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1.
Honeybee‐assisted wind pollination in bamboo Phyllostachys nidularia (Bambusoideae: Poaceae)? 总被引:1,自引:0,他引:1
SHUANG-QUAN HUANG HUN-FENG YANG IN LU YOSHITAKA TAKAHASHI 《Botanical journal of the Linnean Society. Linnean Society of London》2002,138(1):1-7
Floral syndromes and pollination of three species of Phyllostachys bamboos were studied in Central China in 1999 and 2000. All were protogynous. Stigmas were receptive and had pollen deposited on them 2 days before anther dehiscence. The period of anthesis in the three bamboos was 3 days. Individual pollen grains of the three species were similar in size (30–40 μm in diameter) and had features typical of wind-pollinated plants. The ratios of pollen to ovules (p/o ratio) in P . nidularia , P . heteroclada and P . nuda were 6500, 12 700 and 33 000, respectively. Mean pollen loads on each flower (one ovule) of these three species were 7.3, 8.8 and 9.4 grains, respectively. Pollen transfer in P . heteroclada and P . nuda depended on wind, and no flower visitors were seen in the field. However, in P . nidularia , Apis cerana Fab. was a frequent pollen collector observed from 1200 to 1330 h. The visits undertaken by thousands of honeybees resulted in a large number of pollen grains being released from the anthers in a short time (10–15 min) in one day, which accelerated and synchronized the release of pollen from the anthers that seemed to enhance the chance of pollination. Given that honeybees played an indirect role in pollen transfer this could partly explain the low p/o ratio in P . nidularia . Reviewing the literature, we found insect visits to flowers of bamboos were not infrequent phenomena. We suggest pollination efficiency should be considered as one selective factor in attempts to understand mast flowering in bamboo. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 1–7. 相似文献
2.
CHIKAKO KUDO TOMOKO SUZUKI SUMIE FUKUOKA SHUTA ASAI HIROKO SUENAGA MICHIKO SASABE YOSHITAKA TAKANO TETSURO OKUNO KAZUHIRO TOYODA TOMONORI SHIRAISHI YUKI ICHINOSE YOSHI-SHIGE INAGAKI 《Molecular Plant Pathology》2007,8(4):365-373
Non-host resistance is the most general form of disease resistance in plants because it is effective against most phytopathogens. The importance of hypersensitive responses (HRs) in non-host resistance of Nicotiana species to the oomycete Phytophthora is clear. INF1 elicitin, an elicitor obtained from the late-blight pathogen Phytophthora infestans , is sufficient to induce a typical HR in Nicotiana species. The molecular mechanisms that underlie the non-host resistance component of plant defence responses have been investigated using differential-display polymerase chain reaction (PCR) in a model HR system between INF1 elicitin and tobacco BY-2 cells. Differential-display PCR has revealed that Cdc27B is down-regulated in tobacco BY-2 cells after treatment with INF1 elicitin. Cdc27B is one of 13 essential components of the anaphase-promoting complex or cyclosome (APC/C)-type E3 ubiquitin ligase complex in yeast. This APC/C-type E3 ubiquitin ligase complex regulates G2-to-M phase transition of the cell cycle by proteolytic degradation. In this study, we investigated the roles of this gene, NbCdc27B , in plant defence responses using virus-induced gene silencing. Suppression of NbCdc27B in Nicotiana benthamiana plants induced defence responses and a gain of resistance to Colletotrichum lagenarium fungus. Elicitin-induced hypersensitive cell death (HCD) was inhibited mildly in plants silenced with tobacco rattle virus::Cdc27B. Cdc27B could manage the signalling pathways of plant defence responses as a negative regulator without HCD. 相似文献
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FUMIO FUKAI YOSHITAKA SUZUKI YOSHINORI NISHIZAWA TAKASHI KATAYAMA 《Cell biology international》1996,20(6):423-428
We previously proposed that an enzymatic cooperation between Kupffer cells and hepatocytes may play an important role in cysteinyl leukotriene (LT) production in rat liver. Anin vitrotranscellular synthesis cysteinyl LTs by a Kupffer cell—hepatocyte coculture system was characterized here. Kupffer cells alone, with A23187 stimulation, did not generate cysteinyl LTs until supplemented either with isolated hepatocytes or with LTC4synthase and glutathione, indicating that Kupffer cells can synthesize LTA4but not convert it into LTC4. In contrast, hepatocytes converted the LTA4into cysteinyl LTs and further degraded the cysteinyl LTs. Cysteinyl LT production by the Kupffer cell—hapatocyte coculture system was optimized by addition of 1–3% serum albumin to the culture and by bringing the cell—cell distance closer to less than 3μ. Tumour necrosis factor also stimulated cysteinyl LT production by the coculture system. From these results, it is expected that the Kupffer cell—hepatocyte transcellular system for cysteinyl LT production actually functionsin vivo. 相似文献
5.
