A crystalline lipid phase in a dry biological system: evidence from X-ray diffraction analysis of Typha latifolia pollen

The temperature limits for germination in Typha latifolia pollen lie within the range 4-40 degrees C. These limits correlate at the low-temperature end with the 'crystallization' of endogenous triacylglycerols and on the high-temperature end with the 'melting' of a gel-like lipid component in intact pollen. X-ray diffraction analysis was used to structurally characterize and to trace the latter gel-like lipid from the intact pollen through a range of pollen lipid fractions. We tentatively identify this component as a fatty acyl sterol ester and present evidence that it resides in the exine of the pollen grain. Its thermotropic behavior is insensitive to pollen hydration. The possibility of interpreting a crystalline lipid phase as being membrane-derived when in fact it originates from contaminating non-membranous neutral lipid is discussed. The total lipid content of T. latifolia pollen is 123 mg/g dry weight, of which 37% is polar lipid. The neutral lipid consists primarily of triacylglycerols and of the aforementioned sterol ester, which represents 0.34% (w/w) of pollen dry weight. The polar lipid fraction has phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid as major components with lesser amounts of phosphatidylglycerol and phosphatidylinositol. Palmitic (16:0) and linoleic (18:2) acids, in a 1:2 molar ratio, constitute the major fatty acids of both polar and neutral lipid fractions with lesser amounts of linolenic (18:3), oleic (18:1) and stearic (18:0) acid in evidence.     

Membrane Lipids of Mycoplasma hominis

Essentially all of the lipids of Mycoplasma hominis (200 mug/mg of cell protein) were found to be located in the cell membrane. Over one-half were neutral lipids incorporated from the growth medium and consisting of 43% free cholesterol, 19% esterified cholesterol, 23% triglycerides, 10% free fatty acids, and small amounts of di- and monoglycerides. The polar lipids accounting for about 40% of the total were synthesized by the organisms. Phosphatidylglycerol was the predominant lipid of this fraction. The minor components, tentatively identified as lysophosphatidylglycerol and phosphatidic acid, seem to represent breakdown products of phosphatidylglycerol. No glycolipids were detected. Being unable to synthesize long-chain fatty acids, M. hominis utilized the fatty acids of the growth medium for polar lipid synthesis, preferentially the saturated ones, so that the polar lipids had highly saturated hydrocarbon chains. It is proposed that the large take up of unsaturated neutral lipids and cholesterol from the medium offsets the marked condensing effect of the saturated polar lipids, although electron paramagnetic resonance spectrometry of spin-labeled fatty acids incorporated into the M. hominis membrane indicated that the lipid region is still more rigid than that of the Acholeplasma laidlawii membrane.     

The lipid composition of Acer pseudoplatanus cells grown in culture

Cells of Acer pseudoplatanus were grown in batch suspension culture for 22 days. The cultures were initiated at high cell density of 2 × 10⁵ cells per ml of culture. Growth was characterised by a short lag phase, an exponential phase of rapid cell division and growth, and finally a stationary phase. Quantitative but not qualitative changes were observed in total lipid content, fatty acids and phospholipids at different stages of growth. Total lipids, phospholipids and fatty acids showed maximum concentrations in 12 day old cells. The major phospholipids isolated were phosphatidylcholine and phosphatidylethanolamine with minor amounts of phosphatidic acid and lysophosphatides. Other lipid components present were mono- and digalactosyl diglycerides, cerebrosides, sterol glucosides, free fatty acids and esterified sterol glucosides. The major constituent fatty acids were myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2) and linolenic acid (18:3). During exponential cell growth the proportion of 16:0, 18:2 and 18:3 constituted nearly 90% of the total fatty acids. Triglycerides were the major repository of myristic acid (14:0) with substantial amounts of palmitic acid (16:0), whereas phospholipids contained 16:0, 18:2 and 18:3 in high amounts.     

Lipid profile of cultured cells of apple (Malus sylvestris) and apple tissue

The potentiality of apple cell cultures to synthesize not only higher quantities of lipids than apple fruit but also different classes of lipids is noted. Total lipid was 15-fold higher in apple callus than in the original tissue. On callusing, linoleic acid decreased from 66% to 14%, while linolenic acid showed a very large increase from 0.9% to 44%. Stearic and oleic acids also increased in callus. The relative amounts of sterol/hydrocarbon and diglyceride fractions were higher in callus cultures, while apple tissue showed higher levels of triglycerides and sterol. Phosphatidylethanolamine and phosphatidylglycerol seemed to be newly synthesized during callusing while other phospholipids such as lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidylinositol and phosphatidic acid decreased. There was much higher glycolipid in apple callus than in the original tissue. The ratio of neutral lipid to polar lipid was higher in apple than in apple callus.     

