Cutin deficiency in the tomato fruit cuticle consistently affects resistance to microbial infection and biomechanical properties, but not transpirational water loss

Plant cuticles are broadly composed of two major components: polymeric cutin and a mixture of waxes, which infiltrate the cutin matrix and also accumulate on the surface, forming an epicuticular layer. Although cuticles are thought to play a number of important physiological roles, with the most important being to restrict water loss from aerial plant organs, the relative contributions of cutin and waxes to cuticle function are still not well understood. Tomato ( Solanum lycopersicum ) fruits provide an attractive experimental system to address this question as, unlike other model plants such as Arabidopsis, they have a relatively thick astomatous cuticle, providing a poreless uniform material that is easy to isolate and handle. We identified three tomato mutants, cutin deficient 1 ( cd1 ), cd2 and cd3 , the fruit cuticles of which have a dramatic (95–98%) reduction in cutin content and substantially altered, but distinctly different, architectures. This cutin deficiency resulted in an increase in cuticle surface stiffness, and in the proportions of both hydrophilic and multiply bonded polymeric constituents. Furthermore, our data suggested that there is no correlation between the amount of cutin and the permeability of the cuticle to water, but that cutin plays an important role in protecting tissues from microbial infection. The three cd mutations were mapped to different loci, and the cloning of CD2 revealed it to encode a homeodomain protein, which we propose acts as a key regulator of cutin biosynthesis in tomato fruit.     

Early stages of neural crest ontogeny: formation and regulation of cell delamination

Long standing research of the Neural Crest embodies the most fundamental questions of Developmental Biology. Understanding the mechanisms responsible for specification, delamination, migration and phenotypic differentiation of this highly diversifying group of progenitors has been a challenge for many researchers over the years and continues to attract newcomers into the field. Only a few leaps were more significant than the discovery and successful exploitation of the quail-chick model by Nicole Le Douarin and colleagues from the Institute of Embryology at Nogent-sur-Marne. The accurate fate mapping of the neural crest performed at virtually all axial levels was followed by the determination of its developmental potentialities as initially analysed at a population level and then followed by many other significant findings. Altogether, these results paved the way to innumerable questions which brought us from an organismic view to mechanistic approaches. Among them, elucidation of functions played by identified genes is now rapidly underway. Emerging results lead the way back to an integrated understanding of the nature of interactions between the developing neural crest and neighbouring structures. The Nogent Institute thus performed an authentic "tour de force" in bringing the Neural Crest to the forefront of Developmental Biology. The present review is dedicated to the pivotal contributions of Nicole Le Douarin and her collaborators and to unforgettable memories that one of the authors bears from the time spent in the Nogent Institute. We summarize here recent advances in our understanding of early stages of crest ontogeny that comprise specification of epithelial progenitors to a neural crest fate and the onset of neural crest migration. Particular emphasis is given to signaling by BMP and Wnt molecules, to the role of the cell cycle in generating cell movement and to possible interactions between both mechanisms.     

Fibrin mechanisms and functions in nervous system pathology

In brain physiology, cerebrovascular interactions regulate both, vascular functions, such as blood vessel branching and endothelial cell homeostasis, as well as neuronal functions, such as local synaptic activity and adult neurogenesis. In brain pathology, including stroke, HIV encephalitis, Alzheimer Disease, multiple sclerosis, bacterial meningitis, and glioblastomas, rupture of the vasculature allows the entry of blood proteins into the brain with subsequent edema formation and neuronal damage. Fibrin is a blood-derived protein that is not produced by cells of the nervous system, but accumulates only after disease associated with vasculature rupture. This review presents evidence from human disease and animal models that highlight the role of fibrin in nervous system pathology. Our review presents novel experimental data that extend the role of fibrin, from that of a blood-clotting protein in cerebrovascular pathologies, to a component of the perivascular extracellular matrix that regulates inflammatory and regenerative cellular responses in neurodegenerative diseases.     

