木聚糖酶基因xynB在不同大肠杆菌表达系统中的表达比较

从黑曲霉(Aspergillus niger)nl-1中克隆获得木聚糖酶基因xynB.该基因全长745 bp,含有67 bp内含子,与公布的黑曲霉xynB基因有较高的同源性.将PCR扩增的木聚糖酶成熟肽基因和含有信号肽的基因分别连接到表达载体肠杆菌Top10 F’、DH10B和两种BL21宿主中获得重组菌株.通过IPTG诱导,xynB基因在重组菌株中获得特异性表达.表达产物以胞内可溶性蛋白和不溶性包涵体形式存在.诱导4 h,重组菌株pTrc-99a-xynB[BL21 condon plus(DE3)]表达量最高,胞内酶活达到299 IU/L.重组质粒pTrc-99a-xyn B(S)在不同宿主胞内和胞外均能分泌目的蛋白,诱导10 h,胞外酶活pTrc-99a-xynB(S)[BL21 condon plus(DE3)]达到347 IU/L.而pET-20b-xynB(S)在两种BL21宿主中均不表达.经SDS-PAGE分析,以pTrc-99a和pET-20b作为表达载体时,重组蛋白相对分子质量分别约为45×103和30×103.与pET-20b相比,pTrc-99a以及自身信号肽的引导更有利于重组木聚糖酶的表达.     

假单胞菌表达载体pYMB03的构建与性能分析

恶臭假单胞菌(Pseudomonas putida)是具有强抗逆性能的环境优势菌,构建其质粒表达载体有着明显的应用潜力.将恶臭假单胞菌AB92019菌株中肽聚糖相关脂蛋白编码基因的启动子PoprL和质粒载体pTrcHis-B的多克隆位点片段插入到质粒载体pUCPl8的EcoRL/HInIII位点,获得了重组载体pYMB03.用绿色荧光基因gfp作为标记进行外源蛋白表达的结果表明,该载体能分别在恶臭假单胞菌AB92019菌株和大肠杆菌DH5a菌株中,由启动子PoprL启动组成型表达GFP蛋白并使细胞产生可见荧光.经SDS-PAGE验证,所产生的GFP蛋白分别占细胞总蛋白的12.5%和5.O%.重组菌株YMB001中GFP表达量与菌体培养时间有关,在稳定期后期其相对荧光强度达到最大值(D600nm=l.0),但与培养温度未见相父性.对携带该载体的2株重组恶臭假单胞菌7次168 h继代培养测定,载体pYMB03的稳定性均为100%.     

代谢工程改造Escherichia coli生产L-苹果酸

为了高效生产L-苹果酸,首先在大肠杆菌w3110中敲除ldh A、pox B、pfl B和pta-ack A基因积累丙酮酸,为L-苹果酸合成提供前体,并且通过苹果酸酶的引入构建L-苹果酸一步合成路径,将丙酮酸转化为L-苹果酸.在此基础上,敲除frd BC、fum B和fum AC阻断L-苹果酸代谢路径,并结合pos5基因的表达对胞内辅因子路径进行优化.结果表明:(1)ldh A、pox B、pfl B和pta-ack A基因的敲除能有效地提高丙酮酸产量到20.9 g/L;(2)苹果酸酶突变及过量表达使得L-苹果酸和琥珀酸产量分别提高了87.2%和31.6%,达到1.46 g/L和3.25 g/L;(3)通过敲除frd BC、fum B和fum AC,L-苹果酸产量增加到3.42 g/L;(4)pos5基因的表达降低了胞内NADH/NAD+比率,增加了NADPH含量,最终突变菌株Escherichia coli F0921的L-苹果酸产量达到9.34 g/L.因此,通过苹果酸酶构建L-苹果酸生物合成路径提高L-苹果酸的生产是可行的,结果可为代谢工程改造大肠杆菌生产L-苹果酸提供了新的研究思路.     

