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集约高产过程中土壤有机质动态初探 总被引:2,自引:0,他引:2
集约高产过程中土壤有机质动态初探崔玉亭,韩纯儒(北京农业大学,100094)DynamicsofSoilOrganicMatter(SOM)intheProcessofAgriculturalIntensification¥.CuiYuting;HanChunru(BeijingAgriculturalUniversity,100094).ChineseJournalofEcology,1993,12(2):37—38.Inthispaper,thebalanceofsoilorganicmatter(SOM)intheprocessofagriculturalintensificationinChangzhouregionisstudiedandamedium-andlong-termpredictionofitsdynamicsismade。There-sultsshowthatduringthisprocess,thebalanceofSOMisgettingbetter,andafteramediumorlongpe-riod(e.g,10—20yeats),theSOMcontentcangett 相似文献
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鲁西北平原高产夏玉米生育模式董振国,鲁全国(中国科学院地理研究所,北京100101)DevelopmentMOdelofHighYieldingSummerCornonNortbwestSkandongPlain¥DongZhenguo;LuQuanguo(InstituteofGeography,ChineseAcademyofSciences,Beijing100101),ChineseJournalofE-colegy,1993,12(2):69-72.Erectandplanevarietiesofcornhavealeafinclinationof65°and50°andtheiroptimumplantingdensitiesare75000-82000and52500-60000stems·ha ̄(-1).Theleafareaindexatearsproutingstageandleafareaday(LAD)fortheformerarerespectively5.5-6.0and360-400,whilethoseforthelatterare3.5-4.0and260-300.TheL 相似文献
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太岳山丘陵地带中国林蛙成体的肥满度和某些器官系数的季节变化 总被引:8,自引:0,他引:8
太岳山丘陵地带中国林蛙成体的肥满度和某些器官系数的季节变化卢欣(山西省生物研究所,太原030006)SeasonalVariationsofAdult’sCorpulenceDegreeandOthcrOrgans’IndicesofCommonFrogsinTaiyucMountainIIillyLands¥.LuXin(ShanxiInstituteofBiology,Taiyuan030006).ChineseJournalofEcolo-gy,1993,12(4):33-35.InvestigationswerecarriedoutfrornFebruary1989toApril1990inTaiyuemountainofShanxiprovince.Theadult'scorpulencedegreeofcommonfrogsishigherduringhibernationaidlowestinMayandJune,andthatofmalesissignlficantlyhigherthanfemales’(exceptinAugust).DuringApril-August,thecoef- 相似文献
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鼎湖山土壤的微生物及其对酸度的适应特征 总被引:2,自引:0,他引:2
鼎湖山土壤的微生物及其对酸度的适应特征葛荣盛(广东省土壤研究所广州510650)SoilMicrobcsatDinghushanNaturalReserveandTheirAdaptabilitytoAcidity¥.GeRongsheng(Guang-dongInstituteofSoilSciences,Guangzhou510650).ChineseJournalofEcology,1993,12(3):11-18.ThispaperdiscussesthemicrofloraeinsoilsunderdifferentforesttypesatDinghusannaturalreserveandtheiradaptabilitytoacidity:1.Undermixedforest,ammonifyingBacteria,cellulose-decomposingbacteriaandOligonitrophilesaredominant;underbroadleavedforest,ceIlulose-decomposingfungiaremore;andlittledifferencecanb 相似文献
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莱氏衣原体膜上Mg~(2+)-ATPase用DOC溶解后,经Sepharose-6B和DEAE-CelluloseDE-52离子交换柱,得到了部分纯化的Mg~(2+)ATPase,并将此ATPase与不同极性头部的磷脂和膜糖脂重组,研究了不同的极性头部的磷脂和膜糖脂对ATPase活性的影响。此酶的活性不依赖酸性磷脂,PG、DPG、大豆磷脂等明显抑制酶活性,中性磷脂DMPC、PE、PC则能增加酶活性,其中尤以非双层脂PE的作用最为明显。从莱氏衣原体膜上提取的糖脂(MGDG,DGDG)单独和ATPase重组时,酶活性增加并不明显,当MGDG和DGDG以等比例混合时,能大大地增加酶活性。这表明Mg~(2+)-ATPase的活性很大程度上与磷脂的表面电荷及磷脂的组成相关。 相似文献
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Metylomonassp.GYJ3菌的甲烷单加氧酶(MMO)粗酶提取液经DEAE-SepharoseCL-6B阴离子交换层析、SephadexG-100凝胶过滤层析和DEAE-TSKgelHPLC分离纯化出MMO还原酶组分.经HPLC分析,纯度大于95%,纯化倍数为4.4,加入至MMO羟基化酶和调节蛋白B的体系中表现比活为228nmol环氧丙烷每分钟毫克蛋白.SDS-PAGE电泳表明还原酶由一种亚基组成,分子量42kD.ICP-AES测定还原酶的Fe含量为1.83molFe每mol蛋白.UV-Vis光谱表明还原酶除280nm蛋白质特征峰外在460nm有最大吸收峰,且A280nm/A460nm为2.50,与其它黄素一铁硫蛋白相似,推测还原酶可能含一个FAD辅基和Fe2S2中心.在厌氧条件下,还原酶能够和NADH作用,UV-Vis光谱分析表明还原酶460nm处特征吸收峰消失,说明在MMO催化过程中还原酶接受NADH的电子.DEAE-SepharoseCL-6B阴离子交换层析分离出调节蛋白B,部分纯化的调节蛋白B的分子量大约在20kD,它能够提高MMO比活性40倍,MMO还原酶和调节蛋白B单独存在时不具有MMO 相似文献
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X. C. ZHANG 《植物研究》1998,18(1):107-117
GENUSANTROPHYUMKAULF.FROMCHINAANDNEIGHBORINGREGIONSX.C.ZHANG(Theherbarium(PE),InstituteofBotany,ChineseAcademyofSciences,Bei... 相似文献
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6-Dimethylaminopurine (6-DMAP), a reversible inhibitor of the transition to metaphase during the first meiotic cell division of the mouse oocyte 总被引:6,自引:0,他引:6
