High-frequency antigens of human erythrocyte membrane sialoglycoproteins. VI. Monoclonal antibodies reacting with the N-terminal domain of glycophorin C

The epitopes of seven mouse monoclonal antibodies which are related to the Gerbich blood group system were investigated. BRIC4, BRIC10, GERO and MR4-130 have been published earlier. The three others (APO1, APO2, APO3) were prepared by immunization with normal human erythrocytes and detected by screening with red blood cells that lack glycophorins C and D. Using immunoblotting and hemagglutination inhibition assays, the epitopes for all antibodies were found to be located on glycophorin C. Hemagglutination inhibition experiments with peptides and chemically modified glycophorins revealed that MR4-130, GERO, BRIC10 and APO2 are all directed against identical or rather similar epitopes comprising the N-terminal three or four residues of glycophorin C. Modification of the N-terminal methionine residue or release of sialic acid attached to oligosaccharide(s) at the third and/or fourth position(s) destroyed all these antigens. The epitope of APO3 was found to comprise glutamic acid17 and/or aspartic acid19 as well as the oligosaccharide attached to serine15. The antigens of BRIC4 and APO1 were found to be located within the residues 2-21 and to comprise sialic acid attached to O-glycosidically linked oligosaccharide(s). However, these epitopes could not be elucidated further. Radio-iodinated MR4-130 bound to 39,000 receptor sites per normal red blood cell. Binding of the labelled antibody was completely inhibited by unlabelled MR4-130, BRIC10, APO2 and GERO. APO1 caused partial inhibition suggesting that it is directed against an adjacent site. BRIC4, APO3 and anti-Ge3 did not inhibit the binding of labelled MR4-130 to any significant extent.     

Molecular biodiversity of cassava begomoviruses in Tanzania: evolution of cassava geminiviruses in Africa and evidence for East Africa being a center of diversity of cassava geminiviruses

Cassava is infected by numerous geminiviruses in Africa and India that cause devastating losses to poor farmers. We here describe the molecular diversity of seven representative cassava mosaic geminiviruses (CMGs) infecting cassava from multiple locations in Tanzania. We report for the first time the presence of two isolates in East Africa: (EACMCV-[TZ1] and EACMCV-[TZ7]) of the species East African cassava mosaic Cameroon virus, originally described in West Africa. The complete nucleotide sequence of EACMCV-[TZ1] DNA-A and DNA-B components shared a high overall sequence identity to EACMCV-[CM] components (92% and 84%). The EACMCV-[TZ1] and -[TZ7] genomic components have recombinations in the same genome regions reported in EACMCV-[CM], but they also have additional recombinations in both components. Evidence from sequence analysis suggests that the two strains have the same ancient origin and are not recent introductions. EACMCV-[TZ1] occurred widely in the southern part of the country. Four other CMG isolates were identified: two were close to the EACMV-Kenya strain (named EACMV-[KE/TZT] and EACMV-[KE/TZM] with 96% sequence identity); one isolate, TZ10, had 98% homology to EACMV-UG2Svr and was named EACMV-UG2 [TZ10]; and finally one isolate was 95% identical to EACMV-[TZ] and named EACMV-[TZ/YV]. One isolate of African cassava mosaic virus with 97% sequence identity with other isolates of ACMV was named ACMV-[TZ]. It represents the first ACMV isolate from Tanzania to be sequenced. The molecular variability of CMGs was also evaluated using partial B component nucleotide sequences of 13 EACMV isolates from Tanzania. Using the sequences of all CMGs currently available, we have shown the presence of a number of putative recombination fragments that are more prominent in all components of EACMV than in ACMV. This new knowledge about the molecular CMG diversity in East Africa, and in Tanzania in particular, has led us to hypothesize about the probable importance of this part of Africa as a source of diversity and evolutionary change both during the early stages of the relationship between CMGs and cassava and in more recent times. The existence of multiple CMG isolates with high DNA genome diversity in Tanzania and the molecular forces behind this diversity pose a threat to cassava production throughout the African continent.     

New Insight on the Relationship between LDL Composition,Associated Proteins,Oxidative Resistance and Preparation Procedure

