Genome-wide CRISPR Screens Reveal Host Factors Critical for SARS-CoV-2 Infection

1. Download : Download high-res image (212KB)
2. Download : Download full-size image

     

Startling Sweet Temptations: Hedonic Chocolate Deprivation Modulates Experience,Eating Behavior,and Eyeblink Startle

Many individuals restrict their food intake to prevent weight gain. This restriction has both homeostatic and hedonic effects but their relative contribution is currently unclear. To isolate hedonic effects of food restriction, we exposed regular chocolate eaters to one week of chocolate deprivation but otherwise regular eating. Before and after this hedonic deprivation, participants viewed images of chocolate and images of high-calorie but non-chocolate containing foods, while experiential, behavioral and eyeblink startle responses were measured. Compared to satiety, hedonic deprivation triggered increased chocolate wanting, liking, and chocolate consumption but also feelings of frustration and startle potentiation during the intertrial intervals. Deprivation was further characterized by startle inhibition during both chocolate and food images relative to the intertrial intervals. Individuals who responded with frustration to the manipulation and those who scored high on a questionnaire of impulsivity showed more relative startle inhibition. The results reveal the profound effects of hedonic deprivation on experiential, behavioral and attentional/appetitive response systems and underscore the role of individual differences and state variables for startle modulation. Implications for dieting research and practice as well as for eating and weight disorders are discussed.     

Mice Lacking Platelet-Derived Growth Factor D Display a Mild Vascular Phenotype

Platelet-derived growth factor D (PDGF-D) is the most recently discovered member of the PDGF family. PDGF-D signals through PDGF receptor β, but its biological role remains largely unknown. In contrast to other members of the PDGF family of growth factors, which have been extensively investigated using different knockout approaches in mice, PDGF-D has until now not been characterized by gene inactivation in mice. Here, we present the phenotype of a constitutive Pdgfd knockout mouse model (Pdgfd^-/-), carrying a LacZ reporter used to visualize Pdgfd promoter activity. Inactivation of the Pdgfd gene resulted in a mild phenotype in C57BL/6 mice, and the offspring was viable, fertile and generally in good health. We show that Pdgfd reporter gene activity was consistently localized to vascular structures in both postnatal and adult tissues. The expression was predominantly arterial, often localizing to vascular bifurcations. Endothelial cells appeared to be the dominating source for Pdgfd, but reporter gene activity was occasionally also found in subpopulations of mural cells. Tissue-specific analyses of vascular structures revealed that NG2-expressing pericytes of the cardiac vasculature were disorganized in Pdgfd^-/- mice. Furthermore, Pdgfd^-/- mice also had a slightly elevated blood pressure. In summary, the vascular expression pattern together with morphological changes in NG2-expressing cells, and the increase in blood pressure, support a function for PDGF-D in regulating systemic arterial blood pressure, and suggests a role in maintaining vascular homeostasis.     

Mercury in blood cells—Altered elemental profiles

The study was composed of 27 persons that displayed vague symptoms similar to those of the victims of Minamata and Iraq. Skew distributions of mercury were observed in individual erythrocytes and neutrophil granulocytes when measured by PIXE. Mercury could not be detected in the platelets. The erythrocytes also displayed lowered concentrations of magnesium and zinc, together with increased concentrations of calcium and strontium. The neutrophils displayed decreased concentrations of magnesium and zinc and increased concentrations of calcium, strontium, and iron. The presence of mercury and the altered elemental profiles in the erythrocytes and the neutrophil granulocytes are suggested as early signs of exposure.     

Cell surface distribution and intracellular fate of human beta-very low density lipoprotein in cultured peritoneal mouse macrophages: a cytochemical and immunocytochemical study

The receptor-mediated endocytosis pathway of colloidal gold labeled beta-very low density lipoprotein (beta-VLDL-Au) derived from patients with familial dysbetalipoproteinemia was analyzed at the ultrastructural level in macrophages. The results showed that beta-VLDL-Au complexes were specifically recognized by a cell surface receptor of the macrophages. beta-VLDL-Au particles once bound to the randomly distributed cell surface receptors clustered in coated pits and were taken up by coated vesicles. Subsequently, the beta-VLDL-Au particles passed through tubular structures and small endosomes before deposited into large electron lucent smooth surfaced endosomes. As revealed by ruthenium red and enzyme cytochemistry the endosomes appeared to be separated from the extracellular space and did not contain acid phosphatase. There were no clear signs of passage of beta-VLDL through the Golgi complex. The accumulation of many flocculated gold particles within Ac-Pase positive vesicles suggests that beta-VLDL once internalized by the macrophages is diverted into a degradative pathway. Incubation of beta-VLDL-loaded macrophages with the hydrophobic fluorescent dye nile red revealed numerous large fluorescent bodies within the cells indicating that the macrophages accumulate large amounts of lipid droplets with time. Additional studies large amounts of lipid droplets with time. Additional studies with native beta-VLDL in conjunction with postembedding immunocytochemical techniques were used to delineate further the intracellular pathway. Immunolabeling was carried out on thin sections of LR White embedded cells using affinity-purified polyclonal rabbit antibodies against apolipoprotein B with the protein A-gold or goat anti-rabbit IgG-gold technique. Indirect visualization of beta-VLDL by these immunocytochemical studies yielded results comparable to those with gold-labeled beta-VLDL. On the basis of both indirect immunocytochemical and direct cytochemical localization of beta-VLDL it is concluded that although colloidal gold labeling of beta-VLDL molecules unquestionably modifies their morphology, their function appears to be unaltered, at least with respect to the process of receptor-mediated endocytosis.     

Transformation of Penicillium chrysogenum by a vector containing a mitochondrial origin of replication

Summary In order to establish a transformation system for P. chrysogenum autonomously replicating vectors were constructed using mitochondrial DNA sequences from the fungus. A physical map of the mt DNA of a production strain was established using ten different restriction enzymes. Unexpectedly, the mt DNA of this strain proved to be significantly smaller than that of a second strain from a culture collection (27 kb versus 49 kb). Various fragments representing about 71% of the 27 kb mt DNA were cloned and, at first, preselected for replicating activity in an intermediate host (Saccharomyces cerevisiae). Two of these fragments also promoted autonomous replication in P. chrysogenum, which was confirmed by isolation of bulk DNA and transfer into E. coli. For selection of transformants in P. chrysogenum the prokaryotic kanamycin resistance gene was used which increased about twofold the resistance against G418. Present address: Institut für Biotechnologie, Fachgebiet Mikrobiologie, Techn. Universität Berlin, Seestr. 13, D-1000 Berlin 65     

N-Deacetylation of 2-acetamido-2-deoxy-hexosecontaining oligosaccharides and polysaccharides by calcium in liquid ammonia

N-Deacetylation of 2-acetamido-2-deoxy-hexose residues is accomplished in liquid ammonia containing calcium. Oligosaccharides, lacto-N-fucopentaose II and lacto-N-difucohexaose I, containing 3,4-disubstitutedN-acetylhexosamine residues are quantitativelyN-deacetylated. When applied to polysaccharides, however, only partialN-deacetylation was achieved.Author for correspondence. AXRD