Typologie d'actualités: Team Molecular, Structural and Chemical Biology

When a non-conserved protein domain becomes essential

Rho-dependent termination of transcription is a critical regulatory mechanism specific to bacteria. In a subset of species including most Actinobacteria and Bacteroidetes, the Rho factor contains a large, poorly conserved N-terminal insertion domain (NID) of cryptic function. Through the first characterization of an actinobacterial Rho factor containing a very large NID (~40% of total mass), we show that such a non-conserved protein domain can be essential for activity. Without NID, the Rho factor of Bacteroides fragilis (BfRho) indeed cannot induce transcription termination and displays a reduced affinity for RNA. Intriguingly, the presence of a NID in BfRho is not correlated to the lack of residues or motifs deemed essential in NID-less Rho factors from evolutionary distinct species. The NID requirement is probably linked to the coevolution of partner feature(s) such as lineage-specific RNA polymerase domains and/or low G+C content of the B. fragilis transcriptome. Our data thus highlight that ‘essential function’ does not always rhyme with ‘structural conservation’.

Simon I., Delaleau M., Schwartz A., Boudvillain M.
A Large Insertion Domain in the Rho Factor From a Low G + C, Gram-negative Bacterium is Critical for RNA Binding and Transcription Termination Activity
Journal of Molecular Biology (2021) 433 (15) 167060 - Doi : 10.1016/j.jmb.2021.167060




Biodiversity skepticism?

Biodiversity skepticism?

Based on analysis of time series of abundances of insect species in the United States, Crossley et al. reported in Nature Ecology & Evolution (August 2020) that there is no evidence of a global decline in insect abundance or diversity in the United States, this for both natural and anthropogenic sites. Their study described the apparent robustness of insect populations in the U.S. as reassuring, in contrast to recent studies reporting dramatic declines in their abundance around the world.

However, a multidisciplinary consortium including researchers from INRAE, the University of Rennes and CNRS identified major problems in the Crossley et al. paper concerning: 1) statistical analysis and 2) inconsistencies in data selection. The consortium demonstrates, in a commentary published in Nature Ecology & Evolution Desquilbet et al. , that these biases call into question the conclusions of Crossley et al.

This is the second time (see here) that a high-ranking publication downplaying insect declines has been subject to methodological criticisms. These studies raise the question of a "biodiversity-skepticism" within the scientific community. In order to implement an appropriate protection of biodiversity, public decision-makers need an informed diagnosis that is not clouded by biased studies which slow down decision-making.

Reference :
Desquilbet M, Cornillon PA, Gaume L & Bonmatin JM (2021)
Matters arising: Adequate statistical modelling and data selection are essential when analysing abundance and diversity trends
Nature Ecology & Evolution doi : https://www.nature.com/articles/s41559-021-01427-x

J.-M. Bonmatin co-author of an article in One Health (18 March 2021)

The “One Health” concept links environmental, animal (wild & livestock) and human health. It is increasingly being argued (e.g. Covid-19) and is now essential for the preservation of ecosystems and public health. Researchers from the universities of Leuven (BE), Sorbonne-CNRS-IRD-INRAE-UPEC (FR), CARI (BE), FNOSAD (FR) and the Centre for Molecular Biophysics (CNRS), have applied this concept to the case of biocides and veterinary products (including pesticides) that are used to treat livestock and that impact pollinators. These researchers have shown that these "multi-use substances" present (among other things) proven risks for bees and consequently need to be better assessed before being placed on the market. This work was initiated at the CBM in 2019: see here & here (Italian).

Reference :     Mahefarisoa KL, Simon Delso N, Zaninotto V, Colin ME & Bonmatin JM (2021) The Threat of Veterinary Medicinal Products and Biocides on Pollinators: A One Health Perspective, One Health, https://doi.org/10.1016/j.onehlt.2021.100237

 




J.-M. Bonmatin co-author of a letter in Science

This letter is written by members of “the Task Force on Systemic Pesticides” (www.tfsp.info) of which JM Bonmatin is vice-chair. It recalls the fundamental principles of integrated pest management in agriculture, defined by the Food and Agriculture Organization (FAO). Integrated Pest Management first and foremost promotes risk prevention, and allows pesticides to be used only as a last resort, i.e. not in the first instance as in the case of prophylactic treatment (e.g. seeds coated with pesticides). The authors are concerned about the consequences of the recent signing of a strategic collaboration letter between the FAO and CropLife International (BASF, Bayer Syngenta, Corteva...). In fact, the authors point out the differences in the interpretation of IPM by CropLife International.

Reference : Kris Wyckhuys, Francisco Sanchez-Bayo, Alexandre Aebi, Maarten Bijleveld van Lexmond, Jean-Marc Bonmatin, Dave Goulson and Edward Mitchell, (2021) Stay true to integrated pest management, Science, 371 (6525), 133. https://doi.org/10.1126/science.abf8072

Decline in insect populations

A group of multidisciplinary co-authors from INRAE, CNRS and several universities (FR, BE & UK) has just published a scientific article in Science (Desquilbet et al., 2020). In the form of a ‘Technical comment’, this article identifies numerous data errors and methodological biases in a meta-analysis published in Science in April 2020 (Van Klink et al., 2020). As a result, the conclusions of Van Klink et al. on a more nuanced decline in terrestrial insects and on an increase in aquatic insects are invalidated. Our new publication reflects less the contradictory aspects of the research, than the emergence and growth of a "biodiversity scepticism". This biodiversity scepticism* must be apprehended. It minimises the impact of humans on nature (e.g. agriculture and pesticides) and is reminiscent of the climate scepticism that has caused a great deal of time to be lost in climate decision-making. J.-M. Bonmatin and his co-authors call for greater rigour in the conduct of such meta-analyses which are at the basis for stakeholders' decisions on key global issues.

Reference: Desquilbet M., Gaume L., Grippa M., Céréghino R., Humbert J.F., Bonmatin J.M., Cornillon P.A., Maes D., Van Dyck H. & Goulson D. (2020) Comment on “Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances”, Science, 370 (6523)

*See: The Conversation 2019, Nature 2020, Le Monde 2020 & Libération 2020

It is in the press: Le Monde 18/01/2021, The Conversation 28/01/2021, Le Monde 30/01/2021, Le Monde 04/02/2021 & CNRS-INEE 08/02/2021

 




Neonicotinoids

A scientific article linking the contamination of soils by neonicotinoid pesticides and their presence in hair of people in the Philippines has just been published by Jean-Marc Bonmatin et al. (2020) in the journal Science of the Total Environment. This article is part of researches carried out on human health by the Task Force on Systemic Pesticides, which brings together more than sixty independent researchers (www.tfsp.info & Facebook TFSP). This article also sheds light on the exposure of populations, particularly in the context of the possible reintroduction of neonicotinoids for sugar beet in France.

This article is highlighted by the CNRS chemistry institute.