响应面法优化短小芽孢杆菌SCU11发酵产碱性蛋白酶及关键基因转录调控分析

短小芽孢杆菌SCU11是由本实验室分离的野生菌株BA06经过复合诱变得到的高产碱性蛋白酶菌株,其产生的碱性蛋白酶在生物制革领域具有很好的应用前景.为进一步提高菌株的蛋白酶产量以满足工业生产的需求,本研究利用响应面法优化菌株产蛋白酶的发酵培养条件.在前期单因素实验的基础上,通过Plackett-Burman实验设计、最陡爬坡实验、中心组合实验设计和响应面分析法,确定了当黄豆粉浓度为53.3 g/L,温度为28℃时,蛋白酶活有理论最大值8 884 U/m L,摇瓶实验验证酶活为8 768 U/m L,达到理论预测值的98.7%,比优化前酶活提高了1倍.为了解优化的发酵条件使蛋白酶产量提高的原因,对短小芽孢杆菌蛋白酶基因及相关调控基因的表达情况进行荧光定量PCR分析,结果显示,优化后5种蛋白酶基因的表达量上调,1种表达量下调;5种蛋白酶相关调控基因的表达量增加,2种基因表达量降低.推测是优化后正调控基因表达量的增加以及负调控基因表达量的降低,促进了短小芽孢杆菌胞外蛋白酶基因转录水平的提高,导致胞外蛋白酶产量增加.本研究采用响应面法优化发酵条件使短小芽孢杆菌SCU11蛋白酶产量提高了1倍,并为阐明其表达调控机制奠定了基础.(图3表7参24)     

两种启动子对聚γ-谷氨酸降解酶基因在地衣芽胞杆菌中的加强表达效果

聚γ-谷氨酸(γ-PGA)是一种应用前景良好的生物高分子材料.比较了蔗糖诱导的枯草芽胞杆菌果聚糖蔗糖酶基因(SacB)启动子和地衣芽胞杆菌α-淀粉酶基因启动子对γ-PGA降解酶基因ywtD在地衣芽胞杆菌中加强表达的影响.分别用SacB基因启动子和α-淀粉酶启动子构建了穿梭表达载体pHY300-SYT和pHY300-PYT,通过电转化地衣芽胞杆菌WX-02获得重组子SYT和PYT.酶活测定结果显示SYT和PYT中γ-PGA降解酶基因ywtD得到加强表达,摇瓶发酵结果显示两个重组菌株的γ-PGA相对分子质量都由1 000 000~1 200 000降低为800 000~900 000,PYT的γ-PGA产量较对照菌株PLK提高了33%,由13.50 g L-1提高到17.97 g L-1,而SYT的γ-PGA产量则降低为10.85 g L-1.因此,α-淀粉酶启动子更适合于在地衣芽胞杆菌WX-02菌株中表达γ-PGA降解酶基因,从而获得高产低分子量γ-PGA的工程菌.     

邻苯二酚2,3-双加氧酶基因克隆、定位和高效表达

采用特异性引物，以菲、芘降解菌株ZL5的代谢性质粒为模板，扩增出邻苯二酚2，3—双加氧酶(C23O)基因，将该基因和表达载体pET—30a( )连接，转化E.coli JM109(DE3)，获得了高效表达的转化子，SDS—PAGE结果表明，转化子的C23O蛋白不仅在细胞内存在，而且能被分泌到胞外，薄层扫描显示，转化子细胞内和细胞外表达蛋白总量占细胞总蛋白的42％，酶活分析表明，分布在转化子细胞内、外的表达蛋白都具有较高的C23O比活力，Southern杂交将菌株ZL5的C23O基因定位在内生质粒的不同酶切片段上。图5表1参12。     

运动发酵单胞菌共表达α-淀粉酶和葡萄糖淀粉酶发酵甘薯生产乙醇

运动发酵单胞菌是乙醇发酵的极佳菌种,但其所能利用的发酵底物范围狭窄,不能利用淀粉作为发酵底物.为增加其利用底物的范围使其能够水解淀粉,本研究构建了3种表达淀粉酶的运动发酵单胞菌菌株:1)Zymomonas mobilis(pAmyE)表达α-淀粉酶;2)Z.mobilis(pGA)表达葡萄糖淀粉酶;3)Z.mobilis(pAmyGA)共同表达α-淀粉酶和葡萄糖淀粉酶.DNS法测定淀粉酶活显示,每种转化菌株的胞外淀粉酶活性均高于胞内,且两种淀粉酶共表达的酶活高于这两种淀粉酶单独表达的酶活之和,说明这两种淀粉酶能够协同作用降解淀粉.对于重组菌株Z.mobilis(pAmyGA),约59.3%的淀粉酶活性都在胞外检测到.用淀粉含量高且耐贮存的徐薯18匀浆加少量葡萄糖作为培养基直接用上述3个菌株发酵生产乙醇.结果显示,共表达α-淀粉酶和葡萄糖淀粉酶的重组菌株Z.mobilis(pAmyGA)的乙醇产量为54.7 g/L,达到了理论值的83.2%,表明本研究得到了能够直接高效利用淀粉生产乙醇的运动发酵单胞菌的菌株.     

