113,433 research outputs found
Settlement and Environment at Tell Mishrifeh/Qatna and Its Region. A Preliminary Reconstruction
No full textBIOSYNTHESIS OF GANGLIOSIDES CONTAINING C18/1 AND C20/1 [3-C-14]SPHINGOSINE AFTER ADMINISTRATING [1-C-14]PALMITIC ACID AND [1-C-14]STEARIC ACID TO RAT CEREBELLAR GRANULE CELLS IN CULTURE
No full textThe biosynthesis of ganglioside molecular species containing sphingosine of different structure was investigated by administrating rat cerebellar granule cells in culture with [1-C-14]palmitic and [1-C-14]stearic acids which are the precursors for sphingosine biosynthesis. The incorporation of radioactivity into the sphingosine of the ganglioside species containing C20:1 sphingosine after administrating [1-C-14]stearic acid was low in comparison with the incorporation of radioactivity into the sphingosine of ganglioside species containing C18:1 sphingosine after administration of [1-C-14]palmitic acid, but the ratio between the radioactivity incorporated in the C20:1 and the C18:1 sphingosine of C20 and C18 ganglioside species progressively increased when the cell culture was prolonged. Ceramide-containing radioactive sphingosine was found after palmitic or stearic acid administration. Ceramide-containing C20:1 sphingosine found after adding stearic acid was about 5% of that synthesized starting from palmitic acid and containing C18:1 sphingosine. Free radioactive C18:1 and C20:1 sphingosine were found after adding radioactive palmitic or stearic acid. This is representative of a catabolic process occurring after biosynthesis of the complex sphingolipid starting from the radioactive precursor. In fact it has been proved that only saturated sphingosines are used for the synthesis of complex sphingolipids, the introduction of the double bond at position four of the sphingoid chain occurring at the level of ceramide [Rother, J., van Echten, G., Schwarzmann, G. and Sandhoff, K. (1992) Biochem. Biophys. Res. Commun. 189, 14-20]. Saturated sphingosines were not present. The lack of free C20:0 sphingosine confirms the hypothesis that the C20:0 sphingosine synthesis and the process (C20:0 sphingosine-->C20:0 ceramide-->C20:1 ceramide) occur in the correct quantity for the synthesis of C20:1 gangliosides. Moreover, we found only traces of free C20:1 sphingosine, at days 8 and 15 of cell culture when the biosynthesis of complex C20:1 gangliosides and the related catabolic processes occur to a higher extent, thus excluding the idea that a large amount of C20:0 sphingosine can be acylated to C20:0 ceramide and dehydrogenated to C20:1 ceramide which, being not used for ganglioside biosynthesis, is immediately catabolised to C20:1 sphingosine
Human fibroblasts in culture metabolize differently exogenous G(M3) ganglioside species containing C18 and C20 sphingosine
No full textPreparation of radioactive G(M3) Species containing isotopically labeled C18 sphingosine or C20 sphingosine is reported and their use for studying some aspects of the sphingolipid biosynthesis in cells is discussed. Human fibroblasts in culture that have only C18 sphingolipids and G(M3) as the major gangliosides, were fed with the two radioactive G(M3) Species. The radioactive gangliosides were taken up by the cells and metabolized. The analyses of the radioactivity metabolic fate, in this model provides the following information. i - About 70-80% of the total catabolic sphingosine is re-cycled for biosynthesis of complex sphingolipids. ii - A small amount of the catabolic C20 sphingosine was re-cycled for biosynthesis of C20 sphingolipids, thus yielding complex lipids that are not naturally present in fibroblast cells. iii - A regulatory step in the biosynthesis of sphingolipid species differring long chain base content, C18 or C20 sphingosine, is in some way involved in the first steps of sphingolipid biosynthesis, and thus plays a decisive role in the availability of the long chain bases
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Pet dogs’ behavior when the owner and an unfamiliar person attend to a faux rival
No full textWhile dog owners ascribe different emotions to their pets, including jealousy, research on secondary emotions in nonhuman animals is very limited and, so far, only one study has investigated jealousy in dogs (Canis familiaris). This work explores jealousy in dogs one step further. We conducted two studies adapting a procedure devised to assess jealousy in human infants. In each study 36 adult dogs were exposed to a situation in which their owner and a stranger ignored them while directing positive attention towards three different objects: a book, a puppet and a fake dog (Study 1: furry; Study 2: plastic). Overall, the results of both studies do not provide evidence that the behavioral responses of our dogs were triggered by jealousy: we did not find a clear indication that the fake dogs were perceived as real social rivals, neither the furry nor the plastic one. Indeed, dogs exhibited a higher interest (i.e. look at, interact with) towards the fake dogs, but differences in the behavior towards the fake dog and the puppet only emerged in Study 2. In addition, many of the behaviors (protest, stress, attention seeking, aggression) that are considered distinctive features of jealousy were not expressed or were expressed to a limited extent, revealing that dogs did not actively try to regain their owner’s attention or interfere with the interaction between the owner and the faux rival. Finally, a differentiated response towards the attachment figure (the owner) and the unfamiliar person (the stranger) did not emerge. Differently from what reported in human infants, dogs’ behavior towards the attachment figure and the stranger interacting with the potential competitor (in this case, the fake dog) did not significantly differ: in both studies dogs paid attention to the owner and the stranger manipulating the fake dog to the same extent. In conclusion, we do not exclude that dogs could possess a rudimentary form of jealousy, but we suggest that research on this topic should require the use of a real social interloper (conspecific or human) and more naturalistic procedures.</div
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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