A strategy for multimodal canopy images registration

Registration of complex and self-similar images such as plant canopy images is a challenge in plant sciences. Yet, this is often a required step for multimodal imaging, where unaligned sensors yield unregistered image pairs. We propose a pipeline adapted to such constraints, applied to apple tree canopies. Specifically, we apply an intensity-based registration on downscaled and/or Gaussian blurred versions of the targeted images. This helps to eliminate spurious details, which smooths the optimization landscape and also helps to reduce differences between the modalities. Results show better registration than with standard feature-based or intensity-based methods

Simulations de données afin d'améliorer la segmentation automatique de la tavelure du pommier

National audienc

Unresponsiveness to lymphoid-mediated signals at the neonatal follicular dendritic cell precursor level contributes to delayed germinal center induction and limitations of neonatal antibody responses to T-dependent antigens

The factors limiting neonatal and infant IgG Ab responses to T-dependent Ags are only partly known. In this study, we assess how these B cell responses are influenced by the postnatal development of the spleen and lymph node microarchitecture. When BALB/c mice were immunized with alum-adsorbed tetanus toxoid at various stages of their immune development, a major functional maturation step for induction of serum IgG, Ab-secreting cells, and germinal center (GC) responses was identified between the second and the third week of life. This correlated with the development of the follicular dendritic cell (FDC) network, as mature FDC clusters only appeared at 2 wk of age. Adoptive transfer of neonatal splenocytes into adult SCID mice rapidly induced B cell follicles and FDC precursor differentiation into mature FDC, indicating effective recruitment and signaling capacity of neonatal B cells. In contrast, adoptive transfer of adult splenocytes into neonatal SCID mice induced primary B cell follicles without any differentiation of mature FDC and failed to correct limitations of tetanus toxoid-induced GC. Thus, unresponsiveness to lymphoid-mediated signals at the level of neonatal FDC precursors delays FDC maturation and GC induction, thus limiting primary Ab-secreting cell responses to T-dependent Ags in early postnatal life

Lack of H-2 restriction of the Plasmodium falciparum (NANP) sequence as multiple antigen peptide

The major surface antigen of malaria sporozoites, the circumsporozoite protein, contains a region of tandem amino acid repeats, which in the case of the human malaria parasite Plasmodium falciparum, consist of four amino acids Asn-Ala-Asn-Pro (NANP) repeated up to about 40 times. This repetitive sequence has been considered as the basis for the development of subunit vaccines against P. falciparum malaria. We and others had previously shown that synthetic and recombinant NANP peptides were immunogenic only in H-2b mice. In the present report we show that, when mice with different H-2 haplotypes are immunized with the repetitive NANP sequence incorporated in a synthetic branching multiple antigen peptide (MAP), all except one of the mouse strains tested mounted an anti-peptide antibody response. Such a response does not appear to be due to the peculiar assembly of the NANP sequence. In fact, MAP containing repetitive sequences from circumsporozoite proteins of other malaria parasites did not overcome the genetic restriction of the immune response to the linear peptides. These data show that in the case of the P. falciparum NANP repeats, their immunogenicity can be dramatically changed and increased when these peptides are assembled as MAP. This unexpected finding may be of interest in the design of synthetic candidate malaria vaccines

Lack of H-2 restriction of the Plasmodium falciparum (NANP) sequence as multiple antigen peptide

The major surface antigen of malaria sporozoites, the circumsporozoite protein, contains a region of tandem amino acid repeats, which in the case of the human malaria parasite Plasmodium falciparum, consist of four amino acids Asn-Ala-Asn-Pro (NANP) repeated up to about 40 times. This repetitive sequence has been considered as the basis for the development of subunit vaccines against P. falciparum malaria. We and others had previously shown that synthetic and recombinant NANP peptides were immunogenic only in H-2b mice. In the present report we show that, when mice with different H-2 haplotypes are immunized with the repetitive NANP sequence incorporated in a synthetic branching multiple antigen peptide (MAP), all except one of the mouse strains tested mounted an anti-peptide antibody response. Such a response does not appear to be due to the peculiar assembly of the NANP sequence. In fact, MAP containing repetitive sequences from circumsporozoite proteins of other malaria parasites did not overcome the genetic restriction of the immune response to the linear peptides. These data show that in the case of the P. falciparum NANP repeats, their immunogenicity can be dramatically changed and increased when these peptides are assembled as MAP. This unexpected finding may be of interest in the design of synthetic candidate malaria vaccines

