A stomatin-domain protein essential for touch sensation in the mouse

Touch and mechanical pain are first detected at our largest sensory surface, the skin. The cell bodies of sensory neurons that detect such stimuli are located in the dorsal root ganglia, and subtypes of these neurons are specialized to detect specific modalities of mechanical stimuli. Molecules have been identified that are necessary for mechanosensation in invertebrates but so far not in mammals. In Caenorhabditis elegans, mec-2 is one of several genes identified in a screen for touch insensitivity and encodes an integral membrane protein with a stomatin homology domain. Here we show that about 35% of skin mechanoreceptors do not respond to mechanical stimuli in mice with a mutation in stomatin-like protein 3 (SLP3, also called Stoml3), a mammalian mec-2 homologue that is expressed in sensory neurons. In addition, mechanosensitive ion channels found in many sensory neurons do not function without SLP3. Tactile-driven behaviours are also impaired in SLP3 mutant mice, including touch-evoked pain caused by neuropathic injury. SLP3 is therefore indispensable for the function of a subset of cutaneous mechanoreceptors, and our data support the idea that this protein is an essential subunit of a mammalian mechanotransducer.     

Deposition of metal films on an ionic liquid as a basis for a lunar telescope

An optical/infrared telescope of 20-100 m aperture located on the Moon would be able to observe objects 100 to 1,000 times fainter than the proposed next generation of space telescopes. The infrared region of the spectrum is particularly important for observations of objects at redshifts z > 7. The apparent simplicity and low mass of a liquid mirror telescope, compared with a traditional pointable glass mirror, suggest that the concept should be considered further. A previously proposed liquid mirror telescope, based upon a spinning liquid metallic alloy, is not appropriate for infrared applications, which will require a liquid below 130 K. Here we report the successful coating of an ionic liquid with silver. The surface is smooth and the silver coating is stable on a timescale of months. The underlying ionic liquid does not evaporate in a vacuum and remains liquid down to a temperature of 175 K. Given that there are approximately 10(6) simple and approximately 10(18) ternary ionic liquids, it should be possible to synthesize liquids with even lower melting temperatures.     

Early human use of marine resources and pigment in South Africa during the Middle Pleistocene

Genetic and anatomical evidence suggests that Homo sapiens arose in Africa between 200 and 100 thousand years (kyr) ago, and recent evidence indicates symbolic behaviour may have appeared approximately 135-75 kyr ago. From 195-130 kyr ago, the world was in a fluctuating but predominantly glacial stage (marine isotope stage MIS6); much of Africa was cooler and drier, and dated archaeological sites are rare. Here we show that by approximately 164 kyr ago (+/-12 kyr) at Pinnacle Point (on the south coast of South Africa) humans expanded their diet to include marine resources, perhaps as a response to these harsh environmental conditions. The earliest previous evidence for human use of marine resources and coastal habitats was dated to approximately 125 kyr ago. Coincident with this diet and habitat expansion is an early use and modification of pigment, probably for symbolic behaviour, as well as the production of bladelet stone tool technology, previously dated to post-70 kyr ago. Shellfish may have been crucial to the survival of these early humans as they expanded their home ranges to include coastlines and followed the shifting position of the coast when sea level fluctuated over the length of MIS6.     

Fc receptor but not complement binding is important in antibody protection against HIV

Most successful vaccines elicit neutralizing antibodies and this property is a high priority when developing an HIV vaccine. Indeed, passively administered neutralizing antibodies have been shown to protect against HIV challenge in some of the best available animal models. For example, antibodies given intravenously can protect macaques against intravenous or mucosal SHIV (an HIV/SIV chimaera) challenge and topically applied antibodies can protect macaques against vaginal SHIV challenge. However, the mechanism(s) by which neutralizing antibodies afford protection against HIV is not understood and, in particular, the role of antibody Fc-mediated effector functions is unclear. Here we report that there is a dramatic decrease in the ability of a broadly neutralizing antibody to protect macaques against SHIV challenge when Fc receptor and complement-binding activities are engineered out of the antibody. No loss of antibody protective activity is associated with the elimination of complement binding alone. Our in vivo results are consistent with in vitro assays indicating that interaction of Fc-receptor-bearing effector cells with antibody-complexed infected cells is important in reducing virus yield from infected cells. Overall, the data suggest the potential importance of activity against both infected cells and free virus for effective protection against HIV.     

Transferrin receptor 1 is a cellular receptor for New World haemorrhagic fever arenaviruses

At least five arenaviruses cause viral haemorrhagic fevers in humans. Lassa virus, an Old World arenavirus, uses the cellular receptor alpha-dystroglycan to infect cells. Machupo, Guanarito, Junin and Sabia viruses are New World haemorrhagic fever viruses that do not use alpha-dystroglycan. Here we show a specific, high-affinity association between transferrin receptor 1 (TfR1) and the entry glycoprotein (GP) of Machupo virus. Expression of human TfR1, but not human transferrin receptor 2, in hamster cell lines markedly enhanced the infection of viruses pseudotyped with the GP of Machupo, Guanarito and Junin viruses, but not with those of Lassa or lymphocytic choriomeningitis viruses. An anti-TfR1 antibody efficiently inhibited the replication of Machupo, Guanarito, Junin and Sabia viruses, but not that of Lassa virus. Iron depletion of culture medium enhanced, and iron supplementation decreased, the efficiency of infection by Junin and Machupo but not Lassa pseudoviruses. These data indicate that TfR1 is a cellular receptor for New World haemorrhagic fever arenaviruses.     

Two new species of Xironogiton (Clitellata: Branchiobdellida) from western North America

Xironogiton, a genus of crayfish worm (order Branchiobdellida), is historically endemic to North America. To date, six species of Xironogiton have been described, including five and one from areas west and east of the Continental Divide, respectively. Recent collections of the crayfishes Pacifastacus connectens and Pacifastacus leniusculus from the endorheic Harney Basin in south-eastern Oregon, USA, revealed the presence of two previously unknown Xironogiton species, which we describe herein. Discovery and characterisation of Xironogiton bibendumi sp. nov. and Xironogiton malheurensis sp. nov. suggests that much work remains to understand branchiobdellidan diversity in western North America, and additional targeted sampling is needed to determine intra- and interspecific variation, and thus define species limits.http://www.zoobank.org/urn:lsid:zoobank.org:pub:B24AA844-4A73-48F2-B269-7CD08DC8389A http://www.zoobank.org/urn:lsid:zoobank.org:pub:F1787846-BF04-44A6-949B-551EE3453F26     

Essentially narrative explanations

This essay argues that narrative explanations prove uniquely suited to answering certain explanatory questions, and offers reasons why recognizing a type of statement that requires narrative explanations crucially informs on their assessment. My explication of narrative explanation begins by identifying two interrelated sources of philosophical unhappiness with them. The first I term the problem of logical formlessness and the second the problem of evaluative intractability. With regard to the first, narratives simply do not appear to instantiate any logical form recognized as inference licensing. But absent a means of identifying inferential links, what justifies connecting explanans and explanandum? Evaluative intractability, the second problem, thus seems a direct consequence. This essay shows exactly why these complaints prove unfounded by explicating narrative explanations in the process of answering three interrelated questions. First, what determines that an explanation has in some critical or essential respect a narrative form? Second, how does a narrative in such cases come to constitute a plausible explanation? Third, how do the first two considerations yield a basis for evaluating an explanation offered as a narrative? Answers to each of these questions include illustrations of actual narrative explanations and also function to underline attendant dimensions of evaluation.