The global seismographic network reveals atmospherically coupled normal modes excited by the 2022 Hunga Tonga Eruption

Summary The eruption of the submarine Hunga Tonga-Hunga Haʻapai (Hunga Tonga) volcano on January 15, 2022, was one of the largest volcanic explosions recorded by modern geophysical instrumentation. The eruption was notable for the broad range of atmospheric wave phenomena it generated and for their unusual coupling with the oceans and solid Earth. The event was recorded worldwide across the Global Seismographic Network (GSN) by seismometers, microbarographs, and infrasound sensors. The broadband instrumentation in the GSN allows us to make high fidelity observations of spheroidal solid Earth normal modes from this event at frequencies near 3.7 and 4.4 mHz. Similar normal modes reported following the 1991 Pinatubo (Volcanic Explosivity Index of 6) eruption and were predicted, by theory, to arise from the excitation of mesosphere-scale acoustic modes of the atmosphere coupling with the solid Earth. Here, we compare observations for the Hunga Tonga and Pinatubo eruptions and find that both strongly excited the Earth normal mode 0S29 (3.72 mHz) and that the modal amplitude was roughly 11 times larger for the 2022 Hunga Tonga eruption. Estimates of attenuation (Q) for 0S29 across the GSN from temporal modal decay give Q = 332 ± 101, which is higher than estimates of Q for this mode using earthquake data (Q = 186.9 ± 5; Dziewonski &amp; Anderson 1981). Two microbarographs located at regional distances (&amp;lt; 1000 km) to the volcano provide direct observations of the fundamental acoustic mode of the atmosphere. These pressure oscillations, first observed approximately 40 minutes after the onset of the eruption, are in phase with the seismic Rayleigh wave excitation and are recorded only by microbarographs in proximity (&amp;lt; 1500 km) to the eruption. We infer that excitation of fundamental atmospheric modes occurs within a limited area close to the site of the eruption, where they excite select solid Earth fundamental spheroidal modes of similar frequencies that are globally recorded and have a higher apparent Q due to the extended duration of atmospheric oscillations.</jats:p

Evaluation of Pax6 Mutant Rat as a Model for Autism

Autism is a highly variable brain developmental disorder and has a strong genetic basis. Pax6 is a pivotal player in brain development and maintenance. It is expressed in embryonic and adult neural stem cells, in astrocytes in the entire central nervous system, and in neurons in the olfactory bulb, amygdala, thalamus, and cerebellum, functioning in highly context-dependent manners. We have recently reported that Pax6 heterozygous mutant (rSey2/+) rats with a spontaneous mutation in the Pax6 gene, show impaired prepulse inhibition (PPI). In the present study, we further examined behaviors of rSey2/+ rats and revealed that they exhibited abnormality in social interaction (more aggression and withdrawal) in addition to impairment in rearing activity and in fear-conditioned memory. Ultrasonic vocalization (USV) in rSey2+ rat pups was normal in male but abnormal in female. Moreover, treatment with clozapine successfully recovered the defects in sensorimotor gating function, but not in fear-conditioned memory. Taken together with our prior human genetic data and results in other literatures, rSey2/+ rats likely have some phenotypic components of autism

Crystal structure of human indoleamine 2,3-dioxygenase: Catalytic mechanism of O(2) incorporation by a heme-containing dioxygenase

Human indoleamine 2,3-dioxygenase (IDO) catalyzes the cleavage of the pyrrol ring of l-Trp and incorporates both atoms of a molecule of oxygen (O(2)). Here we report on the x-ray crystal structure of human IDO, complexed with the ligand inhibitor 4-phenylimidazole and cyanide. The overall structure of IDO shows two α-helical domains with the heme between them. A264 of the flexible loop in the heme distal side is in close proximity to the iron. A mutant analysis shows that none of the polar amino acid residues in the distal heme pocket are essential for activity, suggesting that, unlike the heme-containing monooxygenases (i.e., peroxidase and cytochrome P450), no protein group of IDO is essential in dioxygen activation or proton abstraction. These characteristics of the IDO structure provide support for a reaction mechanism involving the abstraction of a proton from the substrate by iron-bound dioxygen. Inactive mutants (F226A, F227A, and R231A) retain substrate-binding affinity, and an electron density map reveals that 2-(N-cyclohexylamino)ethane sulfonic acid is bound to these residues, mimicking the substrate. These findings suggest that strict shape complementarities between the indole ring of the substrate and the protein side chains are required, not for binding, but, rather, to permit the interaction between the substrate and iron-bound dioxygen in the first step of the reaction. This study provides the structural basis for a heme-containing dioxygenase mechanism, a missing piece in our understanding of heme chemistry