Blastocrithidia nonstop is a protist with a highly unusual nuclear genetic code, in which all three standard stop codons are reassigned to encode amino acids, with UAA also serving as a sole termination codon. In this study, we demonstrate that this parasitic flagellate is amenable to genetic manipulation, enabling gene ablation and protein tagging. Using preassembled Cas9 ribonucleoprotein complexes, we successfully disrupted and tagged the non-essential gene encoding catalase. These advances establish this single-celled eukaryote as a model organism for investigating the malleability and evolution of the genetic code in eukaryotes.

• Klíčová slova
• CRISPR‐Cas9, codon reassignment, genetic code, model organism, trypanosomatids,
• Publikační typ
• časopisecké články MeSH

The occurrence of avian blood protists is affected by multiple factors that include the characteristics of the hosts, the vectors, the parasites, as well as the environmental factors. This study provides an insight into some of the factors that influence the prevalence of avian Lankesterella, neglected but common blood parasites in breeding populations of common passerines. The highest prevalences of Lankesterella infection were observed in 1 great tit (Parus major) population at 63%, 1 blue tit (Cyanistes caeruleus) population at 49% and a sedge warbler (Acrocephalus schoenobaenus) population at 33%. Prevalence was found to be significantly influenced by sampling site followed by host age, species and sex. Julian date had no significant effect on Lankesterella prevalence. Prevalence data from different sampling sites can reveal different patterns and should be combined critically. Higher prevalence in adults suggest that the infections are chronic, which helps the parasite to persist in host populations. The differences between sexes might be related to different exposure to the transmitting vectors (e. g., mites or mosquitoes) during breeding.

• Klíčová slova
• Acrocephalidae, Apicomplexa, Lankesterellidae, Paridae, avian haemoparasites, coccidia, host–parasite interaction, passerines,
• Publikační typ
• časopisecké články MeSH

INTRODUCTION: Rhodnius prolixus is a hematophagous insect and one of the main vectors for Trypanosoma cruzi and Trypanosoma rangeli parasites in Latin America. Gut microbiota and insect immune responses affect T. cruzi and T. rangeli infection within triatomines. Particularly the Toll and IMD signaling pathways activations and how they orchestrate the antimicrobial peptides (AMPs) expressions in R. prolixus, especially when infected by T. rangeli. OBJECTIVES: Examine how T. rangeli infection modulates R. prolixus cellular and humoral immunity and its impacts on insect microbiota. METHODS: R. prolixus was fed on blood containing epimastigotes of T. rangeli, and infection was quantified in insect tissues. The gene expression of dorsal, cactus, relish, PGRP, and AMPs was examined in the midgut, fat body, and salivary glands by quantitative real-time PCR. Microbiota composition was analyzed using RT-q PCR targeting specific bacterial species. Hemocyte numbers and phenoloxidase activity were quantified to assess cellular immune responses. RESULTS: T. rangeli infection modulated triatomine immunity in midgut and hemocoel, activating the expression of the NF-kB gene dorsal, associated with the Toll pathway; increasing expression of the gene encoding PGRP receptor, a component involved in the IMD pathway, both in the intestine and fat body; repressing the expression of the relish transcription factor, mainly in salivary glands. Among the R. prolixus AMPs studied, T. rangeli infection repressed all AMP gene expression, other than defensin C which increased mRNA levels. The PO activity was enhanced in the hemolymph of infected insects. T. rangeli infection did not induce hemocyte number alterations compared to control insects. However, an increase in hemocyte microaggregation was detected in infected insects. DISCUSSION: R. prolixus recognizes T. rangeli infection and triggers humoral and cellular immune responses involving Toll pathway activation, defensin C synthesis, increased phenoloxidase activity, and enhanced hemocyte aggregation. On the other hand, T. rangeli infection suppressed some IMD pathway components, suggesting that, in R. prolixus, this pathway is involved in defensins A and B gene regulation. Importantly, these immune responses altered the bacterial microbiota composition, potentially favoring T. rangeli establishment in the insect vector.

• Klíčová slova
• Rhodnius prolixus, Trypanosoma rangeli, immunity, microbiota, signaling pathways,
• Publikační typ
• časopisecké články MeSH