Tissue concentrations of RNA and protein for juvenile brook trout (Salvelinus fontinalis): lagged responses to fluctuations in food availability

To be useful as short-term indices of nutritional status when food availability varies, wet weight-at-length and tissue concentrations of nucleic acids and protein must covary closely with a fish's recent feeding history. We measured changes in these indices for young brook trout (Salvelinus fontinalis) (fork length: 20–34 mm) reared under alternating, 4 to 5 d periods of food provisioning and food deprivation. Weight-at-length corresponded closely with current feeding conditions, being higher when the trout were fed than when they were deprived. Concentrations of RNA and protein, however, did not correspond closely with current feeding conditions. Instead, there were significant carry-over effects whereby responses to feeding conditions experienced in one treatment period were not exhibited until the following treatment period. Food provisioning had positive carry-over effects on concentrations of RNA and protein while food deprivation had negative carry-over effects. Consequently, food-deprived trout sometimes had higher concentrations of RNA and protein than well fed trout. Since wild fish may experience short-term fluctuations in food availability, lagged responses in concentrations of nucleic acids or protein like those reported here could hamper attempts to use these biochemical measures to assess the nutritional status of juvenile fish in the field.Author to whom all correspondence should be addressed.     

供体细胞培养处理方法对水牛核移植效果的影响

以经常规培养法 (DMEM 10 % FCS)、血清饥饿法 (DMEM 0 .5 % FCS培养 5～ 10 d)和 Apidicolin- APD结合血清饥饿法 (0 .1mg/ L APD培养 2 4 h,DMEM 0 .5 % FCS培养 1～ 18d)培养处理的水牛卵巢颗粒细胞和水牛成体耳部成纤维细胞作供核 ,分别采取带下注核法和胞质内注核法进行核移植。同一供核细胞各处理组间的核移植胚融合率 (以颗粒细胞作供核 )以及重组胚的囊胚发育率无明显差异 (P>0 .0 5 ) ,但经 APD 0 .5 % FCS培养处理供体细胞核移植后的分裂率显著高于其他组 (P<0 .0 5 )。用 7%乙醇处理的成体耳部成纤维细胞进行核移植 ,其重组胚的分裂率和囊胚发育率与对照组 (不含乙醇 )均无明显差异 (P>0 .0 5 )。结果表明 ,(1)血清饥饿处理水牛供体细胞对其核移植效果没有影响 ;(2 ) DNA合成抑制剂 APD结合血清饥饿培养处理水牛颗粒细胞和成体耳部成纤维细胞 ,可提高其核移植效果 ;(3)乙醇预激活处理水牛成体耳部成纤维细胞 ,对其核移植效果没有影响     

When insecticide spraying ceases prematurely Tetranychus urticae mites are not killed by predators,they wither and die in situ

An outbreak of spider mites on apple trees sprayed with insecticide collapsed when spraying was stopped prematurely. But mites were not taken by predators. They remained at their feeding site but became torpid, withered and died. This observation supports earlier evidence that mites increase because the application of insecticide caused protein in the leaves to break down releasing soluble amino acids into the sap. This improved the nutrition of the mites, allowing them to increase. But when spraying was stopped at the height of an outbreak this flow of amino acids ceased and the mites starved from the consequent decline in their nitrogen nutrition.     

Uptake and metabolism of a particulate form of ascorbic acid by Artemia nauplii and juveniles

