ALA Content Research Articles

Fatty acids profile in Carassius spp. From Lake Gopło, Poland

Effects of sex and age on fatty acids profile in the meat of Carassius spp. were evaluated. Carassius auratus fillets displayed a higher content of SFA and MUFA than Carassius carassius. In contrast, Carassius carassius had a higher content of PUFA (higher proportion of linoleic, arachidonic, eicosapentaenoic, docosatetraenoic and docosapentaenoic acids) and total n-3 and n-6 PUFA, compared with Carassius auratus. Moreover, Y-linolenic acid was higher in fillets from Carassius auratus. What is more, fillets from females had a greater content of eicosapentaenoic acid than males. Finally, 4-year-old fish had a lower content of ALA, higher MUFA content and better nutritional indexes (n-3/n-6, AI) than 3-year-old fish.

A Novel Dietary Source of EPA and DHA: Metabolic Engineering of an Important Freshwater Species—Common Carp by fat1-Transgenesis

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), such as eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA), are essential for neural development and human health. The n-3 PUFAs are mainly obtained from marine fish by dietary intake. Freshwater fish species usually contain low level of n-3 PUFAs due to the lack of n-3 PUFAs in their food chain. In this study, we report on the substantial production of EPA and DHA in a globally important freshwater fish species, common carp (Cyprinus carpio). This was achieved by introducing an "all-fish" transgene CA:fat1 containing the fish codon-optimized omega-3 desaturase gene (fat1) driven by the common carp β-actin promoter (CA). Through a sperm sample screening method, we successfully generated fat1-positive F1 transgenic population with high efficiency. In F1 population, the muscle contents of ALA (18:3n-3), EPA and DHA were significantly increased when compared with non-transgenic siblings. Thereafter, four independent F2 heterozygous lines were obtained from 4 F1 transgenic males and a detailed comparison of fatty acids profile and growth performance was carried out for these 4 lines. All fat1-transgenic common carps from 4 lines showed an evident decrease in n-6 PUFA contents and a substantial increase in n-3 PUFA contents, among which line 4 stands out, showing a statistically significant increase in all 4 types of n-3 PUFAs including ALA (4.4-fold increase, p < 0.001), EPA (4.8-fold increase, p < 0.01), C22:5n-3 (DPA, 2.4-fold increase, p < 0.05), and DHA (1.9-fold increase, p < 0.05). Therefore, the line 4 was selected as the optimized breeding stock for further study, and the proximate nutrition composition and PUFA synthesis pathway were analyzed. Our study demonstrates that in the transgenic group, the muscular lipid content did not change, while fat accumulations in the internal organs and especially in the liver were significantly decreased as a result of hyperactivation of fatty acid oxidation process. Finally, we conclude that the "all-fish" CA:fat1-transgenic freshwater fish-common carp-can serve as a novel healthy dietary source of n3-PUFAs, especially EPA and DHA.

Comparative Transcriptome Analysis Reveals an Efficient Mechanism of α-Linolenic Acid in Tree Peony Seeds.

Tree peony (Paeonia section Moutan DC.) species are woody oil crops with high unsaturated fatty acid content, including α-linolenic acid (ALA/18:3; >40% of the total fatty acid). Comparative transcriptome analyses were carried out to uncover the underlying mechanisms responsible for high and low ALA content in the developing seeds of P. rockii and P. lutea, respectively. Expression analysis of acyl lipid metabolism genes revealed upregulation of select genes involved in plastidial fatty acid synthesis, acyl editing, desaturation, and triacylglycerol assembly in seeds of P. rockii relative to P. lutea. Also, in association with ALA content in seeds, transcript levels for fatty acid desaturases (SAD, FAD2, and FAD3), which encode enzymes necessary for polyunsaturated fatty acid synthesis, were higher in P. rockii compared to P. lutea. Furthermore, the overexpression of PrFAD2 and PrFAD3 in Arabidopsis increased linoleic and ALA content, respectively, and modulated the final ratio 18:2/18:3 in the seed oil. In conclusion, we identified the key steps and validated the necessary desaturases that contribute to efficient ALA synthesis in a woody oil crop. Together, these results will aid to increase essential fatty acid content in seeds of tree peonies and other crops of agronomic interest.

