不同品种苦荞中的4种活性黄酮含量

利用HPLC测定21个不同品种苦荞籽粉和麸皮中芦丁、山奈酚-3-芸香糖苷、槲皮素和山奈酚的含量.采用RP-HPLC,用Damonsil C18色谱柱(4.6 mm×250 mm,5μm),以乙腈-0.2%冰醋酸水溶液为流动相进行梯度洗脱,流速为1.0 m L/min,检测波长为354 nm,柱温30℃.结果显示,在室温状态下,21种不同品种的苦荞种子中水分含量在4.907 3%-6.993 6%之间,恒重状态下,麸皮质量分数为21.84%-30.03%,麸皮重量约占苦荞籽粒质量的1/4.芦丁、山奈酚-3-芸香糖苷、槲皮素和山奈酚的线性范围分别在20-400μg/m L、2-40μg/m L、1-20μg/m L、0.5-10μg/m L;不同品种苦荞籽粉中,芦丁、山奈酚-3-芸香糖苷、槲皮素和山奈酚的含量范围分别为12.137 0-20.318 6 mg/g、1.478 7-2.871 9 mg/g、0.014 6-0.901 5 mg/g、0-0.015 9 mg/g,4种主要黄酮的总含量为14.015 1-22.871 7 mg/g;麸皮中芦丁、山奈酚-3-芸香糖苷、槲皮素和山奈酚的含量范围分别为4.269 0-12.118 9 mg/g、0.258 5-1.014 9 mg/g、0.061 8-0.735 4 mg/g、0-0.026 3 mg/g,4种主要黄酮的总含量为4.651 1-13.148 6 mg/g.本研究表明,无论在籽粉还是麸皮中,芦丁都是含量最高的黄酮,其次为山奈酚-3-芸香糖苷和槲皮素,山奈酚的含量在万分之一以下;本研究可为苦荞籽粉和麸皮中主要黄酮的开发和优良品种的利用提供重要依据.     

雷州无瓣海桑群落7种元素的生物累积和循环

在雷州市附城镇岚北人工生态恢复的 7a生无瓣海桑群落生物量调查的基础上 ,对所采集的无瓣海桑进行了植物体各组分样品的灰分和元素含量测定与循环分析 ,结果表明 :无瓣海桑植物体不同组分的灰分含量范围为 2 .2 7%～ 2 6 .4 1% ,以细根的含量最高 ,枯枝的含量最低 .植物体各组分中 7种元素质量分数范围分别为K 0 .11%～ 1.5 6 % ,Na0 .11%～ 1.6 6 % ,Ca 0 .2 0 %～ 2 .6 6 % ,Mg 0 .15 %～ 1.5 9% ,Fe 0 .0 4× 10 -3 ～ 9.6 4× 10 -3 ,Zn 0 .0 5× 10 -4～ 1.0 3× 10 -4,Cu0 .16× 10 -5～ 1.5 0× 10 -5.其加权平均的富集系数为 0 .0 5～ 9.70 ,其中Ca >K >Cu >Na >Mg>Zn >Fe .群落现存生物量中的累积储量分别为K 10 9.76gm-2 ,Ca 138.89gm-2 ,Na 86 .5 7gm-2 ,Mg 81.0 7gm-2 ,Fe 13.139gm-2 ,Zn 0 .4 83gm-2 ,Cu 0 .10 8gm-2 .群落 2 0 0 1年的元素存留累积储量分别为Ca4 1.6 8gm-2 ,K 37.2 4gm-2 ,Mg 2 7.33gm-2 ,Na2 5 .5 6gm-2 ,Fe 4 .2 75gm-2 ,Zn 0 .188gm-2 ,Cu 0 .0 39gm-2 .2 0 0 1年归还量分别为Ca 2 8.5 9gm-2 ,K 16 .83gm-2 ,Mg 12 .0 7gm-2 ,Na 11.5 8gm-2 ,Fe 0 .916gm-2 ,Zn 0 .14 1gm-2 ,Cu 0 .0 2 6gm-2 .年吸收量分别为Ca 70 .2 7gm-2 ,K 5 4 .0 7gm-2 ,Mg 39.4 0gm-2 ,Na 37.1     