粘红酵母△12-脂肪酸脱氢酶基因的克隆和表达

Δ12-脂肪酸脱氢酶一般特异性催化在油酸的Δ12位引入双键转变成亚油酸.为了从粘红酵母YM25079中克隆全长Δ12-脂肪酸脱氢酶基因序列,参考已知的Δ12-脂肪酸脱氢酶基因序列设计基因特异性引物,通过PCR扩增获得到全长为1 353 bp的c DNA序列,序列分析结果表明该序列具有一个编码450个氨基酸的完整开放阅读框,所编码蛋白质的大小为50.9×103.与报道的Δ12-脂肪酸脱氢酶一样,推测的氨基酸序列具有膜整合脂肪酸脱氢酶特异性的3个组氨酸保守区,表明该序列为一个新的编码Δ12-脂肪酸脱氢酶的基因.为了验证其功能,把开放阅读框序列亚克隆到表达载体p YES3/CT,构建重组表达载体p YRGD12,并转化到酿酒酵母的缺陷型菌株INVScl进行表达.脂肪酸气相色谱(GC)分析表明,该序列所编码的蛋白质具有Δ12-脂肪酸脱氢酶活性,能将油酸转化为亚油酸,亚油酸的含量占酵母总脂肪酸的4.31%.以上结果表明,PCR所获得序列是新的Δ12-脂肪酸脱氢酶基因.     

碱性果胶酯裂解酶工程菌的构建

从本研究室筛选的BacillussubtilisWSHB04-02菌株中扩增出编码碱性果胶酯裂解酶的结构基因PL,将其插入大肠杆菌分泌表达载体pET22b( )多克隆位点,得到重组载体pET22b( )PL.序列分析表明,所获PL基因与已报道的B.subtilisSO113的PL基因的同源性为98%.重组载体在大肠杆菌BL21(DE3)中得到表达.SDS-PAGE分析显示,表达产物的分子量(Mr)均为43×103,同核酸序列测定所推导的值相符.该工程菌经IPTG诱导后,胞内酶活为8U/mL.研究发现,碱性果胶酯裂解酶不仅在胞内有酶活,胞外也有酶活,说明所构建的表达体系可使该酶向胞外分泌.图3表1参6     

一株产胞外多糖的山药内生细菌Lysinibacillus fusiformis S-1的分离和鉴定

微生物的胞外多糖是重要的生物资源,为获得新型的具有药用价值的胞外多糖产生菌,从山药、地瓜、马铃薯和胡萝卜的根茎组织中分离、筛选到11株能产胞外多糖的植物内生菌,利用苯酚–硫酸法对这11株菌的多糖产量进行了定量分析.对多糖产量最高的S-1菌株,检测其在发酵过程中菌体生长、胞外多糖生成以及发酵过程的pH变化,绘制其胞外多糖发酵代谢曲线.通过形态观察、培养特性观察、生理生化实验和16S rDNA序列分析对该菌株进行了鉴定.结果显示,S-1菌株在产糖培养基中可以产生1.50 g/L的胞外多糖,在11株菌中产量最高.16S rDNA序列分析显示该菌属于赖氨酸芽孢杆菌(Lysinibacillus),且与纺锤形赖氨酸芽孢杆菌(L.fusiformis)亲缘最近.综合其形态特征、培养特性和生理生化实验结果,将S-1菌株鉴定为纺锤形赖氨酸芽孢杆菌.该菌在胞外多糖产生菌中少有报道,为胞外多糖的进一步研究提供了菌种资源.     

