Biology subjects

Laurent, N.

Publications and source records attributed to Laurent, N..

7 recordsLinked to original sources

bioRxiv2025

Long-term population monitoring reveals an alarming decline in the endangered endemic Reunion Harrier Circus maillardi

Insular species are disproportionately vulnerable to extinction due to small population sizes, geographic isolation, and high susceptibility to stochastic and anthropogenic pressures. The endemic Reunion Harrier (Circus maillardi), the last breeding raptor on La Reunion (Indian Ocean), is currently listed as "endangered" (EN) on the IUCN Red List. Concerns have recently emerged regarding the demographic impacts of secondary poisoning from anticoagulant rodenticides used for rat control in agricultural landscapes, in addition to other threats such as habitat loss and fragmentation, and reduced genetic diversity. Here, we analysed data from three standardized island-wide breeding censuses (1998-2000, 2009-2010, 2017-2019), encompassing 355 sampling points and totalising > 1,500 h of observations, to quantify overall population trends and spatial variation within those. Using generalized additive mixed models accounting for spatial variation in the different census designs, we estimated a significant decrease of -46% (95% CI: -61% to -28%) in the relative abundance of breeding pairs at the island scale over 21 years (equivalent to three generations), which supports its current endangered (EN) status. Decline was more pronounced in the eastern part of the island (-56%, 95% CI: -69% to -40%) compared to the western part (-29%, 95% CI: -52% to +0.3%). Combined with previous work on inbreeding and mutational load, exposure to anticoagulant rodenticides and ongoing threats (habitat changes), these results suggest this harrier population is undergoing an extinction vortex that requires immediate and targeted, spatially explicit, conservation actions. We also recommend that population size continues to be monitored and that knowledge of demographic parameters be improved to guide adaptive management for the species.

ecology↗

bioRxiv2025

Reassessing the diversity and distribution of African rope squirrels (Funisciurus Trouessart, 1880)

The diversity, taxonomy, distribution and ecology of sub-Saharan tree squirrels remain under-researched. This study aims to elucidate the diversity and distribution of rope squirrels, genus Funisciurus Trouessart 1880, in the Congo Basin. We assembled the most comprehensive genetic and morphometric data set to date, on a significant portion of the geographical and taxonomic range of these squirrels (470 specimens from seven provinces of the Democratic Republic of Congo). We identified six main taxa: a previously undescribed Funisciurus species (here, Fx), three allopatric taxa of Funisciurus anerythrus (Fc, FaRB and FaLB), and two sympatric genetically distinct taxa (FbLB1, FbLB2), potentially belonging to a Funisciurus bayonii species complex. We then mapped their distribution, showing that the Congo and Kasai Rivers represent significant biogeographical barriers limiting the distribution of Funisciurus species. In addition to providing a baseline for research on the impact of climate change and habitat degradation on the abundance and distribution of rope squirrels, our findings support research on the role of rope squirrel species in the transmission of pathogens of public health importance. Teaser textWe studied the diversity and distribution of rope squirrels, genus Funisciurus Trouessart 1880, in the Congo Basin. By gathering the most comprehensive genetic and morphometric data to date on a significant part of the geographical and taxonomic range of these squirrels (specimens from seven provinces of the Democratic Republic of Congo), we identified six main taxa: one previously undescribed species, three allopatric taxa, and two genetically distinct sympatric taxa. We then mapped their distribution, showing that the Congo and Kasai rivers represent significant biogeographical barriers limiting the distribution of Funisciurus species. These results support research into the role of rope squirrel species in the transmission of pathogens of public health importance. Image for the online table of contents: African rope squirrel Photo credit: Bushnell photo trap set by Pascal Baelo

zoology↗

bioRxiv2025

High genetic diversity of mpox virus (MPXV) in three different rodent species in the Democratic Republic of the Congo (DRC)

Altough zoonotic spillover events continue to drive human mpox outbreaks in the Democratic Republic of the Congo (DRC), the wildlife reservoir of mpox virus (MPXV) remains unkown. To address this gap, we screened samples from 2,701 wild mammals, mainly rodents (59.7%), bats (26.4%) and shrews (12.1%). Only six (0.2%) animals were Orthopoxvirus (OPV) PCR positive. Near full-length MPXV sequences were obtained from two squirrels (Funisciurus anerythrus and Paraxerus sp.) and one soft furred mouse (Praomys jacksoni). A novel Taterapox virus was identified in a shrew (Crocidura cf. denti). All newly identified MPXV strains belong to clade Ia, but they cluster into different groups or subgroups, despite being collected from geographically close locations, and all are closely related to human MPXV strainsfrom the same regions. Our study provides for the first time clear evidence that MPXV diversity is not restricted to a single rodent host species nor confined to a geographic area. Importantly, MPXV positive Paraxerus and Praomys specimens were sampled close to Kisangani, a city with more than one million inhabitants, highlighting that spillover events can als ooccur in or near major cities, with more favorable conditions for interhuman transmissions and potential emergence of new lineages.

microbiology↗

bioRxiv2024

A wide diversity of viruses detected in African mammals involved in the wild meat supply chain

