Retinoids Regulate a Developmental Checkpoint for Tissue Regeneration in Drosophila

SummaryDamage to Drosophila imaginal discs elicits a robust regenerative response from the surviving tissue [1–4]. However, as in other organisms, developmental progression and differentiation can restrict the regenerative capacity of Drosophila tissues. Experiments in Drosophila and other holometabolous insects have demonstrated that either damage to imaginal tissues [5, 6] or transplantation of a damaged imaginal disc [7, 8] delays the onset of metamorphosis. Therefore, in Drosophila there appears to be a mechanism that senses tissue damage and extends the larval phase to coordinate tissue regeneration with the overall developmental program of the organism. However, how such a pathway functions remains unknown. Here we demonstrate that a developmental checkpoint extends larval growth after imaginal disc damage by inhibiting the transcription of the gene encoding PTTH, a neuropeptide that promotes the release of the steroid hormone ecdysone. Using a genetic screen, we identify a previously unsuspected role for retinoid biosynthesis in regulating PTTH expression and delaying development in response to tissue damage. Retinoid signaling plays an important but poorly defined role in several vertebrate regeneration models [9–11]. Our findings demonstrate that retinoid biosynthesis in Drosophila is important for the maintenance of a condition that is permissive for regenerative growth

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Contains reports on three research projects.National Aeronautics and Space Administration (Grant NGL-22-009-013)Joint Services Electronics Programs (U.S. Army, U.S. Navy, and U.S. Air Force) under Contract DA 28-043-AMC-02536(E

Terahertz Security Image Quality Assessment by No-reference Model Observers

To provide the possibility of developing objective image quality assessment (IQA) algorithms for THz security images, we constructed the THz security image database (THSID) including a total of 181 THz security images with the resolution of 127*380. The main distortion types in THz security images were first analyzed for the design of subjective evaluation criteria to acquire the mean opinion scores. Subsequently, the existing no-reference IQA algorithms, which were 5 opinion-aware approaches viz., NFERM, GMLF, DIIVINE, BRISQUE and BLIINDS2, and 8 opinion-unaware approaches viz., QAC, SISBLIM, NIQE, FISBLIM, CPBD, S3 and Fish_bb, were executed for the evaluation of the THz security image quality. The statistical results demonstrated the superiority of Fish_bb over the other testing IQA approaches for assessing the THz image quality with PLCC (SROCC) values of 0.8925 (-0.8706), and with RMSE value of 0.3993. The linear regression analysis and Bland-Altman plot further verified that the Fish__bb could substitute for the subjective IQA. Nonetheless, for the classification of THz security images, we tended to use S3 as a criterion for ranking THz security image grades because of the relatively low false positive rate in classifying bad THz image quality into acceptable category (24.69%). Interestingly, due to the specific property of THz image, the average pixel intensity gave the best performance than the above complicated IQA algorithms, with the PLCC, SROCC and RMSE of 0.9001, -0.8800 and 0.3857, respectively. This study will help the users such as researchers or security staffs to obtain the THz security images of good quality. Currently, our research group is attempting to make this research more comprehensive.Comment: 13 pages, 8 figures, 4 table

Hepatitis C virus infection upregulates CD55 expression on the hepatocyte surface and promotes association with virus particles

CD55 limits excessive complement activation on the host cell surface by accelerating the decay of C3 convertases. In this study, we observed that hepatitis C virus (HCV) infection of hepatocytes or HCV core protein expression in transfected hepatocytes upregulated CD55 expression at the mRNA and protein levels. Further analysis suggested that the HCV core protein or full-length (FL) genome enhanced CD55 promoter activity in a luciferase-based assay, which was further augmented in the presence of interleukin-6. Mutation of the CREB or SP-1 binding site on the CD55 promoter impaired HCV core protein-mediated upregulation of CD55. HCV-infected or core protein-transfected Huh7.5 cells displayed greater viability in the presence of CD81 and CD55 antibodies and complement. Biochemical analysis revealed that CD55 was associated with cell culture-grown HCV after purification by sucrose density gradient ultracentrifugation. Consistent with this, a polyclonal antibody to CD55 captured cell culture-grown HCV. Blocking antibodies against CD55 or virus envelope glycoproteins in the presence of normal human serum as a source of complement inhibited HCV infection. The inhibition was enhanced in the presence of both the antibodies and serum complement. Collectively, these results suggest that HCV induces and associates with a negative regulator of the complement pathway, a likely mechanism for immune evasion

