Trifactorial interactive effects of nutrients, water potential and temperature on carbohydrate allocation to the embryonic axis of desert plant seeds     

H.M El-Sharkawi  K.A Farghali  S.A Sayed 《Journal of Arid Environments》1997,35(4):655-664

Seeds ofProsopis juliflora, Calotropis proceraandSorghum × drummondiiseeds were subjected to trifactorial treatment combinations of: nutrients (Nr), temperature (T) and reduced water potential (ψ_m) in their incubation medium. The embryonic axis and storage tissue of germinating seeds were analysed for soluble sugars (SS) and hydrolysable carbohydrates (HC). Allocation of both carbon fractions in germinating seed organs was variously affected by single factors and their mutual interactions. Differences in such effects included both magnitude and relative role of each factor or interaction, the effect also being organ and/or species dependent. The interaction φ_m× T had the predominant role in changes of both SS and HC content and their allocation in seed organs, while the interaction Nr × φ_m× T had a subdominant role. Nutrients in the medium generally induced significantly higher SS and HC content in whole seeds at low water potentials, the level of which is temperature dependent (indicating interactive effects between single factors). Also, nutrients generally increased translocation of SS to the radicle (hence, allocation of HC), improving its capacity of water uptake through increased osmolarity.  相似文献   

胶质芽孢杆菌的胞外分泌物与细菌的解钾作用   总被引：4，自引：0，他引：4  

杜叶  周雪莹  连宾 《地学前缘》2008,15(6):107

研究了胶质芽孢杆菌(Bacillus mucilaginosus)KO1菌株在不同培养条件下,其荚膜多糖含量随时间的变化以及菌株在有氮、无氮培养基中的解钾作用。结果表明,尽管该菌在无氮培养条件下的菌体数量远小于有氮培养条件,但无氮培养条件下所提取的细菌多糖多于在有氮条件下培养所提取的细菌多糖;胶质芽孢杆菌在以添加钾长石粉或黑云母粉制作的无氮培养基中生长可形成大量多糖,采用丙酮法进行细菌培养液多糖提取,发现细菌培养的第3天所提多糖含量最高;胶质芽孢杆菌在以添加钾长石粉或黑云母粉制作的有氮培养基中生长亦可形成较多的多糖,且在细菌培养的第4天所提多糖含量最高;胶质芽孢杆菌在有氮条件下对含钾矿物的释钾率高于在无氮条件下的释钾率,这可能与该菌在有氮条件下生长更快、可产生较多菌体细胞有关。分析表明,该菌在有氮条件下产生的胞外糖蛋白高于在无氮条件下产生的胞外糖蛋白,蛋白质在细菌分解转化含钾矿物过程中可能发挥重要作用。  相似文献   

Distinguishing between cellular and Fe-oxide-associated trace elements in phytoplankton     

Degui Tang  François M.M. Morel 《Marine Chemistry》2006

In cultures and in nature, ferric (oxyhydro-)oxides (FeO_x) precipitate and become associated with phytoplankton surfaces. Other trace elements adsorb on FeO_x and it is thus difficult to differentiate between cellular- and oxide-associated concentrations of both iron and these elements. Existing techniques to selectively dissolve the FeO_x associated with phytoplankton surfaces often contaminate the sample or necessitate elaborate pre-cleaning procedures and/or proceed by unknown and thus uncontrolled mechanisms.  相似文献   

象山港海域中石油烃含量分布特征及其评价   总被引：3，自引：0，他引：3  

卢冰  熊健 《海洋学研究》1993,11(4):67-74

本文分析了象山港海域石油烃含量的分布规律,并对海域遭受污染程度进行了评价,该海域的石油含量在0.01～0.45mg/dm~3之间,平均值为0.072mg/dm~3,比一类海水标准浓度值高0.44倍,油污染平均指数Ai值为1.5,表明该海域已有相当程度的油沾污。  相似文献   

大亚湾水体中溶解的碳水化合物     

张穗  方正信 《热带海洋学报》1991,(4)

根据1985年10月至1986年8月对大亚湾进行的环境调查,本文报道海水中溶解的碳水化合物(DCHO)的调查结果,讨论了该海区DCHO的分布特征及季节性变化。对DCHO和叶绿素a、磷酸盐、溶解氧、颗粒有机碳、温度以及盐度之间进行了相关分析,综合探讨了影响D-CHO含量变化的因素。结果表明,浮游植物在大亚湾水体中DCHO的浓度调节方面起着主要的作用。  相似文献   

应用Cornell方法对重口裂腹鱼[Schizothorax (Racoma)davidi]幼鱼适宜常量营养物质需求量研究     

宁毅  冯健  何姝珍  孙晓峰  陈斌 《海洋与湖沼》2012,43(4):748-755

采用Cornell方法研究了初始重为(2.0±0.1)g的重口裂腹鱼幼鱼日粮中常量营养物质的适宜需求量。日粮中蛋白质、脂肪和碳水化合物梯度变化范围分别为33%—51%、3%—18%和24%—33%,试验周期为60d。试验结果表明,除日粮蛋白质33%组鱼成活率明显下降外(P<0.05),其它试验日粮中3种常量营养物质含量对重口裂腹鱼幼鱼成活率没有显著影响(P>0.05)。当日粮蛋白质水平≤45%时,其特定生长率随着日粮蛋白质水平上升而明显增加;当日粮蛋白质水平在33%—36%时,重口裂腹鱼的特定生长率显著降低(P<0.05)。除12%日粮脂肪组试验鱼外,9%日粮脂肪组试验鱼的特定生长率显著性高于其它脂肪水平日粮组(P<0.05),但当日粮中脂肪含量≥15%后,重口裂腹鱼鱼体脂肪含量显著上升(P<0.05),肝细胞脂肪变性明显。日粮中不同的碳水化合物水平对重口裂腹鱼特定生长率没有显著影响(P>0.05),但当日粮中碳水化合物为33%时,鱼体糖原含量显著增加(P<0.05)。试验表明,重口裂腹鱼幼鱼日粮蛋白质、脂肪和碳水化合物3种常量营养物质的适宜需求量分别为45%、9%和≤30%。日粮总能为19.0MJ/kg,蛋白质能量比(P/E)为23mg/J。  相似文献   

