Characterization of floating microplastic contamination in the bay of Marseille (French Mediterranean Sea) and its impact on zooplankton and mussels

Microplastics (MPs) were sampled in three seasons from 2016 to 2018 in the Bay of Marseille, northwestern Mediterranean Sea, adjacent to a highly urbanized area. Six sites were selected according to their different characteristics (river mouth, treatment plants, protected marine area). Surface floating MPs were characterized (number, weight, typology and polymer) as was zooplankton. In addition, mussels were submerged and used to investigate ingestion. Finally, a hydrodynamic model was used to improve understanding of dispersion mechanisms. The annual averages of floating MPs values ranged from 39,217 to 514,817 items/km². The MPs collected were mainly fragments principally composed of polyethylene and polypropylene. The mean abundance ratio (MPs/zooplankton) was 0.09. On average 87% of mussel pools were contaminated and ingested 18.73 items/100 g of flesh. Two hydrodynamic patterns were identified: the first retaining the MPs in the harbor, and the second dispersing them outside.

Earthquakes and extreme rainfall induce long term permeability enhancement of volcanic island hydrogeological systems

Earthquakes affect near-surface permeability, however temporal permeability evolution quantification is challenging due to the scarcity of observations data. Using thirteen years of groundwater level observations, we highlight clear permeability variations induced by earthquakes in an aquifer and overlaying aquitard. Dynamic stresses, above a threshold value PGV > 0.5 cm s⁻¹, were mostly responsible for these variations. We develop a new model using earth tides responses of water levels between earthquakes. We demonstrate a clear permeability increase of the hydrogeological system, with the permeability of the aquifer increasing 20-fold and that of the aquitard 300-fold over 12 years, induced by fracture creation or fracture unclogging. In addition, we demonstrate unprecedented observations of increase in permeability due to the effect of extreme tropical deluges of rainfall and hurricanes. The water pressure increase induced by the exceptional rainfall events thus act as piston strokes strong enough to unclog congested fractures by colloids, particles or precipitates. Lastly, an analysis of regional permeabilities also highlights a permeability increase over geological timeframes (× 40 per million years), corroborating the trend observed over the last decade. This demonstrates that permeability of aquifers of andesitic volcanic islands, such as the Lesser Antilles, significantly evolve with time due to seismic activity and extreme rainfall.

Purification, product characterization and kinetic properties of lipoxygenase from olive fruit (Olea europaea L.)

Lipoxygenase from olive fruit was purified to homogeneity for the first time after differential centrifugations and by hydrophobic chromatography. The enzyme had a molecular mass of 98 kDa and exhibited a maximal activity at pH 6. Lipoxygenase had a better affinity for linoleic acid (Km=82.44 microM) than for linolenic acid (Km = 306.26 microM). It is inhibited by linoleate:oxygen oxidoreductase (LOX) inhibitors like nordihydroguaiaretic acid (NDGA) or propyl gallate. The reaction product was 13-hydroperoxy octadecadienoic acid when linoleic acid was used as substrate.

Conception and characterization of a dual-concentric-core erbium-doped dispersion-compensating fiber

We present an erbium-doped dispersion-compensating fiber made up of two asymmetric concentric cores, inner and outer matched claddings, and erbium located in the central core only. We demonstrate a high negative chromatic dispersion value [-700 ps/(nm km) at 1568 nm], significant modification of the gain spectrum compared with that of a classic erbium-doped fiber amplifier, and 30-dB peak small-signal gain at 1535 and 1553 nm.

Anti-U-like: a common antibody in Black individuals

BACKGROUND AND OBJECTIVES

Anti-Uz, a scarce antibody, defines a glycophorin B high-incidence antigen, which is protease-sensitive. In a few years, we have encountered 12 antibodies of similar specificity, made by Black individuals of the S- s+ U+ phenotype.

MATERIALS AND METHODS

Antibodies were characterized by serological methods, with common and rare MNS types, as well as red cells treated with various proteases.