The processes involved in acquiring, trading, preparing, and consuming wild meat pose significant risks for the emergence of zoonotic infectious diseases. Several major viral outbreaks have been directly linked to the wild meat supply chain, yet our knowledge of the virome in many mammals involved in this chain remains limited and disproportionately focused on certain mammalian taxa and pathogens. This report presents the findings of a metagenomic viral screening of 99 specimens belonging to 27 wild African mammal species and one domesticated species, all traded for their meat. The study focuses on tissue and swab samples collected from various regions in the Democratic Republic of the Congo and in Brussels, Belgium. A total of fifteen virus strains were detected, belonging to the families Arteriviridae, Retroviridae and Sedoreoviridae (primates), Picobirnaviridae (primates and rodents), Picornaviridae (rodents), Hepadnaviridae (hyrax), Orthoherpesviridae (artiodactylid and carnivore) and Spinareoviridae (carnivore). Several strains were detected in mammalian hosts for the first time, expanding their host range and genetic diversity. Of note is the presence of viruses genetically related to recognised zoonotic pathogens, i.e., human picobirnavirus (Orthopicobirnavirus hominis) (primates and rodents), simian foamy viruses (Simiispumavirus) (primates), and rotavirus A (Rotavirus alphagastroenteritidis) (primates). The presence of these viruses in primates is concerning as non-human primates are phylogenetically closely related to humans, which can facilitate interspecies viral transmission. These findings underscore the high diversity of mammalian viruses and the potential risk of human infection through cross-species transmission during the close interactions with wildlife in the wild meat supply chain.

genomics↗

bioRxiv2024

Assessing Ebola Virus Circulation in the Tshuapa Province (Democratic Republic of the Congo): A One Health Investigation of Wildlife and Human Interactions

The wildlife reservoir and spillover mechanisms of the Ebola virus remain elusive despite extensive research efforts in endemic areas. This study employed a One Health approach to examine the virus circulation in wildlife and the associated human exposure risks in the Tshuapa province of the Democratic Republic of the Congo. In 2021, we collected 1015 samples from 888 animals, predominantly small mammals, and 380 inhabitants of Inkanamongo village, the site of an Ebola virus disease outbreak in 2014. These samples were screened for evidence of current (RNA) or past (IgG antibodies) Ebola virus infections. We also conducted interviews with 167 individuals in the surrounding districts to assess their interactions with wildlife. While no Ebola virus RNA was detected in the wildlife samples, anti-orthoebolavirus IgG antibodies were found in 13 bats and 38 rodents. Among the human participants, 120 individuals had IgG antibodies against at least one orthoebolavirus antigen, with 12 showing seropositivity for two antigens of the same orthoebolavirus, despite not having a prior Ebola disease diagnosis. Furthermore, over 50% of respondents reported frequent visits to the forest to hunt a variety of wild animals, particularly ungulates and rodents, which could account for occasional viral spillovers. The absence of active Ebola virus circulation in wildlife may reflect seasonal patterns in reservoir ecology, like those observed in bats. Similarly, seasonal human activities, like hunting and foraging, may result in periodic exposure risks. These findings highlight the importance of continuous, multidisciplinary surveillance to monitor changes in seasonal spillover risks.

molecular biology↗

bioRxiv2021

First observation of Aedes albopictus in the Tshuapa province (Boende) of the Democratic Republic of the Congo

In May-June 2021, we detected Aedes albopictus adults near the central hospital in Boende, the capital city of the Tshuapa province of the Democratic Republic of the Congo (DRC). We identified the mosquitoes using morphological and molecular techniques (COI barcoding). This is the first report of this species in the DRC outside of Kinshasa and Kongo Central. Given the central location of Boende in the Congo Basin, our finding suggests that the vector might also have spread to other cities which are located upstream of the Congo River and its major tributaries. Because Aedes albopictus is an important vector for human arbovirus transmission, we highlight the need to investigate its distribution range and to update disease risk maps in Central Africa.

evolutionary biology↗

bioRxiv2021

TALPID3/KIAA0586 regulates multiple aspects of neuromuscular patterning during gastrointestinal development in animal models and human

TALPID3/KIAA0586 is an evolutionary conserved protein, which plays an essential role in protein trafficking. Its role during gastrointestinal (GI) and enteric nervous system (ENS) development has not been studied previously. Here, we analysed chicken, mouse and human embryonic GI tissues with TALPID3 mutations. The GI tract of TALPID3 chicken embryos was shortened and malformed. Histologically, the gut smooth muscle was mispatterned and enteric neural crest cells were scattered throughout the gut wall. Analysis of the Hedgehog pathway and gut extracellular matrix provided causative reasons for these defects. Interestingly, chicken intra-species grafting experiments and a conditional knockout mouse model showed that ENS formation did not require TALPID3, but was dependent on correct environmental cues. Surprisingly, the lack of TALPID3 in enteric neural crest cells (ENCC) affected smooth muscle and epithelial development in a non cell-autonomous manner. Analysis of human gut fetal tissues with a KIAA0586 mutation showed strikingly similar findings compared to the animal models demonstrating conservation of TALPID3 and its necessary role in human GI tract development and patterning

developmental biology↗