Die Lipide von Endomycopsis vernalis bei verschiedener Stickstoff-Ernährung

1. Endomycopsis vernalis was cultivated on media with different N supply: series A 1%, series B 0,125% asparagine. Sonified cells were extracted and yielded 14.3% (A) and 65.3 (B) total lipids/non lipid dry matter respectively.
2. Neutral and complex lipids were separated by rubber membrane dialysis. There is no difference in the percentage of complex lipids of both series. The increase of lipids in cells grown on low N level is due to a higher content of neutral lipids.
3. Components of the neutral lipids, analysed by DC, were diglycerides, triglycerides, free and esterified ergosterol. Their percentage is influenced by the nutritional conditions. There is a significant increase of triglycerides and of sterol esters in the high lipid cells of series B.
4. Methyl esters of component fatty acids of glycerides and sterol esters were analyzed by GLC. Saturated acids C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, monoenic acids C₁₆ and C₁₈, linoleic and linolenic acids were found to be present. Major acids were in all cases 18:1 (17–57%), 18:2 (18–50%) and 16:0 (10–18%). Linolenic acid is higher in di-and triglycerides of low lipid cells of series A than in high lipid cells of series B. Both qualitative and quantitative differences of fatty acids were found in sterol esters of series A and B respectively.
5. The major components of complex lipids, identified by DC and isolated by CC, in both series, were phosphatidyl choline (A:36.5, B:41.0%) and phosphatidyl ethanolamine (A:24.9, B:20.5%) in addition to small amounts of lysophosphatidyl choline, lysophosphatidyl ethanolamine, phosphatidyl serine, monophosphoinositide, diphosphatidyl glycerol and, possibly cerebroside like substances.
6. Methyl esters of the fatty acids of phosphatidyl choline and ethanolamine from both series were determined by GLC. In all samples 16:0, 18:0, 18:1, 18:2 and 18:3 acids were present besides of traces of 16:1 and 17:0. In contrast to neutral lipids the major acid of phospholipids is linoleic (53–58%), followed by oleic (8–24%) and linolenic acid (1–18%). The percentages of palmitic (4–8%) and stearic acids (tr.-1%) are small. Low lipid cells of series A differ from high lipid cells of series B by an increase of linolenic, and a decrease of linoleic acids, both in phosphatidyl choline and phosphatidyl ethanolamine.

     

Lipid and sterol composition of the pollen of the west african oilpalm, Elaeis guineensis

The lipid classes, fatty acid methyl esters and the sterols of oilpalm pollen were analysed. The neutral lipid fraction consisted of triglycerides, esterified and free sterols and trace amounts of hydrocarbons. Monogalactosyl and digalactosyl diglycerides, phosphatidyl choline, phosphatidyl inositol and phosphatidyl ethanolamine represented the polar lipids. The major fatty acids were linoleic, palmitic and linolenic acids together with small to trace amounts of oleic, stearic, arachidic, myristic, lauric, palmitoleic and margaric acids. Unsaturated fatty acids predominated over saturated ones in the ratio of 3:2. The 4-desmethyl sterols were the major phytosterols in the free form but they constituted a lower proportion of the sterols in the esterified state. 28-Isofucosterol was isolated and characterized as the principal sterol.     

The lipid composition of a halotolerant species of Staphylococcus epidermidis.

Studies were carried out on the lipid composition of a halotolerant Staphylococcus epidermidis isolated in pure culture from a growth medium for extreme halophiles containing 25% NaCl. The four major polar lipid components in this bacterium were found to be: (a) glycerophosphoryl diglucosyl diglyceride (10% by weight) with structure 3(1)-O-(-sn-glycerol-1-phosphoryl-6'-O=(beta-D glucopyranosyl-(1 leads to 6)- O-beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol; (b) diglucosyl diglyceride (15% by weight) with structure 3(1)-O-(beta-D-glucopyranosyl (1 leads to 6)-O-beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol; (c) monoglucosyl diglyceride (3% by weight) with structure 3(1)-O-(beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol, and (d) phosphatidylglycerol (60% by weight) with structure 1,2 diacyl-sn-glycero-3-phosphoryl-1'-sn-glycerol. Phosphatidic acid, cardiolipin, lysophosphatidylglycerol and three unidentified phospholipids were also detected in small amounts. Each lipid component had essentially the same fatty acid composition namely, anteiso-15:0 (60-75%), anteiso-17:0 (18-24%), iso-17:0 (8--10%), and small amounts of palmitic and stearic acids (2-5%). The fatty acids were non-randomly distributed in phosphatidylglycerol, the shorter chain anteiso 15:0 fatty acid being exclusively esterified to the 2-position and the longer chain anteiso- and iso-17:0 fatty acids at the 1-position. The fatty acid composition was not affected by increaseing NaCl content in the medium in the rande 0--15% but the proportion of anteiso-15:0 increased greatly when the salt concentration was increased to 25%. The proportions of ionic polar lipids were modified to give an increased net negative charge per mol ionic lipids when NaCl in the medium was increased from 15 to 25%, but the proportions of neutral glycolipids remained fairly constant.     

