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971.
分析了华贵栉孔扇贝Chlamysnobilis(Reeve)、合浦珠母贝Pinctadamatensii(Duuker)、翡翠贻贝Pernavirldis(Linnaeus)的软体部、肝胰腺和生殖腺的脂肪酸组成及含量。3种贝的各组织中,不饱和脂肪酸含量均较饱和脂肪酸含量高。多不饱和脂肪酸(PUFA)含量丰富,其中二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)含量相当高,占总脂肪的25.26%-27.21%。3种贝中,翡翠贻贝的油含量最高(13.68%),软体部的EPA和DHA含量也较高(26.95%),最具开发利用价值。 相似文献
972.
中国对虾(Penaeus chinensis)的白点综合征病毒(WSSV)的提纯和核酸提取 总被引:1,自引:1,他引:0
作者从发生白点综合征的中国对虾中,提取了一株白点综合征病毒,用电镜对纯化的病毒进行了形态学观察,并对病毒纯化过程中蛋白酶抑制剂的使用及离心速度的选择进行了探讨。经蔗糖密度梯度离心,分取各带负染后电镜观察,病毒条带位于40%~50%蔗糖梯度之间,其完整毒粒长225~270nm,直径75~88nm,有的完整毒粒带有很长的尾,病毒衣壳长250~320nm,直径60~80nm。在匀浆使用的缓冲液中加入蛋白酶抑制剂PMSF,可得到完整的带包膜的病毒颗粒,比不使用PMSF的提纯效果要好。经3000r/min离心5min,5000r/min离心25min,去除大部分的组织碎片,经10000r/min离心1h,可使大部分病毒沉淀。并采用传统的方法对病毒核酸进行了提取,其基因组经初步分析为dsDNA。 相似文献
973.
13C uptake experiments were carried out at a station off the west coast of Hokkaido Island, Japan, during the period between late winter and spring bloom in 1997. The composition of newly biosynthesized particulate fatty acids was determined using a 13C tracer and gas chromatography/mass spectrometry (13C GC/MS), and compared with that of particulate matter (seston). Two fatty acid compositional ratios revealed that diatoms biomass (16:1(n−7)/16:0, ∑C16/∑C18) were strikingly high in new cells compared with seston on 17 April, coinciding with the dominance of fucoxanthin. In this study, the Polyunsaturation Index (a measure of the percentage of C16 fatty acids that are polyunsaturated) in new cells is generally close to that in seston, while there was a notable discrepancy between new cells and seston in surface (10 m) waters on 17 April. This large difference between new cells and seston is ascribed to: (1) an increase of newly synthesized storage lipids (mainly 16:0 and 16:1) induced by nitrogen limitation in the top 10 m of the water column; (2) an addition of earlier synthesized phytoplankton cells (high Polyunsaturation Index at logarithmic growth stage) and non-phytoplankton components (detritus and bacteria and zooplankton) into seston. The highest Polyunsaturation Index of C16 fatty acids in seston (33%) occurred at 100 m water depth. This may be caused by “settling planktonic aggregates” or “diatom resting spores”. In the present study, it is reasonable to suggest that the Polyunsaturation Index of C16 fatty acids can be a useful indicator for the ecophysiological state of marine diatom populations. 相似文献
974.
975.
976.
Abundance, Sources and Speciation of Trace Elements in Humus-Rich Streams Affected by Acid Sulphate Soils 总被引:3,自引:0,他引:3
The behaviour of trace elements (Al, As, Cd, Co, Cr,Cu, Fe, Mn, Ni, V, Zn) was studied in five humus-richstreams (dissolved organic carbon = 14–40 mg/L)impacted by acid sulphate soils developed in marinesulphide-bearing fine-grained sediments. During heavyrainfalls in autumn, on which the study focusses, themetals Al, Cd, Co, Cu, Mn, Ni and Zn are extensivelyleached from these acidic soils (pH = 2.5–4.5), whileAs, Cr, Fe and V are not leached more strongly fromthis soil type than from areas of till and peat. Aspeciation experiment, based on anion and cationexchange of the stream waters in the field, showedthat (1) the metals Al, Cd, Co, Mn, Ni and Zn aretransported in the streams mainly as inorganiccations, (2) Cu exists mainly in cationic form but isalso to a significant extent associated with dissolvedhumic substances, (3) Fe occurs mainly in the anionicfraction explained by organic coating on colloidal Feoxyhydoxides and (4) the hydrochemistry of As, Cr andV is complex as these elements may exist in severalunquantified anionic fractions and to a minor extentin cationic species/forms. Whereas the proportion ofacid sulphate soils in the catchments had a largeimpact on concentrations levels of several elements inthe stream waters, these soils did not have a largeaffect on the speciation of elements in water. 相似文献
977.