The first meiotic cell division (meiotic maturation) of dictyate stage mouse oocytes removed from the follicle resumes spontaneously in vitro. We used the puromycin analog 6-dimethylaminopurine (6-DMAP) to test the respective roles of protein synthesis and protein phosphorylation in driving this process. While protein synthesis inhibitors do not block meiosis resumption, 6-DMAP was found to inhibit germinal vesicle breakdown (GVBD), by inhibiting the burst of protein phosphorylation without changing the rate of incorporation of [35S]methionine into proteins. This effect is reversible; it depends both upon drug concentration and the particular female. When added after GVBD and before the emission of the first polar body, 6-DMAP decreases the level of protein phosphorylation and induces decondensation of the chromosomes and reformation of the nuclear envelope. In contrast, 6-DMAP did not trigger these processes in metaphase II oocytes which only produce resting nuclei when treated by protein synthesis inhibitors. From these data, we conclude that (1) the early appearance and stability of mouse MPF in Metaphase I oocytes depend on protein phosphorylation rather than on protein synthesis, and (2) protein synthesis is necessary to maintain the condensation of the chromosomes in metaphase II oocytes. 相似文献
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The effect of 6-dimethylaminopurine (6-DMAP) on germinal vesicle breakdown (GVBD) and maturation in bovine oocytes was investigated in this study. This puromycin analog has been shown to be an inhibitor of phosphorylation. Whereas GVBD occurred in nearly all oocytes (96.8%, 120/124) in control medium, presence of 6-DMAP (2 mM) blocked this process almost completely, irrespective of the presence (98.3% GV, 349/355) or absence (97.1% GV, 165/170) of cumulus cells. When lower concentrations of 6-DMAP were used (100-500 microM), GVBD was observed in 87.9% of oocytes, but their maturation was arrested at late diakinesis-metaphase I stage. The inhibition of GVBD was fully reversible, but most of the metaphase II plates were abnormal (80%). To assess whether the action of 6-DMAP is different from the inhibitors of protein synthesis, metaphase II oocytes were exposed to either cycloheximide or 6-DMAP, respectively. Whereas in cycloheximide-supplemented medium approximately 80% of the oocytes were activated, parthenogenetic activation was much less frequent after incubation in 6-DMAP (14.5%). Fusion studies showed that, even if GVBD occurs in 6-DMAP supplemented medium, the level of the maturation-promoting factor (MPF) is decreased. These experiments may indicate the importance of phosphorylation for GVBD in cattle oocytes. 相似文献
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Protein phosphorylation patterns were studied by radiolabelling goat cumulus oocyte complexes with [32P]orthophosphate for various periods of time. The radiolabelled denuded oocytes were assessed for nuclear status and were used individually for gel electrophoresis. This study demonstrated that specific changes in protein phosphorylations were programmed during goat oocyte maturation. One of the most prominent changes was a general increase in the phosphorylation rate at germinal vesicle breakdown (GVBD). From 8 hr of culture, dominant phosphoprotein bands with apparent molecular weights of 27, 31, 40, and 50 kD were observed; they remained at this level until the metaphase II stage. In the molecular weight range of 65–80 kD, the protein phosphorylation pattern exhibited characteristic differences, with a complex series of phosphoproteins appearing and disappearing, during maturation. Addition of 6-dimethylaminopurine (6-DMAP) at the onset of culture blocked the maturation process after GVBD and induced a dramatic condensation of chromatin. When added at different times after GVBD, 6-DMAP invariably induced chromosome condensation. This inhibition was partly reversible; i.e., after removal of the drug, oocytes were able to progress only until metaphase l. © 1993 Wiley-Liss, Inc. 相似文献
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6—DMAP对小鼠卵母细胞减数分裂启动及孤雌发育作用 总被引:3,自引:0,他引:3
小鼠卵泡卵母细胞体外培养过程中加入2mmol/L6-DMAP可抑制卵母细胞自发的染色持浓缩和生发泡破裂(GVBD)。源自超排的MⅡ期卵母细胞则能为6-DMAP所激活。hCG注射后18-19h的卵母细胞置于2mmol/L6-DMAP的CZB溶液中培养0.5h、1h、2h、3h,卵母细胞的激活率分别为26.1%、75.2%、75.8%、77.3%、卵裂率分别为88.2%、73.2%、67.0%、58. 相似文献