Effects of dietary n‐3 PUFA supplements on composition of n‐3 PUFA and expression of fatty acid elongase 5 (AJELOVL5) in sea cucumber, Apostichopus japonicus

This is the first comprehensive study on the effect of dietary polyunsaturated fatty acid (PUFA) levels on the expression of fatty acid elongase 5 (AJELOVL5), PUFA composition, and growth in juvenile sea cucumbers. The specific growth rate (SGRw) was improved in n-3 PUFA-rich diets compared to low n-3 PUFA diets. AJELOVL5 expression was apparently upregulated in juveniles fed lower PUFA diets relative to higher PUFA diets, with higher expression in the body wall and respiratory tree of juveniles fed diets without ɑ-linolenic acid (ALA, 18:3n-3) compared to juveniles fed higher ALA level diets; similar results were also detected in juveniles fed diets with lower eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), and none of ALA, EPA, or DHA respectively. The concentrations of ALA, EPA, and DHA in tissues were positively related to the content of dietary corresponding PUFA, with higher ALA content in juveniles fed diet ALA12.71 than in the ALA7.46 and ALA0 groups. Similar results were also obtained in sea cucumber fed diets enriched with either EPA or DHA. Interestingly, considerable levels of EPA and DHA were found in the tissues of juveniles fed diets of CK0 and DHA0, with no specific input of EPA or DHA, showing that the sea cucumber was capable of biosynthesizing EPA and DHA from their corresponding precursors as ALA and linoleic acid (LA, 18:2n-6).

Influence of pollen sources on the expression of FA and TAG biosynthetic pathway genes in seeds of Paeonia rockii during the rapid oil accumulation

Tree peony has been widely planted as an excellent oil crop with high proportion of α-linolenic acid (ALA) in its seeds. It was reported that pollen sources have clear effects on fatty acid (FA) composition of its kernels. Nevertheless, the molecular basis of this novel phenomenon is poorly understood. In this study, four Paeonia suffruticosa cultivars whose pollen caused significant differences in ALA content of Paeonia rockii were selected as pollen donors and grouped under high and low ALA groups. After pollination, total FAs content, composition and expression profiles of 10 genes involved in the FA and triacylglycerol (TAG) biosynthetic pathways were investigated during seed development. During the rapid oil accumulation in seeds, three desaturase genes (SAD, FAD2, FAD3) showed much higher expression in high ALA group, and their differential expression profiles corresponded well with the variations in ALA content among different pollen sources. Overall, pollen sources could affect the expression level of genes associated with fatty acid modification and subsequently affect the composition of FA in the kernels.

Production of α-linolenic acid in Yarrowia lipolytica using low-temperature fermentation

α-Linolenic acid (ALA) is an essential ω-3 fatty with reported health benefits. However, this molecule is naturally found in plants such as flaxseed and canola which currently limits production. Here, we demonstrate the potential to sustainably produce ALA using the oleaginous yeast Yarrowia lipolytica. Through the use of a recently identified Δ12-15 desaturase (Rk Δ12-15), we were able to enable production in Y. lipolytica. When combined with a previously engineered lipid-overproducing strain with high precursor availability, further improvements of ALA production were achieved. Finally, the cultivation of this strain at lower temperatures significantly increased ALA content, with cells fermented at 20°C accumulating nearly 30% ALA of the total lipids in this cell. This low-temperature fermentation represents improved ALA titer up to 3.2-fold compared to standard growth conditions. Scale-up into a fed-batch bioreactor produced ALA at 1.4g/L, representing the highest published titer of this ω-3 fatty acid in a yeast host.

Detection of QTL underlying seed quality components in soybean [Glycine max (L.) Merr.