A study was conducted to establish whether a particulate form of ascorbic acid (AA), ascorbyl‐2‐phosphate (A2P), could be used to enrich Artemia. In the first experiment, we examined the efficiency of A2P conversion to and maintenance of AA by juvenile Artemia (1.5 mm, 5‐day‐old) held at 9000 L^?1 and 28 °C for 24 h. Maximal uptake and assimilation was >10 000 μg AA g^?1 dry weight (dw) (representing >1%Artemia dw) at enrichment rates of ≥1.2 g A2P L^?1. In the second experiment, a similar biomass of instar II/III nauplii (1 mm, 2‐day‐old) and juvenile (2.5 mm, 8‐day‐old) Artemia were enriched for 6 or 24 h at 28 °C before starvation for 6 or 24 h at 18 or 28 °C. At 0 h and after 6 and 24 h enrichment, AA levels were 485, 3468 and 11 080 μg g^?1 dw in nauplii and 122, 4286 and 12 470 μg g^?1 dw in juveniles. When Artemia nauplii or juveniles were enriched for 6 h and starved for 6 h at 18 or 28 °C, there was no significant reduction in AA. Continuation of starvation to 24 h at 18 and 28 °C reduced the level of AA to 3367 and 2482 μg g^?1 dw in nauplii and 3068 and 2286 μg g^?1 dw in juveniles. After 24 h enrichment, 6 h of starvation at 18 and 28 °C reduced AA to 8847 and 7899 μg g^?1 dw in nauplii and to 9053 and 8199 μg g^?1 dw in juveniles. Continuation of starvation to 24 h at 18 and 28 °C further reduced AA levels in nauplii to 6977 and 4078 μg g^?1 dw and to 7583 and 5114 μg g^?1 dw in juveniles. This study demonstrated that A2P could be assimilated as AA in the body tissue of different‐sized Artemia in a dose‐dependant manner and AA was depleted during starvation depending on time and temperature.     

Effects of Phosphate Starvation Responses Gene OsSQD2.1 on Growth in Rice

【Objective】This work aims at confirming the effects of gene OsSQD2.1, involved in phosphate starvation responses on rice growth so as to reveal its function. 【Method】The bioinformatics method was used to determine the OsSQD2.1 gene and its protein structure and the cis-acting elements on the OsSQD2.1 promoter. The expression of OsSQD2.1 under different deficiency conditions was measured by real-time PCR. For an insight into the effects of OsSQD2.1 on the growth and photosynthesis of transgenic plants, we determined the phenotype, phosphorus content and net photosynthetic rate of DNA insertion mutants and silencing interfering materials at different growth stages. 【Result】The coding region of the OsSQD2.1 gene is 3548 bp in length and it is located on chromosome 1, with 11 exons and 10 introns. OsSQD2.1 belongs to the glycosyltransferase family; OsSQD2.1 promoter contains multiple reported cis-acting elements responsive to phosphorus deficiency; OsSQD2.1 was induced by phosphorus deficiency and inhibited by sulfur deficiency. Compared with the wild type, the shoot length and primary root length during the vegetative growth period in the mutant or silencing materials were significantly lower than the wild type. During the reproductive growth, the plant height as well as 1000-grain weight of the mutant or silencing material was significantly lower than that of wild type, and there was no significant difference in seed setting rate; The total phosphorus contents in the leaves were not significantly different in the wild type under the phosphorus deficiency condition. In addition, the net photosynthetic rate of the seedling and mature mutants was significantly lower than that of the wild type, and it was presumed that OsSQD2.1 affected the net photosynthetic rate of rice. 【Conclusion】The results confirm that OsSQD2.1 is phosphorus deficiency-responsive and affects rice growth.     

饥饿对卵形鲳鲹幼鱼不同组织抗氧化能力、Na＋／K＋-ATP酶活力和鱼体生化组成的影响

卵形鲳鲹（Trachinotusovatus）幼鱼经短期饥饿处理后测定其鳃、肝脏和肌肉中的总抗氧化能力（T-AOC）、超氧化物歧化酶（SOD）活力、丙二醛（MDA）质量摩尔浓度、Na＋／K＋-ATP酶活力和全鱼生化组成。结果显示,饥饿7d后鳃丝和肌肉的T-AOC显著升高,肝脏的T-AOC显著下降（P〈0．01）;鳃丝和肌肉SOD活力均显著升高（P〈0．01）,肝脏的SOD活力变化不显著（P〉0．05）;鳃丝、肝脏和肌肉的b（MDA）在饥饿后上升,鳃丝b（MDA）与对照组差异极显著（P〈0．01）,肝脏b（MDA）与对照组相比差异显著（P〈0．05）,肌肉b（MDA）差异不显著（P〉0．05）。饥饿8d后鳃丝Na＋／K＋-ATP酶活力显著升高（P〈0．01）,肝脏Na＋／K＋-ATP酶活力显著下降（P〈0．01）,肌肉Na＋／K＋-ATP酶活力也有所升高（P〉0．05）;饥饿后鱼体水分质量分数上升,粗蛋白质量分数、粗脂肪质量分数和能值下降,而且相对损失率是粗脂肪〉粗蛋白,表明卵形鲳鲹幼鱼在饥饿早期主要消耗脂肪向机体提供能量,随着饥饿时间的延长,蛋白质将被消耗。     

