Research Progress of Fatty Acid Desaturase 2 Gene in Glycolipid Metabolism / 中国医学科学院学报

The fatty acid desaturase 2 (FADS2) gene encodes delta-6 desaturase (D6D) and is a member of the fatty acid desaturase gene family.D6D is the key enzyme catalyzing the transformation of linoleic acid and α-linolenic acid to long-chain polyunsaturated fatty acid (LC-PUFA).LC-PUFA play a crucial role in regulating the glycolipid metabolism of living organisms.In recent years,the activity of D6D and the single nucleotide polymorphism (SNP) of FADS2 gene have become a hot topic in the research on glycolipid metabolism.This article reviews the role of FADS2 gene in glycolipid metabolism.

Achados oftalmológicos na doença de Gaucher tipo III: caso clínico / Ophthalmologic findings in Gaucher's disease type III: case report

Resumo Relata-se um caso de uma paciente com doença de Guacher tipo III, com mutação no Exon9, 1246G>A e 1251G>C, buscando investigar a suspeita de glaucoma, descrever os achados oftalmológicos, como acumulo de glicolipideo em região pré- retiniana e investigar a possível correlação com a diminuição da camada de fibras nervosas.

Abstract We report a case of a patient with Guacher's disease type III, with mutation in Exon9, 1246G> A and 1251G> C, seeking to investigate the suspected glaucoma, to describe the ophthalmological findings, as glycolipid accumulation in the pre-retinal region and to investigate The possible correlation with the decrease of the layer of nerve fibers.

Biosurfactant production by Pseudomonas aeruginosain kefir and fish meal

The aim of this study was to increase rhamnolipid production by formulating media using kefir and fish meal for Pseudomonas aeruginosa strains isolated from different environmental resources. The strains, named as H1, SY1, and ST1, capable of rhamnolipid production were isolated from soil contaminated with wastes originating from olive and fish oil factories. Additionally, P. aeruginosa ATCC 9027 strain, which is known as rhamnolipid producer, was included in the study. Initially, rhamnolipid production by the strains was determined in Mineral Salt Medium (MSM) and then in media prepared by using kefir and fish meal. The obtained rhamnolipids were purified and quantified according to Dubois et al. (1956). The quantity of rhamnolipids of ATCC, H1 and SY1 strains in kefir media were determined as 11.7 g/L, 10.8 g/L and 3.2 g/L, respectively, and in fish meal media as 12.3 g/L, 9.3 g/L and 10.3 g/L, respectively. In addition, effect of UV light exposure on rhamnolipid production was also investigated but contrary a decrease was observed. The results indicate that P. aeruginosa strains isolated from various environmental resources used in this study can be important due to their rhamnolipid yield, and fish meal, which is obtained from waste of fish, can be an alternative source in low cost rhamnolipid production.

Best conditions for biodegradation of diesel oil by chemometric tools

Diesel oil biodegradation by different bacteria-yeast-rhamnolipids consortia was tested. Chromatographic analysis of post-biodegradation residue was completed with chemometric tools (ANOVA, and a novel ranking procedure based on the sum of ranking differences). These tools were used in the selection of the most effective systems. The best results of aliphatic fractions of diesel oil biodegradation were observed for a yeast consortia with Aeromonas hydrophila KR4. For these systems the positive effect of rhamnolipids on hydrocarbon biodegradation was observed. However, rhamnolipids addition did not always have a positive influence on the biodegradation process (e.g. in case of yeast consortia with Stenotrophomonas maltophila KR7). Moreover, particular differences in the degradation pattern were observed for lower and higher alkanes than in the case with C22. Normally, the best conditions for "lower" alkanes are Aeromonas hydrophila KR4 + emulsifier independently from yeasts and e.g. Pseudomonas stutzeri KR7 for C24 alkane.