Improving seed composition and quality, including protein, oil, fatty acid, and amino acid contents, is an important goal of soybean farmers and breeders. The aim of this study was to map the quantitative trait loci (QTL) underlying the contents of protein, oil, fatty acids, and amino acids with 1510 single nucleotide polymorphism (SNP) markers using the ‘Hamilton’ × ‘Spencer’ recombinant inbred line population (H × S; n = 93). A total of 13 QTL for the traits studied have been mapped on 3 chromosomes (Chr.) of the soybean genome. Three major QTL have been mapped to a 7–13 cM region on Chr. 6. One major QTL for oil content (qOIL001) explained approximately 76% of the total phenotypic variation in this population; the second major QTL for amino acid alanine (Ala; qALA001) explained approximately 74% of the total variation in Ala content; moreover, two major QTL for palmitic acid (qPAL001 and qPAL002) were identified on Chr. 6 and explained approximately 21% of the phenotypic variation in this population. The SNP markers flanking the QTL identified here will be very useful for soybean breeders to develop and select soybean lines with higher seed composition qualities using marker-assisted selection.

The effect of feeding with hemp and Camelina cakes on the fatty acid profile of duck muscles

Abstract. Camelina (Camelina sativa L. Crantz) and hemp (Cannabis sativa L.) seed cakes are rich sources of n-3 polyunsaturated fatty acids (PUFAs). This study was carried out to investigate the effects of Camelina and hempseed cakes in the diet of ducks on the intramuscular fatty acid profile. Male ducks (n = 99) were randomly allocated to 3 dietary treatments: Control or C group (wheat–soybean-meal–barley-based diet with 15–20 % rapeseed cake), Experimental 1 or HEM group (with hempseed cake added at 15–20 % instead of rapeseed cake), and Experimental 2 or CAM group (with Camelina cake added at 15–20 % instead of rapeseed cake). All groups received the diets ad libitum. At 49 days of age, six ducks from each group were slaughtered for analysis of the fatty acid composition in the breast and leg muscles. Feeding ducks with the diet enriched with Camelina cake resulted in significantly higher amounts of n-3 α-linolenic fatty acid (ALA) (P≤0.01) and total n-3 PUFA (P≤0.01) in breast and leg muscles, while eicosatrienoic fatty acid (ETE) (P≤ 0.01) was higher in the leg muscle. The ratios of n-6 ∕ n-3 and linoleic ∕ α-linolenic fatty acids (P≤ 0.01) decreased significantly compared to the Control and HEM groups of ducks. Feeding ducks with the diet enriched with hempseed cake resulted in significantly higher amounts of linoleic (LA) (P≤ 0.01), total n-6 PUFA (P≤ 0.05–P≤ 0.01) and n-6 γ-linolenic (GLA) (P≤ 0.01) fatty acid. Our study showed that using Camelina cake as supplementation in duck diets opens a possibility to develop functional food, i.e. meat with a significantly higher content of ALA, total n-3 PUFA and the lowest ratios of n-6 ∕ n-3 fatty acids in ducks' muscles. A duck diet with hempseed cake produces exceptional-quality meat with an enriched content of n-6 GLA.

Isolation of a novel strain of Monoraphidium sp. and characterization of its potential for α-linolenic acid and biodiesel production

α-Linolenic acid (ALA) is an essential fatty acid which cannot be synthesized de novo in mammals and must be ingested regularly in the diet. In this study, a microalgal strain named HDMA-11 was isolated from Lake Ming, China, and was found to accumulate a high ALA content (39.2% of total lipids). Phylogenetic neighbor-joining analysis indicated that HDMA-11 belongs to the genus Monoraphidium (Selenastraceae, Sphaeropleales) and its 18S ribosomal DNA sequence seemed to be a new molecular record of a Monoraphidium species. The fatty acid profiles, biomass productivity and lipid content of HDMA-11 were also investigated in autotrophic conditions. The high levels of polyunsaturated fatty acids in HDMA-11, especially ALA, make it suitable as a source of nutritional supplementation for human health. Furthermore, HDMA-11 exhibited good properties for biodiesel production, characterized by high lipid content (28.5% of dry weight), moderate biomass productivity (31.5 mg L−1 day−1) and a promising lipid profile.