卵形鲳鲹消化酶活力的研究Ⅵ 饥饿对幼鱼存活和消化酶活力的影响

研究了饥饿对卵形鲳鲹(Trachinotus ovatus)消化器官中主要消化酶(蛋白酶、淀粉酶、脂肪酶)活力的影响。在水温25±0.5℃、盐度20±1条件下,对卵形鲳鲹幼鱼进行短期饥饿处理(0 d、3 d、6 d、9 d、12 d),并分别测定卵形鲳鲹幼鱼的比内脏重与蛋白酶、淀粉酶和脂肪酶3种消化酶的活力。结果表明,随着饥饿时间的延长,卵形鲳鲹幼鱼的比内脏重不断下降,饥饿第0～6天下降速度最快(P﹤0.01),6 d后下降不显著(P﹥0.05);蛋白酶活力表现为饥饿第0～6天不断上升,第9天下降,第12天又显著升高(P﹤0.01),并且饥饿后的蛋白酶活力始终高于对照组(P﹤0.01);淀粉酶活力不断下降,并在第3天下降最显著(P﹤0.01);脂肪酶活力在饥饿前9 d总体上下降,第12天活力明显上升并高于对照组(P﹤0.01)。饥饿第8天开始出现幼鱼死亡,至第12天幼鱼的存活率为64.67%,表明第8天是卵形鲳鲹幼鱼饥饿致死的临界期。     

玉米细根形成和土壤中无机磷分级平衡对缺磷的特异性响应

Plants have diverse strategies to cope with phosphorus (P) deficiency. To better understand how maize responds to P deficiency, a field experiment with two P levels, 0 and 100 kg P2O5 ha-1 (P0 and P100, respectively), was carried out as a part of a long-term Pfertilizer field trial. Plant and soil analyses showed that P-deficient maize reduced its growth rate, increased P use efficiency, and formed more thin roots with the diameter less than 0.6 mm at jointing and silking stages, compared to the plants treated with P100. Further, there were no differences in major inorganic P fractions (Ca 2 -P, Ca 8 -P, Al-P, Fe-P, occluded P and Ca 10 -P) between the rhizospheric and bulk soils at each harvest, even when soil Olsen-P was only 1.38 mg kg-1 . These results suggested that maize responded to P deficiency by reducing the internal P demand for growth and increasing P acquisition ability by favorable root morphological alteration at low carbon cost.     

饥饿对白鲫能量物质消耗的影响

以性成熟的雌性白鲫(Carassius auratus cuvieri)作为试验对象,研究其肌肉、卵巢和肠系膜脂肪等组织能量物质消耗的变化过程和分配关系。分别在饥饿1 d、2 d、4 d、8 d、16 d、24 d、32 d、40 d取样,测定全鱼、肌肉和卵巢的水分、粗蛋白质、粗脂肪和灰分含量。结果显示:全鱼、肌肉的含水量和灰分含量随饥饿时间的延长而升高,而粗蛋白和粗脂肪含量随饥饿时间的延长而减少。在40 d的饥饿中消耗了总蛋白质的7.54%,总粗脂肪的50.94%,其中有17.43%的总蛋白质和27.98%总脂肪在肌肉中被消耗掉。鱼体消耗的蛋白质75%~100%来自肌肉,消耗的脂肪仅有不到10%来自肌肉。脂肪作为主要能量物质被消耗,但也伴随一定量的蛋白质被消耗,其消耗速度不均匀。脂肪在8~16 d出现一个消耗高峰期,蛋白质在24~32 d的消耗量较大。在试验期内其丰满度保持相对稳定,肠系膜脂肪明显减少。饥饿期间卵巢的蛋白质和脂肪含量相对稳定。对照组的水分、粗蛋白质、粗脂肪和灰分含量在试验期内比较稳定。