Interfering polysialyltransferase ST8SiaII/STX mRNA inhibits neurite growth during early hippocampal development

AbstractPolysialic acid (PSA) attached to NCAM is involved in cell–cell interactions participating in structural and functional plasticity of neuronal circuits. Two polysialyltransferases, ST8SiaII/STX and ST8SiaIV/PST, polysialylate NCAM. We previously suggested that ST8SiaII/STX is the key enzyme for polysialylation in hippocampus. Here, polysialyltransferase mRNA interference experiments showed that, knock down of ST8SiaIV/PST transcripts did not affect PSA expression, but PSA was almost absent from neuronal surfaces when ST8SiaII/STX mRNA was interfered. Non-polysialylated neurons bore a similar number of neurites per cell than polysialylated neurons. However, non-polysialylated processes were shorter and a lower density of synaptophysin clusters accompanied this reduced neuritic growth. Therefore, ST8SiaII/STX expression is essential to allow a correct neuritic development at initial stages of hippocampus ontogeny

The expression of the major shed Trypanosoma cruzi antigen results from the developmentally-regulated transcription of a small gene family

AbstractTo better understand the mechanisms involved in the developmental expression of Trypanosoma cruzi antigens we examined the gene structure and transcription properties of the major shed trypomastigote (SAPA). We report in this paper that SAPA is encoded by a small family of at least 6 genes which differ mainly in the length of a repeat region made up of tandemly arranged 36-bp repeat units. SAPA genes are located distant from chromosomal telomeres as inferred from their insensitivity to Ba131 nuclease treatment. Furthermore, Northern blot and S1 protection analyses strongly support the fact that most (or all) SAPA genes are transcribed in the infective form of the parasite

A Trypanosoma cruzi Small Surface Molecule Provides the First Immunological Evidence that Chagas' Disease Is Due to a Single Parasite Lineage

Chagas' disease is a major health and economic problem caused by the protozoan Trypanosoma cruzi. Multiple independently evolving clones define a complex parasite population that can be arranged into two broad genetic lineages termed T. cruzi I and II. These lineages have different evolutionary origin and display distinct ecological and biological traits. Here we describe a novel molecule termed TSSA for trypomastigote small surface antigen that provides the first immunological marker allowing discrimination between lineages. TSSA is a surface, glycosylphosphatidyl inositol (GPI)-anchored mucin-like protein, highly antigenic during the infection. TSSA sequences from different parasite isolates reveal a population dimorphism that perfectly matches with the two T. cruzi lineages. Interestingly, this dimorphism is restricted to the central region of the molecule, which comprises the immunodominant B cell epitopes. This sequence variability has a major impact on TSSA antigenicity, leading to no immunological cross-reactivity between both isoforms for antibodies present either in immunization or infection sera. Furthermore, the absolute seroprevalence for TSSA in confirmed Chagasic patients is restricted to T. cruzi II isoform, strongly suggesting that human infections are due to this particular subgroup. Even though association of T. cruzi II with Chagas' disease has been proposed based on molecular markers, this is the first immunological evidence supporting this hypothesis. The implications of these results for the future research on Chagas' disease could be envisaged

Gene discovery through genomic sequencing of Brucella abortus.

Brucella abortus is the etiological agent of brucellosis, a disease that affects bovines and human. We generated DNA random sequences from the genome of B. abortus strain 2308 in order to characterize molecular targets that might be useful for developing immunological or chemotherapeutic strategies against this pathogen. The partial sequencing of 1,899 clones allowed the identification of 1,199 genomic sequence surveys (GSSs) with high homology (BLAST expect value < 10(-5)) to sequences deposited in the GenBank databases. Among them, 925 represent putative novel genes for the Brucella genus. Out of 925 nonredundant GSSs, 470 were classified in 15 categories based on cellular function. Seven hundred GSSs showed no significant database matches and remain available for further studies in order to identify their function. A high number of GSSs with homology to Agrobacterium tumefaciens and Rhizobium meliloti proteins were observed, thus confirming their close phylogenetic relationship. Among them, several GSSs showed high similarity with genes related to nodule nitrogen fixation, synthesis of nod factors, nodulation protein symbiotic plasmid, and nodule bacteroid differentiation. We have also identified several B. abortus homologs of virulence and pathogenesis genes from other pathogens, including a homolog to both the Shda gene from Salmonella enterica serovar Typhimurium and the AidA-1 gene from Escherichia coli. Other GSSs displayed significant homologies to genes encoding components of the type III and type IV secretion machineries, suggesting that Brucella might also have an active type III secretion machinery.Instituto de Biotecnologia y Biologia Molecula

Clonado de genes de trypanosoma cruzi en vectores de expresión y purificación

Genes del Trypanosoma cruzi, parásito causante de la enfermedad de Chagas, fueron clonados en vectores pGEX. La expresión se hizo en Escherichia coli, induciendo las proteínas de fusión con IPTG y purificándolas por cromatografía de afinidad con glutation agarosa. Estas proteínas fueron analizadas por electroforesis y cuantificadas por el micrométodo de Bradfor

Clonado de genes de trypanosoma cruzi en vectores de expresión y purificación

Genes del Trypanosoma cruzi, parásito causante de la enfermedad de Chagas, fueron clonados en vectores pGEX. La expresión se hizo en Escherichia coli, induciendo las proteínas de fusión con IPTG y purificándolas por cromatografía de afinidad con glutation agarosa. Estas proteínas fueron analizadas por electroforesis y cuantificadas por el micrométodo de Bradfor

Trypanosoma cruzi isolates from Argentina and Chile grouped with the aid of DNA probes

Fifty-two isolates and several clones from Trypanosoma cruzi, the agent of Chagas' disease, were analyzed using cloned minicircles or total kinetoplast DNA as probes. Isolates were obtained from triatomines, guinea pigs and infected humans in the Central and Northern regions of Argentina and the North of Chile. 35% of all the randomly selected isolates could be identified with one cloned minicircle probe. This widely distributed T. cruzi group was detected on both sides of the Andes mountain range (Argentina and Chile) in Triatoma infestans as well as in human infections. Most of the other isolates could be grouped with four kinetoplast DNAs as probes, but their geographical distribution seems to be restricted as compared with the one mentioned above. These results confirm the heterogeneity of T. cruzi subspecies in nature and the usefulness of DNA probes to group them. © 1987