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2021 ◽  
Author(s):  
Petra Wahle ◽  
Eric Sobierajski ◽  
Ina Gasterstädt ◽  
Nadja Lehmann ◽  
Susanna Weber ◽  
...  

The canonical view of neuronal function is that inputs are received by dendrites and somata, become integrated in the somatodendritic compartment and upon reaching a sufficient threshold, generate axonal output with axons emerging from the cell body. The latter is not necessarily the case. Instead, axons may originate from dendrites. The terms “axon carrying dendrite” (AcD) and “AcD neurons” have been coined to describe this feature. Here, we report on the diversity of axon origins in neocortical pyramidal cells. We found that in non-primates (rodent, cat, ferret, pig), 10-21% of pyramidal cells of layers II-VI had an AcD. In marked contrast, in macaque and human, this proportion was lower, and it was particularly low for supragranular neurons. Unexpectedly, pyramidal cells in the white matter of postnatal cat and aged human cortex exhibit AcDs to much higher percentages. In rodent hippocampus, AcD cells are functionally ’privileged‘, since inputs here can circumvent somatic integration and lead to immediate action potential initiation in the axon. Our findings expand the current knowledge regarding the distribution and proportion of AcD cells in neocortial regions of non-primate taxa, which strikingly differs from primates where these cells are mainly found in deeper layers and white matter.


Nuncius ◽  
2021 ◽  
Vol 36 (3) ◽  
pp. 646-675
Author(s):  
Victor Rafael Limeira-DaSilva ◽  
Juanma Sánchez Arteaga

Abstract This paper discusses Alfred Russel Wallace’s Amazonian ethnography and his collaboration with Robert Latham on the models of indigenous Amazonian peoples that were placed on display at the Crystal Palace ethnological exhibition in 1854. The reception of scholars and the public to this innovative work is also considered. Wallace’s involvement in the first British ethnological exhibition of large proportions was fundamental to the dissemination of his work, which made a valuable contribution to a field of study—the ethnology of South America—that was still in its infancy in Britain, in marked contrast to Portugal, Spain, Germany and France. Wallace’s field observations of indigenous peoples were instilled in the British imagination through the handbook to the exhibition, in which Latham stressed the importance of Wallace’s descriptions to the advancement of the field of ethnology. Indeed, Wallace’s ethnographic accounts were deemed to provide an authoritative supplement to James Prichard’s preliminary and still somewhat limited ethnological map of northern South America, contributing to the creation of a more complete picture of the indigenous Amazonian peoples of Brazil.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kazuhiro Abe ◽  
Kenta Yamamoto ◽  
Katsumasa Irie ◽  
Tomohiro Nishizawa ◽  
Atsunori Oshima

AbstractThe gastric H+,K+-ATPase mediates electroneutral exchange of 1H+/1K+ per ATP hydrolysed across the membrane. Previous structural analysis of the K+-occluded E2-P transition state of H+,K+-ATPase showed a single bound K+ at cation-binding site II, in marked contrast to the two K+ ions occluded at sites I and II of the closely-related Na+,K+-ATPase which mediates electrogenic 3Na+/2K+ translocation across the membrane. The molecular basis of the different K+ stoichiometry between these K+-counter-transporting pumps is elusive. We show a series of crystal structures and a cryo-EM structure of H+,K+-ATPase mutants with changes in the vicinity of site I, based on the structure of the sodium pump. Our step-wise and tailored construction of the mutants finally gave a two-K+ bound H+,K+-ATPase, achieved by five mutations, including amino acids directly coordinating K+ (Lys791Ser, Glu820Asp), indirectly contributing to cation-binding site formation (Tyr340Asn, Glu936Val), and allosterically stabilizing K+-occluded conformation (Tyr799Trp). This quintuple mutant in the K+-occluded E2-P state unambiguously shows two separate densities at the cation-binding site in its 2.6 Å resolution cryo-EM structure. These results offer new insights into how two closely-related cation pumps specify the number of K+ accommodated at their cation-binding site.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lede Xian ◽  
Martin Claassen ◽  
Dominik Kiese ◽  
Michael M. Scherer ◽  
Simon Trebst ◽  
...  