A Systems Immunology Approach to the Host-Tumor Interaction: Large-Scale Patterns of Natural Autoantibodies Distinguish Healthy and Tumor-Bearing Mice

Traditionally, immunology has considered a meaningful antibody response to be marked by large amounts of high-affinity antibodies reactive with the specific inciting antigen; the detection of small amounts of low-affinity antibodies binding to seemingly unrelated antigens has been considered to be beneath the threshold of immunological meaning. A systems-biology approach to immunology, however, suggests that large-scale patterns in the antibody repertoire might also reflect the functional state of the immune system. To investigate such global patterns of antibodies, we have used an antigen-microarray device combined with informatic analysis. Here we asked whether antibody-repertoire patterns might reflect the state of an implanted tumor. We studied the serum antibodies of inbred C57BL/6 mice before and after implantation of syngeneic 3LL tumor cells of either metastatic or non-metastatic clones. We analyzed patterns of IgG and IgM autoantibodies binding to over 300 self-antigens arrayed on slides using support vector machines and genetic algorithm techniques. We now report that antibody patterns, but not single antibodies, were informative: 1) mice, even before tumor implantation, manifest both individual and common patterns of low-titer natural autoantibodies; 2) the patterns of these autoantibodies respond to the growth of the tumor cells, and can distinguish between metastatic and non-metastatic tumor clones; and 3) curative tumor resection induces dynamic changes in these low-titer autoantibody patterns. The informative patterns included autoantibodies binding to self-molecules not known to be tumor-associated antigens (including insulin, DNA, myosin, fibrinogen) as well as to known tumor-associated antigens (including p53, cytokeratin, carbonic anhydrases, tyrosinase). Thus, low-titer autoantibodies that are not the direct products of tumor-specific immunization can still generate an immune biomarker of the body-tumor interaction. System-wide profiling of autoantibody repertoires can be informative.     

Influence of Software Tool and Methodological Aspects of Total Metabolic Tumor Volume Calculation on Baseline [18F]FDG PET to Predict Survival in Hodgkin Lymphoma

Aim

To investigate the respective influence of software tool and total metabolic tumor volume (TMTV0) calculation method on prognostic stratification of baseline 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography ([18F]FDG-PET) in newly diagnosed Hodgkin lymphoma (HL).

Methods

59 patients with newly diagnosed HL were retrospectively included. [18F]FDG-PET was performed before any treatment. Four sets of TMTV0 were calculated with Beth Israel (BI) software: based on an absolute threshold selecting voxel with standardized uptake value (SUV) >2.5 (TMTV0_2.5), applying a per-lesion threshold of 41% of the SUV_max (TMTV0₄₁) and using a per-patient adapted threshold based on SUV_max of the liver (>125% and >140% of SUV_max of the liver background; TMTV0₁₂₅ and TMTV0₁₄₀). TMTV0₄₁ was also determined with commercial software for comparison of software tools. ROC curves were used to determine the optimal threshold for each TMTV0 to predict treatment failure.

Results

Median follow-up was 39 months. There was an excellent correlation between TMTV0₄₁ determined with BI and with the commercial software (r = 0.96, p<0.0001). The median TMTV0 value for TMTV0₄₁, TMTV0_2.5, TMTV0₁₂₅ and TMTV0₁₄₀ were respectively 160 (used as reference), 210 ([28;154] p = 0.005), 183 ([-4;114] p = 0.06) and 143ml ([-58;64] p = 0.9). The respective optimal TMTV0 threshold and area under curve (AUC) for prediction of progression free survival (PFS) were respectively: 313ml and 0.70, 432ml and 0.68, 450ml and 0.68, 330ml and 0.68. There was no significant difference between ROC curves. High TMTV0 value was predictive of poor PFS in all methodologies: 4-years PFS was 83% vs 42% (p = 0.006) for TMTV0_2.5, 83% vs 41% (p = 0.003) for TMTV0_41, 85% vs 40% (p<0.001) for TMTV0₁₂₅ and 83% vs 42% (p = 0.004) for TMTV0₁₄₀.