川西米亚罗地区亚高山针叶林建群种云杉土壤种子库研究

对川西米亚罗地区天然亚高山针叶林云杉种群的种子雨和土壤种子库进行了研究 .结果表明 :云杉种子雨过程从 2 0 0 2年 10月初到翌年 1月初 ,种子雨雨量 (n)为 5 79.99± 110 .84粒 /m2 ,其中种子下落主要集中在 11月 ,占种子雨总量的 5 7.80 % .种子雨分布格局呈集群分布 .于 2 0 0 3年春季 (3月 )和夏季 (8月 )两次对该天然云杉林土壤种子库取样 ,土壤种子库大小分别为 4 72 .8± 74 .82粒 /m2 和 185 .5± 89.95粒 /m2 ;腐烂种子分别为 39.6 0± 13.2 4粒 /m2和 12 0 .0± 6 3.39粒 /m2 ,腐烂种子比例由 8.39%增加到 6 4 .6 9% ;空粒种子分别为 118.8± 4 4 .6 6粒 /m2 和 6 5 .5± 2 6 .4 8粒 /m2 ,所占比例从 2 5 .14 %增加到 35 .31% .两次取样结果都表明 ,种子库种子主要集中在枯枝落叶层 ,分别占6 6 .17%和 6 6 .0 3% ,0～ 2cm层占 2 4 .73%和 2 3.4 5 % ,2～ 5cm层占 9.10 %和 10 .5 1% .到 8月 ,土壤中几乎所有云杉种子都失去活力 ,说明云杉种子库属于Thompson和Grime定义的第Ⅱ类型 ,即土壤种子库仅在冬季存在 ,在春季萌发 .土壤中春、夏、秋季种子很少或几乎没有 .林下云杉幼苗在 2 0 0 3年 6月 3号开始出现 ,在 6月中旬左右到达出苗高峰 ,累计平均幼苗数 4 .35株 /m2 .在川西米亚罗地区天然     

Cu2+,Cd2+和Cr(Ⅵ)抑制沼泽红假单胞菌生长的毒性效应

运用标准方法进行有毒化学品对水生生物急性毒性实验 ,得到Cu2 + ,Cd2 + ,Cr(Ⅵ )对光合细菌沼泽红假单胞菌生长抑制作用的 96h剂量反应方程 ,分别为 :y =- 1.72 6 7x +8.70 0 4 ,R2 =0 .96 5 5c(Cu2 + ) ;y =$C1.15 5 1x +8.9996 ,R2 =0 .92 5 2c(Cd2 + ) ;y=$C1.342 7x +10 .785 ,R2 =0 .975 8c〔Cr(Ⅵ )〕 ,由此计算出Cu2 + ,Cd2 + ,Cr(Ⅵ )的 96h -EC50 分别为 2 .172× 10 -6mol/L ,2 .5 6 6× 10 -5mol/L和 3.92 6× 10 -4mol/L .从而得出它们对沼泽红假单胞菌生长毒性作用大小的顺序为Cu2 + >Cd2 + >Cr(Ⅵ ) .表 2参 11     

铒钇异核脯氨酸配合物:[ErY(Pro)4(H2O)8](ClO4)6的合成及晶体结构

为了研究稀土离子与氨基酸 (Pro)的相互作用 ,在pH≈ 3.5水溶液中合成了高氯酸八水·(脯氨酸 )合铱 (Ⅲ )铒 (Ⅲ ) ,获得了单晶 ,并经四圆衍射仪测定了结构 .配合物组成为C2 0 H52 Cl6ErN4 O4 0 Y ,属三斜晶系 ,P1空间群 .晶胞参数a =0 .986 0 (2 )°nm ,b =1.30 2 0 (5 )nm ,c=1.36 32 (5 )nm ,α =10 9.32 (3)° ,β=110 .19(2 )° ,γ =10 0 .96 (2 )°,V =1.45 6 (1)nm3,Z =1,Dc=1.6 6 3g/cm3,μ =2 .797mm-1,F(0 0 0 ) =72 9.配合物分子中 ,Y3 ‘、Er3 在相应位置上出现的几率各为 5 0 % ,相邻两个金属离子被两个以桥式双齿配位的Pro分子连接 ,每个金属离子除了与 4个羧基O配位外 ,还与 4个水分子的氧配位 ,配位数为 8,形成变形的四方反棱柱 .图 4表 3参 10     