Cognitive frames in corporate sustainability: managerial sensemaking with paradoxical and business case frames

Corporate sustainability confronts managers with tensions between complex economic, environmental, and social issues. Drawing on the literature on managerial cognition, corporate sustainability, and strategic paradoxes, we develop a cognitive framing perspective on corporate sustainability. We propose two cognitive frames—a business case frame and a paradoxical frame—and explore how differences between them in cognitive content and structure influence the three stages of the sensemaking process—that is, managerial scanning, interpreting, and responding with regard to sustainability issues. We explain how the two frames lead to differences in the breadth and depth of scanning, differences in issue interpretations in terms of sense of control and issue valence, and different types of responses that managers consider with regard to sustainability issues. By considering alternative cognitive frames, our argument contributes to a better understanding of managerial decision making regarding ambiguous sustainability issues, and it develops the underlying cognitive determinants of the stance that managers adopt on sustainability issues. This argument offers a cognitive explanation for why managers rarely push for radical change when faced with complex and ambiguous issues, such as sustainability, that are characterized by conflicting yet interrelated aspects

Corporate philanthropy through the lens of ethical subjectivity

The dynamic organisational processes in businesses dilute the boundaries between the individual, organisational, and societal drivers of corporate philanthropy. This creates a complex framework in which charitable project selection occurs. Using the example of European tour operators, this study investigates the mechanisms through which companies invest in charitable projects in overseas destinations. Inextricably linked to this is the increasing contestation by local communities as to how they are able to engage effectively with tourism in order to realise the benefits tourism development can bring. This research furthers such debates by exploring the processes through which tour operators facilitate community development through charitable giving. Findings show, with no formal frameworks in existence, project selection depends upon emergent strategies that connect the professional with the personal, with trust being positioned as a central driver of these informal processes. Discretionary responsibilities are reworked through business leaders’ commitment to responsible business practises and the ethical subjectivity guiding these processes

Charge Transport and Photocurrent Generation Characteristics in Dye Solar Cells Containing Thermally Degraded N719 Dye Molecules

By deliberately introducing the thermally degraded form of the dye solar cell sensitizer N719 in dye-sensitized solar cells (DSCs) using synthetically prepared N719-TBP ([Ru(L-H)(2)(NCS)(4-tert-butylpyridine)](-+)N-(Bu)(4)), we have investigated the devastating influence of this ligand substitution product (N719-TBP) on the performance parameters of the cells. Two types of dyed solar cells, based on either N719 or N719-TBP, have been characterized employing standard current-voltage (I-V) performance test, UV-vis optical spectroscopy, incident photon to current efficiency (IPCE), and electrochemical impedance spectroscopy (EIS) methods. The performance tests show a drastic efficiency reduction of similar to 50% in the N719-TBP containing cells as compared to N719-dyed cells. The lower performance of N719-TBP was caused by lower overall light harvesting efficiency due to ca. 30 nm blue shift in the absorption spectrum of the dye, ca. 50% shorter electron diffusion length due to lower electron recombination resistance, and ca. 14% lower charge separation efficiency, which most likely can be ascribed to decreased dye regeneration efficiency caused by the replacement of one NCS ligand with TBP in the substitution product. The observations made in this study of DSC cells dyed with the substitution product, representing a worst case scenario of cells with 100% degraded dye, are in agreement with the characteristics of N719-dyed solar cells degraded at 85 degrees C, where the effect of ligand substitution is somewhat less pronounced