低温和赤霉素对百合鳞茎休眠解除的影响     

金鑫  李彬  牛丽涓  王萌  朱永超  徐晴晴  肖洪浪  廖伟彪 《中国沙漠》2016,36(5):1315-1322

以百合品种“西伯利亚”为材料,研究了低温和赤霉素（GA₃）处理对百合鳞茎休眠解除过程中形态和碳水化合物含量的影响,以及不同温度条件下鳞茎不同部位内源GA₃含量的变化。结果表明：低温（5℃）和0.15 g·L^-1 GA₃处理35 d时芽长与鳞茎高比值为67.954%,芽生长点位于鳞茎直立高度约2/3处,解除休眠所需天数最少;鳞茎在0~14 d时淀粉降解最快,第35天时可溶性总糖和还原糖含量最高。低温处理的内层鳞片和芽内源GA₃含量变化显著,且温度越低,变化越明显。低温条件下内层鳞片和芽的内源GA₃含量较高,上升趋势最为明显;而外层鳞片和根的GA₃含量水平较低,变化趋势较小。可见,顶芽和内层鳞片可能为整个鳞茎休眠解除活动的中心。  相似文献   

Carbohydrate and nutrient content in rhizomes of Phragmites australis from different habitats of Lake FertÕ/Neusiedlersee     

Mria Dinka  Pter Szeglet 《Limnologica》1999,29(1):47-59

Changes in the soluble sugar, starch, total non-structural carbohydrate (TNC) and nutrient (N, P, K) concentration in the reed rhizome were investigated in different reed habitat types in Lake Fertõ/Neusiedlersee during the vegetation period in 1993 to 94. Three die-back and four vigorous reed stands were monitored.For biomass estimations rhizomes were collected twice, in early summer and in autumn. They were calculated to be 1.9 to 2.7 kg/m² at die-back and 3.1 to 6.1 kg/m² at vigorous sites.The carbohydrate and nutrient concentrations of the reed rhizomes were high at the beginning of the vegetation period; they reached their minima in May–June, which was followed by a gradual increase until the end of the vegetation period. From autumn to spring the concentrations decreased, e.g. TNC concentration by 15 to 40% at vigorous, 50 to 70% at die-back sites.In both years the lowest carbohydrate concentrations were recorded at the end of May, a month before the inflorescence developed (vigorous sites: 50–70 mg TNC/g, die-back sites: 70–120 mg TNC/g). In that period the standing stock of the TNC in the rhizome did not separate the sites clearly, and the smallest carbohydrate standing stock was measured at a vigorous site with a high water cover.At the beginning of summer and in autumn the soluble sugar, TNC and N concentration values were higher at the die-back than at the vigorous sites but the standing stock was higher at the vigorous sites. In autumn the TNC standing stock of the rhizomes was between 780 and 1200 g/m² at vigorous, between 380 and 690 g/m² at die-back sites. This is especially important for the reactions and resistance of die-back reed stands to unfavourable conditions.  相似文献   

斑节对虾病原菌胞外产物的致病性研究   总被引：16，自引：0，他引：16  

张朝霞  王军  苏永全  幺久刚  周胜利  鄢庆枇 《海洋学报》2000,22(5):94-99

由养殖濒死病虾体内分离的副溶血弧菌(2019#)、溶藻弧菌(4302#)和嗜水气单胞菌(1003#)培养液中分别提取了胞外产物,测定了酶成分,定量分析了蛋白酶及磷酸酯酶的活性.用细菌胞外产物粗提液对斑节对虾进行致死试验,戊二醛固定致死对虾的肝组织,电镜观察了斑节对虾肝组织的超微病变,初步探讨了三株细菌胞外产物诱发虾病的病理.  相似文献   

Coral reef productivity and diversity—Contributions from enhanced photosynthesis via demand for carbohydrate from the host     

Melanie S. Adams  Barbara Demmig-Adams  Ruiqi Li  Daniel Zarate  Jingchun Li 《Marine Ecology》2020,41(6):e12618

Coral reefs’ high productivity has been attributed mainly to photosymbioses between the coral animal and algae of the family Symbiodiniaceae, with recognition that the host can increase algal photosynthesis by concentrating nutrients and enhancing the efficiency of light absorption. Here, we propose that an additional effect, consumption of carbohydrate by the host, may also enhance algal photosynthesis. We examine evidence from symbiosis between terrestrial plants and root fungi that indicates a link between carbohydrate consumption by the symbiotic partner and photosynthetic upregulation in the plant system. In addition, we review evidence from free-living algae manipulated to exude carbohydrate into the external medium, which was associated with strong upregulation of photosynthetic capacity. We offer suggestions on how host-induced carbohydrate release may increase photosynthesis rates in the symbionts in the intact photosymbiosis and how this relationship evolved.  相似文献