Biology subjects

Kaethner, M.

Publications and source records attributed to Kaethner, M..

3 recordsLinked to original sources

bioRxiv2026

Coordinated development of the male and female reproductive systems in the cestode Hymenolepis microstoma

BackgroundCestodes have complex hermaphroditic reproductive systems that produce massive numbers of eggs. This reproductive output is made possible by the continuous production of serially repeated sets of reproductive systems (proglottids). However, their reproductive development remains poorly understood. ResultsWe characterized reproductive development in the model cestode Hymenolepis microstoma by analyzing markers of cell proliferation, meiosis, and differentiation along the series of proglottids. Reproductive development begins with the formation of a central genital primordium, from which the reproductive ducts and gonads differentiate. Development is proterandrous, and testicular development is prolonged. In contrast, female reproductive development occurs over a short interval and is characterized by the coordinated differentiation of the ovary and vitelline gland. Entry of oocytes into meiosis is almost synchronous, and paralleled by cell proliferation in the vitelline gland. Subsequent growth of arrested oocytes and differentiation of vitelline cells occur in parallel. Insemination coincides with the onset of ovarian meiosis, indicating a close temporal coordination between male and female reproductive development. Finally, we show that gametogenesis and insemination proceed in adult worms maintained in vitro. ConclusionsOur findings show the coordination of reproductive development in a self-fertile hermaphrodite, and provide an experimental system for studying reproductive development in cestodes.

Developmental Biology↗

bioRxiv2024

Investigation of the threonine metabolism of Echinococcus multilocularis: the threonine dehydrogenase as a potential drug target in alveolar echinococcosis

Alveolar echinococcosis (AE) is a severe zoonotic disease caused by the metacestode stage of the fox tapeworm Echinococcus multilocularis. We recently showed that E. multilocularis metacestode vesicles scavenge large amounts of L-threonine from the culture medium that were neither stored nor overused for protein synthesis. This motivated us to study the effect of L-threonine on the parasite and how it is metabolized. We established a novel metacestode vesicle growth assay with an automated readout, which showed that L-threonine treatment led to significantly increased parasite growth. In addition, L-threonine increased the formation of novel metacestode vesicles from primary parasite cell cultures in contrast to the non-proteinogenic threonine analog 3-hydroxynorvaline. Tracing of [U-13C]-L-threonine and metabolites in metacestode vesicles and culture medium resulted in the detection of [U-13C]-labeling in aminoacetone and glycine, indicating that L-threonine was metabolized by threonine dehydrogenase (TDH). In addition, the detection of [13C2]-glutathione, suggested that E. multilocularis metacestode vesicles synthesize glutathione via L-threonine-derived glycine. EmTDH-mediated threonine metabolism in the E. multilocularis metacestode stage was further confirmed by quantitative real-time PCR, which demonstrated high expression of emtdh in in vitro cultured metacestode vesicles and also in metacestode samples obtained from infected animals. EmTDH was enzymatically active in metacestode vesicle extracts. Thus, the drugs disulfiram, myricetin, quercetin, sanguinarine and seven quinazoline carboxamides were assessed for inhibition of recombinantly expressed EmTDH, and the most potent inhibitors disulfiram, myricetin and sanguinarine were further tested for activity against E. multilocularis metacestode vesicles and primary parasite cells. Sanguinarine exhibited significant in vitro activity and IC50-values for metacestode vesicles, primary parasite cells, as well as mammalian cells were determined. Our results suggest that sanguinarine treatment should be further assessed in vivo employing suitable AE mouse models. Furthermore, the EmTDH assay could serve as high-throughput target-based discovery platform for novel anti-echinococcal compounds.

microbiology↗

bioRxiv2023

Establishment and application of unbiased in vitro drug screening assays for the identification of compounds against Echinococcus granulosus s.s.

Echinococcus multilocularis and E. granulosus s.l. are the causative agents of alveolar and cystic echinococcosis, respectively. Drug treatment options for these severe and neglected diseases are limited to benzimidazoles, which are not always efficacious, and adverse side effects are reported. Thus, novel and improved treatments are needed. In this study, the previously established platform for E. multilocularis in vitro drug assessment was adapted to E. granulosus s.s.. In a first step, in vitro culture protocols for E. granulosus s.s. were established. This resulted in the generation of large amounts of E. granulosus s.s. metacestode vesicles as well as germinal layer (GL) cells. In vitro culture of these cells formed metacestode vesicles displaying structural characteristics of metacestode vesicles generated in vivo. Next, drug susceptibilities of E. multilocularis and E. granulosus s.s. protoscoleces, metacestode vesicles and GL cells were comparatively assessed employing established assays including (i) metacestode vesicle damage marker release assay, (ii) metacestode vesicle viability assay, (iii) GL cell viability assay, and (iv) protoscolex motility assay. The standard drugs albendazole, buparvaquone, mefloquine, MMV665807, monepantel, niclosamide and nitazoxanide were included. MMV665807, niclosamide and nitazoxanide were active against the parasite in all four assays against both species. MMV665807 and monepantel were significantly more active against E. multilocularis metacestode vesicles, while albendazole and nitazoxanide were significantly more active against E. multilocularis GL cells. Albendazole displayed activity against E. multilocularis GL cells, but no effects were seen in albendazole-treated E. granulosus s.s. GL cells within five days. Treatment of protoscoleces with albendazole and monepantel had no impact on motility. Similar results were observed for both species with praziquantel and its enantiomers against protoscoleces. In conclusion, in vitro culture techniques and drug screening methods previously established for E. multilocularis were successfully implemented for E. granulosus s.s., allowing comparisons of drug efficacy between the two species.

pharmacology and toxicology↗