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排序方式: 共有686条查询结果,搜索用时 15 毫秒
91.
Browne P Conley AJ Spraker T Ream RR Lasley BL 《General and comparative endocrinology》2006,147(2):175-183
Recent precipitous population declines in northern fur seal (Callorhinus ursinus) and other Alaskan pinniped populations are due in part to reduced fecundity and have emphasized deficits in basic reproductive knowledge of these species. Following estrus and mating, fertilized female pinnipeds experience an obligatory delayed implantation lasting several months and non-pregnant (pseudopregnant) females are indistinguishable by sex steroid levels during this time. The current study examined circulating steroid concentrations and ovarian expression of key steroid-synthesizing enzymes in northern fur seals to identify changes associated with embryonic implantation, data necessary for estimating early pregnancy rates of the population. Blood samples were collected from 84 female fur seals captured on an Alaskan rookery from October 15 to November 30, a period spanning the end of the delay and subsequent uterine implantation of the fertilized blastocyst in this species. Concentrations of progesterone, estradiol, and estrone measured in blood collected during boreal fall were contrasted with samples collected during late summer from post-ovulatory females and males. Serum sex steroids were also related to ovarian expression of key enzymes responsible for androgen (17alpha-hydroxylase/17,20-lyase, cytochrome b5, and 3beta-hydroxysteroid dehydrogenase) and estrogen (aromatase cytochrome P450) synthesis. Enzymes necessary for androgen synthesis were highly expressed in ovaries, and accordingly, endocrine profiles were expanded to include DHEA, androstenediol, androstenedione, and testosterone. Estradiol concentrations were universally low and free and conjugated estrone were the primary circulating estrogens in fur seal sera. No implantation-associated peak was identified for estrogens or progesterone and mean values of progesterone and estrone were actually greater in female serum samples collected during summer than fall. However, there was a significant positive relationship between fall sampling date and testosterone concentration. Additionally, DHEA concentrations in females were lower in samples collected during the implantation period than during the summer embryonic delay. These data suggest androgens may play a substantial regulatory role in the embryonic delay of northern fur seals. 相似文献
92.
93.
Fibropapillomatosis (FP) of marine turtles is a neoplastic disease of ecological concern. A fibropapilloma-associated turtle herpesvirus (FPTHV) is consistently present, usually at loads exceeding one virus copy per tumor cell. DNA from an array of parasites of green turtles (Chelonia mydas) was examined with quantitative PCR (qPCR) to determine whether any carried viral loads are sufficient to implicate them as vectors for FPTHV. Marine leeches (Ozobranchus spp.) were found to carry high viral DNA loads; some samples approached 10 million copies per leech. Isopycnic sucrose density gradient/qPCR analysis confirmed that some of these copies were associated with particles of the density of enveloped viruses. The data implicate the marine leech Ozobranchus as a mechanical vector for FPTHV. Quantitative RT-PCR analysis of FPTHV gene expression indicated that most of the FPTHV copies in a fibropapilloma have restricted DNA polymerase expression, suggestive of latent infection. 相似文献
94.
目的:对采自中国南海的海绵Axinyssa sp.进行化学成分研究,从中寻找具有生物活性的次生代谢产物。方法:用硅胶和凝胶LH-20柱层析对海绵Axinyssa sp.的乙醚提取物进行分离纯化,并结合现代波谱技术对得到的化合物进行结构鉴定。结果:分离得到了4个化合物,其结构分别鉴定为theonellin isothiocyanate(1),theonellin formamide(2),7-isothiocyanato-7,8-dihydro-α-bisabolene(3)和axinysterol(4)。结论:化合物1-3均为首次从海绵Axinyssa sp.中分离得到,同时也是首次从中国海域的海洋生物中分离得到。 相似文献
95.
目的研究沙蚕消化道产蛋白酶菌D2株胞外蛋白酶对鼠乳腺癌细胞EMT6增殖的影响。方法选用鼠乳腺癌细胞EMT6作为靶细胞,用0.0043-43μmol/L浓度的沙蚕消化道产蛋白酶菌D2株胞外蛋白酶(D2蛋白酶),通过体外细胞培养法进行细胞增殖抑制检测,测其吸光度(OD)值,计算细胞增殖抑制率,与阳性对照组(紫杉醇组)比较。结果实验组OD值低于空白对照组,且存在时间和剂量依赖关系。结论沙蚕消化道产蛋白酶菌D2株胞外蛋白酶对鼠乳腺癌细胞EMT6的增殖存在抑制作用,显示出一定的抗肿瘤活性。 相似文献
96.
