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<jats:p> Precise spectroscopic measurements of muonic hydrogen reveal a proton radius appreciably different from the currently accepted value. <jats:named-content content-type="related-content"> [Also see Research Article by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="417" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1230016"> Antognini <jats:italic>et al.</jats:italic> </jats:related-article> ] </jats:named-content> </jats:p>

<jats:p> A new model for neurotransmitter release may be relevant for membrane fusion reactions in general. <jats:named-content content-type="related-content"> [Also see Research Article by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="421" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1230473"> Ma <jats:italic>et al.</jats:italic> </jats:related-article> ] </jats:named-content> </jats:p>

<jats:p>Genomics Explorers, an IBI prize–winning module, engages students with bioinformatics and molecular research.</jats:p>

<jats:p> A monthly roundup of recent news and projects of <jats:italic>Science</jats:italic> 's publisher, the American Association for the Advancement of Science. </jats:p>

<jats:title>Completing the Catalog</jats:title> <jats:p> Despite the widely held belief that the number of taxonomists is decreasing, there is evidence that increasing numbers of authors are describing species new to science. In parallel, several statistically sophisticated attempts have been made to better quantify the number of species that may exist on Earth, including the oceans. Estimates of recent extinction rates have also been re-examined to question whether we are in, or heading toward, an anthropogenic mass extinction event. <jats:bold> Costello <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="413" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1230318">413</jats:related-article> ) review these findings, provide hope that science will describe most species within this century, and suggest how this complete description can be facilitated. </jats:p>

<jats:title>Proton Still Too Small</jats:title> <jats:p> Despite a proton's tiny size, it is possible to measure its radius based on its charge or magnetization distributions. Traditional measurements of proton radius were based on the scattering between protons and electrons. Recently, a precision measurement of a line in the spectrum of muonium—an atom consisting of a proton and a muon, instead of an electron—revealed a radius inconsistent with that deduced from scattering studies. <jats:bold> Antognini <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="417" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1230016">417</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="405" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1233202">Margolis</jats:related-article> </jats:bold> ) examined a different spectral line of muonium, with results less dependent on theoretical analyses, yet still inconsistent with the scattering result; in fact, the discrepancy increased. </jats:p>

<jats:title>Reconstituting Synaptic Vesicle Fusion</jats:title> <jats:p> Membrane fusion reactions have been reconstituted in vitro, but often the reconstituted reactions have not directly mirrored the requirements for synaptic vesicle fusion in vivo. Previous work generally used only <jats:italic>N</jats:italic> -ethylmaleimide–sensitive factor (NSF) attachment protein SNAP receptors (SNAREs) and one or two additional components and could not explain why deletion of Munc18-1 or Munc13 abolishes neurotransmitter release completely, yielding the severe disruptions of synaptic vesicle release in knockout mouse. <jats:bold> Ma <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="421" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1230473">421</jats:related-article> , published online 20 December; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="406" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1233801">Hughson</jats:related-article> </jats:bold> ) now present a faithful reconstitution of synaptic vesicle fusion. Membrane fusion required Munc18-1 and Munc13 when the reconstitution experiments included all eight key components (three SNAREs, Munc18-1, Munc13, synaptotagmin-1, NSF, and α-SNAP). </jats:p>

<jats:title>Environmentally Friendly Ferroelectrics</jats:title> <jats:p> Ferroelectrics—which are widely used as piezo elements, sensors, and actuators—maintain charge polarization even in the absence of an external electric field. The best ferroelectric properties are found in perovskites such as barium titanate (BTO) and lead zirconate titanate; however, environmentally friendly, lead-free alternatives are highly desirable. <jats:bold> Fu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="425" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1229675">425</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="401" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1232939">Bonnell</jats:related-article> </jats:bold> ) find that the organic molecular crystal diisopropylammonium bromide has ferroelectric properties comparable to those of BTO and may represent a viable alternative to perovskites. </jats:p>

<jats:title>Radically Organic</jats:title> <jats:p> Metals such as manganese are relatively stable over a wide range of oxidation states. In contrast, purely organic compounds are rarely susceptible to incremental addition or removal of electrons without accompanying fragmentation or coupling reactions. <jats:bold> Barnes <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="429" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1228429">429</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="404" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1233633">Benniston</jats:related-article> </jats:bold> ) report a catenane (a compound comprising interlocked rings) in which the topological structure stabilizes six different states that successively differ by the presence or absence of one or two electrons in the framework. The hepta-oxidized state proved remarkably resilient to oxygen exposure. </jats:p>

<jats:title>When Stars Get Too Close</jats:title> <jats:p> Stellar outbursts used to come in two classes: supernovae and novae, the complete explosions and the thermonuclear runaways on the surface of evolved stars, respectively. Over the past two decades a class of stellar outbursts emerged with luminosities between those of novae and supernovae—intermediate-luminosity red transients (ILRTs). <jats:bold> Ivanova <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6118" page="433" related-article-type="in-this-issue" vol="339" xlink:href="10.1126/science.1225540">433</jats:related-article> ) propose that these ILRTs are the signature of common envelope events in which a lower-mass star in a close binary system is engulfed by matter transferred from its more massive and more evolved companion star. </jats:p>