Polar lipids in phototrophic bacteria of the Rhodospirillaceae and Chromatiaceae families.

The polar lipids of photosynthetic purple bacteria of the genera Chromatium, Thiocapsa, Thiocystis, Ectothiorhodospira, Rhodopseudomonas, Rhodospirillum, and Rhodomicrobium were analyzed. Characteristic compositions of the polar lipids were found for most of the Rhodospirillaceae and Chromatiaceae species. Phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin were the major phospholipids in most species. Phosphatidylcholine was present as a major component in all species of the genus Ectothiorhodospira, but was not detected in the remaining Chromatiaceae. It was also present in most of the Rhodospirillaceae species. No glycolipids were found in any of the Ectothiorhodospira species. In the Rhodospirillaceae, the glycolipids mono- and digalactosyl diglycerides were generally absent. Sulfoquinovosyl diglyceride was present in significant amounts in at least three species of the Rhodospirillaceae and may have been present in most of them, but only in traces. All of the Chromatiaceae species contained several glycolipids, one of which was similar to monogalactosyl diglyceride. Ornithine lipids were found in large amounts in most Rhodospirillaceae, but were absent in Ectothiorhodospira and in the other Chromatiaceae. The species examined could be divided into three groups on the basis of their lipid composition: (i) the genus Ectothiorhodospira; (ii) the remaining Chromatiaceae; and (iii) the Rhodospirillaceae. The data presented are compared with those available in the literature, and differences from other phototrophic organisms are discussed.     

Composition of the protoplast membrane from Saccharomyces cerevisiae

1. Protoplasts of Saccharomyces cerevisiae N.C.Y.C. 366 were prepared by incubating washed exponential-phase cells in buffered mannitol (0.8m) containing 10mm-magnesium chloride and snail gut juice (about 8mg. of protein/ml. of reaction mixture). Protoplast membranes were obtained by bursting protoplasts in ice-cold phosphate buffer (pH7.0) containing 10mm-magnesium chloride. 2. Protoplast membranes accounted for 13-20% of the dry weight of the yeast cell. They contained on a weight basis about 39% of lipid, 49% of protein, 6% of sterol (assayed spectrophotometrically) and traces of RNA and carbohydrate (glucan+mannan). 3. The principal fatty acids in membrane lipids were C(16:0), C(16:1) and C(18:1) acids. Whole cells contained a slightly greater proportion of C(16:0) and a somewhat smaller proportion of C(18:1) acids. Membrane and whole-cell lipids included monoglycerides, diglycerides, triglycerides, sterols, sterol esters, phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol+phosphatidylserine. Phosphorus analyses on phospholipid fractions from membranes and whole cells showed that membranes contained proportionately more phosphatidylethanolamine and phosphatidylinositol+phosphatidylserine than whole cells, which in turn were richer in phosphatidylcholine. Phospholipid fractions from membranes and whole cells had similar fatty acid compositions. 4. Membranes and whole cells contained two major and three minor sterol components. Gas-liquid chromatography, mass spectrometry and u.v. and i.r. spectra indicated that the major components were probably Delta(5,7,22,24(28))-ergostatetraen-3beta-ol and zymosterol. The minor sterol components in whole cells were probably episterol (or fecosterol), ergosterol and a C(29) di-unsaturated sterol. 5. Defatted whole cells contained slightly more glutamate and ornithine and slightly less leucine and isoleucine than membranes. Otherwise, no major differences were detected in the amino acid compositions of defatted whole cells and membranes.     