模拟酸雨对珍稀濒危植物红豆杉幼苗的影响研究

利用模拟酸雨实验对珍稀濒危植物曼地亚红豆杉和南方红豆杉生长及生理生化指标进行研究。结果表明,pH4.5的模拟酸雨促进了曼地亚红豆杉(Taxus media)和南方红豆杉(T.mairei)的株高生长(与对照相比分别促进了19%和72%),pH3.5的模拟酸雨对其有一定的影响,但不显著。pH4.5和pH3.5的酸雨处理下,曼地亚红豆杉基径比对照分别下降了46%和42%;南方红豆杉的相应值分别是34%和43%。总的来说,模拟酸雨促进了这两种红豆杉叶绿素的质量分数,类胡萝卜素的质量分数变化因种而异。酸雨处理提高了曼地亚红豆杉抗氧化系统酶活性,与对照相比约提高了5%～142%;南方红豆杉的相应值为-16%～35%。曼地亚红豆杉游离脯铵酸和丙二醛(MDA)的质量分数比对照提高了13%～73%;而南方红豆杉的相应质量分数基本等于或低于对照。与南方红豆杉相比,曼地亚红豆杉对酸雨更加敏感。     

大鸨生长期能量代谢和蛋白质沉积量的初步研究

对不同日龄笼养大鸨 (Otistarda)的能量代谢和蛋白质沉积量进行研究 .结果表明 ,5 0日龄、70日龄、30 0日龄和 4 0 0日龄雄性大鸨的能量日摄入量分别为 14 98.9kJ、2 376 .2kJ、2 397.4kJ和 2 4 6 5 .9kJ;能量代谢率分别为 82 .3%、81.8%、81.8%和 83.1% ;蛋白质的日沉积量分别为 5 .8g、13.4g、15 .8g和 13.5g .表 3参 9     

高寒小嵩草草甸种子库和种子雨动态分析

对小嵩草草甸种子库的大小和物种组成及与种子雨、地上植被的关系进行了初步研究 .结果表明 ,返青期和枯黄期小嵩草草甸种子库单位体积 (1.0m× 1.0m× 0 .1m)分别有种子nf=10 5 5 0粒和nk=13 815粒 ,分别由 2 2种和 2 4种植物组成 ,分属 9个科 .其中 ,莎草科、豆科和龙胆科占优势 ,禾本科所占比例较小 .每平方米种子雨nr=8436 .4粒 ,由2 5种植物组成 ,分属 10个科 ,莎草科和禾本科所占比例较大 .种子库和种子雨在物种组成上有一定的相似性 (r =0 .76 0 0 ,P <0 .0 1) ,二者共有 19个种 ,分别占种子库和种子雨物种总数的 82 .6 1%和 90 .48% .地上植被与种子库的相似性较小 ,地上植被中有 43.2 4%和 5 1.35 %的植物分别在返青期和枯黄期种子库中出现 ,6 0 %的植物出现于种子雨中 .在物种分布和优势度上 ,地上植被与种子雨间一致性较高 ,但它们与种子库间有一定的分歧 .从地上植被到返青期时的种子库 ,物种多样性降低了 1.6 1% ,从而说明种子库不仅是地上植被补充更新的源泉之一 ,而且是维持植物物种多样性的一种机制 .图 3参 13     

