Biology subjects

Fricke, L.

Publications and source records attributed to Fricke, L..

2 recordsLinked to original sources

bioRxiv2026

Multipolar spindle assembly and mitotic slippage underlie symbiont-mediated asexual reproduction

Maternally inherited bacteria can profoundly impact animal biology. A notable example is the induction of thelytokous parthenogenesis: the asexual production of female offspring. Despite decades of symbiont-mediated parthenogenesis documented across diverse arthropods, the underlying cell biological mechanisms remain poorly understood. In some species of parasitic wasps, Wolbachia causes a chromosome segregation failure during the first mitotic division in unfertilized haploid embryos. This diplodizes the embryo and facilitates asexual reproduction of females. To elucidate the mechanism of mitotic failure and understand how the animal continues development, we compared meiosis and early embryonic mitoses of the parasitoid wasp, Trichogramma pretiosum, with and without their parthenogenesis-inducing Wolbachia symbiont. We show that meiosis in these animals is anastral, and embryos undergo de novo microtubule organizing center (MTOC) biogenesis prior to the first embryonic mitosis, regardless of Wolbachia. During the first mitosis, embryos with Wolbachia had increased numbers of MTOCs associated with the oocyte nucleus and formed multipolar spindles in a modified metaphase, after which chromosome segregation failed. A restitution nucleus formed, and mitotic slippage enabled the diploid nucleus to transition to interphase and replicate. Subsequent mitotic divisions inherited supernumerary MTOCs, but formed pseudo-bipolar spindles and segregated normally. These results demonstrate that Wolbachia-mediated parthenogenesis stems from altered MTOC biology, provide a structural basis for mitotic failure and the subsequent restitution. Symbiont-mediated parthenogenesis offers unique opportunities to uncover the cell biology of asexual reproduction and a fascinating model for understanding mitosis more broadly.

Developmental Biology↗

bioRxiv2021

Gut Bacterial Dysbiosis and Instability is Associated with the Onset of Complications and Mortality in COVID-19

ObjectiveThere is a growing debate about the involvement of the gut microbiome in COVID-19, although it is not conclusively understood whether the microbiome has an impact on COVID-19, or vice versa, especially as analysis of amplicon data in hospitalized patients requires sophisticated cohort recruitment and integration of clinical parameters. Here, we analyzed fecal and saliva samples from SARS-CoV-2 infected and post COVID-19 patients and controls considering multiple influencing factors during hospitalization. Design16S rRNA gene sequencing was performed on fecal and saliva samples from 108 COVID-19 and 22 post COVID-19 patients, 20 pneumonia controls and 26 asymptomatic controls. Patients were recruited over the first and second corona wave in Germany and detailed clinical parameters were considered. Serial samples per individual allowed intra-individual analysis. ResultsWe found the gut and oral microbiota to be altered depending on number and type of COVID-19-associated complications and disease severity. The occurrence of individual complications was correlated with low-risk (e.g., Faecalibacterium prausznitzii) and high-risk bacteria (e.g., Parabacteroides). We demonstrated that a stable gut bacterial composition was associated with a favorable disease progression. Based on gut microbial profiles, we identified a model to estimate mortality in COVID-19. ConclusionGut microbiota are associated with the occurrence of complications in COVID-19 and may thereby influencing disease severity. A stable gut microbial composition may contribute to a favorable disease progression and using bacterial signatures to estimate mortality could contribute to diagnostic approaches. Importantly, we highlight challenges in the analysis of microbial data in the context of hospitalization.

microbiology↗