Biology subjects

Back, M.

Publications and source records attributed to Back, M..

3 recordsLinked to original sources

bioRxiv2026

Role of the lipolysis stimulated lipoprotein receptor LSR in the regulation of macrophage lipid homeostasis and metabolic activity

In atherosclerosis, monocyte-derived macrophages in the subendothelial space of the arterial wall, become lipid-laden and pro-inflammatory. Macrophages depend on lipoprotein receptors to regulate lipid influx, thereby shaping macrophage metabolic state and potentially dictating their phenotype. The lipolysis stimulated lipoprotein receptor, LSR, contributes to lipid homeostasis and was detected by immunofluorescence in aortic atherosclerotic plaques from ApoE-/- mice and by immunoblot in macrophages. The aim was to determine the role of LSR in macrophage lipid handling by studying LSR expression and activity before (M0) or after polarization of Raw 264.7 cells using LPS/IFN{gamma} (M1) or IL-4/IL-13 (M2), respectively. LSR mRNA (0.48-fold, p < 0.001), protein levels (0.28-fold, p < 0.001) were significantly lower in M1 (iNOS+/MCP1+) as compared to M2 (CD206+/Arg1+) macrophages. LSR activity, measured as oleate-induced uptake of DiI-labelled LDL, was significantly lower in M1 as compared to M2 macrophages. siRNA-mediated LSR knockdown (87{+/-}4%, p < 0.01) in M0 cells led to significantly decreased expression of genes involved in lipid influx (LDL-R, LRP1) and transport (ABCA1), increased basal glycolysis and decreased glycolytic reserve, but without changes in inflammatory markers. Raw 264.7 macrophages transformation into foam cells by 24h incubation with oxidized LDL also led to reduced LSR activity and expression. We propose that the lower LSR expression and activity observed in M1 and foam cell macrophages contribute to reduced lipid influx and increased glycolytic state that is associated with pro-inflammatory M1 phenotype. This provides new insight towards understanding how these immune cells depend on lipoprotein receptors regulating their metabolic uptake.

cell biology↗

bioRxiv2022

Coexistence between similar invaders: The case of two cosmopolitan exotic insects

Biological invasions are usually examined in the context of their impacts on native species. However, few studies have examined the dynamics between invaders when multiple exotic species successfully coexist in a novel environment. Yet, long-term coexistence of now established exotic species has been observed in North American lady beetle communities. Exotic lady beetles Harmonia axyridis and Coccinella septempunctata were introduced for biological control in agricultural systems and have since become dominant species within these communities. In this study, we investigated coexistence via spatial and temporal niche partitioning among H. axyridis and C. septempunctata using a 31-year dataset from southwestern Michigan, USA. We found evidence of long-term coexistence through a combination of small-scale environmental, habitat, and seasonal mechanisms. Across years, H. axyridis and C. septempunctata experienced patterns of cyclical dominance likely related to yearly variation in temperature and precipitation. Within years, populations of C. septempunctata peaked early in the growing season at 550 degree days, while H. axyridis populations grew in the season until 1250 degree days, and continued to have high activity after this point. Coccinella septempunctata was generally most abundant in herbaceous crops, whereas H. axyridis did not display strong habitat preferences. These findings suggest that within this region H. axyridis has broader habitat and abiotic environmental preferences, while C. septempunctata thrives under more specific ecological conditions. These ecological differences have contributed to the continued coexistence among these two invaders. Understanding mechanisms that allow coexistence of dominant exotic species contributes to native biodiversity conservation management of invaded ecosystems. Open research statementData are already published and publicly available, with those items properly cited in this submission. This submission uses novel code, which is provided, per our requirements, in an external repository to made available in perpetuity, and are available at https://github.com/ReproducibleQM/space_invader. Data sets utilized for this research (Landis 2020) are housed at EDI here: https://portal.edirepository.org/nis/mapbrowse?packageid=knb-lter-kbs.23.30 (doi:10.6073/pasta/f0776c1574808b08c484c1f7645a7357). Weather data was downloaded directly from the Kellogg Biological Station data repository (https://lter.kbs.msu.edu/datatables/7) and downloading the full record. An archival record of these data are available at https://portal.edirepository.org/nis/mapbrowse?packageid=knb-lter-kbs.2.107 (doi:10.6073/pasta/4c30523bae14c4340e4d9c90e72f90c4). Because both databases are living and subject to update as data is collected, databases as used within this study are mirrored within the code repository as CSV files.

ecology↗

bioRxiv2019

Live detection of neural stem and glioblastoma cells by an oligothiophene derivative

Here we report a luminescent conjugated oligothiophene (LCO), named p-HTMI, for non-invasive and non-amplified real-time detection of live human patient-derived glioblastoma (GBM) cells and embryonic neural stem cells (NSCs). While p-HTMI stained only a small fraction of other cell types investigated, the mere addition of p-HTMI to the cell culture resulted in efficient detection of NSCs or GBM cells from rodents and humans within minutes. p-HTMI is functionalized with a methylated imidazole moiety resembling the side chain of histidine/histamine, and non-methylated analogues were not functional. p-HTMI were readily able to detect a subpopulation of human cells in vivo in mouse brain sections with tumors developed from orthotopically transplanted patient-derived GBM cells. Cell sorting experiments of human GBM cells demonstrated that p-HTMI labeled the same population as CD271, a proposed marker for stem cell-like cells and rapidly migrating cells in glioblastoma. Our results suggest that the LCO p-HTMI is a versatile tool for immediate and selective detection of subpopulations of neural stem and glioma cells.

bioengineering↗