An imbalance in the natural cation ratio in the water as a factor affecting the synthesis of lipids and fatty acids in fish eggs

The effects on the lipid status of developing embryos of a disturbed natural ratio of cations in water as a result of the pollution of water bodies by waste with a high potassium content (130-140 mg/I) were studied in the laboratory. The results obtained confirm the indication of reduced lipid synthesis and altered formation of phospholipids in embryos developing in a medium with a disturbed natural ratio of cations. In addition, the lysophospholipid fraction increased in these embryos, which indicates activation of phospholipid hydrolysis. It was also found that changes in the salt regime lead to a decreased content of cholesterol, the main membrane thickener. It was proposed that the changes discovered lead to disturbed stability and permeability of the membranes of fish eggs, with the subsequent death of embryos.     

Acquisition of desiccation tolerance in developing wheat embryos correlates with appearance of a fluid phase in membranes

Membrane behaviour in developing wheat (Triticum aestivum cv Priokskaya) embryos was studied in relation to the acquisition of desiccation tolerance, using spin probe techniques. Fresh embryos were able to develop into seedlings at day 15 after anthesis, but it took 18 d before fast‐dried, isolated embryos could germinate. On the basis of membrane integrity measurements it was estimated that between 14 and 18 d after anthesis the proportion of embryonic cells surviving fast drying increased and the critical moisture content, to which embryonic cells could be dehydrated, decreased. Apparently, embryonic cells do not acquire the same level of desiccation tolerance simultaneously. Only when all cells had become desiccation tolerant was germination of air‐dried embryos possible. Using 5‐doxylstearic acid as the probe molecule, an approximately similar lipid–water interface ordering of membranes was observed in all hydrated embryos, irrespective of age. Dehydration had a dual effect on the lipid interface: further ordering of the major part of the interface and the appearance of additional, disturbed regions. The proportion of these regions correlated with the proportion of desiccation‐tolerant cells. We propose that the membrane surface disturbance be caused by endogenous amphiphiles that partition from the cytoplasm into membranes during drying. The absence of such disturbed regions in dried, desiccation‐sensitive embryos might reflect a lack of sufficient amphiphiles. The relevance of membrane surface disturbance for desiccation tolerance is discussed.     

Changes in the biochemical composition of Euphausia superba Dana embryos during early development

Summary The biochemical composition of developing Euphausia superba Dana embryos has been examined at three stages: fresh spawned, gastrula, and limb bud. Fresh spawn embryos had 31% lipid, 1.0% carbohydrate, and 57% protein on a gram dry weight basis. Throughout development lipids were utilized more slowly than in other crustacean embryos for a total utilization of 37.5%. Overall, 35.6% of the starting protein was utilized. On a weight basis, twice as much protein than lipid was used during development, and it appeared that, energetically, protein and lipid contributed equally to the energetics of the developing embryo. Carbohydrate was evidently a minor substrate in early development, although the level increased 38% during development. Average water content was 86% in fresh spawned embryos and 88% in the gastrula stage. The average dry weight of the embryos throughout development was 30 g. The features of planktonic embryos are contrasted with demersal embryos and the atypical metabolic pattern of krill embryos is discussed.MOA dedicates this paper to the memory of Dr. Mary Alice McWhinnie, for her encouragement during my years at DePaul University and for the opportunity to participate in her research     