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In Xenopus oocytes, metaphase II arrest is due to a cytostatic factor (CSF) that involves c-Mos, maintaining a high MPF (cdk1/cyclin B) activity in the cell. At fertilization, a rise in intracellular calcium triggers the proteolysis of both cyclin B and c-Mos. The kinase inhibitor 6-dimethylaminopurine (6-DMAP) is also able to release matured Xenopus oocytes from metaphase II block. This is characterized by c-Mos proteolysis without degradation of cyclin B. We hypothesized that 6-DMAP induced an increase in intracellular calcium. Using the calcium-sensitive fluorescent dye Fura-2, we observed a systematic increase in intracellular calcium following 6-DMAP application. In matured oocytes previously microinjected with the calcium chelator BAPTA, no calcium changes occurred after 6-DMAP addition; however, c-Mos was still proteolysed. In oocytes at the GVBD stage, c-Mos proteolysis occurred in response to 6-DMAP but not to calcium ionophore treatment. We suggest that c-Mos proteolysis is rather controlled by a phosphorylation-dependent process. 相似文献
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Germinal vesicle breakdown (GVBD) in cumulus-enclosed and denuded cattle oocytes was sensitive to puromycin at concentrations at or above 50 micrograms/ml. Media supplemented with 5-25 micrograms/ml of puromycin did not significantly reduce either rate or sequence of GVBD after 8 h of culture (82-96% GVBD). In concentrations of 50, 75, and 100 micrograms/ml, GVBD occurred in 15, 4, and 2% of oocytes, respectively. However, 50 micrograms puromycin/ml did postpone the time sequence of GVBD, since all treated oocytes underwent GVBD after 20 h of culture. Oocytes arrested in the germinal vesicle (GV) stage possessed GV filled with highly condensed bivalents. The puromycin block (100 micrograms/ml) was fully reversible, and the time sequence of GVBD was two times faster than in control medium. Proteins important for GVBD were synthesized during the first 4 h of culture, and 81% of oocytes underwent GVBD when puromycin (100 micrograms/ml) was added after 4 h of preincubation in control medium. The first polar body (I PB) expulsion was more sensitive to inhibition of protein synthesis, as shown by the observation that 2.5 and 5 micrograms puromycin/ml significantly (69 and 61%) reduced the incidence of Metaphase II, and 10 micrograms/ml highly significantly (31%) reduced it. The I PB expulsion in concentrations of 25 and 37 micrograms puromycin/ml was less than 5%. The subsequent culture in puromycin (8 h) and 6-dimethylaminopurine (8 h) proved that nuclear membrane breakdown is less sensitive to inhibition of protein phosphorylation than the process of chromatin condensation. 相似文献
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6-Dimethylaminopurine blocks starfish oocyte maturation by inhibiting a relevant protein kinase activity 总被引:15,自引:0,他引:15
The puromycin analog N6,N6-dimethyladenine (6-dimethylaminopurine or 6-DMAP) was found to inhibit meiosis reinitiation in starfish oocytes stimulated by the natural hormone 1-methyladenine. Increasing concentrations of this agent delayed and eventually blocked germinal vesicle breakdown. They were found to be effective even when applied during the hormone-independent period, after the oocytes had been already committed to reinitiate meiosis. 6-DMAP mimics most of the effects of emetine since it induces protein dephosphorylation, inhibits polar body formation, and promotes the precocious appearance of resting nuclei. However, unlike emetine, 6-DMAP does not affect protein synthesis. The effect of this agent cannot be accounted for by a stimulation of the protease or phosphoprotein phosphatase activities since the rate and extent of protein dephosphorylation do not increase in its presence. Data from in vivo and in vitro endogenous protein phosphorylation experiments suggest rather that 6-DMAP may directly or indirectly affect the activity of a relevant c-AMP and Ca2+-independent protein kinase which is stimulated after hormone addition and seems to support starfish oocyte maturation. 相似文献
