Transcriptional signatures of somatic neoblasts and germline cells in <i>Macrostomum lignano</i>

The regeneration-capable flatworm <i>Macrostomum lignano</i> is a powerful model organism to study the biology of stem cells in vivo. As a flatworm amenable to transgenesis, it complements the historically used planarian flatworm models, such as <i>Schmidtea mediterranea</i>. However, information on the transcriptome and markers of stem cells in <i>M. lignano</i> is limited. We generated a de novo transcriptome assembly and performed the first comprehensive characterization of gene expression in the proliferating cells of <i>M. lignano</i>, represented by somatic stem cells, called neoblasts, and germline cells. Knockdown of a selected set of neoblast genes, including <i>Mlig-ddx39</i>, <i>Mlig-rrm1</i>, <i>Mlig-rpa3</i>, <i>Mlig-cdk1</i>, and <i>Mlig-h2a</i>, confirmed their crucial role for the functionality of somatic neoblasts during homeostasis and regeneration. The generated <i>M. lignano</i> transcriptome assembly and gene expression signatures of somatic neoblasts and germline cells will be a valuable resource for future molecular studies in <i>M. lignano</i>

Genomic resources for the flatworm model organism Macrostomum lignano

The last two decades were marked by discoveries and breakthroughs in different biological disciplines, and stem cell biology is an example of the quickly developing field. Discovery of stem cell niches and successful reprogramming of somatic cells into pluripotent stem state are only a few step stones that recently changed our understanding of stem cells. All the recent achievements in stem cell biology also made clear the technical limitations that scientists working in the field are facing every day, limitations that become harder and harder to overcome. One of the key technical problems is a shortage of models that allow studying pluripotent stem cell in vivo, within its microenvironment. It is hard to overestimate the importance of traditional model systems, such as mice, fishes or flies, for the stem cell research, yet the need for new complementary models becomes obvious. Marine flatworm Macrostomum lignano is a recently emerged model organism. It possesses a population of adult somatic stem cells known as neoblasts, that make it an attractive model for stem cell studies. Exploring genomic resources for this organism and, more generally, developing it as a reliable model are the main goals of this thesis that we pursue by expanding the toolkit for the model, testing its suitability in different scientific fields and studying the functioning of stem cell system in the organism. To the existing toolkit available for M. lignano we add knowledge of its genomic resources. By that we mean de novo sequencing, assembling and annotation of genome and transcriptome and miRNAs profiling, but also generating massive data on gene expression in M. lignano at different developmental stages and under different conditions. Most of this data are already publicly available, and soon we plan to introduce a new online database on M. lignano gene expression that would allow everyone to benefit from the results of our work. To the list of tools for studying M. lignano we also add reliable miRNA in situ hybridization method. We tested the potential of M. lignano, as a model for different kinds of studies outside the stem cell field. First, it is an interesting organism from the evolutionary point of view, and both its genome and presumably ancient miRNA system could add a lot to our understanding of evolution of many physiological processes. Second, M. lignano can serve as a model for chemical compound screens. Studying of bioelectrical processes presents a third field where advantages of this worm model can be exploited. We also made a step forward towards understanding the functioning of stem cells in M. lignano. We identified a set of genes involved in stem cell regulation during homeostasis and regeneration, and even larger group of transcripts, expression of which is enriched in neoblasts. We also made a candidate list of miRNAs potentially involved in stem cell regulation and addressed the role of bioelectric signaling in regeneration. Finally, we initiated the studies of the mechanism involved in rapid gonad degradation following exposure to the low salinity

