Role of the LFA3-CD2 interaction in human specific B cell differentiation

We examined the role of the lymphocyte function-associated (LFA)3 molecule in human B cell response. A mAb to this molecule did not influence B cell proliferation induced by anti-mu antibody and IL. In contrast, the same mAb inhibited the specific T-dependent B cell response induced by a particulate Ag. In the same line, two anti-CD2 mAb (directed toward the T11-1 and T11-2 epitopes) inhibited this response, whether used alone or in association. These inhibitions took place at an early stage of the response, and anti-LFA3 and anti-CD2 mAb acted on B cells and T cells, respectively. In contrast, when T cell help was provided by exogenous IL-2, the B cell response was resistant to the inhibitory effect of anti-LFA3 mAb. Taken together, these results indicate that the LFA3-CD2 pair play a major role in the direct T-B interaction required for T cell help.     

Phytosociological characteristics of theRondeletio correifoliae-Andropogonetum multinervosi ass. nova (Sierra de la Siguanea,Isla de la Juventud,Cuba)

The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel.     

Inactivation of the nopaline synthase gene by double transformation: reactivation by segregation of the induced DNA

Tobacco plants were transformed with derivatives of a binary vector pMON505 and two kanamycin resistant lines that were nopaline positive were selected for second transformation. The plasmids used for the second transformation were derivatives of pMON850 which carries the nopaline synthase gene in addition to a gene for gentamicin resistance. Insertion of each transgene was confirmed by Southern hybridization. Surprisingly, we found that more than 50% of the doubly transformed tobacco plants were nopaline negative. Tobacco plants that were transformed only by the second vector exhibited nopaline accumulation. DNA methylation patterns at the HpaII site in the promoter region of the nopaline synthase gene did not correlate with the nopaline phenotype. In some plant lines, seedlings of the R1 generation which segregated out the second T-DNA insertion recovered the nop⁺ phenotype. These results indicate that nopaline accumulation was inhibited by the presence of the second T-DNA.Abbreviations T-DNA transferred DNA - NPTII neomycin phosphotransferase II - uidA -glucuronidase - Km kanamycin - Gm gentamicin - nop⁺ nopaline positive - nop^– nopaline negative - MS medium, Murashige-Skoog medium     

The distribution of coastal fish eDNA sequences in the Anthropocene

Aim

Coastal fishes have a fundamental role in marine ecosystem functioning and contributions to people, but face increasing threats due to climate change, habitat degradation and overexploitation. The extent to which human pressures are impacting coastal fish biodiversity in comparison with geographic and environmental factors at large spatial scale is still under scrutiny. Here, we took advantage of environmental DNA (eDNA) metabarcoding to investigate the relationship between fish biodiversity, including taxonomic and genetic components, and environmental but also socio-economic factors.

Location

Tropical, temperate and polar coastal areas.

Time period

Present day.

Major taxa studied

Marine fishes.

Methods

We analysed fish eDNA in 263 stations (samples) in 68 sites distributed across polar, temperate and tropical regions. We modelled the effect of environmental, geographic and socio-economic factors on α- and β-diversity. We then computed the partial effect of each factor on several fish biodiversity components using taxonomic molecular units (MOTU) and genetic sequences. We also investigated the relationship between fish genetic α- and β-diversity measured from our barcodes, and phylogenetic but also functional diversity.

Results

We show that fish eDNA MOTU and sequence α- and β-diversity have the strongest correlation with environmental factors on coastal ecosystems worldwide. However, our models also reveal a negative correlation between biodiversity and human dependence on marine ecosystems. In areas with high dependence, diversity of all fish, cryptobenthic fish and large fish MOTUs declined steeply. Finally, we show that a sequence diversity index, accounting for genetic distance between pairs of MOTUs, within and between communities, is a reliable proxy of phylogenetic and functional diversity.

Main conclusions

Together, our results demonstrate that short eDNA sequences can be used to assess climate and direct human impacts on marine biodiversity at large scale in the Anthropocene and can further be extended to investigate biodiversity in its phylogenetic and functional dimensions.     

Gamma/delta T cell receptor positive T cells in the inflammatory joint: lack of association with response to soluble antigens

In patients with inflammatory synovitis, the proliferative response by lymphocytes from synovial fluid to soluble mycobacterial antigens is enhanced relative to those from peripheral blood. Earlier studies suggested that gamma/delta T cell receptor positive (TCR+) T lymphocytes may significantly contribute to the mycobacterial-specific synovial fluid response. We therefore examined the relationship of the T cell proliferative response to Mycobacterium tuberculosis antigens and the presence of gamma/delta TCR+ T cells employing several monoclonal antibodies. No consistent increase of gamma/delta TCR+ T cells was noted in inflammatory synovial fluids or tissues. Nonetheless, lymphocytes from the majority of the synovial fluids proliferated vigorously in response to water-soluble M. tuberculosis antigens. There was no relationship between the percentage of gamma/delta TCR+ T lymphocytes and the intensity of the proliferative response. In contrast, stimulation with whole mycobacterial organisms was capable of enriching the gamma/delta TCR+ cell population obtained from the peripheral blood of tuberculosis skin test positive normal controls and from some inflammatory synovial fluids. These observations do not support a role for mycobacteria reactive gamma/delta TCR+ synovial T lymphocytes in response to soluble mycobacterial antigens or in the local pathogenesis of inflammatory synovitis.     

Beitrag zur Kenntnis der chemischen Zusammensetzung derPhragmiti-Magnocaricetea und derAgropyro-Rumicion-Arten

Zwanzig Pflanzen der KlassePhragmiti-Magnocaricetea (Kennarten der einzelnen pflanzen-soziologischen Einheiten) und des VerbandesAgropyro-Rumicion crispi wurden den chemischen Analysen unterzogen. Die Pflanzenproben wurden auf den Wiesen der Trockengebiete S-Mährens und der SW-Slowakei gesammelt, u. zw. aus den pflanzensoziologisch, definierbaren Einheiten (Assoziationen der VerbändePhragmition, Caricion gracilis, Caricion rostratae undAgropyro-Rumicion). Die Resultate wurden mit der chemischen Zusammensetzung der in anderen Gebieten vorkommenden Pflanzen verglichen. Es zeigten sich Zusammenhänge zwischen der genetisch bedingten chemischen Zusammensetzung bestimmter Artengruppen und den Eigenschaften des Substrats. In diesem Sinne gibt es allgemeine Unterschiede zwischen den VerbändenCaricion gracilis undCaricion rostratae. Die Arten desAgropyro-Rumicion zeigen im Durchschnitt engere Bindung an die Gesellschaften desCnidion-Verbandes als an dasCaricion gracilis.