Comptes Rendus Biologies最新文献

Shoot apical meristems are populations of stem cells which initiate the aerial parts of higher plants. Work during the last decades has revealed a complex network of molecular regulators, which control both meristem maintenance and the production of different types of organs. The behavior of this network in time and space is defined by the local interactions between regulators and also involves hormonal regulation. In particular, auxin and cytokinin are intimately implicated in the coordination of gene expression patterns. To control growth patterns at the shoot meristem the individual components of the network influence directions and rates of cell growth. This requires interference with the mechanical properties of the cells. How this complex multiscale process, characterized by multiple feedbacks, is controlled remains largely an open question. Fortunately, genetics, live imaging, computational modelling and a number of other recently developed tools offer interesting albeit challenging perspectives.

The concept of translational research, which originated in the medical field in the 1980s, consists in improving the efficient transfer of research results obtained in a species (which can be considered as a model or pivot) to all the species for which these results are of interest for its improvement in Agriculture. In this context, comparative genomics is an important tool for translational research, effectively identifying genes controlling common functions between species. Editing and phenotyping tools must thus allow the functional validation of the gene conserved within the species for which the knowledge has been extrapolated, that is to say transferred, and the identification of the best alleles and associated genotypes for exploitation in current breeding programs.

Most extant land plants establish a mutually beneficial relationship with soil fungi called mycorrhizal symbiosis. From their partners, plants get access to mineral nutrient and water resources transported via a fungal network that acts like an extension of their root systems. Using genetic and molecular tools, we showed that distant plant species use similar molecular mechanisms during the symbiosis. This similarity suggests that those mechanisms were inherited from their last common ancestor, a lineage that emerged from an aquatic environment 450 million years ago. Thus, this plant fungal interaction could have helped the first land plants without structures adapted to soil exploration to survive and colonize this new environment.

This article summarizes recent advances in our knowledge of plankton biogeography obtained by genomic approaches and the impacts of global warming on it. Large-scale comparison of the genomic content of samples of different plankton size fractions revealed a partitioning of the oceans into genomic provinces and the impact of major oceanic currents on them. By defining ecological niches, these provinces are extrapolated to all oceans, with the exception of the Arctic Ocean. By the end of the 21st century, a major restructuring of these provinces is projected in response to a high emission greenhouse gas scenario over 50% of the surface of the studied oceans. Such a restructuring could lead to a decrease in export production by 4%. Finally, obtaining assembled sequences of a large number of plankton genomes defining this biogeography has allowed to better characterize the genomic content of the provinces and to identify the species structuring them. These genomes similarly enabled a better description of potential future changes of plankton communities under climate change.

Clathrin-dependent endocytosis is the major pathway for the entry of most surface receptors and their ligands. It is controlled by clathrin-coated structures that are endowed with the ability to cluster receptors and locally bend the plasma membrane, leading to the formation of receptor-containing vesicles budding into the cytoplasm. This canonical role of clathrin-coated structures has been repeatedly demonstrated to play a fundamental role in a wide range of aspects of cell physiology. However, it is now clearly established that the ability of clathrin-coated structures to bend the membrane can be disrupted. In addition to chemical or genetic alterations, many environmental conditions can physically prevent or slow membrane deformation and/or budding of clathrin-coated structures. The resulting frustrated endocytosis is not only a passive consequence but serves very specific and important cellular functions. Here we provide a historical perspective as well as a definition of frustrated endocytosis in the clathrin pathway before describing its causes and many functional consequences.

Huntington's disease is a rare inherited neurological disorder that generally manifests in mild-adulthood. The disease is characterized by the dysfunction and the degeneration of specific brain structures leading progressively to psychiatric, cognitive and motor disorders. The disease is caused by a mutation in the gene coding for huntingtin and, although it appears in adulthood, embryos carry the mutated gene from their development in utero. Studies based on mouse models and human stem cells have reported altered developmental mechanisms in disease conditions. However, does the mutation affect development in humans? Focusing on the early stages of brain development in human fetuses carrying the HD mutation, we have identified abnormalities in the development of the neocortex, the structure that ensure higher cerebral functions. Altogether, these studies suggests that developmental defects could contribute to the onset symptoms in adults, changing the perspective on disease and thus the health care of patients.

Vivax malaria is an infectious disease caused by Plasmodium vivax, a parasitic protozoan transmitted by female Anopheline mosquitoes. Historically, vivax malaria has often been regarded as a benign self-limiting infection due to the observation of low parasitemia in Duffy-positive patients in endemic transmission areas and the virtual absence of infections in Duffy-negative individuals in Sub Saharan Africa. However, the latest estimates show that the burden of the disease is not decreasing in many countries and cases of vivax infections in Duffy-negative individuals are increasingly reported throughout Africa. This raised questions about the accuracy of diagnostics and the evolution of interactions between humans and parasites. For a long time, our knowledge on P. vivax biology has been hampered due to the limited access to biological material and the lack of robust in vitro culture methods. Consequently, little is currently known about P. vivax blood stage invasion mechanisms. The introduction of omics technologies with novel and accessible techniques such as third generation sequencing and RNA sequencing at single cell level, two-dimensional electrophoresis, liquid chromatography, and mass spectrometry, has progressively improved our understanding of P. vivax genetics, transcripts, and proteins. This review aims to provide broad insights into P. vivax invasion mechanisms generated by genomics, transcriptomics, and proteomics and to illustrate the importance of integrated multi-omics studies.

Recent advances in neurobiology, paleontology, and paleogenetics allow us to associate changes in brain size and organization with three main "moments" of increased behavioral complexity and, more speculatively, language development. First, Australopiths display a significant increase in brain size relative to the great apes and an incipient extension of postnatal brain development. However, their cortical organization remains essentially similar to that of apes. Second, over the last 2 My, with two notable exceptions, brain size increases dramatically, partly in relation to changes in body size. Differential enlargements and reorganizations of cortical areas lay the foundation for the "language-ready" brain and cumulative culture of later Homo species. Third, in Homo sapiens, brain size remains fairly stable over the last 300,000 years but an important cerebral reorganization takes place. It affects the frontal and temporal lobes, the parietal areas and the cerebellum and resulted in a more globular shape of the brain. These changes are associated, among others, with an increased development of long-distance-horizontal-connections. A few regulatory genetic events took place in the course of this hominization process with, in particular, enhanced neuronal proliferation and global brain connectivity.

In this paper, we present some thoughts about the recent developments, made possible by technological advances and miniaturisation of connected visual prostheses, linked to the visual system, operating at different level of this one, on the retina as well as in the visual cortex. While these objects represent a great hope for people with impaired vision to recover partial vision, we show how this technology could also act on the functional vision of well sighted persons to improve or increase their visual performance. In addition to the impact on our cognitive and attentional mechanisms, such an operation when it originates outside the natural real visual field (e.g. cybernetics) raises a number of questions about the development and use of such implants or prostheses in the future.