Effects of diets containing hemp seeds or hemp cake on fatty acid composition and oxidative stability of sheep milk

High levels of polyunsaturated fatty acids (PUFAs) are desirable in milk for its nutritional quality, but make it vulnerable to oxidation. The aim of this trial was to assess the effects of dietary intake of hemp (seeds or cake) on milk production, fatty acid (FA) profile, and oxidative stability when sheep diet included a source rich in PUFAs. The control diet (C), which was composed of hay-based rations and completed with mixed concentrate, was compared with two experimental diets that were designed to provide the same amount of fat via hemp seed (180 g/d) (HS diet) or hempseed cake (480 g/d) (HC diet). The hemp was determined to have significantly increased the yields of milk, energy-corrected milk (ECM), fat corrected milk (FCM) (6.5%), protein corrected milk (PCM) (5.8%) and milk fat. The hemp generated a greater proportion of n-3 FA, notably α-linolenic acid (ALA), which increased by 49–66%. The addition of hemp also led to an increase in C18:1 t 11 (vaccenic acid (VA)) and conjugated linoleic acids (CLA), particularly isomer c 9, t 11 CLA (rumenic acid (RA)). The HC group showed a greater content of milk ALA and VA and tended to show a greater content of c 9, t 11 CLA than the HS group. The atherogenic index (AI), thrombogenic index (TI), n-6/n-3 FA ratio and hypocholesterolemic/Hypercholesterolemic (h/H) ratio suggest that hemp could be useful in improving milk quality. The results obtained in this study suggest that the inclusion of hempseed cake appears to be more effective in ameliorating these indices than hemp seed. The author determined the concentration of fat-soluble antioxidant (tocopherol and retinol) by high performance liquid chromatography (HPLC), and assessed the total antioxidant capacity (TAC) by measuring the ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid) scavenging capacity and degree of oxidative degradation of lipids – using the classical test based on the concentration of malondialdehyde (MDA). The TAC was higher in the milk of the HS and HC groups compared with C, being in direct correlation with the higher concentration of α-tocopherol of milk and lower concentration of MDA, the extent of the change being greatest for the animals fed the HS diet. Therefore, hemp seeds and hempseed cake appear to be ideal supplements for improving the FA profile and health lipid indices and preventing lipid oxidation in raw milk. Keywords: α-linolenic acid, α-tocopherol, antioxidant activity, atherogenicity index, malondialdehyde

Fatty acid desaturase 3 (PsFAD3) from Paeonia suffruticosa reveals high α-linolenic acid accumulation

α-linolenic acid (ALA) deficiency and a skewed ω6: ω3 fatty acid ratio in the diet are thought to be a major cause for the high incidence of cardiovascular, inflammatory, and autoimmune diseases. Recent years, tree peony (Paeonia suffruticosa Andr.) with the high proportion of ALA (more than 45% in seed oil) is widely concerned. However, the underlying accumulation mechanism of the ALA in tree peony seeds remains unknown. In this study, comparative transcriptome analysis was performed between two cultivars (‘Saiguifei’ and ‘Jingshenhuanfa’) with different ALA contents. The analysis of the metabolic enzymes associated with ALA biosynthesis and temporal accumulation patterns of unsaturated fatty acids demonstrated the importance of microsomal ω-3 fatty acid desaturase 3 (FAD3). Moreover, PsFAD3 gene was identified from tree peony seeds, which was located in endoplasmic reticulum and the expression levels of PsFAD3 were consistent with ALA accumulation patterns in seeds. Heterologous expression in Saccharomyces cerevisiae and Arabidopsis thaliana confirmed that the isolated PsFAD3 protein could catalyze ALA synthesis. These results indicated that PsFAD3 was involved in the synthesis of ALA in seeds and could be exploited by the genetic breeding of new cultivars with high ALA content in tree peony as well as other potential crops.

Process optimization and oxidative stability of omega-3 ice cream fortified with flaxseed oil microcapsules.

Microencapsulated flaxseed oil powder (MFOP) was supplemented for the fortification of α-linolenic acid (ALA, ω-3 fatty acid) in ice cream. Processing parameters were optimized in terms of the stage of homogenization of ice-cream mix, level of fortification (3, 4 and 5%) and flavors (vanilla, butter scotch and strawberry). Data revealed that free fatty acids increased significantly during first 15days in all the samples and then remained constant. Peroxide value and thiobarbituric acid value first increased up to 30 and 45days, respectively; and then decreased followed by a gradual increase up to 120days. Fatty acids profile showed 18.74-21.38% decrease in ALA content in fortified ice creams after 120days. A serving of 100g of freshly prepared functional ice cream was able to meet ~45% of the RDA (1.4g ALA/day), which reduced to 35.37-36.56% on the end of storage i.e. 120days. Overall, it can be concluded that MFOP was oxidative stable in ice-cream throughout the storage, which could be fortified successfully at 4% (w/w) level.

