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61.
Gerda Venter Frank T. J. J. Oerlemans Mietske Wijers Marieke Willemse Jack A. M. Fransen Bé Wieringa 《PloS one》2014,9(5)
Macrophages constantly undergo morphological changes when quiescently surveying the tissue milieu for signs of microbial infection or damage, or after activation when they are phagocytosing cellular debris or foreign material. These morphofunctional alterations require active actin cytoskeleton remodeling and metabolic adaptation. Here we analyzed RAW 264.7 and Maf-DKO macrophages as models to study whether there is a specific association between aspects of carbohydrate metabolism and actin-based processes in LPS-stimulated macrophages. We demonstrate that the capacity to undergo LPS-induced cell shape changes and to phagocytose complement-opsonized zymosan (COZ) particles does not depend on oxidative phosphorylation activity but is fueled by glycolysis. Different macrophage activities like spreading, formation of cell protrusions, as well as phagocytosis of COZ, were thereby strongly reliant on the presence of low levels of extracellular glucose. Since global ATP production was not affected by rewiring of glucose catabolism and inhibition of glycolysis by 2-deoxy-D-glucose and glucose deprivation had differential effects, our observations suggest a non-metabolic role for glucose in actin cytoskeletal remodeling in macrophages, e.g. via posttranslational modification of receptors or signaling molecules, or other effects on the machinery that drives actin cytoskeletal changes. Our findings impute a decisive role for the nutrient state of the tissue microenvironment in macrophage morphodynamics. 相似文献
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Christian Knig Patrick Weigelt Amanda Taylor Anke Stein Wayne Dawson Franz Essl Jan Pergl Petr Pyek Mark van Kleunen Marten Winter Cyrille Chatelain Jan J. Wieringa Pavel Krestov Holger Kreft 《Ecography》2021,44(1):44-55
Island disharmony refers to the biased representation of higher taxa on islands compared to their mainland source regions and represents a central concept in island biology. Here, we develop a generalizable framework for approximating these source regions and conduct the first global assessment of island disharmony and its underlying drivers. We compiled vascular plant species lists for 178 oceanic islands and 735 mainland regions. Using mainland data only, we modelled species turnover as a function of environmental and geographic distance and predicted the proportion of shared species between each island and mainland region. We then quantified the over‐ or under‐representation of families on individual islands (representational disharmony) by contrasting the observed number of species against a null model of random colonization from the mainland source pool, and analysed the effects of six family‐level functional traits on the resulting measure. Furthermore, we aggregated the values of representational disharmony per island to characterize overall taxonomic bias of a given flora (compositional disharmony), and analysed this second measure as a function of four island biogeographical variables. Our results indicate considerable variation in representational disharmony both within and among plant families. Examples of generally over‐represented families include Urticaceae, Convolvulaceae and almost all pteridophyte families. Other families such as Asteraceae and Orchidaceae were generally under‐represented, with local peaks of over‐representation in known radiation hotspots. Abiotic pollination and a lack of dispersal specialization were most strongly associated with an insular over‐representation of families, whereas other family‐level traits showed minor effects. With respect to compositional disharmony, large, high‐elevation islands tended to have the most disharmonic floras. Our results provide important insights into the taxon‐ and island‐specific drivers of disharmony. The proposed framework allows overcoming the limitations of previous approaches and provides a quantitative basis for incorporating functional and phylogenetic approaches into future studies of island disharmony. 相似文献
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Friðgeir Grímsson Bonnie F. Jacobs Johan L. C. H. Van Valkenburg Jan J. Wieringa Alexandros Xafis Neil Tabor 《Grana》2019,58(2):81-98
The palm family, Arecaceae, is notoriously depauperate in Africa today, and its evolutionary, paleobiogeographic, and extinction history there are not well documented by fossils. In this article we report the pollen of two new extinct species of the small genus, Sclerosperma (Arecoideae), from a late Oligocene (27–28 Ma) stratum exposed along the Guang River in Chilga Wereda of north-western Ethiopia. The pollen are triporate, and the two taxa can be distinguished from each other and from modern species using a combination of light and scanning electron microscopy, which reveals variations in the finer details of their reticulate to perforate exine sculpture. We also report a palm leaf fragment from a stratum higher in the same section that is in the Arecoideae subfamily, and most likely belongs to Sclerosperma. The implications of these discoveries for the evolutionary history of this clade of African arecoid palms is that their diversification was well underway by the middle to late Oligocene, and they were much more widespread in Africa at that time than they are now, limited to West and Central Africa. Sclerosperma exhibits ecological conservatism, as today it occurs primarily in swamps and flooded forests, and the sedimentology of the Guang River deposits at Chilga indicate a heterogeneous landscape with a high water table. The matrix containing the fossil pollen is lignite, which itself indicates standing water, and a variety of plant macrofossils from higher in the section have been interpreted as representing moist tropical forest or seasonally inundated forest communities. 相似文献
67.