Ahmed Atef El-Beih Hikaru Kato Sachiko Tsukamoto Tomihisa Ohta 《Journal of natural medicines》2007,61(2):175-177
More than 50% of clinically used drugs are thought to be metabolized by cytochrome P450 (CYP) 3A4. Discovery of new, inexpensive,
CYP3A4 inhibitors will reduce drug dosages needed to cure patients. In our search for new inhibitors of the enzyme CYP3A4,
extracts from 102 marine fungi were screened. Seven of the extracts had potent CYP3A4 inhibitory activity. Four aromatic compounds
were isolated from an extract of a culture of one of these, a Penicillium sp., and were identified as 3-methoxyphenol (1), 4-methoxyphenylacetic acid (2), 4-(2-hydroxyethyl)phenol (3), and 4-hydroxy-2-methoxyacetanilide (4) by use of spectroscopic data. Interestingly, compound 3 at 250 μg mL−1did not inhibit CYP3A4 whereas compounds 1, 2 and 4 had CYP inhibitory activity with IC50 values of 2.0, 1.6 and 0.41 μg mL−1, respectively. 相似文献
97.
Taiko Oda Weifang Wang Ayako Fujita Masataka Mochizuki Kazuyo Ukai Michio Namikoshi 《Journal of natural medicines》2007,61(4):434-437
An extract of a marine sponge, Hippospongia sp., collected in Palau has inhibitory activity against colony formation by Chinese hamster V79 cells. Bioassay-guided isolation
gave eleven sesquiterpene quinones. Compounds 1–8 inhibited colony formation by V79 cells with EC50 values between 0.6 and 2.8 μmol L−1. Their effects on the production of an inflammatory cytokine, IL-8, in tetradecanoyl phorbol acetate (PMA)-stimulated HL-60
cells were also investigated, because IL-8 production is sometimes correlated with inhibition of cell growth. Ilimaquinone
(1) and its 5 epimer (2) had similar activity against V79 cells (EC50 = 2.8 and 2.3 μmol L−1, respectively) but did not modulate IL-8 production even at 10 μmol L−1. Smenospongidine (3) and its 5 epimer (4), smenospongiarine (5) and its 5 epimer (6), and smenospongine (7) and its 5-epimer (8), at 10 μmol L−1, promoted IL-8 production. Compounds 3, 5, and 7 had slightly stronger activity against V79 cells (EC50 = 0.6, 1.7, and 0.8 μmol L−1, respectively) than the corresponding 5 epimers 4, 6, and 8 (EC50 = 0.8, 2.3, and 2.0 μmol L−1, respectively). A similar structure–activity relationship was observed for promotion of IL-8 production. This is the first
report of modulation of IL-8 production by these sesquiterpene quinones. 相似文献
98.
The cytotoxicity of lingshuiol, a novel polyhydroxy compound with a linear carbon-chain isolated from the cultured marine dinoflagellate Amphidinium sp., and that of amphidinol 2 (AM2) was compared with hepatocytes. Both lingshuiol and AM2 were toxic to primary rat hepatocytes with IC(50) values of 0.21 and 6.4muM, respectively. Meanwhile, lingshuiol or AM2 caused a rapid mitochondrial swelling and leakage of Ca(2+), underlying the change in permeability of mitochondria. Cyclosporin A, a specific inhibitor of mitochondrial permeability transition (MPT), could not affect these effects, indicating that CsA-sensitive MPT was not involved in the permeabilizing effects of lingshuiol or AM2. Sytox green tests further demonstrated that lingshuiol had a much stronger permeabilizing activity than AM2. Taken together, these results disclosed that lingshuiol had potent membrane permeabilizing activities, which might account for its cytotoxic effect. 相似文献
99.
Micronucleus (MN) and other nuclear abnormalities have been measured in the hemocytes of mussels Perna perna to verify whether feeding mussels with different concentrations of Prorocentrum lima results in accumulation of levels of okadaic acid (OA) capable of inducing genotoxic effects at the chromosome level, as evidenced by micronuclei and nuclear abnormalities. Four groups of 12 mussels housed individually in aquaria containing filtered seawater were fed with different concentrations of P. lima. Another group collected directly from the production area served as outdoor control. A significantly higher frequency of MN and nuclear lesions was observed in hemocytes from the groups fed P. lima. 相似文献
100.
《中国海洋药物》杂志刊载论文的引文分析 总被引:1,自引:0,他引:1
采用文献计量学方法,对1989年-1993年《中国海洋药物》杂志刊载论文的引文进行了分析。结果表明,此间共刊载论文181篇,共有引文1301条,每篇论文平均引文量为7.98条。自引率为12.76%,在全部引文中,期刊占65.10%,图书占27.60%,其中占7.30%;语种分布中文占65.72%,英文占29.13%,日文占5.07%,俄文占0.08%。10年文献累计利用率,中文为83.27%,外文 相似文献