0000000001082044
AUTHOR
Anita Mäki
showing 15 related works from this author
Quantitative Analysis of Dynamic Association in Live Biological Fluorescent Samples
2014
Determining vesicle localization and association in live microscopy may be challenging due to non-simultaneous imaging of rapidly moving objects with two excitation channels. Besides errors due to movement of objects, imaging may also introduce shifting between the image channels, and traditional colocalization methods cannot handle such situations. Our approach to quantifying the association between tagged proteins is to use an object-based method where the exact match of object locations is not assumed. Point-pattern matching provides a measure of correspondence between two point-sets under various changes between the sets. Thus, it can be used for robust quantitative analysis of vesicle …
Effects of alternative electron acceptors on the activity and community structure of methane-producing and consuming microbes in the sediments of two…
2017
The role of anaerobic CH4 oxidation in controlling lake sediment CH4 emissions remains unclear. Therefore, we tested how relevant EAs (SO42−, NO3−, Fe3+, Mn4+, O2) affect CH4 production and oxidation in the sediments of two shallow boreal lakes. The changes induced to microbial communities by the addition of Fe3+ and Mn4+ were studied using next-generation sequencing targeting the 16S rRNA and methyl-coenzyme M reductase (mcrA) genes and mcrA transcripts. Putative anaerobic CH4-oxidizing archaea (ANME-2D) and bacteria (NC 10) were scarce (up to 3.4% and 0.5% of archaeal and bacterial 16S rRNA genes, respectively), likely due to the low environmental stability associated with shallow depths.…
Sample Preservation, DNA or RNA Extraction and Data Analysis for High-Throughput Phytoplankton Community Sequencing
2017
Phytoplankton is the basis for aquatic food webs and mirrors the water quality. Conventionally, phytoplankton analysis has been done using time consuming and partly subjective microscopic observations, but next generation sequencing (NGS) technologies provide promising potential for rapid automated examination of environmental samples. Because many phytoplankton species have tough cell walls, methods for cell lysis and DNA or RNA isolation need to be efficient to allow unbiased nucleic acid retrieval. Here, we analyzed how two phytoplankton preservation methods, three commercial DNA extraction kits and their improvements, three RNA extraction methods, and two data analysis procedures affect…
Directional high-throughput sequencing of RNAs without gene-specific primers.
2018
Ribosomal RNA analysis is a useful tool for characterization of microbial communities. However, the lack of broad-range primers has hampered the simultaneous analysis of eukaryotic and prokaryotic members by amplicon sequencing. We present a complete workflow for directional, primer-independent sequencing of size-selected small subunit ribosomal RNA fragments. The library preparation protocol includes gel extraction of the target RNA, ligation of an RNA oligo to the 5′-end of the target, and cDNA synthesis with a tailed random-hexamer primer and further barcoding. The sequencing results of a phytoplankton mock community showed a highly similar profile to the biomass indicators. This method…
Construction of Metatranscriptomic Libraries for 5′ End Sequencing of rRNAs for Microbiome Research
2021
Metatranscriptomic sequencing enables studying community-wide gene expression profiles of microbial samples and getting functional insight on their up- or downregulated pathways. However, shotgun sequencing is not the most efficient way to study expression of ribosomal RNA genes or to compare lot of samples in experimental setups. Here we describe an efficient primer-independent method for processing and barcoding libraries for directional sequencing of the 5' end region of the RNA. When applying size selection of the original RNA, the method forms an optimal solution for the simultaneous analysis of bacterial, archaeal, and eukaryotic rRNA diversity.
Echovirus 1 infection depends on biogenesis of novel multivesicular bodies
2011
Summary Non-enveloped picornavirus echovirus 1 (EV1) clusters its receptor α2β1 integrin and causes their internalization and accumulation in α2β1 integrin enriched multivesicular bodies (α2-MVBs). Our results here show that these α2-MVBs are distinct from acidic late endosomes/lysosomes by several criteria: (i) live intra-endosomal pH measurements show that α2-MVBs are not acidic, (ii) they are not positive for the late endosomal marker LBPA or Dil-LDL internalized to lysosomes, and (iii) simultaneous stimulation of epidermal growth factor receptor (EGFR) and α2β1 integrin clustering leads to their accumulation in separate endosomes. EGFR showed downregulation between 15 min and 2 h, where…
A practical method for barcoding and size-trimming PCR templates for amplicon sequencing
2016
Sample barcoding facilitates the analysis of tens or even hundreds of samples in a single next-generation sequencing (NGS) run, but more efficient methods are needed for high-throughput barcoding and size-trimming of long PCR products. Here we present a two-step PCR approach for barcoding followed by pool shearing, adapter ligation, and 5′ end selection for trimming sets of DNA templates of any size. Our new trimming method offers clear benefits for phylogenetic studies, since targeting exactly the same region maximizes the alignment and enables the use of operational taxonomic unit (OTU)-based algorithms.