Effects of perilla frutescens seed supplemented to diet on fatty acid composition and lipogenic gene expression in muscle and liver of Hu lambs

The objective of this study was to determine the effect of perilla (perilla frutescens L.) seed (PFS) supplementation on serum lipids metabolism, intramuscular adipocyte size, fatty acid composition and lipogenic genes expression in muscle and liver of Hu lambs. Sixty male Hu lambs (23.02 ± 1.36 kg body weight and approximately 3 months of age) were randomly assigned to four dietary treatments receiving diets containing 0%, 5%, 10% or 15% perilla seed (CD, 5%PFSD, 10%PFSD and 15%PFSD, respectively). During the 84 days experimental period, these groups were fed the assigned diets ad libitum. Compared with CD group, LDL-cholesterol, total cholesterol, and triglyceride levels in the serum significantly (P < 0.05) increased with the supplementation of PFS to lamb diets. The supplementation of PFS promote intramuscular adipocyte hypertrophy (P < 0.05). Adding PFS rich in α-linolenic acid (ALA) increased the contents of ALA, vaccenic acid (VA), eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA), in longissimus muscle and liver (P < 0.05). However, the contents of C18:1cis9, linoleic acid (LA), and total saturated fatty acids (SFA) and n-6 to n-3 ratio decreased in muscle and liver in PFS groups compared with CD group (P < 0.05). The supplementation of PFS significantly increased PPARα and PPARγ expression and significantly decreased LPL, ACC, FASN, SCD, FADS1, and FADS2 expression (P < 0.05). These results suggest that PFS supplementation in lambs’ diets can influence the metabolism of lipids and promotes intramuscular adipocyte hypertrophy and deposition of n-3 polyunsaturated fatty acids (n-3 PUFA) in muscle and live tissues.

Impact of production season on the chemical composition and health properties of goat milk and rennet cheese

This study compared selected parameters of milk and rennet cheese produced from milk obtained from alpine goats during winter and summer feeding under climatic conditions of the Warmia and Mazury region. Milk from the winter season contained more protein, less vitamin A and over seven times less vitamin E than milk obtained in summer. In cheese from the winter season, the content of dry matter, fat, protein and vitamin A was lower when compared with cheese from the summer period. The content of total biogenic amines in cheese was almost twice as high in winter than in summer (1056.4 vs 567.6 mg/kg). Winter cheese contained more cadaverines and histamine than summer cheese. The content of tyramine and putrescine was comparable in cheese from both seasons and was higher than the level of histamine. Milk fat from milk obtained in winter contained more long-chained SFA and MUFA in comparison with the summer period. Fat from cheese produced in summer had a higher content of SFA, CLA and ALA, whereas cheese from the period of winter feeding contained more C16:0izo and C18:1. The content of hyper- and hypocholesterolemnic acids was comparable in milk and in cheese with a slightly smaller proportion of hyper-acids and a slightly higher proportion of hypocholesterolemnic acids during summer feeding of goats. In conclusion, it was found that the feeding season had a minor impact on the chemical composition of milk, although it significantly differentiated the chemical composition of rennet cheese produced from that milk and the health quality parameters of both products. Milk from winter feeding had a higher content of protein, whereas the chemical composition of cheese was more beneficial in winter as the content of dry matter, fat and protein was higher. The health properties of both products were more beneficial in summer, which was determined by the profile of fatty acids and the content of vitamin A.