固定CO2氢细菌的筛选及其培养条件优化

从土壤中分离筛选到一株高效固定CO2 的氢氧化细菌—专性化能自养菌BHA 15 ,在最佳培养条件下(培养基 ρ/gL-1:NH4 Cl 4.0 ,Na2 HPO4 ·12H2 O 0 .75 ,KH2 PO4 0 .5 ,MgSO4 ·7H2 O 0 .3;V(H2 )∶V(O2 )∶V(CO2 ) =3 .5∶1∶1;pH =7;最适生长温度θ =30℃ ) ,密闭摇瓶中恒温 (30℃ )培养 40h后 ,菌体浓度 ρ(DW)达 1.6mg/mL ,菌体蛋白含量 71.8% .图 7表 2参 12     

沉积物中腐殖质对铜毒性的影响

东湖沉积物中掺入腐殖质与铜 ,得到总有机碳 (TOC) 1.4 5 %～ 5 .72 %、总铜 (TCu) 12 0～ 2 70 0mg/kg的污染沉积物样品 ,离心法制取沉积物间隙水 .间隙水对大型溞 (Daphniamagna)进行 4 8h急性毒性试验 .沉积物及间隙水的化学分析表明 :间隙水中可溶性有机碳 (DOC)、铜 (Cu)、铁 (Fe)、锰 (Mn)、钙 (Ca)与沉积物中TOC和TCu含量关系呈现不同的变化规律 .多元分析表明 :间隙水中铜对大型溞的急性毒性 ,随沉积物中TOC含量的升高而减弱 ,随沉积物中总铜含量的增加而增强 ,多元回归方程为 :LC50 =- 0 .13179+0 .0 780 7[TOC]- 0 .0 0 0 12 [TCu]+0 .0 4 6 5 3[DOC]- 0 .0 80 4 5 [Cu]+0 .0 0 794 [Fe]+0 .0 36 6 [Ca],P =0 .0 0 0 0 相似文献   

Feeding of calanoid copepods in relation to Phaeocystis pouchetii blooms in the German Wadden Sea area off Sylt

Surface sediments from the Svartnes basin (195 m deep) in Balsfjorden, northern Norway (ca. 70°N), were partially characterized to assess the nature and origin of the organic material present and its potential nutritive value for sediment-ingesting animals. Seasonal analyses were carried out on material collected between May 1979 and August 1980 for total organic matter, organic C and N, acid-extractable amino acids and lipids extractable with chloroform:methanol. Little or no seasonal variation was seen in any of the parameters analysed. The mean apparent organic content was 9.3% of sediment dry weight, the organic C content was 2.38%, the organic N content was 0.26% and the C:N ratio was 9.1:1. Acid hydrolysis of sediment yielded 575 mg of amino acids and 41 mg of NH₃ per 100 g sediment dry weight, the composition of the amino acids being similar to that of nutritionally highquality animal or microbial protein. Glucoseamine was not detected in acid hydrolysates of sediment, consistent with the absence of chitin. Chloroform:methanol extraction yielded 133 mg of material per 100 g sediment dry weight, 62% of which was accounted for by saponifiable lipids (fatty acids) and non-saponifiable lipids present in approximately equal amounts. Fatty alcohols accounted for 30% of the non-saponifiable lipids and phytol accounted for 40% of the fatty alcohols. Small amounts of very long-chain fatty alcohols characteristic of terrestrial plants were present, but long-chain monounsaturated fatty alcohols characteristic of marine zooplankton were essentially absent. Very small quantities of long-chain ketones characteristic of marine coccolithophores were detected. The major fatty acids present in sediments were 16:0, 14:0, 16:1 (n-7) and 18:1 (n-9), and 11% of the total fatty acids were comprised of a mixture of odd-numbered straight-chain and branched-chain moieties characteristic of micro-organisms. The data point to small amounts of material characteristic of marine and terrestrial photosynthetic organisms being present in sediments at any given time, whereas material characteristic of marine zooplankton is not present. The presence of material characteristic of micro-organisms is consistent with conversion of sedimenting material into a pool of sediment micro-organisms. Although the biological availability to sediment-ingesting organisms of the esterified fatty acids and the acid-extractable amino acids in sediments remains to be assessed, the maximum amounts available are equivalent to approximately 60 mg of polar lipid and 575 mg of protein per 100 g sediment dry weight. These amounts are small in relation to the production rates in the photic zone of the fjord, implying that the bulk of the energy flow in Balsfjorden occurs in its relatively short pelagic food chains.     