Echovirus 1 internalization negatively regulates epidermal growth factor receptor downregulation
2016
We have demonstrated previously that the human picornavirus Echovirus 1 (EV1) triggers an infectious internalization pathway that follows closely, but seems to stay separate, from the epidermal growth factor receptor (EGFR) pathway triggered by epidermal growth factor (EGF). Here, we confirmed by using live and confocal microscopy that EGFR and EV1 vesicles are following intimately each other but are distinct entities with different degradation kinetics. We show here that despite being sorted to different pathways and located in distinct endosomes, EV1 inhibits EGFR downregulation. Simultaneous treatment with EV1 and EGF led to an accumulation of EGFR in cytoplasmic endosomes, which was evi…
Calpains promote α2β1 integrin turnover in nonrecycling integrin pathway
2012
A novel virus- and integrin clustering–specific pathway diverts integrin from its normal endo/exocytic traffic to a nonrecycling degradative endosomal route. Clustering of α2β1 integrin causes redistribution of the integrin to perinuclear endosomes, leading to enhanced integrin turnover promoted by calpains.
Plants assemble species specific bacterial communities from common core taxa in three arcto-alpine climate zones
2017
Evidence for the pivotal role of plant-associated bacteria to plant health and productivity has accumulated rapidly in the last years. However, key questions related to what drives plant bacteriomes remain unanswered, among which is the impact of climate zones on plant-associated microbiota. This is particularly true for wild plants in arcto-alpine biomes. Here, we hypothesized that the bacterial communities associated with pioneer plants in these regions have major roles in plant health support, and this is reflected in the formation of climate and host plant specific endophytic communities. We thus compared the bacteriomes associated with the native perennial plants Oxyria digyna and Saxi…
Echovirus 1 internalization negatively regulates epidermal growth factor receptor downregulation
2017
We have demonstrated previously that the human picornavirus Echovirus 1 (EV1) triggers an infectious internalization pathway that follows closely, but seems to stay separate, from the epidermal growth factor receptor (EGFR) pathway triggered by epidermal growth factor (EGF). Here, we confirmed by using live and confocal microscopy that EGFR and EV1 vesicles are following intimately each other but are distinct entities with different degradation kinetics. We show here that despite being sorted to different pathways and located in distinct endosomes, EV1 inhibits EGFR downregulation. Simultaneous treatment with EV1 and EGF led to an accumulation of EGFR in cytoplasmic endosomes, which was evi…
α2β1-integriinin ja stimuloidun epidermaalisen kasvutekijä-reseptorin reittien yhteydet
2011
Integriinien ja kasvutekijäreseptorien kulku solussa yhdistyy monimutkaisen vuorovaikutusten verkoston kautta. Ympäristön olosuhteista riippuvaisesti integriinit ja kasvutekijäreseptorit kantavat pääasiallisen vastuun solun selviytymisestä, kasvusta, erilaistumisesta, vaeltamisesta ja lisääntymisestä. Integriinit kiinnittävät solut alustaansa ja kasvutekijäreseptorit voivat vastata liukoisten ligandien haasteisiin. α2β1-integriinit reagoivat ligandeihinsa, joita voivat olla matriksimolekyylit, virukset ja keinotekoisesti myös vasta-aineet. Integriinien klusterointi viruksella tai vasta-aineilla aiheuttaa integriinin internalisaation endosomeihin, kun taas sitoutuminen matriksimolekyyleihin …
Vertical stratification of bacteria and archaea in sediments of a small boreal humic lake
2019
ABSTRACT Although sediments of small boreal humic lakes are important carbon stores and greenhouse gas sources, the composition and structuring mechanisms of their microbial communities have remained understudied. We analyzed the vertical profiles of microbial biomass indicators (PLFAs, DNA and RNA) and the bacterial and archaeal community composition (sequencing of 16S rRNA gene amplicons and qPCR of mcrA) in sediment cores collected from a typical small boreal lake. While microbial biomass decreased with sediment depth, viable microbes (RNA and PLFA) were present all through the profiles. The vertical stratification patterns of the bacterial and archaeal communities resembled those in mar…
Consistency of Targeted Metatranscriptomics and Morphological Characterization of Phytoplankton Communities
2020
The composition of phytoplankton community is the basis for environmental monitoring and assessment of the ecological status of aquatic ecosystems. Community composition studies of phytoplankton have been based on time-consuming and expertise-demanding light microscopy analyses. Molecular methods have the potential to replace microscopy, but the high copy number variation of ribosomal genes and the lack of universal primers for simultaneous amplification of prokaryotic and eukaryotic genes complicate data interpretation. In this study, we used our previously developed directional primer-independent high-throughput sequencing (HTS) approach to analyze 16S and 18S rRNA community structures. C…
Original data for article: Comparison of epifluorescence microscopy and flow cytometry in counting freshwater picophytoplankton
2019
The dataset is divided into four subfolders: 1) "SEM experiment data" contains Scanning Electron Microscopy data, epifluorescence microscopy data and flow cytometry data of cultured Synechococcus, Chroococcus and Snowella 2) "raw data" contains epifluorescence microscopy and flow cytometry data of picophytoplankton from Finnish lakes. This has two sub folders "flow cytometry raw" and "microscopy raw" 3) "flow cytometry calibration data" contains data for cell size calibration with latex beads and volumetric calibration for the flow cytometer 4) "processed flow and microscopy data" contains excel workbooks for the figures shown in the manuscipt