Oxidized low density lipoprotein (LDL) plays an important role in atherogenesis. It is generally thought that LDL is mainly oxidized in the intima of vessel walls, surrounded by hydrophilic antioxidants and proteins such as albumin. The aim of this study was to investigate the possible interrelationships between oxidation resistance of LDL and its protein and lipid moieties. Proteins and to a lesser extent lipids, appeared to be the major determinants in the LDL Cu 2+ -oxidation resistance, which in turn depend on the ultracentrifugation (UC) procedure used. Comparing high speed/short time (HS/ST, 4 &#117 h), high speed/long time (HS/LT, 6-16 &#117 h) and low speed/long time (LS/LT, 24 &#117 h) conditions of UC, HS with the shortest time (4 &#117 h) led to prepare LDL (named LDL·HS-4 &#117 h) with higher total protein and triglyceride contents, unchanged total cholesterol, phospholipids and Vitamin E, and higher Cu 2+ -oxidation resistance. Among proteins, only albumin allows to explain changes. PAF acetyl hydrolase appeared to be unaffected, whereas its pro-oxidant role was established and found only in the absence of albumin. In contrast the pro-oxidant role of caeruloplasmin took place regardless of the albumin content of LDL. The antioxidant effect of albumin (the oxidation lag time was doubled for 20 &#117 mol/mol albumin per LDL) is assumed to be due to its capacity at decreasing LDL affinity for Cu 2+ . Interestingly, the LDL·HS-4 &#117 h albumin content mirrored the intrinsic characteristics of LDL in the plasma and was not affected by added free albumin. Moreover, it has been verified that in 121 healthy subjects albumin was the best resistance predictor of the Cu 2+ -oxidation of LDL·HS-4 &#117 h, with a multiple regression equation: lag time (min)=62.1+0.67(HSA/apoB)+0.02 (TG/apoB) &#109 0.01(TC/apoB); r =0.54, P <0.0001. Accounted for by lag time, the oxidation resistance did not correlate with &#102 -tocopherol and ubiquinol contents of LDL. The mean albumin content was about 10 &#117 mol/mol, and highly variable (0-58 &#117 mol/mol) with subjects. The LDL·HS-4 &#117 h may account for the status of LDL in its natural environment more adequately than LDL resulting from other conditions of UC.     

Adaptation of acidogenic sludge to increasing glycerol concentrations for biohydrogen production

Hydrogen is a promising alternative as an energetic carrier and its production by dark fermentation from wastewater has been recently proposed, with special attention to crude glycerol as potential substrate. In this study, two different feeding strategies were evaluated for replacing the glucose substrate by glycerol substrate: a one-step strategy (glucose was replaced abruptly by glycerol) and a step-by-step strategy (progressive decrease of glucose concentration and increase of glycerol concentration from 0 to 5 g L^?1), in a continuous stirred tank reactor (12 h of hydraulic retention time (HRT), pH 5.5, 35 °C). While the one-step strategy led to biomass washout and unsuccessful H₂ production, the step-by-step strategy was efficient for biomass adaptation, reaching acceptable hydrogen yields (0.4?±?0.1 mol_H2?mol^?1 _{glycerol consumed}) around 33 % of the theoretical yield independently of the glycerol concentration. Microbial community structure was investigated by single-strand conformation polymorphism (SSCP) and denaturing gradient gel electrophoresis (DGGE) fingerprinting techniques, targeting either the total community (16S ribosomal RNA (rRNA) gene) or the functional Clostridium population involved in H₂ production (hydA gene), as well as by 454 pyrosequencing of the total community. Multivariate analysis of fingerprinting and pyrosequencing results revealed the influence of the feeding strategy on the bacterial community structure and suggested the progressive structural adaptation of the community to increasing glycerol concentrations, through the emergence and selection of specific species, highly correlated to environmental parameters. Particularly, this work highlighted an interesting shift of dominant community members (putatively responsible of hydrogen production in the continuous stirred tank reactor (CSTR)) according to the gradient of glycerol proportion in the feed, from the family Veillonellaceae to the genera Prevotella and Clostridium sp., putatively responsible of hydrogen production in the CSTR.     

Delayed blockade of the kinin B1 receptor reduces renal inflammation and fibrosis in obstructive nephropathy

Renal fibrosis is the common histological feature of advanced glomerular and tubulointerstitial disease leading to end-stage renal disease (ESRD). However, specific antifibrotic therapies to slow down the evolution to ESRD are still absent. Because persistent inflammation is a key event in the development of fibrosis, we hypothesized that the proinflammatory kinin B1 receptor (B1R) could be such a new target. Here we show that, in the unilateral ureteral obstruction model of renal fibrosis, the B1R is overexpressed and that delayed treatment with an orally active nonpeptide B1R antagonist blocks macrophage infiltration, leading to a reversal of the level of renal fibrosis. In vivo bone marrow transplantation studies as well as in vitro studies on renal cells show that part of this antifibrotic mechanism of B1R blockade involves a direct effect on resident renal cells by inhibiting chemokine CCL2 and CCL7 expression. These findings suggest that blocking the B1R is a promising antifibrotic therapy.     

Whole genome sequencing of a natural recombinant Toxoplasma gondii strain reveals chromosome sorting and local allelic variants

Background  

Toxoplasma gondii is a zoonotic parasite of global importance. In common with many protozoan parasites it has the capacity for sexual recombination, but current evidence suggests this is rarely employed. The global population structure is dominated by a small number of clonal genotypes, which exhibit biallelic variation and limited intralineage divergence. Little is known of the genotypes present in Africa despite the importance of AIDS-associated toxoplasmosis.