The lipids of phosphorescent Vibrio albensis bacteria]

The lipid composition of fluorescent vibrios, V. eltor and nonagglutinating vibrios has been studied. In the fraction of polar lipids phosphatidylethanolamine, phosphatidylinositol and cardiolipin and in the fraction of neutral lipids monoglycerides, free fatty acids, diglycerides, triglycerides, sterol esters have been identified. The fatty acid composition of some classes of neutral lipids have been determined. Both similarity and differences between the strains under study in their lipid and fatty acid composition have been established.     

Lipids of Branhamella catarrhalis and Neisseria gonorrhoeae.

Three strains of Branhamella catarrhalis and three strains of Neisseria gonorrhoeae were analyzed with regard to their phospholipid and neutral lipid composition. B. catarrhalis (ATCC 23246) contained 5.12 +/- 0.34% lipid, determined gravimetrically, compared to 8.56 +/- 0.15% and 9.73 +/- 0.06% for two strains of N. gonorrhoeae. Cardiolipin, phosphatidylglycerol, and phosphatidyl-ethanolamine were identified in extracts of both species. In addition, B. catarrhalis contained small amounts of phosphatidylcholine, and N. gonorrhoeae contained small amounts of lyso-phosphatidylethanolamine, which accumulated with autolysis accompanying late cell culture growth. The kinetics of change of relative amounts of phospholipids in both species were measured and found to differ substantially. Neutral lipid accounted for 30.4% of the total lipid of B. catarrhalis (ATCC 23246) and 7.6% of the total lipid of N. gonorrhoeae NYH 002. Hydrocarbons, triglycerides, free fatty acids, coenzyme Q, diglycerides, and free hydroxy fatty acids were identified in the neutral lipid fraction of both species. The three strains of N. gonorrhoeae, sensitive, intermediate, and resistant to penicillin, exhibited no significant difference in the composition or metabolism of phospholipid.     

Biomass production,total protein,chlorophylls, lipids and fatty acids of freshwater green and blue-green algae under different nitrogen regimes

Two green algae (Chlorella vulgaris and Scenedesmus obliquus) and four blue-green algae (Anacystis nidulans, Microcystis aeruginosa, Oscillatoria rubescens and Spirulina platensis) were grown in 81 batch cultures at different nitrogen levels. In all the algae increasing N levels led to an increase in the biomass (from 8 to 450 mg/l), in protein content (from 8 to 54 %) and in chlorophyll. At low N levels, the green algae contained a high percentage of total lipids (45 % of the biomass). More than 70 % of these were neutral lipids such as triacylglycerols (containing mainly 16:0 and 18:1 fatty acids) and trace amounts of hydrocarbons. At high N levels, the percentage of total lipids dropped to about 20 % of the dry weight. In the latter case the predominant lipids were polar lipids containing polyunsaturated C₁₆ and C₁₈ fatty acids. The blue-green algae, however, did not show any significant changes in their fatty acid and lipid compositions, when the nitrogen concentrations in the nutrient medium were varied. Thus the green but not the blue-green algae can be manipulated in mass cultures to yield a biomass with desired fatty acid and lipid compositions. The data may indicate a hitherto unrecognized distinction between prokaryotic and eukaryotic organisms.     

Seasonal changes in lipid content and composition of the polychaete Nereis (Hediste) diversicolor

The lipid content and composition of Nereis (Hediste) diversicolor O. F. Müller (Annelida, Polychaeta, Nereidae) a mud-dwelling, intertidal errant polychaete in the Tagus estuary (Portugal), were examined on the monthly basis by lipid extraction, TLC and capillary GC. In this estuary, N. diversicolor is by far the dominant species among polychaeta and the main food item in the natural diet of several flatfishes. The biochemical elucidation of its lipid structure and distribution throughout the year, described in this study, provides information not only about the physiological role of lipids in the animal under consideration but also about dietary fatty acid requirements of some flatfishes in the wild and under laboratory conditions.The total lipid content varied between a maximum of 19.3% lyophilized dry weight in February (4.4% fresh weight) and a minimum of 6.6% in August (1.9% fresh weight). The major lipid classes were triacylglycerol, phospholipid, free sterol, free fatty acid, sterol ester/wax ester and alkyldiacylglycerol.The fatty acid composition was rather unsaturated with a 1:2 mean ratio of n-3: n-6. The major fatty acids were C160:0, C18:1n-9, C18:2n-6, and C20:5n-3; there were smaller amounts of C180:0, C18:1n-11, C18:1n-7, C18:3n-3, C20:1, C20:2n-6, C20:4n-6, C22:2, C22:5n-3, and many other fatty acids were detected at trace levels. The unsaturation ranged from 36.9 mg/g dry weight in summer to 107.4 mg/g in winter. An accumulation of fatty acids from plant origin was evident, in particular linoleic acid (C18:2n-6), which was quantitatively one of the major fatty acids throughout the year.     