Fatty Acids Decrease in Pearl Millet Forage from Relative Increases of Pseudostem

Core Ideas Fatty acid content and composition of lamina and pseudostem are markedly different. Whole plant fatty acid analysis is a non‐ideal presentation for warm‐season annuals. Lamina mass ratio is an important correlate of fatty acids in warm‐season annuals. Managing for greater lamina intake may greatly influence animal fatty acid supply. Forage fatty acids (FA) are linked with consumer‐desired FA composition of ruminant meat and dairy products. Maturing forage grasses decrease in α‐linolenic acid (ALA) and ΣFA content, and this is exacerbated in tall summer annuals. We compared ALA and ΣFA content within pearl millet [Cenchrus americanus (L.) Morrone] fractions to determine if decreases are attributable to advancing maturity within fractions or simply to the change in proportion of the fractions. Samples were collected six times, from early vegetative to late boot stage. Lamina and pseudostem fractions were separated, and whole plant FA composition was calculated from the weighted average of the fractions. As pearl millet matured, ALA and ΣFA content decreased by 55 to 56% within pseudostems and on a whole‐plant basis, although only by 10% in laminae. The ALA proportion of ΣFA decreased by 14% on a whole plant basis, despite not changing within constituent fractions.

Morphology and Structure of Amino Fatty Acid Intercalated Montmorillonite

For nanocomposite production, montmorillonite clays are often modified with organic surfactants to favor its intermixing with the polymer matrix. In the present study, Na+-montmorillonite (Na+-MMT) was subjected to organo-modification by cation exchange with protonated 12-aminolauric (ALA). The amount of the amino fatty acid surfactants loaded were 25, 50, 100 and 200% times the CEC of Na+-montmorillonite. X-ray diffraction (XRD) analysis revealed the interlayer spacing of the clay increased from 1.25 to 1.82 nm with increasing ALA content. The amino fatty acid chain were considered to be arranged into a flat monolayer structure at low surfactant loading, while they form a bilayered to a pseudotrilayered structure at high surfactant loading. Infrared spectroscopy (FTIR) revealed the alkylchains adopt a gauche conformation indicating their disordered state. Thermogravimetric analyses (TGA) revealed that the surfactant in the clay were thermally stable with Td ranging from 353 to 417°. The difference in the melting behavior of the pristine fatty amino fatty acids and confined fatty acids in the interlayer galleries of the clay were evaluated differential scanning calorimerty (DSC). The melting temperatures (Tm) of the amino fatty acid in the clay were intitially higher than the free amino fatty acid but decreased with increasing surfactant loading. The amino fatty acid may be tethered to the clay structure via ionic interaction or ion-dipole attraction. Scanning electron microscopy (SEM) revealed that the organo-clays have a disordered and flaky morphology. The present study suggests that 12ALA is a suitable intercalating agent for the production of organophilic clay materials.

Purification of Bovine Bone Oligophosphopeptide with High Calcium-binding Activity by &lt;i&gt;Bacillus cereus &lt;/i&gt;MBL13 Collagenolytic Protease

A demineralized bovine bone was hydrolyzed by a specific bone-degrading collagenolytic protease extracted from Bacillus cereus MBL13 (isolated from chopped animal bone wastes) to utilize its collagen in nutraceuticals with high calcium bioavailability. Bovine bone peptide (BBP), a novel oligophosphopeptide with a high calcium binding ability (8.25 mmol/g-protein), was isolated from bovine bone hydrolysates by Chelex 100, ultrafiltration, hydroxyapatite chromatography, gel filtration chromatography, and reverse-phase high performance liquid chromatography. The results showed that demineralization treatment can significantly increase hydrolysis (p < 0.05). The amino acid content of BBP showed that the Asp, Ala, Tyr, and Thr contents were remarkable increments compared to the bone hydrolysates. The molecular mass of BBP was found to be around 3.305 kDa through SDS-PAGE and MALDI-TOF mass spectrometry. FT-IR spectra showed characteristic absorption peaks. Moreover, BBP exhibited higher calcium binding activity than that of casein oligophosphopeptide (CPP). Therefore, this study demonstrated that B. cereus MBL13 collagenolytic protease (BCC) could degrade bovine bone collagen, and prepared oligophosphopeptide could be utilized as a nutraceutical with high calcium-binding activity.

Codon usage analysis of photolyase encoding genes of cyanobacteria inhabiting diverse habitats.