Insights into the changes of amino acids,microbial community,and enzymatic activities related with the nutrient quality of product during the composting of food waste

● The highest seed germination index was achieved at 0.3 g/g total solids of food waste. ● Proline was identified as the key amino acid related with the composting process. ● Amino acid metabolism sequences predominated during the whole composting process. This study systematically investigated the changes of amino acids as the composting process of food waste proceeded. It is found that the addition of 0.3 g/g total solids of food waste achieved the highest seed germination index of the product (268 %). The microbial community results indicated that the abundance of amino acid metabolism sequences remained at high levels during the whole composting process. Proline was identified as the key amino acid related with the nutrient quality of product during the composting of food waste. Further plant germination and hydroponic experiments found, that compared with those without the addition of proline, the addition of 50 mg/L proline increased seed germination rate by 20 %, increased shoot length by 3 %, increased root biomass of seedlings by 82 %, and increased leaf biomass of seedlings by 76 %, respectively. Firmicutes, γ-Pseudomonadota, Chloroflexi and Planctomycetes were the key identified bacteria related with the increase of proline during the composting of food waste. Meanwhile, the enzymatic tests of the activities of superoxide dismutase, peroxidase and malondialdehyde indicated that proline did not cause oxidative damage on the growth of plants. This study provided novel insights into the changes of amino acids, microbial community, and enzymatic activities related with the nutrient quality of product during the composting of food waste.     

微量元素对红豆杉菌根菌生长的影响

微量元素对植物的生长发育有着十分重要的意义。对太行山野生红豆杉(Taxus chinensis var.mairei)菌根菌菌丝在分别加有硫酸锌、钼酸铵以及硫酸亚铁的PDA培养基中的生长发育状况进行了试验研究。所得数据同PDA对照组进行比较分析后,结果表明:Mo元素对红豆杉菌根菌菌丝的生长发育有很好的促进作用;Fe元素明显地促进红豆杉菌根菌菌丝的生长发育;Zn元素在一定范围内对红豆杉菌根菌菌丝的生长发育有一定的抑制作用。实验结果揭示出红豆杉菌根菌生长发育的一些营养因素。     

4种鸢尾属植物对铅锌矿区土壤中重金属的富集特征和修复潜力

通过野外调查和实地修复铅锌矿污染土壤试验,研究了铅锌矿区排污渠污水及底泥中Pb、Zn、Cu、Cd含量和分布特征以及4种鸢尾属植物马蔺（Iris lactea var.chinensis）、黄菖蒲（Iris pseudacorus L.）、溪荪（Iris sanguinea Donn ex Horn.）、花菖蒲（Iris ensata Thunb.）对Pb、Zn、Cu、Cd的积累能力和土壤修复效率差异。结果表明,离污染源越近,重金属污染越严重。Pb、Zn、Cu、Cd4种重金属均大部分沉积在排污水渠的底泥中,污水中Pb严重污染,超标达120倍,底泥中Pb、Zn、Cu、Cd质量分数分别超标1.5倍、1.7倍、1.6倍和1.7倍。排污渠岸土壤Pb、Zn、Cu、Cd质量分数也明显超过了国家规定的土壤环境质量Ⅱ级标准1～5倍。种植4种鸢尾属植物后,土壤中Pb、Zn、Cu、Cd质量分数有所降低。其中,种植马蔺1个月后土壤Pb、Cu、Cd修复效率分别为8.13%、2.45%和22.3%。黄菖蒲和花菖蒲对Zn的修复效率相对较高。4种鸢尾属植物中马蔺对Pb、Cd的吸收能力最强,马蔺地上部（叶、茎）Pb质量分数达983mg·kg-1,且转运系数大于1,是一种潜在的Pb积累植物,黄菖蒲、溪荪和花菖蒲对Zn的吸收能力较强,且吸收的重金属主要积累在根系。     