Genomic resources for the flatworm model organism Macrostomum lignano

The last two decades were marked by discoveries and breakthroughs in different biological disciplines, and stem cell biology is an example of the quickly developing field. Discovery of stem cell niches and successful reprogramming of somatic cells into pluripotent stem state are only a few step stones that recently changed our understanding of stem cells. All the recent achievements in stem cell biology also made clear the technical limitations that scientists working in the field are facing every day, limitations that become harder and harder to overcome. One of the key technical problems is a shortage of models that allow studying pluripotent stem cell in vivo, within its microenvironment. It is hard to overestimate the importance of traditional model systems, such as mice, fishes or flies, for the stem cell research, yet the need for new complementary models becomes obvious. Marine flatworm Macrostomum lignano is a recently emerged model organism. It possesses a population of adult somatic stem cells known as neoblasts, that make it an attractive model for stem cell studies. Exploring genomic resources for this organism and, more generally, developing it as a reliable model are the main goals of this thesis that we pursue by expanding the toolkit for the model, testing its suitability in different scientific fields and studying the functioning of stem cell system in the organism. To the existing toolkit available for M. lignano we add knowledge of its genomic resources. By that we mean de novo sequencing, assembling and annotation of genome and transcriptome and miRNAs profiling, but also generating massive data on gene expression in M. lignano at different developmental stages and under different conditions. Most of this data are already publicly available, and soon we plan to introduce a new online database on M. lignano gene expression that would allow everyone to benefit from the results of our work. To the list of tools for studying M. lignano we also add reliable miRNA in situ hybridization method. We tested the potential of M. lignano, as a model for different kinds of studies outside the stem cell field. First, it is an interesting organism from the evolutionary point of view, and both its genome and presumably ancient miRNA system could add a lot to our understanding of evolution of many physiological processes. Second, M. lignano can serve as a model for chemical compound screens. Studying of bioelectrical processes presents a third field where advantages of this worm model can be exploited. We also made a step forward towards understanding the functioning of stem cells in M. lignano. We identified a set of genes involved in stem cell regulation during homeostasis and regeneration, and even larger group of transcripts, expression of which is enriched in neoblasts. We also made a candidate list of miRNAs potentially involved in stem cell regulation and addressed the role of bioelectric signaling in regeneration. Finally, we initiated the studies of the mechanism involved in rapid gonad degradation following exposure to the low salinity

The Flatworm Macrostomum lignano Is a Powerful Model Organism for Ion Channel and Stem Cell Research

Bioelectrical signals generated by ion channels play crucial roles in many cellular processes in both excitable and nonexcitable cells. Some ion channels are directly implemented in chemical signaling pathways, the others are involved in regulation of cytoplasmic or vesicular ion concentrations, pH, cell volume, and membrane potentials. Together with ion transporters and gap junction complexes, ion channels form steady-state voltage gradients across the cell membranes in nonexcitable cells. These membrane potentials are involved in regulation of such processes as migration guidance, cell proliferation, and body axis patterning during development and regeneration. While the importance of membrane potential in stem cell maintenance, proliferation, and differentiation is evident, the mechanisms of this bioelectric control of stem cell activity are still not well understood, and the role of specific ion channels in these processes remains unclear. Here we introduce the flatworm Macrostomum lignano as a versatile model organism for addressing these topics. We discuss biological and experimental properties of M. lignano, provide an overview of the recently developed experimental tools for this animal model, and demonstrate how manipulation of membrane potential influences regeneration in M. lignano

Urban infant mortality and religion at the end of the nineteenth and in the early twentieth century: the case of Ekaterinburg, Russia

Modern demographers analyse regional and other infant mortality differentials as important factors behind the current life expectancy of Russian citizens. Historically, however, the Russian Empire is simply displayed as one block with high infant mortality rates. Also with respect to cultural background factors, Russia is often perceived as religiously homogeneous with the Orthodox Church dominating the country. In reality, Russia has a long history of coexisting religious traditions. This includes both provinces with a majority of Catholics, Muslims, Buddhists or shamanistic populations as well as territories characterized by religious diversity and significant minority religions. Our project studies minority religious groups in the Urals, a province by the Ural Mountains stretching into Asia. While no territory can claim to be truly representative of this mega-country, we believe that this centrally located province is well suited to show some of the Russian variety, including differential infant mortality among the followers of minority religions, which is the topic of this article. We employ church record microdata to study Catholics, Jews and Old Believers in the main metal-producing city of Ekaterinburg