Nucleotide and amino acid compositions were studied to determine the genomic and structural relationship of photolyase gene in freshwater, marine and hot spring cyanobacteria. Among three habitats, photolyase encoding genes from hot spring cyanobacteria were found to have highest GC content. The genomic GC content was found to influence the codon usage and amino acid variability in photolyases. The third position of codon was found to have more effect on amino acid variability in photolyases than the first and second positions of codon. The variation of amino acids Ala, Asp, Glu, Gly, His, Leu, Pro, Gln, Arg and Val in photolyases of three different habitats was found to be controlled by first position of codon (G1C1). However, second position (G2C2) of codon regulates variation of Ala, Cys, Gly, Pro, Arg, Ser, Thr and Tyr contents in photolyases. Third position (G3C3) of codon controls incorporation of amino acids such as Ala, Phe, Gly, Leu, Gln, Pro, Arg, Ser, Thr and Tyr in photolyases from three habitats. Photolyase encoding genes of hot spring cyanobacteria have 85% codons with G or C at third position, whereas marine and freshwater cyanobacteria showed 82 and 60% codons, respectively, with G or C at third position. Principal component analysis (PCA) showed that GC content has a profound effect in separating the genes along the first major axis according to their RSCU (relative synonymous codon usage) values, and neutrality analysis indicated that mutational pressure has resulted in codon bias in photolyase genes of cyanobacteria.

Establishment of a model to evaluate the nutritional quality of Bombyx mori Linnaeus (Lepidoptera, Bombycidae) pupae lipid based on principal components

Silkworm pupae are a source of edible lipid with a high content of unsaturated fatty acids (UFAs) (70% of total lipid content) and are becoming a focus of pharmaceutical and dietary research in the functional oil field. To study the nutritional value of different silkworm strains, principal component analysis (PCA) was used to establish a mathematical model and cluster analysis on silkworm pupae lipid (SPL) in 90 strains based on Z-score. Single-factor correlation analysis indicated that the PUFAs content was significantly positively correlated with the α-linolenic acid (ALA) (ρ=0.98) and negatively correlated with the oleic acid (OA) (ρ=−0.73) contents, and comprehensive of principal components mathematical model (PC=0.148ZX1+0.002ZX2−0.197ZX3−0.338ZX4+0.220ZX5+0.304ZX6+0.314ZX7, ZXi is the standard score (Z-score) of X1, which was calculated as follow: ZXi=(Xi−X−)/S, where X1: palmitic acid, X2: palmitoleic acid, X3: stearic acid, X4: OA, X5: linoleic acid, X6: ALA, X7: PUFAs. X− is the arithmetic mean content of variable i, and S is the standard deviation of variable i for all samples included in the analysis.) showed the amount of ALA and PUFAs were the key factors determining the nutritional value of the pupae lipid. Cluster analysis on the composite scores calculated by the model of the principal component divided the 90 strains into three groups. A cluster of 6 strains (XHR, XIFF, ZX, YT, YO and BTN) with the best nutritional value was characterized by high contents of ALA and PUFAs and a low content of oleic acid.

Using a gradient in food quality to infer drivers of fatty acid content in two filter-feeding aquatic consumers

Inferences about ecological structure and function are often made using elemental or macromolecular tracers of food web structure. For example, inferences about food chain length are often made using stable isotope ratios of top predators and consumer food sources are often inferred from both stable isotopes and fatty acid (FA) content in consumer tissues. The use of FAs as tracers implies some degree of macromolecular conservation across trophic interactions, but many FAs are subject to physiological alteration and animals may produce those FAs from precursors in response to food deficiencies. We measured 41 individual FAs and several aggregate FA metrics in two filter-feeding taxa to (1) assess ecological variation in food availability and (2) identify potential drivers of among-site variation in FA content. These taxa were filter feeding caddisflies (Family Hydropyschidae) and dreissenid mussels (Genus Dreissena), which both consume seston. Stable isotopic composition (C and N) in these taxa co-varied across 13 sites in the Great Lakes region of North America, indicating they fed on very similar food resources. However, co-variation in FA content was very limited, with only one common FA co-varying across this gradient (α-linolenic acid; ALA), suggesting these taxa accumulate FAs very differently even when exposed to the same foods. Based on these results, among-site variation in ALA content in both consumers does appear to be driven by food resources, along with several other FAs in dreissenid mussels. We conclude that single-taxa measurements of FA content cannot be used to infer FA availability in food resources.