In situ biosurfactant production and hydrocarbon removal by Pseudomonas putida CB-100 in bioaugmented and biostimulated oil-contaminated soil

In situ biosurfactant (rhamnolipid) production by Pseudomonas putida CB-100 was achieved during a bioaugmented and biostimulated treatment to remove hydrocarbons from aged contaminated soil from oil well drilling operations. Rhamnolipid production and contaminant removal were determined for several treatments of irradiated and non-irradiated soils: nutrient addition (nitrogen and phosphorus), P. putida addition, and addition of both (P. putida and nutrients). The results were compared against a control treatment that consisted of adding only sterilized water to the soils. In treatment with native microorganisms (non-irradiated soils) supplemented with P. putida, the removal of total petroleum hydrocarbons (TPH) was 40.6%, the rhamnolipid production was 1.54 mg/kg, and a surface tension of 64 mN/m was observed as well as a negative correlation (R = -0.54; p < 0.019) between TPH concentration (mg/kg) and surface tension (mN/m), When both bacteria and nutrients were involved, TPH levels were lowered to 33.7%, and biosurfactant production and surface tension were 2.03 mg/kg and 67.3 mN/m, respectively. In irradiated soil treated with P. putida, TPH removal was 24.5% with rhamnolipid generation of 1.79 mg/kg and 65.6 mN/m of surface tension, and a correlation between bacterial growth and biosurfactant production (R = -0.64; p < 0.009) was observed. When the nutrients and P. putida were added, TPH removal was 61.1%, 1.85 mg/kg of biosurfactants were produced, and the surface tension was 55.6 mN/m. In summary, in irradiated and non-irradiated soils, in situ rhamnolipid production by P. putida enhanced TPH decontamination of the soil.

Enhanced crude oil biodegradation and rhamnolipid production by Pseudomonas stutzeri strain G11 in the presence of Tween-80 and Triton X-100.

In this study, the growth of sixty-one bacterial strains in crude oil were determined spectrophotometrically at 620 nm. Pseudomonas aeruginosa G1, Pseudomonas fluorescens G6, Pseudomonas stutzeri G11 and Pseudomonas putida G15 were chosen for the study based on the efficiency of crude oil utilisation. At 1% (v/v) crude oil concentration, P. stutzeri G11 strain degraded a maximum of 69%. The percentage of degradation by the P. stutzeri G11 strain decreased from 69% to 59% as the concentration of crude oil was increased from 1% (v/v) to 2.5% (v/v). Strain G11 was selected to determine the effects of surfactants (Tween-80 and TritonX-100) on the biodegradation of crude oil. While strain G11 showed 76% degradation at mineral salts medium (MSM) containing 1% (v/v) crude oil + 1% (v/v) TritonX-100, it showed 61% degradation at MSM containing 2.5% (v/v) crude oil + 2.5% (v/v) TritonX-100. Also, degradation rate of this strain was 96% in the presence of 1% (v/v) crude oil + 1% (v/v) Tween-80, while degradation rate was 48% in the presence of 25% (v/v) crude oil+ 2.5% (v/v) Tween-80. Additionally, we investigated the rhamnolipid production of P. stutzeri G11 strain both in crude oil and in crude oil + two different surfactants (TritonX-100 and Tween-80, separately). These results suggest that surfactants have improved both crude oil degradation and rhamnolipid production and the degradation rates have depended very much on the chemical structure of surfactants.

Morphological and functional characterizations of Schwann cells stimulated with Mycobacterium leprae

Nerve damage, a characteristic of leprosy, is the cause of patient deformities and a consequence of Schwann cells (SC) infection by Mycobacterium leprae. Although function/dysfunction of SC in human diseases like leprosy is difficult to study, many in vitro models, including SC lines derived from rat and/or human Schwannomas, have been employed. ST88-14 is one of the cell lineages used by many researchers as a model for M. leprae/SC interaction. However, it is necessary to establish the values and limitations of the generated data on the effects of M. leprae in these SC. After evaluating the cell line phenotype in the present study, it is close to non-myelinating SC, making this lineage an ideal model for M. leprae/SC interaction. It was also observed that both M. leprae and PGL-1, a mycobacterial cell-wall component, induced low levels of apoptosis in ST88-14 by a mechanism independent of Bcl-2 family members.

Production of glycolipids containing biosurfactant by Pseudomonas species.

Microorganisms, that degrade hydrocarbon were isolated and screened for their biosurfactant activity. A total of 68 strains were isolated and tested for their glycolipid activity of which 4 isolates showed good glycolipid activity. Isolate K10 gave the maximum biosurfactant production in medium A (containing kerosene as a sole carbon source) as compared to medium B (containing glucose as a sole carbon source). Characterization of isolate K10 showed that it belongs to Pseudomonas species.