Effect of paclobutrazol on membrane lipids in apple seedlings

The effect of paclobutrazol [( 2RS, 3RS )-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2, 4-triazol-1-yl) pentan-3-ol] on the fatty acid composition of polar lipids and on the sterol content in apple ( Malus domestica Borkh. cv. York Imperial) seedlings was determined. Polar lipids isolated from leaves, stems and roots included mono- and digalactosyldiglycerides and the phospholipids phosphatidylinositol, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The predominant fatty acids in membrane polar lipids were palmitic (C16:0), linolnic (C18:2) and linolenic (C18:3). The predominant sterol, both free and esterified, was β-sitosterol. There were no significant alterations in the fatty-acid composition of glyco- and phospholipids from paclobutrazol-treated apple seedlings. In contrast, a significant decrease in the content of β-sitosterol and campesterol occurred in treated tissues. The decline in sterol content continued with increasing duration of paclobutrazol treatment, and was most pronounced in the root tissue.     

Treponeme outer envelope: chemical analysis.

The chemical composition of the outer envelope (OE) of Treponema phagedenis biovar Kazan 5 was investigated. After cultivation in a lipid-defined medium, the OE was removed from the cells with 0.7 mM sodium dodecyl sulfate. The solubilized OE was reaggregated by dialysis against 20 mM MgCl2, washed, lyophilized, and subjected to chemical analysis. The average yield of OE was 14.6% of the whole cell (WC) dry weight. The magnesium content was 0.683 mug/mg OE. Peptidoglycan components such as muramic acid and ornithine were detected in the WC but not in the OE, and diaminopimelic acid was absent in both WC and OE. The OE contained protein (60-73%), carbohydrate (1-2%), and lipid (4-5%), primarily polar lipid. The major polar lipids were monogalactosyldiglyceride (43%) and phospholipid (57%), of which phosphatidylcholine was the main phospholipid component, with phosphatidylethanolamine present in lesser amounts.     

Lipids in plant tissue cultures IV. The characteristic patterns of lipid classes in callus cultures and suspension cultures

Lipids from callus cultures and suspension cultures of higher plants constitute 5 to 8% of the dry tissue's weight.The predominant lipid classes are the sterols, steryl esters, steryl glycosides and esterified steryl glycosides. Considerable amounts of a variety of sterylglycolipids, whose structures are not completely elucidated, are also present. Triglycerides and phospholipids occur in small proportions, whereas monogalactosyl diglycerides, digalactosyl diglycerides and sulfoquinovosyl diglycerides are present only in traces, if at all.β-Sitosterol is the predominant constituent sterol, stigmasterol and campesterol as well as a variety of as yet unidentified sterols occur in smaller proportions. The major constituent fatty acids are palmitic, oleic, linoleic and linolenic acids. Saturated very long-chain fatty acids are found in smaller proportions. Unusual fatty acids, such as epoxy acids, which occur in the seed lipids of certain plants, are not found in tissue cultures derived from these plants. Clucose and traces of galactose are the only sugars obtained by acid hydrolysis of the glycolipids occurring in plant tissue cultures.     

The role of glucose in the lipid metabolism of the rat tapeworm Hymenolepis diminuta

The composition of the neutral lipids and the phospholipids, and the role of glucose in the lipid metabolism of prepatent (12-day-old) Hymenolepis diminuta has been studied in vitro. Triglyceride was the most abundant lipid present; substantial amounts of sterol and sterol ester, diglyceride, free fatty acids and monoglycerides were also present. The phospholipids, which were qualitatively and quantitatively similar to those of other invertebrates and vertebrates, were, in order of abundance, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphoinositide, lysophosphatidylcholine, cardiclipin, phosphatidic acid, lysophosphatidic acid and phosphatidylglycerol. Small amounts of glucose carbon were incorporated into the lipids, principally the water soluble (glycerol) moiety of the triglycerides; only traces were incorporated into the phospholipids. Small amounts of glucose were converted to inositol and galactose. The principal pathway of triglyceride synthesis is suggested to be via the α-glycerophosphate-phosphatidic acid-diglyceride pathway.     

