CorrectionsNEUROSCIENCE. For the article ''A molecular neuroethological approach for identifying and characterizing a cascade of behaviorally regulated genes,''
Learned vocalization, the substrate for human language, is a rare trait. It is found in three distantly related groups of birds-parrots, hummingbirds, and songbirds. These three groups contain cerebral vocal nuclei for learned vocalization not found in their more closely related vocal nonlearning relatives. Here, we cloned 21 receptor subunits/subtypes of all four glutamate receptor families (AMPA, kainate, NMDA, and metabotropic) and examined their expression in vocal nuclei of songbirds. We also examined expression of a subset of these receptors in vocal nuclei of hummingbirds and parrots, as well as in the brains of dove species as examples of close vocal nonlearning relatives. Among the 21 subunits/subtypes, 19 showed higher and/or lower prominent differential expression in songbird vocal nuclei relative to the surrounding brain subdivisions in which the vocal nuclei are located. This included relatively lower levels of all four AMPA subunits in lMAN, strikingly higher levels of the kainite subunit GluR5 in the robust nucleus of the arcopallium (RA), higher and lower levels respectively of the NMDA subunits NR2A and NR2B in most vocal nuclei and lower levels of the metabotropic group I subtypes (mGluR1 and -5) in most vocal nuclei and the group II subtype (mGluR2), showing a unique expression pattern of very low levels in RA and very high levels in HVC. The splice variants of AMPA subunits showed further differential expression in vocal nuclei. Some of the receptor subunits/subtypes also showed differential expression in hummingbird and parrot vocal nuclei. The magnitude of differential expression in vocal nuclei of all three vocal learners was unique compared with the smaller magnitude of differences found for nonvocal areas of vocal learners and vocal nonlearners. Our results suggest that evolution of vocal learning was accompanied by differential expression of a conserved gene family for synaptic transmission and plasticity in vocal nuclei. They also suggest that neural activity and signal transduction in vocal nuclei of vocal learners will be different relative to the surrounding brain areas.
Ongoing ocean acidification is widely reported to reduce the ability of calcifying marine organisms to produce their shells and skeletons. Whereas increased dissolution due to acidification is a largely inorganic process, strong organismal control over biomineralization influences calcification and hence complicates predicting the response of marine calcifyers. Here we show that calcification is driven by rapid transformation of bicarbonate into carbonate inside the cytoplasm, achieved by active outward proton pumping. Moreover, this proton flux is maintained over a wide range of pCO2 levels. We furthermore show that a V-type H+ ATPase is responsible for the proton flux and thereby calcification. External transformation of bicarbonate into CO2 due to the proton pumping implies that biomineralization does not rely on availability of carbonate ions, but total dissolved CO2 may not reduce calcification, thereby potentially maintaining the current global marine carbonate production.
A giant earthquake occasionally occurs in a subduction zone owing to a simultaneous rupture in adjacent segments which have been previously ruptured by large earthquakes. However, it is still unknown if a giant earthquake coincidentally occurs, or if there is a causal factor to control its generation. In this study we show a cause and a growth process of a giant earthquake which may occur along southwestern Japan, on the basis of seismic images obtained from wide‐angle seismic data and a numerical simulation incorporating the structural images. The wide‐angle seismic data were acquired along three trough parallel profiles crossing the rupture segmentation boundary between the 1944 Tonankai (moment magnitude Mw = 8.1) and the 1946 Nankai (Mw = 8.4) earthquakes. The seismic imaging detected a high seismic velocity body forming a strongly coupled patch at the segmentation boundary. The numerical simulation explained the historic rupture patterns and shows the occurrence of a giant earthquake along the entire Nankai trough, a distance of over 600 km long (Mw = 8.7). The growth process revealed from the simulated slip history in and around the strongly coupled patch is: (1) Prior to the giant earthquake, a small slow event (or earthquake) occurs near the segmentation boundary; (2) this accelerates a very slow slip (slower than the plate convergent rate), at the strong patch, which reduces a degree of coupling; and (3) then a rupture easily propagates through the strong patch when the next earthquake is nucleated near the segmentation boundary, consequently growing into a giant earthquake.
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