The royal food of termites shows king and queen specificity

シロアリの王と女王の特別食を世界初解明 --王と女王の繁殖と長寿を支えるロイヤルフード--. 京都大学プレスリリース. 2023-07-13.Society in eusocial insects is based on the reproductive division of labor, with a small number of reproductive individuals supported by a large number of non-reproductive individuals. Because inclusive fitness of all colony members depends on the survival and fertility of reproductive members, sterile members provide royals with special treatment. Here we show that termite kings and queens each receive special food of a different composition from workers. Sequential analysis of feeding processes demonstrated that workers exhibit discriminative trophallaxis, indicating their decision-making capacity in allocating food to the kings and queens. LC-MS/MS analyses of the stomodeal food and midgut contents revealed king- and queen-specific compounds including diacylglycerols and short-chain peptides. DESI-MSI analyses of ¹³C-labelled termites identified phosphatidylinositol and acetyl-L-carnitine in the royal food. Comparison of the digestive tract structure showed remarkable differences in the volume ratio of the midgut-to-hindgut among castes, indicating that digestive division of labor underlies reproductive division of labor. Our demonstration of king- and queen-specific food in termites provides insight into the nutritional system that underpins the extraordinary reproduction and longevity of royals in eusocial insects

Catalytic Enantioselective Cross-Couplings of Secondary Alkyl Electrophiles with Secondary Alkylmetal Nucleophiles: Negishi Reactions of Racemic Benzylic Bromides with Achiral Alkylzinc Reagents

We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however, a new, readily available bidentate isoquinoline–oxazoline ligand furnishes excellent ee’s and good yields. The use of acyclic alkylzinc reagents as coupling partners led to the discovery of a highly unusual isomerization that generates a significant quantity of a branched cross-coupling product from an unbranched nucleophile

Mechanism and Enantioselectivity in Palladium-Catalyzed Conjugate Addition of Arylboronic Acids to β‑Substituted Cyclic Enones: Insights from Computation and Experiment

Enantioselective conjugate additions of arylboronic acids to β-substituted cyclic enones have been previously reported from our laboratories. Air- and moisture-tolerant conditions were achieved with a catalyst derived in situ from palladium(II) trifluoroacetate and the chiral ligand (S)-t-BuPyOx. We now report a combined experimental and computational investigation on the mechanism, the nature of the active catalyst, the origins of the enantioselectivity, and the stereoelectronic effects of the ligand and the substrates of this transformation. Enantioselectivity is controlled primarily by steric repulsions between the t-Bu group of the chiral ligand and the α-methylene hydrogens of the enone substrate in the enantiodetermining carbopalladation step. Computations indicate that the reaction occurs via formation of a cationic arylpalladium(II) species, and subsequent carbopalladation of the enone olefin forms the key carbon–carbon bond. Studies of nonlinear effects and stoichiometric and catalytic reactions of isolated (PyOx)Pd(Ph)I complexes show that a monomeric arylpalladium–ligand complex is the active species in the selectivity-determining step. The addition of water and ammonium hexafluorophosphate synergistically increases the rate of the reaction, corroborating the hypothesis that a cationic palladium species is involved in the reaction pathway. These additives also allow the reaction to be performed at 40 °C and facilitate an expanded substrate scope

Electric field effect on magnetic anisotropy for Fe-Pt-Pd alloys

The electric field effect on magnetic anisotropy was investigated for the FePt1-xPdx alloy films with perpendicular magnetic anisotropy. The polar magneto-optical Kerr (p-MOKE) loops were measured under the electric field application in order to evaluate the electric field-induced perpendicular magnetic anisotropy change per area (Δεperpt). A clear change in the saturation field of p-MOKE loop was observed for FePt by varying the applied electric field (ΔE). In the case of FePt, Δεperpt divided by ΔE was evaluated to be -129 (fJ/Vm). We found that the magnitude of Δεperpt / ΔE was significantly reduced with increasing x