methylation disappear with advancement of animals' aging. 相似文献
247.
H Aoshima S J Hossain H Imamura R Shingai 《Bioscience, biotechnology, and biochemistry》2001,65(9):2070-2077
To study the effects of bisphenol-A (BPA) known to have estrogenic actions, and its derivatives, 3,5-dimethylphenol (DMP) and p-t-butylphenol (TBP), on ionotropic gamma-aminobutyric acid (GABA) receptors, GABA(A) receptors were expressed in Xenopus oocytes by injecting both poly(A)+ RNA prepared from rat whole brain and cRNAs synthesized from cloned cDNAs of alpha1 and beta1 subunit of the bovine receptors, and their electrical responses were measured by the voltage clamping method. BPA caused the potentiation and inhibition of the former receptor-responses, while it caused only inhibition of the latter ones. In the presence of low concentrations of GABA, DMP and TBP potentiated the responses of both receptors. DMP and TBP also increased the rate of decay of the response, possibly by desensitization of the receptors when GABA solution was continuously bath-applied. Diethyl terephthalate (DTP), which is also known to have estrogenic actions, had little effect on both the responses and the decay of both receptors. 相似文献
248.
Amitabha Bhattacharyya Eduardo R. S. Roldan Ryuzo Yanagimachi 《Molecular reproduction and development》1986,15(4):285-294
The majority of the spermatozoa precapacitated in Ca2+-free medium underwent the acrosome raction rapidly when they were transferred to Ca2+-containing medium. The presence of Na+ and Ca2+ in the medium was essential for the acrosome reaction. The vast majority of spermatozoa failed to undergo the reaction in Ca2+ medium lacking monovalent ions, although they remained motile. At the concentration of 140 mM, Na+, K+, Rb+, and Cs+ all supported the reaction at the maximum level, but at 50 mM the latter three ions were not as effective as Na+. Li+ was least effective in supporting the reaction. Virtually no acrosome reactions took place when precapacitated spermatozoa were first exposed to Na+ medium (no Ca2+) and then to Ca2+ medium (no Na+). On the other hand, a considerably higher proportion of spermatozoa acrosome reacted when they were exposed to these media in the reverse order. The most efficient acrosome reactions took place when the medium contained both a monovalent ion (Na+) and Ca2+ simultaneously. Possible mechanisms by which monovalent and divalent cations participate in the acrosome reaction are discussed. 相似文献
249.
Ryuzo Torii Hitoshi Koizumi Yoshikuni Tanioka Toshio Inaba Junichi Mori 《Primates; journal of primatology》1987,28(2):229-238
In the ovarian cycle of common marmosets, serum progesterone began to increase at two to three days after estradiol-17β or
LH surge, attained a peak of 25–70 ng/ml and then declined to a level of under 2 ng/ml before the ensuing rise in estradiol-17β
and LH. Serum estradiol-17β increased to 700–5,500 pg/ml during the luteal phase, synchronizing with progesterone. It is suggested
that the corpus luteum secreted estradiol-17β as well as progesterone. The cycle length as determined from the interval between
successive LH surges was approximately 28 days. During the luteal phase, the levels of progesterone and estradiol-17β were
higher than in Old World monkeys and women, but marmosets were not accompanied by any clinical symptoms due to excessive progesterone
and estradiol-17β. This suggests that such unresponsiveness to progesterone and estradiol-17β in marmosets reflects the small
amount of estradiol-17β receptor and presumably also the lower function of the post receptor system.
Recovery of the post-partum ovarian cycle in two marmosets differed from that observed in Old World monkeys and women. The
first LH surge was found on the ninth and tenth day after parturition and the first ovulation led to the next pregnancy. This
suggests that the suckling stimulus of newborns in the common marmoset does not cause any delay in recovery of the ovarian
cycle. In three cases of abortion, the recovery of the ovarian cycle was almost the same as that in the case of normal parturition:
the first LH surge appeared on the 10th, 14th, and 34th day after abortion. 相似文献
250.
Ryuzo Yanagimachi Gary N. Cherr Muralidharan C. Pillai John D. Baldwin 《Development, growth & differentiation》1992,34(4):447-461
When the micropyle area of salmonid (trout and salmon) eggs was observed continuously from the moment of insemination, spermatozoa were seen moving along the surface of the chorion and entering the micropyle one by one in a directed fashion. The ability of spermatozoa to enter the micropyle was reduced after the treatment of chorions with pronase; this reduction in sperm entry was observed even before the outer opening of the micropyle channel was narrowed due to gradual swelling of the chorion by pronase treatment. Herring spermatozoa, unlike spermatozoa of most other marine fishes, were motionless in seawater. However, they became vigorously motile on contact with the micropyle area of the herring egg chorion and entered the micropyle rapidly and efficiently. Motility initiation of herring spermatozoa in the micropyle area was dependent on extracellular calcium and potassium. Sodium also appears to be intricately involved in this process as demonstrated by the initiation of sperm movement in sodium-free seawater. When herring eggs were treated with acidic seawater, organic solvents, or glutaraldehyde, spermatozoa did not initiate movement in the micropyle area, and sperm entry was not observed. Herring spermatozoa did not initiate movement in the micropyle area of salmonid eggs. These and other observations suggest that the micropyle areas of salmonid and herring eggs possess some sperm guidance factors which facilitate entry of homologous spermatozoa into the micropyle. 相似文献