AbstractRecently, the twist angle between adjacent sheets of stacked van der Waals materials emerged as a new knob to engineer correlated states of matter in two-dimensional heterostructures in a controlled manner, giving rise to emergent phenomena such as superconductivity or correlated insulating states. Here, we use an ab initio based approach to characterize the electronic properties of twisted bilayer MoS2. We report that, in marked contrast to twisted bilayer graphene, slightly hole-doped MoS2 realizes a strongly asymmetric px-py Hubbard model on the honeycomb lattice, with two almost entirely dispersionless bands emerging due to destructive interference. The origin of these dispersionless bands, is similar to that of the flat bands in the prototypical Lieb or Kagome lattices and co-exists with the general band flattening at small twist angle due to the moiré interference. We study the collective behavior of twisted bilayer MoS2 in the presence of interactions, and characterize an array of different magnetic and orbitally-ordered correlated phases, which may be susceptible to quantum fluctuations giving rise to exotic, purely quantum, states of matter.


Synthesis ◽  
2021 ◽  
Author(s):  
Md. Rafikul Islam ◽  
Tohru Nishinaga ◽  
Kazunori Hirabayashi ◽  
Toshio Shimizu ◽  
Ken-ichi Sugiura

Oxidation reactions of 1,2-diarylbenzenes induce intramolecular C-C bond formation. The substrates studied here were prepared by the stepwise Suzuki-Miyaura coupling reaction that introduced 2-naphthyl, 2-anthranyl, and 2-pyrenyl groups on the ortho positions of benzene. The subsequent oxidation reaction with FeCl3 induced an oxidative C-C bond formation reaction in the interior regions of the molecules. In marked contrast to our previous observations, two C-C bonds were formed. Theoretical calculations indicated that large spin densities at the reaction positions of the bis(cation radical) and/or cation radical species are needed for the C-C bond formation. The π-expanded molecules obtained here showed bathochromic shifts in the absorption spectra and amphoteric multi-redox behavior in electrochemistry.


Author(s):  
LOUISE RICHARDSON

Abstract It is generally accepted that sight—the capacity to see or to have visual experiences—has the power to give us knowledge about things in the environment and some of their properties in a distinctive way. Seeing the goose on the lake puts me in a position to know that it is there and that it has certain properties. And it does this by, when all goes well, presenting us with these features of the goose. One might even think that it is part of what it is to be a perceptual capacity that it has this kind of epistemological power, such that a capacity that lacked this power could not be perceptual. My focus in this essay is the sense of taste—the capacity to taste things or to have taste experiences. It has sometimes been suggested that taste lacks sight-like epistemological power. I argue that taste has epistemological power of the same kind as does sight, but that as a matter of contingent fact, that power often goes unexercised in our contemporary environment. We can know about things by tasting them in the same kind of way as we can know about things by seeing them, but we often do not. I then consider the significance of this conclusion. I suggest that in one way, it matters little, because our primary interest in taste (in marked contrast to our other senses) is not epistemic but aesthetic. But, I end by suggesting, it can matter ethically.


eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Takahiro Takano ◽  
Amanda Wahl ◽  
Kai-Ting Huang ◽  
Takanori Narita ◽  
John Rugis ◽  
...  

Salivary fluid secretion involves an intricate choreography of membrane transporters to result in the trans-epithelial movement of NaCl and water into the acinus lumen. Current models are largely based on experimental observations in enzymatically isolated cells where the Ca2+ signal invariably propagates globally and thus appears ideally suited to activate spatially separated Cl and K channels, present on the apical and basolateral plasma membrane, respectively. We monitored Ca2+ signals and salivary secretion in live mice expressing GCamp6F, following stimulation of the nerves innervating the submandibular gland. Consistent with in vitro studies, Ca2+ signals were initiated in the apical endoplasmic reticulum. In marked contrast to in vitro data, highly localized trains of Ca2+ transients that failed to fully propagate from the apical region were observed. Following stimuli optimum for secretion, large apical-basal gradients were elicited. A new mathematical model, incorporating these data was constructed to probe how salivary secretion can be optimally stimulated by apical Ca2+ signals.