Conclusion

In newly diagnosed HL, baseline metabolic tumor volume values were significantly influenced by the choice of the method used for determination of volume. However, no significant differences were found in term of prognosis.     

Rabies Virus Hijacks and Accelerates the p75NTR Retrograde Axonal Transport Machinery

Rabies virus (RABV) is a neurotropic virus that depends on long distance axonal transport in order to reach the central nervous system (CNS). The strategy RABV uses to hijack the cellular transport machinery is still not clear. It is thought that RABV interacts with membrane receptors in order to internalize and exploit the endosomal trafficking pathway, yet this has never been demonstrated directly. The p75 Nerve Growth Factor (NGF) receptor (p75NTR) binds RABV Glycoprotein (RABV-G) with high affinity. However, as p75NTR is not essential for RABV infection, the specific role of this interaction remains in question. Here we used live cell imaging to track RABV entry at nerve terminals and studied its retrograde transport along the axon with and without the p75NTR receptor. First, we found that NGF, an endogenous p75NTR ligand, and RABV, are localized in corresponding domains along nerve tips. RABV and NGF were internalized at similar time frames, suggesting comparable entry machineries. Next, we demonstrated that RABV could internalize together with p75NTR. Characterizing RABV retrograde movement along the axon, we showed the virus is transported in acidic compartments, mostly with p75NTR. Interestingly, RABV is transported faster than NGF, suggesting that RABV not only hijacks the transport machinery but can also manipulate it. Co-transport of RABV and NGF identified two modes of transport, slow and fast, that may represent a differential control of the trafficking machinery by RABV. Finally, we determined that p75NTR-dependent transport of RABV is faster and more directed than p75NTR-independent RABV transport. This fast route to the neuronal cell body is characterized by both an increase in instantaneous velocities and fewer, shorter stops en route. Hence, RABV may employ p75NTR-dependent transport as a fast mechanism to facilitate movement to the CNS.     

Optimal temperature for malaria transmission is dramatically lower than previously predicted

The ecology of mosquito vectors and malaria parasites affect the incidence, seasonal transmission and geographical range of malaria. Most malaria models to date assume constant or linear responses of mosquito and parasite life‐history traits to temperature, predicting optimal transmission at 31 °C. These models are at odds with field observations of transmission dating back nearly a century. We build a model with more realistic ecological assumptions about the thermal physiology of insects. Our model, which includes empirically derived nonlinear thermal responses, predicts optimal malaria transmission at 25 °C (6 °C lower than previous models). Moreover, the model predicts that transmission decreases dramatically at temperatures > 28 °C, altering predictions about how climate change will affect malaria. A large data set on malaria transmission risk in Africa validates both the 25 °C optimum and the decline above 28 °C. Using these more accurate nonlinear thermal‐response models will aid in understanding the effects of current and future temperature regimes on disease transmission.     

Programmed cell death occurs asymmetrically during abscission in tomato

Abscission occurs specifically in the abscission zone (AZ) tissue as a natural stage of plant development. Previously, we observed delay of tomato (Solanum lycopersicum) leaf abscission when the LX ribonuclease (LX) was inhibited. The known association between LX expression and programmed cell death (PCD) suggested involvement of PCD in abscission. In this study, hallmarks of PCD were identified in the tomato leaf and flower AZs during the late stage of abscission. These included loss of cell viability, altered nuclear morphology, DNA fragmentation, elevated levels of reactive oxygen species and enzymatic activities, and expression of PCD-associated genes. Overexpression of antiapoptotic proteins resulted in retarded abscission, indicating PCD requirement. PCD, LX, and nuclease gene expression were visualized primarily in the AZ distal tissue, demonstrating an asymmetry between the two AZ sides. Asymmetric expression was observed for genes associated with cell wall hydrolysis, leading to AZ, or associated with ethylene biosynthesis, which induces abscission. These results suggest that different abscission-related processes occur asymmetrically between the AZ proximal and distal sides. Taken together, our findings identify PCD as a key mechanism that occurs asymmetrically during normal progression of abscission and suggest an important role for LX in this PCD process.