Biology subjects

Diarra, A. Z.

Publications and source records attributed to Diarra, A. Z..

4 recordsLinked to original sources

bioRxiv2026

Optimized MALDI-TOF mass spectrometry enables reliable identification of freshwater snails from schistosomiasis-endemic areas in Mauritania

Freshwater snails act as intermediate hosts for parasites affecting both humans and livestock, including schistosomes. In Mauritania, however, the diversity, distribution, and infection status of these snails remain poorly documented. This study aimed to identify freshwater snail species collected from two schistosomiasis-endemic areas in southern Mauritania, characterize their spatial distribution, and assess their infection rates using molecular tools Malacological surveys were conducted in Kankossa and Oued Rawdha during the 2023 rainy season. A total of 806 snail specimens were collected and preserved in 70% ethanol at 4 {degrees}C prior to analysis. Five species were identified morphologically and confirmed by molecular analysis: Bulinus truncatus, B. forskalii, B. senegalensis, B. umbilicatus, and Melanoides tuberculata. MALDI-TOF MS generated high-quality spectra for 99.0% of specimens and correctly identified 99.9% of analyzable samples after molecular confirmation of discrepant cases. Preservation in ethanol at 4 {degrees}C markedly improved spectral quality compared with previously reported room-temperature storage conditions Distinct ecological distributions were observed according to water body type. B. senegalensis and B. umbilicatus were exclusively collected from temporary ponds, whereas B. truncatus, B. forskalii, and M. tuberculata were found in permanent water bodies. Real-time PCR screening detected Schistosoma haematobium complex DNA in 239/798 (29.9%) specimens, with substantially higher infestation rates in Kankossa than in Oued Rawdha. These findings demonstrate that MALDI-TOF MS is a rapid, accurate, and field-compatible tool for freshwater snail identification, including closely related species that are difficult to distinguish morphologically. This approach could facilitate large-scale epidemiological surveillance and improve monitoring of schistosomiasis transmission dynamics in endemic settings.

molecular biology↗

bioRxiv2025

Identification by MALDI-TOF MS of Coleopteran insect pests collected in the field

In the context of museum and cultural heritage protection, rapid and accurate identification of Coleopteran pests is crucial. This study evaluated the effectiveness of MALDI-TOF MS in identifying seven species of Coleoptera collected between 2014 and 2023 from 17 French cultural sites. A total of 273 specimens (205 field-collected and 68 laboratory-reared) were analysed. Although reproducible and species-specific MS spectra were obtained, intra-species reproducibility was higher for laboratory reared specimens frozenly-stored compared to counterparts field collected and stored at room temperature. Two successive blind tests were done against the reference MS database including, firstly (ie, database 1, DB1), only laboratory-reared Coleoptera MS spectra, and secondly, those of DB1 upgraded with MS spectra from field collected specimens (ie, BD2). Correct identification at the species were obtained for MS spectra query against DB1 for species which possess homolog in the database. However, the spectra reaching threshold for relevant identification were coming from essentially laboratory-reared Coleoptera. An upgrading of the reference MS database (ie, BD2), improved identification performance for field specimens, although limitations remained for species with MS spectra of low peak diversity like Pentarthrum huttoni. In parallel, three specimens per species and storing mode were submitted to molecular identification using COI and 16S markers. For field samples, the rate of successful PCR product sequencing was lower than 10%, which was likely attributed to DNA degradation of these samples stored long term at room temperature. Overall, the study confirmed that MALDI-TOF MS appeared as a promising tool for Coleopteran pest identification, especially when reference spectra matched both species and preservation mode.

zoology↗

bioRxiv2025

Morphological and MALDI-TOF MS identification of freshwater snails, including intermediate hosts of schistosomes in Gabon.