RESULTS

Anti-U-like, mostly an autoantibody, was of IgG class and reacted optimally by indirect antiglobulin test at 20 degrees C. The corresponding antigen was destroyed by several proteases. Tests with papain-treated or Dantu+ cells suggested the existence of several subspecificities.

CONCLUSION

Anti-U-like is common in the African population, though its reactions are often misinterpreted. The fact that antibody producers are always Black patients remains unexplained. No relationship with a pathological state could be established.

Mitochondrial DNA variation and RAPD mark oleasters, olive and feral olive from Western and Eastern Mediterranean

The study of genetic diversity within the olive-tree (cultivated and wild forms) may be useful to reveal agronomic traits in the wild germplasm and to try to understand the history of the olive-tree domestication. In this way, a study of nuclear and mitochondrial DNAs of cultivated and wild olives from two Corsican and Sardinian Mediterranean islands was performed using RAPD and RFLP markers. Our results show that most of the varieties and most of the oleasters were separated using the UPGMA dendrogram based on the Nei and Li similarity index. Most of oleasters carried either the MOM or MCK mitotype, characteristic of olives in the Western Mediterranean, whereas most of the varieties carried the ME1 mitotype, characteristic of olives in the East Mediterranean. The results indicate that the combination of mitotype and RAPD markers can be used as a powerful tool for differentiating two groups in the wild forms: the Western true oleasters and the feral forms. The true oleasters are characterized by a Western mitotype and a Western RAPD pattern. Feral forms originate either from varieties or from hybridisation between a variety and an oleaster. Consequently, as expected, some of them aggregated with the varieties from which they were derived. The other feral forms are clustered with the oleasters and were detected only by their mitotype determination. This study has also permitted us to differentiate two populations of cultivated olives in Corsica: one with close relationships with Italian varieties (influenced by the East) and one selected from local oleasters probably due to a better local adaptation than foreign varieties.

Molecular characterization of CLPT1, a SEC4-like Rab/GTPase of the phytopathogenic fungus Colletotrichum lindemuthianum which is regulated by the carbon source

The gene CLPT1 (Colletotrichum lindemuthianum Protein Transport 1) encoding a Rab/GTPase was isolated from the filamentous fungus Colletotrichum lindemuthianum, the causal agent of bean anthracnose. At the amino acid level, CLPT1 shows between 54 and 80% identity to SEC4-like proteins, a class of molecules required for intracellular vesicular transport in yeasts. In particular, typical SEC4 domains involved in nucleotide binding and membrane attachment are present in the CLPT1 sequence. Functional identity of CLPT1 with SEC4 was confirmed by complementation of the Saccharomyces cerevisiae sec4-8 mutation. This is the first report of a gene involved in the control of intracellular vesicular trafficking in a phytopathogenic fungus. RNA blot analyses of CLPT1 expression were performed during in vitro growth of the fungus on synthetic media containing glucose or pectin, as single carbon source. The accumulation of CLPT1 mRNA was strongly increased on pectin, a plant cell wall polysaccharide that induces the production of extracellular pectinases, whereas the level of CLPT1 mRNA was below the detection threshold on glucose. These results suggest that CLPT1 is mainly involved in protein secretion and that the production of extracellular enzymes potentially involved in pathogenesis in filamentous fungi is sustained by induction of the genes involved in the secretory machinery.

Lp(a) is increased in hemodialysis patients according to the type of dialysis membrane: a 2-year follow-up study

AIMS

Patients with chronic renal failure treated by hemodialysis develop lipoprotein abnormalities that may contribute to their increased risk ofatherosclerosis. This study shows lipid parameter follow-up procedure according to the type of dialysis membrane in an unselected population of 33 hemodialysis patients.