Immune responses to defined epitopes of the circumsporozoite protein of the murine malaria parasite, Plasmodium yoelii

We have investigated the immunogenicity of defined sequences of the circumsporozoite (CS) protein of the murine malaria parasite, Plasmodium yoelii. A 21-ner synthetic peptide from the nonrepetitive region of the CS protein (position 59-79, referred to as Py1) induced T cell proliferative responses in H-2d and, to a lesser extent, in H-2b mice. Conversely, a synthetic peptide (referred to as Py4) consisting of four (QGPGAP) repeats of the P. yoelii CS protein, induced an antibody response only in H-2b mice. No antibody response was observed when the Py3 peptide, consisting of three (QGPGAP) repeats, was used as an immunogen. When cross-linked to the Py4 repetitive peptide, the Py1 sequence behaved as a T helper epitope allowing the production of anti-Py4 antibodies in H-2d mice. Several long-term T cell lines and clones specific for the nonrepetitive Py1 peptide were originated in vitro from both H-2d and H-2b mice. These lines and clones were CD4+ and proliferated in a major histocompatibility complex-restricted fashion. Furthermore, Py1-specific T cell lines and clones did not proliferate in the presence of synthetic peptides from an analogous region of another rodent malaria parasite, P. berghei, despite the high degree of homology existing in this sequence of the two CS proteins. Finally, supernatants from 7 out of 13 clones (from BALB/c mice) produced detectable amounts of interleukin 2 and interferon-gamma; whereas supernatants from the 4 clones from C57BL/6 and 2 from BALB/c mice contained detectable amounts of interleukin 5. These results show that functionally heterogenous CD4+ T cell populations, belonging to either TH1 or TH2 subset, are activated upon immunization of mice with the P. yoelii Py1 synthetic peptide. It is not yet known what differential role these CD4+ subsets play during the malaria infection or after immunization with different malaria T cell epitopes. This knowledge may have a particular impact in the design of effective subunit vaccines against malaria

Impact of the SG phase morphology on the performances and durability of hybrid polymer membranes for fuel cell applications

International audienceProton-Exchange Membrane Fuel Cells (PEMFC) has emerged as a promising emission-free energy conversion device. However, the ionomer membrane at the heart of the device fails to deliver durable performance (to be achieved: 8000h for transportation, 50000h for stationary) at high temperature (100-150°C vs 80°C for std. Nafion) and low relative humidity (30%RH). The aim of our work is to improve existing membranes (better chemical and thermomechanical stabilities, better conductivities) by Sol-Gel (SG) hybridization. SG precursors are selected to diffuse through commercial membranes and introduce stabilizing organo-functional groups offering either a sacrificial stabilization (consumed over time) or a redox stabilization (regenerable) by degrading oxidizing agents produced during Fuel Cell operation. As the morphology (size, interaction/dispersion, connectivity) and localization (polar/apolar regions) of the SG phase inside the host matrix are parameters expected to be crucial for properties (H+ conductivity, water uptake), durability (H2O2-accelerated aging tests to assess the effectiveness of the reactive SG phase) and performances (FC operation) of the hybrid membranes, we explored their morphology at all relevant length scales. In this purpose, we use a combination of direct space (AFM/SEM/TEM) and reciprocal space (contrast variation SANS/SAXS) techniques (dimensional scale covered: from a hundred to a few nanometers) with regard to the chemistry of the SG Precursors (SGPs) (stabilization group, number of hydrolysable functions), yielding a variety of morphology (mass fractal structure vs. dispersed spherical aggregates vs. interconnected ones). H2O2-accelerated aging tests and preliminary fuel cell tests show promising operability of the hybrid membranes and the potential of the SG phase to inhibit the chemical ageing of sPEEK. With this work, we are confident to reach a predictive approach of the key parameters governing the final properties