Danazol-induced biochemical changes in the rat ovary.

Effect of varying doses of danazol, a synthetic steroid derivative of 17 alpha-ethinyl testosterone has been observed on the biochemistry of the rat ovary. Biochemically total proteins decreased and total lipids increased with the danazol treatment. Triglycerides, the stored form of lipids formed the major components of lipids in the treated ovaries. The amount of phospholipids, glycolipids, cholesterol and free fatty acids decreased in the ovaries with increased danazol treatment. The functional significance of these changes have been discussed with ovarian physiology especially in relation to follicular growth and atresia.

Specific binding of Burkholderia pseudomallei cells and their cell-surface acid phosphatase to gangliotetraosylceramide (asialo GM1) and gangliotriaosylceramide (asialo GM2).

Specific binding between bacterial cells and host tissue is an early step of the pathogenesis of infection. Burkholderia pseudomallei cells, the causative micro-organisms of melioidosis, were demonstrated to bind specifically to tissue glycolipids (asialo GM1 and asialo GM2) by solid phase binding assay on thin layer chromatograms. The detection limit was around 400 pmol of the glycolipids. Acid phosphatase purified from the culture filtrate of B. pseudomallei was tested for such binding properties, and the same results were obtained. According to our previous studies, the enzyme is a glycoprotein located on the cell surface, and hydrolysed tyrosine phosphate most actively among the substrates so far tested. The mode of binding between the enzyme and the glycolipids was analyzed by comparison of binding levels among three samples different in protein content, sugar content and specific phosphatase activities per protein and sugar residue. The results suggested the possibility of a receptor-ligand relationship between the bacterial enzyme and the host-cell glycolipids (asialo GM).

Effect of ethanol on glycerolipid and faty acid metabolism in Hep G2 human-hepatoma cells

It is well-known that ethanol alters fatty acid and glycerolipid metabolism in liver, but most of the studies have been deleloped on rats, so little known about the corresponding effects on human liver. We have chosen the Hep G2 human hepatoma cell line, which appears be an excellent in vitro model system. Cells were incubated in ethanol containing medium (0-400 mM) for 48 h. Incorporation and metabolism of radioactive substrates (14C(U) glycerol, [1-(14)C] palmitic acid and [1-(14)C] eicosatrienoic acid (n-6) were analyzed in cellular and conditioned medium lipids. Cellular growth rate and lipid composition of control and ethanol-treated cells were also studied. The results showed that ethanol inhibited logarithmic cellular growth rate in a concentration dependent manner, without affecting viability. Ethanol (400 mM) did not modify cellular major lipid composition except for an increase of cholesteryl esters, but produced a decrease in the proportions of myristic, palmitic and palmitoleic acids. Ethanol enchanced the incorporation of radioactive fatty acids into cellular glycerolipids but did not alter the rate of incorporation of 14C(U) glycerol. This was attributed to an isotopic solution of the radioactive glycerol as a result of increasde alfa-glycerophosphate biosynthesis. Incorporation of radioactive fatty acids and glycerol into conditioned medium glycerolipids were increased in cells incubated in presence of ethanol. The increased incorporation of 14C glycerol into conditioned medium together with a simultaneous diminuition in labeling cellular glycerides suggest that there would be a simulation of the export of these lipid classes to conditioned medium. Conversion of [1-(14)C] palmitic to oleic acid and eicosatrienoic to arachidonic acid were inhibited in 400 mM ethanol treated cells suggesting an inhibition of delta 9 and delta 5 desaturase activity.

Signal transduction in host cells mediated by glycosylphosphatidylinositols of the parasitic protozoa, or why do the parasitic protozoa have so many GPI molecules?

Considerable circumstantial evidence indicates that glycosylphosphatidylinositol (GPI) molecules of mammalian origin are able to mediate signal transduction in lymphoid cells. For example, pertubation of GPI-anchored surface proteins, but not transmembrane forms of these molecules, can lead to the activation of T lymphocytes. GPIs appear also to be precursors of pharmacologically active phosphoinositol-glycans which mediate responses to hormones such as insulin, nerve growth factor and IL-2. Nonetheless, the biochemical mechanisms of signal transduction by GPIs remain obscure. We have shown that structurally defined GPIs of protozoal parasite origin are able to mediate signal transduction in host macrophages and lymphocytes, by substituting for the putative endogenous GPI-based signalling mechanisms of the host. Signalling by parasite GPIs appears to involve the activation of protein tyrosine kinase and protein C. Evidence from other sources indicates that structurally variant GPIs may provide anergic signals to down-regulate host cell function. These phenomena may represent mechanisms by which eukaryotic parasites regulate host cell function, and can explain a variety of pathological and immunological features of protozoal infections. Furthermore, protozoal GPIs may prove to be an informative model system for the analysis of GPI-mediated signal transduction in lymphocytes and macrophages

