Isolation of a Human Anti-HIV gp41 Membrane Proximal Region Neutralizing Antibody by Antigen-Specific Single B Cell Sorting

Broadly neutralizing antibodies are not commonly produced in HIV-1 infected individuals nor by experimental HIV-1 vaccines. When these antibodies do occur, it is important to be able to isolate and characterize them to provide clues for vaccine design. CAP206 is a South African subtype C HIV-1-infected individual previously shown to have broadly neutralizing plasma antibodies targeting the envelope gp41 distal membrane proximal external region (MPER). We have now used a fluoresceinated peptide tetramer antigen with specific cell sorting to isolate a human neutralizing monoclonal antibody (mAb) against the HIV-1 envelope gp41 MPER. The isolated recombinant mAb, CAP206-CH12, utilized a portion of the distal MPER (HXB2 amino acid residues, 673–680) and neutralized a subset of HIV-1 pseudoviruses sensitive to CAP206 plasma antibodies. Interestingly, this mAb was polyreactive and used the same germ-line variable heavy (VH1-69) and variable kappa light chain (VK3-20) gene families as the prototype broadly neutralizing anti-MPER mAb, 4E10 (residues 672–680). These data indicate that there are multiple immunogenic targets in the C-terminus of the MPER of HIV-1 gp41 envelope and suggests that gp41 neutralizing epitopes may interact with a restricted set of naive B cells during HIV-1 infection

Functional Memory B Cells and Long-Lived Plasma Cells Are Generated after a Single Plasmodium chabaudi Infection in Mice

Antibodies have long been shown to play a critical role in naturally acquired immunity to malaria, but it has been suggested that Plasmodium-specific antibodies in humans may not be long lived. The cellular mechanisms underlying B cell and antibody responses are difficult to study in human infections; therefore, we have investigated the kinetics, duration and characteristics of the Plasmodium-specific memory B cell response in an infection of P. chabaudi in mice. Memory B cells and plasma cells specific for the C-terminal region of Merozoite Surface Protein 1 were detectable for more than eight months following primary infection. Furthermore, a classical memory response comprised predominantly of the T-cell dependent isotypes IgG2c, IgG2b and IgG1 was elicited upon rechallenge with the homologous parasite, confirming the generation of functional memory B cells. Using cyclophosphamide treatment to discriminate between long-lived and short-lived plasma cells, we demonstrated long-lived cells secreting Plasmodium-specific IgG in both bone marrow and in spleens of infected mice. The presence of these long-lived cells was independent of the presence of chronic infection, as removal of parasites with anti-malarial drugs had no impact on their numbers. Thus, in this model of malaria, both functional Plasmodium-specific memory B cells and long-lived plasma cells can be generated, suggesting that defects in generating these cell populations may not be the reason for generating short-lived antibody responses

Copper translocation and tolerance in seedlings of tree species grown in contaminated soil

ABSTRACTHigh concentrations of copper (Cu) may be toxic to plants, yet some species can be tolerant to soils contaminated by this metal. The study aimed to evaluate Cu translocation and tolerance in seedlings of ‘timbaúva’ (Enterolobium contortisiliquum (Vell.) Morong), ‘pata-de-vaca’ (Bauhinia forficata Link) and ‘amendoim-bravo’ (Pterogyne nitensTul) subjected to Cu-contaminated soil. The study was conducted in a greenhouse for 120 days, using as substrate a clayey Oxisol. The experiment was set in a completely randomized design, using a 3 x 6 factorial scheme, corresponding to three forest species (‘timbaúva’, ‘pata-de-vaca’ and ‘amendoim-bravo’) and six Cu doses in the soil (0, 60, 120, 180, 240 and 300 mg kg-1), with six replicates. The following variables were analysed: total dry matter, Cu content and its accumulation in roots and shoots, tolerance and translocation indices and the coefficient of impact of the contamination on the relative contents of Cu in roots and shoots. ‘Timbaúva’ showed lower reduction in total dry matter with the increase of Cu doses in the soil, proving to be able to decrease Cu translocation to the shoots and tolerate doses of up to 236 mg kg-1 of this metal in the soil. ‘Timbaúva’ seedlings are more tolerant to contamination of Cu in soil, compared with seedlings of ‘amendoim-bravo’ and ‘pata-de-vaca’

Acumulação e translocação de zinco em mudas de espécies do gênero Eucalyptus e Corymbia

RESUMOO acúmulo e a compartimentalização de zinco são distintos entre as espécies florestais. O objetivo do trabalho foi, portanto, avaliar a capacidade de acumulação e de translocação de zinco em mudas de Eucalyptus e Corymbia em solo contaminado com zinco. O experimento foi conduzido no período de outubro de 2011 a março de 2012, em casa de vegetação, em delineamento experimental inteiramente casualizado, com arranjo fatorial (4 x 8), com doze repetições. Foram utilizadas quatro espécies: Eucalyptus. grandis W. Hill ex Maid., Eucalyptus. salignaSmith, Eucalyptus. dunnii Maiden e Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson, e oito doses de zinco (0, 140, 280, 420, 560, 700, 840 e 980 mg kg-1 de solo). As mudas das espécies florestais mostraram comportamento diferenciado em relação às doses de zinco aplicadas no solo com redução na massa seca da parte aérea. O E. dunnii apresenta maior redução na altura de planta, volume radicular, área foliar e massa seca radicular em relação às demais espécies. O C. citriodora apresenta maior acumulação de zinco na parte aérea e índice de translocação e baixo coeficiente de impacto do teor relativo com as doses aplicadas no solo, indicando tolerância em solos contaminados

Growth, tolerance and zinc accumulation in Senna multijuga and Erythrina crista-galli seedlings

ABSTRACT Zinc (Zn) is a micronutrient that is reaching toxic levels in the soil, with the intensification of agricultural and industrial activities. The objective of this study was to evaluate the growth, accumulation and tolerance of Erythrina crista-galli and Senna multijuga seedlings in soil with addition of increasing Zn levels. The study was conducted in a greenhouse for 120 days, using a completely randomized design in a 2 x 6 factorial arrangement, corresponding to two tree species (S. multijuga and E. crista-galli) and six doses of zinc in the soil (0, 200, 400, 600, 800 and 1000 mg kg-1) with six replicates. E. crista-galli and S. multijuga seedlings decreased root and shoot dry weight with increasing Zn doses. E. crista-galli and S. multijuga have low Zn translocation index and are capable to phytostabilize Zn in the roots. E. crista-galli had greater tolerance to Zn compared with S. multijuga. The species have potential for Zn phytostabilization programs in contaminated soil