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排序方式: 共有89条查询结果,搜索用时 15 毫秒
81.
Makoto T. Fujiwara Haruki Hashimoto Yusuke Kazama Tomonari Hirano Yasushi Yoshioka Seishiro Aoki Naoki Sato Ryuuichi D. Itoh Tomoko Abe 《Protoplasma》2010,242(1-4):19-33
The behaviour and multiplication of pollen plastids have remained elusive despite their crucial involvement in cytoplasmic inheritance. Here, we present live images of plastids in pollen grains and growing tubes from transgenic Arabidopsis thaliana lines expressing stroma-localised FtsZ1–green-fluorescent protein fusion in a vegetative cell-specific manner. Vegetative cells in mature pollen contained a morphologically heterogeneous population of round to ellipsoidal plastids, whilst those in late-developing (maturing) pollen included plastids that could have one or two constriction sites. Furthermore, plastids in pollen tubes exhibited remarkable tubulation, stromule (stroma-filled tubule) extension, and back-and-forth movement along the direction of tube growth. Plastid division, which involves the FtsZ1 ring, was rarely observed in mature pollen grains. 相似文献
82.
Progesterone treatment of boar spermatozoa improves male pronuclear formation after intracytoplasmic sperm injection into porcine oocytes 总被引:1,自引:0,他引:1
Boar spermatozoa were prepared for intracytoplasmic sperm injection (ICSI) by two different treatments to facilitate sperm chromatin decondensation and improve fertilisation rates after ICSI in pigs: spermatozoa were either frozen and thawed without cryoprotectants, or treated with progesterone. Morphological changes of the sperm heads after the treatments were examined and then the activation of oocytes and the transformation of the sperm nucleus following ICSI were assessed. After freezing and thawing, the plasma membrane and acrosomal contents over the apical region of sperm head were lost in all the spermatozoa. Following treatment with 1 mg/ml progesterone, the acrosome reaction was induced in 61% of spermatozoa. After injection of three types of spermatozoa, non-treated spermatozoa and progesterone-treated (i.e. acrosome-reacted) spermatozoa induced oocyte activation, but frozen-thawed spermatozoa induced oocyte activation at a significantly lower rate. Sixty-two per cent of sperm heads remained orcein-negative for 6 h, however, resulting in delayed sperm chromatin decondensation and low male pronuclear formation in the oocytes injected with a non-treated spermatazoon. Since the treatments of freezing and thawing and progesterone for spermatozoa accelerated the initial change in sperm chromatin and the latter treatment induced oocyte activation earlier, it is considered that the delay in oocyte activation and decondensation of sperm chromatin after injection of non-treated spermatozoa is caused by the existence of the sperm plasma membrane. These results show that progesterone treatment efficiently induces the acrosome reaction in boar spermatozoa without destroying their potency for oocyte activation, and the induction of the acrosome reaction results in the promotion of male pronuclear formation after ICSI. 相似文献
83.
A Tachibana S Yonei 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1985,47(6):663-671
Membrane-specific drugs such as procaine and chlorpromazine have been shown to inhibit excision repair of DNA in u.v.-irradiated E. coli. One possible mechanism is that, if association of DNA with the cell membrane is essential for excision repair, this process may be susceptible to drugs affecting the structure of cell membranes. We examined the effect of phenethyl alcohol, which is a membrane-specific drug and known to dissociate the DNA-membrane complex, on excision repair of DNA in u.v.-irradiated E. coli cells. The cells were irradiated with u.v. light and then held at 30 degrees C in buffer (liquid-holding) in the presence or absence of phenethyl alcohol. It was found that phenethyl alcohol inhibits the liquid-holding recovery in both wild-type and recA strains, corresponding to its dissociating action on the DNA-membrane complex. Thus, the association of DNA with cell membrane is an important factor for excision repair in E. coli. Procaine did not show the dissociating effect, suggesting that at least two different mechanisms are responsible for the involvement of cell membrane in excision repair of DNA in E. coli. 相似文献
84.
85.
Tokumoto Yuji Hashimoto Kayo Soyano Takashi Aoki Seishiro Iwasaki Wataru Fukuhara Mai Nakagawa Tomomi Saeki Kazuhiko Yokoyama Jun Fujita Hironori Kawaguchi Masayoshi 《Journal of plant research》2021,134(4):885-885
Journal of Plant Research - A correction to this paper has been published: https://doi.org/10.1007/s10265-021-01295-3 相似文献
86.
S Yonei T Todo M Kato 《International journal of radiation biology and related studies in physics, chemistry, and medicine》1979,35(2):161-170
The changes in the intrinsic fluorescence, primarily from tryptophan residues, of sheep erythrocyte membranes following X-irradiation (0--4000 R) were investigated. The experiments showed that there was (1) a decrease in the intensity of fluorescence with increasing dose of X-rays, (2) a small shift of fluorescence emission to longer wavelengths, (3) a decrease in the fluorescence polarization, and that (4) treatment of membranes with a perturbing solvent, 2-chloroethanol, can eliminate the effects of X-rays. The amount of tryptophan in the membranes was not altered after X-irradiation. It was also shown that sulphydryl reagents, N-ethylmaleimide and 2,2'-dithiodipyridine, induced similar fluorescence changes. From these results it was concluded that the fluorescence changes could result from a change in the environment surrounding tryptophan residues, from being relatively non-polar to being more polar, implying that conformational changes of membrane proteins are brought about by low doses of X-rays. 相似文献
87.
88.
Seishiro Furukawa Ryo Kawabe Seiji Ohshimo Ko Fujioka Gregory N. Nishihara Yuichi Tsuda Takashi Aoshima Hisao Kanehara Hideaki Nakata 《Environmental Biology of Fishes》2011,92(1):89-99
Environmental changes influence foraging behavior for most animals. Dolphinfish, Coryphaena hippurus, are epipelagic predators and have a cosmopolitan tropical to warm-temperate (>20°C) distribution. We simultaneously obtained
the ambient temperature and the foraging behavior (i.e., swimming speed, depth and tailbeat acceleration) of dolphinfish,
using an acceleration data-logger in May, September, October, November 2007, June 2008, May and July 2010 for 8 individuals.
Although the dolphinfish spent a mean ± standard deviation of 43.4 ± 27.7% of their time at the surface (0–5 m), dive excursions
from the surface (DES) were observed in all individuals and maximum DES depths ranged from 50.1 to 95.4 m. DES events resulted
dives below the thermocline for these dolphinfish, and there was a significantly positive relationship between the isothermal
layer depth (ILD) and DES depth. Our results demonstrate that dolphinfish avoided the rapid thermal change beyond the thermocline,
and their prey is most likely found in the upper layers of the thermocline. Gliding behavior during the DES phase was also
observed and dolphinfish gradually descended to deeper waters with gliding. The gliding time was longer when the ILD was deeper,
and fish tended to dive deeper. We suggest that dolphinfish adopt gliding behavior to search a broader range of depths for
prey, while minimizing energy use. 相似文献
89.