PATIENTS AND METHODS

The study included 33 patients with end-stage renal disease and 110 healthy blood bank donors of Tenon Hospital. Cholesterol and triglycerides were determined by enzymatic methods, apoA-I, apoB by immunoturbidimetry and Lp(a) by immunonephelemetry. Apo(a) phenotyping was performed by agarose gel electrophoresis followed by immunoblotting. Patients and controls subjects were estimated by Student's t- and chi2-tests.

RESULTS

Patients dialyzed with low-flux membranes had Lp(a) concentrations higher than patients dialyzed with high-flux membranes. Patients dialyzed with polyacrylonitrile membranes (AN 69) had an apoA-I concentration significantly lower than patients dialyzed with hemophane or polysulfone membranes. We also confirmed some of the lipid abnormalities and high Lp(a) concentrations in ESRD patients.

CONCLUSION

These results may contribute to a more rational choice of the dialysis membrane in hemodialysis patients.

[Preservation of erythrocytes of heterozygous SC sickle cell patients]

In order to evaluate the feasibility of the autologous transfusion in an alloimmunized sickle cell patient, changes in the hematologic and biochemical characteristics of erythrocytes stored for 42 days from two patients with sickle cell SC anemia were compared with control subjects' (Hb A) red blood cells. Erythrocytes were stored in Saline Adenosine Dextrose Mannitol at +4 degrees C. The cryopreservation storage was made and 51Cr red cell survival was measured in one patient. No significant difference in the hematologic and biochemical parameters of the SC red blood cells and the control subjects was observed during the storage at +4 degrees C. Red cell survivals determined in fresh cells, cells stored for 42 days at +4 degrees C and thawed cells from one patient demonstrate much shorter half-life values than those of normal red blood cells. Before application, our results need to be confirmed by the same protocol with another patient with sickle cell SC.

Human mucin gene MUC4: organization of its 5'-region and polymorphism of its central tandem repeat array

In a previous study we isolated a partial cDNA with a tandem repeat of 48 bp, which allowed us to map a novel human mucin gene named MUC4 to chromosome 3q29. Here we report the organization and sequence of the 5'-region and its junction with the tandem repeat array of MUC4. Analysis of three overlapping genomic clones allowed us to obtain a partial restriction map of MUC4 and to locate the complete 48 bp tandem repeat domain on a PstI/EcoRI genomic fragment that exhibits a very large variation in number of tandem repeats (7-19 kb). cDNA clonal extension allowed us to obtain the entire 5' coding region of MUC4. Exon 1 consists of a 5' untranslated region and an 82 bp fragment encoding the signal peptide. This latter shows a high degree of similarity to the signal peptide of another apomucin, ASGP-1. Exon 2 is extremely large and contains a unique sequence that is followed by the whole tandem repeat domain. It encodes only one cysteine residue, making MUC4 different from mucin genes belonging to the 11p15.5 family. Moreover, an intron downstream from the tandem repeat array consists mainly of a 15 bp tandem repeat that exhibits a polymorphism in having a variable number of tandem repeats.

Natural history of GBV-C/hepatitis G virus infection through the follow-up of GBV-C/hepatitis G virus-infected blood donors and recipients studied by RNA polymerase chain reaction and anti-E2 serology

The aims of this study were to determine the outcome and the natural history of GBV-C/hepatitis G virus (HGV) infection and to establish the frequency of acute or persistent infections in multiply-transfused individuals and blood donors. We used a GBV-C/HGV RNA polymerase chain reaction (PCR) and an assay evidencing antibodies to the envelop protein E2, which is considered a marker for virus clearance. Among 16 PCR-positive recipients, 11 were still positive for GBV-C/HGV RNA at the end of the study period; six of the 16 recipients were GBV-C/HGV infected during the study period and thus had a well-defined date of infection. The 16 patients were shown to carry GBV-C/HGV RNA over a mean period of 4.4 years, for a mean observational period (defined as the follow-up period since the first sample positive for GBV-C/HGV RNA) of 5.3 years. Within the limits of the study period, the patients with a well-defined date of infection were positive for GBV-C/HGV RNA during a mean period of 4.7 years. If defined by the presence of GBV-C/HGV RNA for at least 6 months, the persistent infection rate was 100% in this recipient cohort. Serum anti-E2 antibody was evidenced at least once in five (31.2%) recipients and, except in one case, became detectable after the loss of GBV-C/HGV RNA. Among the 11 blood donors, all were still positive for GBV-C/HGV RNA after a mean follow-up period of 7.7 months. The persistent infection rate was 100% in this donor cohort. Once acquired, the infection to GBV-C/HGV generally tends to persist in immunocompetent patients.