A thorough knowledge of intermediate snail hosts and their geographical distribution is essential to understanding the transmission of schistosomiasis and to inform interventions in Gabon. Accurate identification of both snails species and Schistosoma species is therefore essential. The aim of this study was to identify the intermediate hosts of Schistosoma spp. (snails) using MALDI-TOF MS. MethodsSnails were collected from various sites across Gabon and were morphologically identified to species or genus level. Snail species were randomly selected, dissected and subjected to MALDI-TOF MS and molecular analysis. Parasites were detected by cercarial emission, followed by qPCR analysis and sequencing. ResultsA total of 3,722 snails were collected and morphologically identified as Bulinus truncatus (n=1845), Bulinus forskalii (n=381), Gyraulus costulatus (n=680), Bellamya sp. (n=67) and Melania sp. (n=749). Of the 3,722 snails collected, 21.2% (n = 791) were selected for further analysis, including Bu. truncatus (n = 301), Bu. forskalii (n = 158), and Gy. costulatus (n=147). A subset of 65 snails was subjected to molecular identification to confirm morphological classification, using COI, ITS, and 18S gene. BLAST analysis of the resulting sequences showed 97-100% identity with reference sequences of Bu. truncatus, Bu. forskalii, and Gy. costulatus available in GenBank. Analysis of the MS spectra from the 791 snails revealed that 78.2% (n = 618) were of high quality, with signal intensities exceeding 3,000 arbitrary units (a.u.). The MALDI-TOF MS reference database was subsequently updated with 12 high-quality spectra, comprising four representative spectra for each snail species. A blind test of 606 remaining spectra against the database. A blind test of the remaining 606 spectra, using the updated MALDI-TOF MS reference database, demonstrated reliable identification of 100% (Bulinus forskalii, 147/147; Gyraulus costulatus, 158/158) and 96% (Bulinus truncatus, 289/301) of the specimens. These results were consistent with morphological identification, with log score values (LSVs) ranging from 1.7 to 2.8. Principal component analysis (PCA) showed that Bulinus species clustered according to their geographical origin. Overall, 17,66% of the snails analysed were found to be positive for Schistosoma sp. Further analysis, including qPCR and sequencing, revealed that the snails were infected with Schistosoma haematobium. ConclusionWe report the first data on the identification of snails by MALDI-TOF MS in Gabon and show that Bu. truncatus and Bu. forskalii are potential intermediate hosts of S. haematobium. We also show a heterogeneous spatiotemporal distribution of snails in south-eastern Gabon. The role of G. costulatus in the transmission of schistosome remains unclear. Author SummarySchistosomiasis is a disease caused by trematodes of the genus Schistosoma. Freshwater snails of the genera Biomphalaria, Bulinus and Oncomelania release infectious cercariae, which are transmitted to the final host (human or animal). It is the second most widespread parasitic disease after malaria, and among the most important neglected tropical diseases in the world. Snail identification is extremely important for monitoring snail populations and schistosomiasis. Identification has long relied on morphological criteria and molecular biology, both of which have several drawbacks. However, numerous studies have reported the performance of MALDI-TOF MS, a technology that allows species to be identified based on their proteins, as a reliable, rapid and easy-to-use tool in many fields. Recently, it has been described as an effective tool for snail identification and even for tracing the origin of the intermediate hosts of schistosomiasis. The objective of this study was to accurately identify freshwater snails, including the intermediate hosts of schistosomiasis in Gabon.

ecology↗

bioRxiv2025

Rapid identification of Biomphalaria spp. and diagnosis of Schistosoma mansoni infestation using MALDI-TOF mass spectrometry

This study explores the use of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF MS) to identify and differentiate Biomphalaria snails infected with the parasite S. mansoni, which causes schistosomiasis. The study was conducted on two snail species, Biomphalaria pfeifferi (collected in the field in Senegal) and Biomphalaria glabrata (a laboratory strain). The snails were infected in the laboratory with S. mansoni miracidia, and their infection was confirmed by cercariae emission tests and quantitative PCR. MALDI-TOF MS was then used to analyse proteins from infected and uninfected snails to identify spectral differences. Based on protein profiles, the results of MALDI-TOF mass spectrometry made it possible to accurately differentiate between S. mansoni-infected snails and uninfected snails. An increase in the number of peaks detected and their intensity was observed for the spectra of S. mansoni-infected snails compared to uninfected snails. The application of principal component analysis to these mass spectrometry profiles confirmed the discrimination between the two groups according to their infection status. In addition, specific discriminating peaks were identified for each snail species, allowing for the distinction of infected from uninfected snails. The present study revealed, for the first time, that MALDI-TOF MS appears to be a rapid, reliable, and specific tool for the diagnosis of schistosomiasis in snails, offering promising prospects for the surveillance and control of this disease in endemic areas. However, further work is needed to establish a MALDI-TOF MS reference spectra database specific to Schistosoma parasites and to standardise sample collection, storage, and preparation in order to apply this technique in the field.

zoology↗