Studies on the lipid metabolism of some oceanic crustaceans

Mid-water, oceanic crustaceans were either fed food labelled with (¹⁴C) palmitic acid under controlled conditions, or injected directly with (¹⁴C) palmitic acid. Lipid classes and their constituent fatty acids and fatty alcohols were subsequently separated and assayed for radioactivity. Significant levels of radioactivity were present in the 16:0¹ alcohols and 18:1 acids of wax esters, and in the 16:0/16:1, 18:0/18:1, 20:5 and 22:6 acids of both triglycerides and phospholipids. It was concluded that these crustaceans were capable of biosynthesis of wax esters and higher polyunsaturated fatty acids.     

Changes in phospholipase A2 activity and lipid content during early development of Atlantic halibut (Hippoglossus hippoglossus)

During early development in fish, phospholipase A₂ (EC 3.1.1.4) regulates membrane lipid modifications, which relates to changes in environmental conditions and provision of fatty acids required for metabolic energy substrates and prostaglandin biosynthesis. A method to analyze phospholipase A₂ in rat tissues has been modified to measure its activity in embryonic Atlantic halibut (Hippoglossus hippoglossus L.). Egg and embryo samples were collected during the 1994 spawning season. Enzyme activity was undetectable at fertilization but in 10-d embryos was 230 pmol mg⁻¹ h⁻¹ (at 20 °C) and increased by ∼120% at hatch (17-d). Significant alterations in the fatty acid composition of important phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), were also observed. The content of some critical polyunsaturated fatty acids, and the ratio of unsaturated/saturated fatty acids, declined significantly over development. Acyl-chain restructuring mediated through the activity of phospholipase A₂, coupled with other observed lipid changes (significant increases in the PC/PE ratio and cholesterol content), would produce a decreased fluidity of membranes during embryonic development, coinciding with the predicted upward movement of larvae in the water column. Arachidonic acid (20:4n-6) removed from PE could serve as a precursor for biosynthesis of 2-series prostaglandins, and eicosapentaenoic acid (20:5n-3) from PC is a likely source for other prostaglandin types. Despite removal of polyunsaturated fatty acids, there was an overall increase in lipid and fatty acid concentration, which can be attributed to amino acid catabolism during early developmental stages. Received: 9 September 1996 / Accepted: 8 September 1997     

Seasonal patterns in fatty acids of <Emphasis Type="Italic">Calanus hyperboreus</Emphasis> (Copepoda,Calanoida) from Cumberland Sound,Baffin Island,Nunavut

The marine copepod Calanus hyperboreus accumulates large quantities of lipids and essential fatty acids during summer months in Northern oceans. However, few data exist regarding their winter fatty acid profiles, which could be informative regarding the use of lipids by C. hyperboreus to successfully survive and reproduce during times of ice-cover and limited food. The present study compared fatty acids of C. hyperboreus between summer (August 2007 and 2008) and winter (early April 2008 and 2009) in Cumberland Sound, Canada. Summer samples from both years had significantly higher ∑polyunsaturated fatty acids and unsaturation indices (based on μg fatty acid mg dry tissue⁻¹) than winter samples and separated on a principal component analysis due to higher 18:2n-6, 18:4n-3, and 20:5n-3, consistent with phytoplankton consumption. Winter C. hyperboreus had significantly higher ∑monounsaturated fatty acids (MUFA) versus summer samples and separated on the principal component analysis due to higher proportions of 16:1n-7, 20:1n-9, and 22:1n-9, suggesting they were not actively feeding. Based on the seasonal fatty acid comparison, C. hyperboreus was catabolizing specific fatty acids (e.g. 20:5n-3), conserving others (e.g. 22:6n-3), and maintaining or increasing biosynthesis of certain MUFA (e.g. 18:1n-9) during winter. These findings provide insight into the seasonal strategy of acquisition (summer) and utilization (winter) of specific fatty acids by a key Arctic organism and could become important for monitoring changes in fatty acids associated with decreased ice-cover duration due to climate warming.     

