High diversity in mucin genes and mucin molecules in Trypanosoma cruzi

Mucins are highly O-glycosylated molecules which in mammalian cells accomplish essential functions, like cytoprotection and cell-cell interactions. In the protozoan parasite Trypanosoma cruzi, mucin-related glycoproteins have been shown to play a relevant role in the interaction with and invasion of host cells. We have previously reported a family of mucin- like genes in T. cruzi whose overall structure resembled that of mammalian mucin genes. We have now analyzed the relationship between these genes and mucin proteins. A monoclonal antibody specific for a mucin sugar epitope and a polyclonal serum directed to peptide epitopes in a MUC gene-encoded recombinant protein, detected identical bands in three out of seven strains of T. cruzi. Immunoprecipitation experiments confirmed these results. When expressed in eukaryotic cells, the MUC gene product is post-translationally modified, most likely, through extensive O-glycosylation. Gene sequencing showed that the central domains encoding the repeated sequences with the consensus T 8KP 2, varies in number from 1 to 10, and the number of Thr residues in each repeat could be 7, 8, or 10. A run of 16 to 18 Thr residues was present in some, but not all, MUC gene-derived sequences. Direct compositional analysis of mucin core proteins showed that Thr residues are much more frequent than Ser residues. The same fact occurs in MUC gene- derived protein sequences. Molecular mass determinations of the 35-kDa glycoproteins further extend the heterogeneity of the family to the natural mucin molecules. Difficulties in assigning each of the several MUC genes identified to a mucin product arise from the high diversity and partial sequence conservation of the members of this family.Fil:Di Noia, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Pollevick, G.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Sánchez, D.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Trypanosoma cruzi surface mucins with exposed variant epitopes

The protozoan parasite Trypanosoma cruzi, the agent of Chagas disease, has a large number of mucin molecules on its surface, whose expression is regulated during the life cycle. These mucins are the main acceptors of sialic acid, a monosaccharide that is required by the parasite to infect and survive in the mammalian host. A large mucin-like gene family named TcMUC containing about 500 members has been identified previously in T. cruzi. TcMUC can be divided into two subfamilies according to the presence or absence of tandem repeats in the central region of the genes. In this work, T. cruzi parasites were transfected with one tagged member of each subfamily. Only the product from the gene with repeats was highly O-glycosylated in vivo. The O-linked oligosaccharides consisted mainly of β-D-Galp(1→4)-GlcNAc and β-D-Galp(1→4)[β-D-Galp(1→6)]-D-GlcNAc. The same glycosyl moieties were found in endogenous mucins. The mature product was anchored by glycosylphosphatidylinositol to the plasma membrane and exposed to the medium. Sera from infected mice recognized the recombinant product of one repeats-containing gene thus showing that they are expressed during the infection. TcMUC genes encode a hypervariable region at the N terminus. We now show that the hypervariable region is indeed present in the exposed mature N termini of the mucins because sera from infected hosts recognized peptides having sequences from this region. The results are discussed in comparison with the mucins from the insect stages of the parasite (Di Noia, J. M., D'Orso, I., Sanchez, D. O., and Frasch, A. C. C. (2000) J. Biol. Chem. 275, 10218-10227) which do not have variable regions.Fil:Pollevick, G.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Di Noia, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Salto, M.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Leguizamón, M.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:De Lederkremer, R.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

High diversity in mucin genes and mucin molecules in Trypanosoma cruzi

Mucins are highly O-glycosylated molecules which in mammalian cells accomplish essential functions, like cytoprotection and cell-cell interactions. In the protozoan parasite Trypanosoma cruzi, mucin-related glycoproteins have been shown to play a relevant role in the interaction with and invasion of host cells. We have previously reported a family of mucin- like genes in T. cruzi whose overall structure resembled that of mammalian mucin genes. We have now analyzed the relationship between these genes and mucin proteins. A monoclonal antibody specific for a mucin sugar epitope and a polyclonal serum directed to peptide epitopes in a MUC gene-encoded recombinant protein, detected identical bands in three out of seven strains of T. cruzi. Immunoprecipitation experiments confirmed these results. When expressed in eukaryotic cells, the MUC gene product is post-translationally modified, most likely, through extensive O-glycosylation. Gene sequencing showed that the central domains encoding the repeated sequences with the consensus T 8KP 2, varies in number from 1 to 10, and the number of Thr residues in each repeat could be 7, 8, or 10. A run of 16 to 18 Thr residues was present in some, but not all, MUC gene-derived sequences. Direct compositional analysis of mucin core proteins showed that Thr residues are much more frequent than Ser residues. The same fact occurs in MUC gene- derived protein sequences. Molecular mass determinations of the 35-kDa glycoproteins further extend the heterogeneity of the family to the natural mucin molecules. Difficulties in assigning each of the several MUC genes identified to a mucin product arise from the high diversity and partial sequence conservation of the members of this family.Fil:Di Noia, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Pollevick, G.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Sánchez, D.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Trypanosoma cruzi surface mucins with exposed variant epitopes