顽拗性黄皮种子脱水过程中活性氧清除酶活性的变化

以正常性种子花生为对照,研究了顽拗性黄皮种子脱水过程中活性氧清除酶、膜脂过氧化作用以及电解质渗漏率的变化。随着含水量的下降,黄皮胚的电解质渗漏率和膜脂过氧化产物丙二醛(MDA)含量均显著增加;当黄皮胚含水量下降至40％后,SOD活性开始急剧下降,而POD和CAT活性在胚含水量下降过程中呈现出缓慢下降的趋势。花生胚在含水量从45％降至14％的过程中,电解质渗漏率没有明显增加,MDA含量只有少量增加;当含水量降至14％后,电解质渗漏率出现少量增加。花生胚脱水初期,活性氧清除酶活性明显增加,并在整个脱水过程中维持较高的水平。以上结果表明顽拗性种子黄皮的脱水敏感性与活性氧清除酶相对活性变化有关。脱水引起黄皮胚活性氧清除酶活性降低,活性氧清除能力下降,膜脂过氧化作用加强,膜透性增大。黄皮胚的膜系统可能是脱水伤害的靶位之一。     

Lipid composition of somatic and zygotic embryos from Prunus avium. Effect of a cold treatment on somatic embryo quality

In order to evaluate the quality of Prunus avium somatic embryos, a comparison of lipid composition between somatic and zygotic embryos was undertaken. In both zygotic and somatic embryos, neutral glycerolipids (NL) and phosphatidylcholine (PC) were the 2 major lipid classes. The content of NL increased over the course of development in zygotic embryos and reached 490 μg per embryo, while the PC content reached 100 μg per embryo. However, the contents of NL and PC in somatic embryos were similar to immature zygotic embryos at stage 3. Fatty acid composition of NL from both zygotic and somatic embryos revealed more unsaturated than saturated fatty acids. In somatic embryos, the saturated/unsaturated fatty acid ratios of NL and phosphatidylinositol (PI) were similar to those observed in immature zygotic embryos up to stage 6. Conversely, in phosphatidylethanolamine (PE) the ratio was similar to the ratio observed in mature zygotic embryos, at stage 7. Histological studies confirmed the immaturity of somatic embryos: no protein or lipid reserves were observed in the vacuolated cotyledonary cells. Maturation of somatic embryos was improved by a 2-month cold period. In cold-treated somatic embryos, both NL and PC increased to levels comparable to those observed in mature zygotic embryos, and the PE content reached 10 times the level of that in mature zygotic embryos. The cold treatment induced a large increase in the saturated/unsaturated fatty acid ratio in phospholipids but only a slight increase in that of neutral glycerolipids. Histological studies revealed a lipid accumulation at cellular level. Lipid bodies surrounded by protein bodies were observed in cotyledonary cells of cold-treated somatic embryos. Furthermore, the cold-treated somatic embryos developed into plantlets with a frequency of 14%, whereas no development was obtained with the non-treated somatic embryos.     

Intensity of lipid peroxidation and concentration of free radicals in quail liver exposed to low-intensity laser irradiation to the embryo

The influence of low level red laser irradiation of Quails japanese embryos on lipid peroxidation level and free radicals concentration in the liver of young quails was estimated. It is detected that irradiation of the embryos in the dose of 15 mJ leads to the significant increase of peroxide lipid level and free radicals contents in the liver of one-day quails. In the liver of three-weeks quails an expressed antioxidant effect of red laser light irradiation of embryos is detected. The decrease of lipid peroxidation products and synthesis of ceruloplasmin in the liver of experimental group poultry confirm it. These changes are accompanied with cytochrome P-450 level increase and don't lead to inhibition of energetic system.     

Developmental fate of the yolk protein lipovitellin in embryos and larvae of winter flounder, Pleuronectes americanus.