Early molecular signals induced by antibodies to GPI-anchored proteins

We have examined intracellular biochemical and metabolic changes induced by antibodies specific for glycosylphosphatidylinositol (GPI)-anchored cell surface molecules. In lymphoid cells the earliest detectable responses are phosphorylation of intracellular substrates. The GPI-linked target antigens are also rapidly redistributed into patches and caps on the cell surface and then internalised. Between two and five hours later, cytokine receptors are expressed. Later, cells become metabolically active and begin to proliferate and express endogenous cytokines, thus promoting autocrine growth. Very early events, such as kinase activity, are induced by antibody binding alone and are characteristic of the cell surface molecule recognised by antibodies. Thus, the initial events in the activation cascade are critical in selecting the metabolic route. Progression down the activation cascade requires further signals such as cross-linking antibodies, exogenous cytokines, phorbol esters, or accessory cells. Once in cycle, cells no longer display evidence of their original route of activation. Activated T lymphocytes acquire resitance to cleavage by GPI-specific phospholipase C, suggesting a possible feedback mechanism to limit cell proliferation

Characterisation of phosphoprotein complexes associated with rat thymocyte Thy-1

We have previously demonstrated the non-covalent association of the protein tyrosine kinases p56lck and p60fyn together with a number of substrates for phosphorylation with rat thymocyte Thy-1. Here we present evidence that one of these associated phosphoproteins, p85, is associated by disulphide bridging with another polypeptide, demonstrating that it is an integral membrane protein with an extracellular domain. We also show that phosphatidylinositol 3 kinase activity may be coprecipitated with Thy-1 in Brij 96 thymocyte lysates

The fate of GPI-anchored molecules

Glycosylphosphatidylinositol (GPI)-anchored proteins comprise a diverse class of membrane molecules. They protect cells from complement-mediated lysis, control cell to cell adhesion, activate T cells, and play a role in the etiology of slow viral diseases. Despite their functional diversity, GPI-anchored proteins are all attached to the plasma membrane by a common glycolipid anchor. We will examine one aspect of GPI-anchor metabolism, namely, the processing of the molecule after it arrives at the plasma membrane. After biosynthesis and transport to the plasma membrane, the GPI-anchored protein can be endocytosed and degraded or cleaved and released. The enzymatic machinery controlling the catabolism of GPI-anchored molecules at the plasma membrane is likely to play a central role in regulating the cell surface expression of these molecules

The tails of two proteins: the scrapie prion protein and the ciliary neurotrophic factor receptor

Many proteins with a variety of functions have proven to have glycosylphosphatidylinositol (GPI)-linkages; two members of this family are the scrapie prion protein and the receptor for ciliary neurotrophic factor (CNTF). The scrapie prion protein has two isoforms: PrPC is found in brain cells from normal animals, while PrPsc is an abnormal isoform that is only found in scrapie-infected animals. PrPsc is the only identified component of the prion, an infectious agent that apparently does not contain nucleic acid. Models for how prions replicate require that PrPsc must somehow recruit PrPC and catalyze or stabilize a post-translational event that converts PrPC into PrPsc. Extensive characterization has suggested that this critical post-translational event is probably conformational and not a chemical change. The presence of a GPI anchor on CNTFRalfa is an unusual feature for a molecule that must transmit a signal to the inside of the cell. Recent data have indicated that CNTFRalfa must bind CNTF, then interact with two other "ß" receptor components to initiate signal transduction. Furthermore, we have shown that, unlike the vast majority of receptors, CNTFRalfa can function as a soluble molecule to promote CNTF action on cells that contain the two ß components, but do not themselves express CNTFRalfa. Intringuingly, we have also demostrated that CNTFRalfa is present in cerebrospinal fluid and blood in vivo, and the release of CNTFRalfa from skeletal muscle is increased by denervation of the muscle. Whether the soluble form is released through GPI-anchor cleavage remains to be determined

