Immunological relationship of extra-cellular polysaccharide antigens produced by different mould species

Moulds are able to produce extracellular polysaccharide antigens which are heat-stable and almost genus specific. Of 44 different strains of Penicillium 41 (93%) and all 12 strains of Aspergillus tested produced detectable quantities of an immunologically related antigen. Additionally 10 of these 56 strains produced an antigen immunologically related to the antigen produced by the genera Mucor and Fusarium. Immunologically different, but genus-specific antigens were produced by each of the species belonging to the genus Geotrichum, Fusarium, Cladosporium, Mucor and Rhizopus. The antigens produced by Mucor and Rhizopus, however, were immunologically related.     

Plant species identity and diversity effects on different trophic levels of nematodes in the soil food web

Previous studies on biodiversity and soil food web composition have mentioned plant species identity, as well as plant species diversity as the main factors affecting the abundance and diversity of soil organisms. However, most studies have been carried out under limitations of time, space, or appropriate controls. In order to further examine the relation between plant species diversity and the soil food web, we conducted a three-year semi-field experiment in which eight plant species (4 forb and 4 grass species) were grown in monocultures and mixtures of two, four and eight plant species. In addition there were communities with 16 plant species. We analyzed the abundance and identity of the nematodes in soil and roots, including feeding groups from various trophic levels (primary and secondary consumers, carnivores, and omnivores) in the soil food web.
Plant species diversity and plant identity affected the diversity of nematodes. The effect of plant diversity was attributed to the complementarity in resource quality of the component plant species rather than to an increase in total resource quantity. The nematode diversity varied more between the different plant species than between different levels of plant species diversity, so that plant identity is more important than plant diversity. Nevertheless the nematode diversity in plant mixtures was higher than in any of the plant monocultures, due to the reduced dominance of the most abundant nematode taxa in the mixed plant communities. Plant species identity affected the abundances of the lower trophic consumer levels more than the higher trophic levels of nematodes. Plant species diversity and plant biomass did not affect nematode abundance. Our results, therefore, support the hypothesis that resource quality is more important than resource quantity for the diversity of soil food web components and that plant species identity is more important than plant diversity per se.     

Heterophile antibodies to the antigens of myocardial interstitial connective tissue and erythrocytes in animals of different species

Reactions of heterophilic antibodies with antigens of the interstitial connective tissue (ICT) of the myocardium of different animals were studied and compared. The reactions were identical on bovine, pig, sheep and rabbit myocardium. The heterophilic antigen of the ICT of bovine myocardium was also found on bovine, rabbit and rat red cells and was absent on sheep red blood cells. It is suggested that heterophilic antigen of the ICT of the bovine myocardium is a novel heterophilic antigen, the specificity of which is linked with D-galactose and which differs from antigens of other heterophilic systems.     

Polyclonal antisera production by immunization with mixed cell antigens of different rhizobial species

Somatic antigens of Bradyrhizobium japonicum, Rhizobium sp. (Cicer arietinum) and Rhizobium sp. (Leucaena leucocephala) were prepared as standard, single-species type from cultured cells. Equal numbers of the cells of these rhizobia were then combined to obtain a mixed-rhizobial-species antigen preparation. Rabbits were immunized either with the standard, single-species type or with the mixed-rhizobial-species antigen preparations. The antisera developed from the mixed antigen immunization contained antibodies for all three rhizobial species, detectable at agglutination titres of over 800. The mixed-rhizobial-species antisera were made species specific by cross-absorption. The cross-absorbed and the mixed-rhizobial-species antisera were generally similar in quality for strain identification by agglutination, fluorescent antibodies, immunoblot and ELISA. A 66% reduction in cost was estimated for the production of antisera by immunization with mixed-rhizobial-species antigen.H.J. Hoben and P. Somasegaran are with the NifTAL Center and MIRCEN, University of Hawaii, 1000 Holomua Road, Paia, Maui, HI 96779-9744, USA: N. Boonkerd is with the School of Agricultural Technology, Suranaree University of Technology, University Avenue, Nakorn Racharsima, Thailand. Y.D. Gaur is with the Division of Microbiology, Indian Agricultural Research Institute, New Delhi-110012, India.     

Characterization of the Precipitin Bands Detected in the Immunodiffusion Test for Paracoccidioidomycosis

In order to characterize the precipitin bands detected in the immunodiffusion test for paracoccidioidomycosis, a study was undertaken in 54 patients with the disease. On the basis of the pattern of known control sera, the three commonly observed lines of precipitate were designated as 1, 2, and 3 according to their location in the immunodiffusion plate. At time of diagnosis, 28 of the patients exhibited all three bands, 16 gave two bands, and 10 showed only one precipitin line. Over 50 of the sera with three bands had high complement fixation titers (above 1:512), whereas those with one band exhibited lower titers. A similar picture was obtained with the quantitative agar-gel techniques, where titers of 1:64 and above were more commonly observed in sera with three precipitin lines. Follow-up studies carried out in 18 patients revealed that band 3 disappeared first, followed by band 2, and, finally, by band 1. At the end of 2 to 3 years, 85.7% of the patients had lost band 3, 75% band 2, and only 27.7% band 1. Cross-reactions with histoplasmin were found in eight patients who gave the M precipitin line with this antigen. It was found that the latter band and our paracoccidioidin band 3 fused, producing lines of identity. Bands 1 and 2 were specific. The implications of these findings are discussed.     