The developmental fate of the vitellogenin-derived yolk protein, lipovitellin (Lv), was investigated in winter flounder embryos and yolk-sac larvae. Since Lv is present as only one major polypeptide in ovulated winter flounder eggs, unlike the multiple yolk polypeptides found in the mature eggs of most teleosts, this system is presented as a simpler model of yolk protein structure and utilization during teleostean development. Winter flounder Lv is cleaved during embryogenesis from a 94 kD polypeptide at fertilization to 67 kD and 26 kD polypeptides at hatching. The rate of this proteolytic processing is slow during early embryonic development, but enters a more rapid phase between days 8 and 12 post-fertilization in embryos reared at 4-5 degrees C, and approaches 50% completion at day 10. Lv processing is essentially complete 3 days before hatching; nevertheless, major degradation of the Lv peptide by the developing winter flounder does not occur until after hatching. The Stokes radius of Lv changes only moderately following processing, from 4.50 nm in unfertilized eggs to 4.19 nm in late embryos and newly hatched larvae, whereas the processed Lv retains its heat stability relative to other yolk polypeptides. Nearly 50% of its lipid content, however, is released from the Lv particle during embryogenesis, concomitant with cleavage of the Lv 94 kD polypeptide. Lv processing may thus render a portion of the yolk protein-associated lipid more accessible to the developing embryo, whereas other yolk components are retained for later use by the winter flounder larva. Alternately, removal of lipid may lead to proteolytic vulnerability of the Lv polypeptide. In either case, only a portion of the lipid moiety of the Lv particle appears to play a significant nutritive role for the embryo, whereas its protein component is reserved for larval use. J. Exp. Zool. 284:686-695, 1999.     

Mature and immature synaptosomal membranes have a different lipid composition

Subfractionation of the optic tectum in chick embryos results in the isolation of two fractions enriched in synaptosomes (fraction A and fraction B). In chicks after hatching, this fractionation results in the isolation of a single synaptosomal fraction (fraction B) and of a fraction enriched in myelin membranes devoid of synaptosomes (fraction A). The lipid composition of synaptosomal fractions (A and B) and corresponding synaptosomal plasma membranes has been analyzed and compared to the lipid composition of similar fractions isolated from 2–3 day-old chicks. The phospholipid composition of fraction A in embryos was mainly represented by phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The PE content was significantly lower than that of PC, which accounted for by approximately 50%. Sphingomyelin (SP) and phosphatidylinositol (PI) accounted for by only 6% of the total membrane phopsholipids. Fraction A isolated from the young chicks showed many significant changes. PC accounted for by approximately 40% and PE made up 35%. The amount of phosphatidylserine (PS) and SP increased. These data parallel our previous morphological observations, which showed that fraction A contains immature synaptosomes in embryos but myelin membranes and no synaptosomes in the young chicks. Fraction B has been shown to contain synaptosomes at all stages considered. It possessed in embryos a lipid composition similar to fraction A, except that PC content was higher in young embryos. The analyses on membrane fractions confirmed these results. On the contrary, this fraction showed many significant changes after hatching. The content of PC was significantly reduced, PE/PC ratio was significantly increased as well as ethanolamine plasmalogen (PLE) content. The percentage of PS, PI and SP were increased. The composition of fatty acids of the total fraction of phospholipids was also examined. The results parallel the observations on phospholipid classes.     

Biochemical composition of the Atlantic bonito Sarda sarda from the Aegean Sea (eastern Mediterranean Sea) in different stages of sexual maturity

The content (% wet mass) in water, ash, lipid, crude protein, DNA and RNA of different tissues was determined during sexual maturation of bonitos Sarda sarda from the Aegean Sea. A total of 220 specimens were collected in the following stages of sexual maturity: immature, resting, developing, mature, spawning and spent. Highest lipid levels in the white muscle, red muscle and liver were measured in immature specimens, while lowest levels were found in spawning bonitos. The gradual percentage of lipid reduction from immature to spawning bonitos was relatively higher in the liver (females 71·2% and males 64·4%) than in the white (females 59·2% and males 53·5%) and red (females 62·1% and males 51·7%) muscle. Lipid levels in the gonads increased gradually from the immature to spawning stage. The decrease of lipid in the somatic tissues was more intense in females than in males, and gonadal lipid content was higher in females than in males. There was a strong reverse correlation between water and lipid percentage in all tissues. Protein content decreased significantly only in spawning bonitos. The percentage of protein reduction from immature to spawning stage was relatively higher in males than in females in both white (females 3·4% and males 4·6%) and red (females 4·6% and males 5·1%) muscles. Protein content in the liver was significantly lower than in the other tissues, being highest in mature females. Gonadal protein content in females increased with maturation and decreased after spawning. The content in ash exhibited considerable stability. The RNA:DNA ratio exhibited a similar pattern of variation in both muscles. The RNA:DNA ratio increased during gonadal development gradually from the developing to spent stage. It was concluded that in S. sarda during gonadal development, there was an increase in gonadal lipid accompanied by a decrease in somatic tissue lipid reserves. Thus, reproductive inactive bonitos have more lipid in their edible part and a higher nutritional value than active ones.     