濒危植物矮牡丹种群生物量的研究

对矮牡丹种群生物量的研究表明，矮牡丹地上无性小株的叶、茎干和根系的生物量可分别用m1（DW）＝－0．232＋000771A，ms（DW）＝0．370＋0．18000（D2H1），mr（DW）＝1．54＋0．000338（AH1）来表示象矮牡丹这种似棕榈型生长型的小灌木，植冠面积容易测得，用植冠面积进行叶重的模拟最为准确随年龄的增长，矮牡丹种群各部分生物量都呈指数模式增长     

荔枝胚性愈伤组织体胚发生系统的优化及转化抗性愈伤组织培养再生植株

首先优化了荔枝(Litchi chinensis Sonn.)幼胚胚性愈伤组织(embryogenic calli,EC)体胚发生的条件，在附加5mg L^-1 ZT的高糖(60g L^-1)高琼脂(10g L^-1)的MS培养基上获得了荔枝高频率(100％)体胚发生；同时，对荔枝体胚成熟和成苗的关键问题作了分析，建立了一套完整的荔枝体胚发生与再生系统，在附加10％椰子汁的高糖(6％)MS培养基上诱导体胚正常成熟，并在无激素MS培养基中诱导体胚萌发，为荔枝转基因研究提供了良好的受体系统．利用此再生系统对荔枝转基因抗性愈伤组织进行体胚发生与再生植株研究，获得了大量再生植株．图1表7参11     

Assimilation of dietary free amino acids,peptides and protein in post-larval Atlantic halibut (<Emphasis Type="Italic">Hippoglossus</Emphasis><Emphasis Type="Italic">hippoglossus</Emphasis>)

With the aim of improving the formulation of diets for early stages of marine fish, post-larval Hippoglossus hippoglossus (56 days after first feeding; 23 mg dry weight) were tube-fed liquid diets of radiolabelled L-(¹⁴C) free amino acids (FAA diet), peptides (PEPT diet) and protein (PROT diet), in order to compare the kinetics of transfer from gut into the liver and carcass. The test diets were prepared using equal concentrations of amino acids (AA) and fed as a single pulse (0.3 µl, 2.2 µg AA). The PROT diet consisted of methylated-¹⁴C-labelled (mainly lysine) bovine serum albumin (BSA), the PEPT diet was the PROT diet digested with trypsin and the FAA diet consisted of an amino acid mixture based on BSA composition with added ¹⁴C-lysine. The common labelling with ¹⁴C-lysine permitted a comparison of the three diets. Based on dissection and distribution of the tracer in each compartment, the FAA diet was almost completely absorbed 1 h after the tube-feeding; PEPT and PROT diets required more time before they were processed by the digestive tract. The FAA diet was absorbed about eight times as fast as protein and about six times as fast as peptides from the gut. A low retention of label in the liver for all diets at all sampling times suggests that the liver does not store the AA at these absorption rates. The FAA diet had a higher assimilation efficiency (about 90%) than the PEPT diet (about 12%) and PROT diet (about 32%). FAAs, thus, appear to be superior to protein and peptides as a dietary source of amino acids in post-larval Atlantic halibut.     