YOSHITAKA NAGAHAMA GRAHAM YOUNG SHINJI ADACHI 《Development, growth & differentiation》1985,27(3):213-221
The effect of actinomycin D and cycloheximide on gonadotropin (partially purified chum salmon gonadotropin, SGA)-induced 17α, 20β-dihydroxy-4-pregnen-3-one (17α, 20β-diOHprog, a maturation-inducing steroid in amago salmon) production was examined in intact ovarian follicles and granulosa cells of postvitellogenic amago salmon, Oncorhynchus rhodurus. Both actinomycin D and cycloheximide blocked gonadotropin-induced 17α, 20β-diOHprog production by intact follicles. In contrast, gonadotropin-induced 17α-hydroxyprogesterone production by intact follicles was not abolished by actinomycin D, but was abolished by cycloheximide, suggesting that postvitellogenic amago salmon ovarian follicles already contain the RNAs necessary for the synthesis of 17α-hydroxyprogesterone. In isolated granulosa cells, chum salmon gonadotropin was able to stimulate 17α, 20β-diOHprog production only when a precursor, 17α-hydroxyprogesterone was provided in the incubation medium, indicating that gonadotropin acts directly on granulosa cells to enhance the activity of 20β-hydroxysteroid dehyrogenase (20β-HSD). Total inhibition of 20β-HSD enhancement in granulosa cells, judged by 17α, 20β-diOHprog production, was achieved when actinomycin D was added between 1 hr before the start of incubation with 17α-hydroxyprogesterone and gonadotropin to 6 hr after. With cycloheximide total inhibition was observed when added in the period of 1 hr before to 9 hr after the start of the incubation. These results suggest that chum salmon gonadotropin acts on granulosa cells to enhance the de novo synthesis of 20β-HSD by a mechanism involving RNA synthesis. 相似文献
6.
SUMMARY. 1. The winged adults of Ephoron shigae swarming over the water surface were collected by successive random sweeps during their daily emergence period, and the changes in sex and stage composition were examined, in the lower reach of the Asahi River in western Japan.
2. The emergence occurred mainly during a 11 /2 h period beginning some time after sunset. Male sub-imagos emerged synchronously and moulted to imagos in a 25 min period immediately prior to an abrupt increase of female emergence.
3. This timing of male emergence may be considered the result of selection of males to decrease the risk of death before mating, and for all the males to have an equal opportunity to mate. 相似文献
2. The emergence occurred mainly during a 1
3. This timing of male emergence may be considered the result of selection of males to decrease the risk of death before mating, and for all the males to have an equal opportunity to mate. 相似文献
7.
SHIN-ICHIRO YASUDA TAKAHIRO MIYAZAKI KOUJI MUNECHIKA MASAMI YAMASHITA YOSHITAKA IKEDA AKIHITO KAMIZONO 《Journal of receptor and signal transduction research》2013,33(4):235-246
We attempted to determine natural agonists of GPR39 in fetal bovine serum (FBS). FBS was conditioned to extract peptides and fractionated by two types of HPLC. The activity of each fraction was monitored by intracellular calcium mobilization. Then the purified active ingredient was analyzed by inductively coupled plasma mass spectrometry. In this fashion, Zn2 + ion was identified as an agonist of GPR39, though no peptidergic molecules were found. The calcium-mobilizing activity of Zn2 + was not abolished by pertussis toxin but was by a phospholipase C (PLC) inhibitor, U73122, indicating that the activity of GPR39 is mediated through the Gqα -PLC pathway. In addition, Zn2 + also activated mouse and rat GPR39, showing that the function of GPR39 as a Zn2 + receptor is conserved across species. This study is the first exploration of GPR39 agonists in FBS and indicates that GPR39 functions as a Gq-coupled Zn2 +-sensing receptor. 相似文献
8.
