Abstract Background Giardia lamblia , a parasitic protist of the Metamonada supergroup, has evolved one of the most diverged endocytic compartment systems investigated so far. Peripheral endocytic compartments, currently known as peripheral vesicles or vacuoles (PVs), perform bulk uptake of fluid phase material which is then digested and sorted either to the cell cytosol or back to the extracellular space. Results Here, we present a quantitative morphological characterization of these organelles using volumetric electron microscopy and super-resolution microscopy (SRM). We defined a morphological classification for the heterogenous population of PVs and performed a comparative analysis of PVs and endosome-like organelles in representatives of phylogenetically related taxa, Spironucleus spp. and Tritrichomonas foetus . To investigate the as-yet insufficiently understood connection between PVs and clathrin assemblies in G. lamblia , we further performed an in-depth search for two key elements of the endocytic machinery, clathrin heavy chain (CHC) and clathrin light chain (CLC), across different lineages in Metamonada. Our data point to the loss of a bona fide CLC in the last Fornicata common ancestor (LFCA) with the emergence of a protein analogous to CLC ( Gl ACLC) in the Giardia genus. Finally, the location of clathrin in the various compartments was quantified. Conclusions Taken together, this provides the first comprehensive nanometric view of Giardia ’s endocytic system architecture and sheds light on the evolution of Gl ACLC analogues in the Fornicata supergroup and, specific to Giardia, as a possible adaptation to the formation and maintenance of stable clathrin assemblies at PVs.
In 2006 Yamanaka and colleagues succeeded to convert somatic cells into induced pluripotent stem cells. To do so, they introduced four defined transcription factors, Oct-3/4, Sox2, Klf4 and c-Myc, by retroviral infection.
This methodology opens a new field in stem cell research, not only in terms of future medical applications but also for new approaches in gene targeting in animals where no stable ES cells are yet available like the rat.
The three goals of this work were: Firstly, the determination of differences in reprogramming efficiency in dependence of the genetic background of the rat cells used. Secondly, the generation efficiency of rat iPS (riPS) cells from wild type rat embryonic fibroblasts (REFs) before and after gene targeting. The third goal was to clarify the role of Pramel7, a protein that was recently shown to stabilize the pluripotent state of embryonic stem cells, in terms of reprogramming efficiency. For all reprogramming rounds three factors (Oct-3/4, Klf4, Sox2) were used.
By reprogramming REFs of the different genetic backgrounds no difference in the reprogramming efficiency could be obtained. The generation efficiency of riPS before and after gene targeting was similar, indicating that gene targeting does not affect the reprogramming potential. In this work we also could show that Pramel7 overexpression is sufficient to drive reprogramming in a LIF independent manner.
ABSTRACT Giardia lamblia , a parasitic protist of the metamonada supergroup, has evolved one of the most diverged endocytic compartment systems investigated so far. Peripheral endocytic compartments, currently known as peripheral vesicles or vacuoles (PVs), perform bulk uptake of fluid phase material which is then digested and sorted either to the cell cytosol or back to the extracellular space. Here, we present a quantitative morphological characterization of these organelles using volumetric electron microscopy and super-resolution microscopy (SRM). We defined a morphological classification for the heterogenous population of PVs and performed a comparative analysis of PVs and endosome-like organelles in representatives of phylogenetically-related taxa, Spironucleus spp. and Tritrichomonas foetus . To investigate the as-yet insufficiently understood connection between PVs and clathrin assemblies in G. lamblia , we further performed an in-depth search for two key elements of the endocytic machinery, clathrin heavy chain (CHC) and clathrin light chain (CLC) across different lineages in Metamonada. Our data point to the loss of a bona fide CLC in the last Fornicata common ancestor (LFCA) with the emergence of a protein analogous to CLC ( Gl ACLC) in the Giardia genus. Taken together, this provides the first comprehensive nanometric view of Giardia ’s endocytic system architecture and sheds light on the evolution of GLACLC analogues in the Fornicata supergroup and, specific to Giardia, as a possible adaptation to the formation and maintenance of stable clathrin assemblies at PVs.
The sequencing of SARS-CoV-2 RNA in wastewater is an unbiased method to detect the spread of emerging variants and to track regional infection dynamics, which is especially useful in case of limited testing and clinical sequencing. To test how major international events influence the spread of new variants we have sequenced SARS-CoV-2 RNA in the wastewater samples of Davos, Landquart, Lostallo, and St. Moritz in the Swiss canton of Grisons in the time around the international sports competitions in Davos and St. Moritz in December 2021, and additionally in May 2022 and January 2023 in Davos and St. Moritz during the World Economic Forum (WEF) in Davos. The prevalence of the variants identified from the wastewater sequencing data showed that the Omicron variant BA.1 had spread in Davos and St. Moritz during the international sporting events hosted there in December 2021. This spread was associated with an increase in case numbers, while it was not observed in Landquart and Lostallo. Another instance of new variant spread occurred during the WEF in January 2023, when the Omicron variant BA.2.75 arrived in Davos but not in St. Moritz. We can therefore conclude that major international events promote the spread of new variants in the respective host region, which has important implications for the protective measures that should be taken.
Additional file 13: Table S2. Queries used for CHC HHM profile building. Table S3. Results from Pan-Eukaryotic search of CHC homologues in available Proteomes. Table S5. Queries used for CLC HHM profile building. Table S6. Results for GlCLC search in available Giardia genomes. Table S7. Results for bona fide CLC present in other genomes/transcriptomes. Table S8. Comparison of GlCLC with bona fide CLC. Table S9. Ten best hits from HHPred.
Paratuberculosis is a chronic bacterial disease of global importance mainly in domestic and wild ruminants, caused by Mycobacterium avium subsp. paratuberculosis (MAP). In goats, paratuberculosis is mostly caused by the "C-type" (cattle) and in a few cases by the "S-type" (sheep) strain of MAP. In 2017, a caprine S-type III isolate with a new VNTR profile was identified in a Swiss alpine region. In 2018, new caprine isolates with the same novel VNTR profile originating from a farm of a close by neighboring valley were analyzed. Here we report on this MAP S-type III outbreak in a Swiss dairy goat farm in which we investigated the pathological changes, distribution and genotype of MAP tissue homogenates. Full necropsy and histological examination were undertaken on two female adult goats with a history of weight loss and intermitting diarrhea. Routine and special stains were applied to characterize the morphological changes. DNA was extracted from 33 different tissue samples and tested for MAP by qPCR targeting IS900 and F57. Subtyping was performed, using the variable number tandem repeats (VNTR) and mycobacterial interspersed repetitive units (MIRU) approach. The goats showed moderate to marked emaciation and displayed typical clinical features of paratuberculosis. A moderate granulomatous enteritis and regional lymphadenitis with a small to moderate number of acid-fast bacteria within macrophages was detected. MAP detection was mainly restricted to the gastrointestinal tract, mesenteric and hepatic lymph nodes. Subtyping the S-type isolates using a panel of eight established MIRU-VNTR loci identified a new genotype, INMV 218.