Ultrastructural Studies on Development in Mature Seeds; Embryos of Euonymus europaea L. Dormant or Cultured at +25 ?C

Ultrastructural observations on naturally dispersed and dehydratedseeds of Euonymus europaea L. were performed. It was shown thatduring the culture of isolated embryos at 25 ?C for 7 d thematuration of protein bodies continued; the initial juvenileform (single protein body per cell with dispersed contents)was developing into a more advanced form (single body splitto form several sub-units with condensed contents). Parallelbiochemical determinations pointed to an increase in insolubleprotein levels. There were no changes in other storage organelles,lipid bodies, either in the fine structure or in the level oftriacylglycerols. Deterioration of cellular membranes (in mitochondria,proplastids and protein bodies) similar to that described forageing was observed in cells at the periphery of the embryonicaxis. It is concluded that during the culture of E. europaeaembryos the maturation programme of development in protein bodiesis being continued. Key words: Embryonic axis, storage protein and lipid body, maturation     

Nature of the effect of ther locus on the lipid content of embryos of peas (Pisum sativum L.)

The aim of this work was to discover why pea (Pisum sativum L.) embryos recessive at the r locus (rr) have a higher lipid content than embryos dominant at this locus (RR). The r locus is a gene encoding starch-branching enzyme, rr embryos have a much lower activity of this enzyme than RR embryos, and hence a reduced rate of starch synthesis. The higher lipid content of rr embryos must be a consequence of this. We suggest that neither differences in the availability of substrate for lipid synthesis as a consequence of different rates of starch synthesis, nor differences in the capacity of the pathway for malonyl-CoA synthesis, account for the different lipid contents of RR and rr embryos. Lipid contents of the two sorts of embryo first diverge at a much later stage in development than divergence in starch content. Amounts of pyruvate and acetate, and activities of enzymes that convert triose phosphate to malonyl CoA are the same in the two sorts of embryo. Most of the lipid in developing embryos is polar, structural lipid, and polar lipid accounts for a large proportion of the difference in lipid content between the two sorts of embryo. This difference in structural-lipid content reflects considerable structural differences between the two sorts of embryo and is presumably the consequence of differences in rates of lipid turnover.Abbreviations DW dry weight - FW fresh weight - FAME fatty-acid methyl esters This work was supported by a grant-in-aid from the Agricultural and Food Research Council to the John Innes Institute. We are very grateful to Alan Jones for his valuable advice on lipid analysis and to Dr. Kay Denyer (Advanced Technologies, Cambridge, UK) for valuable discussions. We thank Dr. Cliff Hedley for the gift of the seed of the peas used in this work.     