2021 ◽  
Author(s):  
Kazuhiro Abe ◽  
Kenta Yamamoto ◽  
Katsumasa Irie ◽  
Tomohiro Nishizawa ◽  
Atsunori Oshima

Abstract The gastric H+,K+-ATPase mediates electroneutral exchange of 1H+/1K+ per ATP hydrolysed across the membrane. Previous structural analysis of the K+-occluded E2-Pi form of H+,K+-ATPase showed a single bound K+ at cation-binding site II, in marked contrast to the two K+ occluded at sites I and II of the closely-related Na+,K+-ATPase which mediates electrogenic 3Na+/2K+ translocation across the membrane. The two pumps show significant differences in structure in and around Site I, but which are critical for blocking K+ binding in the gastric pump and contribute to binding in the sodium pump is unclear. We have a series of crystal structures and a cryo-EM structure of H+,K+-ATPase mutants with changes in the vicinity of site I based on the structure of the sodium pump. The number of bound Rb+, determined by its anomalous dispersion, remains one in the luminal-open E2BeF form of the Lys791Ser single mutant and Lys791Ser/Glu820Asp double mutant, mutation that could create space and may directly bind the cation. We next introduced mutations in peripheral residues Try340Asn and Glu936Val. A strong and spread-out Rb+ anomalous density observed in the quadruple mutant suggests that a certain population ATPases has two Rb+ bound. We then added gate-closing mutation Try799Trp and determined its cryo-EM structure in the occluded E2-AlF form. This quintuple mutant unambiguously has two separate densities at the cation-binding site. The step-wise construction of the K+ binding site offers new insight into how it is blocked in the one pump and constituted in the other.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mario I. Molina

AbstractWe examine a fractional discrete nonlinear Schrodinger dimer, where the usual first-order derivative in the time evolution is replaced by a non integer-order derivative. The dimer is nonlinear (Kerr) and $${\mathcal{{PT}}}$$ PT -symmetric, and for localized initial conditions we examine the exchange dynamics between both sites. By means of the Laplace transformation technique, the linear $${{\mathcal{{PT}}}}$$ PT dimer is solved in closed form in terms of Mittag–Leffler functions, while for the nonlinear regime, we resort to numerical computations using the direct explicit Grunwald algorithm. In general, we see that the main effect of the fractional derivative is to produce a monotonically decreasing time envelope for the amplitude of the oscillatory exchange. In the presence of $${\mathcal{{PT}}}$$ PT symmetry, the oscillations experience some amplification for gain/loss values below some threshold, while beyond threshold, the amplitudes of both sites grow unbounded. The presence of nonlinearity can arrest the unbounded growth and lead to a selftrapped state. The trapped fraction decreases as the nonlinearity is increased past a critical value, in marked contrast with the standard (non-fractional) case.


2021 ◽  
pp. 21-47
Author(s):  
Benjamin J. Wetzel

This chapter begins by exploring Roosevelt’s four years at Harvard College. The death of his father in 1878 prompted extended religious musings and the clearest evidence of youthful evangelical faith. Roosevelt married Alice Lee in 1880 and launched his political career in 1881. As a state assemblyman, Roosevelt advocated for reforms in economic and social life. The tragic death of Alice Lee and Martha Roosevelt on the same day in 1884 drove Roosevelt to the Dakota Badlands, where he became a rancher. In these years Roosevelt said much less about personal faith, a marked contrast from his upbringing. The chapter ends with his engagement to Edith Carow in 1886.


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