Superior Colliculus GABAergic Neurons Are Essential for Acute Dark Induction of Wakefulness in Mice

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Life in Darwin's dust: intercontinental transport and survival of microbes in the nineteenth century

Charles Darwin, like others before him, collected aeolian dust over the Atlantic Ocean and sent it to Christian Gottfried Ehrenberg in Berlin. Ehrenberg's collection is now housed in the Museum of Natural History and contains specimens that were gathered at the onset of the Industrial Revolution. Geochemical analyses of this resource indicated that dust collected over the Atlantic in 1838 originated from the Western Sahara, while molecular-microbiological methods demonstrated the presence of many viable microbes. Older samples sent to Ehrenberg from Barbados almost two centuries ago also contained numbers of cultivable bacteria and fungi. Many diverse ascomycetes, and eubacteria were found. Scanning electron microscopy and cultivation suggested that Bacillus megaterium , a common soil bacterium, was attached to historic sand grains, and it was inoculated onto dry sand along with a non-spore-forming control, the Gram-negative soil bacterium Rhizobium sp. NGR234. On sand B. megaterium quickly developed spores, which survived for extended periods and even though the numbers of NGR234 steadily declined, they were still considerable after months of incubation. Thus, microbes that adhere to Saharan dust can live for centuries and easily survive transport across the Atlantic.     

Antigen-induced Fc receptor-dependent and -independent B cell desensitization. An elevation in [Ca2+]i is not sufficient and protein kinase C activation is not required for these pathways of surface IgM-mediated desensitization

The interaction of an Ag ligand with its B cell surface Ig (sIg) receptor can occur via an FcR-dependent or -independent pathway. We previously found that transfected TNP-specific B cells undergo both Ca2+ signaling and desensitization upon interaction with the thymus-dependent Ag TNP-OVA. Similarly, we showed that these B cells can also be desensitized by cross-linking sIg to the Fc gamma R via the formation of an Ag-antibody bridge. Thus, Ag-specific B cells can be desensitized by two different Ag-dependent events, one mediated by Ag-sIg interaction and the other by sIg-Fc gamma R cross-linking. Inasmuch as Ag-sIg and sIg-Fc gamma R interactions lead to positive and negative signaling, it was of interest to determine whether B cell desensitization mediated by these interactions occurs by one of the well known signaling pathways in B cells. We found that Ag-induced changes in [Ca2+]i could be readily dissociated from Ag-induced desensitization, indicating that a Ca(2+)-independent pathway is likely responsible for this pathway of desensitization. To determine if PKC plays a role in B cell desensitization mediated by either Ag or sIg-Fc gamma R interaction, PKC was downregulated by long term exposure to 12-O-tetradecanoylphorbol 13-acetate or inhibited by exposure of cells to staurosporine. The PKC down-regulated and inhibited cells underwent similar Ag- and Fc gamma R-dependent desensitization compared to cells containing active PKC. Taken together, these data indicate that Ag-induced desensitization of B cell signaling likely involves an event(s) that occurs either upstream or independent of Ag-induced elevations in [Ca2+]i and PKC activation.     

Myoepithelioma within the carpal tunnel: a case report and review of the literature

Myoepitheliomas of the extremity are rare and usually benign, while a minority display malignant features. This case demonstrates the diagnosis and management of myoepithelioma within the carpal tunnel. Clinical and radiological tumour features were evaluated. Hematoxylin and eosin stained tumour sections were examined, and immunohistochemistry was performed. Histology revealed a nodular mass of epithelioid cells in clusters within a myxoid/chondroid stroma. No mitoses were noted. Cytokeratins, neuron-specific enolase, synaptophysin, glial fibrillary acidic protein, and S100 were positive on immunohistochemistry. A literature review revealed very few prior reports of myoepithelioma in the wrist, and limited data concerning any relationship between recurrence and quality of surgical margins. In this case, wide local excision would have significantly compromised dominant hand function, and therefore a marginal excision was deemed appropriate in the context of bland histological features. Surgical margins noted in future case reports will aid clinical decision making.     

ER membrane–bending proteins are necessary for de novo nuclear pore formation

Nucleocytoplasmic transport occurs exclusively through nuclear pore complexes (NPCs) embedded in pores formed by inner and outer nuclear membrane fusion. The mechanism for de novo pore and NPC biogenesis remains unclear. Reticulons (RTNs) and Yop1/DP1 are conserved membrane protein families required to form and maintain the tubular endoplasmic reticulum (ER) and the postmitotic nuclear envelope. In this study, we report that members of the RTN and Yop1/DP1 families are required for nuclear pore formation. Analysis of Saccharomyces cerevisiae prp20-G282S and nup133Δ NPC assembly mutants revealed perturbations in Rtn1–green fluorescent protein (GFP) and Yop1-GFP ER distribution and colocalization to NPC clusters. Combined deletion of RTN1 and YOP1 resulted in NPC clustering, nuclear import defects, and synthetic lethality with the additional absence of Pom34, Pom152, and Nup84 subcomplex members. We tested for a direct role in NPC biogenesis using Xenopus laevis in vitro assays and found that anti-Rtn4a antibodies specifically inhibited de novo nuclear pore formation. We hypothesize that these ER membrane–bending proteins mediate early NPC assembly steps.