Adaptability of water-plant cultivated in different mediums     

DING Hua-qiao  LI Fang  CHEN Tian-tian  CHANG Le  WU Tie-ming 《湖南农业大学学报(自然科学版)》2008,34(6)

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Changes in fatty acid and sterol composition during oogenesis in the pearl oyster Pinctada margaritifera     

Isabelle Vahirua‐Lechat  Frédéric Laure  Jean René LeCoz  Jean Pierre Bianchini  Mereani Bellais  Gilles Le Moullac 《Aquaculture Research》2008,39(16):1739-1746

The fatty acid and sterol composition of the oyster Pinctada margaritifera during oogenesis and in eggs was analysed. No major differences were observed during oogenesis, but the egg composition was significantly different from that of gonads. The amount of saturated fatty acids was the highest in eggs and the C16:0 predominant (P<5%); by contrast, the amount of 22:6(n‐3) was significantly lower (P<5%) than in gonads. No major differences were observed for the polar lipid (PL) composition during oogenesis. The main free sterols in gonads and eggs were cholesterol and brassicasterol. Among free sterols, the proportion of cholesterol diminished continuously from the beginning to the end of gonad maturation, and this decrease persisted in eggs after spawning. Cholesterol represented 40% to 55% of the sterol ester encountered in gonad and eggs. This study allowed us to investigate the fatty acid and sterol composition during oogenesis of the pearl oyster P. margaritifera, leading to a clearer understanding of the nutritional requirements of pearl oyster during the reproduction process.  相似文献   

Effects of dietary highly unsaturated fatty acids and astaxanthin on the fecundity and lipid content of pond-reared Penaeus monodon (Fabricius) broodstock     

Jian-Hua Huang  Shi-Gui Jiang  Hei-Zhao Lin  Fa-Lin Zhou  & Le Ye 《Aquaculture Research》2008,39(3):240-251

Five diets that contained fresh squid meat as the basic constituent and were supplemented with different amounts of highly unsaturated fatty acids (HUFA) and astaxanthin were fed to pond‐reared Penaeus monodon broodstock. Diet A was sole squid meat. Diets B and C were supplemented with astaxanthin 50 and 100 mg kg^?1 respectively. Diets D and E were supplemented with HUFA 5 and 10 g kg^?1 and astaxanthin 50 mg kg^?1 respectively. The result showed that the group fed diet E had the best reproductive performance in all experimental groups. It had a higher proportion of spawns (71.5%), spawning rate (0.047), a shorter latency period (7.7±0.3 d), higher absolute fecundity (× 10³) (361.6±5.5) and egg production/female (× 10³) (597.0±18.0) than all the other experimental groups. The fatty acid composition in broodstock diets strongly affected the tissue and fecundity of broodstock. Good correlations between the content of 20:4n‐6 in eggs and the fecundity (r²=0.6109) and egg production (r²=0.9876) of broodstock were found. On the other hand, 22:6n‐3 and DHA/EPA ratio was negatively correlated with the fecundity of broodstock (r²=0.5362, 0.8702 respectively). The result also showed that the balance between n‐3 and n‐6 fatty acid families, total polyunsaturated fatty acids and total saturated fatty acid and 20:5n‐3 (EPA) and 22:6n‐3 (DHA) may play vital roles in maturation and reproductive performance of P. monodon broodstock.  相似文献   

Interaction between energy level in the diet and environmental temperature on the utilization of energy in growing pigs   总被引：2，自引：0，他引：2  

J Noblet  J Le Dividich  T Bikawa 《Journal of animal science》1985,61(2):452-459

Thirty-two pigs weighing approximately 50 kg were maintained in respiration chambers to measure their heat production and the partition of energy retention between protein and fat deposition at two environmental temperatures (23 and 13 C) and with two energy levels in the diet: 3.39 (HE) and 2.92 (LE) Mcal ME/kg. From energy balance data, maintenance requirements (MEm) and the efficiency (k) of energy (ME) utilization for energy deposition were calculated for each treatment. For both diets, MEm averaged 122 kcal ME/kg.75 at 23 C, the rate of increase of MEm being 3.7 kcal ME/kg.75 for each 1 C decrease in the environmental temperature. At 23 C, k was higher with the HE diet (.81 vs .55) and similar for both diets (.78) at 13 C. At comparable ME intakes, heat production was higher with the LE diet at 23 C, and the rate of increase of heat production between 23 and 13 C was lower with the LE diet (1 kcal/kg.75) than with the HE diet (3 kcal/kg.75), resulting in similar heat production at 13 C for both diets. This resulted in an interaction (P less than .01) between temperature and diet on heat production. Protein retention was lower (P less than .01) at 13 C but unaffected by diet at both temperatures. This resulted in an interaction (P less than .01) between temperature and diet on fat retention. Consequently, energy of LE and HE diets was similarly utilized at 13 C, while at 23 C, the HE diet was better utilized. The comparison between these results and those obtained in growth experiments is discussed.  相似文献   

基于ELES模型的农民灌溉水价支付能力水平界定     

陈丹  陈菁  胡乐  陈运怀 《节水灌溉》2009,(7)