Decreased immune response as a proximate cost of copulation and oviposition in a damselfly 总被引:8,自引:0,他引:8
MICHAEL T. SIVAJOTHY YOSHITAKA TSUBAKI & ROWAN E. HOOPER 《Physiological Entomology》1998,23(3):274-277
Abstract.Males and females of the Japanese calopterygid damselfly, Matrona basilaris japonica Fester, showed a rapid (within 24 h), and significant reduction in immune system function (encapsulation response) after reproductive activity (copulation or oviposition).
A similar, but non‐significant, change occurred in males that conducted energetically costly behaviour (fighting).
These data suggest that there may be physiological costs other than energy‐based trade‐offs associated with copulation and oviposition that may have life‐history consequences via their effects on immune system function. 相似文献
A similar, but non‐significant, change occurred in males that conducted energetically costly behaviour (fighting).
These data suggest that there may be physiological costs other than energy‐based trade‐offs associated with copulation and oviposition that may have life‐history consequences via their effects on immune system function. 相似文献
9.
MASATOSHI MITA NOBUO UETA YOSHITAKA NAGAHAMA 《Development, growth & differentiation》1987,29(6):607-616
The effect of various disulfide-reducing agents including cysteine and its alkylesters on the induction of germinal vesicle breakdown (GVBD) in starfish ( Asterina pectinifera ) oocytes was investigated in vitro . Although cysteine did not induce GVBD, its alkylesters were effective. Cysteine alkylesters significantly mimicked the effect of 1-methyladenine (1-MeAde), the naturally occurring maturation-inducing hormone of starfish, on oocyte maturation. However, the effective concentrations and pH optimum for stimulation of oocyte maturation varied between 1-MeAde and the cysteine alkylesters. By comparing pKa values of the disulfide-reducing agents to pH of the medium, it is suggested that the redox potential of a disulfide-reducing agent is an important indicator its ability to induce oocyte maturation.
With the use of fluorescent probes for thiol groups, it was shown that the fluorescence in oocyte cortices increased within 5 min after administration of 1-MeAde. The fluorescence intensity in the cortices also increased after treatment with cysteine and its alkylesters, although the intensity was much stronger with the latter. Furthermore, both 1-MeAde and the disulfide-reducing agents were suggested to cause reduction of thiol groups within the plasma membrane as opposed to those on the external and internal surfaces. Thus, it is suggested that disulfide-reducing agents and 1-MeAde induce starfish oocyte maturation by changing the redox state of the thiol groups located within the oocyte plasma membrane. 相似文献
With the use of fluorescent probes for thiol groups, it was shown that the fluorescence in oocyte cortices increased within 5 min after administration of 1-MeAde. The fluorescence intensity in the cortices also increased after treatment with cysteine and its alkylesters, although the intensity was much stronger with the latter. Furthermore, both 1-MeAde and the disulfide-reducing agents were suggested to cause reduction of thiol groups within the plasma membrane as opposed to those on the external and internal surfaces. Thus, it is suggested that disulfide-reducing agents and 1-MeAde induce starfish oocyte maturation by changing the redox state of the thiol groups located within the oocyte plasma membrane. 相似文献
10.
Steroid Producing Cells during Ovarian Differentiation of the Tilapia, Sarotherodon niloticus 总被引:2,自引:1,他引:1
In order to examine the initial appearance and development of the steroid producing cells (SPCs) during the process of ovarian differentiation, histology and ultrastructure of tilapia ( Sarotherodon niloticus ) ovaries were investigated from 10 to 50 days after hatching. In gonads of fry at 23–26 days after hatching, initial ovarian differentiation was confirmed by the differentiation of stromal aggregations in the proximal and distal region of the gonad on the side facing the lateral wall. This represents the initial formation of the ovarian cavity. At the same time as ovarian differentiation, a few large cells appeared initially in the vicinity of blood vessels. They have some of the ultrastructural features characteristic of SPCs such as a moderate number of mitochondria with tubular cristae, a large amount of smooth endoplasmic reticulum and many free ribosomes. Based on these ultrastructural criteria, together with the present finding that these cells further differentiated into the typical SPCs at older stages, these cells were identified as SPCs. Thereafter, by 30–50 days, SPCs increased gradually in number in the area enclosing the blood vessels of ovaries. The increase in SPCs coincided with the development of germ cells, including the multiplication of oogonia and the transformation from oogonia to oocytes. 相似文献