Intracellular transport of GPI-anchored proteins by yeast

We have investigated the effects of an inhibitor of ceramide biosynthesis on the glycosylphosphatidylinositol (GPI)-anchoring and intracellular transport of the yeast Gas 1 protein. No effect on anchor attachment was demonstrable, but a selective delay in transport from the endoplasmic reticulum to the Golgi complex was observed. The compound also blocked remodeling of GPI-anchors from their base-sensitive to base-resistant forms. A recessive mutation was found that caused resistance to the drug, restored transport of Gas 1p, but did not restore ceramide biosynthesis in the presence of the inhibitor. Our results suggest that intracellular transport of GPI-anchored proteins is stimulated by new ceramide synthesis. The role of ceramide may be direct or may be through its use in the remodeling of GPI-anchored proteins other than Gas 1p. The need for ceramide can be overcome in the mutant strain

Malaria parasites: enzymes involved in red blood cell invasion

Three enzymes have been described in malaria merozoites: a serine-protease and two phospholipases. The parasite serine-protease is necessary for parasite entry into the red blood cell. This enzyme is synthesized by intraerythrocytic schizonts as a glycolipid-anchored membrane precursor, harbouring a performed serine-protease active site but not detectable proteolytic activity. Detection of the enzymatic activity correlates with the solubilisation of the enzyme by a parasite glycolipid-specific phospholipase C in merozoites. A third enzyme has been detected with glycolipid-degrading activity, presumably a lipase A. These activities participate in a biochemical cascade originating with the attachment of the merozoite to the red blood cell, including the translocation of the phospholipase C to the membrane-bound protease, the solubilisation/activation of the protease and its secretion at the erytrocyte/parasite junction and ending with the entry of the parasite into the host cell. Both the phospholipase C and the lipase A might generate secondary messages in the merozoite. Our current knowledge concerning these enzymes is presented

GPI-specific phospholipase D as an apolipoprotein

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) has recently been shown to be associated with high-density lipoproteins (HDL) in bovine serum. To determine the distribution of GPI-PLD among lipoproteins and characterize the GPI-PLD-containing lipoproteins in human plasma, we used dextram sulfate and immunoaffinity chromatography to isolate apolipoprotein-specific lipoproteins. This procedure allowed fractionation of lipoprotein particles into those containing apolipoprotein B (Lp B), apolipoproteins AI and AII (Lp AI/AII), or apolipoprotein AI only (Lp AI). In five plasma samples with HDL cholesterol ranging from 40 to 129 mg/dl, 75 ñ 12 percent (mean ñ SD) of the GPI-PLD activity was associated with LpAI, 11 ñ 13 percent with Lp AI/AII, while only 13 ñ 9 percent was present in plasma devoid of these lipoproteins, suggesting that most of the GPI-PLD in human plasma is associated with apolipoprotein AI. No GPI-PLD activity was detected in Lp B. Further characterization of the GPI-PLD-containing lipoproteins by gel filtration chromatography, nondenaturing poly-acrylamide and agarose gel electrophoresis revealed that GPI-PLD was restricted to an apolipoprotein AI-containing particle or complex that was small (apparent mean Mw of 140 KDa) and distinct from the bulk of HDL. Thus, the majority of plasma GPI-PLD appears to be specifically associated with a small, minor fraction of apoloprotein AI

The role of glycolipid C in the GPI biosynthetic pathway in Trypanosoma brucei bloodstream forms

The glycosylphosphatidylinositol (GPI) biosynthetic pathway in Trypanosoma brucei bloodstream forms includes the formation of glycolipid C. This molecule is the inositol-acylated form of the GPI anchor precursor, glycolipid A. There is no evidence for the transfer of glycolipid C to protein in vivo and the role of glycolipid C is unclear. In this paper we show that glycolipid C is not synthesised in the presence of phenylmethylsulphonyl fluoride (PMSF) and that glycolipid C is not an obligatory intermediate on the pathway to the formation of glycolipid A. Using pulse-chase experiments we show that glycolipid A and glycolipid C are in a dynamic equilibrium and we suggest that only the forward reaction (glycolipid A conversion to glycolipid C) is inhibited by PMSF