978.
M. A. A. Gadallah 《Journal of Arid Environments》2000,44(4):451
Three-week old soybean (Glycine max) plants were subjected to a factorial combination of four regimes of soil matric water potential (ψm=−0·03, −0·5, −1·0 and −1·5 MPa), two levels of supplementary Zn (O and 20 mgl−1) and two levels of foliar IAA application (O and 10 mgl−1). Under control conditions (no Zn, no IAA), increasing soil drying progressively retarded shoot and root growth (length and dry mass production), reduced leaf relative water content (RWC) and decreased the contents of chlorophyll (Chl) and shoot soluble sugars (SS), but increased soluble sugar content of roots and lowered osmotic water potential of shoots and roots (osmotic adjustment). Total free amino acid (TAA) content increased in shoots but decreased in roots whereas contents of soluble proteins (SP) decreased in shoots and roots. The effect of water stress was statistically significant (p<0·05) and had a major effect (as indicated by η2values) on leaf RWC, shoot and root dry masses and osmotic potential. Supplementary Zn improved root growth at all levels of stress and shoot growth under severe stress. Improvement of growth was positively correlated with the internal tissue Zn concentrations (r=0·91 and 0·86 for shoot and 0·94 and 0·82 for root length and dry mass respectively). Exogenous IAA raised (p<0·05) RWC, Chl, DM (slightly), root SS, and SP, whereas shoot TAA was lowered. Effects on root TAA and shoot SS were more complex: they were lowered at zero stress and raised under severe stress. IAA and Zn in combination had additive effects on Chl, growth and osmotic potential, but their combined effects on SP and TAA were more complex. It is concluded that the treatment of soybean plants grown under conditions of low soil water potentials and Zn deficiency with Zn and IAA solutions counteracted the deleterious effects of stress, especially at high stress levels, and helped stressed plants to grow successfully under these adverse unfavourable conditions. 相似文献
979.
LIU Sumei ZHAO Yingfei REN Jingling ZHANG Jing SUN San JIN Jie ZHANG Guiling 《海洋学报(英文版)》2010,29(1):42-51
Phosphorus (P) is an essential nutrient utilized by all organisms for energy transport and growth.
Both the conventional molybdenum-blue method and the magnesium-induced coprecipitation
(MAGIC) procedures were applied for the measurement of dissolved inorganic phosphorus (DIP)
and total dissolved phosphorus (TDP) in more than 840 water samples collected between 2003 and
2005, including seawater (the Huanghai Sea, the East China Sea, and the northern South China
Sea), water from rivers and estuaries (the Changjiang, the Huanghe, and the major rivers emptying
into the Jiaozhou Bay), groundwater (in the drainage basin surrounding the Jiaozhou Bay), rain-
water, and aquaculture water samples. The MAGIC method allows the investigation of phosphorus
distributions and cycling for systems in which DIP is below the detection limits of conventional
methods. Comparison between the two methods demonstrated that the concentrations obtained
with both methods were signiˉcantly correlated. The di?erences of DIP and TDP concentrations
measured with the two methods were higher when the concentrations of DIP and TDP were lower,
implying the lower reproducibility at low concentrations. The concentration di?erences increase
with the increase in the proportion of DOP in TDP, which indicates that the discrepancy of DIP
concentrations measured with the two methods increases when the DOP concentration is high. The
discrepancies indicated that the composition of P compounds di?ers depending on sample sources
and water type; it would be useful to infer the presence of di?erent phosphorus compound pools
from di?erences between the two methods. This study indicates the potential presence of a pool
of alkaline-labile compounds for samples from rainwater and rivers and estuaries surrounding the
Jiaozhou Bay; the potential presence of acid-labile compounds that were adsorbed by Mg(OH)2 for
samples from the Changjiang Estuary, Huanghai Sea, East China Sea, and groundwater; the po-
tential presence of a substantial pool of acid-labile compounds that were not adsorbed by Mg(OH)2
for samples from the Huanghe Estuary, aquaculture water, the East China Sea algal bloom water,
and the northern South China Sea. 相似文献
980.