从支付能力的角度定量研究农民对灌溉水价的承受能力,采用扩展线性支出系统(ELES)模型,通过实例计算分析了农户总体收支及水费支出、农民基本消费需求支出和支付能力水平的界定标准等,并分析了支付能力的主要影响因素.结果表明:研究区域内农民年人均纯收入774元和1 300元是支付能力水平的分界线,无支付能力、有一定支付能力和有支付能力的农户分别占6.1%、9.7%和84.2%;支付能力较低的农户均以农业生产为主要收入来源;不同支付能力组之间农民年人均水费支出与平均水费支出均无显著差异;耕地面积、农业收入和非农业收入对农民支付能力具有显著的影响.  相似文献   

水轮机组振动故障诊断和试验研究   总被引：1，自引：0，他引：1  

敏政  王异凡  王乐  邵翔宇 《中国农村水利水电》2009,(10):140-142

振动故障严重影响水轮机组的正常运行和发电效益,要清除振动故障，必须认清振动的原因，找准振源。从机械、水力、电气等三个方面分析了引起水轮机组振动的主要原因及特征。介绍了转速、励磁和负荷试验在水轮机振动故障诊断中的应用，通过分析某电站现场振动试验中各部位振动及水压脉动的幅值随机组运行工况变化的规律，找出了引起该机组振动的原因和处理方法，具体说明了试验法在水轮机组振动故障诊断和处理中的应用。  相似文献   

Assessment of Rhizospheric Microorganisms of Transgenic Populus tomentosa with Cowpea Trypsin Inhibitor (CpTI) Gene     

Zhang Qian  Zhang Zhi-yi  Lin Shan-zhi  Lin Yuan-Zhen  Yang Le 《中国林学(英文版)》2005,7(3):28-34

To have a preliminary insight into biosafety of genetically transformed hybrid triploid poplars (Populus tomentosa × P. bolleana) × P. tomentosa with the cowpea trypsin inhibitor (CpTI) gene, two layers of rhizospheric soil (from 0 to 20 cm deep and from 20 to 40 cm deep, respectively) were collected for microorganism culture, counting assay and PCR analysis to assess the poten-tial impact of transgenic poplars on non-target microorganism population and transgene dispersal. When the same soil layer of suspension stock solution was diluted at both 1:1 000 and 1:10 000 rates, there were no significant differences in bacterium colony numbers between the inoculation plates of both transgenic and non-transgenic poplars. The uniform results were revealed for both soil layer suspension solutions of identical poplars at both dilution rates except for non-transgenic poplars at 1:10 000 dilution rates from the same type of soil. No significant variation in morphology of both Gram-positive and Gram-negative bacteria was observed under the microscope. The potential transgene dispersal from root exudates or fallen leaves to non-target microbes was repudiated by PCR analysis, in which no CpTI gene specific DNA band was amplified for 15 sites of transgenic rhizospheric soil samples. It can be concluded that transgenic poplar with the CpTI gene has no severe impact on rhizospheric microorganisms and is tentatively safe to surrounding soil micro-ecosystem.  相似文献   

肚倍蚜,美灰藓最佳生态条件与肚倍基地建设   总被引：2，自引：0，他引：2  

郑德国  王贤斌 《湖北林业科技》1997,(3):8-12

肚倍蚜，美灰藓最佳生态条件研究表明，由光照强度、湿度以及风速等因素决定的环境是制约肚倍丰产、稳产的关键；据此对肚倍基地建设提出若干建议。  相似文献   

Micropropagation and tissue culture of Eucalyptus-a review     

Le Roux JJ  Staden JV 《Tree physiology》1991,9(4):435-477

Micropropagation has the potential to provide very high multiplication rates of selected tree genotypes, with resulting short-term silvicultural gains. Aseptic cultures have been established from seeds, seedlings, shoots, flowers and lignotubers. Callus cultures have been established from a wide range of tissue sources for at least 30 species of Eucalyptus. Plant regeneration from callus was successful for 12 of these species. Micropropagation through axillary proliferation, or adventitious shoot proliferation on nodal explants, or both, has been successful. An agar-based medium of Murashige and Skoog with a low auxin/cytokinin ratio is most commonly used for shoot multiplication. Vitrification and shoot senescence remain problems. Gibberellic acid was added in some media to stimulate shoot elongation. Various media are used for in vitro root initiation. Suspension and protoplast cultures have been achieved and plants have been regenerated from protoplasts. In vitro techniques are presently being applied to Eucalyptus to achieve genetic transformations.  相似文献   

Parental participation in progeny and effective population sizes in experimental seed orchards of wild cherry Prunus avium L. (Batsch)     

Stéphanie Mariette  Emilie Balsemin  Solenn Stoeckel  Muriel Tavaud  Hervé Le Bouler  Frédérique Santi  Michel Verger 《Annals of Forest Science》2007,64(5):533-539

Parents and progenies genetic diversity, and male and female contributions to the seed crop were assessed in three experimental Prunus avium seed orchards. Collected data were used to compare different effective population sizes, based on phenological, seed crop and paternity analysis. Our results did not show any difference of genetic diversity between parents and progenies. A limited pollen pollution was detected. We showed that distance and coflowering among clones had a significant effect on effective pollination, and a significant effect of the production of flowers was revealed in one of the seed orchards. Our study also revealed a quite low number of effective size of fathers per mother, but high effective sizes of mothers, fathers and parents at the level of the seed orchard. Finally, the calculation of effective size of mothers, fathers and parents was not highly modified when having the complete information based on the paternity analysis.  相似文献