The protozoan parasite Trypanosoma cruzi, the agent of Chagas disease, has a large number of mucin molecules on its surface, whose expression is regulated during the life cycle. These mucins are the main acceptors of sialic acid, a monosaccharide that is required by the parasite to infect and survive in the mammalian host. A large mucin-like gene family named TcMUC containing about 500 members has been identified previously in T. cruzi. TcMUC can be divided into two subfamilies according to the presence or absence of tandem repeats in the central region of the genes. In this work, T. cruzi parasites were transfected with one tagged member of each subfamily. Only the product from the gene with repeats was highly O-glycosylated in vivo. The O-linked oligosaccharides consisted mainly of β-D-Galp(1→4)-GlcNAc and β-D-Galp(1→4)[β-D-Galp(1→6)]-D-GlcNAc. The same glycosyl moieties were found in endogenous mucins. The mature product was anchored by glycosylphosphatidylinositol to the plasma membrane and exposed to the medium. Sera from infected mice recognized the recombinant product of one repeats-containing gene thus showing that they are expressed during the infection. TcMUC genes encode a hypervariable region at the N terminus. We now show that the hypervariable region is indeed present in the exposed mature N termini of the mucins because sera from infected hosts recognized peptides having sequences from this region. The results are discussed in comparison with the mucins from the insect stages of the parasite (Di Noia, J. M., D'Orso, I., Sanchez, D. O., and Frasch, A. C. C. (2000) J. Biol. Chem. 275, 10218-10227) which do not have variable regions.Fil:Pollevick, G.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Di Noia, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Salto, M.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Leguizamón, M.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:De Lederkremer, R.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Use of neural networks in ground-based aerosol retrievals from multi-angle spectropolarimetric observations

In this paper, the use of a neural network algorithm for the retrieval of the aerosol properties from ground-based spectropolarimetric measurements is discussed. The neural network is able to retrieve the aerosol properties with an accuracy that is almost comparable to that of an iterative retrieval. By using the outcome of the neural network as first guess in the iterative retrieval scheme, the accuracy of the retrieved fine- and coarse-mode optical thickness is further improved, while for the other parameters the improvement is small or absent. The resulting scheme (neural network + iterative retrieval) is compared to the original one (look-up table + iterative retrieval) on a set of simulated ground-based measurements, and on a small set of real observations carried out by an accurate ground-based spectropolarimeter. The results show that the use of a neural-network-based first guess leads to an increase in the number of converging retrievals, and possibly to more accurate estimates of the aerosol effective radius and complex refractive index

AID overexpression leads to aggressive murine CLL and nonimmunoglobulin mutations that mirror human neoplasms

Immunobiology of allogeneic stem cell transplantation and immunotherapy of hematological disease

Mapping atmospheric aerosols with a citizen science network of smartphone spectropolarimeters

To assess the impact of atmospheric aerosols on health, climate, and air traffic, aerosol properties must be measured with fine spatial and temporal sampling. This can be achieved by actively involving citizens and the technology they own to form an atmospheric measurement network. We establish this new measurement strategy by developing and deploying iSPEX, a low-cost, mass-producible optical add-on for smartphones with a corresponding app. The aerosol optical thickness (AOT) maps derived from iSPEX spectropolarimetric measurements of the daytime cloud-free sky by thousands of citizen scientists throughout the Netherlands are in good agreement with the spatial AOT structure derived from satellite imagery and temporal AOT variations derived from ground-based precision photometry. These maps show structures at scales of kilometers that are typical for urban air pollution, indicating the potential of iSPEX to provide information about aerosol properties at locations and at times that are not covered by current monitoring efforts.Space EngineeringAerospace Engineerin