Water Content, Raffinose, and Dehydrins in the Induction of Desiccation Tolerance in Immature Wheat Embryos

Desiccation tolerance is initiated in wheat (Triticum aestivum L.) embryos in planta at 22 to 24 d after anthesis, at the time that the embryo water content has decreased from about 73% fresh weight (2.7 g water/g dry weight) to about 65% fresh weight (1.8 g water/g dry weight). To determine if desiccation tolerance is fully induced by the loss of a relatively small amount of water, detached wheat grains were treated to reduce the embryo water content by just a small amount to approximately 69% (2.2 g water/g dry weight). After 24 h of such incipient water loss, subsequently excised embryos were able to withstand severe desiccation, whereas those embryos that had not previously lost water could not. Therefore, a relatively small decrease in water content for only 24 h acts as the signal for the development of desiccation tolerance. Embryos that were induced into tolerance by a 24-h water loss had no detectable raffinose. The oligosaccharide accumulated at later times even in embryos of detached grains that had not become desiccation tolerant, although tolerant embryos (i.e. those that previously had lost some water) contained larger amounts of the carbohydrate. It is concluded that desiccation tolerance and the occurrence of raffinose are not correlated. Immunodetected dehydrins accumulated in embryos in planta as desiccation tolerance developed. Detachment of grains induced the appearance of dehydrins at an earlier age, even in embryos that had not been made desiccation tolerant by incipient drying. It is concluded that a small reduction in water content induces desiccation tolerance by initiating changes in which dehydrins might participate but not by their interaction with raffinose.     

Water content, lipid deposition, and (+)-abscisic acid content in developing white spruce seeds

Whole seeds, and isolated megagametophytes, seed coats and embryos from white spruce [Picea glauca (Moench) Voss] were used to monitor water distribution by magnetic resonance microimaging, lipid composition by gas chromatography, and (+)-abscisic acid content ((+)-ABA) by enzyme-linked immunsorbent assay, during seed development. The highest (+)-ABA content was detected in the female gametophytic tissue, this at 11 d after pollination (DAP). Reserve deposition was evident up to 59 DAP in the female gametophyte and in the developing embryo. The maturation drying period occurred between 59 DAP and 93 DAP. At 59 DAP, the seed contained 24% water (gwater/gwet weight), and within a 34 d period, the water content declined to 6% water (gwater/gwet weight). (+)-ABA concentrations in developing seeds varied between 10 and 31 M. The decrease in water content accounted for the higher (+)-ABA concentrations.     

Ultrastructural changes in wheat embryos during a “presowing drought hardening” treatment

Summary Changes in the ultrastructure of the shoot apex of wheat embryos were studied during a reputed drought hardening treatment consisting of 48 hours of hydration followed by dehydration to air dry weight and during a subsequent second hydration for 48 hours. In the initial dry state lipid droplets are closely packed against the cell walls and the mitochondria and plastids have little internal structure. During the first hydration the lipid droplets are reduced in number and disperse while the mitochondria and plastids assume a normal appearance. The nucleus does not change appreciably. Under the conditions used in this work dehydration to air dry weight is not lethal to the embryos although notable changes in cellular structure occur: 1. Massive condensation of the normally loosely organized chromatin, 2. some loss of internal mitochondrial structure, 3. specific association of short elements of rough ER with vacuoles and lipid droplets, and 4. formation of fibrillar elements in the cytoplasm. In some respects then, embryos dehydrated after a 48 hour soaking have a very different structure to that of embryos that have dried during maturation of the seed. Since these changes are, in the case of viable embryos, reversible upon rehydration they cannot be linked, as such, to any long term drought hardening effect of the treatment. It is suggested that some changes, particularly the condensation of chromatin, may indicate a protective response to water stress. The kind of information needed to sustain this suggestion is discussed.This project is supported by grants from the Rural Credits Development Fund and the Australian Research Grants Committee.     