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In prophase I-arrested surf clam oocytes, fertilization is the normal trigger for resumption of meiosis, first evidenced by germinal vesicle breakdown (GVBD). Various artificial agents are able to induce GVBD and most of them require the presence of external Ca2+ to be efficient. One exception to this rule is the reported possibility of inducing GVBD by an hypertonic treatment, using high concentrations of glycerol, in the complete absence of external Ca2+. We have investigated the processes underling glycerol-induced activation and found that, under this condition, GVBD shows very slow kinetics and is not followed by any normal subsequent steps of meiosis, such as formation of metaphase chromosomes or polar body extrusion. Glycerol-activated oocytes do not show the normal response in protein synthesis but they undergo increased protein phosphorylation which is inhibited by 6-dimethylaminopurine (6-DMAP), which also inhibits GVBD. We conclude that the hypertonic treatment by glycerol, in the complete absence of external Ca2+, induces a partial program of activation through increased protein phosphorylation but that the normal full response requires an increased Ca2+ influx as triggered by other well-known artificial activating agents. 相似文献
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The objective of this study was to investigate the possible effect of demecolcine, a microtubule-disrupting reagent, on induced enucleation (IE) of sheep meiotically maturing oocytes. Immunofluorescent staining with anti-tubulin antibodies was used to examine the spindle status of the oocytes. When the oocytes with intact germinal vesicles (GV) were cultured in the medium containing various concentrations of demecolcine (0.01 to 0.4 microg.mL-1) for 20 to 22 h, the spindle microtubule organization and first polar body (PB1) extrusion were inhibited by demecolcine in a dose-dependent manner. The highest IE rate (58.1%) was from the treatment with 0.04 microg.mL-1 demecolcine. Demecolcine treatment applied after germinal vesicle breakdown (GVBD) or at metaphase (M) yielded a PB1 extrusion rate and IE efficiency similar to the treatment applied at the onset of maturation. Analysis by immunofluorescence showed that both nonspindle microtubules and spindle microtubules were significantly disorganized by demecolcine. Combination treatment with demecolcine and cycloheximide (CHX) or 6-dimethylaminopurine (6-DMAP) led to single pronuclear formation rather than PB1 extrusion. When demecolcine-treated oocytes were transferred into demecolcine-free medium, the ability to extrude PB1 was quickly restored and a 72.1% IE rate was obtained following such treatment. These results demonstrate that demecolcine can be used as a potential reagent for induced enucleation of sheep meiotically maturing oocytes and may greatly facilitate research in nuclear transfer. 相似文献
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Chromatin behaviour under influence of puromycin and 6-DMAP at different stages of mouse oocyte maturation 总被引:5,自引:0,他引:5
Maria S. Szöllösi Pascale Debey Daniel Szöllösi Hélène Rime Dominique Vautier 《Chromosoma》1991,100(5):339-354
Preovulatory mouse oocytes were cultured in vitro up to each subsequent stages of maturation: germinal vesicle (GV), germinal vesicle breakdown (GVBD), groups of not yet individualized bivalents, circular bivalents, late prometaphase I, metaphase I, anaphase I and telophase I. The stages were identified in living oocytes by fluorescence microscopy using Hoechst 33342 as a specific vital dye. Oocytes from each stage of development developed in vitro and ovulated metaphase II oocytes were subsequently cultured in the presence of puromycin or 6-dimethylaminopurine (6-DMAP), an inhibitor of protein phosphorylation. The effects on chromatin of these drugs were studied during and at the end of culture by fluorescence and electron microscopy. We found that puromycin and 6-DMAP stop meiosis when applied at all stages of oocyte maturation, except for metaphase II. Oocytes at this stage are activated by puromycin. Reaction of the oocytes to the two drugs is different at GV and at metaphase II. All of the other stages react to the drugs by chromatin compaction, which can be followed by chromatin decondensation to form a nucleus. Our results suggest that late prophase chromatin condensation, bivalent individualization and retention of their individuality, as well as individualization of monovalents from telophase and retention of their individuality at metaphase II, are dependent on protein phosphorylation. The events occurring between metaphase I and telophase I are independent of protein synthesis and phosphorylation. The events occurring between metaphase II and formation of the nucleus are independent of protein synthesis.by U. Scheer 相似文献