Biology subjects

CROBU, L.

Publications and source records attributed to CROBU, L..

3 recordsLinked to original sources

bioRxiv2025

A novel Leishmania infantum reference strain for gene editing and the study of visceral leishmaniasis

Parasites of the Leishmania donovani complex are responsible for visceral leishmaniasis, a vector-borne disease transmitted through the bite of female phlebotomine sand flies. As well as the human hosts, these parasites infect many mammals which can serve as reservoirs. Dogs are particularly important reservoirs in Europe. Transmission is widespread across Asia, Africa, the Americas, and the Mediterranean basin, including South of France. Visceral leishmaniasis poses a fatal threat if left untreated. Research into the pathophysiology of this neglected disease is of prime importance, as is the development of new drugs. In this study, we evaluated the growth, differentiation, and macrophage infectivity of four L. donovani complex strains and identified L. infantum S9F1 (MHOM/MA/67/ITMAP263, clone S9F1) as a well-adapted strain for genetic engineering studies. We present here the genome sequence and annotation of L infantum S9F1 T7 Cas9, providing the scientific community with easy access to its genomic information. The data has been integrated into the LeishGEdit online resource to support primer design for CRISPR-Cas9 experiments. We now aim to make this strain widely available to foster pathogenesis studies of visceral leishmaniasis. AUTHOR SUMMARYVisceral leishmaniasis is a disease caused by parasites of the Leishmania donovani complex. These parasites are spread to humans and animals through the bites of sand flies, and this disease affects millions of people worldwide, particularly in regions such as the Americas, Asia, Africa, and the Mediterranean basin. If left untreated, it can be fatal. Researchers need to study the biology of the parasite that causes the disease to better understand how it develops and progresses. In this study, we identified a L. infantum strain that is amenable to genetic modification in the laboratory and may serve as a representative model of the causative agent of visceral leishmaniasis. We tested two CRISPR-Cas9 strategies on this strain, re-sequenced and annotated its genome, and made the data available on the LeishGEdit website. By sharing this strain with the research community, we aim to support further studies on the pathogenesis of visceral leishmaniasis.

microbiology↗

bioRxiv2024

Stranded short nascent strand sequencing reveals the topology of eukaryotic DNA replication origins in Trypanosoma brucei.

The universal features that define genomic regions acting as replication origins remain unclear. In this study, we mapped a set of origins in Trypanosoma brucei using stranded short nascent strand sequencing method. Our results showed that DNA replication predominantly initiates in intergenic regions between poly(dA)- and poly(dT)-enriched sequences. G4 structures were detected in the vicinity of some origins and were embedded in poly(dA)-enriched sequences in a strand-specific manner: G4s on the plus strand were located upstream, while those on the minus strand were located downstream of the centre. The origins centres were found to be areas of low nucleosome occupancy, surrounded by regions of high nucleosome occupancy. Furthermore, our results demonstrate that 90% of replication origins overlap with a minor proportion of the previously reported RNA: DNA hybrids. These findings shed new light on the sequence and structural features that define the topology of replication origins in T. brucei. To further characterize replication dynamics at the single-molecule level, we employed DNA combing analysis.

genomics↗

bioRxiv2024

Apoptotic proteins in Leishmania donovani: In silico screening, modelling, and validation by knock-out and gene expression analysis

Visceral leishmaniasis (VL), a life-threatening vector-borne illness that disproportionately affects children and elderly immunocompromised people, is a primary tropical neglected disease. No apoptotic partner proteins in L. donovani have been reported yet, which might contribute to the knowledge of parasite cell death and the establishment of alternative therapeutics. We used the Orthologues algorithm to search for the mammalian Bcl-2 family proteins orthologs, one anti-apoptotic and two pro-apoptotic, in L. donovani. We also included a pro-death aquaporin (AQP) protein due to its characteristic BH3 domain, which is known to interact with pro-apoptotic proteins in mammals. Molecular docking and molecular dynamics simulation studies were conducted to assess the protein-protein interaction between the identified apoptotic proteins and mimic mammalian intrinsic apoptotic pathways. The results showed that the pro-apoptotic protein interacted with the hydrophobic pocket of the anti-apoptotic ortholog, forming a stable complex, which may represent a critical event in the apoptotic pathways of leishmaniasis. To further establish an apoptotic pathway in L. donovani, we used several CRISPR-Cas9 approaches to target the identified proteins. The pure knocked population mutants, and episomal over-expressing mutant cells were exposed to apoptotic stimuli. TUNEL assay and quantitative expression profiling suggested that these proteins are needed during the parasites apoptosis and could play a role in the parasites survival. Author SummaryVisceral leishmaniasis, a fatal systemic infection affecting internal organs, is one of three types of leishmaniasis in mammals alongside cutaneous and mucocutaneous leishmaniasis. It predominantly occurs in tropical and subtropical climatic zones, Leishmania donovani predominant in the Indian subcontinent and Leishmania infantum in the Mediterranean basin, the Middle East, Central Asia, South America, and Central America. This disease primarily affects children, immunocompromised adults, and the elderly. L donovani, transmitted by the infected sandflies complete its life cycle in humans, serving as reservoir. During its life cycle, at a particular stage, the parasite undergoes apoptotic-like events, yet underlying proteins or key factors remain unidentified. Using computational methods, we screened the L. donovani genome for potential candidate genes of the Bcl-2 family apoptotic proteins. We biologically/experimentally validated our in-silico findings using molecular editing tools like CRISPR-Cas9, advancing our understanding of the parasites apoptotic pathway. Targeting this pathway could lead to more effective therapeutics against visceral leishmaniasis.

microbiology↗