Zooplankton biomass in the ice-covered Weddell Sea,Antarctica

Zooplankton was sampled by a Rectangular Midwater Trawl (RMT 1 + 8) in Weddell Sea surface waters (0 to 300 m) between 66 and 78°S during austral summer (February – March 1983). Sixty-nine taxa including different developmental stages were considered and divided into 16 size classes between <1 and >39.5 mm length. Biomass was determined by taxon and size class for three different meso- and macroplankton communities in the oceanic region, on the northeastern shelf and on the southern shelf of the Weddell Sea. The highest biomass of 11.2 mg DW m^–3 (3.4 g DW m^–2) was found in the northeastern shelf community (70 to 74°S), where juvenile and adultEuphausia crystallorophias accounted for 3.7 mg DW m^–3 (1.1 g DW m^–2). Although not quantitatively sampled, early copepodite stages (CI to CIII) ofCalanoides acutus andCalanus propinquus ranked second with 2.7 mg DW m^–3 (0.8 g DW m^–2). Biomass in the northeastern shelf community was concentrated in the size ranges 1 to 4 mm and 19.5 to 39.5 mm. The oceanic community of the central Weddell Sea was dominated by copepods smaller than 5 mm, which made up half of the total oceanic biomass. The tunicateSalpa thompsoni (7.0 to 8.5 mm) was the dominant single species with 1.6 mg DW m^–3 (0.5 g DW m^–2). Euphausiids, mainly juvenile and adult krillEuphausia superba, comprised 1.2 mg DW m^–3 (0.4 g DW m^–2). Total standing stock in the oceanic community was 9.4 mg DWm^–3 (2.8 g DW m^–2). Lowest biomass values were found in the southern shelf community (south of 75°S) with 4.0 mg DW m^–3 (1.2 g DW m^–2), concentrated in the 1 to 4 mm and 14.5 to 34.5 mm size classes. Abundant species were the pteropodLimacina helicina (1 to 2 mm; 0.7 mg DW m^–3; 0.2 g DW m^–2) andE. crystallorophias (24.5 to 39.5 mm; 0.9 mg DW m^–3; 0.3 g DW m^–2). The data reveal that it is essential to distinguish among subsystems in the Southern Ocean. This leads to a better understanding of the structure and function of those pelagic food webs which represent alternatives to the paradigmatic krill-centered system.     

Amino acid uptake and respiration by marine heterotrophs

The concentration and turnover of dissolved free amino acids were measured in samples from 25 and 100 m on three occasions at a station 6 miles off the California (USA) coast. Individual amino acid concentrations varied from undetectable (<0.05 g/l) to 3 g/l, the total amino acid concentration from 1.8 to 8.5 g/l. The greater concentration of total amino acids was always found at 25 m. The predominant amino acids were serine, lysine, aspartate, glutamate and alanine; reliable analyses could not be made for glycine because of a high blank. For the 10 individual amino acids studied, the rate of heterotrophic turnover ranged from undetectable to 1.2 g/l day^-1; serine, aspartate, alanine and glutamate showed the highest rates. In samples from 25 m, the rates were 15 to 20 times higher than those taken from 100 m. The total calculated flux of the amino acids studied varied from 0.015 to 3.2 g/l day^-1 and amounted to 1–10% of photosynthetic carbon dioxide fixation.     

Free amino acids and energy metabolism in eggs and larvae of seabass, Lates calcarifer

Contents of free amino acids (FAA), protein and ammonium ions together with rates of ammonia excretion and oxygen consumption were measured in order to study the role of FAA as an energy substrate in developing eggs and larvae of seabass (Lates calcarifer) maintained in seawater (30 ppt) at 28 °C without feeding. Initially eggs contained 25.3 nmol ind⁻¹ of FAA of which 21.5 nmol was rapidly utilised by the developing eggs and larvae during the period up to 40 h post spawning (PS) when nearly all the yolk had been resorbed. During the same period, a net increase in protein content of 1.7 μg ind⁻¹ was observed, indicating that the major part of the amino acids lost from the free pool had been polymerised into body proteins. Assuming that the balance of the FAA after protein synthesis was used entirely for energy metabolism, FAA appeared to be an important energy substrate during the embryonic stages (2 to 16 h PS); after hatching, the contribution of FAA to energy metabolism was less significant. From 50 h PS until the end of the study period at 100 h PS, amino acids derived from somatic protein were used for energy metabolism. For the overall period from just after spawning up to 100 h PS, the data indicate that ca. 14% of the total aerobic energy metabolism was derived from amino acid catabolism. Received: 26 September 1997 / Accepted: 1 April 1998