Comptes Rendus Biologies最新文献

The neutral theory of biodiversity and biogeography has stimulated much research in community ecology. Here, exact results are used to apply neutral model predictions to large regional samples. Three complementary neutral models are presented: the Ewens canonical neutral model, a model of subdivided ecological communities, and a “diversity begets diversity” neutral model. For all three models, an exact sampling formula is provided, and a new R package neutr, is presented. This package is used to fit species abundances from regional inventories of tropical forest trees in the Amazon, tropical Africa and Southeast Asia. It is shown that the neutral models fit well empirical data for all but the few most abundant species (from 6 to 40 depending on the continent). When the parameter θ is taken as an index or regional diversity, the Amazonia and Southeast Asia emerge with similar regional diversities (θ = 654 for Amazonia, versus θ = 726 for Southeast Asia), with a less diverse tropical African tree flora (θ = 219). The model infers 10,141 tree species with at least 50 individuals in Amazonia, 3477 in tropical Africa and 9915 in Southeast Asia. The spatially subdivided neutral model provides clear evidence for a spatial substructure in all three regional floras. These results show how neutral models are useful to explore regional patterns of species abundance and to provide insights about regional species pools.

Cytokinetic abscission is the final step of cell division, resulting in two separate daughter cells. While abscission is typically complete across most cell types, germline cells, which produce sexual gametes, do not finish cytokinesis, maintaining connections between sister cells. These connections are essential for sharing cytoplasm as they differentiate into oocyte and sperm. First, we outline the molecular events of cytokinesis during both complete and delayed abscission, highlighting the role of the ESCRT-III proteins. We then focus on recent discoveries that reveal the molecular mechanisms blocking abscission in Drosophila germline cells. The enzyme Usp8 was identified as vital for ensuring incomplete cytokinesis through the regulation of ESCRT-III ubiquitination and localization. Finally, we explore how the processes of incomplete cytokinesis could hold evolutionary importance, suggesting additional studies into choanoflagellates to comprehend the origins of multicellularity.

Beyond species extinction, it is likely that global change modifies selection regimes in natural populations. Whereas the classical Darwinian paradigm considers evolution as a slow process, it is now accepted that populations can evolve rapidly, in a few dozen generations. Plant-pollinator relationship is a central relationship in terrestrial ecosystems and the current pollinator decline can potentially disrupt this relationship. In this paper, we explore the possibility that reproductive systems in plants evolve in the face of pollinator decline. Using the case of a recent resurrection ecology study in Viola arvensis, the field pansy, we show that the evolution of a self-fertilization syndrome, and thus the breakdown of the plant-pollinator interaction, is in progress. Beyond the species itself, the evolution of reproductive regimes in plants involves relationships between species (pollinators and higher trophic levels). Thus, this example illustrates that global change is likely to affect biodiversity at different scales: from populations (Darwinian evolution) to ecosystem functions (relationships between species). This study shows that evolutionary processes modify the functioning of ecological systems and, where applicable, the related ecosystem services.

The convergence of biotechnologies with other disciplines, including computer science and Artificial Intelligence (AI), may make it possible to carry out dangerous genetic manipulations on pathogenic germs, as the gain-of-function experiments exacerbating virulence, as those carried out on myxoviruses and coronaviruses. Moreover, it is now possible to chemically synthesise any microorganism from in silico sequences, including the most dangerous viruses (poxviruses, Ebola, etc.), whose sequences are accessible. It might even be possible to use AI to design new germs that could be used as biological weapons.

Recent advances in live imaging technologies have refined our understanding of protein synthesis in living cells. Among the various approaches to live imaging of translation, this perspective highlights the use of antibody-based nascent peptide detection, a method that enables visualization of single-molecule translation in vivo. We examine how these advances improve our understanding of biological processes, particularly in developing organisms. In addition, we discuss technological advances in this field and suggest further improvements. Finally, we review some examples of how this method could lead to future scientific breakthroughs in the study of translation and its regulation in whole organisms.

Roger Guillemin discovered and characterized the hypothalamic factors that control anterior pituitary functions. He consequently demonstrated that these brain peptides regulate a large number of major body activities through neuroendocrine mechanisms. This especially include growth, fertility and reproduction, endocrine gland functions and stress. These seminal works paved the way to major applications in many fields of physiology and medicine for diagnosis, pharmacology and therapy, far beyond the initial discovery and properties of these molecules, including in cancerology, immunology, inflammation, drug addiction and behavior.

A large body of literature highlights the importance of energy metabolism in the response of haematological malignancies to therapy. In this review, we are particularly interested in acute myeloid leukaemia, where mitochondrial metabolism plays a key role in response and resistance to treatment. We describe the new concept of mitohormesis in the response to therapy-induced stress and in the initiation of relapse in this disease.

Fertility is declining worldwide and many couples are turning towards assisted reproductive technologies (ART) to conceive babies. Organisms that propagate via sexual reproduction often come from the fusion between two gametes, an oocyte and a sperm, whose qualities seem to be decreasing in the human species. Interestingly, while the sperm mostly transmits its haploid genome, the oocyte transmits not only its haploid set of chromosomes but also its huge cytoplasm to its progeny. This is what can be defined as the maternal inheritance composed of chromosomes, organelles, lipids, metabolites, proteins and RNAs. To decipher the decline in oocyte quality, it is essential to explore the nature of the maternal inheritance, and therefore study the last stages of murine oogenesis, namely the end of oocyte growth followed by the two meiotic divisions. These divisions are extremely asymmetric in terms of the size of the daughter cells, allowing to preserve the maternal inheritance accumulated during oocyte growth within these huge cells to support early embryo development. Studies performed in Marie-Hélène Verlhac's lab have allowed to discover the unprecedented impact of original acto-myosin based mechanisms in the constitution as well as the preservation of this maternal inheritance and the consequences when these processes go awry.

In nature, plants defend themselves against pathogen attack by activating an arsenal of defense mechanisms. During the last decades, work mainly focused on the understanding of qualitative disease resistance mediated by a few genes conferring an almost complete resistance, while quantitative disease resistance (QDR) remains poorly understood despite the fact that it represents the predominant and more durable form of resistance in natural populations and crops. Here, we review our past and present work on the dissection of the complex mechanisms underlying QDR in Arabidopsis thaliana. The strategies, main steps and challenges of our studies related to one atypical QDR gene, RKS1 (Resistance related KinaSe 1), are presented. First, from genetic analyses by QTL (Quantitative Trait Locus) mapping and GWAs (Genome Wide Association studies), the identification, cloning and functional analysis of this gene have been used as a starting point for the exploration of the multiple and coordinated pathways acting together to mount the QDR response dependent on RKS1. Identification of RKS1 protein interactors and complexes was a first step, systems biology and reconstruction of protein networks were then used to decipher the molecular roadmap to the immune responses controlled by RKS1. Finally, exploration of the potential impact of key components of the RKS1-dependent gene network on leaf microbiota offers interesting and challenging perspectives to decipher how the plant immune systems interact with the microbial communities' systems.

History has remembered Joseph Banks as the explorer-botanist of the first voyage of James Cook. Yet, shortly after his return, he got elected president of the Royal Society and, for over 40 years, he then played in Great Britain an eminent role in reorganizing natural sciences and advocating an "economic botany". He actively intervened in acclimatization and varietal selection of plants and animals in Great Britain as in the future English colonies. Thus he built an intellectual environment which will promote the emergence of Charles Darwin's thoughts.