Tracking Agrobacterium strains by a RAPD system to identify single colonies from plant tumours

A molecular typing system for Agrobacterium strains based on the polymerase chain reaction–random amplified polymorphic DNA (PCR–RAPD) procedure was developed. It employs one to four different 10-mer primers and the results are highly reproducible. The band patterns obtained with the four primers for each of the 39 Agrobacterium strains analysed were different enough to differentiate the strains from each other. Strains with similar chromosomal background but different plasmid content, e.g. strains C58 and A281, gave the same band pattern with all the primers. Ten host plants were inoculated with eight Agrobacterium strains and the isolates obtained from the resulting tumours were analysed using the RAPD system developed here. The procedure allowed rapid identification of isolates recovered from tumours by comparison of their band patterns with band patterns of strains used as inoculum. The procedure also discriminated the various strains analysed. Purified bacterial cell suspensions, used for RAPD analyses, produced the same results as purified DNA, and greatly simplified the procedure. This system can be applied for rapid screening of Agrobacterium-like colonies isolated from plant tumours for epidemiological and genetic diversity studies.     

Induction of aggregation in porcine lymphoid cells by antibodies to CD46

CD46 is a major transmembrane glycoprotein that belongs to the regulator of complement activation (RCA) family. Recently, mAbs to human CD46 were shown to suppress IL-12 production. Here, we describe that mAbs against different porcine CD46 epitopes induced a marked adhesion of normal lymphocytes. Addition of low amounts of antibody to freshly isolated lymphocytes or thymocytes resulted in the clustering of the cells. Cross-linking of CD46 molecules seems essential since Fab fragments failed to induce aggregation. This aggregation was dependent on active cell metabolism and on the presence of divalent cations and required a functional cytoskeleton. It was not inhibited by antibodies to CD18, CD29, CD2, CD11a and CD11b. Staurosporine, an inhibitor of protein kinases, partially blocked the aggregation. This finding is indicative of a role of protein kinases in the transduction of the signal generated by CD46 engagement.     

Molecular cloning and characterisation of a homologue of the alpha inhibitor of NF-kappaB in the griffon vulture (Gyps fulvus)

NF-kappaB has been found to play roles in many different compartments of the immune system during differentiation of immune cells and development of lymphoid organs and during immune activation. The activity of NF-kappaB is primarily regulated by a family of structurally related proteins known as the IkappaB proteins. Herein, we report the molecular cloning and characterisation of a griffon vulture (Gyps fulvus) orthologue of the alpha inhibitor of NF-kappaB (IkappaBalpha). The full-length cDNA consists of 1553 bp with an ORF encoding a 313 amino acids protein (GenBank accession number EU161944). The putative G. fulvus IkappaBalpha protein (Gf-IkappaBalpha) possesses the characteristic organization of the mammalian IkappaBalpha proteins. Gf-IkappaBalpha contains an N-terminal signalling receiver domain, a central ankyrin repeat domain, required for its interaction with NF-kappaB, and a putative PEST-like sequence in the C-terminus. Quantitative real-time RT-PCR (qRT-PCR) analysis indicated that Gf-IkappaBalpha mRNA levels were higher in vulture heart, lung, artery and PBMC cells than in small and large intenstine and kidney. The predicted amino acid sequence of Gf-IkappaBalpha was 73% identical to human IkappaBalpha, and 91% identical to chicken IkappaBalpha. These results confirm the existence of the NF-kappaB signalling pathway in vulture and suggest a similar functional interaction between IkappaBalpha and NF-kappaB. Based on the results and the homology to the vertebrate NF-kappaB cascade, these studies help to highlight a potentially important regulatory pathway for the study of the related functions in vulture immune system.     

Conservation and use of genetic resources of cacao (Theobroma cacao L.) by gene banks and nurseries in six Latin American countries

Genetic Resources and Crop Evolution - Cacao (Theobroma cacao L.) is among the most important cash crops in tropical countries. The existing cacao genetic diversity represents a key resource to...     

Pathogenic fungi of planthoppers associated with rice crops in Argentina

We conducted a survey of pathogenic fungi of planthoppers associated with rice crops in Los Hornos, Buenos Aires, Argentina, and a study of the seasonality and prevalence of these pathogens. Samples were taken in rice for two consecutive years. The plants sampled included rice Oryza sativa L. (Poaceae) and its surrounding weeds. The planthopper Oliarus dimidiatus Berg. (Hemiptera: Fulgoromorpha: Cixiidae) was the most abundant species associated with rice. Two species of entomophthoralean and one species of hypocrealean fungi infected and killed adults of O. dimidiatus in the rice agroecosystem. The fungi were identified as: Pandora sp. (Entomophthorales: Entomophthoraceae), Conidiobolus coronatus (Costantin) Batko (Entomophthorales: Ancylistaceae), and Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Clavicipitaceae). Pandora sp. was the most predominant pathogen collected. It was recorded from the middle of February to the middle of April 2005, and not found again until the end of March 2006. The report of Pandora sp., C. coronatus and B. bassiana represents the first records of these fungi as pathogens of hoppers associated with rice crops in Argentina.