Cellular and subcellular localization along the digestive and pulmonary tracts of a rabbit intestinal mucin differing from MUC2 and containing a 150 kDa light chain

Two immunologically different rabbit intestinal mucins were separated by performing fractionated ammonium sulfate precipitation, dialysis against pH 5.5 buffer and filtration through a Sepharose CL 2B column. They each contain a light chain with apparent molecular masses of 150 and 140 kDa, respectively. These L-chains were purified after reduction and carboxymethylation of the disulfide bridges of the native mucins, and their first 22 amino acid sequence was determined. The sequence of the 140 kDa chain is 100% and 95% identical to the N-terminal sequence of the L-chains from human and rat MUC2, respectively and only 54% identical to the sequence of the 150 kDa chain. It can be concluded that the rabbit counterpart of MUC2 exists and that another rabbit intestinal mucin, named here M-6G2, contains an L-chain. As in the case of MUC2, the M-6G2 L-chain may have resulted from a limited proteolysis. This proteolysis seems to occur in a region which is conserved in both mucins, since the two chains both have approximately the same length and the same five-amino acid N-terminal sequence. The cellular expression of M-6G2 along the digestive and respiratory tracts differs from that of the other mucins known so far to be present in the human small intestine.

Pretranslational regulation of pyruvate dehydrogenase complex subunits in white adipose tissue during the suckling-weaning transition in the rat

Total pyruvate dehydrogenase complex activity is low in white adipose tissue during the suckling period and increases markedly at weaning on to a high-carbohydrate diet. This is concomitant with an increase in the E1 alpha, E1 beta and E2 subunit protein concentration and their respective mRNAs, suggesting a pretranslational control of this phenomenon. The most marked change is seen for the E1 alpha subunit (17-fold increase in protein concentration). The changes in pyruvate dehydrogenase complex activity and subunit abundance induced by weaning on to a high-carbohydrate diet are precluded if the animals are weaned on to a high-fat diet, suggesting that the nutritional and/or related hormonal changes rather than a developmental stage are responsible for the observed adipose-tissue pyruvate dehydrogenase complex pattern.

Expression and glycosylation of the filamentous brush border glycocalyx (FBBG) during rabbit enterocyte differentiation along the crypt-villus axis

The filamentous brush border glycocalyx forming the ‘enteric surface coat’ of the intestinal epithelium is composed in rabbits of a 400 kDa mucin-type glycoprotein, which was purified using the 3A4 monoclonal antibody. This monoclonal antibody recognizes a filamentous brush border glycocalyx-specific glycosidic structure containing an O-acetylated sialic acid, which is absent from all the other glycoproteins in the epithelium, with the exception of certain goblet cell mucins. Here we establish that only 50% of the rabbits tested synthesized this glycosidic structure. Upon immunolabeling surface epithelia and sections of jejunum from these rabbits, the carbohydrate epitope recognized by the 3A4 mAb was found to be present on the filamentous brush border glycocalyx of a variable number of enterocytes, which were patchily distributed over all the villi. This heterogeneous expression of 3A4 antigenicity, which was also observed in the crypts, suggests the existence of differences between the patterns of differentiation of enterocytes, which results in the expression of different pools of glycosyltransferases and/or acetyl transferases. In mature enterocytes, the 3A4 determinants were present only on the filamentous brush border glycocalyx, which is anchored solely to the membrane microdomain at the tip of brush border microvilli. However, expression of 3A4 antigenicity begins in the median third of crypts, in enterocytes with a short, thin brush border devoid of apical filamentous brush border glycocalyx. Here the 3A4 epitopes were present over the whole brush border membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of fatty-acid-synthase gene expression by glucose in primary culture of rat hepatocytes. Dependency upon glucokinase activity