Population studies of the HLA-linked SB antigens

Using allogeneic T-cell recognition we have previously defined five new histocompatibility antigens designated SB antigens. To standardize typing for these antigens, cryopreserved, primed lymphocytes are now used as standard reagents and a technique of cluster analysis has been modified to score typing results objectively. Two primed lymphocyte reagents are used to define each SB antigen; although derived from independent responder-stimulator combinations, the concordance between the reagents is good (r is greater than 0.86). The SB-antigen distribution in a population of 215 normal donors is consistent with Hardy-Weinberg equilibrium of alleles of a single locus. Estimated gene frequencies ranged between 3 percent (SB5) and 36 percent (SB4) with 31 percent blanks. Analysis of association between the SB antigens and A, B, DR antigens in 200 normal donors revealed that associations were generally weak with a few exceptions, in particular, the A1, B8, DR3, SB1 haplotype and also the B7, DR2, SB5 haplotype.Abbreviations MHC major histocompatibility complex - PLT primed lymphocyte typing - SB secondary B cell (antigen)     

Purification and properties of extracellular polysaccharide (EPS) antigens produced by different mould species

Extracellular polysaccharide (EPS) antigens produced by different mould species were purified and partially characterized. Purification included (NH4)2SO4 treatment, Sepharose CL-4B column chromatography and Con A-sepharose chromatography. The EPS of Penicillium digitatum, Mucor racemosus and Cladosporium cladosporioides showed high antigenic capacities. Immunologically the EPS were partially genus-specific, but cross-reactivity was observed. The EPS antigens produced by species of Penicillium, Aspergillus repens and Geotrichum candidum lost their immunological activity upon heating (100 degrees C) at pH 1.8, while the EPS antigen of M. racemosus, Rhizopus oligosporus and C. cladosporioides were stable under the same conditions. The dominant monosaccharides present in the EPS antigen were mannose, galactose and glucose. The EPS obtained from cultures of M. racemosus and R. oligosporus also contained rhamnose. In the EPS produced by Penicillium spp. and A. repens the galactose residues were determined to be immunodominant.     

Genetic identity affects performance of species in grasslands of different plant diversity: an experiment with Lolium perenne cultivars

Background and Aims

Recent biodiversity research has focused on ecosystem processes, but less is known about responses of populations of individual plant species to changing community diversity and implications of genetic variation within species. To address these issues, effects of plant community diversity on the performance of different cultivars of Lolium perenne were analysed.

Methods

Populations of 15 genetic cultivars of Lolium perenne were established in experimental grasslands varying in richness of species (from 1 to 60) and functional groups (from 1 to 4). Population sizes, mean size of individual plants, biomass of individual shoots and seed production were measured in the first and second growing season after establishment.

Key Results

Population sizes of all cultivars decreased with increasing community species richness. Plant individuals formed fewer shoots with a lower shoot mass in more species-rich plant communities. A large proportion of variation in plant size and relative population growth was attributable to effects of community species and functional group richness, but the inclusion of cultivar identity explained additional 4–7 % of variation. Cultivar identity explained most variation (28–51 %) at the shoot level (biomass of individual tillers and reproductive shoots, seed production, heading stage). Coefficients of variation of the measured variables across plant communities were larger in cultivars with a lower average performance, indicating that this variation was predominantly due to passive growth reductions and not a consequence of larger adaptive plastic responses. No single cultivar performed best in all communities.

Conclusions

The decreasing performance of Lolium perenne in plant communities of increasing species richness suggests a regulation of competitive interactions by species diversity. Genetic variation within species provides a base for larger phenotypic variation and may affect competitive ability. However, heterogeneous biotic environments (= plant communities of different species composition) are important for the maintenance of intra-specific genetic variation.Key words: Biodiversity, competition, genetic variation, growth reduction, Lolium perenne, phenotypic plasticity, species richness     

Monoclonal antibodies against defined Leishmania antigens protect mice against infection by different species of Leishmania

Mice monoclonal antibodies (IgG) have been raised against Leishmania infantum promastigotes by fusing SP 2/0 myeloma cells and immunized mice splenic cells. The monoclonal antibodies have been detected by indirect immunofluorescence. In vivo tests showed that some of them could inhibit the life cycle of several Leishmania species from the Old and the New World. Studies of these protective monoclonals by the western blot technique showed the presence of three constant antigens (40 kD, 70 kD and 113 kD) amongst the Leishmania species studied.     

Genomic fingerprinting: new possibilities in determining the species identity of Brucella

The genomes of various Brucella species were shown to contain hypervariable sequences which can be detected by the M13 DNA. It has been demonstrated that the method of DNA fingerprinting opens up new possibilities in differentiation and identification of Brucellosis agents.