Comparative analysis of spatial genetic structure in an ant–plant symbiosis reveals a tension zone and highlights speciation processes in tropical Africa 下载免费PDF全文
68.
Detection and characterization of point mutations in the choroideremia candidate gene by PCR-SSCP analysis and direct DNA sequencing 下载免费PDF全文
J. A. J. M. van den Hurk T. J. R. van de Pol C. M. Molloy F. Brunsmann K. Rüther E. Zrenner A. J. L. G. Pinckers I. H. Pawlowitzki E. M. Bleeker-Wagemakers B. Wieringa H. -H. Ropers F. P. M. Cremers 《American journal of human genetics》1992,50(6):1195-1202
By making use of positional cloning strategies we recently isolated a candidate gene for choroideremia (CHM), which is transcribed in retina, choroid, and/or retinal pigment epithelium. The gene contains an open reading frame that is structurally altered in 10 CHM patients with sizable deletions and in a female patient with a balanced translocation involving the Xq21 band. Employing PCR-SSCP analysis and direct DNA sequencing we have now detected and characterized different point mutations in five patients with CHM. Each of these mutations introduces a termination codon into the open reading frame of the CHM candidate gene, thereby predicting a distinct truncated protein product. Together these findings provide convincing evidence for the candidate gene being identical with the choroideremia gene. 相似文献
69.
The nucleotide sequence of an almost complete, double-stranded cDNA of chicken Very Low Density Lipoprotein II mRNA, carried in recombinant plasmid pVLDLII 3.33 (Wieringa et al., 1979, 7: 2147-2163) is presented. A stretch of 318 nucleotides codes for the pre-VLDLII polypeptide, which consists of a 24 amino acids signal and a 82 amino acids secreted protein. The coding stretch is flanked by 57 nucleotides in the 5'-leader sequence of the mRNA, and 258 nucleotides in the 3'-non-coding region. Hypothetical self-complementary structures of parts of the mRNA are presented. 相似文献
70.
Jan W. P Kuiper Helma Pluk Frank Oerlemans Frank N van Leeuwen Frank de Lange Jack Fransen B Wieringa 《PLoS biology》2008,6(3)
Phagocytosis requires locally coordinated cytoskeletal rearrangements driven by actin polymerization and myosin motor activity. How this actomyosin dynamics is dependent upon systems that provide access to ATP at phagosome microdomains has not been determined. We analyzed the role of brain-type creatine kinase (CK-B), an enzyme involved in high-energy phosphoryl transfer. We demonstrate that endogenous CK-B in macrophages is mobilized from the cytosolic pool and coaccumulates with F-actin at nascent phagosomes. Live cell imaging with XFP-tagged CK-B and β-actin revealed the transient and specific nature of this partitioning process. Overexpression of a catalytic dead CK-B or CK-specific cyclocreatine inhibition caused a significant reduction of actin accumulation in the phagocytic cup area, and reduced complement receptor–mediated, but not Fc-γR–mediated, ingestion capacity of macrophages. Finally, we found that inhibition of CK-B affected phagocytosis already at the stage of particle adhesion, most likely via effects on actin polymerization behavior. We propose that CK-B activity in macrophages contributes to complement-induced F-actin assembly events in early phagocytosis by providing local ATP supply. 相似文献