Diurnal rhythm of serum steroid hormone levels in the Japanese whiting,Sillago japonica,a daily-spawning teleost     

Michiya Matsuyama  Shinji Adachi  Yoshitaka Nagahama  Katsuhiko Maruyama  Shuhei Matsura 《Fish physiology and biochemistry》1990,8(4):329-338

Ovarian developmental stages and serum steroid hormone levels were examined at six different times of day (0100, 0600, 1000, 1300, 1600, 2000 h) in a marine teleost, the Japanese whiting Sillago japonica, which has an asynchronous-type ovary containing oocytes at various stages of development and spawns every day during a period ranging up to three months. The largest oocytes in the ovaries at the active vitellogenic or post-vitellogenic stages were found between 0100 and 1300 h. Oocyte maturation indicated by germinal vesicle breakdown (GVBD) occurred at 1600 h, and ovulated oocytes were observed in the ovaries collected at 2000 h. These processes were accompanied by a significant daily change in serum steroid hormone levels. The serum level of estradiol-17β showed a peak in fish with mature oocytes sampled at 1600 h. In these fish, the second-largest oocytes in the ovaries were at the initial stage of vigorous vitellogenesis, the secondary yolk stage. Therefore the highest level of serum estradiol-17β was considered to be due to the second-largest oocytes. Testosterone levels remained low and constant throughout the experimental period. The serum levels of 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-diOHprog) peaked at 1600 h at which time all fish had mature oocytes. These results indicate that the Japanese whiting possesses a diurnal rhythm of oocyte development including vitellogenesis, oocyte maturation and ovulation, and further suggest that daily cycles in oocyte growth and maturation which simultaneously take place in an ovary are regulated by diurnal secretions of estradiol-17β and the maturation-inducing steroid, 17α,20β-diOHprog.  相似文献   

Skeletal development and deformities in cultured larval and juvenile seven-band grouper, Epinephelus septemfasciatus (Thunberg)   总被引：1，自引：0，他引：1  

Naoki Nagano  Akiko Hozawa  Wataru Fujiki  Toshiyuki Yamada  Kadoo Miyaki  Yoshitaka Sakakura  & Atsushi Hagiwara 《Aquaculture Research》2007,38(2):121-130

The seven‐band grouper, Epinephelus septemfasciatus (Thunberg), is currently recognized as a potential new species for aquaculture in Japan. This study describes normal and abnormal skeletal development of the jaw and vertebrae in cultured larvae and early juveniles of E. septemfasciatus. The ontogenetic stages at which skeletal deformities of jaw and vertebra developed were also described for this species. Osteological observations were made using a clearing and staining method for larvae and soft X‐ray photographs for juveniles. A high incidence of skeletal deformities was observed in the jaws and vertebral column during the larval and juvenile stages. Most of the jaw deformities were explained by an abnormal maxilla curvature. Jaw deformities were visually evident from flexion stage after ossification of the deformed elements. Deformities in the vertebral column (mostly lordosis) were observed from the post‐larval stage and became more evident as growth proceeded. The lordosis generally occurred on the positions of the 8–11th vertebra. These types of deformities are compared with those of other species, and possible causative factors of the skeletal deformities are discussed.
  相似文献   

Mechanisms of synthesis and action of 17α,20β-dihydroxy-4-pregnen-3-one,a teleost maturation-inducing substance     

Yoshitaka Nagahama  Masakane Yamashita 《Fish physiology and biochemistry》1989,7(1-6):193-200

This article briefly reviews the current status of investigations, mainly based on the amago salmon,Oncorhynchus rhodurus, on the mechanisms of synthesis and action of 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-diOHprog). Pituitary gonadotropin is of primary importance in triggering meiotic maturation in teleost oocytes. However, the maturational action of gonadotropin is not direct, but is mediated by the follicular production of maturation-inducing substance (MIS). It is now well established that 17α,20β-diOHprog is the major MIS of salmonids. Production of this steroid occursvia the interaction of two distinct cell layers, the thecal and granulosa cell layers (2-cell type model). The first step of the stimulating effect of gonadotropin in both layers is the receptor-mediated activation of adenylate cyclase and formation of cAMP. Our findings suggest that the major stimulating action of gonadotropin on 17α,20β-diOHprog biosynthesis is due to the stimulation of 17α-hydroxyprogesterone production by the thecal layer and the selective induction of thede novo synthesis of 20β-hydroxysteroid dehydrogenase in the granulosa layer. 17α,20β-diOHprog acts at the surface of the oocyte. The early steps following 17α,20β-diOHprog action involve the formation of the major cytoplasmic mediator of this steroid, maturation-promoting factor (MPF). It was shown that goldfish MPF induces meiotic maturation inXenopus oocytes andvice versa. The chemical characterization of fish MPF is important for our understanding of the precise mode of maturational action of 17α,20β-diOHprog.  相似文献   

Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one to oocyte cortices of rainbow trout (Oncorhynchus mykiss)     

Michiyasu Yoshikuni  Naoki Shibata  Yoshitaka Nagahama 《Fish physiology and biochemistry》1993,11(1-6):15-24

Specific binding of [³H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP) to plasma membranes prepared from defolliculated oocytes of rainbow trout (Onchorhynchus mykiss) was identified and characterized. Binding was rapid and reached equilibrium in 30 min. 17α,20β-DP strongly inhibited [³H] 17α,20β-DP binding in a competitive manner. Scatchard analysis revealed two different binding sites: a high affinity binding site with a K_d of 18 nM and a B_max of 0.2 pmoles/mg protein; and a low affinity binding site with a K_d of 0.5 μM and a B_max of 1 pmoles/mg protein. This binding activity was successfully solubilized with n-heptyl-β-D-thioglucoside. [³H]17α,20β-DP binding to solubilized preparations reached equilibrium in 1h, and was competitively inhibited with 17α,20β-DP and 17α,20β,21-trihydroxy-4-pregnen-3-one. However, Scatchard analysis showed a single binding site with a K_d of 0.3 μM. The reason for the disappearance of the high affinity binding site in solubilized preparations remains unclear. These results demonstrate that a specific binding site for 17α,20β-DP exists in the plasma membrane of rainbow trout oocytes.

---

Résumé Une liaison spécifique de le [³H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP), avec des membranes plasmiques d'ovocytes défollicularisés de truite arc-en-ciel (Onchorhynchus mykiss), a été identifiée et caractérisée. Sa cinétique est rapide et atteint son équilibre en 30 minutes. Le 17α,20β-DP inhibe fortement, et de manière compétitive, la liaison de la [³H] 17α,20β-DP. Une étude de Scatchard a mis en évidence deux sites diffŕents de liaison: un site de forte affinité, de K_d 18 nM et de B_max 0,2 pmoles/mg de protéine; et un site de faible affinité, de K_d 0,5 μM et de B_max 1 pmoles/mg de protéine. L'activité de liaison a été solubilisée, avec succés, par le n-heptyl-β-D-thioglucoside. Dans la fraction soluble, la liaison de le [³H]17α,20β-DP atteint un équilibre en 1h.; et elle est complétement inhibiée par la 17α,20β-DP et le 17α,20β,21-trihydroxy-4-pregnen-3-one. Cependant, une étude de Scatchard ne permet de déceler qu'un seul site de liaison, de K_d 0,3 μM. La disparition du site de liaison de forte affinité dans la fraction soluble reste inexpliquée. Ces résultats démontrent l'existence d'un site spécifique de liaison du 17α,20β-DP dans les membranes plasmiques des ovocytes de truite arc-en-ciel.

  相似文献   

Antimutagenic activity of polymethoxyflavonoids from Citrus aurantium   总被引：2，自引：0，他引：2  

Miyazawa M  Okuno Y  Fukuyama M  Nakamura S  Kosaka H 《Journal of agricultural and food chemistry》1999,47(12):5239-5244

The methanol extract from Citrus aurantium showed a suppressive effect on umu gene expression of SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract from C. aurantium was successively re-extracted with hexane, dichloromethane, butanol, and water. A dichloromethane fraction showed a suppressive effect. The suppressive compounds in the dichloromethane fraction were isolated by SiO(2) column chromatography and identified as tetra-O-methylscutellarein (1), sinensetin (2), and nobiletin (3) by EI-MS and (1)H- and (13)C NMR spectroscopy. These compounds suppressed the furylfuramide-induced SOS response in the umu test. Gene expression was suppressed 67%, 45%, and 25% at a concentration of 0.6 micromol/mL, respectively. The ID(50) value (50% inhibition dose) of compound 1 was 0. 19 micromol/mL. These compounds were assayed with other mutagens, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which requires liver metabolizing enzymes, activated Trp-P-1, and UV irradiation. These compounds showed of all mutagen-induced SOS response in the umu test. In addition, compounds 1-3 exhibited antimutagenic activity in the S. typhimurium TA100 Ames test.  相似文献   