Fatty acid synthase (FAS) expression is low in liver and adipose tissue of suckling rats and increases markedly after weaning on to a high-carbohydrate low-fat diet. It has been shown previously that glucose alone, via an increase in intracellular glucose-6-phosphate level, stimulated the accumulation of FAS mRNA in cultured white adipose tissue of suckling rats. The regulation of FAS expression by glucose and hormones (insulin, dexamethasone and triiodothyronine) was studied in cultured hepatocytes from suckling rats. In hepatocytes cultured for 48 h in the absence of hormones and glucose, FAS mRNA, as well as glucokinase mRNA, levels remained undetectable. Glucose alone was unable to stimulate FAS expression. The combination of hormones, in the absence of glucose, has a marginal effect on FAS mRNA levels. However, FAS mRNA levels were increased in the presence of both glucose and the combination of hormones. This demonstrated that the hormonal induction of FAS mRNA was dependent on the presence of glucose in the culture medium. We have then investigated if glucokinase expression could be a prerequisite for the stimulation of FAS expression in response to glucose. Hepatocytes were cultured for 48 h in the absence of glucose but in the presence of insulin, dexamethasone and triiodothyronine. In these conditions, glucokinase mRNA and activity were markedly increased but there was no accumulation of FAS mRNA. When these hepatocytes were then exposed to various levels of glucose, FAS mRNA rapidly accumulated. Glucose stimulation of FAS expression was observed only in hepatocytes which expressed glucokinase activity. The importance of glucokinase expression for the induction of FAS mRNA by glucose is supported by the striking correlation between glucose-6-phosphate concentrations and the levels of FAS mRNA. This study clearly demonstrates that: (a) glucose metabolism is directly involved in the regulation of FAS gene expression; (b) the effect of hormones is partly due to their capacity to induce in the hepatocytes the capacity for glucose phosphorylation.

The filamentous brush border glycocalyx, a mucin-like marker of enterocyte hyper-polarization

The probably sole constituent of the filamentous brush border glycocalyx, which has been defined on the basis of electron microscopic data as a set of filaments radiating from the tip of rabbit intestinal brush border microvilli, has been purified. It consists of a mucin-type glycoprotein that can be solubilized by either Triton extraction or papain treatment of the brush border membrane vesicles but is insensitive to phosphatidylinositol phospholipase C. The detergent- and papain-solubilized forms both have the same apparent molecular mass of 400 kDa (SDS/PAGE). This suggests that the filamentous brush border glycocalyx may be anchored to the membrane by a small hydrophobic peptidic tail. Ser, Thr, Pro and Ala amount to 65% of the protein core amino acid residues. The glycosidic moiety, which amounts to 73% of the molecular mass, has high O-acetylated sialic acid contents. A monoclonal antibody (3A4) raised against the purified material was produced which specifically recognized the 400-kDa band by immunoprecipitation and immunoblotting, and the filamentous brush border glycocalyx of villus enterocytes when jejunum sections were immunolabelled. The 3A4 determinant was identified with a filamentous brush border glycocalyx-specific carbohydrate structure containing an O-acetylated sialic acid. The fact that the labeled glycocalyx was anchored entirely in a membrane microdomain at the tip of the microvilli shows that mature enterocytes are hyper-polarized epithelial cells.