Lipid and fatty acid composition during embryo and larval development of puye Galaxias maculatus Jenyns, 1842, obtained from estuarine, freshwater and cultured populations

Galaxias maculatus eggs and larvae obtained from broodfish captured either in an estuarine or a freshwater environment, as well as from cultured broodstock were analysed to compare their lipid and fatty acid profiles. Results showed a lower lipid content in embryos and larvae from estuarine populations than those from fresh water, denoting the influence of environmental conditions. The n-3:n-6 ratio was higher in eggs from estuarine and cultured populations, being in the range of marine fishes, whereas for eggs from freshwater fish was lower and typical of freshwater fishes. The polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (22:6n-3) and eicosapentaenoic acid (20:5n-3), were higher in eggs and larvae of broodstock coming from culture or estuarine environments than in those from fresh water. Moreover, these fatty acids markedly increased after hatching in larvae coming from estuarine populations, suggesting the effect of the environment on fatty acid profiles to physiologically prepare the larvae to adapt to higher salinity conditions. Linoleic acid (18:2n-6) content was higher in fresh water fish and its reduction during embryo and larval development was accompanied by a significant increase of arachidonic acid (20:4n-6), which was not observed in embryos or larvae from broodstock fish from estuary or aquaculture origin. Both environment and diet of broodstock fish affected lipid and fatty acid composition of G. maculatus embryo and larvae as well as their changes during development.     

Organic,inorganic, and caloric composition of eggs,pentaculae, and adults of the brooding sea cucumber Cucumaria curata cowles (Echinodermata: Holothuroidea)

Levels (percentage composition) of water, ash, carbohydrate, lipid, protein, and calories were determined for eggs, pentaculae, and adults of the sea cucumber Cucumaria curata Cowles. Component contents (μg/individual) were calculated for eggs and pentaculae. During the 28 days of development to hatching, the large yolky eggs gain water and ash, the total dry weight increasing from 169 to 190 μg/egg during embryogenesis. There were no statistically significant changes in lipid, protein, and caloric contents during embryogenesis, but carbohydrate decreased by 0.82 μg/egg.The decrease in carbohydrate is sufficient to account for estimated embryonic energy requirements. Based on the utilization of carbohydrate, embryos of C. curata show a nutritional pattern similar to that of the planktonic embryos of sea urchins and different from that of embryos developing from terrestrial eggs, freshwater eggs, and planktonic and demersal marine eggs.Although broods varied widely in egg number and mean egg dry weight, C. curata gives eggs which contain a constant proportion of organic components.Levels of ash, water, and protein in the adults exceeded those in the pentacula, and lipid comprises a much smaller proportion of the adult body than it did of the pentacula.     

Comparative assessment of chelated spent mushroom substrates as casing material for the production of Agaricus bisporus

Spent mushroom substrate (SMS) leached with water or treated with chelating agents to remove metal cations, pasteurised to remove any harmful micro-organisms and mixed with peat has potential as a casing material for mushroom production. The microbial and chemical changes in SMS after treatment with citric acid, ethylene diaminetetraacetic acid (EDTA) and water were compared; treatment with the chelating agents resulted in lower ash content, conductivity and minerals, higher fibre fractions, carbon, hydrogen and nitrogen. The microbial and chemical changes in the materials after treatment with the two chelators and water were compared. Blending peat with the heat-treated materials at a ratio of 1:1 resulted in improved physical properties. The casings prepared from the test materials and the control, consisting of 100% peat, were compared after neutralising with lime for their productivity in a mushroom yield trial. As expected, the compost bags cased with the control were the most productive compared to the other casings. Of the three treated materials, casing prepared from SMS treated with EDTA blended with peat was the most productive. Dry matter of harvested mushrooms from chelated-SMS casings was significantly higher than the control casing. Comparison of the main components of peat and chelated SMS revealed that the major differences were in the proportions of ash, lipid, lignin and fibre fractions. The stability of some of these components, when complexed with metal cations present in lime may play an important role in determining the composition of the cell wall in fruiting bodies leading to high dry matter content. Received: 19 November 1998 / Received revision: 29 March 1999 / Accepted: 6 April 1999     

Salt leaching leads to drier soils in disturbed semiarid woodlands of central Argentina