Lipid composition and partitioning of deepwater chondrichthyans: inferences of feeding ecology and distribution

The composition of lipids and fatty acids was determined for the livers, muscle, pancreas, kidney and stomach fluids of deepwater chondrichthyan species (including 11 squaliformes, 3 chimaeriformes, 1 hexanchiforme and 3 carcharhiniformes) caught as bycatch from continental waters off south-eastern Australia. The lipid class, fatty acid and fatty alcohol composition differed markedly in each tissue and in each species. The lipid and fatty acid composition of large, lipid-rich (38–70% wet weight, ww) livers demonstrated the multifunctional role of this organ in: lipid distribution, storage and biosynthesis, and buoyancy regulation. In the liver, the importance of certain lipids (including squalene, diacylglyceryl ethers, triacylglycerols and to a lesser extent wax esters) as mediators of buoyancy varied according to lifestyle and habitat. Less variability was observed in the muscle profiles, characterized by low lipid content (<1.0% ww) and high relative levels of polar lipids (>70%). The lipid and fatty acid profiles of the kidney and pancreas showed the highest intraspecific variability, suggesting these organs also have complex roles in lipid storage and metabolism. Overall intra- and interspecific differences in the tissue fatty acid profiles could be related to differences in a number of factors including phylogeny, habitat (depth), buoyancy regulation and diet and presumably also reflect different ecological roles. The lipid and fatty acid profiles are the first published for Rhinochimaera pacifica, Chimaera lignaria and Figaro boardmani and the first to demonstrate interspecific variation in lipid profiles of various tissues of deepwater chondrichthyans. The application of multivariate analysis to lipid class and fatty acid tissue profiles in chondrichthyans inferred dietary differences and metabolic preferences between species and habitats. These results have important implications for the future use of fatty acids as dietary tracers in chondrichthyan research.     

Sources and major biogeochemical pathways of organic matter in the mangrove system of Rufiji estuary

Fatty acids were extracted from the surface sediments (10 cm) of three sampling sites of Rufiji estuary to infer their sources and biogeochemical pathways. The fatty acids ranging from C₈ to C₂₄ were distinguished from this study, and were broadly classified into saturated (SFAs), monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs). SFAs were found to be the major fraction at station 1 and 3 where as at station 2, MUFAs dominated. A total of 19 fatty acids with a total concentration of 64.91 μg/g dry weight were characterised at station 1. C_16:0 was the most abundant fatty acid contributing 21.94% of total fatty acids (TFAs). C_22:2 was the second most abundant, which accounted for 9.46% of TFAs. Fatty acids ranging from C₁₂ to C₂₄ were identified at station 2. C₂₀ fatty acid was the most abundant fatty acid contributing 21.94%, followed by C_16:0. At station 3, fatty acids ranging from C₈ to C₂₄ were obtained. The PUFA C_20:5n-3 was the most abundant fatty acid contributing 21.65%, followed by C_24:0 (15.00% of TFAs). The ratio of lower molecular weight (LMW) to higher molecular weight (HMW) biomarkers was used as an indicators to distinguish higher plants organic matter from algae-derived fatty acids.     

Acetate incorporation into the lipids of the anemone Anthopleura elegantissima and its associated zooxanthellae

Anthopleura elegantissima containing zooxanthellae, as well as isolated zooxanthellae, incubated with acetate-1-¹⁴C under both light and dark conditions readily incorporate radioactivity into their total lipid pools. In both cases, the specific activity was greatly increased in the light. Dark-incubated anemones and isolated zooxanthellae incorporate activity predominantly into polar lipid; the remainder being present principally in the triglyceride moiety. Light-incubated organisms, however, show a dramatic redistribution of isotope towards greatly increased triglyceride and was ester incorporation, with a concomitant drop in polar lipid. onder light conditions, 70 to 75% of the radioactivity found in the fatty acids of the total zooxanthellae lipid was present in hexadecanoic (16:0) and octadecenoic (18:1) fatty acids. These are also the two major fatty acids by mass. Octadecanoic acid (18:0) is less than 5% by mass. Isotope incorporation patterns suggest that octadecenoic acids arise by elongation of hexadecenoic acids and that this conversion is blocked in the dark. Isotope incorporation patterns for anemones suggest that fatty acids, primarily in the form of saturated or monoenoic fatty acids, are translocated from algal to animal cells. No activity was found in either octadecadienoic (18:2) or octadecatrienoic (18:3) acids. The significance of these data is discussed.     