A three-dimensional light transfer model based on the vertical point-quadrant method and Monte-Carlo simulation in a Fagus crenata forest canopy on Mount Naeba in Japan     

Atsuhiro Iio  Yoshitaka KakubariHiromi Mizunaga 《Agricultural and Forest Meteorology》2011,151(4):461-479

  相似文献   

Ability of salt glands in Rhodes grass (Chloris gayana Kunth) to secrete Na⁺ and K⁺     

Hidekazu KOBAYASHI  Yoshikuni MASAOKA  Yoshitaka TAKAHASHI  Yasuyuki IDE  Setsuro SATO 《Soil Science and Plant Nutrition》2007,53(6):764-771

  相似文献   

Substrate specificity of the nateglinide/H(+) cotransport system for phenolic acids   总被引：2，自引：0，他引：2  

Saito Y  Itagaki S  Otsuka Y  Kobayashi Y  Okumura H  Kobayashi M  Hirano T  Iseki K 《Journal of agricultural and food chemistry》2005,53(15):6100-6104

In clinical, patients usually take many kinds of drugs at the same time. Thus, drug-drug interactions involving transporters can often directly affect the therapeutic safety and efficacy of many important drugs. However, there have been few studies on food-drug interactions involving transporters. Dietary polyphenols have been widely assumed to be beneficial for human health. Polyphenols are found ubiquitously, and they are commercially prepared and used as functional foods. We have reported that ferulic acid, which is one of the most well-known polyphenols and is used as a functional food, affected the transport of nateglinide, an antidiabetic drug, by Caco-2 cells. In this study, we investigated the effects of other polyphenols on the nateglinide/H(+) transport system. We report here that caffeic acid and p-coumaric acid have a different inhibitory manner on the uptake of nateglinide. The results of this study are useful to identify the substrate specificity of the nateglinide/H(+) cotransporter.  相似文献   

Antimutagenic activity of flavonoids from Pogostemon cablin   总被引：8，自引：0，他引：8  

Miyazawa M  Okuno Y  Nakamura S  Kosaka H 《Journal of agricultural and food chemistry》2000,48(3):642-647

A methanol extract from Pogostemon cablin showed a suppressive effect on umu gene expression of SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract was re-extracted with hexane, dichloromethane, butanol, and water. A dichloromethane fraction showed a suppressive effect. Suppressive compounds against furylfuramide in the dichloromethane fraction were isolated by SiO(2) column chromatography and identified as 7,4'-di-O-methyleriodictyol (1), 7, 3',4'-tri-O-methyleriodictyol (2), and 3,7,4'-tri-O-methylkaempferol (3). In addition, three flavonoids, ombuine (4), pachypodol (5), and kumatakenin (6), were isolated and identified from the dichrolomethane fraction. Compounds 1 and 3 suppressed >50% of the SOS-inducing activity at <0.6 micromol/mL, and the ID(50) values of both compounds were 0.25 micromol/mL. Compound 2 showed a weakly suppressive effect (17%) at a concentration of 0.6 micromol/mL, and compounds 4-6 did not. These compounds were also assayed with 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which requires liver metabolizing enzymes. Compounds 3-6 suppressed >80% of the SOS-inducing activity of Trp-P-1 at <0.06 micromol/mL, and compounds 1 and 2 suppressed 87 and 63% at a concentration of 0.3 micromol/mL. In addition, these compounds were assayed with activated Trp-P-1, and the suppressed effects of these compounds were further decreased when compared to Trp-P-1. The antimutagenic activities of these compounds against furylfuramide, Trp-P-1, and activated Trp-P-1 were assayed by the Ames test using S. typhimurium TA100.  相似文献   

Transformation of humus in upland soils,Japan     

Jiro Kosaka  Chikabumi Honda  Akira Izeki 《Soil Science and Plant Nutrition》2013,59(5):23-28

In the previous reports¹⁾²⁾, we published the significant relationship between methoxyl content and other properties of humus. In order to prove that methoxyl content decreased with the progress of humification and that this amount might be used as an index of the degree of humification, we investigated the deformation of humic acid by acid treatment.  相似文献