Effect of copper on membrane lipids and on methane monooxygenase activity of Methylococcus capsulatus (Bath)

The effect of copper supplementation on growth, methane monooxygenase activity and lipid composition of Methylococcus capsulatus (Bath) was studied. Copper increased biomass yield, methane monooxygenase activity and phospholipid content from 7.7 to 10.2% of dry weight. Cells from copper-deficient and copper supplemented cultures contained the same major fatty acids but in the presence of copper only the contents of C16:0 and the three C16:1 isomers were increased while the contents of C14:0 and cyclic C17:0 remained unchanged. Phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylglycerol and cardiolipin were analysed amongst the polar lipids. PE was the main component (about 60 mol-%) but the most notable copper-induced increment occurred in the proportion of PC, from about 10 to 16 mol-%. Concomitantly with this increment the fatty acids of PC were changed so that the mol-% of C16: 1 isomers were increased at the expense of other acids. Similar trends were seen also in the fatty acid compositions of other polar lipid fractions. It is therefore concluded that phosphatidylcholine would be one of the key factors when the role of membranous lipids in methane monooxygenase activity is to be considered.     

The lipid content of cell walls obtained from juvenile,yeast-like and filamentous cells ofCandida albicans

Purified cell walls ofCandida albicans obtained from juvenile cells, mature yeast-like cells and filamentous cells were analyzed for their lipid components. Chloroform: methanol (2:1 v v) extraction of the acetone-treated dried cell walls indicated the total lipid content to be 2.1% of the dry weight of the juvenile cell walls, 1.8% of the mature yeast-like cell walls and 4.5% of the filamentous cell walls. Separation of the chloroform: methanol extractable fraction through a silicie acid column and quantitative determination of the fractions showed significant amounts of sterol esters, triglycerides, sterols, free fatty acids, and phospholipids in these extracts. Following acetone extraction sterols were shown to constitute a greater percentage of the cell wall of juvenile cells than mature cells. Thin-layer chromatography separated the acetone-extractable lipids into at least four components. Diethyl ether extracts of the cell walls indicated the presence of small amounts of glycerol phospholipids in the cell walls of juvenile and mature yeast cells. Boiling 95% ethanol also removed a small lipid fraction from the cell walls of both juvenile and mature yeast which could include sphingosine phosphatides or glycosides.     

The bioenergetic fuel for non-feeding larval development in an endemic palaemonid shrimp from the Iberian Peninsula,Palaemonetes zariquieyi

Palaemonetes zariquieyi, an endemic palaemonid species of shrimp that lives in freshwater and brackish coastal habitats in eastern Spain, shows an abbreviated, non-feeding larval development comprising only three zoeal stages. To identify the endogenous bioenergetic fuel that allows for food-independent development from hatching to metamorphosis, larvae were reared under controlled laboratory conditions, and ontogenetic changes in dry weight (W), elemental (CHN), and lipid composition (total lipids, principal lipid classes, and fatty acids [FA]) were quantified at the onset of each zoeal stage and in the first juvenile. Values of W, C, and H per larva and per mass unit of W decreased throughout the time of larval development, while the N content showed only a weak decline (suggesting strong lipid but only little protein degradation). Correspondingly, directly measured values of total lipids (both in μg/larva and in % of W) decreased gradually, with neutral lipids (NL) consistently remaining the predominant and most strongly used fraction; sterol esters and waxes were not detected. In contrast to the NL, the fraction of polar lipids (PL) per larva remained stable and, as a consequence, tended to increase as a percentage of total lipids. Likewise, other important lipid fractions such as free FA and cholesterol remained stable throughout the time of larval development. Among the FA, palmitic (16:0), oleic (18:1n–9), linoleic (18:2n–6), and eicosapentaenoic (20:5n–3) acid were predominant, showing a significant decrease during larval development; stearic (18:0), vaccenic (18:1n–7), and arachidonic acid (20:4n–6) were found only in small amounts. Our results indicate that the lecithotrophic development of P. zariquieyi is primarily fuelled by the utilization of lipids (especially triacylglycerides and other NL), which is reflected by a decreasing carbon content. Proteins and PL, by contrast, are preserved as structurally indispensable components (nerve and muscle tissues, cell membranes). The abbreviated and non-feeding mode of larval development of P. zariquieyi may have an adaptive value in land-locked freshwater habitats, where planktonic food limitation is likely to occur. The patterns of reserve utilization are similar to those previously observed in other palaemonid shrimps and various other groups of decapod crustaceans with lecithotrophic larvae. This suggests a multiple convergent evolution of bioenergetic traits allowing for reproduction in food-limited aquatic environments.