Disturbances in semiarid environments have revealed a strong connection between water, salt and vegetation dynamics highlighting how the alteration of water fluxes can drive salt redistribution process and long-term environmental degradation. Here, we explore to what extent the reciprocal effect, that of salt redistribution on water fluxes, may play a role in dictating environmental changes following disturbance in dry woodlands. We assessed salt and water dynamics comparing soil-solution electrical conductivity, chloride concentration, soil water content (SWC) and soil matric and osmotic water potential (Ψ_m, Ψ_os) between disturbed and undisturbed areas. A large pool of salts and chlorides present in undisturbed areas was absent in disturbed plots, suggesting deep leaching. Unexpectedly, this was associated with slight but consistently lower SWC in disturbed versus undisturbed situations during two growing seasons. The apparent paradox of increased leaching but diminishing SWC after disturbance can be explained by the effect of native salt lowering Ψ_os enough to prevent full soil drying. Under disturbed conditions, the onset of deep drainage and salt leaching would raise Ψ_os allowing a decline of Ψ_m and SWC. Soil water storage seems to be modulated by the presence (under natural conditions) and partial leaching (following selective shrub disturbance) of large salt pools. This counterintuitive effect of disturbances may be important in semiarid regions where deep soil salt accumulation is a common feature. Our results highlight the importance of water–salt–vegetation coupling for the understanding and management of these systems.     

Cytological and physiological changes in recalcitrant Chinese fan palm (<Emphasis Type="Italic">Livistona chinensis</Emphasis>) embryos during cryopreservation

Cytological and physiological changes during cryopreservation were investigated in Livistona chinensis embryos excised 42 weeks after flowering. Both dehydration and freezing caused numerous cellular ultrastructural alterations. Dehydration seriously impaired plasma membrane integrity, while freezing caused a further increase in electrolyte leakage. Damage to cellular ultrastructure and plasmalemma integrity had an inverse relationship with water content in unfrozen embryos and a positive relationship in frozen embryos. Changes in activity of antioxidant enzymes differed during cryopreservation. Dehydration and freezing had little effect on superoxide dismutase activity, although these treatments greatly reduced embryo viability. Activity of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) changed only slightly during dehydration, but dehydration markedly decreased activity of ascorbate peroxidase (APX) and catalase (CAT). Freezing further decreased APX and GR activity but increased CAT activity in dehydrated samples. A novel DHAR isozyme was induced during the freeze–thaw cycle. Membrane lipid peroxidation was detected in the control embryos, and was promoted by both dehydration and freezing. The malondialdehyde (MDA) content in post-thaw embryos increased by a maximum of 30%. Thus, changes in viability of embryos were closely related to damage to cellular ultrastructure and plasmalemma integrity, but were not directly related to antioxidant activity nor MDA accumulation.     

Fatty acid composition of phospholipids in mitochondria and microsomes during diethylnitrosamine carcinogenesis in rat liver

Changes in lipid composition and function of subcellular organelles have been described in transplanted and primary tumours. We examine here the fatty acid composition of individual phospholipids (PL) in hyperplastic nodules and primary hepatoma induced by diethylnitrosamine (DEN), compared to that of normal liver and of transplantable Yoshida AH-130 hepatoma. Phosphatidylcholine and phosphatidylethanolamine fatty acid composition in mitochondria and microsomes from primary hepatoma were markedly different from normal liver; C18:0/C18:1 ratio was lower and the ratio between monosaturated and polyunsaturated fatty acids was higher. Linoleic acid content of mitochondrial cardiolipin, usually very high in normal rat liver, was notably lower in primary hepatoma. Cholesterol/phospholipid ratio in both microsomes and mitochondria from DEN-induced hepatoma was higher than in normal liver. Hyperplastic nodules showed no changes in cholesterol content whereas modifications in fatty acid composition were already observable. These modifications of membrane structure may be related to the functional changes found in nodular cells. Changes in fatty acid composition of membrane phospholipids, occurring in both primary hepatoma and preneoplastic nodules, might be one of the causes for decreased rate of lipid peroxidation peculiar to these tissues.