Energy substrates for eggs and prefeeding larvae of the dolphinCoryphaena hippurus

Changes in the chemical composition of developing dolphin (Coryphaena hippurus) eggs and prefeeding yolksac larvae were determined in order to estimate probable dietary requirements of first-feeding larvae. Daily dry matter, protein nitrogen (PN), non-protein nitrogen (NPN), lipid, gross energy content, fatty acid and amino acid profiles from Day 1 to Day 2 eggs and Day 1 to Day 3 larvae were compared. Lipid was the primary endogenous energy source accounting for the daily caloric deficit through both the egg and larval stages, except over the day of hatching. The catabolism of lipid by embryos (0.078 cal d^–1) was greater than that by yolksac larvae (0.036 cal d^–1). The higher demand for energy by embryos was related to a greater rate of protein synthesis during the egg stage. The ratio of PN:NPN increased during egg development without change in total nitrogen content, but was constant throughout the yolksac larvae period. The lipid content per embryo did not decrease over the hatching period (Day 2 to 3, postspawning). However, there was a loss in amino acid content not totally accounted for by sloughing of the chorion at hatching. This loss, as protein, accounted for 0.053 cal of gross energy, which represented 70% of the total estimated energy needs of the fish over this period. Loss of non-essential amino acids (25%) was higher than that of essential amino acids (13%). Proline and tyrosine accounted for 32% of the total loss of amino acids at this time. The only preferential use of fatty acids over any period was a small but significant drop in the content of C22:6n-3 prior to the onset of feeding (Day 5, postspawning). It is speculated that the pattern of energy-substrate use of first-feeding dolphin larvae will reflect the pattern of endogenous energy use during the egg and prefeeding yolksac larval stages. Diets or feeding regimens with lipid as the primary energy source, and containing a fatty acid profile similar to that of eggs or yolksac larvae, should be useful in culturing this species, at least during the early feeding stages.     

Variations saisonnières de la composition en acides gras chez Penaeus japonicus (Crustacea: Decapoda)

The lipid and fatty acid composition of male and female Penaeus japonicus Bate was investigated over a period of 11 months to determine the effects of environmental and nutritional factors such as temperature and starvation. The lipid content of the prawns increases from May to November, whereas water content decreases. We observed a time-lag between the highest lipid rate of males (in November) and that of females (in October); this is probably related to ovarian metabolism. From September to March, the high lipid content of the females coincided with a high percentage of monounsaturated fatty acids (especially 16:1 and 18:1). Winter starvation induces a decrease in palmitic acid content. As temperature decreases, the monounsaturated (16:1, 18:1) and polyunsaturated (20:4, 20:5, 22:6) fatty acids increase at the expense of the saturated fatty acids (16:0, 18:0) in the adult prawn. However, in post-larvae and juveniles, this increased rate of polyunsaturated fatty acids would be related to their particular lipid metabolism.     

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.     

Biosynthesis of lipds in zooplankton from Saanich Inlet,British Columbia,Canada

Lipid analyses were carried out on various species of zooplankton captured in Saanich Inlet, British Columbia, Canada, during September, 1972. The amphipod Cyphocaris challengeri had the highest level of lipid, consisting mainly of wax esters. The copepod Calanus pacificus had moderate amounts of lipid, with triglyceride as the major neutral lipid. The euphausiid Thysanoessa raschii contained mainly triglyceride in its moderate levels of neutral lipid, while wax esters and, to a lesser extent, triglycerides were present in the very small levels of neutral lipid in the chaetognath Sagitta elegans. The major fatty alcohols in wax esters of both Cyphocaris challengeri and Calanus pacificus were 20:1 and 22:1, although notable differences were found in the major fatty acids. Biosynthetic studies showed that phospholipids were labelled faster than neutral lipids in all species with both (U-¹⁴C) glucose and (1-¹⁴C) palmitic acid as precursors. Only species containing significant amounts of wax esters in their neutral lipids incorporated substantial amounts of radio-activity from (1-¹⁴C) palmitic acid into wax esters in (i) living animals, (ii) preparations containing fragments of tissue, (iii) cell-free systems. All species incorporated added fatty alcohols into wax esters in preparations containing tissue fragments and in cell-free preparations. Both the fatty acid and fatty alcohols of the wax esters of both Calanus pacificus and S. elegans were labelled from (1-¹⁴C) palmitic acid, consistent with de novo biosynthesis of the esters. (1-¹⁴C) hexadecanol was incorporated into wax esters almost entirely in the fatty alcohol moiety. It is concluded that all species examined formed was esters when presented with preformed fatty alcohols, but only those species that had wax esters as a major component of the neutral lipids were capable of de novo biosynthesis of the lipids.