Excessive glucose production, rather than insulin resistance, accounts for hyperglycaemia in recent-onset streptozotocin-diabetic rats

Glucose production and utilization and activities of key enzymes involved in liver and muscle glucose metabolism were studied in post-absorptive streptozotocin-diabetic rats after 12 h of severe hyperglycaemia (17.5 +/- 0.5 mmol/l) and insulinopenia (5 +/- 1 microU/ml). Basal glucose production was increased: 36.6 +/- 3.0 mg.kg.min-1, vs 24.4 +/- 2.5 in controls (p < 0.05); liver glycogen concentration was decreased by 40% (p < 0.05); liver phosphoenolpyruvate carboxykinase and glucose-6-phosphatase activities were increased by 375 and 156%, respectively (p < 0.001 and < 0.01). During a euglycaemic clamp at a plasma insulin level of 200 microU/ml, glucose production was totally suppressed in controls, but persisted at 20% of basal in diabetic rats. In these rats, glucose production was suppressed at a plasma insulin level of 2500 microU/ml. Basal whole body glucose utilization rate, 2-deoxy-1-[3H]-D-glucose ([3H]-2DG) uptake by muscles and muscle glycogen concentrations were similar in both groups, as well as total and active forms of pyruvate dehydrogenase and glycogen synthase activities. During the euglycaemic clamp, the total body glucose utilization rates and [3H]-2DG uptake by muscles were similar in control and diabetic rats at a plasma insulin level of 200 microU/ml, but lower in diabetic rats at a plasma insulin level of 2500 microU/ml. We conclude 1) in recent-onset severely insulinopenic rats, an excessive glucose production via gluconeogenesis prevailed, mainly accounting for the concomitant hyperglycaemia. This excess glucose output cannot be attributed to liver insulin resistance: the gluconeogenic pathway is physiologically less sensitive than glycogenolysis to the inhibition by insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of acarbose on glucose homeostasis, lipogenesis and lipogenic enzyme gene expression in adipose tissue of weaned rats

Acarbose is a potent intestinal glucosidase inhibitor which could have an anti-obesity property by reducing postprandial plasma glucose and insulin levels, potentially responsible for high rates of lipid synthesis in adipose tissue. We have tested this hypothesis by studying rats during the weaning period, when the lipogenic capacity of the adipose tissue develops. Rats were treated from age 19 days onwards with acarbose (10 mg/100 g diet) and studied at age 30 days. Acarbose was efficient in reducing postprandial excursions of both blood glucose and plasma insulin. Acarbose-treated rats behave like rats continuously infused with glucose with no metabolic signs of carbohydrate deprivation since gluconeogenesis was not activated. There was no massive caecal fermentation of carbohydrate since volatile fatty acids did not significantly increase in the portal blood. One of the most striking features of the acarbose-treated rats was the reduction of adipose tissue weight due to a reduced adipocyte size. This was concomitant with a reduced lipogenic capacity from glucose in isolated adipocytes under insulin stimulation. The activity of fatty acid synthase and acetyl-CoA carboxylase was decreased concomitantly with a reduced expression of their specific mRNA. This study allows the conclusion that postprandial hyperinsulinaemia and hyperglycaemia have a major role in the control of expression of lipogenic enzymes and thus on adipose tissue lipogenic capacity.

Insulin receptor function is preserved in a physiological state of hypoinsulinemia and insulin resistance

The suckling period in the rat is characterized by a continuously low plasma insulin concentration and a physiological insulin resistance, particularly in the adipose tissue. This insulin resistance disappears after weaning on the high-carbohydrate adult diet. We have studied the number, structure, and function of adipose tissue insulin receptors during the suckling-weaning transition. The insulin receptor number determined either on intact adipocytes or after partial purification was higher during suckling (15 days), whereas the affinity was similar when compared with weaned rats (30 days). The molecular weight of the alpha- and beta-subunits were identical in both groups and, when analyzed in nonreducing conditions, the alpha 2 beta 2-form was the unique detectable form of the receptor. Neither the basal and insulin-stimulated autophosphorylation of the insulin receptor beta-subunit nor the tyrosine kinase activity toward a synthetic substrate was decreased during the suckling period. Thus, in the adipose tissue of the suckling rat, a marked insulin resistance is concomitant with a normal insulin receptor number and function.