Biology subjects

Tyml, T.

Publications and source records attributed to Tyml, T..

4 recordsLinked to original sources

bioRxiv2025

A geothermal amoeba sets a new upper temperature limit for eukaryotes

The study of temperature limits has transformed our knowledge of the boundaries of life but has been largely focused on bacteria and archaea. We isolated a novel geothermal amoeba, Incendiamoeba cascadensis, that divides at 63{degrees}C (145.4{degrees}F), establishing a new record for the upper temperature limit across all eukaryotes. We demonstrated cellular proliferation with growth experiments and visualized mitosis via expansion microscopy. Using high-temperature live-cell imaging, we quantified movement up to 64{degrees}C. We assembled the genome of I. cascadensis and using comparative genomics found an enrichment of genes related to proteostasis, genome stability, and sensing the external environment. Taken together, our findings challenge the current paradigm of temperature constraints on eukaryotic cells and reshape our understanding of where and how eukaryotic life can persist.

microbiology↗

bioRxiv2024

Label-free structural imaging of plant roots and microbes using third- harmonic generation microscopy

Root biology is pivotal in addressing global challenges including sustainable agriculture and climate change. However, roots have been relatively understudied among plant organs, partly due to the difficulties in imaging root structures in their natural environment. Here we used microfabricated ecosystems (EcoFABs) to establish growing environments with optical access and employed nonlinear multimodal microscopy of third-harmonic generation (THG) and three-photon fluorescence (3PF) to achieve label-free, in situ imaging of live roots and microbes at high spatiotemporal resolution. THG enabled us to observe key plant root structures including the vasculature, Casparian strips, dividing meristematic cells, and root cap cells, as well as subcellular features including nuclear envelopes, nucleoli, starch granules, and putative stress granules. THG from the cell walls of bacteria and fungi also provides label-free contrast for visualizing these microbes in the root rhizosphere. With simultaneously recorded 3PF fluorescence signal, we demonstrated our ability to investigate root-microbe interactions by achieving single-bacterium tracking and subcellular imaging of fungal spores and hyphae in the rhizosphere.

plant biology↗

bioRxiv2022

A centimeter-long bacterium with DNA compartmentalized in membrane-bound organelles

Cells of most bacterial species are around 2 {micro}m in length, with some of the largest specimens reaching 750 {micro}m. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, we characterized Ca. Thiomargarita magnifica, a bacterium with an average cell length greater than 9,000 {micro}m that is visible to the naked eye. We found that these cells grow orders of magnitude over theoretical limits for bacterial cell size through unique biology, display unprecedented polyploidy of more than half a million copies of a very large genome, and undergo a dimorphic life cycle with asymmetric segregation of chromosomes in daughter cells. These features, along with compartmentalization of genomic material and protein synthesis in membrane-bound organelles, indicate gain of complexity in the Thiomargarita lineage, and challenge traditional concepts of bacterial cells. One Sentence SummaryCa. T. magnifica are compartmentalized centimeter-long bacteria

cell biology↗

bioRxiv2020

Parasitic flatworms infecting thorny skate, Amblyraja radiata: infection by the monogeneans Acanthocotyle verrilli and Rajonchocotyle emarginata in Svalbard

Parasite diversity above the Arctic circle remains understudied even for commercially valuable host taxa. Thorny skate, Amblyraja radiata, is a common bycatch species with a growing commercial value. Its natural range covers both sides of the North Atlantic including the Arctic zone. Svalbard is a Norwegian archipelago located on the northwest corner of the Barents Shelf which sustains a spectacular species diversity. So far, several monogenean species have been reported infecting thorny skate across the Atlantic Ocean. In the present study, we intend to fill in the knowledge gap on monogenean parasites infecting thorny skate in the northern part of its range and thus indirectly assess the connectivity between the thorny skate populations off the Svalbard coast and from previously studied locations. 46 monogenean individuals were recovered from 11 specimens of thorny skate. Following morphological and molecular assessment, two species of monogeneans, Acanthocotyle verrilli and Rajonchocotyle emarginata, were identified. The results serve as the northernmost record for both parasite genera and the first record of monogenean species off Svalbard. Detailed morphometric evaluation revealed a relatively high level of morphological variation in A. verrilli compared to its congeners. Phylogenetic reconstruction placed A. verrilli in a well-supported clade with A. imo. Our study also suggests high diagnostic significance of sclerotised structures in the identification of Rajonchocotyle. Even though the occurrence of two directly transmitted parasite species supports the previously suggested long-distance migration of A. radiata, future studies employing highly variable genetic markers are needed to assess the ongoing and historical migration patterns. HighlightsO_LIFirst record of monogenean species in Svalbard C_LIO_LINorthernmost record for representatives of Acanthocotylidae and Hexabothriidae C_LIO_LITransatlantic occurrence of parasites supports connectivity of thorny skate populations C_LI

zoology↗